by Oleg Artamonov
08/29/2008 | 01:34 PM
A few years ago, in 2003 or about that time, many analysts were predicting a bright future for LCD panels manufactured using MVA and PVA technologies (both have similar characteristics and are often referred to jointly as just VA). Such panels seemed to be a reasonable compromise between expensive S-IPS on one hand and TN+Film, which had neither high image quality nor low response time, on the other hand. Thus, TN matrixes were expected to populate the bottom market sector, S-IPS the top sector, and VA would take the golden mean.
Unfortunately, this prediction never came true. The crucial moment was the introduction of “fast” TN matrixes with a specified response time of 16 milliseconds. Yes, we know today that those 16 milliseconds were only achieved on the transition from pure black to pure white whereas on halftone transitions a regular TN matrix of that time could be as slow as 40 milliseconds. VA matrixes were hardly faster then, though. Having a specified response time of 25 milliseconds (on the black-white-black transition), they could be as slow as 100 milliseconds and more on transitions between dark halftones.
Thus, TN technology had got two trumps: low price and a pretty number in the specs. And it is the response time parameter that most customers base their choice of the monitor on. VA technology began to retreat.
The market superiority of TN matrixes developed over the following years. Their response time decreased to 12 and then to 8 milliseconds. Although these numbers had little to do with reality (because the matrix could only show such a high speed when displaying a black-and-white picture without any halftones), they did affect the customer’s buying decision.
And then response time compensation technology (it may also called response time acceleration, Overdrive, and some other names by particular vendors) came to solve the problem of high response time on halftone transitions. As a result, RTC-enabled VA matrixes acquired a response time of below 15 milliseconds while TN matrixes, 4 and then 2 milliseconds. What is important, in both cases it is the real response time, measured according to the new method as the average of all the transitions between all possible halftones (this method is referred to as Gray-to-Gray or GtG) as opposed to the old method that measured the black-white-black transition only (referred to as Black-to-White, BtW or ISO 13406-2 according to the name of the standard that describes it).
RTC-enabled monitors with every matrix type had become universal in terms of home-multimedia applications. VA-based monitors now could be used for anything, including games. Did this help them regain their market share? No. VA matrixes had become faster but TN were faster still: 2-4 milliseconds (GtG) of TN matrixes as opposed to 6-8 milliseconds (GtG) of VA matrixes. For many customers these numbers were quite definitive. Not all users knew what these milliseconds actually meant and were needed for. Moreover, TN remained cheaper as before.
As a consequence, we can now see a total invasion of TN-based monitors that are ousting every other manufacturing technology. In the 19-inch sector you can only find the slow SyncMaster 943T from Samsung (a 25 milliseconds PVA matrix without RTC) and the expensive semiprofessional 1990SXi from NEC (an S-IPS matrix). Among 20-inch and 21-inch monitors nearly every popular model based on an S-IPS or VA matrix (Dell’s 2007FP and 2007WFP, Samsung’s SyncMaster 215TW, Philips’s 200P7ES and 200WP7ES) is now out of production and off the shop shelves. 22-inchers were introduced with TN matrixes originally. As for 24-inch monitors, most of the new products announced throughout the latest months are based on TN (Samsung’s SyncMaster 2493HM and T240, BenQ’s G2400W, NEC’s AccuSync LCD24WMCX, etc). Even huge 26.5-inch monitors now use TN technology. I guess the 30-inch diagonal is the only one left which is totally free from TN. Every 30-incher is based on either VA or S-IPS so far, but I’m afraid this will change soon, too.
Well, I don’t mean that there are no VA- or S-IPS-based monitors with a diagonal below 24 inches at all. There are just no mainstream models with moderate prices. Professional solutions such as NEC’s MultiSync LCD2090UXi or Samsung’s SyncMaster XL20 will be available for long but their pricing is sure to repel a large share of customers. These monitors are intended for people who need precise color reproduction, wide setup opportunities and nonstandard characteristics. They were expensive and will always be expensive. It wouldn’t be wise to buy such a monitor unless you are sure you really need this specific model with all of its special features.
So, are TN matrixes so bad after all? Well, no. For example, I’m writing this report using a TN matrix. But they do have a number of definite drawbacks, the most annoying of which concerns the viewing angles. Although TN technology has progressed over the recent years, it is still uncomfortable to watch a movie on such a matrix while lying on a sofa. The image gets dark when viewed from below, its top part differing from the bottom in brightness. The brightness and color reproduction of a TN matrix change as soon as you move your head relative to the screen. These changes are quite visible to the eye. Again, the bottom of a TN matrix gets bright when viewed from above. When viewed from below, the top of the matrix gets dark.
The monitor manufacturers had even invented a new method of measuring the viewing angles especially for TN matrixes in order to frighten the customer less. They began to measure the angles for a contrast ratio reduction to 5:1 rather than 10:1 as with VA and S-IPS matrixes. As a result, the specified viewing angles of TN matrixes grew from 130-140 degrees to 160 degrees – only on paper, of course. Moreover, even those 140 degrees (70 degrees into either side from the normal to the screen) were the angle at which the picture already stood no criticism rather than the angle at which you noticed any changes in it.
