computer input devices



INPUT DEVICES

They are the ones that send information to the processing unit, in binary code. Input devices (among others):



Keyboard: A keyboard is composed of a series of keys grouped into functions that we can describe:

Alphanumeric keyboard: it is a set of 62 keys among which are the letters, numbers, orthographic symbols, Enter, alt ... etc.

Keyboard Function: is a set of 13 keys between which are the ESC, so used in computer systems, plus 12 function keys. These keys are usually configurable but for example there is an agreement to assign help to F1.

Numeric Keypad: it is usually found to the right of the alphanumeric keyboard and consists of the numbers as well as an Enter and the numerical operators of addition, subtraction, ... etc.

Special keyboard: they are the directional arrows and a set of 9 keys grouped in 2 groups; one of 6 (Start and end among others) and another of 3 with the screen print key between them.

Recommendations: In this section it is convenient to dist between two types of keyboard:

Membrane: They were the first ones that came out and as their own name indicates they present a membrane between the key and the circuit that makes the pulsation a bit harder.

Mechanic: These new keyboards present another system that makes the pulsation less traumatic and smoother for the user.

 MOUSE: This peripheral was named for its resemblance to this rodent. They are usually constituted by a box with a more or less anatomical shape in which there are two buttons that will make the famous mouse clicks being transmitted by the cable to the PS / II port or the serial port (COM1 normally). Inside this box there is a ball that protrudes from the box to which 4 orthogonally arranged rollers are attached that will define the direction of movement of the mouse. The mouse is moved by a mat causing the movement of the ball which in turn causes the movement of one or several of these rollers that is transformed into electrical signals and produce the effect of moving the mouse on the computer screen.

There are modern models in which transmission is done by infrared eliminating the need for wiring. Others present the ball in the upper part of the box, thus not being in contact with the mat and having to be moved by the user's fingers although the same effect is produced.

 Microphone: Peripheral by which transmits sounds that the computer captures and reproduces them, saves them, etc. It connects to the sound card.

Scanner: A device uses a light beam to detect the light and dark patterns (or colors) of the paper surface, converting the image into digital signals that can be manipulated by means of an image processing software or with recognition optical character. One type of scanner used frequently is the flatbed, which means that the scanning device travels along a fixed document. In this type of scanner, such as office photocopiers, objects are placed face down on a smooth glass surface and are swept by a mechanism that passes underneath them. Another type of flatbed scanner uses a scanning element installed in a fixed housing on top of the document.

A very popular type of scanner is the hand scanner, also called hand-held, because the user holds the scanner by hand and moves it over the document. These scanners have the advantage of being relatively cheap, but are somewhat limited because they can not read documents with a width greater than 12 or 15 centimeters.

Barcode Reader: a device that uses a laser beam to read drawings formed by bars and parallel spaces, which encodes information by relative widths of these elements. Bar codes represent data in a computer readable form, and are one of the most efficient means of automatic data collection.

Digital camera: Camera that connects to the computer and transmits the images it captures, which can be modified and retouched, or taken again in case it is wrong. There can be several types:

Digital photo camera: Take photos with digital quality, almost all incorporate an LCD screen (Liquid Crystal Display) where you can see the image obtained. It has a small memory where it stores photos and then transmits them to a computer.

 Video camera: Record videos as if it were a normal camera, but the advantages offered by being in digital format, which is much better the image, has an LCD screen through which you simultaneously see the image while recording. It connects to the PC and it collects the video you have recorded, so you can retouch it later with the appropriate software.

Webcam: It is a camera of small dimensions. It's just the camera, it does not have an LCD. It has to be connected to the PC in order to work, and it transmits the images to the computer. Its use is usually for video conferencing over the Internet, but using the appropriate software, you can record videos like a normal camera and take still photos.

Optical Pen: pointing device that allows to hold on the screen a pencil that is connected to the computer and with which it is possible to select elements or options (the equivalent of a mouse or mouse click), or by pressing a button on the side of the stylus or pressing it against the surface of the screen.

The pen contains light sensors and sends a signal to the computer each time it registers a light, for example when touching the screen when the non-black pixels under the tip of the pen are refreshed by the electron beam of the screen. The computer screen does not illuminate in its entirety at the same time, but the electron beam that illuminates the pixels travels them line by line, all in a space of 1/50 of a second. By detecting the moment when the electron beam passes under the tip of the stylus, the computer can determine the position of the pencil on the screen. The stylus does not require a special screen or coating, such as a touch screen, but it has the disadvantage that holding the stylus against the screen for long periods of time tires the user.

JOYSTICK: well-known pointing device, used mostly for computer or computer games, but which is also used for other tasks. A joystick or game lever usually has a round or rectangular plastic base, to which a vertical lever is attached. The control buttons are located on the base and sometimes on the top of the lever, which can be moved in all directions to control the movement of an object on the screen. The buttons activate various software elements, usually producing an effect on the screen. A joystick is usually a relative pointing device, which moves an object on the screen when the lever moves with respect to the center and which stops movement when released. In industrial control applications, the joystick can also be an absolute pointing device, in which a specific location is marked on the screen with each position of the lever.

Perforated cards: Manila sheet of 80 columns, about 7.5 cm. (3 inches) wide by 18 cm. (7 inches) long, in which 80 columns of data could be introduced in the form of holes made by a drilling machine. These holes corresponded to numbers, letters and other characters that could be read by a computer equipped with a punched card reader.

 Touch screen: screen designed or modified to recognize the situation of a pressure on its surface. By touching the screen, the user can make a selection or move the cursor. The simplest touch screen type is composed of a network of sensitive lines, which determine the situation of a pressure by joining the vertical and horizontal contacts.

Other types of more accurate screens use an electrically charged surface and sensors around the outer edges of the screen, to detect the amount of electrical change and pinpoint exactly where the contact has been made. A third type fixed infrared emitting diodes (LEDs, acronym for Light-Emitting Diodes) and sensors around the outer edges of the screen. These LEDs and sensors create an invisible infrared network in the front of the screen that interrupts the user with his fingers.

Infrared touch screens are often used in dirty environments, where dirt could interfere with the operation mode of other types of touch screens. The popularity of touch screens among users has been limited because it is necessary to keep your hands in the air to point the screen, which would be too uncomfortable in long periods of time. It also does not offer great precision when having to point out certain elements in high resolution programs. Touch screens, however, are hugely popular in applications such as information booths because they offer a way of pointing out that it does not require any mobile hardware and because pressing the screen is intuitive.