TYPES OF MONITORS
Displays (Monitors) – visual equipment for the information entered, and are derived from a personal computer display. Main characteristics – resolution. The letters on the screen made up of points, called pixels. In the letter to be seen, the computer sends a “enabled” or “off” code to each pixel within the graphic card. The letters of the bright pixels and spaces between them. After more points and make them smaller, of less space, and increased brightness. Resolution is measured at the measured number of pixels on the screen (horizontally and vertically). The higher the number – more brightness.
Each display can be operated in two modes:
1) text – display relatively divided into 25 lines of 80 characters each. In fact, the line can accommodate 256 characters. Some modifications of monitors can not be 25, but 43 (EGA) and 50 (VGA) lines. Showing the location of each symbol may correspond to its own color of it to multitone records.
2) the graphic – to the screen image can be derived, ie graphical complexity of the object image.
The display screen can be a special filter, which is:
• reduces reflections and flicker in public;
• improves the video quality;
• protect against radiation;
• reduces the electric field.
LIQUID CRYSTAL DISPLAYS
In 1980 year at the end of the first portable personal computers. The key factor, allowing the computer to significantly reduce the weight of the liquid crystal display (Liquid Crystal Display, LCD) uses. Such a display screen consists of two glass plates, between which is the mass of the liquid crystal, which can change its optical structure, the location and characteristics of the electric field acting on them. Crystal movement agrees relatively high resistance, so to change their situation can only be closed to a certain speed. The first color display Response time was up to 500 ms. Using DSTN (Dual-scan Super Twisted Nematic) technology, and special liquid crystals the reaction time shortened to 150 ms. Company Toshiba, using TFT (Thin Film Transistor) technology, has made the display, which almost did not monitor with the electron tube (the reaction time of 50 -75 ns). LCD is used for organic material from the long parallel molecules, the orientation can be modified by special treatment, the internal screen surface and the electric field. The image on the screen changes the voltage controlled variable transparency of the cell. Passive monitors for the display is dark outside, so it appears black transparent cells and opaque light. Active monitors vice versa. Color video monitors one point that even the three display cells, the R, G and B filters.
Liquid screen monitors are thin, flat, rectangular shape and regular don‘t blinking. One of the largest LCD (liquid crystal display) deficiency (excluding price) is the angle of vision: the best is the status, the more driven of the monitor, the more difficult to discern the image on the screen. LCD monitors are placed in portable computers, however, to make an LCD monitor at home, yet need to improve the image quality and reduce cost.
Plasma displays structure similar to the LCD display, only instead of liquid crystals used in the gas mixture, which is exposed to electrical pulses glow. The quality of the video monitors around the same area of the screen, they don‘t blink, in addition, the display area of almost unlimited. Disadvantages – they need to work a large e-mail and the current high price (yet). Color plasma display consists of an inert gas filled and the inside cover liuminofor cells. Plasma screens are active, because “ignited” inert gases, they emit ultraviolet rays, which seasoning red, green or blue emit liuminofor. Screens operated by coordinating suppress alternating voltage to the opposite side of the screen, and oriented perpendicular to the display of rows and columns in the electrodes. Such screens should be relatively high voltage (one hundred volts), in addition, has so far failed to produce the display, which points to a diameter of less than 0.3 mm. Corporate “Akai” made a TV 84 mm. the thickness of one meter with LCD screen displays 852×480 pixels resolution and 16 million colors.
The first monitors were monochrome, i.e. each point can only be black or white (the best case, the point may be different glow brightness). These monitors are intended for the video card has two types:
Herkules monitors can display only a black or white points, a maximum resolution of 728 * 348 pixels. They can only work with the video card, because of the monitor receives the scanning sinchro pulses, without which the monitor is closed.
Date TTL (Transistor Transistor Logic) is a standard digital chips used in electronic equipment, the series. TTL monitors the video card gets a digital signal. However, in a way interaction of the video card and monitor, shades of each individual is required to forward broadcasts. How should it look like connecting the cable to be transmitted to a 16-million colors palette?! Therefore, the digital displays almost no longer used.