The manufacturers are now trying to return to the single method of measuring the viewing angles. Samsung’s latest series of TN-based monitors are declared to have viewing angles of 160 degrees according to the 10:1 method. But since the use of the relaxed method was never advertised (at the best it was mentioned with small print in a footer), the marketing effect from returning to the single measurement method can hardly be big.
As for VA and S-IPS matrixes, their viewing angles (measured according to the contrast ratio reduction to 10:1) have long become 178 degrees. In other words, the angles are limited by the screen bezel. In practice, you can spot a certain reduction of the contrast ratio on an S-IPS matrix without any changes in color reproduction when you deflect your head from the center of the screen. With a VA matrix you can see a bigger reduction of the contrast ratio and an additional tonal shift, yet these effects are far less conspicuous than with a TN matrix.
So, TN matrixes have conquered the market due to marketing rather than technical reasons. They are cheap and have a very good specified response time. Looking at the pretty number of 2 milliseconds printed large on the box and then at the pretty number on the price tag, the customer makes up his decision easily and buys a TN-based monitor. The more expensive VA and S-IPS matrixes enjoy lower demand now. It is unprofitable to make them, so they are leaving the production lines. Manufacturing professional monitors remains a rather stable business but their price is often unaffordable for people who might be interested in mainstream VA and S-IPS monitors. C’est la vie.
But what can we do if we are not satisfied with the characteristics of TN-based monitors and cannot afford one of the still available large VA-based monitors? Should we wait for new technologies such as OLED or FED that can hardly become mainstream until the next decade and will hardly be affordable even then?
Fortunately, Lenovo and Samsung have taken care about us. I mentioned above that 22-inch monitors were originally introduced with TN matrixes. No other matrix type was available for this diagonal. However, Samsung has recently released a 22-inch S-PVA matrix (LTM220CS01) while Lenovo has introduced a monitor based on that matrix. The monitor is called ThinkVision L220x.
I should also note that EIZO offers a 22-inch S-PVA monitor as well. It is the S2231WSE model but we haven’t yet had a chance to test it.
Lenovo took the PC, notebook and monitor manufacture over from IBM. The latter had preferred a stern, laconic style and black color.
Lenovo stays true to those design principles. The ThinkVision L220x has a single-color dark-gray case. A wavy row of buttons is the only embellishment here.
The monitor is rather massive. It seems small from the front due to the thin screen bezel but its case is quite thick.
The monitor’s native stand uses standard VESA fasteners, so you can easily replace it with a VESA-compatible mount, for example if you want to hang the monitor on a wall.
The stand allows to adjust the height of the screen (from 70 to 180 millimeters counting from the desk to the bottom edge of the screen), tilt it or pivot it into portrait mode. The screen can also be turned around the vertical axis – the base of the stand remains motionless at that.
The stand is locked in the bottommost position for easier transportation by means of a plastic bracket (it is already removed in each photograph).
It is handy that the base of the monitor is motionless when you rotate the screen around – thanks to the hinge in the pole of the stand. Many other models have a rotating circle in the sole of the stand and their stand is rotating together with the screen as a single whole.
The power and video cables can be placed into the immovable part of the stand under a cap.
The ThinkVision L220x has the following connectors: a digital DVI-D, analog D-Sub, and an integrated 4-port USB hub. To the left of the connectors there is a cable holder. The power adapter is integrated into the case.
Two of the USB hub’s ports are located on the bottom edge of the back part of the case and are meant for permanently attached devices such as mouse and keyboard. Two more can be found on the side panel – they are handy for flash drives, etc.
The monitor’s controls are placed in the bottom right of the front panel in a kind of a wave. They are labeled in paint. Additional markings are painted in different colors. All of them are easily readable under normal lighting. Quick access (without entering the main menu) is provided to switching between the inputs, to the auto-adjustment feature, and to the brightness setting. The buttons respond softly and neatly to your fingers.
The Power indicator is located to the right of the corresponding button. It is small, not very bright, and green. It is not distracting at work. The indicator changes its color into yellow in sleep mode.
The exterior design of the ThinkVision L220x is okay. It is a neat and handy monitor. I guess the only feature missing in it is the ability to quickly switch between different levels of screen brightness. The monitor just doesn’t offer such factory-set image modes, perhaps due to its overall office-oriented design. Such modes are useful at home so that you could quickly adjust your monitor for a particular application (office applications, movies, games, etc) but virtually unnecessary for office work.
Onscreen menus of different LCD monitors only differ in terms of interface design and some minor nuances. All of them offer the same standard selection of setup options. That’s why we don’t usually discuss the onscreen menu at length in our reviews but only remark on the drawbacks and untypical settings available in it. But this review is entirely dedicated to one monitor, so I would like to discuss its setup options and give you some tips on how to use them.
The menu of the ThinkVision L220x consists of five sections whose icons are placed in a row at the top of the window (the sixth icon is for exiting the menu; it is redundant as you can quit the menu by pressing the Cancel button repeatedly).
Inside each section there are icons and text explaining the meaning of the icons. The text appears when you select an appropriate icon.
