Additional devices. Output devices One of the output devices

You can connect additional devices to your computer.

Computer output devices

Computer input devices

	This is a microphone. From microphone computer introduces sound to your memory. The microphone is an input device.
	This is a scanner. The scanner allows the computer enter texts and drawings from paper in your memory. The scanner is an input device.
	This is a joystick. A joystick is a command input device well known to gamers. The joystick is convenient to control the heroes of games on the computer screen.

Input and output devices

Information can be entered into a computer with a laser disk. And vice versa, write to disk. The computer inputs and outputs information from the disk using drive.

This is a flash drive (or just a flash drive):

It is easy to insert a USB flash drive into a computer connector:

A flash drive has memory from which a computer can enter information. On the memory of a flash drive, a computer can output information.

A flash drive is an input and output device.

And the memory of a flash drive is a device information storage:

The machine can be connected to the computer at the factory. And then the production of the product takes place without human intervention.

The machine is also an input and output device.

Commands are sent from the computer to the machine (they are output from the computer).

The computer receives information about the progress of the machine (entered into the computer).

The figure below shows an embroidery machine controlled by a computer.

Camera Video camera

The camera and camcorder have a memory card inside to store footage. The computer can enter information from the memory card of such a device and, conversely, write information to the memory card ( output). It turns out that the camera and video camera for the computer are input and output devices. And camera memory is a device information storage.

The input and output device for a computer is and mobile phone:

• output device- information on it output from a computer (monitor, printer, speakers, headphones).
• Input device- information from him introduced into a computer (mouse, keyboard, microphone, scanner, joystick).
• Input and output device- information on it output and information from it introduced(disk drive, flash drive, camera, video camera, telephone, computer-controlled machine).

After the user enters the initial data, the computer must process them in accordance with the available program and display the results obtained for their perception by the operator or for use by automatic devices. The output information can be displayed on a monitor screen, printed on paper (using a printer or plotter), played back as sounds (using speakers or headphones), registered as tactile sensations (virtual reality technology), distributed as control signals ( automation devices), transmitted in the form of electrical signals over the network.

The most common output devices are monitors (displays). The vast majority of monitors use cathode ray tubes (CRT) or liquid crystal matrices to form an image. And now there is a gradual displacement of monitors with CRT monitors using liquid crystals.

There are monitors based on other physical principles: plasma, fluorescent, etc.

For example, monitors made using FED (Field Emission Display) technology are based on the effect of creating emission over the entire surface of the screen. Unlike CRT, the source of electrons is not a single point (electron gun), but the whole radiating surface. Irradiation is performed through a mask in which the number of holes is equal to the number of pixels. Due to this design, it is possible to obtain the image brightness the same as that of CRT monitors, and the dimensions (thickness) - like those of liquid crystal monitors.

A new technology for manufacturing monitors is considered promising - OLED (Organic Light Emitting Diodes). Their design is based on the use of organic light emitting diodes.

Printers, depending on the order of image formation, are divided into sequential, line and page. The printer's belonging to one group or another depends on whether it forms character by character on paper or the entire line at once, or even the whole page.

According to the physical principle of operation, printers are divided into the following types: thermal, petal (chamomile), matrix (needle), inkjet and laser.

The design of the first two types of printers is morally obsolete, and they are practically no longer used.

AT dot matrix printers the image is formed from dots by hitting the needles on the ink ribbon. Under the action of control signals to the electromagnets, the needles "knock out" the paint from the tape, leaving traces on the paper. Depending on the design, the print head of a dot matrix printer can have 9, 18 or 24 needles. All symbols are formed from individual dots.

Printheads inkjet printers instead of needles, they contain thin tubes - nozzles through which droplets of ink are ejected onto the paper. The print head of an inkjet printer contains from 12 to 64 nozzles, the diameters of which are thinner than a human hair.

There are several principles of operation of inkjet printheads.

One design has a small ink reservoir at the inlet end of each nozzle. Behind the tank is a heater (thin film resistor). When the resistor is heated by the current passing through it to a temperature of 500 ° C, the surrounding ink boils, forming a vapor bubble. This expanding bubble pushes out ink drops with a diameter of 50...85 microns from the nozzle at a speed of about 700 km/h.