It monitors, video cards, which receives the analog video signal. Such a signal issue, all the video cards, starting with a VGA capable of maintaining 640 * 480 or greater resolution. VGA displays can work not only in color, and monochrome mode. In this case, the color and tone replaced by shades of gray. Monochrome display, as a rule, used only the green video signal. Red and blue color signals are not.
In order to monitor and video adapter to work together, it is necessary to synchronize them. Synchronization – two or more elements in alignment with time. The video card is issued by the Sync signals – the lines and frame synchronization. Both of these signals have different meanings to the monitor must be recognized.
All modern monitors can be divided into three broad groups:
1. With a fixed frequency;
2. With a number of fixed frequencies;
Displays with a fixed frequency is aware of any frequency sinchroimpulses, for example, 60 Hz frame scan, the lines – 31.5 kHz. Displays the number of fixed frequencies can work with a number of shots and lines of the synchronization frequency sets. Multifrequency (sometimes called multisync) displays are able to work with any frequency sinchrosignals from the specified range, 64 kHz, and lines 50 – 100 Hz frame scan.
Picture of the CRT-type monitor drawing electron radius. Pixels luminosity and hue depends on the radius of the electron intensity. Respect the view from the top to bottom and from left to right.In coloured screen picture drawing of three beams (one for each color – red, R (red), green-G (green) and blue B (blue)). The monitor is often referred to as the number of frames per second drawing. That the radius of the electron wake up only one type of liuminofor tube, to monitor the metal mask, the beam is narrow. Since the radius in width, the screen size and the mask of the monitor resolution, measured in number of pixels per line and column (eg: 800×600 – the line is 800 points, and the column of 600). One of the key parameters of the screen is the distance between the points (DP-Dot Pichu). What is less the better. The current monitor is a dp of 0.24 to 0.28 mm. The smaller the distance between the points of the image clearer. But that is not enough. That the image on the screen would be good, even necessary and good vertical and horizontal scanning frequency. The current screens the horizontal scanning frequency range from 27 KHz to 107 KHz, and vertical scanning frequency from 47 Hz to 180 Hz. However, the maximum parameters is not the best, the most common monitor resolution is determined by the road-inch diagonal display is and the frequency is determined so that the view of the monitor screen don‘t blinking.
POPULAR KINESCOPE TYPES IN CRT DISPLAYS
CRT (catod ray tube) monitors – the standard monitors with large tubes. However, the tubes are of different types and it is up to them to monitor quality.
Tube type. Features
DynaFlat (bulbous tube before it is flatron glass)
Trinitron, Diamondtron tubes
In the corners distortion
Reflected directly in front of the screen and the sides of the light sources.
|Reflected directly in front of the screen and the sides of the light sources. Reflections double.|
Reflected directly in front of the display of the light sources.
Reflected directly in front of the display of the light sources.
3. View quality
Better displayed small details.
More pronounced in color and contrast, but is visible in one or two horizontal lines.
Distinctly visible from near the grain.
4. Displays makers.Hansol, MAG, CTX, Sampo, …Samsung, CTX, MAG, …
Sony, CTX, NEC, …
1.View distortion. Convex distorted picture of the display.
2. Reflections. Convex reflects directly in front of the monitor screen and the side of the light sources. How will reflect from the side of the monitor salience of the different models are different.
DynaFlat display reflects the slightly less convex than the monitor, but because of its structure is double reflection on the screen.
Trinitron display reflects only the screen directly in front of the light sources, and unlike Dynaflat almost not doubling reflections.
Flatron display reflect only the screen directly in front of the light sources, and unlike the remaining tubes not doubling reflections.
DynaFlat type displays a well view small details, and therefore suitable for drawing, not a specific color coordination.
Trinitron displays,as a type of color more lush, contrast more pronounced, therefore, suitable for working with colored pictures.
Flatron displays, the type of the image looks grainy close.
