Data output devices. Additional devices What are computer output devices
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 virtually silent printing, which is formed by the effects of xerography. The whole 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 printhead 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 wide-format 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) to a large screen of information from an 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
Or Graphics tablet, - a device for digitizing graphic images, which allows you to convert an image obtained as a result of the movement of the operator's hand into a vector format.
Digitizers are used in computer-aided design (CAD) systems to enter graphic information into a computer in the form of drawings and drawings: the designer moves the pen-cursor over the tablet, and the image is recorded as a graphic file.
The digitizer consists of two elements: base (tablet) and pointing device (pen or cursor) moved on the surface of the base. When you press the cursor button, its position on the surface of the tablet is fixed and the coordinates are transferred to the computer.
Digitizers are divided into electrostatic and electromagnetic, depending on the mechanism for determining the location of the pointing device.
Graphic tablets of digitizers are made on firmaments (tablet digitizers) and flexible bases (flexible digitizers). Flex-based digitizers are lighter, more compact, easier to transport, and cheaper.
Pointing devices in digitizers, they are performed in the form of a cursor or a pen.
The pen is a pointer equipped with one, two or three buttons. There are pens that determine the force with which the pen tip is pressed against the tablet, and have 256 degrees of pressure. The thickness of the line, the color in the palette and its shade depend on the degree of pressure. To realize artistic possibilities, you need software such as Adobe Photoshop , CorelDRAW and etc.
Cursors are used primarily by CAD designers. They are performed by 4-, 8-12-, 16-keys. Usually two to four keys are used, the rest are programmed in application programs, for example, in Autocad. One of the best is the 4-button cursor from CalComp.
Lesson topic. Information output devices.
About 10 years ago it was only a dream to work on your computer like a typewriter or organize a mini-printing house with it, watch TV programs, listen to CDs.
But time flies quickly, and today everyone knows those peripheral hardware that help bring the possibilities of personal computers closer to almost limitless.
Of course, we are talking about all kinds of information output devices, the main purpose of which is to convert the information contained in binary digital form in the machine's memory into a form understandable for human perception.
Output devices are computer hardware designed to output digital information from it by converting it into an analog form and presenting it in a form understandable to a person.
The hardware of any output device, as well as the input device, includes the device itself, the control unit - the controller (or adapter), interface cords with connectors corresponding to the ports on the motherboard, and the driver of this particular device.
We know that thanks to their senses, a person can perceive visual, symbolic, audio information, tactile (tactile) information, smells and tastes.
From these forms today's personal computer, perhaps, cannot satisfy only our sense of smell and taste buds - the output of "smelling" and "tasty" information is the prospect of the future. But the computer gives out all the other forms understandable to us in a completely real form.
According to this, we can divide all information output devices into several classes:
Monitors - output of video information;
Printers - output of sign-written information;
- plotters(plotters) - output of graphic information;
Speakers, headphones, speakers - output of sound information;
Virtual reality devices - output of tactile information.
Lesson topic. Monitors: classification, characteristics and principle of operation.
1. Monitors: classification, characteristics and principle of operation.
Monitor— this is a device for displaying symbolic and graphic information on the screen, by converting its computer (machine) representation into a form understandable to humans.
It can be said that a monitor is a device for displaying visual (visual) information.
Otherwise, monitors are called displays, less often - video terminals (usually this is the name of a monitor remote from other parts of the computer). The monitor is one of the main parts of a PC, and the convenience of using a computer largely depends on its characteristics.
The monitor is connected to the motherboard through a video adapter board (video card), and its normal operation is ensured by a set of drivers - a special program that comes with the monitor.
The combination of a monitor, video card and their drivers forms the video system of a personal computer.
Today you can meet a huge number of monitors of various brands and models. In order to somehow understand their diversity, you need to clearly understand the signs by which they are classified.
We will consider their classification according to:
1) the size, which is determined, as with TVs, along the diagonal of the screen;
2) functional features - alphanumeric or graphic;
3) the number of reproducible colors - monochrome or color;
4) the physical principles of image formation - based on a cathode ray tube (CRT), liquid crystal, plasma and electroluminescent.
A reasonable choice in terms of "screen size" among monitors can be a display with a diagonal of 17 inches or more.
Alphanumeric monitor(today, by the way, you will not find it anywhere) can only reproduce a limited set of characters. It can be compared to the display of conventional electronic wristwatches, where only numbers and letters can be seen. You can’t reproduce complex pictures on it.
Graphic monitors adapted to reproduce any information: both digital and graphic.
Monochrome monitor can reproduce the image in any one color with different gradations of brightness. A color monitor displays an image in several colors at once. Their number can be from 16 to 16,800,000.
Plasma displays are a set of gas-discharge cells - they are expensive, and their energy consumption is quite high.
Fluorescent displays consist of a matrix of active indicators that give a high-quality image, but they are also very energy-intensive and expensive.
Base monitors cathode ray tube (CRT) They work according to the same “principle as conventional televisions: the electron beam emitted by the electron gun is modeled by special electrodes and hits a screen covered with a phosphor. An image on a screen is made up of many individual dots called pixels.
Pixel— the minimum size of the image on the screen.
Under the action of the sweep, the electron beam slides across the screen line by line and forms an image.
Colors on the monitor(as on a television screen) are obtained by an additive (total) mixture of three primary colors: RGB, i.e. red (Red), green (Green) and blue (Blu). This triad, mixed with the same intensity, gives a white color, and in order to achieve color shades, the intensity of each of these colors is dosed in the required proportion.
The electromagnetic radiation of CRT monitors is generated by a gun that accelerates electrons and is located at the back of the monitor, and X-ray radiation occurs at the moment of collision of electrons with the inner surface of the screen. Of course, modern CRT monitors have anti-radiation protection, but it is not possible to completely suppress the resulting radiation.
LCD monitor does not have these shortcomings: its electromagnetic fields are at the level of the background from the power supply, and the image it creates does not flicker at all. This circumstance alone makes those who are professionally connected with computer technology seriously think about purchasing an LCD panel. The disadvantages of the LCD monitor include not-yet-sufficiently accurate color reproduction, as well as uneven image brightness. In favor of purchasing an LCD monitor is its ergonomics. This applies to those who spend a lot of time in front of the TV screen. The fact is that some models of LCD monitors, in addition to the standard VGA input for connecting to a computer, also have a video input, to which you can send a signal from a TV, TV tuner or VCR. This makes it possible to get rid of the harmful effects of a television CRT, which is much stronger than that of a CRT monitor.
