Monitor LCD


A monitor LCD

flat was, until recently, the wet dream of all PC enthusiasts . Within a few years, however, the dream has become reality. Today, most PCs are equipped with monitors of this type and the old cathode ray tubes seem destined to a rapid oblivion . The changing of the guard is not the case for the problems of image quality , as a tube monitor is absolutely worthy of a good LCD (indeed , it is often even better ), but for a long series of reasons.

First of all, the small footprint , especially in depth ( with the continuous increase in the size of the screen ( now part is 17 ” ) , which is necessary for the dozens of open windows on the desktop , manufacturers have found to use cathode ray tubes deep over 40 cm , hard-to- place for those who have large desks . advantage of the LCD in this case is unassailable : the point of greatest thickness is the support base – unless you choose to mount the display on a stand (VESA video Electronics Standards Association ) from the wall or swing arm – and the increase is minimal as the size of the screen. the second advantage of LCDs is the absence of ionizing radiation. ‘s common knowledge that the cathode ray tubes emit high-energy radiation and the user will never feel entirely comfortable , as the levels are minimal , the waves are imperceptible to more than five inches from the surface of the screen and the monitor are manufactured according to the standards TCO and MPR II ( which provide stringent limits ) . With LCDs there is no radiation , since the image is not formed using a brush of accelerated electrons , and the problem is solved at source. Last but not insignificant advantage of LCDs is that their energy consumption is much lower than that of a cathode ray tube of comparable size. If in the case of a single monitor is not much difference , things change if we consider large organizations or even entire countries.

 

The energy savings derived from the use of LCD monitor in place of the conventional tube is so high that states like California ( where the problem of energy consumption is strongly felt ) had arrived to provide tax incentives for the adoption of this technology. In the face of these undeniable advantages , LCDs have not been favorites for a long time for two reasons: the high price and the image quality is not particularly convincing. The issue price , as you can see from its entry in our board , it seems now in the process of solution monitors the dishes we tried costing roughly how much you paid for a couple of years ago for a tube monitors . The decline is due in part to the improvement of production technologies , which have allowed us to drastically reduce production waste ( initially very high ) , and to a greater extent to entry of new producers of LCD panels , a key component of the flat panel monitor. The result was a sudden overproduction that led to the rapid drop in prices .

Fast and powerful HD video editing, including 3DObviously, a lower cost increases demand , which in turn makes up the price here is explained the curious swing of the lists of the LCD, which in some periods ( for example, the pre-Christmas ) dart at the top and then resume the descent when demand slows down. The producers have also worked a lot on the second problem , the one on the picture quality. The first step has been the widespread adoption of the technology known as TFT (Thin Film Transistor) or ” active matrix ” , instead of the cheapest but lackluster passive matrix screens . In active-matrix LCD , each point on the screen is controlled directly by a transistor , allowing you to have a switching point off / on more quickly and effectively.

Obviously, producing a panel active matrix , where they must find a place more than a million transistors , is considerably more difficult , but the result more than offsets the greater complexity of the production. After the adoption of the TFT technology , it has gone to work on the physical characteristics of the panels ( shape and arrangement of pixels and color filters, color characteristics , the composition of the “sandwich” – the various layers that make up the panel – and so on ) finally, we worked to improve the backlight systems , typically based on cold cathode fluorescent lamps (Cold cathode Tube) .

The practical result of these refinements is that today’s LCD monitors have a picture quality that , as appropriate , ranging from good to excellent , with a remarkable level of detail ( images appear very “net” ) and a reproduction of the color generally acceptable. In addition, current monitors have very good values ​​of lateral and vertical visibility . The image is clearly visible and retains its color content also looking at it from the side or from above. Thanks to TFT technology , even the response time of the pixels have been sped up , and now no LCD monitor on the market exhibits annoying ” contrails ” whenever an object moves on screen. However, there are different speed classes and only used monitor ” fast ” are suitable for extreme uses such as games, for example.

Unresolved issues Against these advantages , the LCD exhibits some problems still not resolved, or in the process of resolution. The first is the resolution that due to the nature of the LCD monitor is fixed: in practice, a monitor to 1,280 x 1,024 points will display correctly only screens to 1,280 x 1,024 points , while showing lower or higher resolutions will have to resort to ‘ interpolation , usually with poor results . For lower resolutions , you often get better results by viewing the pixels in a 1:1 ratio , using only a portion of the screen. Another problem is that of the so-called ” color temperature “, ie the calibration of the hue of the color emitted by the monitor.

While in traditional tube monitor is always possible to change this setting , only the more sophisticated LCD monitor are equipped with a similar control that acts on the shade of the light emitted from the lamp that illuminates the rear of the panel . In all other cases, you should use a color profile on the PC, allowing the graphics card to the monitor image already correct . Fortunately, this problem affects only those who work in areas such as digital photography or graphics , where it is important to have a perfect match between what you see on your monitor and then what will be printed . Third and most difficult problem is that of the so-called “dead pixel” , or dead pixels . The problem stems from the fact that the technology of production of the panels is very similar to that of the chip and just a very small impurities or imprecision to meet up with one or more pixels that are always dark or always lit . According to the producers , a number of defective pixels is physiological but those who buy the monitor , obviously paying with euro ” not bad” , sees things differently and expect a perfect product.

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The result was a long series of diatribes about replacing or less of monitors considered “acceptable” by the producers and “bad” by users. A year ago, the situation has improved somewhat since entered into force on the ISO 13406-2 standard that determines precisely the imperfections of a monitor with respect to the class. Unfortunately, today, every manufacturer has decided to interpret differently the information provided by the standard, for which the critical situation persists .

The good news , in this case , is that the production technologies are improving rapidly and , for example, none of the monitors tested exhibited defective pixels, while in a similar comparison carried out one year ago almost all had one or more display pixels burned

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