Convex displays does not have any critical features.
4. Price. Convex displays are cheapest, and the Trinitron and the Flatron – precious.
LIQUID CRYSTAL DISPLAY SCREEN TYPES
Computer monitors lucent used in the manufacture of TFT LCD screens. The light source is installed on the sides of the screen consists of fluorescent lamps, and a complex optical system for light to align the screen.
Color image obtained from the lamps to light during the transition of liquid crystal matrix, composed of adjacent cells controlled transparency with red (R – Red), green (G – green) and blue (B – Blue) filters. The transparency of each cell on a separate thin-film transistor (Thin film transistor – TFT).
Produced three main types – TN + Film (Twisted Nematic + Film), IPS (In-Plane Swiching) and MVA (Multi-domain Vertical Alignment), and various modifications of liquid crystal displays. Cheapest and most common – TN + Film.
The liquid crystal display cell filled with material having a fluid (a molecule can move each other) and the crystal (molecule may consist of monocrystalline domains) properties. Not matted screens used in liquid crystal, the long molecule located parallel to each other. The molecular orientation and the light emanating through the cell can change the polarization electric field. Liquid crystals are among the polarizotor who spends a certain polarization of the light. Polarizator of liquid crystal and the electrodes to the glass.
Cells treated with the internal surfaces, so that a direction-oriented liquid crystal molecules. The connection voltage change of the liquid crystal molecule orientation, the polarization properties of the cell, and transparency.
First, was created of TN screens. These transparent electrodes located on opposite sides of the cell. Electrode surface treatment so that, in the absence of voltage between the electrodes, situated adjacent to the electrodes of liquid crystal molecular orientation coincides with polarizator emanating through the plane of polarization of light.
TN on opposite sides of the screen polarizators oriented perpendicular to one another, the distance between the electrodes is chosen so that the passage from one cell to another electrode of liquid crystal molecules turn up 90 degrees. When the voltage is not available, the light spreading liquid crystal polarization plane of the swing 90 degrees, and the light in the second polarizator out of the cell – the cell becomes transparent (on screen – bright). The connection of tension, the liquid crystal molecules oriented vertically, don‘t turn light polarization plane and the second polarizator transmission of light – the cell becomes opaque (the display – dark). Cells are regulated by the transparency of the screen changing the molecular orientation angle, depending on the cell electrodes supply voltage level.
TN-type displays in the cell molecules failed oriented vertically, it spent a little light and a black screen instead of the point was to see the gray. As a result, the screen image contrast was relatively low, and the video viewing angle – just 90 degrees.
All types of TN screens have one major drawback: the failure of cell control transistor, all the time, it remains transparent, and displayed a dark background is visible a white dot.
TN + FILM-TYPE SCREENS
Since TN displays are different in that the screen surface is covered with a thin film in high-angle up to 140 0. Due to improved production technology on modern TN + Film displays show a contrast (up to 450:1) view. Inertia reduced to several milliseconds. Such screens suitable for dynamic games to play.
IPS display cell of the TN in that the liquid crystal molecule orientation control electrodes in one plane, and polarizators targeted equally. In the event of a failure of transparency in management of the transistor cells display a defect more difficult, polarizators and the liquid crystal molecules perpendicular to target throught polarizators undergone the light polarization plane. When there is no tension, the cell is an opaque screen (the display – dark). The connection of tension, the liquid crystal molecules turn angle of 900 and the cell becomes transparent.
IPS screens advantage in that their angle of vision reaches 170 0 (similar to the tube), in addition, it plays better contrast and color. However, IPS panels are inerted for TN + Film, so not suitable for dynamic games, although the manufacturer states only several milliseconds inertia. Monitors with the IPS screens are more expensive than with the TN + Film.
MVA TYPE SCREENS
MVA is the best type of screens, a relatively large viewing angle (160 – 170 degrees) and low inertia (20 ms or less). However, the design and manufacturing complexity, they are valuable. MVA screens in cells of electrodes located on opposite sides of the cell (as in the TN-type displays).