Modern thin-film semiconductor liquid crystal monitors use TFT technology. The liquid crystal substance is located between two layers of glass.
The high efficiency of LCD monitors is due to the low consumption of materials and energy.
Traditional CRT monitors update the image on the screen by one pixel, so the frame rate is extremely important for them, which determines the refresh time of the image. The visual flickering of the image on the screen depends on its value. In LCD monitors, the image is updated progressively, so it does not judder at almost any reasonable frame rate.
With the same size and high image contrast, LCD panels have an undeniable advantage over traditional CRT monitors: they are much lighter and take up very little space, and some models can be hung on the wall, which completely saves you from having to allocate space under the monitor at the workplace. table.
Attention should be paid Another convenient feature that some models of LCD monitors have is the ability to rotate the display by 90 ° and thus change the landscape orientation of the screen to portrait. This is very useful when working with Web pages or large documents, where the extra height of an image in portrait orientation is very useful.
The main features of monitors are permissiveability, the sizescreen coverage points and frame rate.
Resolution is the maximum number of dots (pixels) that this type of monitor can display horizontally and vertically.
It is clear that the more these points fit horizontally and vertically, the better the picture on the monitor will be.
The resolution depends both on the characteristics of the monitor itself and, even to a greater extent, on the characteristics of the video controller, which provides for two monitor operation modes: text and graphic.
The clarity of the image on the monitor screen depends on the resolution value, and it is generally accepted that in text mode monitors do not differ much from each other in image clarity, and in graphics mode, image quality increases with increasing resolution.
The image quality is significantly affected by such a physical parameter of the display as screen dot size, or, as computer scientists say, "phosphor grains." This parameter defines the distance between points.
For modern monitors currently on sale, this parameter varies from 0.32 mm to 0.25 mm. Do not confuse the concepts of "grain" and "pixel". The grain size cannot be changed, and the pixel size depends on the video adapter mode. A good monitor should be considered a display with a dot size of no more than 0.28 mm.
For another important feature monitors applies max. to base frequency. Good stability of the image and the absence of flicker on the screen depend on it. The higher the frame rate, the less "ripple" your monitor screen will have.
It is recommended to use monitors with a refresh rate of at least 85 Hz, which means that the image on the screen is updated 85 times per second. A lower frequency is dangerous for the eyes - flickering is tiring and can lead to premature loss of vision.
note that all the most important characteristics of the monitor are directly related. Changing one of the parameters will lead to a change in the operation of the other, for example, by reducing the resolution, the number of supported colors will increase (as, indeed, the maximum scanning frequency).
Almost all modern monitors are equipped with a special digital control that allows you to manually adjust a variety of parameters:
· proportional compression/stretching of the image horizontally and vertically;
image shift horizontally or vertically;
Correction of "barrel-shaped distortions" (that is, those when the edges of the image on the screen are too convex or, conversely, concave);
trapezoidal and parallelogram distortions, also associated with the "geometry" of the image;
color "temperature", i.e. the ratio of the main screen colors - red, green and blue.
On professional monitors high-end, you can find dozens of other various settings and adjustments, many of which are carried out directly from the computer.
The back side of such monitors is decorated with many unusual connectors through which fine-tuning of colors and image parameters is carried out. In particular, the so-called "calibration" - the exact adjustment of colors on the monitor to the specified standards.
Lesson topic. Video adapters.
Video card (video adapter). The main purpose of a video card is to control the process of displaying information on the monitor screen, its characteristics must correspond to the monitor parameters. The higher the resolution of the monitor screen and its size, the higher the requirements for the video card. Structurally, a video card is usually made in the form of an expansion board, which is inserted into the corresponding slot on the motherboard. In older computers, ISA buses were used for this, then PCI. In modern computers, the video card uses a special slot - AGP.
The main components of a modern video adapter are a video controller, video BIOS, video memory, a special RAMDAC digital-to-analog converter, and interface chips with a system bus.
All modern video subsystems can work in two main video modes: text or graphics. Text mode in modern operating systems is used only at the boot stage.
In graphics mode 1 ... 32 bits are allocated for each image point (pixel) (from monochrome to color). The maximum resolution and the number of reproducible colors of a particular video subsystem primarily depend on the total amount of video memory and the number of bits per image element. There are several video card standards. The main parameters in these standards are resolution (the number of pixels horizontally and vertically), the number of colors displayed on the screen and the frame rate, which determines the frequency of redrawing (regeneration) of the image on the monitor screen.
Currently, all video cards must comply with the VESA SVGA standards, which defines the following main characteristics:
resolution - the number of horizontal pixels x the number of vertical pixels:
640x480; 800x600; 1024x768; 1152x864; 1280x1024; 1600x1280; 1800x1350;
color depth - the number of bits per pixel (colors).
Frame rates(56; 60; 72; 75; 85; 90; 120 Hz). Frame rate is an extremely important parameter in terms of ergonomics. The image on the monitor screen is drawn by an electron beam with a frame rate equal to the frame rate. If this frequency is below 75 Hz, then the eye has time to notice the flickering of the image, which is tiring for it. The flicker is most noticeable on a white background.
In order to set the desired color depth, open the Control Panel and select "Display" (or right-click on the desktop and select "Properties"). Go to the "Settings" tab. In the "Color Palette" section, select the desired mode and click the "Apply" button.
Set to HighColor or TrueColor for normal operation.
Video memory size. This parameter determines the ability of the card to support various options for displaying images on the monitor screen.
Video memory size, required to support a particular mode, is determined as follows: you need to multiply the number of pixels in the image horizontally and vertically by the number of bits and divide the resulting value by 8 (the number of bits in a byte). This way you can get the maximum possible resolution for different amounts of video memory. It is easy to determine that to support the maximum resolution of 1600x1280 at a color depth of 32 bits, 8 MB of video memory is required. Working with graphic applications, three-dimensional graphics and video imposes increased requirements on all the characteristics of a video card, especially on its memory. Therefore, cards with a memory capacity of at least 128 MB are currently being produced.
Security standards. There are several standards that leading monitor manufacturers adhere to. We list only the most famous.
Standard DPMS defines the power management modes that can be used when the monitor is idle.
In mode Standby only blanking of the screen occurs (switching off the high voltage on the kinescope), in the mode Suspend- decrease in the temperature of the filament of the CRT cathodes.