In another design of the printhead, the pressure source is a membrane driven by a piezoelectric element. Innings electrical voltage on the piezo element causes its deformation, which is used to spray ink.

In all printer designs, electromechanical devices move the printheads and paper in such a way that printing occurs in the right place.

AT laser printers the electrographic principle of image creation is used. The printing process includes the formation of an invisible relief of the electrostatic potential in the semiconductor layer with its subsequent visualization. Visualization (development) is carried out with the help of particles of dry powder - toner, applied to paper. Toner is pieces of iron coated with plastic. The most important parts of a laser printer are a semiconductor drum, a laser, and a precision optical-mechanical system that moves the beam (Fig. 10.5).

The laser generates a thin beam of light, which, reflected from a rotating mirror, forms an electronic image on a light-sensitive semiconductor drum.

Some static charge is preliminarily reported to the surface of the drum. A mesh or thin wire is used to create an electrostatic charge. When high voltage is applied to the wire, a corona discharge occurs, as a result of which a luminous ionized region of space appears around the wire. Due to the corona discharge, the surface of the drum is evenly charged. To obtain an image on the drum, the laser must be turned on and off in accordance with the image being formed, which is provided by the control circuit. The control signals come from the computer in accordance with the image stored in the memory. The rotating mirror is used to turn the laser beam into a line formed on the surface of the drum.

When a laser beam hits a pre-charged drum, the charge "flows" from the illuminated surface. Thus, the areas of the drum illuminated and unilluminated by the laser have a different charge. As a result of scanning the entire surface of the semiconductor drum, a latent (electronic, not visible to humans) image is created on it.

The rotation of the drum to a new line is carried out by a precision stepper motor. This offset determines the resolution of the printer and can be, for example, 1/300, 1/600 or 1/1200 of an inch. The process of scanning an image on a drum is in many ways similar to building an image on a monitor screen (creating a raster).

Rice. 10.5. Laser printer printing process

At the next stage of the printer's operation, the image is developed, i.e., the latent electronic image is converted into a visible one. When developing an image, the following physical phenomenon is used: charged toner particles are attracted only to those places on the drum that have the opposite charge with respect to the charge of the toner.

When the visible image on the drum is built and coated with toner according to the original, the sheet of paper being fed is charged in such a way that the toner from the drum is attracted to the paper. The adhering powder is fixed on the paper by heating the toner particles to the melting point. As a result, a waterproof imprint is formed. colored laser printers an image is formed by successively applying cyan, magenta, yellow, and black toners onto a photosensitive drum.

In a four-pass color printer, the print speed is significantly slower than in a black and white printer. In a single-pass color printer, four toner cartridges are installed in the same plane one behind the other, each next to its own ram. All colors are applied in one pass instead of four, so the speed of imaging is increased.

In addition to laser printers, there are so-called LED printers (Light Emitting Diode), which got their name due to the fact that the semiconductor laser in them is replaced by a “comb” (line) of LEDs. In this case, a complex mechanical system of mirror rotation is not needed. The image of one line on the semiconductor drum is formed at the same time.

In table. 10.1. the characteristics of printers of various designs are given.

Table 10.1. Printer Specifications

Plotters (or plotters) are graphic information output devices that are used in the design of large posters, drawings, geographical maps, circuit board sketches, diagrams, histograms.

The work of the plotter is based on mechanical and non-mechanical methods of displaying graphic information. With the mechanical method, pencils, pens with ink are used. Similar to printers, non-mechanical plotters use thermal, matrix, inkjet, and laser printing methods.

As devices capable of performing the functions of input and output of information, can be used communication adapters. With their help, communication between computers is carried out over a telephone line. Since telephone networks still work more often not with digital, but with analog electrical signals in the audio range, it is necessary to convert the digital signals coming from the computer into analog signals and transfer them to telephone network. At the other end of the telephone line, the reverse conversion must be performed. These conversions are performed by a special device - a modem (from the words MODulator - DEModulator).

