What Are Output Devices?

An output device is a terminal device of a computer hardware system. It is used to receive computer data for output display, printing, sound, and control of peripheral device operations. It also displays various calculation results data or information in the form of numbers, characters, images, sounds, and so on. Common output devices are monitors, printers, plotters, video output systems, voice output systems, magnetic recording devices, and so on.

Chinese name: Output device
Foreign name: Output Device

Attributes: Device that outputs data and information to a computer
Major equipment: Display, printer, audio, etc.

The role of output devices

The output device is a general term for a device that sends external world information to a computer and a device that returns processing results to the external world. These returned results may be used as a visual experience for the user or as input to other devices controlled by the computer: for a robot, the output of the control computer is basically the robot itself, such as performing various actions .

Output device functions

The function of the output device is to output the information processed by the computer in the memory in a form acceptable to humans or other devices.

Type of output device

There are many types of output devices. Common output devices for computers include various printers, chisel output devices, display devices, and plotters. Printers and display devices have become a necessity for every computer and most terminals.

Paper tape hole output machine Computer paper tape hole output device. Computer output is represented by small holes in a punched tape. This can not only save the information on the paper tape for a long time, but also use the perforated paper tape to enter the computer.

Card punch output machine Computer card punch output device. Punching cards are easy to read, can be stored for a long time, and can also be used as computer input.

Output device classification

Output device display

Black and white display Display is also called monitor, which is the main tool for human-machine dialogue. It can display both the commands or data entered by the keyboard, and the results of computer data processing.

There are two main types of commonly used displays. One is a CRT (Cath-odeRayTube, cathode ray tube) display for general desktop computers; the other is a Liquid Crystal Display (LCD) display for portable computers. The following mainly introduces CRT displays. According to color, it can be divided into monochrome (black and white) display and color display.

Color displays are also called graphic displays. It has two basic working modes: character mode and graphic mode. In character mode, the display content is in standard characters. The glyph of the character is composed of dot matrix. The character dot matrix is stored in the glyph generator. In the graphic mode, the display content is in pixels, and each point (pixel) on the screen can be controlled by the program's brightness and color, so it can display higher quality graphics or images.

The resolution of the display is divided into high, medium and low. The resolution index is expressed by the product of the number of pixels per line on the screen and the number of lines per frame (each screen frame). The larger the product, that is, the smaller the pixels, the larger the number, the higher the resolution, and the clearer and more beautiful the graphics.

Display adapter

Color display The display adapter, also known as the display controller, is the interface between the display and the host. It is inserted into the motherboard with a hardware card. The resolution of the display depends not only on the cathode ray tube itself, but also on the logic circuit of the display adapter. Commonly used adapters are:

(1) CGA (ColourGraphicAdapter) color graphics adapter, commonly known as CGA card, suitable for low-resolution color and monochrome displays. The display modes it supports are:

In character mode, 40 columns × 25 rows, 80 columns × 25 rows, 4 colors or 2 colors.

In graphic mode, 320 × 200, 4 colors; 640 × 200, 2 colors.

(2) EGA (EnhancedGraphicAdapter) enhanced graphics adapter, commonly known as EGA card, is suitable for medium-resolution color graphics display. It supports the display modes: 80 × 25 columns in character mode, 640 × 350, 16 colors in 256-color graphics mode

Super EGA card, support 800 × 600, 16 colors.

(3) VGA (VideoGraphicArray) video graphics array,

LCD Monitor Commonly known as VGA card, suitable for high-resolution color graphics display. The standard resolution is 640 × 480 with 256 colors. Most used are enhanced VGA cards, such as SuperVGA cards, with resolutions of 800 × 600, 1024 × 768, etc., with 256 colors.

(4) Chinese display adapter

In the process of developing the Chinese character system, China has developed some display adapters that support Chinese characters, such as GW-104 card, CEGA card, CVGA card, etc., to solve the problem of fast display of Chinese characters.