Modern motherboards support one more mode - Hibernate("hibernation"). When you enter this mode, the entire contents of RAM are stored on the hard disk, the monitor and hard disks are turned off, after which the computer turns off. The advantage of this mode is that when the computer is activated, which is usually carried out by pressing any key on the keyboard, the state of the desktop, open and minimized windows is restored, i.e. the computer completely reproduces its state at the time of "falling asleep".
Swedish Nutek Specification- The National Council for Industrial and Technical Development of Sweden requires that the monitor switch to the first energy conservation mode (Standby) if the mouse or keyboard has not been used for more than 5 minutes (but less than 1 hour); at the same time, the monitor can return to its normal state in 3 s. In this mode, the power value must necessarily be less than 30 W, and preferably less than 15 W. After 70 minutes, the power consumed by the monitor must be reduced to a level of less than 8 W, and preferably to a level of less than 5 W. The exit time from the second mode (Off) is not defined. Nutek's energy efficiency levels have been included in the TCO"92 and TCO"95 rating systems.
The abbreviation TSO stands for as the Swedish Federation of Trade Unions. Initially, environmental standards applied only to monitors as the most dangerous element of a computer. The developers were only interested in minimizing the level of various radiations. TCO"92 turned out to be very rigid in this sense. Its successor TCO"95 only expanded the scope of TCO, for the first time making an attempt to describe the requirements for other computer elements. In addition, special attention has been paid to the protection of the environment during the production process and to the safe disposal of all certified products after their useful life. The requirements of the TCO "99 standard are mainly focused on ergonomics, ecology and environmental protection. From now on, LCD monitors, computers, laptops and keyboards fall under the standard as a separate line.
All requirements of the TCO "99 standard are combined into seven groups:
1. visual ergonomic requirements (image clarity requirements);
2. visual ergonomic requirements (image stability requirements);
3. factors of external influence;
4. requirements for emissions and energy saving;
5. electrical safety requirements;
6. environmental requirements;
7. additional features.
Lesson topic. Additional video signal processing devices.
To better understand what will be discussed, imagine a stereo movie. Remember, in the recent past, we had stereo cinemas in our country, where before watching a movie, each viewer was given stereo glasses. And if a tree fell on the screen, then, looking at it through the stereo glass, the whole hall deviated, since there was an illusion that the tree fell exactly on you. It was the effect of "virtual reality".
Virtual reality is the process of modeling physical effects using video technology.
Image- this is what the user of a personal computer is dealing with. This means that in order to achieve the “stereo” effect on the monitor screen, it is necessary to make a “three-dimensional” image from a two-dimensional “picture”. To do this, you just need to divide the picture perceived by our eyes on the monitor into two pictures, but specifically for the right and left eyes, and these pictures will differ from one another only by the angle of rotation relative to the user.
These pictures are required show simultaneously, on the same screen, where they will overlap one another. And in order for the viewer to perceive them as a whole and look at the same time “in two eyes”, you need to put on him special multi-colored glasses, in which each eye perceives only the picture that is intended for him.
This technology is theoretically quite simple. The equipment for it, in addition to penny glasses, is not required. But whoever wants to create programs, games and films for such glasses should know that this is a very time-consuming and complex process. Therefore, all over the world there are only a couple of dozen games and encyclopedias created for multi-colored "virtual" glasses.
Later, another method appeared artificial separation of the picture using the hardware of the PC itself. A small amount of "phase shift" is needed to create a copy of the picture on the screen. This copy, slightly rotated in relation to the original, is fed along with the original to the screen at the right moment, and the “three-dimensional” picture is ready, mind you, practically without the participation of a complex program. In this way, any toy can be “trimmed”, even if it knew absolutely nothing about “virtual reality”!
Then cheap plastic glasses were replaced by two small LCD monitors - one for the right, the other for the left eye, and they were moved closer to the eyes, at a distance of several centimeters, which, mind you, is very tiring for the eyes and causes a headache.
It is on this principle thundered 5 years ago was created "virtual reality helmet", which is still sold in a number of computer companies at a price of 500 to 700 dollars. There is another, perhaps optimal, both in terms of price and quality technology of "virtual reality" - liquid crystal glasses. By themselves, these glasses do not show anything. Or they can only alternately cover either one or the other eye with special liquid-crystal “shutters”. This process occurs at a high speed - and in parallel to it, pictures for the left and right eyes are fed to the monitor screen. In this case, a special device is engaged in the “breakdown” of a regular image, which is installed between the video card and the monitor.
The only drawback of this method- the frequency of the vertical scan of the image you see is halved due to the alternate display of the picture, which means that only the best monitors will “pull” the frequency of 120 Hz in 800 x 600 mode. The last “squeak” of spectacle fashion is the so-called "virtual monitors". Behind this high-profile name are the “glasses” already familiar to us with liquid crystal displays, in the arms of which solid headphones are inserted that imitate high-quality sound.
Lesson topic. Printers: classification, characteristics and principle of operation.
1. Printers - devices for outputting text and graphic information from a personal computer to paper.
In modern printer models, it is possible to output information not only to paper, but also to another kind of media, for example, synthetic film.
Printers- a rather extensive class of devices, including up to 1000 different modifications. To somehow determine the characteristics, printers are classified by:
color (color and black and white);
· printing speed (this parameter is measured in the number of printed characters per unit of time). For modern printers, this parameter can reach several thousand characters per second;
By resolution (this parameter reflects the ability of the printer to display small lines and dots and is measured by the maximum number of lines, the length of which is equal to their width, per square centimeter or inch). For modern printers, this parameter can reach several
thousand dots per inch (dpi - inch per pixel);
By the width of the printer carriage (this parameter reflects the maximum possible document format);
By printing methods (shock and unstressed);
on the formation of output information when printing: sequential - the document is formed character by character, parallel (linear) - the entire line is formed at once, and page - the image of the whole page is formed;
· for printing images on paper: letter, matrix, thermal, inkjet, laser.
All printers, as a rule, work in two modes: text and graphic.
In text mode, codes of characters that need to be printed are sent to the printer from the computer. Printers support the most common fonts and their varieties.
When printing, it is possible to choose one of four quality modes for the resulting image:
Draft print mode (Draft);
Near-print mode (NLQ);
Printer-quality print quality (LQ) mode;
Super Quality Mode (SLQ).
Switching operating modes, depending on the type of printer, can be carried out both in software and in hardware, by pressing the buttons available on the printers.
In graphics mode, codes are sent to the printer that determine the sequence and location of image dots. Modern printers in graphics mode, due to the pseudo-graphics symbols they have in their memory, make it possible to implement service printing modes (dense, double-width, two-pass printing, multi-color printing, etc.).