The modem is made either in the form of an external device that is connected to the telephone line with one output and to a standard computer port with the other, or as an ordinary board (card) that is installed on the computer's system bus (internal modem).

The output of sound information is carried out using speakers and headphones (Fig. 10.6), which are connected through a special adapter (controller, sound card).

Rice. 10.6. Headphones

There are several ways to play sounds (particularly music). The frequency method (FM-synthesis) of sound reproduction is based on the imitation of the sound of real instruments, and the tabular method (wave-table-synthesis) operates with the sounds of real instruments recorded in memory.

Frequency synthesis is based on the fact that to obtain any sound, mathematical formulas (models) are used that describe the frequency spectrum of a particular musical instrument. The sounds obtained by this technology are characterized by a metallic tint.

Wave synthesis is based on the use of digital recording of real instruments, the so-called samples. Samples are samples of the sound of various real instruments stored in memory. sound card. When playing sounds using wave synthesis technology, the user hears the sounds of real instruments, so the created sound picture is closer to natural sound tools.

Samples can be stored in two ways: either permanently in ROM, or loaded into RAM sound card before using them. There is a large set of various samples, which allows you to create an almost endless variety of sounds.

Display (monitor) is the most popular output device. There are monochrome (black and white) and color displays. First, consider the principle of operation of black and white monitors.

Rice. 10.7. Cathode-ray tube

The main display unit is cathode ray tube (CRT). Sometimes the abbreviation CRT is used to denote a CRT - Cathode Ray Tube. One of the possible designs of the CRT is shown in Fig. 10.7.

We list the main parts that make up a CRT: cathode, anode, modulator, horizontal deflection plates, vertical deflection plates, screen, bulb.

The cathode, anode, and modulator form an electron projector, sometimes referred to as an electron gun. Horizontal and vertical deflection plates form the deflection system. Such a deflecting system is called electrostatic. There are magnetic deflection systems in which coils are used instead of plates to change the trajectory of the electron flow.

A CRT uses a stream of electrons focused into a narrow beam controlled by intensity and position in space and interacting with the tube screen. The electron beam is emitted by an electron searchlight (more precisely, a cathode), and the beam position on the screen is changed by a deflecting system.

The movement of an electron beam across the screen of a CRT in accordance with a certain law is called a scan, and the pattern traced by the trace of an electron beam on the screen is called a raster. The sweep is carried out by applying periodically changing voltages to the deflecting system of the CRT. During the sweep, the electron beam sequentially runs along the lines of the CRT screen surface.

In the process of raster formation, the electron flow moves along a zigzag path from the upper left corner of the screen to the lower right corner. On fig. 10.8 solid lines show the raster, dashed lines - the trajectory of the electron beam, on which it is "quenched" (becomes invisible).

Rice. 10.8. Raster and electron beam trajectory

The screen is covered with a phosphor, therefore, in the places where the electron beam falls, a glow appears, the brightness of which is proportional to the intensity of the beam. The intensity of the electron flow changes in accordance with the signals applied to the control electrode - modulator. It is these signals that form the desired image on the display screen.

Rice. 10.9. Image of the letter "I"

On fig. 10.9 shows a large scale image of the letter "I". In this case, it took eight lines of the raster to display it. On fig. 10.10. shows the timing diagrams for the control signals applied to the modulator. High potential corresponds to white areas of the screen, low - to black. With the help of a deflecting system, the modulated electron beam is unfolded into a raster, highlighting line by line on the screen, thus reproducing the image frame by frame. Due to the inertia of vision, a person sees a continuous, often dynamic, image on the screen.

Rice. 10.10. Timing diagrams for control signals

Any image on the monitor screen consists of a set of discrete points called pixels (pixel - picture element).

The display communicates with its adapter, which may also be called a video card, video adapter, or controller. The display and the adapter are very closely related to each other and jointly determine the image quality - resolution, the number of reproduced colors, the regeneration rate (the number of frames per unit of time).

