Touchscreen

A touchscreen is a display which can detect the presence and location of a touch within the display area. The term generally refers to touch or contact to the display of the device by a finger or hand. Touchscreens can also sense other passive objects, such as a stylus. However, if the object sensed is active, as with a light pen, the term touchscreen is generally not applicable. The ability to interact directly with a display typically indicates the presence of a touchscreen.




Until the early 1980s, 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 is starting to change with the commercialisation of multi-touch technology.

The touchscreen has two main attributes. First, it enables one to interact with what is displayed directly on the screen, where it is displayed, rather than indirectly with a mouse or touchpad. Secondly, it lets one do so without requiring any intermediate device, again, such as a stylus that needs to be held in the hand. Such displays can be attached to computers or, as terminals, to networks. They also play a prominent role in the design of digital appliances such as the personal digital assistant (PDA), satellite navigation devices and mobile phones.

ability to accurately point on the screen

Virtually all of the significant touchscreen technology patents were filed during the 1970s and 1980s and have expired. Touchscreen component manufacturing and product design are no longer encumbered by royalties or legalities with regard to patents and the manufacturing of touchscreen-enabled displays on all kinds of devices is widespread.

The development of multipoint touch screens facilitated the tracking of more than one finger on the screen, thus operations that require more than one finger are possible. These devices also allow multiple users to interact with the touchscreen simultaneously.

With the growing acceptance of many kinds of products with an integral touchscreen interface the marginal cost of touchscreen technology is routinely absorbed into the products that incorporate it and is effectively eliminated. As typically occurs with any technology, touchscreen hardware and software has sufficiently matured and been perfected over more than three decades to the point where its reliability is unassailable. As such, touchscreen displays are found today in airplanes, automobiles, gaming consoles, machine control systems, appliances and handheld display devices of every kind. With the influence of the multi touch-enabled iPhone and the Nintendo DS, the touchscreen market for mobile devices is projected to produce US$5 billion in 2009.

The ability to accurately point on the screen itself is taking yet another step with the emerging graphics tablet/screen hybrids.

Conventional optical-touch systems use an array of infrared

Conventional optical-touch systems use an array of infrared (IR) light-emitting diodes (LEDs) on two adjacent bezel edges of a display, with photosensors placed on the two opposite bezel edges to analyze the system and determine a touch event. The LED and photosensor pairs create a grid of light beams across the display. An object (such as a finger or pen) that touches the screen interrupts the light beams, causing a measured decrease in light at the corresponding photosensors. The measured photosensor outputs can be used to locate a touch-point coordinate.

Widespread adoption of optical touch screens has been hampered by two factors: the relatively high cost of the technology compared to competing touch technologies and the issue of performance in bright ambient light. This latter problem is a result of background light increasing the noise floor at the optical sensor, sometimes to such a degree that the touch screen’s LED light cannot be detected at all, causing a temporary failure of the touch screen. This is most pronounced in directsunlight conditions where the sun has a very high energy distribution in the IR region.

In addition, conventional optical touch has not been adopted for small handheld touch screens (such as in cell phones and PDAs) due to a number of other technical reasons, including power consumption, mechanical packaging constraints, and resolution limitations which limit the system’s ability to detect small objects such as PDA-style pens.

However, certain features of optical touch remain desirable and represent attributes of the ideal touch screen, including the option to eliminate the glass or plastic overlay that most other touch technologies require in front of the display. In many cases, this overlay is coated with an electrically conducting transparent material such as indium tin oxide (ITO), which reduces the optical quality of the display. This advantage of optical touch screens is extremely important for many device and display vendors since devices are often sold on the perceived quality of the user display experience.

Another feature of optical touch which has been long desired is the digital nature of the sensor output when compared to many other touch systems that rely on analog-signal processing to determine a touch position. These competing analog systems normally require continual re-calibration, have complex signal-processing demands (which adds cost and power consumption), demonstrate reduced accuracy and precision compared to a digital system, and have longer-term system-failure modes due to the operating environment.

Yet another key advantage of optical touch is that there is normally no direct impact of a finger, pen, or other object with the touch recognition hardware. This reduces the possibility of failure modes typically caused by impact failure, wear, or fatigue of the touchscreen. This is also related to the requirement for low-pressure touch. In an optical-touch system, only interaction with the light beams is required – no force needs to be applied to the system for detection or activation.

Finally, optical touch is capable of implementing multi-touch, something most other touch technologies cannot easily achieve.

Neonode has taken conventional IR touch technology, using LEDs and photodiodes, and essentially miniaturized it and reduced the cost for use in handheld devices. In addition to using the technology in its own N2 cell phone, Neonode is also marketing it to other device makers.

Chumby

The Chumby is an ambient consumer electronics product made by Chumby Industries, Inc.. It is an embedded computer which provides Internet and LAN access via a Wi-Fi connection. Through this connection, the Chumby runs various software widgets.

Roughly resembling a small clock radio, it consists of a small touch-screen with a leather and plastic exterior. It uses AC power and turns off if unplugged and moved; a 9 volt battery connector is supplied for backup power. It costs $199.95 (USD) and comes in six colors.

The Chumby has been praised by some as open source hardware, although it does not exactly conform to the Open Source Definition. It is designed to be customizable by users, but some have criticized this as "goofy" and unnecessary. Wired magazine named Chumby one of its top gadgets for 2008. Its software is completely open source, running on Linux.

Embedded system

An embedded system is a special-purpose computer system designed to perform one or a few dedicated functions, often with real-time computing constraints. It is usually embedded as part of a complete device including hardware and mechanical parts. In contrast, a general-purpose computer, such as a personal computer, can do many different tasks depending on programming. Embedded systems control many of the common devices in use today.

Since the embedded system is dedicated to specific tasks, design engineers can optimize it, reducing the size and cost of the product, or increasing the reliability and performance. Some embedded systems are mass-produced, benefiting from economies of scale.

Physically, embedded systems range from portable devices such as digital watches and MP3 players, to large stationary installations like traffic lights, factory controllers, or the systems controlling nuclear power plants. Complexity varies from low, with a single microcontroller chip, to very high with multiple units, peripherals and networks mounted inside a large chassis or enclosure.

In general, "embedded system" is not an exactly defined term, as many systems have some element of programmability. For example, Handheld computers share some elements with embedded systems — such as the operating systems and microprocessors which power them — but are not truly embedded systems, because they allow different applications to be loaded and peripherals to be connected.