Every day, sitting down at his workplace in the office, a person takes a mouse in one hand and begins to perform his duties. He knows why he needs a keyboard, a printer, a scanner, but he does not even imagine that they have their own official name. All this - and the output of information.
How it works
All devices in a personal computer are controlled by a central processing unit. To ensure interaction with it, the output and input devices make requests to the logic element of the motherboard. It serves to provide communication and processing requests from external devices to the north bridge or the central processor if there is no bridge.
In general, computer science deals with the study of the structure of a personal computer. It defines input and output devices as the components of a typical personal computer that provide the user with the computer. But before proceeding with the description of all devices, the basic I / O device deserves special mention. It's also BIOS. This chip on the motherboard of a personal computer provides an initial check of all connected devices and starts the operating system.
Classification
Personal computer input and output devices can be classified in different ways. The determining factor for this will be their functional responsibilities.
The first item is the main input-output devices. In fact, only one item could be specified here - the keyboard, since without it, not a single user computer will continue to boot. You can completely turn off the monitor and mouse, but the computer will not work without a keyboard. The exception is server computers that work without external devices connected at all. So, the main input / output devices, without which a normal user will not be able to work, are:
- keyboard;
- monitor;
- mouse.
You can also select additional I / O devices:
- printers;
- scanners;
- joystick;
- projector;
- I/O devices also include sound devices.
This is not a complete list of possible devices that interact with the user, it is possible to list them for a very long time. Therefore, let's look at the input / output devices of the computer in more detail.
Monitors
Computer monitors have undergone many changes throughout their history. Starting from the old ones using a cathode ray tube, and ending with modern LCDs.
The monitor or display itself is a device that serves to output to the end user. They can be divided according to several criteria.
1. By type of information.
- Alphanumeric. These displays are designed to display textual information only.
- Graphic. We encounter these monitors every day, sitting down at a personal computer. They are intended to present information in graphical form, including video.
2. By screen type.
- on the basis of such you may have worked in 2000.
- LCD is a liquid crystal "flat" display, which is now used everywhere. This type of monitor is also used in laptops.
- Plasma.
- Laser - has not yet entered mass production.
Keyboards
What can be said about keyboards? The fantasy of manufacturers in this area has stepped far ahead, and a sense of humor pushes for the most daring experiments.
Among the keyboards, you can find minimalistic options - without a side additional panel with numbers, and huge gaming keyboards with built-in joysticks, additional buttons and speakers. There are keyboards with an additional USB-connector and pink keyboards with "incomprehensible buttons" for "blondes". There are also silicone keyboards that roll up to make them easier to carry around, or simply fold up three times.
If you are going to buy a keyboard for yourself, just go to a computer store and choose the one that suits your taste.
mouse
Computer mice are such computer input / output devices, without which the work of an ordinary user is impossible. If an advanced user can navigate through folders and files, as well as some programs and games exclusively using the keyboard, then the average person is simply not able to do this. For all the time of existence, computer mice have undergone not so strong changes.
The first mice worked on the basis of a ball in the base. Moving it in different directions, the ball rotated and controlled the controllers.
Then he was replaced by optical mice based on LEDs. The first generation of optical mice required the obligatory presence of a special mat, on which shading was applied, which contributes to increased light reflectivity of the surface. Moreover, the first mice had personal mats, they could not be replaced with others.
The second generation of optical mice has a more complex device. A mini video camera is installed on the bottom of the mouse, which continuously takes microphotographs of the surface and compares them with each other to determine the displacement of the device.
Mice are newer devices. Among their advantages are low power consumption, reliability, lack of luminescence.
Another version of the mouse is found as an addition to the graphics tablet. Such induction mice are quite inconvenient to use, since they cannot be replaced with more comfortable ones that fit the hand, and the increased accuracy is discredited by the small ability to move away from the tablet with it.
Printers
These are printing devices. For all the time of its existence, printers have not changed much. Technologies are developing, laser printers are replacing inkjet printers, however, previous generations continue to live. What is the reason for this? The fact is that different types of printers are suitable for different types of printing. They all perform the same function and do not differ much in design. There are the following types of printers:
- matrix;
- jet;
- laser;
- thermal printers.
In the matter of choosing such a device, people usually adhere to personal preferences and habits. However, if you are going to print photos on it, and not only text documents, then laser is more suitable for you due to the increased print quality.
Scanners
An input device for a computer. The peculiarity lies in the fact that scanners enter information into the PC exclusively in graphical form. The development of scanners has stalled solely on changing their sizes. At first they became smaller and more compact, and then they were replaced by huge "combines" - output and input devices that combine a copier, printer and scanner.
Sound
Each of us likes to watch movies, listen to music at home. Speakers, headphones, audio systems and home theater systems, as well as headsets and microphones, all refer to audio output and input devices.
There are many different microphones and speakers, differing in the quality of audio recording or playback, respectively. Probably, anyone can determine for himself how good the sound of a speaker is. When choosing an audio system, it is also recommended to be guided by the design and power to your taste.
Video
To work with video graphics, special output and input devices are distinguished - cameras and projectors.
A projector is a device designed to create an image of an object on a large screen. There are the following types of projectors:
- Diascopic. The image appears due to the passage of light rays through a transparent film with a picture.
- Episcopal. Creates an image using the projection of reflected rays.
- Epidiascopic creates an image of both transparent and opaque objects on the screen.
- Multimedia the projector is directly related to the topic of the article. This is a device for outputting graphic information from a computer to a large surface.
As for the cameras, there is no need to tell anyone. In most cases, the higher the resolution of the shooting camera, the better the finished picture. With the advent of laptops, USB cameras began to be replaced by built-in laptop monitors.
After reading this article, you learned what output and input devices exist, what types they are divided into, and what types of them are relevant today. If you are going to independently equip your work and play space, as well as independently choose the devices that you want to have at hand at home, then this article should help you with choosing gadgets.
Remember the main rule of the buyer: more expensive does not mean better. In a computer store, when purchasing a printer or headset, you may well overpay for the brand, and then regret your purchase for a long time.
HP printers are an example. Yes, they are considered one of the best, but replacing an empty cartridge or just a small malfunction will cost you a pretty penny solely because of the manufacturer's fame.
When buying a sound system, feel free to check the sound and performance of the speakers. And if you are going to buy a webcam, then test its image, since the resolution declared in the documentation may not always correspond to the existing one.
And the main rule. When purchasing any product, check with the seller for warranty information. For example, for some devices, services require the box in which the unit was shipped. A good example is Asus laptops. In most cases, there is no information anywhere on the store's website that manufacturers require a branded box when contacting a service center.
