Computer Monitor

 Back  I/O Equipment  Next


 RGB Computer and meant for a specific or general output device is a display of the results or conditions and one of the most famous MONITOR. The term itself refers to the control and monitoring of a process, that is usually a distinctive pictorial insight into the state of the eye. However, this term is usually applied to computers in general and meant for display device that draws some of the techniques on his SCREEN. So, the correct interface leads to monitor analog or digital video signal from a computer graphic system, which is logical and appropriate control electronics into a visible image on the screen. They further described the most common technology used for this purpose. All of them are based on ADDITIVE color mixing process, mixing three primary colors of light beams; Red, Green, Blue - RGB.

CRT (Cathode Ray Tube) monitor light beams of different color phosphors obtained by particle bombardment inside the monitor screen stream of electrons. If the stream contains multiple electron excitation phosphor particles is stronger and more light. To obtain color images are used to group particles of three elementary particles, each of which emits a beam of light one of the primary colors, red (R), green (G) and blue (B), which give color mixing that around recognized as unique. If the particles are less physically phosphorus, therefore, a better view because the image is composed of several individual elements.


Example XII

Displaying the image on a CRT (Cathode Ray Tube) and LCD (Liquid Crystal Display) monitors.

 CRT monitor - construction    LCD monitor - construction
Figure** 3.3.29 Plotting images on the CRT. + / - ) Figure** 3.3.30 Plotting images on the LCD.

A set of three adjacent points phosphoric different color on the inside of the monitor screen is called the elementary RGB TRIODE - PIXEL. The spacing between adjacent dots of the same color between two adjacent triode (dot pitch / pixel pitch) on the screen CRT monitors for common diagonal size of 15"-22" to be 0.20 mm-0.30 mm (white arrow in Figure 3.3.29c), which is roughly around 1200-3000 triode along horizontal axis monitor. The more dots per unit area of the monitor screen is higher quality but more expensive. Element of the picture that is displayed on the monitor would not by size should be less than the basic RGB triode on screen. Today it is common to work with resolutions up screen of 1024768 pixel or more, which means that one pixel in the image is associated with many triode monitor screen, which gives a lot of high-quality images. If used in image resolution such that the pixel image is less than or equal to the physical size of RGB triode display on the monitor will be substandard. Only diagonal monitors 17" and size of RGB triode 0.22 mm can be well reproduced image resolution of 16001200 pixels. Signal for monitoring the electron beam is ANALOGOUS and monitors usually have VGA 15-pin connectors (name no association with XGA, VGA and SVGA mode image display).

So, the basic element in creating the image PIXEL is composed of three sub items (subpixel). Form of pixels does not necessarily have to be round. Provide greater efficiency phosphor striped tape on the screen instead of the sieve which precedes the mask named TRINITRON truss structure that looks like a triode arrangement at the LCD monitor, but the performative expensive. Among the solution in the form of rectangular picture elements called IN-LINE provides results in quality between the described solutions. These solutions schedule subpixels in triode is shown in Figure 3.3.29c. Good peculiarity TRINITRON and in-line solutions to the CRT electron guns are not in relation to the ethmoid mask spatially arranged with each other at an angle of 120 and at a slight angle to the vertical line that comes out of the center of the sieve masks electron guns (axis CRT), but are in the same horizontal plane in which the axis of the CRT and the one of the guns is exactly on the axis of the mask sieve or grid. Thus greatly simplifying the electronics that must be corrected the distortion caused by the different position of the electron gun the axis of the CRT. Form and structure of names of phosphorus on the screen for the three types of monitors are shown in Figure 3.3.29c.

Way of rendering images on a CRT monitor is based on the elimination of an electron beam from the electron gun using electromagnetic system, so that the image is drawn line by line from top to bottom of the monitor. The more line height (vertical resolution) and as many picture elements in one line (horizontal resolution) of the displayed image is superior. When the electron beam redraws an image back to the beginning and the procedure is repeated (raster scan). Removal of the jet made electronic circuits monitor based on the contents ANALOG signal obtained from a computer graphic system. The analog signal controls the amount of electrons in the jet that 'firing' triode, color by color, and the intensity of illumination of the triode is greater when the amount of electrons in the jets greater. It is also called RGBY signal, whereby the ' Y ' refers to the brightness of your monitor image especially for black and white pictures, and not the yellow color (Yellow), which are used as a fourth color some technological solutions. When they return to start drawing a new line or image stream of electrons temporarily 'off' (reverse jet). To the human eye would not have noticed the difference when you change the image, it draws 50-150 times per second (refresh image - vertical frequency), based on which it can calculate how many pixels per second can be displayed in one line (horizontal frequency, 30-100 kHz).