The resolution depends on the size of the screen and the minimum image element (the so-called "grain", equal to 0.24 ... 0.28 mm for the best monitors). For 14-inch monitors, the resolution is usually no more than 800 × 600 elementary dots (pixels), for 15-inch monitors - 1024 × 768, for 21-inch - 1280 × 1024 pixels.

The adapter's ability to display an image with a given resolution and color depth (i.e., the number of color shades) on the monitor screen is determined by the amount of RAM installed on the adapter board. To display 16.7 million shades of colors (24 bits per pixel), you need to install at least 1.37 MB of memory in the adapter at a resolution of 800 × 600 elementary dots, 3.75 MB at a resolution of 1280 × 1024 and 5.49 MB at a resolution of 1600 ×1200.

For a comfortable perception of the image, without tiring flickering, you need enough high frequencies vertical scan (recommended at least 85 Hz).

The principle of operation of a color monitor is similar to the principle of operation of a monochrome monitor, but the design of a color monitor is much more complicated. The color display contains three electron guns with separate control circuits. The screen is made in the form of a mosaic structure (rectangular matrix) consisting of phosphor grains of three glow colors: red (Red), green (Green) and blue (Blue). The grains are arranged in triplets (triads) so that the electrons of each of the three guns hit only the grains of "their" color. To ensure this, masks are installed in the path of electron movement.

The principle of operation of the color display is based on the physiological characteristics of human vision. So, with the same intensity of the glow of three multi-colored small neighboring grains, this section of the screen is perceived as a white dot. The glow of neighboring red and green grains is perceived as a yellow dot, and the glow of blue and green grains gives a blue dot, etc. By changing the intensity of the glow of the three primary colors (RGB), you can get any color or shade. This method of obtaining any colors is one of the color rendering systems and is called the RGB system (after the first letters of the corresponding English words).

Liquid crystal monitors (LCD) have the following advantages: low power consumption (2-3 times less than that of a CRT), the absence of X-ray radiation, static electrification, and geometric distortions. LCDM has low weight and dimensions: the thickness of the monitor does not exceed 5…6 cm. The disadvantages of LCDM are a limited viewing angle, lower contrast and color depth than CRT, significant brightness unevenness in different parts of the screen. LCM has a large percentage of defects in their production (the presence of "dead" pixels). This is now considered the main reason for the higher cost of LCDs compared to CRT monitors.

In cathode ray tubes, the phosphor is placed at certain points on the screen, forming a matrix. The flow of electrons is directed to these points with the help of continuous (analogue) control signals supplied to the deflecting system. The electron beam sequentially line by line “runs around” all points (pixels) of the screen and alternately changes the intensity of their glow.

A complete image on a CRT screen, obtained with the participation of all pixels, is called a frame. To get the illusion of a moving image, successive frames must quickly replace each other (at least 25...30 times per 1 s). In a CRT, during the movement of the electron beam from the beginning of the frame to its end, the glow of the first excited elements of the matrix (phosphor) has time to weaken somewhat. To reduce screen flicker, you have to increase the frequency of changing (updating) the next frames (they say: increase the frame rate). The vertical scanning frequency of the CRT must be at least 85 Hz.

The principle of operation of a liquid crystal monitor is significantly different from the principle of operation of a CRT monitor. The LCCM uses the physical effect of changing the spatial position of crystal molecules under the action of an electric field. Just like in a CRT, an LCD image is formed from a large number of dots (pixels), which form a rectangular matrix. However, in a liquid crystal matrix, the image formation process is controlled digitally. In the LCD, the glow of all elements of the entire row of the matrix (screen) changes simultaneously. LCD flicker is fundamentally less than CRT displays, since only changing pixels are updated during image formation. The display of static pictures does not require updating, so in these cases there is no flickering of the LCD screen at all. The LCD matrix (Liquid Crystal Display, LCD) is made of a substance that is in a liquid state of aggregation, but has the properties of crystals. Under the action of an electric field, liquid crystals change their spatial orientation (turn) and this varies the intensity of the transmitted light.