Be careful and happy shopping!
You can connect additional devices to your computer.
Computer output devices
Computer input devices
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This is a microphone. From microphone computer introduces sound to your memory. The microphone is an input device. |
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This is a scanner. The scanner allows the computer enter texts and drawings from paper in your memory. The scanner is an input device. |
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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).
Introduction
The computer is a universal device for processing information. In order for a computer to process information, it must somehow be entered there. To carry out the input of information, special devices were created - this is primarily a keyboard, CD-ROM. Getting into the computer, the information is processed and then the possibility of outputting this information is realized, i.e. the user has the ability to visually perceive the data. To display information, the main devices are used - a monitor, a video adapter and a printer. After entering and processing information, it can be stored, for which the hard disk, magnetic disks and optical data storage facilities were created. In this control-course work, the topic “Input / output devices of information” is presented.
Information output devices 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. The variety of input devices produced has given rise to entire technologies from tactile to voice. Although they work on different principles, they are intended to implement one task - to allow a person to communicate with a computer. Graphic input devices are widely used due to the compactness and clarity of the way information is presented to a person. According to the degree of automation of the search and selection of image elements, graphic information input devices are divided into two large classes: automatic and semi-automatic. In semi-automatic input devices for graphic information, the functions of searching and selecting image elements are assigned to a person, and the coordinates of the read points are converted automatically. In semi-automatic devices, the process of searching and selecting image elements is carried out without human intervention. These devices are built either on the principle of scanning the entire image with its subsequent processing and transfer from a raster form to a vector representation, or on the principle of line tracking, which provides reading of graphic information presented in the form of graphs, diagrams, contour images. The main areas of application of graphic input devices are computer-aided design, image processing, training, process control, animation and many others. These devices include scanners, coding tablets (digitizers), light pen, touch screens, digital cameras, camcorders, computer keyboard, mouse, and others.
Input devices- devices for entering (inputting) data into a computer during its operation. 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. The variety of input devices produced has given rise to entire technologies from tactile to voice. Although they work on different principles, they are intended to implement one task - to allow a person to communicate with a computer. Graphic input devices are widely used due to the compactness and clarity of the way information is presented to a person. According to the degree of automation of the search and selection of image elements, graphic information input devices are divided into two large classes: automatic and semi-automatic. In semi-automatic input devices for graphic information, the functions of searching and selecting image elements are assigned to a person, and the coordinates of the read points are converted automatically. In semi-automatic devices, the process of searching and selecting image elements is carried out without human intervention. These devices are built either on the principle of scanning the entire image with its subsequent processing and transfer from a raster form to a vector representation, or on the principle of line tracking, which provides reading of graphic information presented in the form of graphs, diagrams, contour images. The main areas of application of graphic input devices are computer-aided design, image processing, training, process control, animation and many others. These devices include scanners, coding tablets (digitizers), light pen, touch screens, digital cameras, camcorders, computer keyboard, mouse, and others.
Chapter 1. Information output devices.
1.1 Monitor
The monitor provides information communication between the user and the computer. The first microcomputers were small blocks, in which there were practically no means of indication. All that the user had at his disposal was a set of flashing LEDs or the ability to print the results on a printer. Compared to modern standards, the first computer monitors were extremely primitive: text was displayed only in green, but in those years it was almost the most important technological breakthrough, since users were able to enter and output data in real time. With the advent of color monitors, the screen size increased, and they moved from portable computers to the desktop of users. There are two types of monitor: cathode ray and liquid crystal monitor.
cathode ray monitor. In such a monitor, the image is transmitted using a cathode ray tube (CRT). A CRT is an electronic vacuum device in a glass flask, in the neck of which there is an electron gun, and at the bottom there is a screen covered with a phosphor. When heated, the electron gun emits a stream of electrons that move at high speed towards the screen. The flow of electrons passes through the focusing and deflecting coils, which direct it to a specific point on the screen covered with phosphor. Under the influence of electron impacts, the phosphor emits light that is visible to the user. EL monitors use three layers of phosphor: red, green, and blue. To equalize the electron flows, a shadow mask is used - a metal plate with slots or holes that separate the red, green and blue phosphors into groups of three points of each color. Image quality is determined by the type of shadow mask used; image sharpness is affected by the distance between groups of phosphors.
The chemical used as a phosphor is characterized by an afterglow time, which reflects the duration of the glow of the phosphor after exposure to an electron beam. The persistence time and image refresh rate must be matched so that there is no noticeable flicker in the image and there is no blurring and doubling of the edges as a result of superposition of successive frames.
The electron beam moves very quickly, tracing the screen in lines from left to right and from top to bottom along a path called a raster. The horizontal scanning period is determined by the speed of the beam moving across the screen. In the process of sweeping (moving across the screen), the beam acts on those elementary sections of the phosphor coating of the screen where the image should appear. The intensity of the beam is constantly changing, as a result of which the brightness of the glow of the corresponding sections of the screen changes. Since the glow disappears very quickly, the electron beam must run over the screen again and again, renewing it. This process is called image renewal (or regeneration).
LCD Monitor. By borrowing technology from laptop display manufacturers, some companies have developed liquid crystal displays, also called LCD displays (Liquid-Crystal Display). They are characterized by a non-reflective screen and low power consumption (some models of such displays consume 5 watts, while monitors with a cathode ray tube - about 100 watts). Active matrix LCD monitors currently outperform most EL monitors in terms of color quality. LCD monitors use either analog or digital active matrices. LCD monitors larger than 15 inches provide both analog (VGA) and digital (DVI) connectors, which are found on many mid-range and high-end video adapters. A polarizing filter creates two separate light waves and passes only the one whose plane of polarization is parallel to its axis. By positioning the second filter in the LCD monitor so that its axis is perpendicular to the axis of the first, the passage of light can be completely prevented. By rotating the polarization axis of the second filter, i.e., by changing the angle between the axes of the filters, you can change the amount of light energy transmitted, and hence the brightness of the screen. The color LCD monitor has one more additional color filter; which has three cells for each image pixel - one for displaying red, green, and blue dots. The red, green, and blue cells that make up a pixel are sometimes called subpixels.
A dead pixel is a pixel whose red, green, or blue cell is permanently on or off. Always-on cells are very visible against a dark background as a bright red, green, or blue dot. LCD monitors come with active and passive matrix.
