hardware

2009年2月28日星期六

bluetooth dongle headset

This article is about the electronic protocol. For the medieval King of Denmark, see Harald I of Denmark.

Bluetooth logo.
Bluetooth is a wireless protocol for exchanging data over short distances from fixed and mobile devices, creating personal area networks (PANs). It was originally conceived as a wireless alternative to RS232 data cables. It can connect several devices, overcoming problems of synchronization.

Origin of the name
The word "Bluetooth" is an Anglicized version of the name of a tenth-century king, Harald Blaatand, king of Denmark and Norway, who united dissonant Scandinavian tribes into a single kingdom. The implication being that Bluetooth does the same with communications protocols, uniting them into one universal standard.
It is possible that the name may have been inspired less by the historical Harald, than by the loose interpretation of him in The Long Ships by Frans Gunnar Bengtsson, a Swedish Viking-inspired novel.

Origin of the Bluetooth logo
The Bluetooth logo design merges the Germanic runes analogous to the modern Latin letters H and B: (for Harald Bluetooth) (Hagall) and (Berkanan) merged together, forming a bind rune.

Implementation
Bluetooth uses a radio technology called frequency-hopping spread spectrum, which chops up the data being sent and transmits chunks of it on up to 79 frequencies. In its basic mode, the modulation is Gaussian frequency-shift keying (GFSK). It can achieve a gross data rate of 1 Mb/s. Bluetooth provides a way to connect and exchange information between devices such as mobile phones, telephones, laptops, personal computers, printers, Global Positioning System (GPS) receivers, digital cameras, and video game consoles through a secure, globally unlicensed Industrial, Scientific, and Medical (ISM) 2.4 GHz short-range radio frequency bandwidth. The Bluetooth specifications are developed and licensed by the Bluetooth Special Interest Group (SIG). The Bluetooth SIG consists of companies in the areas of telecommunication, computing, networking, and consumer electronics.

Uses
Bluetooth is a standard and communications protocol primarily designed for low power consumption, with a short range (power-class-dependent: 1 meter, 10 meters, 100 meters) based on low-cost transceiver microchips in each device. Bluetooth makes it possible for these devices to communicate with each other when they are in range. Because the devices use a radio (broadcast) communications system, they do not have to be in line of sight of each other.

In most cases the effective range of class 2 devices is extended if they connect to a class 1 transceiver, compared to a pure class 2 network. This is accomplished by the higher sensitivity and transmission power of Class 1 devices.

bluetooth dongle headset

Remote Control Keyboard

Flexible Silicone Keyboard

Toyota Landcruiser Prado

Used Laser Printer

TFT LCD Monitor

Stand Alone Monitors

ir wireless headphone

Headphones are a pair of small loudspeakers, or less commonly a single speaker, with a way of holding them close to a user's ears and a means of connecting them to a signal source such as an audio amplifier, radio or CD player. They are also known as earphones, earbuds, stereophones, headsets or, informally cans. In the context of telecommunication, the term headset is used to describe a combination of headphone and microphone used for two-way communication, for example with a telephone.

History

Old telephone earpiece
The telephone earpiece such as the one pictured at the right was common around the turn of the 20th century. From the earpiece developed the headphones. Sensitive headphones were the only way to listen to audio signals before amplifiers were developed.

Brandes radio headphones, circa 1920
Very sensitive headphones such as those manufactured by Brandes around 1919 were commonly used for early radio work. These early headphones used moving iron drivers, either single ended or balanced armature. The requirement for high sensitivity meant no damping was used, thus the sound quality was crude. They also had very poor comfort compared to modern types, usually having no padding and too often having excessive clamping force to the head. Impedance varied, but 1,000 to 2,000 ohms was common, which suited both triodes and crystal sets.
When used with early powered radios, the headphone was normally connected to the positive high voltage battery terminal, and the other battery terminal was securely earthed. The use of bare electrical connections meant that users could be shocked if they touched the bare headphone connections while adjusting an uncomfortable headset.