If the monitor can operate at higher frequencies, which means that his persistence (time displaying one image) small and in one second it can display multiple images as well due to less eye fatigue, it is possible to better reproduce quickly change between different 'frames' which is important avid gamers. So a 19" CRT monitor SyncMaster 997MB has the size triodes of 0:20 mm, maximum image resolution and accompanying is refresh - 1920x1440@64 Hz and recommended resolutions and refresh images - 1280x1024@85 Hz. For general culture; PAL TV signal draws 576 lines 50 times a second on the way to one picture is repeated two times (displays 25 images) and so that she displayed in the first remedy 'odd' features images and other 'odd' and seq. Each line contains data from approximately 768 picture elements. It is intertwined (interlaced) mode that computer monitors are no longer used. Such signals may provide a separate graphics card connector (S-video) to display images on a TV set.

Described view based on the monitoring of individual pixels is called raster (bitmap) image. Another way is to display vector images composed of geometric shapes drawn, that the image is defined by mathematical formulas which allows its two-dimensional (2D) and three-dimensional (3D) visualization, but the objects are watching the display image on the screen converted to raster. But vector images drawn on the example of the 'Corel' program to support its high-quality, zoom in or out without 'distortion'. Where appropriate files are easily transferred to another format. Today's games use vector graphics card content from scene to scene turns into a raster image and 'sends' monitor. Direct vector display on the monitor control of movements of an electron beam across the screen to draw the objects used by the mid-80', and about just as much.

Under the principle of color mixing work and LCD (Liquid Crystal Display) monitors. LCD color monitor for leakage management uses back light with filters for each primary color in each picture element. Consumption of these monitors is very small. As a matrix triode which are controlled by electronic circuitry responsible for monitoring the vertical and horizontal position of the triode, which needs to be 'light' concept of removing the jet does not exist. Complete the grid can be set to display 'at once'. With a refresh rate of the monitor type is defined and the response time, the time required to change the display status triode with 'black' to 'white' and vice versa. Acceptable value is a maximum of 12 ms, corresponding to a frequency of 75 Hz refresh rate.

LCD monitor consists of two polarizing filters whose lines are perpendicular. Filter between the molecules of crystals that have an ability to swivel if the potential exists between the filters. Filters pass only light rays that are parallel to its lines. The light source is located behind the first filter through which the only rays that are 'parallel' with grid filter and missed all the beams have the same polarization. Liquid crystal layer between the filter is set so that the molecules in the absence of the potential difference between the plates of the filter there is a ray of light polarization rotation of 90 and smooth beam of light passing through the second filter. With the presence of the potential difference between the plates of the filter is too complex crystal molecules so that there is no rotation of light rays by 90 and the beam of light can not pass through the second polarizing filter. Resizing the control voltage, rotate the molecule and is dependent on the amount of control voltage changes their rotation, and the amount of light that can pass through the second filter. In this way controls the brightness level of the screen image. LCD is always made so as to be adapted to work in a specific definition applied to a balanced number of liquid crystals, for example, a 15" LCD screen will be adapted to the resolution of 1024x768 pixels, and it is working native-resolution LCD monitor, one triode - one pixel.

Cheaper variants of light source is a gas 'pipe' that gives light polarized along the wallpaper full screen or used quality LED lighting for the entire screen or to turn individual 'LED bulbs' care to serve one pixel. Uniformity of brightness across the entire screen background is an important factor in the quality of the display. LED lighting is largely resolved anomalies gas lighting but expensive solution. Particular attention should be paid to the intensity of the back light. No use of the monitor if the back light is so strong that they lose all the nuances in the colors of the image, especially if you can not adjust the brightness. For professional work setting of color screen display monitor is of great importance.