Most LCD monitors use thin film transistors (TFTs). Each pixel contains one monochrome or three RGB color transistors, packaged in a flexible material exactly the same size and shape as the display itself. Therefore, each pixel's transistors are located directly behind the LCD cells they drive. Currently, two materials are used for the production of active matrix displays: hydrogenated amorphous silicon (a-Si) and low-temperature polycrystalline silicon (p-Si). The main difference between the two is the production price. To increase the apparent horizontal viewing angle of LCD monitors, some manufacturers have modified the classic TFT technology. In-plane switching (IPS), also known as STFT, aligns LCD cells in parallel with the screen glass, applies electrical voltage to the planar sides of the cells, and rotates the pixels to display a clear and uniform image across the entire LCD panel. Super-IPS Technology - rearranges LCD molecules in a zigzag pattern instead of rows and columns to reduce unwanted color mixing and improve color uniformity across the screen. In a similar technology, multi-domain vertical alignment (MVA), the monitor screen is divided into separate areas, for each of which the orientation angle is changed.
In passive matrix LCD monitors, the brightness of each cell is controlled by the voltage flowing through transistors whose numbers are equal to the row and column numbers of that cell in the display matrix. The number of transistors (by rows and columns) determines the screen resolution. For example, a 1024x768 screen contains 1024 transistors horizontally and 768 vertically. The cell reacts to the incoming voltage pulse in such a way that the plane of polarization of the passing light wave rotates, and the larger the angle of rotation, the higher the voltage.
The cells of a passive matrix LCD monitor are supplied with a pulsating voltage, so they are inferior in image brightness to active matrix LCD monitors, each cell of which is supplied with a constant voltage. To increase the brightness of the image, some designs use a control method called double-scan, and its corresponding devices are double-scan LCD monitors (double-scan LCD). The screen is split into two halves (upper and lower), which operate independently, resulting in a reduction in the interval between pulses entering the cell. Dual scanning not only increases the brightness of the image, but also reduces the screen response time, as it reduces the time it takes to create a new image. Therefore, dual-scan LCD monitors are more suitable for creating fast-moving images.
1.2Printer
One of the purposes of a computer is to create a printed version of a document, or a so-called hard copy. That is why a printer is a necessary accessory for a computer. Printers (printing devices) - these are data output devices from a computer that convert information ASCII codes into their corresponding graphic characters and fix these characters on paper. The printer expands the relationship of the computer with the material world, filling the paper with the results of its work. In terms of speed capabilities, printers form a range from sluggish operation to light. They compete with plotters in the ability to draw graphic images. Today there are three types of printers:
Laser. A laser printer works as follows: an electrostatic image of a page is created on a photosensitive drum using a laser beam. Placed on the drum, a specially colored powder called toner "sticks" only to the area that represents the letters or image on the page. The drum turns and presses against the sheet of paper, transferring toner onto it. After fixing the toner on paper, the finished image is obtained.
After the data is loaded into the printer, the computer begins the process of interpreting the code. First, the interpreter extracts the control commands and the contents of the document from the incoming data. The printer processor reads the code and executes the commands that are part of the formatting process, and then executes other printer configuration instructions (such as paper tray selection, single-sided or double-sided printing, etc.).
The process of interpreting the data includes a formatting phase, during which commands are executed that indicate how the content of the document should be laid out on the page. The formatting process also includes converting the outlines of fonts and vector graphics to bitmap. These character bitmaps are placed in a temporary font cache, from where they are retrieved as needed for direct use in one place or another in the document.
As a result of the formatting process, using a detailed set of commands, the exact location of each character and graphic image on each page of the document is determined. At the end of the data interpretation process, the controller executes commands to create an array of points, which will then be transferred to paper. This procedure is called rasterization. The created point array is placed in the page buffer and stays there until it is transferred to paper. Printers that use stripe buffers divide the page into multiple horizontal stripes. The controller rasterizes the data of one strip, sends it to print, clears the buffer and proceeds to process the next strip (the page in parts falls on the photosensitive drum or other printing device).
After rasterization, the page image is stored in memory and then transferred to the printing device, which physically performs the printing process. Printing device is a general term for devices that directly transfer an image to paper in a printer and includes the following items: laser scanning unit, photosensitive element, toner container, toner distribution unit, corona, discharge lamp, fusing unit, and paper transport mechanism. Most often, these elements are structurally made in the form of a single module (a similar printing device is used in copiers).
Jet. In inkjet printers, ionized ink droplets are sprayed onto the paper through nozzles. Spraying occurs in those places where it is necessary to form letters or images.
The data interpretation processes for inkjet and laser printing are basically the same. The only difference is that inkjet printers have less memory and a less powerful computing system. Liquid ink is sprayed directly onto the paper - in those places where an array of dots is formed in a laser printer. There are currently two main types of inkjet printing: thermal and piezoelectric. The cartridge consists of a reservoir of liquid ink and small (about one micron) holes through which the ink is pushed onto the paper. The number of holes depends on the resolution of the printer and can range from 21 to 256 per color. Color printers use four (or more) tanks of different color inks (cyan, magenta, yellow, and black). By mixing these four colors, almost any color can be reproduced.
1.3Plotter
The task of displaying information presented in graphical form arose simultaneously with the advent of computing, and its solution is one of the main goals of computing tools used for design automation. Devices that perform the functions of outputting graphic information to paper and some other media are called plotters or plotters (from the English plotter).
Pen plotters
Pen plotters are electromechanical devices of the vector type. Graphic images are traditionally output to it, various vector software systems such as AutoCAD. Pen plotters create an image using writing elements, collectively called feathers, although there are several types of such elements that differ from each other in the type of liquid dye used. Writing elements are disposable and reusable (allowing recharge). The pen is mounted in a stylus holder, which has one or two degrees of freedom of movement.
There are two types of pen plotters: tablet, in which the paper is stationary and the pen moves across the entire image plane, and drum, in which the pen moves along one coordinate axis, and the paper moves along the other due to capture by the transport shaft. Movements are carried out using stepper or linear electric motors, which create quite a lot of noise. Although the output accuracy of drum plotters is somewhat lower than that of flatbed plotters, it satisfies the requirements of most tasks. These plotters are more compact and can cut a sheet of the required size automatically from a roll (A3 pen plotters are usually flatbed).
A distinctive feature of pen plotters is the high quality of the resulting image and good color reproduction when using colored writing elements. Unfortunately, the speed of information output in them is low, despite faster mechanics and attempts to optimize the drawing procedure.