Applications
Headphones can be used both with fixed equipment such as CD or DVD players, home theater, personal computers and with portable devices (e.g. digital audio player/mp3 player, mobile phone, etc.). Cordless headphones do not need to be connected via a wire, receiving a radio or infrared signal encoded using a radio or infrared transmission link, like FM, Bluetooth or Wi-Fi. These are actually made of powered receiver systems of which the headphone is only a component, these types of cordless headphones are being used more frequently with events such as a silent disco or Silent Gig.
Headphones are widely used for listening to audio sources for recreation. In the professional audio sector headphones are used in live situations by disc jockeys with a DJ mixer and sound engineers for monitoring signal sources. In radio studios, DJs use a pair of headphones when talking to the microphone while the speakers are turned off, to eliminate acoustic feedback and monitor their own voice. In studio recordings, musicians and singers use headphones to play along to a backing track. In the military, audio signals of many varieties are monitored using headphones.
Wired headphones are attached to an audio source. The most common connectors are 1/4" and 3.5 mm stereophonic jack plugs and sockets. The older 1/4" standard is used on professional equipment, and is often used on fixed equipment. Sony introduced the smaller, cheaper, and now widely-used, 3.5 mm "mini" stereo connector in 1979, adapting the older monophonic 3.5 mm connector for use with its Walkman portable stereo tape player. Adapters are available for converting between 1/4" and 3.5 mm devices.

Types of headphones
There are many different types of headphone designs, with the listening situation and the needs of the listener determining what type of headphone will be used. Generally, headphone formfactors can be divided into four separate categories: circumaural, supra-aural, earbud, and in-ear.

Earcup headphones
Earcup or on-ear headphones rest on the exterior of the ear and were the earliest headphone form designed.
The housing, or earcup, of an earcup headphone will be either open or closed. Open headphones, sometimes marketed as “open air” headphones, have an open grille on the back of the earcup, exposing the driver to the outside and allowing sound waves to propagate away from the ear freely. This backing type does not isolate the listener from outside sounds; in addition, sound through open headphones can be heard by others in the vicinity of the user. They usually have less distortion due to the lack of earcup resonance. Closed headphones have a sealed backing, which attenuates sound waves propagating away from the ear. As a result, listeners away from the headphones cannot hear the produced sound easily. In addition, sound from outside is attenuated by the sealed backing, providing a level of isolation to the listener. A sealed chamber is often claimed to have the negative effect of distorting sound in certain frequencies due to resonances within the earcup housing, however, bass frequencies are stronger in a sealed chamber headphone design.

Circumaural
Circumaural headphones (sometimes called fullsized headphones) have circular or

ellipsoid earpads that completely surround around the ears. This type of headphone is commonly used in recording studios and among audio enthusiasts.

Supra-aural
Supra-aural headphones have pads that sit on top of the ears, rather than around them. They were commonly bundled with personal stereos during the 1980s.

Earbuds

Earbuds or earphones, such as these that ship with the Apple's iPod, rest in the outer part of the ear canal.

Canalphones extend into the ear canal, facilitating greater dynamic range than earbuds as well as isolation from outside noise.
Earbuds or earphones are headphones of a smaller size that are placed directly outside of the ear canal, but without fully enveloping it. They are generally inexpensive and are favored for their portability and convenience. However, due to their inability to provide isolation, they are not capable of delivering the same dynamic range offered by many full-sized headphones and canalphones for a given volume level. As a result, they are often used at higher volumes in order to drown out noise from the user's surroundings, which increases the risk of hearing-loss.During the 1990s and 2000s, earbuds became a common type bundled with personal music devices.

ir wireless headphone

bluetooth dongle headset

Remote Control Keyboard

Flexible Silicone Keyboard

Toyota Landcruiser Prado

Used Laser Printer

TFT LCD Monitor

Pen USB Disk

A pen (Latin pinna, feather) is a writing instrument used to apply ink to a surface, usually paper. There are several different types, including ballpoint, rollerball, fountain, felt-tip. Historically, reed pens, quill pens, and dip pens were used.