Output device printer

printer A printer is an output device that prints the processing results of a computer on paper. People often refer to the output of a monitor as a soft copy and the output of a printer as a hard copy. A device that converts computer output data into printed fonts. From the perspective of use can be divided into two categories. One type has keyboard input function, which is slower, but has the ability to talk with the computer. It is inexpensive, and in addition to computers and terminals, communication systems also use it as conventional equipment. The other type has no keyboard input function. These printers can be divided into strip printers, narrow line printers, serial printers, line printers, and page printers. According to the physical structure, the printer can be divided into two types of impact type and non-impact type.

Printer classification

According to the transmission mode, it can be divided into character printers that print one character at a time, line printers that print one line at a time, and page printers that print one page at a time.

According to the working mechanism, it can be divided into impact printers and non-impact printers. The impact type is divided into word mode printer and dot matrix printer. Non-impact type is divided into inkjet printer, laser printer, thermal printer and electrostatic printer.

printer The most commonly used microcomputers are dot-matrix printers. Dot matrix dot matrix printer features: simple structure, small size, low price, unlimited character types, low print media requirements, and can print multi-layer media. Structure: print head and carriage; paper feeding mechanism; ribbon mechanism; controller: similar to display controller. There are several needles installed on the print head. When printing, you can control the different needles to print the paper through the ribbon to get the corresponding characters and graphics. Therefore, it is often called a dot matrix printer. Most of the 9-pin or 24-pin printers used daily, mainly 24-pin printers.

Inkjet printers and laser printers are also widely used. The inkjet type is to control the deflection of a very fine ink beam through a magnetic field, and to control whether the ink is sprayed or not, and the corresponding characters or graphics can be obtained. The laser type is based on the principle of electrophotography. The controlled laser beam is irradiated onto the surface of the photosensitive drum, and different thicknesses of carbon powder are adsorbed at different positions. The corresponding characters or graphics are printed on the paper through the action of temperature and pressure. It is very similar to the way of an electrostatic copier. The laser printer has a high resolution, and the printed characters are clear and beautiful, but the price is high.

Inkjet Printers

Inkjet printers are similar to printers that use ink to write, which can directly eject ink onto ordinary paper to achieve printing, such as ejecting multiple colors of ink to achieve color hard copy output.

There are two types of inkjet printers, continuous and random. Most of the printers currently on the market use random inkjet. The early inkjet printers and the current large format printers used continuous inkjet technology.

Laser printer performance

The printing resolution of ordinary laser printers can reach 300DPI (300 dots per inch) or 400DPI, or even 600DPI. Especially for Chinese characters or graphics / image output, it is an ideal output device.

Laser printers are called "page output devices" and are expressed by pages per minute (PPM). The high speed is above 100PPM and the medium speed is 30 ~ 60PPM. They are mainly used in large computer systems. Low speed is 10 ~ 20PPM, even below 10PPM, mainly used in office automation systems and text editing systems. ^[1]

Thermal transfer printer

The printing quality of thermal transfer printers is better than that of dot-matrix dot matrix printers. It is equivalent to inkjet printers, and the printing speed is faster. Generally, the string type can exceed 6 pages / minute, and the resolution reaches 360DPI.

Printing principle

The printing head in a thermal transfer printer is a thin film head made of semiconductor integrated circuit technology. The head has a heating resistor. It consists of a thin film material that can withstand high power density and high temperature.

The thermal transfer ink is coated on the polyester base film to form a thermal transfer ribbon, which is located between the thermal printing head and the recording paper. During printing, the pulse signal heats the heating resistor in the printing head to several hundred degrees (such as 300 ° C), and the printing head is pressed on the polyester film, which melts the ink on the film base and transfers it to the recording paper, leaving a color point Color points make up characters, graphics or images. ^[1]

If printing Chinese characters, for a printer equipped with a Chinese character library, it can be printed directly.

printer Fast printing speed. If there is no Chinese character library, the Chinese character driver of the printer needs to be installed in the microcomputer. Using the Chinese character library of the computer, the printing speed is slower.