When the voltage is not, polarizator and the liquid crystal molecules as a focused and IPS screens, so the management failure of the transistor cell remains dark.
The connection of tension, the liquid crystal molecules in a vertical focus, it does not change the polarization of light and the cell becomes transparent. Such cells is that, consistently changing the management of all the tension in the liquid crystal molecules in the vertical position is changing in one direction. Therefore, without special measures the screen brightness depending on from which side of the screen is viewed.
Viewing the screen brightness angle of impact can be reduced in view of each cell by dividing the screen into two or four parts (chambers), the cell molecule pivot in opposite direction, and the average transparency of the cell, independent of viewing it in the direction.
This is achieved through the production of screens from the cells with a more complex profile of the inner surface.
The picture shows how the MVA-type screen luminosity depends on the viewing angle to the screen, where a cell consists of one-and two-chamber, and the supply side of the electrodes in the management of stress.
The two-camera cell phone is a gray screen and the viewing angles, both from the left or right side, as the eye can see in contrast to the viewing angle of camera light responsive cell mixture.
Monitors with LCD display takes up less space, use less electricity, their display is the perfect summary of more color image. However, such displays slightly worse plays in changing the colors and resolution may distort the picture.
Display diagonal.Diagonal – the distance between the bottom-left and upper right hand corner of the screen. This can be measured in centimeters or inches. However, you can not confuse the picture tube and the diagonal of the screen working area of the diagonal. Diagonal tube may be equal to or greater than the working area diagonal. The reason is that the working area are not included in the black box at the edge of the screen dimensions, which determines the electronic tube design. As long as the tube not hot, its edges should be approximately 5 mm wide, dark band. It is required for the tubes that the hostages remain on view in the box outside.
The screen mask. The video quality is very dependent on the mask type and characteristics. Gap between the mask holes is measured in millimeters. S 14-inch screen mask, which Sztum between holes 0.28 mm, has approximately 600,000 holes. What is the distance between the holes below the hole, and the more the better image quality.
Resolution.It depends on the distance (pitch, dot-pitch, Tri-dot-pitch) between the two nearest pixels, color picture tube – between the triangle centers, in millimeters.
The minimum acceptable distance in mm, between points of different resolution screens.
Diagonal screen size in inches
Current power. The more energy absorbed by the monitor, the more he scoured. A good 14-inch monitor has the use of 60 W el. energy. If such a monitor is used by more than 80 watts, it is more suitable for space heating.
Radiance, and filters. Acting on the monitor blinking quite a wide range of radiation: X-ray, infrared, radio, as well as the electrostatic field. Medical research has shown that these rays have negative effects not only the employees computer, but also the surrounding health. These factors reduce the impact of filters. The filters are of three types:
Grid filters are not bad protects the screen from the external light reflections, but does not protect completely against electromagnetic radiation and static electric fields. Filters does not protect the cells from the electrostatic fields, but significantly increases the image contrast, completely removes the display of ultra-violet radiation and reduce the intensity of the X-ray radiation. Good quality glass filters are totally eliminate reflections and a half – two-fold increase image contrast, eliminates electrostatic field and ultra-violet radiation, greatly reduces the low-frequency magnetic field and X-ray radiation . Currently popular LR (Low Radiation) screens with a radiation level of not more than:
Static electric field potential of + / -500 V
Dynamic electric field, the frequency of 5 – 5000 Hz voltage 0.5 m from the screen 25 V / m
Dynamic electric field, the frequency of 5 – 400 kHz voltage of 0.5 m away from the screen of 2.5 V / m.
Videomemory.How videomemory required quantity of the color shown in the table. Using three-dimensional graphics, amount of memory required increases significantly (for example, at a minimum resolution (640 * 480) and the maximum quantity of colors (16.7 million) requires 4 MB videomemory).