Types
The main modern types can be categorized by the kind of writing tip:
A ballpoint pen dispenses viscous oil-based ink by rolling a small hard sphere, usually 0.7–1.2 mm and made of brass, steel or tungsten carbide. It automatically sends ink out from a little ball.The ink dries almost immediately on contact with paper. This type of pen is generally inexpensive and reliable. It has replaced the fountain pen as the most popular tool for everyday writing.
A rollerball pen dispenses a water-based liquid or gel ink through a ball tip similar to that of a ballpoint pen. The less-viscous ink is more-easily absorbed by paper than oil-based ink, and the pen moves more easily across a writing surface. The rollerball pen was initially designed to combine the convenience of a ballpoint pen with the smooth "wet ink" effect of a fountain pen. Gel inks are available in a range of colors, including metallic paint colors and glitter effects.

A letter written on paper with a rollerball pen, and the tip of that pen
A fountain pen uses water-based liquid ink delivered through a nib. The ink flows from a reservoir through a "feed" to the nib, then through the nib, due to capillary action and gravity. The nib has no moving parts and delivers ink through a thin slit to the writing surface. A fountain pen reservoir can be refillable or disposable, this disposable type being an ink cartridge. A pen with a refillable reservoir may have a mechanism, such as a piston, to draw ink from a bottle through the nib, or it may require refilling with an eyedropper. Refillable reservoirs are available for some pens designed to use disposable cartridges.
A felt-tip pen, or marker, has a porous tip of fibrous material. The smallest, finest-tipped markers are used for writing on paper. Medium-tip markers are often used by children for coloring. Larger markers are used for writing on other surfaces such as cardboard boxes and whiteboards. Markers with wide tips and bright but transparent ink, called highlighters, are used to mark existing text. Markers designed for children or for temporary writing (as with a whiteboard or overhead projector) typically use non-permanent inks. Large markers used to label shipping cases or other packages are usually permanent markers.

These historic types of pens are no longer in common use:
A dip pen (or nib pen) consists of a metal nib with capillary channels, like that of a fountain pen, mounted on a handle or holder, often made of wood. A dip pen usually has no ink reservoir and must be repeatedly recharged with ink while drawing or writing. The dip pen has certain advantages over a fountain pen. It can use waterproof pigmented (particle-and-binder-based) inks, such as so-called India ink, drawing ink, or acrylic inks, which would destroy a fountain pen by clogging, as well as the traditional iron gall ink, which can cause corrosion in a fountain pen. Dip pens are now mainly used in illustration, calligraphy, and comics (notably manga).
A quill is a pen made from a flight feather of a large bird, most often a goose. Quills were used as instruments for writing with ink before the metal dip pen, the fountain pen, and eventually the ballpoint pen came into use. The shaft of the feather acts as an ink reservoir, and ink flows to the tip by capillary action. Quill pens were used in medieval times to write on parchment or paper. The quill eventually replaced the reed pen.
A reed pen is cut from a reed or bamboo, with a slit in a narrow tip. Its mechanism is essentially similar to that of a quill.

History
Ancient Egyptians had developed writing on papyrus scrolls when scribes used thin reed brushes or reed pens from the Juncus Maritimus or sea rush . In his book A History of Writing, Steven Roger Fischer suggests that on the basis of finds at Saq

qara, the reed pen might well have been used for writing on parchment as long ago as the First Dynasty or about 3000 BC. Reed pens continued to be used until the Middle Ages although they were slowly replaced by quills from about the seventh century.
The quill pen was used in Qumran, Judea to write some of the Dead Sea Scrolls, and then introduced into Europe by around 700 AD. It was used in 1787 to write and sign the Constitution of the United States of America. The Dead Sea Scrolls discovered in 1947 on the northwest bank of the Dead Sea date back to around 100 BC. At that time they were written in Hebrew dialects with bird feathers or quills. After the fall of the Roman Empire, Europeans had difficulty in obtaining reeds and began to use quills. There is a specific reference to quills in the writings of St. Isidore of Seville in the 7th century. Quill pens were used until the nineteenth century.
A bronze nib was found in the ruins of Pompei showing that metal nibs were used in the year 79. There is also a reference in Samuel Pepys' diary for August 1663. A metal pen point was patented in 1803 but the patent was not commercially exploited. John Mitchell of Birmingham started to massproduce pens with metal nibs in 1822. During the 19th century metal nibs replaced quill pens. By 1850 the quality of steel nibs had improved and dip pens with metal nibs came into generalized use.