Way of working

The printer has two working modes: online and offline. The so-called connection is to connect with the host computer and be able to receive and print the information transmitted by the host computer. The so-called offline is to cut off the connection with the host. In the offline state, self-test or automatic feed / eject can be performed. These two states are controlled by the online keys on the printer panel.

Printer controller

The printer controller is also called the printer adapter, which is the control mechanism of the printer. It is also the interface between the printer and the host. It is inserted into the host board in the form of a hardware card. The standard interface is a parallel interface, which can transmit multiple data at the same time, which is faster than the serial interface.

Output device plotter

Plotter Automatic plotter is a drawing device that is directly controlled by an electronic computer or digital signal to automatically output various graphics, images and characters. Can work online or offline. It is a kind of peripheral equipment widely used in computer-aided drawing and computer-aided design. Common drawing methods are divided into tracking plotters (such as pen plotters) and scanning plotters (such as electrostatic scanning plotters, laser scanning plotters, inkjet scanning plotters) and so on. According to the mechanical structure, it can be divided into two types: drum type (drum type) plotter and desktop plotter. The transmission method of the CNC drawing machine is steel wire or steel belt drive; ball screw or rack and pinion drive; motor drive, such as linear stepper motor with open loop control and servo motor with closed loop control. A device that can automatically draw graphics according to people's requirements. It can output the output information of the computer in the form of graphics. It can mainly draw various management charts and statistical diagrams, geodetic maps, architectural design diagrams, circuit wiring diagrams, various mechanical diagrams and computer-aided design diagrams. The most commonly used is an XY plotter. Modern plotters have intelligent functions. They have a microprocessor, and can use drawing commands. They have functions such as straight line and character calculation processing, and self-testing. This plotter can also be optionally equipped with a variety of standard interfaces for connection to a computer.

A plotter is a hard copy device that outputs graphics. Plotter draws complex and accurate graphics with the support of drawing software, which is an indispensable tool for various computer-aided design. The performance indicators of the plotter mainly include the number of drawing pens, paper size, resolution, interface form, and drawing language.

Plotter The plotter is generally composed of a drive motor, an interpolator, a control circuit, a drawing table, a pen holder, and a mechanical transmission. In addition to the necessary hardware equipment, the plotter must be equipped with rich drawing software. Only software and hardware can be combined to achieve automatic drawing.

There are many types of plotters. According to the structure and working principle, they can be divided into two types: drum type and flat table type: roller type plotters. When the X-direction stepping motor drives the drum to rotate through the transmission mechanism, the sprocket drives the drawing to move, thereby achieving X-direction movement. The movement in the Y direction is realized by the pen holder driven by the Y stepping motor. This plotter has a compact structure and a large drawing area. But it requires special drawing paper with chain holes on both sides. Platform plotter. The drawing platform is provided with a beam, the pen holder is installed on the beam, and the drawing paper is fixed on the platform. The X-direction stepping motor drives the beam along with the pen holder to move in the X direction; the Y-direction stepping motor drives the pen holder to move along the beam guide in the Y direction. There are three ways to fix drawings on the platform, namely vacuum adsorption, electrostatic adsorption and magnetic strip compaction. The platform type plotter has high drawing accuracy, has no special requirements for drawing paper, and is widely used.

Development prospects of output equipment

Output device

The output devices of the first generation computers were very limited. The usual input device is a card reader for punching cards to import instructions and data into memory; the output device for storing results is usually a tape. With the advancement of science and technology, the richness of input and output equipment has been improved. Take a personal computer as an example: the keyboard and mouse are the main tools for users to directly input information into the computer, while the display, printer, amplifier, and headset return the processing results. In addition, there are many input devices that can accept different kinds of information, such as digital cameras that can input images. Among the input and output devices, two types are worth noting: the first type is secondary storage devices, such as hard disks, optical discs, or other devices that are slow but have high capacity. The second is computer network access equipment. Direct data transfer between computers through them has greatly enhanced the value of computers. The Internet has enabled tens of millions of computers to transfer various types of data to each other.