Rice. 10.11. Layered monitor design

The monitor is a multilayer structure (Fig. 10.11), which contains polarizers, a matrix of control transistors, color filters, glass plates, between which liquid crystals are placed.

The principle of operation of the LCDM (Fig. 10.12) is based on the effect of polarization. First, the light passes through the first polarizing filter (Polarizer 1), which is characterized by a certain polarization angle. Another polarizer (Polarizer 2) is installed in the LCD. Depending on the polarization angle of the second filter, the light will either be completely absorbed by it (if the polarization angle of the second filter is perpendicular to the polarization angle of the first filter), or pass unhindered (if the angles are the same). A smooth change in the angle of polarization of the transmitted light allows you to adjust the intensity of the visible (transmitted) light. The polarization angle of transmitted light is changed using liquid crystals. Their orientation in space depends on the magnitude of the control voltage applied to the transistor matrix.

Rice. 10.12. The principle of operation of the LCD

Thus, by changing the control voltage on each transistor of the matrix, it is possible to vary the spatial position of liquid crystals at a given point. A change in the spatial position of the crystals leads to a change in the angle of light polarization at a given point on the screen (and, hence, to a change in the intensity of the glow of a given point on the screen).

The discrete design of the LCD makes it possible, in principle, to dispense with analog-to-digital conversion, i.e., to work directly with digital signals. It is obvious that such a design is more promising compared to devices that work with analog signals. Recall that a CRT is an analog device. The signals on the deflection plates and the modulator are continuous. To control the operation of the CRT, it is necessary to transform the digital signal generated by the computer into an analog signal. However, any digital-to-analog conversion is associated with the occurrence of distortion and interference, complicating the design of controllers.

Monitor

The monitor is a device for visual display of all kinds of information, which is connected to the PC video card.

There are monochrome and color monitors, alphanumeric and graphic monitors, cathode ray tube monitors and liquid crystal monitors.

Cathode Ray Monitors ($CRT$)

The image is created using a beam of electrons, which are released by an electron gun. A high electrical voltage accelerates the electron beam, which falls on the inner surface of the screen, coated with a phosphor (a substance that glows under the influence of the electron beam). The beam control system drives it line by line across the entire screen (creates a raster) and regulates its intensity (the brightness of the glow of the phosphor dot).

$CRT$-monitor emits electromagnetic and x-ray waves, high static electrical potential, which have an adverse effect on human health.

Figure 1. Cathode Beam Monitor

Liquid crystal monitors ($LCD$) based on liquid crystals

Liquid crystal monitors (LCDs) are made from a liquid substance that has some of the properties of crystalline bodies. When exposed to an electrical voltage, liquid crystal molecules can change their orientation and change the properties of the light beam that passes through them.

The advantage of liquid-crystal monitors over $CRT$-monitors is the absence of electromagnetic radiation harmful to humans and compactness.

The digital image is stored in the video memory, which is located on the video card. The image is displayed on the monitor screen after reading the contents of the video memory and displaying it on the screen.

The stability of the image on the monitor screen depends on the frequency of image reading. The image refresh rate of modern monitors is $75$ or more per second, which makes the image flicker imperceptible.

Figure 2. LCD Monitor

Printer

Definition 2

Printer- a peripheral device designed to output numerical, textual and graphic information on paper. According to the principle of operation, a laser, inkjet and dot matrix printer are distinguished.

Provides near-silent printing, which is formed by the effects of xerography. The entire page is printed at once, which ensures high printing speed (up to $30$ pages per minute). The high print quality of laser printers is ensured by the high resolution of the printer.

Figure 3. Laser printer

Provides almost silent printing at a sufficiently high speed (up to several pages per minute). In inkjet printers, an ink head prints, ejecting ink under pressure from tiny holes onto the paper. The print head, moving along the paper, leaves a line of characters or an image strip. The print quality of an inkjet printer depends on the resolution, which can reach photographic quality.

Figure 4. Inkjet printer

It is an impact printer that forms characters with the help of several needles located in the printer head. The paper is pulled in by a rotating shaft, and an ink ribbon passes between the paper and the printer head.