Waterman pen and fountain pens made for Air France’s Concorde
The earliest historical record of a reservoir fountain pen dates back to the 10th century. In 953, Ma'ād al-Mu'izz, the Fatimid Caliph of Egypt, demanded a pen which would not stain his hands or clothes, and was provided with a pen which held ink in a reservoir and delivered it to the nib via gravity and capillary action.
In his Deliciae Physico-Mathematicae (1636), German inventor Daniel Schwenter described a pen made from two quills. One quill served as a reservoir for ink inside the other quill. The ink was sealed inside the quill with cork. Ink was squeezed through a small hole to the writing point.

M. Klein and Henry W. Wynne received US patent #68445 in 1867 for an ink chamber and delivery system in the handle of the fountain pen.
Quill pens began being replaced with steel dip pens in the first years of the 1800s. In Newhall Street, John Mitchell pioneered mass production of steel pens. The first fountain pens making use of all these key ingredients appeared in the 1850s. While a student in Paris, Romanian Petrache Poenaru invented the fountain pen; an invention which the French Government patented in May 1827. Starting in the 1850s there was a steadily accelerating stream of fountain pen patents and pens in production.
Slavoljub Eduard Penkala was a Croatian engineer and inventor who held over seventy patents. Slavoljub Penkala background was in chemistry, however, he is best known as the inventor of the first mechanical pencil first named the "automatic pencil", which he invented in 1906. Penkala started a factory called Penkala-Mostero for the manufacturing of his pens and pencils. http://inventors.about.com/od/pstartinventors/a/Croatian.htm
Other inventions Slavoljub Penkala was noted for was the first solid-ink fountain pen in 1907, and the first Croatian two-seat airplane in 1909. He also patented a hot water bottle, detergent, a rail-car brake, and a anode. http://inventors.about.com/od/pstartinventors/a/Croatian.htm
The first patent on a ballpoint pen was issued on October 30 1888, to John J Loud[8]. In 1938, László Bíró, a Hungarian newspaper editor, with the help of his brother George, a chemist, began to work on designing new types of pens including one with a tiny ball in its tip that was free to turn in a socket. As the pen moved along the paper, the ball rotated, picking up ink from the ink cartridge and leaving it on the paper.
Bíró filed a British patent on June 15, 1938. In 1940 the Bíró brothers and a friend, Juan Jorge Meyne, moved to Argentina fleeing Nazi Germany and on June 10, filed another patent, and formed Bíró Pens of Argentina. By the summer of 1943 the first commercial models were available. Erasable ballpoint pens were introduced by Papermate in 1979 when the Erasermate was put on the market.

Modern marker pens
In the 1960s the fibre, or felt-tipped pen was invented by Yukio Horie of the Tokyo Stationery Company, Japan. Papermate's Flair was among the first felt-tip pens to hit the U.S. market in the 1960s, and it has been the leader ever since. Marker pens and highlighters, both similar to felt pens, have become popular in recent years.
Rollerball pens were introduced in the early 1980s. They make use of a mobile ball and liquid ink to produce a smoother line. Technological advances achieved during the late 1980s and early 1990s have improved the roller ball's overall performance. A porous point pen contains a point that is made of some porous material such as felt or ceramic. A high quality drafting pen will usually have a ceramic tip, since this wears well and does not broaden when pressure is applied while writing.
Although the invention of the personal computer with the keyboard input method have changed how users write, the pen has not been entirely replaced and likely won't any time soon. Higher end pens including archaic types such as fountain pens are still a status symbol.