Inkjet plotters
Inkjet imaging technology has been known since the 70s, but its true breakthrough became possible only with the development by Canon of technology for creating a reactive bubble (Bubblejet) - directed spraying of ink on paper using hundreds of tiny nozzles of a disposable printhead. Each nozzle has its own microscopic heating element (thermistor), which instantly (in 7-10 µs) heats up under the influence of an electrical impulse. The ink boils and the vapor creates a bubble that pushes a drop of ink out of the nozzle. When the pulse ends, the thermistor cools down quickly and the bubble disappears.
Printheads can be "colored" and have a corresponding number of nozzle groups. To create a full-fledged image, the standard CMYK color scheme for printing is used, using four colors: Cyan - cyan, Magenta - magenta, Yellow - yellow and Black - black. Complex colors are formed by mixing the primary ones, and obtaining shades of different colors is achieved by thickening or rarefying dots of the corresponding color in a fragment of the image.
Inkjet technology has a number of advantages. These include ease of implementation, high resolution, low power consumption, and relatively fast printing speed. Affordable price, high quality and great opportunities make inkjet plotters a serious competitor to pen devices, however, the low speed of output of graphic information and fading over time of the resulting color image without taking special measures limits their use.
Electrostatic plotters
Electrostatic technology is based on the creation of a latent electrical image on the surface of a carrier - special electrostatic paper, the working surface of which is covered with a thin layer of dielectric, and the base is impregnated with hydrophilic salts to provide the required moisture and electrical conductivity. The potential relief is formed when free charges are deposited on the surface of the dielectric, which are formed when the thinnest electrodes of the recording head are excited by high-voltage voltage pulses. As the paper passes through the liquid magnetized toner developing unit, toner particles are deposited on the charged areas of the paper. The full color gamut is obtained in four cycles of creating a latent image and passing the media through four developing nodes with the corresponding toners.
Electrostatic plotters could be considered ideal devices if it were not for the need to maintain a stable temperature and humidity in the room, the need for careful maintenance and their high cost, in connection with which they are purchased by users who have justifiably high demands on productivity and quality. For maximum efficiency, electrostatic plotters usually work as network devices, for which they are equipped with network interface adapters. Also important are the high resistance of the image to the effects of ultraviolet rays and the low cost of electrostatic paper.
Direct Output Plotters
The image in such plotters is created on a special thermal paper (paper impregnated with a heat-sensitive substance). Thermal paper, which is usually fed from a roll, moves along the "comb" and changes color in places of heating. The image is of high quality (resolution up to 800 dpi (dots per inch)), but only in monochrome. Due to their high reliability, productivity and low operating costs, direct image output plotters are used in large design organizations to output verification copies.
Thermal Transfer Plotters
The difference between these plotters and plotters for direct image output is that they place a "donor color carrier" between the thermal heaters and the paper - a thin, 5-10 micron thick tape facing the paper with an ink layer made on a wax base with a low (less than 100 ° C) melting point.
On the donor tape, areas of each of the primary colors are sequentially applied in a size corresponding to the sheet of the format used. In the process of outputting information, a paper sheet with a donor tape superimposed on it passes under the print head, which consists of thousands of tiny heating elements. The wax melts in places of heating, and the pigment remains on the sheet. One color is applied in one pass. Its image is obtained in four passes. Thus, four times more ink ribbon is spent on each sheet of a color image than on a sheet of monochrome.
Due to the high cost of each print, these plotters are used as part of computer-aided design tools for high-quality output of 3D modeling objects, in cartography systems, and by advertising agencies to output color proofs of posters and banners for colorful presentations.
Laser (LED) plotters
These plotters are based on electrographic technology, which is based on the physical processes of the internal photoelectric effect in light-sensitive semiconductor layers of selenium-containing materials and the force of the electrostatic field. An intermediate image carrier (a rotating selenium drum) can be charged in the dark to a potential of hundreds of volts. A beam of light removes this charge, creating a latent electrostatic image that attracts the magnetized fine toner, which is then mechanically transferred to the paper. The toner-coated paper then passes through a heater, whereby the toner particles are baked to form an image.
Due to their high speed (A1 format sheet is output in less than half a minute), laser plotters are convenient to use as network devices, and they have a network interface adapter as standard. Just as important, these plotters can run on plain paper, reducing operating costs.
1.4 Projector
A projector is a lighting device that redistributes the light of a lamp with a concentration of light flux on a small surface or in a small volume. The main element of any projector is a lamp, the light of which, passing through certain elements, hits the screen and thus forms an image. Depending on which elements the light from the lamp passes through, the projectors are divided into LCD and DLP(micromirror). The advantages of liquid crystal projectors include less negative impact on vision, as well as compactness. Their disadvantage is insufficiently saturated black color (owners of LCD monitors will understand what is at stake). The advantage of micromirror projectors is a better picture, and their main disadvantage is considered to be visual fatigue during very long viewing.
Like any technical device, projectors have characteristics that you should pay attention to first. Firstly, this is the so-called "basic graphics resolution". It is indicated by two numbers, reflecting the number of dots horizontally and vertically. Like monitors, the resolution is 800x600, 1024x768, etc. up to 1600x1200. Of course, the higher the resolution, the better the picture quality will be. For a home projector whose main task is to watch movies, a resolution of 800x600 will be enough. This is due to the fact that films designed to be viewed on a TV screen have an even lower resolution, so 800x600 is already quite enough. Secondly is the brightness of the projector. The brighter the projector, the better. If the brightness is too low, you may need to completely darken the room for comfortable viewing. And a brightness of 1000 lumens (a lumen is a unit of measurement of brightness) will be quite enough for home conditions, lower values are almost never found today. In this case, the operating conditions of the projector must be taken into account. If it is installed in a separate room with the possibility of complete dimming, then such a parameter as brightness is not too important. If the projector is planned to be used in a living room where it is difficult to achieve complete darkness, then such a parameter as brightness should be paid attention to. Thirdly- projector contrast. With a low contrast ratio, dark scenes in films may simply not be visible. The contrast ratio of a home video projector should be between 1000:1 and 2000:1.
1. 5 speakers
Speakers, or an acoustic system, is another information output device that connects to a computer (there is an input jack on the back of the motherboard) and serves to play sound effects, music, movies, etc. Currently, there are two principles of acoustic systems: active and passive.
There is an opinion that active acoustics used mostly by professionals, although it also connects to computers. The sound is sent from the dvd player through the amplifier (receiver) straight to the speakers of the speaker system. Amplification of the sound signal plays one of the key roles in this process. How can sound be amplified? There are two ways. The first this is when, before being fed to the speakers, the sound signal enters the amplifier, and second- using the speaker system itself, in the speakers of which the amplifier is built.