On the printhead of a dot-matrix printer is a vertical column of small rods (usually $9$ or $24$) that are "pushed" out of the head by the magnetic field and hit the paper (through the ink ribbon). The print head, moving, leaves a line of characters on paper.

The print speed of dot matrix printers is slow, they produce a lot of noise and the print quality is not high.

Figure 5. Dot matrix printer

Plotter (plotter)

Definition 3

A device designed for complex and widescreen graphic objects(posters, drawings, electrical and electronic circuits, etc.) under PC control.

The image is applied with a pen. It is used to obtain complex design drawings, architectural plans, geographic and meteorological maps, business schemes.

Figure 6. Plotter

Projector

Definition 4

Multimedia projector(multimedia projector) - a stand-alone device that provides transmission (projection) on a large screen of information from external source, which can be a computer (laptop), VCR, DVD player, camcorder, document camera, TV tuner, etc.

$LCD$ projectors. The image is formed using a translucent liquid crystal matrix, of which $3LCD$ models have three (one for each of the three primary colors). $LCD$-technology is relatively inexpensive, therefore it is often used in models of various classes and purposes.

Figure 7 LCD Projector

$DLP$ projectors. The image is formed by a reflective matrix and a color wheel, which allows one matrix to be used to sequentially display all three primary colors.

Figure 8. DLP projector

$CRT$-projectors. The image is formed using three cathode ray tubes of basic colors. Now practically not used.

Figure 9. CRT projector

$LED$-projectors. The image is formed using an LED light emitter. Benefits include a long lifespan that is many times longer than that of projectors with a lamp, the ability to create ultra-portable models that can even fit in your pocket.

Figure 10. LED projector

$LDT$-projectors. The models use several laser light generators. The technology allows you to create compact projectors with very high brightness.

Audio output devices

Built-in speaker

Definition 5

Built-in speaker- the simplest device designed to play sound on a PC. The built-in speaker was the main audio playback device until inexpensive sound cards came along.

In modern PCs, the speaker is used to signal errors, in particular during the POST program. Some programs (for example, Skype) always duplicate the ringing signal to the speaker, but do not output the sound of the conversation through it.

64-bit Windows does not support the built-in speaker, which is due to a conflict between the means of rehabilitation and power management of the sound card.

Devices for outputting sound information that are connected to the output of a sound card.

Figure 11. Speakers and headphones

Peripherals conclusions are intended foroutput of information in the format necessary for the operator. Among them there are mandatory (included in the basic PC configuration) and optional devices.

Monitors

The monitor is a necessary information output device. The monitor (or display) allows you to display alphanumeric or graphical information in a form that is easy to read and control by the user. In accordance with this, there are two modes of operation: text and graphic. In text mode, the screen is presented in rows and columns. In graphical format, screen parameters are specified by the number of dots horizontally and the number of dotted lines vertically. The number of horizontal and vertical lines on the screen is called the resolution. The higher it is, the more information can be displayed per unit area of ​​the screen.

• · Digital monitors. The simplest - a monochrome monitor allows you to display only a black and white image. Digital RGB monitors ( Red-Green-Blue) support both monochrome and color mode (with 16 color shades).
• · Analog monitors. Analog signal transmission takes place in the form of various voltage levels. This allows you to create a palette with shades of varying degrees of depth.
• · Multi-frequency monitors. The video card generates clock signals that refer to the horizontal line rate and the vertical frame rate. The monitor must recognize these values ​​and enter the appropriate mode.

If possible, settings can be distinguished: single-frequency monitors that perceive signals of only one fixed frequency; multi-frequency, which perceive several fixed frequencies; multi-frequency, tuning to arbitrary values ​​of the frequencies of synchronous signals in a certain range.

· Liquid crystal displays (LCD). Their appearance is associated with the struggle to reduce the size and weight of portable computers.

The main disadvantage is the inability to quickly change pictures or quickly move the mouse cursor, etc. Such screens need additional illumination or external lighting. The advantages of these screens are in a significant reduction in the spectrum of harmful effects.