Pen USB Disk

ir wireless headphone

bluetooth dongle headset

Remote Control Keyboard

Flexible Silicone Keyboard

Toyota Landcruiser Prado

Used Laser Printer

overhead lcd monitor

Monitor may refer to:
Computers with technology
Visual display unit, a device that displays images generated by computers
Monitor (synchronization), an approach to synchronize two or more computer tasks that use a shared resource
Foldback (sound engineering), the use of rear-facing speakers on stage during a music performance
Machine code monitor, software allowing users to view or change memory locations on a computer
Medical monitor, automated medical device that senses and displays a patient's vital signs
Studio monitor, a loudspeaker designed for audio production applications
Supervisory control, a system that measures or controls data
Video monitor, a device that displays output from a video-generating device
Virtual Machine Monitor, software which virtualizes a computer hardware platform, allowing multiple system images to run simultaneously.
Warships
Monitor (warship), a small warship with one or several very large guns
River monitor, a class of warship used in inland waterways
USS Monitor, a United States Navy warship used during the American Civil War
USS Monitor (LSV-5) a United States Navy vehicle landing ship Companies Media and Entertainment
Monitor (BBC TV)
Monitor (comics), a DC comics character
Monitor (NBC Radio)
Republic record label
Place names
Monitor, Indiana, a town in the United States
Monitor, Oregon, an unincorporated community in the United States
Monitor, Alberta, Canada
Other meanings
Water jet used in hydraulic mining
Fire monitor, a water jet used for firefighting
Monitor (NHS), a United Kingdom government agency also known as the Independent Regulator for NHS Foundation Trusts
Monitor lizard, a lizard
Hall monitor, a student who supervises the corridors of a school
See also
The Monitor
The Monitors
Monitoring

overhead lcd monitor

Pen USB Disk

ir wireless headphone

bluetooth dongle headset

Remote Control Keyboard

Flexible Silicone Keyboard

Toyota Landcruiser Prado

PC Speaker USB

The PC speaker is the most primitive sound system used in IBM PC compatibles. It was the only source of sound available to PC games before more technologically advanced sound cards such as AdLib and Sound Blaster were introduced as ISA plug-in cards in the late 1980s. However, even some years after these sound cards became mainstream and widely used, game manufacturers continued to support speaker sound/music in their games in order to maximise their customer base. This was in part because sound cards did not originally follow any commonly agreed-upon standard and were largely incompatible with each other, whereas the PC speaker was the only sound system that could be regarded as universally present.
The PC speaker is best characterized by its inability to play more than one tone at once, the waveform being generated by the Programmable Interval Timer. Because of this, it was often nicknamed a PC beeper or PC squeaker, especially when sound cards became widely available. In spite of its limited nature, the PC speaker was often used in very innovative ways to create the impression of polyphonic music or sound effects within computer games of its era, such as the LucasArts series of adventure games from the mid-1990s, using swift arpeggios. Several programs, including MP (Module Player, 1989), ScreamTracker, Fast Tracker, Impulse Tracker, and even device drivers for Linux and Microsoft Windows, could play pulse-code modulation (PCM) sound through the PC speaker using special techniques explained later in this article. Several games such as Space Hulk and Pinball Fantasies were noted for their elaborate sound effects; Space Hulk in particular even had full speech. However, because the method used to reproduce PCM was very sensitive to timing issues, these effects either caused noticeable sluggishness on slower PCs, or sometimes failed completely on faster PCs (that is, significantly faster than the program was originally developed for).
All modern operating systems include a generic sound API, so that applications no longer need to know the specifics of each sound card. Correspondingly, the use of high-quality sound hardware has become commonplace. As a result, the PC speaker today deals mainly with low-level warning signals such as start-up errors. Regardless, the speaker's interface has remained the same and as such can still be utilized (as long as it hasn't been reduced to an onboard miniature piezo speaker, whose acoustic properties are significantly different from the older paper cone speakers such that most of the more complex sound generation techniques no longer work).
Pulse-width modulation
The PC speaker is normally meant to reproduce a square wave via only 2 levels of output, driven by channel 2 of the Intel 8253 (PC, XT) or 8254 (AT and later) Programmable Interval Timer operating in mode three (square wave signal). The speaker hardware itself is directly accessible via PC I/O port 61H (61 hexadecimal) via bit 1 and can be physically manipulated for 2 levels of output (i.e. 1-bit sound). However, by carefully timing a short pulse (i.e. going from one output level to the other and then back to the first), it is possible to drive the speaker to various output levels in between the two defined levels. This effectively allows the speaker to function as a crude DAC, thereby enabling approximate playback of PCM audio. This technique is called pulse-width modulation (PWM) and is notably used in class D audio amplifiers.
Getting a high fidelity sound output out of this technique requires the switching frequency between the minimum and maximum sound levels to be much higher than the audio frequencies meant to be reproduced (typically with a ratio of 10:1 or more), and the output voltage to be bipolar in order to make better use the output devices' dynamic range and power (e.g. by making a loudspeaker vibrate in both directions). On the PC speaker, however, the output voltage is either zero or TTL level (unipolar). As a result, the precision of this technique when used on the PC speaker is comparable at best to a 6-bit PCM DAC, while the final audio results will depend on precise timing and the nature of the reproduced sound.
The audio fidelity of this technique will be further decreased by the lack of a properly sized dynamic loudspeaker, typical of modern machines and particularly laptops, that use a piezoelectric speaker. The reason for this is that PWM-produced audio requires a low-pass filter before the final output in order to suppress switching noise and high harmonics, something that a normal dynamic loudspeaker can do on its own right, while a piezoelectric speaker will let most switching noise pass, as will many direct couplings (though there are exceptions to this, e.g. filtered "speaker in" ports on some motherboards and sound cards).
External links
Site for old PC without sound cards.
GameDev.net article on programming the PC Speaker.
Part 1 of another article about programming the PC speaker.
Part 2 of the article(includes a very detailed explanation of how to play back PCM audio on the PC speaker, and why it works)
Bleeper Music Maker A freeware to use the PC speaker to make music
Article about programming PC speaker using C++
Commandline PC speaker program for LinuxFTP