Monitor the operation of the electron tube is not very different from the simple principle of operation of the TV. It is as follows: Cathode blinked electron beam placed on the screen, an overlay of luminofor, makes it glow. Electron beam on the road are usually additional electrodes: a modulator that regulates the electron beam intensity (and hence the image brightness) and the targeting system, allowing the fiber to change the direction of movement (up – down and left – right).
Any view of the monitor screen consists of a large number of retro-reflecting luminofor points. Electron beam scan periodic full-screen, giving it close to each other positioned in the scanning lines. Electron beam moving lines, video, fed into the modulator, changing the brightness of pixels glow of shaping the image on the screen. Monitor resolution is determined by the points that he can play vertically and horizontally, the number of, for example. 1024 * 768.
Frames forming the monitor used for special signals. Scaning radius of the electrons moving in zigzag from the upper left toward lower right hand corner of the screen. Radius of movement for the horizontal direction “responsible” line scanning signal (H. Sync) for the movement of the vertical direction – Frame scanning (V. Sync) signal. The radius of the transfer line from the right extremity of the point to the next line the left side of the point (horizontal return stroke) and the last line of the right edge of the first line the left side of the point (the vertical return stroke) performs a special course of the inverse signal. In this way, the most important display settings are:
• Frame scanning frequency;
• Line scanning frequency;
• video tape capacity.
That the human eye in a single motion illusion, is not less than 24 Hz. Frame rate monitors are especially important, since it belongs to the screen flicker, and to belong, as soon is tired human eyes work computer, so PC monitors often seek to maximize the efficiency: the higher it is, the more stable image, and therefore, the less eyes.
However, increasing the frame rate required to increase the frequency of scanning lines, which reduces the time for each image point to form. The lines of scanning frequency (kHz) is determined by multiplying the frame rate of the number of lines.
Video bandwidth (Bandwidth, MHz) determine the frequencies of the most video. Most of the monitor signal with a frequency band for a “margin”, so in practice to monitor this parameter can be ignored.
COLOR VIEW FORMATION
Color monitor personnel making the same as for monochrome. Any color can be broken down into three (for example, red, yellow and green) components. This allowed the color television screens and the use of additive color mixing method for color image received. Illuminant display all three colors at a time, the obtained color image. Replacing all the main colors to be extracted all the intensity of the color range (from full black to full white). Human visual characteristic close to each other in the small details of the color of the distance, appeared as a single color spots on the monitor allowed the electron tube of a color image forming element of the three adjacent points situated luminofor. Color monitor has three electron tube electron guns with separate management schemes, and the inner side of the screen covered with luminofor the three main colors: red – R (Red), blue – B (Blue), and green – G (Green). Thus, each electron gun to “shoot” only in its color luminofor points. To each tube is colored mask which ensures that each cannon fall only electrons in the corresponding color luminofor.
Luminofor amount of points needed to ensure the requirements to the resolution depends on screen size: the more points should be placed, and the lower screen, while the points are more densely.
Under the same conditions, the monitor image brightness at the higher, the lower inner side of the screen dimensions luminofor pixels (dot pitch). The amount of points, more precisely, the distance between them, called a step, and different models of monitors are from 0.25 mm to 0.41 mm (high monitors – not more than 0.28 mm).
To find out what mode the monitor can work to distinguish the individual points, it is necessary to determine the amount of points at the monitor for the different working modes. A simple 14 “monitor’s screen width is about 265 mm. 640 * 480 dpi mode requires 640 pixels per line. Thus, the distance between the points must be not more than 0.41 mm.
SONY TRINITY TECHNOLOGY
Inside the monitor is an electronic tube (CRT – cathode ray tube), which is an electron “gun” and a mask – a grid. Display of internal luminofor coated layer. The image, which we can see the monitor screen, formed for the electron “guns” electron flow (beam), which is targeted to a specific screen location. Luminofor off the layer of electrons caused by the momentary glow of the screen. The image rays generated in a line after line, from left to right, from top to bottom – moving the entire screen within seconds.