· Gas plasma monitors. They do not have the limitations of LCD screens. Their disadvantage is the high consumption of electricity.

It is necessary to single out the group touch screens , since they allow not only to display data on the screen, but also to enter them, that is, they fall into the class of input / output devices.

This relatively new technology is not yet widely used.

Such screens provide the easiest and shortest way to communicate with a computer: just point to what interests you. The input device is fully integrated into the monitor.

Used in information and reference systems.

PC users spend many hours in close proximity to working monitors. In this regard, display manufacturers have increased their attention to equipment.

Their special means of protection against all types of influences that adversely affect the health of the user. Low radiation monitors (LR monitors, from low Radiation).

Other methods are used to increase the comfort of working with displays.

Printers

A printer is a widespread device for outputting information to paper, its name is derived from the English verb to print - to print. The printer is not included in the basic PC configuration. Exist different types printers:

• · generic printer works like an electric typewriter. Advantages: a clear image of characters, the ability to change fonts when replacing a typical disk. Disadvantages: noise during printing, low print speed (30-40 characters per second), printing of a graphic image is impossible.
• · Dot matrix (dot) printers- these are the cheapest devices that provide satisfactory print quality for a wide range of routine operations (mainly for preparing text documents). They are used in savings banks, in industrial conditions where roll printing, printing on books and thick cards and other media made of dense material is required. Advantages: acceptable print quality, subject to a good ink ribbon, the possibility of carbon copy printing. Disadvantages: rather low print speed, especially for graphic images, significant noise level. Among matrix printers, there are also fairly fast devices (the so-called Shattle printers).

Inkjet printers provide better print quality. They are especially useful for color graphics output. The use of inks of different colors gives a relatively inexpensive image of acceptable quality. The color model is called CMYB (Cyan-Magenta-Yellow-Black) after the names of the primary colors that form the palette.

Inkjet printers are much less noisy. The print speed depends on the quality. Quite effective in creating brochures, calendars, greeting cards. This type of printer occupies an intermediate accumulation between dot matrix and laser printers

· Laser printers - have even higher print quality, close to photographic. They are much more expensive, but the print speed is 4-5 times faster than dot matrix and inkjet printers. The disadvantage of laser printers is rather stringent requirements for paper quality - it must be thick enough and not loose, printing on plastic-coated paper, etc. is unacceptable.

Laser printers are especially effective in the production of original layouts for books and brochures, business letters and materials that require high quality. They allow you to print graphics, drawings at high speed.

Laser printers are divided into two types: local and network. You can connect to network printers using an IP address. Increasingly, color printers can be found on the market among laser printers. Color laser printers are also found among office (network) printers.

· LED printers - alternative to laser. The developer is OKI.

Thermal printers. Used to produce photographic quality color images. Requires special paper. Such printers are suitable for business graphics.

Printer on Micro Dry technology. These printers give full photo natural colors, have the highest resolution. This is a new competitive direction. Much cheaper than laser and inkjet printers. The developer is Citizen. Prints on any paper and cardboard. The printer operates at a low noise level.

Plotters

This device is used only in certain areas: drawings, diagrams, graphs, diagrams, etc. Plotters have found wide application in conjunction with programs of automatic design systems, where design or technological documentation becomes part of the results of the program. Plotters are indispensable in the development of architectural projects.

The drawing field of the plotter corresponds to A0-A4 formats, although there are devices that work with a roll that do not limit the length of the output drawing (it can be several meters long). That is, there are tablet and drum plotters.

• · Tablet plotters, mainly for A2-A3 formats, fix the sheet and draw a drawing using a writing unit moving in two coordinates. They provide a higher accuracy of printing patterns and graphs compared to drum printing.
• · Roll (drum) plotter - remains in fact the only developing type of plotter with a roller feed sheet and a writing unit that moves along one coordinate (paper moves along the other coordinate).

common cutting plotters to display the drawing on film, instead of a writing unit, they have a cutter.

Plotters usually communicate with a computer through a serial (COM), parallel (LPT) or SCSI interface. Some models of plotters are equipped with a built-in buffer (1 MB or more).

