Electronic paper and e-paper sometimes electronic ink or e-ink, are display devices that mimic the appearance of ordinary ink on paper. Unlike conventional backlit flat panel displays that emit light, electronic paper displays reflect light like paper; this may make them more comfortable to read, provide a wider viewing angle than most light-emitting displays. The contrast ratio in electronic displays available as of 2008 approaches newspaper, newly developed displays are better. An ideal e-paper display can be read in direct sunlight without the image appearing to fade. Many electronic paper technologies hold static text and images indefinitely without electricity. Flexible electronic paper uses plastic substrates and plastic electronics for the display backplane. There is ongoing competition among manufacturers to provide full-color ability. Applications of electronic visual displays include electronic pricing labels in retail shops and digital signage, time tables at bus stations, electronic billboards, smartphone displays, e-readers able to display digital versions of books and magazines.
Electronic paper was first developed in the 1970s by Nick Sheridon at Xerox's Palo Alto Research Center. The first electronic paper, called Gyricon, consisted of polyethylene spheres between 75 and 106 micrometers across; each sphere is a janus particle composed of negatively charged black plastic on one side and positively charged white plastic on the other. The spheres are embedded in a transparent silicone sheet, with each sphere suspended in a bubble of oil so that they can rotate freely; the polarity of the voltage applied to each pair of electrodes determines whether the white or black side is face-up, thus giving the pixel a white or black appearance. At the FPD 2008 exhibition, Japanese company Soken demonstrated a wall with electronic wall-paper using this technology. In 2007, the Estonian company Visitret Displays was developing this kind of display using polyvinylidene fluoride as the material for the spheres improving the video speed and decreasing the control voltage. In the simplest implementation of an electrophoretic display, titanium dioxide particles one micrometer in diameter are dispersed in a hydrocarbon oil.
A dark-colored dye is added to the oil, along with surfactants and charging agents that cause the particles to take on an electric charge. This mixture is placed between two parallel, conductive plates separated by a gap of 10 to 100 micrometres; when a voltage is applied across the two plates, the particles migrate electrophoretically to the plate that bears the opposite charge from that on the particles. When the particles are located at the front side of the display, it appears white, because light is scattered back to the viewer by the high-index titania particles; when the particles are located at the rear side of the display, it appears dark, because the incident light is absorbed by the colored dye. If the rear electrode is divided into a number of small picture elements an image can be formed by applying the appropriate voltage to each region of the display to create a pattern of reflecting and absorbing regions. Electrophoretic displays are considered prime examples of the electronic paper category, because of their paper-like appearance and low power consumption.
Examples of commercial electrophoretic displays include the high-resolution active matrix displays used in the Amazon Kindle, Barnes & Noble Nook, Sony Librie, Sony Reader, Kobo eReader, iRex iLiad e-readers. These displays are constructed from an electrophoretic imaging film manufactured by E Ink Corporation. A mobile phone that used the technology is the Motorola Fone. Electrophoretic Display technology has been developed by Sipix and Bridgestone/Delta. SiPix is now part of E Ink; the Sipix design uses a flexible 0.15 mm Microcup architecture, instead of E Ink's 0.04 mm diameter microcapsules. Bridgestone Corp.'s Advanced Materials Division cooperated with Delta Optoelectronics Inc. in developing the Quick Response Liquid Powder Display technology. Electrophoretic displays can be manufactured using the Electronics on Plastic by Laser Release process developed by Philips Research to enable existing AM-LCD manufacturing plants to create flexible plastic displays. An electrophoretic display forms images by rearranging charged pigment particles with an applied electric field.
In the 1990s another type of electronic ink based on a microencapsulated electrophoretic display was conceived and prototyped by a team of undergraduates at MIT as described in their Nature paper. J. D. Albert, Barrett Comiskey, Joseph Jacobson, Jeremy Rubin and Russ Wilcox co-founded E Ink Corporation in 1997 to commercialize the technology. E ink subsequently formed a partnership with Philips Components two years to develop and market the technology. In 2005, Philips sold the electronic paper business as well as its related patents to Prime View International. "It has for many years been an ambition of researchers in display media to create a flexible low-cost system, the electronic analogue of paper. In this context, microparticle-based displays have long intrigued researchers. Switchable contrast in such displays is achieved by the electromigration of scattering or absorbing microparticles, quite distinct from the molecular-scale properties that govern the behaviour of the more familiar liquid-crystal displays.
