Replied on May 12, Hi Eric, We regret the inconvenience caused.
Key switches[ edit ] In the first electronic keyboards in the early s, the key switches were individual switches inserted into holes in metal frames. The most popular switch types were reed switches contacts enclosed in a vacuum in a glass capsule, affected by a magnet mounted on the switch plunger.
This became more acceptable, however, for use in computer terminals at the time, which began to see increasingly shorter model lifespans as they advanced. As the key was depressed, the capacitance between the plunger pad and the patterns on the PCB below changed, which was detected by integrated circuits IC.
These keyboards were claimed to have the same reliability as the other "solid-state switch" keyboards such as inductive and Hall-effect, but competitive with direct-contact keyboards.
Meanwhile, IBM made their own keyboards, using their own patented technology: Keys on older IBM keyboards  were made with a "buckling spring" mechanism, in which a coil spring under the key buckles under pressure from the user's finger, triggering a hammer that presses two plastic sheets membranes with conductive traces together, completing a circuit.
This produces a clicking sound and gives physical feedback for the typist, indicating that the key has been depressed. Over time, less key travel was accepted in the market, finally landing on 0. Coincident with this, Key Tronic was the first company to introduce a keyboard that was only about one inch thick.
And now keyboards measure only about a half-inch thick. Keytops are an important element of keyboards. In the beginning, keyboard keytops had a "dish shape" on top, like typewriters before them.
Keyboard key legends must be extremely durable over tens of millions of depressions, since they are subjected to extreme mechanical wear from fingers and fingernails, and subject to hand oils and creams, so engraving and filling key legends with paint, as was done previously for individual switches, was never acceptable.
So, for the first electronic keyboards, the key legends were produced by two-shot or double-shot, or two-color moldingwhere either the key shell or the inside of the key with the key legend was molded first, and then the other color molded second.
But, to save cost, other methods were explored, such as sublimation printing and laser engravingboth methods which could be used to print a whole keyboard at the same time. Initially, sublimation printing, where a special ink is printed onto the keycap surface and the application of heat causes the ink molecules to penetrate and commingle with the plastic modules, had a problem because finger oils caused the molecules to disperse, but then a necessarily very hard clear coating was applied to prevent this.
Coincident with sublimation printing, which was first used in high volume by IBM on their keyboards, was the introduction by IBM of single-curved-dish keycaps to facilitate quality printing of key legends by having a consistently curved surface instead of a dish.
But one problem with sublimation or laser printing was that the processes took too long and only dark legends could be printed on light-colored keys.
On another note, IBM was unique in using separate shells, or " keycaps ", on keytop bases. This might have made their manufacturing of different keyboard layouts more flexible, but the reason for doing this was that the plastic material that needed to be used for sublimation printing was different from standard ABS keytop plastic material.
This was possible because of molding techniques that could provide very tight tolerances for the switch-plunger holes and guides across the width of the keyboard so that the key plunger-to-housing clearances were not too tight or too loose, either of which could cause the keys to bind.
The use of contact-switch membrane sheets under the monoblock. This technology came from flat-panel switch membraneswhere the switch contacts are printed inside of a top and bottom layer, with a spacer layer in between, so that when pressure is applied to the area above, a direct electrical contact is made.
The membrane layers can be printed by very-high volume, low-cost "reel-to-reel" printing machines, with each keyboard membrane cut and punched out afterwards. Plastic materials played a very important part in the development and progress of electronic keyboards.
Until "monoblocks" came along, GE's "self-lubricating" Delrin was the only plastic material for keyboard switch plungers that could withstand the beating over tens of millions of cycles of lifetime use. Greasing or oiling switch plungers was undesirable because it would attract dirt over time which would eventually affect the feel and even bind the key switches although keyboard manufacturers would sometimes sneak this into their keyboards, especially if they could not control the tolerances of the key plungers and housings well enough to have a smooth key depression feel or prevent binding.
But Delrin was only available in black and white, and was not suitable for keytops too softso keytops use ABS plastic. However, as plastic molding advanced in maintaining tight tolerances, and as key travel length reduced from 0.
Control processor[ edit ] Scanning procedure Computer keyboards include control circuitry to convert key presses into key codes  usually scancodes that the computer's electronics can understand.
The key switches are connected via the printed circuit board in an electrical X-Y matrix where a voltage is provided sequentially to the Y lines and, when a key is depressed, detected sequentially by scanning the X lines.
The first computer keyboards were for mainframe computer data terminals and used discrete electronic parts. The first keyboard microprocessor was introduced in by General Instruments, but keyboards have been using the single-chip microcontroller variant since it became available in Online French keyboard to type a text with the special characters (letters with a diacritic).
List of degree sign symbols and alt codes, including degree celsius, degree fahrenheit and kelvin signs text with letter and number. The keyboard provides a balanced distribution of typing effort between the hands: 49% for the left hand and 51% for the right. Turkish-F keyboard Afghanistan / Iran .
sign (sīn) n. 1. Something that suggests the presence or existence of a fact, condition, or quality: A high temperature is a sign of fever.
2. a. An act or gesture used to convey an idea, a desire, information, or a command: gave the go-ahead sign. See Synonyms at gesture. b. Sign language. 3. a. A displayed structure bearing lettering or symbols, used. Translit GR is a free online LatinGreek and Greeklish transliteration converter.
It includes a virtual Hellenic keyboard and spell checker. If you currently use a UK keyboard, you will probably find the UK extended keyboard the easiest way to type French accents. The keyboard layout will be maintained, but you can type most accents with the AltGr key, which is located to the right of the spacebar..
To type accent grave (à, è, etc), type ` (to the left of 1) then the vowel.