PC Speaker USB

overhead lcd monitor

Pen USB Disk

ir wireless headphone

bluetooth dongle headset

Remote Control Keyboard

Flexible Silicone Keyboard

roll up displays

Fruit Roll-Ups, a fruit snack available in the United States and Australia
Rollup, a tactic of investors where similar small companies are acquired and then merged.
Star Wars Roll-up, an alternative name for the Star Wars opening crawl
Roll-up, a kind of cigarette containing shag tobacco, hand-rolled in rolling papers
Roll-up keyboard, a keyboard that can be rolled up
Roll-away computer, a computer that can be rolled up
Roll-up, a type of pin in professional wrestling

Display may mean one of several things:
Airshow, Museum, Art exhibition, Trade fair, Science fair, Store display
Trade show display, the physical screens, banners and other paraphernalia used to fill a temporary exhibit space at a trade show or trade fair.
Display as a form of biological behaviour
Object for promotion and/or providing information, e.g. of cardboard, in a shop, movie theater, etc.; see Point-of-sale displays, Film promotion.
Display device, a device for displaying visual or tactile information
In particular, a computer display (monitor), a television screen or other electronic visual displays.
Display font - a font that is suitable for use on a computer display
Information visualization
Fireworks display
Volumetric display
A type of activation frame in a call stack utilized by programming languages

ir wireless headphone

bluetooth dongle headset

Remote Control Keyboard

Sun Visor Monitors

A sun visor is a component of an automobile located on the interior just above the windshield (also known as windscreen).
Most cars have two sun visors. One for the driver and a second for the passenger's side, with the rear-view mirror often mounted in the middle. Each visor can be lowered to help block light from the sun entering through the windshield. They can also be turned to the front side window to reduce lateral sun exposure.
Many sun visors also incorporate a vanity mirror for passenger's convenience. In some cases, a flip up cover over the mirror automatically turns on the vanity lights, which can be adjusted with a sliding dimmer control (see image).
Recently, sunvisors incorporating LCD screens, DVD players and other devices have become available as an aftermarket modification.

ir wireless headphone

bluetooth dongle headset

Remote Control Keyboard