Monitoring potential differences between individual fields filter performed transistors, TFT (Thin Film Transistor) technology shall arrange layers of lines and transistors on the glass, forming a two-dimensional matrix in a similar way as in RAM (Figure 3.5.13). On one axis of the matrix comes across a group of guides which leads analog picture signal (data input) that controls the angle of rotation of molecules, and the other axis of the matrix are the guides for the control signal (gate scan) that determines which transistor in the row matrix allows management. Each picture element (triode) transistors, which has its own group to monitor liquid crystals, so that in a single pixel needs three. With each transistor is embedded capacitor to hold the potential for a time as the image would flicker and before the 12 ms. Pixels are organized as a series of stripes blue, then red, then green, and blue again (in rows like Trinitron CRT), and the color gets so missed the light passes through the blue, red or green filter. Color filters are nothing more than yet another film in paint over the polarization filter. As light passes through the two grids, rather focused and these monitors have a limited visual angle viewing range. Depending on the angle of view to a greater or lesser extent, the color of the display which should also be taken into account when purchasing monitors. IPS (In-Plane Switching), PLS (Plane Line Switching) or ASV (Advanced Super View) technology in relation to the TFT technology produces better results, but are more expensive. Regardless of all the above LCD monitor can never provide image quality as CRT monitor, especially the experience of black color, and the color range is typically 16.7M colors (24 bits), and the only advantage is much smaller dimensions and power consumption.

CRT at its conception occupies a large volume, and must have a source of over 10'000 V anode voltage. Attempts to reduce the 'depth' CRT's never led to some acceptable results. The first successful concept to reduced volumes and lower operating voltages PDP (Plasma Display Panel) monitor . Plasma monitor uses the principle of bombing and excitation phosphor display elements with ultraviolet (UV) radiation from ionized 'bubbles' of gas. The light at the same time creates a proportional to the intensity of the UV radiation, which is proportional to the difference of potential between the excitation electrodes. An example of how this process takes place in an environment of electrodes shown in the next picture.

Each element of color image consists of a single bubble, placed very close to the glass screen, so compared to the CRT waste deflection of the electron beam, the large thickness monitor and a large voltage. In the space between two glass substrates is xenon or neon gas at low pressure. Under normal circumstances, this gas is made up of a set of particles with no charge that atoms that have the same number of protons (positively charged particles) and electrons - plasma. Electrical potential between the excitation electrodes causes the ionization of gas in the neighboring environment around the electrode in the form of 'bubble'. When excited, the particles collide with each other. These collisions excite the gas atoms in the plasma and in so doing releases the light.

 Plasma monitor - cell
Figure* 3.3.34 Principle of the plasma monitor. ( + / - )

Potency excitation electrode itself is not enough if they do not thereby 'helping' address potential electrodes. If you look at the spatial organization of the screen to Figure 3.3.34b, it can be concluded that the bubble would occur only in places where such electrodes 'crisis'. So, to be controlled by UV radiation in a small area at exactly defined location. If an address electrodes 'R' or 'A' or 'B' to a potential, the bubble will occur only between the electrodes '1-1' if the difference between them has potential but not between electrodes '2-2' if they were potential differences no. Address electrode and excitation electrodes forming a matrix is the potential managed electronic circuit that based on the received image signal to decide where it will cause ionization and where not.

UV radiation is directed to the ground and emitting phosphorus coating the screen which must therefore be transparent to visible light. To blistering better localization of phosphor colors are separated by insulating barrier (separator) and resembles the structure of the phosphor CRT with TRINITRON principles of operation. To localization bladder as much improved and there is that within the concept of making a coating color has transverse separators between the electrodes '1-1' and '2-2', for example, so that a complete phosphor resembles the set of complex micro box so resemble the great backing paper for storing eggs or honeycomb.

The technology is very expensive and is suitable for large size monitors and therefore the PC still prefer to use LCD monitors or new upcoming technology of which is described on the following page. Common to CRT and plasma technology is a feature of both excitation using phosphoric elements in different colors and that they do not need a back light for LCD technology. Watching the images shown from the angle they were good. One might even say that a bunch of small PLASMA CRT devices. Titled 'neoplasm', more modern generation of the screen is used to separate compartments for each subpixel (honeycomb), and for each of its sub elements (RGB), has reduced the intensity of UV discharge, shorter response luminous phosphor elements which allows greater dynamic images that are displayed , transparent screen material with electrodes and anti-reflective coating on it, which eliminates the reflection of external light, which significantly contributes to the brightness and contrast of the displayed images and a more realistic understanding of black.