Luminofor layer also creates a color image. When the radius of the strike, certain colors luminofor, he begins to emit the appropriate color of light. All the colors extracted by using the three luminofor – red, green and blue (RGB – Red, Green, Blue). Three different intensity of color produced by the whole spectrum of colors. In order to direct the beam to the required layer luminofor place screens used masks (mask). Trinitron monitors, this mask is known as the lattice Aperturre Grille. Sony Trinitron monitors view more pronounced than the other, since the built-in radius of the landing control system. Trinitron uses Super-Fine-Pitch grill with vertical and very narrow slit , which directs the precise electron beam through a mask to the appropriate layer luminofor share.
Formed Trinitron picture tubes are very clear and bright. A simple metal plate used in tubes with small holes,reduce radiation intensity, the brightness of the video.
Corporate SONY tubes apart from other companies products that they are always cut from the cylinder . And not from the ball, and it reduces the image distortion.
SONY TrinitronTM another feature is that they, unlike the conventional capable tubes with crack mask, must not three, but only one electron tube with three cathode and bringing plates grill made from the carcass stretched thin metal strings. This type of mask ensures the objectives of the radius of the target luminofor, it is also very little deformation of the temperature, the less distorted colors. This type of lattice almost “transparent” the flow of electrons, resulting in increased image brightness. SONY Company produces several types of monitors with the tube: this is SONY TrinitronTM – one of the first monitor with a flat tube. sony black trinitronTM – it trinitron with a dark front glass, ensures increased image contrast. They use special S – beam pipe with a “panoramic” focus, to improve the visual focus.Sony black trinitronTM – Black TrinitronTM improved, it is the windscreen has more black and further increase the image contrast, the light absorption, rather than reflecting it. Super Black TrinitronTM – the old Black TrinitronTM type of tube, only flattening. These tubes used for “Super Pan Focus”-type electron tube significantly reduces the flow of electrons in diameter, resulting in a significant increase in screen resolution.
LUMINOFOR SCREEN COATING
Luminofor described the quality of the chemicals from which it was made, the quality and characteristics. Cheap chemical compound used in the particles, and the glow of a flow of electrons,but has a low residual glow. Points to glow until the radius of the elektrons scan full screen and re-activize creation of pictures that represent a point in the next frame. So, this time must not be less than the frame period of change – 20 ms. Failure of this requirement in video flicker. Using the high quality expensive materials to avoid it. Each point shines equally as far as time is needed to electron beam scan screen. The image displays, these have a high quality luminofor are contrasting, completely clean and not blink. The flow of electrons must have energy, which are sufficient to compel luminofor points glow. This ensures the appropriate anodic and faster electron tube voltage.
Monitors, from VGA to the analogue interface, the signal from the computer is analog. This allows a large amount of colors. Synchronization signals remain in digital TTL-level signals. VGA and SVGA general principles of operation of the same, differing only by the maximum resolution, scanning frequency and significance.
RGB monitor connector has 15 contacts:
Red colours video signal
Yellow colour video signal
Blue colour video signal
DDC serial data
Horizontal (line) synchronization
Vertical (frame) synchronization
Monitor the structural scheme
PC display, as the TV screen, a picture paints glowing point, runing through the screen. Electronic point of the electron tube radius, wake up the inner side of the screen covering luminofor. From the radius of the intensity of the pixels of the image brightness.
The monitor screen image is almost always painting shot, and not as snapshot TV. Scenes emission rate ranged from 60 to 150 Hz.
Most modern display automatically adapts to the graphic display of information standards, using different lines and the frame dissemination frequencies.
The video quality of the display screen is very dependent on the tube resolution. What makes it more, the clearer picture.
Visual flicker on the screen depends on the frame frequency of dissemination. The higher, the less blink view, and the less it is very eyes.
Is the brightest displays with the Trinitron-type tubes with a transparent mask.
Small detail better displayed display, a wider bandwidth (Bandwidth).
Display screen brightness decreases approximately two times at 10 – 15 thousand hours of operation.
Display healthier when jeme the image changes, so the program, generating moving images (Screen Saver) increases the monitor’s service time