Micro-particle-based displays possess intrinsic bistability, exhibit low power d.c. field addressing and have demonstrated high contrast and reflectivity. These features, combined with a near-lambertian viewing characteristic, result in an'ink on paper' look, but such displays have to date suffered from
A backplane is a group of electrical connectors in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus. It is used as a backbone to connect several printed circuit boards together to make up a complete computer system. Backplanes use a printed circuit board, but wire-wrapped backplanes have been used in minicomputers and high-reliability applications. Early microcomputer systems like the Altair 8800 used a backplane for the processor and expansion cards. A backplane is differentiated from a motherboard by the lack of on-board processing and storage elements. A backplane uses plug-in cards for processing. Backplanes are used in preference to cables because of their greater reliability. In a cabled system, the cables need to be flexed every time that a card is added or removed from the system. A backplane does not suffer from this problem, so its service life is limited only by the longevity of its connectors.
For example, DIN 41612 connectors have three durability grades built to withstand 50, 400 and 500 insertions and removals, or "mating cycles". To transmit information, Serial Back-Plane technology uses a low-voltage differential signaling transmission method for sending information. In addition, there are bus expansion cables which will extend a computer bus to an external backplane located in an enclosure, to provide more or different slots than the host computer provides; these cable sets have a transmitter board located in the computer, an expansion board in the remote backplane, a cable between the two. Backplanes have grown in complexity from the simple Industry Standard Architecture or S-100 style where all the connectors were connected to a common bus. Due to limitations inherent in the Peripheral Component Interconnect specification for driving slots, backplanes are now offered as passive and active. True passive backplanes offer no active bus driving circuitry. Any desired arbitration logic is placed on the daughter cards.
Active backplanes include chips. The distinction between the two isn't always clear, but may become an important issue if a whole system is expected to not have a single point of failure. A passive backplane if it is single, is not considered a SPOF. Active backplanes are more complicated and thus have a non-zero risk of malfunction; when a backplane is used with a plug-in single board computer or system host board, the combination provides the same functionality as a motherboard, providing processing power, memory, I/O and slots for plug-in cards. While there are a few motherboards that offer more than 8 slots, the traditional limit. In addition, as technology progresses, the availability and number of a particular slot type may be limited in terms of what is offered by motherboard manufacturers. However, backplane architecture is somewhat unrelated to the SBC technology plugged into it. There are some limitations to what can be constructed, in that the SBC chip set and processor have to provide the capability of supporting the slot types.
In addition an unlimited number of slots can be provided with 20, including the SBC slot, as a practical though not an absolute limit. Thus, a PICMG backplane can provide any number and any mix of ISA, PCI, PCI-X, PCI-e slots, limited only by the ability of the SBC to interface to and drive those slots. For example, an SBC with the latest i7 processor could interface with a backplane providing up to 19 ISA slots to drive legacy I/O cards; some backplanes are constructed with slots for connecting to devices on both sides, are referred to as midplanes. This ability to plug cards into either side of a midplane is useful in larger systems made up of modules attached to the midplane. Midplanes are used in computers in blade servers, where server blades reside on one side and the peripheral and service modules reside on the other. Midplanes are popular in networking and telecommunications equipment where one side of the chassis accepts system processing cards and the other side of the chassis accepts network interface cards.
Orthogonal midplanes connect vertical cards on one side to horizontal boards on the other side. One common orthogonal midplane connects many vertical telephone line cards on one side, each one connected to copper telephone wires, to a horizontal communications card on the other side. A "virtual midplane" is an imaginary plane between vertical cards on one side that directly connect to horizontal boards on the other side; some people use the term "midplane" to describe a board that sits between and connects a hard drive hot-swap backplane and redundant power supplies. Servers have a backplane to attach hot swappable hard drives, they may have single connector to connect one disk array controller or multiple connectors that can be connected to one or more controllers in arbitrary way. Backplanes are found in disk enclosures, disk arrays, servers. Backplanes for SAS and SATA HDDs most use the SGPIO protocol as means of communication between the host adapter and the backplane. Alternatively SCSI Enclosure Services can be used.
With Parallel SCSI subsystems, SAF-TE is used. A single-board computer meeting the PICMG 1.3 specification and compatible with a PICMG 1.3 backplane is referred to as a System Host Bo