In addition to this, the design of active acoustics allows you to provide feedback between the amplifier and the speaker. This allows the amplifier to change the load on the speaker during maximum load and prevent damage to the latter. Due to the fact that the amplifiers and speakers in active speakers are connected directly, the maximum performance of the speaker system is achieved. This provides a very good sound output with small acoustics. Active speaker systems for home use usually consist of a subwoofer and a set of 5 satellites. The subwoofer has a built-in amplifier, which is distributed over six speakers.
But active speakers have a minus - the impossibility of modernization. Such an acoustic system will always sound the same. The significance of this fact is very significant. Having become interested in acoustic systems, the buyer turns into a lover of sound technology and tries from time to time to improve the sound quality of his home acoustics. Therefore, the owner of active acoustics will have to come to terms with the quality of the sound produced with its help once and for all. Active speakers try to make initially high level.
At work passive speaker system the built-in crossover heats up; it takes on a fairly large output power. Manufacturers try to avoid this in various ways, but the main thing is to understand the essence of this process. The amplifier sufficiently loads the electronics of the acoustic system, as a result of which the quality of the output sound, just like the characteristics of passive speakers, change. If the speakers are used in a home theater, then the amateur is unlikely to hear the difference. But for a professional, this difference will be quite critical. Passive speakers need to be slightly more powerful than the amplifier in order to cope with the power delivered to them at critical moments. Otherwise, when the amplifier is more powerful than the acoustics, the speakers may simply fail. Passive speakers can't provide feedback to the amplifier to deliver less power, and it can't track the load itself either. Despite the drawbacks, a passive speaker system isn't all that bad. Most buyers of acoustic systems buy it for a home theater, computer, and at home, as you know, comfort and coziness are very much appreciated. Active acoustics require a separate power cord to be connected to each speaker. So connecting all active speakers to the network can be a very confusing task. The next point is much more important. Since all acoustic systems are divided into classes, when using passive acoustics, it is possible to upgrade the system over time by purchasing a new amplifier and receiver. The sound quality of good passive speakers can improve significantly. Therefore, when choosing passive acoustics, speakers can be taken, as they say, "for growth."
Chapter 2 Input Devices
2.1Keyboard
Now the main widespread input device
in a computer is a keyboard (key device). She realizes
dialogue between the user and the PC:
Entering user commands providing access to PC resources;
Recording, correcting and debugging programs;
Entering data and commands into the problem solving process.
The MFII keyboard standard has now been adopted. Conditionally in it
it is possible to single out five groups of keys that carry their functional shipment.
From other types of keyboards, special keys can be mentioned for
blind with tangible dots on the keys; keyboards for stores and
warehouses equipped with barcode readers or
reading magnetic cards; industrial keyboards - touch, having in
as protection against harmful influences (chips, ash, etc.)
additional covering of keys with a special touch foil; keyboard
for medical institutions with devices for reading information from
insurance cards. Currently there are keyboards with additional
keys for the convenience of working with a particular operating system (OS),
e.g. keyboard for Windows 95.
Thus, the choice of keyboard depends on the OS with which
supposed to work.
2.2Mouse
It is used to enter data or single commands selected from the menu.
whether textograms of graphic shells displayed on the monitor screen.
The mouse is a small box with two or three
keys and recessed, freely rotating ball in any direction
on the bottom surface. It connects to the computer with
special cord and requires special software support.
The mouse requires a flat surface to work with.
use rubber mats.
Since the mouse cannot enter a series of commands into the computer,
therefore, the mouse and keyboard are not interchangeable devices. Purpose
graphical shells - in ensuring the initialization of many commands without
prolonged typing from the keyboard. This reduces the chance of typos and
saves time. On the object in the form of a tectorgram, a menu item is selected or
character and mouse click is initialized. Of course, when typing or
some functions, the use of the mouse may be irrational,
if, for example, these functions are performed by pressing the function keys.
At present, there is also an optical mouse, where the signal
transmitted using the mouse beam to a special mat and analyzed
electronics. While tailless (cableless) is less common
infrared mouse (the principle of its operation is similar to the operation of remotes
remote control) and radio mouse.
In portable PCs (Lapton, Notebook), the mouse is usually replaced with a special built-in
into the keyboard with a ball on a stand with two keys on the sides, called
The principle of its operation is the same as the principle of the mouse. In spite of
the presence of a trackball, a user of a portable PC can use a regular
2.3 Scanners
For direct reading of graphic information from paper or
other media in the PC uses optical scanners.
The scanned image is read and digitized
elements of a special device: CCD - chips.
There are many types and models of scanners. Which one to choose
depends on the tasks for which the scanner is intended.
The simplest scanners recognize only two colors: black and white.
These scanners are used to read bar codes.
Handheld scanners are the simplest and cheapest. The main disadvantage is
that the person himself moves the scanner around the object, and the quality of the resulting
image depends on the skill and firmness of the hand. Another important disadvantage is
small width of the scanning strip, which makes it difficult to read wide
originals.
Drum scanners are used in professional printing
activities. The principle is that the original on the drum
illuminated by a light source, and photosensors convert the reflected radiation into
digital value.
Sheet scanners. Their main difference from the previous two is that
when scanning, a ruler with CCD elements is fixed, and the sheet
with the scanned image moves relative to it with the help of special
Flatbed scanners. This is the most common form for
professional works. The object to be scanned is placed on a glass sheet,
the image is read line by line at a uniform rate by the read head with
CCD - sensors, located below. The flatbed scanner can be
equipped with a special slide attachment for scanning
transparencies and negatives.
Slide scanners are used to scan microimages.
projection scanners. Relatively new trend. Color projection
The scanner is a powerful multi-functional tool for entering into a computer
any color images, including three-dimensional. He may well replace
camera.
Nowadays, scanners have another application - reading
handwritten texts, which are then used by special recognition programs
characters are converted to ASC II codes and can be further processed
text editors.
Conclusion
In this control-course work, sufficiently detailed information was provided on the output / input devices of information and on the principles of their operation. The operation of a modern computer cannot be imagined without equipping it with the above devices, since they provide indispensable assistance when a user works with a computer, and knowledge of the principles of operation of these devices ensures their more efficient use.
Conclusions on the performed laboratory work. During...
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Abstract >> InformaticsParts: device input information processing devices information device storage device output information. Structurally, these... Additional devices can be connected input and output information such as speakers, printer, ...