Hewlett-Packard devices are currently the de facto standard for tablet plotters. In addition, HP-GL (Hewlett-Packard Graphics Language) has also become a de facto industry standard. Roland's DXY models are considered good plotters. In addition to being HP and HP-GL compatible, these models also use their own DXY-GL graphics language.

Projection technology

Multimedia projectors have firmly entered our lives at the end of the 20th century, and now it is impossible to imagine many areas of human activity without them. These are the educational process, presentations, show business and home cinema. A multimedia projector allows you to play on a large screen information received from a wide variety of signal sources: a computer, a VCR, a camcorder, a camera, a DVD player, a game console. The modern projector is the most perfect link in the chain of evolution of projection equipment, which began with slide projectors, which make it possible to demonstrate photographic transparencies on a large screen. They were replaced by the so-called overhead projectors, projecting images from translucent materials of large sizes. The possibilities of modern multimedia projectors are truly limitless compared to their predecessors.

The image in a multimedia projector is formed in several main ways: using liquid crystal panels (LCD technology) and using DMD micromirror chips (DLP technology). In LCD projectors, the light from the lamp passes through a liquid crystal panel, on which, like on ordinary film, but with the help of a digital electronic circuit, an image is created. The light passes through the panel and the lens, and as a result, an image magnified many times over is projected onto the screen. In DLP projectors, the light from the lamp is reflected from many electronically controlled micromirrors and also enters the screen through the lens. The main characteristic of a multimedia projector is its brightness, or luminous flux. The more powerful the luminous flux, the larger the image size can be obtained with a given illumination and the quality of the screen material. Lumen output (measured in ANSI Lumens) will vary depending on projector design, LCD panel quality, lamp wattage and lamp type.

Multimedia projector is a modern and high-tech device. The reliability of most of the models produced is great, and the user is unlikely to have to contact a service center with a request for repairs. The only replaceable part of the projector is its lamp. Most projectors use high-brightness arc lamps with a smoother spectrum than incandescent lamps. Their average service life is 2000 hours of operation. Sometimes it is useful to use the lamp saver function, which doubles the lamp life. keyboard scan printer monitor

Audio system

In personal computers, a wide variety of schemes for generating sound signals are used - from simple to complex.

It seems that the problem with sound for personal computers is finally solved. Rarely seen motherboards not equipped with an audio controller. Nevertheless, even if we consider the issue with audio cards closed, the topic of acoustic systems remains burning.

This question remains burning, because many users are not limited to watching videos and playing games with surround sound. True audiophiles prefer high-quality stereo sound with surround sound and deep bass, not to mention enthusiasts who create music using their personal computers. For them, in general, a mandatory element of a home studio is high-quality stereo acoustics, even if the rest of the role is assigned to a computer with a sound card.

These days there are a lot of acoustic systems on the market, consisting of two active speakers, and made according to the 2.1 system.

More recently, the ideal in the world of computer (and not only) speaker systems was a 5.1 system (five satellites and one subwoofer), but recently acoustic manufacturers have been expanding the capabilities of their systems, which first led to the appearance of a 6.1 system, and later 8.1.

Information output devices - These are devices that translate information from machine language into forms accessible to human perception. Output devices include: monitor, video card, printer, plotter, projector, speakers. Input devices are those devices through which information can be entered into a computer. Their main purpose is to implement the impact on the machine.

Monitor (display) - a universal device for visual display of all types of information.There are alphanumeric and graphic monitors, as well as monochrome monitors and color image monitors - active-matrix and passive-matrix LCDs. Rresolution is expressed by the number of image elements horizontally and vertically. Points - pixels (picture element) are considered elements of a graphic image. Text elements

Exist:

1) cathode ray tube (CRT) monitors.

2) liquid crystal monitors (LCD) based on liquid crystals. liquid crystals- a special state of some organic substances, in which they have fluidity and the ability to form spatial structures similar to crystalline ones. Liquid crystals can change their structure and light-optical properties under the influence of electrical voltage.