If the monitor screen matrix with embedded touch sensors, it is possible to create a program that will support in accordance with the button in the screen to make some sort of action. This technology using specific types of cell phones and similar devices. The technology is very useful for systems that have a dedicated programming support to manage some of the production process, or other similar action. For computers generally dedicate whose content is constantly changing screens above and does make some sense. Nevertheless, it was nice to see members of the government to wisely pressed pencil boxes on the screen to get the content that they probably prepared by a group of developers as it would effectively ruled. So, the screen is a computer input device that operates in accordance with the on-screen display.

 LED dioda It has already been quite a while since I have been in commercial use of light emitting diodes (LED - Light Emitting Diode) light emitting different colors, and that it might not even realize it. Towards the end of the last millennium were popular wrist watches that showed the time and date as alphanumeric characters (no hands), but the batteries as a source of power diodes relatively quickly consumed. So she looked at the clock by pressing the button, which included a circuit to power the diode and hence the time display for a few seconds. Since then it has much has changed.

Organic LED - Organic Light Emitting Diode technology is based the fact that in the field of controlled matrix of electrodes that are driving the LED elements - organic light emitting layers, which are stacked in triode along similar principles as CRT and LED devices. So, it's a technology that does not require back light. Energy consumption is small, and the intensity of the light generated by all the closer the characteristics that have LCD and plasma and fully comply with installation in mobile or portable MP3 players and other small electronic devices. Making for them is pretty simple, but for monitors this technology is still too expensive. On glass or a transparent plastic substrate, as shown in Figure 3.3.32a anode electrodes are placed in HIL (Hole Injection Layer) layer, which is placed on the organic layer, depending on the composition of the light emitted by different colors (RGB in this case). The organic layer is applied to the ETL (Electron Transporting Layer) at the cathode. When between the anode and the cathode voltage source connected and regulated current through the diode fails, the result is a broadcast light.

 OLED monitor - triode
Figure*** 3.3.32 Principle of OLED monitor. ( + / - )

As transistor elements are monitored each diode in the matrix shown in Figure 3.3.32b best (active matrix). Control electrodes analog signal controls the flow of current through the diode to the connection scheme that resembles the Figure 3.5.13 plus diode in parallel with a capacitor. Thus, each RGB triode and its every component 'R', 'G' or 'B' element are addressed network (matrix) lines and electrodes that monitor electronic circuits. Electronic circuits based on the received image signals determine what and how a single triode and its elements should work. In a similar way it works and matrix LCD monitor. These analog signals can not be confused with the signal which is a digital image from which the 'development' need of an analog signal to control the brightness of the triode.

It is possible to achieve control with LED direct change in voltage between the anode and the cathode (passive matrix) but the control electronics complex. The response time diode is very small (order of ms) that along with daily improvements in terms of the amount of light generated guarantees all the mass use of these monitors in the future. Besides layers of materials that allow you to bend the plastic screen surface may not be completely flat. Since the entire system fails to light, it simplifies the process for reducing the flash from the outside world as the previous monitors of any kind is not the case. As the substrate is transparent, and behind it you can set the background that has the property of good absorption of light and the quality of the 'black' views are very good, and the influence of ambient light on the display alone is much lower than the previously mentioned technologies. OLED technology is still expensive, but if nothing else, the user is watching himself on screen :-). In Figure 3.3.32c shows a very practical use of the keyboard, and all modern clocks use it as shown in Figure 3.3.32d. Only a matter of time before the technology is even more enhanced and implemented in TV sets and computer monitors. Have already produce the UHD (Ultra High Definition) monitors and TV sets, resolution of over 4000 pixels, that can provide a far greater range of colors (Gamut) of RGB and LCD monitors.

Regarding demands for display HD1080 content, no matter what type of monitor is used, it is advisable to have a screen resolution of 19201080. If you are using monitors that have lower resolution than the specified picture quality depends on the quality of the logic of the image SCALING to smaller resolutions. Monitors physically smaller size for the same native resolution have higher DPI, which enables high-quality viewing images at a small distance from the monitor. Watching the images on a large monitor at close range does not make for a good atmosphere around because the perception of understanding the image pixels can not 'merge' and looks 'grainy'. HDTV multimedia content displayed on the UHD devices will surely provide a much better feeling to user compared to display on devices with a standard HDTV resolution, regardless of the physical size of the device.

 Back
 Search
 Next

 Content - Home
 Content  Informatics Alphabet
 
Citing this page:
Radic, Drago. " IT - Informatics Alphabet " Split-Croatia.
{Date of access}. <http://www.informatics.buzdo.com/>.
Copyright © by Drago Radic. All rights reserved. | Disclaimer