The first menu section contains brightness and contrast settings. Selecting an icon and pressing OK, you get a slider with a scale from 0 to 100. Note that the brightness of the screen changes the same moment you change the position of the slider. But if you press the Cancel button, the settings will be reset to their previous values. To save your changes, you must exit each menu section by pressing the OK button. The L220x differs here from most other monitors in which every setting is applied and saved just as you change it rather than when you press a certain button.
Like with nearly every other LCD monitor, the Brightness option means the regulation of the brightness of the backlight lamps. The Contrast option means the regulation of the maximum transparency of the LCD matrix (in other words, it is the regulation of the brightness of white without changing the level of black). That’s why you should try to achieve the necessary brightness of the screen by means of the Brightness setting. If the screen is too bright even at the zero level of this setting, you should use the Contrast setting then. Why? Because the backlight lamps affect neither color reproduction nor contrast ratio whereas the Contrast setting reduces the effective contrast ratio and the available dynamic range (you’ll have the same problems if you are adjusting the image with the graphics card driver, by the way).
I don’t mean you shouldn’t touch the Contrast setting at all. The monitor must be set up in such a way as to strain your eyes less. Both a very high and a very low level of white are no good for your eyes.
It is quite easy to select the necessary settings. Place a sheet of white paper next to the monitor and set the latter up (using the Brightness setting first and then, if not enough, Contrast) so that white on the screen was about as bright as the paper. Of course, the ambient lighting must be good. This is the natural requirement every doctor will tell you about irrespective of the monitor model. It is not good for the eyes if there is a high contrast between the screen and its surroundings.
The next two menu items are needed to set the image up at analog connection. They are unavailable at DVI connection, and I wouldn’t recommend you to connect a 1920x1200 monitor to your graphics card’s analog output.
So, you have set the monitor’s Brightness and Contrast up in such a way that its white is the same brightness as the sheet of paper. It differs in color, though. The monitor’s white is obviously bluish. It means you have to tweak the color temperature settings.
They are divided into two groups in the monitor’s menu: preset modes and manual adjustment.
There are four preset modes: Reddish, Bluish, Neutral (in between the previous two) and sRGB. The latter mode is called after the sRGB standard that describes typical monitor characteristics, namely a gamma of 2.2, a color temperature of 6500K, and 80nit brightness. The sRGB standard declares certain brightness, so when you choose this mode, the manual Brightness and Contrast settings are locked like in many other monitors. You’ll see shortly how close the sRGB mode settings are to the sRGB standard.
If you don’t like any of the preset modes, you have to use the manual adjustment.
Unfortunately, color temperature is set up by balancing three colors (red, green and blue) rather than by means of a single slider (in degrees Kelvin). In fact, green might be calculated automatically. Its level depends on the ratio of red to blue. If this correlation is broken, the screen will be either pink (lack of green) or greenish. However, the manufacturers don’t find time to introduce the appropriate algorithm into the onscreen menu.
The manual adjustment with the three parameters requires patience or a hardware calibrator (such as our DataColor Spyder 3). I will give you a few tips about that shortly.
When you choose the desired values for all the three colors, select the Save item and press the OK button. Otherwise your values will be reset to the previous ones when you quit the menu.
The last menu item contains settings that refer to the menu proper. You can choose the language, position of the menu on the screen, and the time-out for the menu to disappear automatically. You can also view the monitor’s current resolution or reset all its settings to the factory defaults.
Use the following link for a description of our testing methodology, the equipment we use, and a brief explanation of what the specified and tested parameters of LCD monitors mean: X-bit Labs Presents: LCD Monitors Testing Methodology In Depth. If you feel overwhelmed with the numbers and terms this article abounds in, check out an appropriate section of the mentioned article for an explanation.
Our methods have changed somewhat since the earlier reviews. We now use a Spyder 3 Elite calibrator instead of a Spyder Pro. The newer calibrator is more accurate at measuring the level of black. The contrast ratio results in our tests have increased as the consequence due to the increased measurement accuracy.
The L220x is interesting not only due to its matrix type but also due to the non-typical resolution (for a 22-inch model). Its native resolution is 1920x1200 pixels. You don’t need a special graphics card or even a dual-link DVI output to support this resolution. Every modern graphics card, including notebooks’ cards, supports it via DVI. Of course, DVI is desirable because analog connection does not always yield a sharp image.
That’s why I was greatly surprised to see such a low-sharpness image on the screen of the ThinkVision L220x that it was virtually impossible to work with text. The connection was digital. This didn’t resemble the classic blur like at analog connection or when working at a non-native resolution. There was a gray shadow, one pixel wide, to the left of each black vertical line, including fonts.
Realizing I was dealing with a defective sample, I exchanged it for another. Both samples of the L220x had firmware M10, but the first was dated March 2008 and the second, February 2008.
The second monitor was much better, yet not ideally sharp, either.
As you can see, there is a one-pixel shadow above horizontal black lines now. I could work more or less normally at this monitor so I didn’t exchange it for another sample. However, the fuzziness is not altogether inconspicuous.
For comparison, and to prove that the shadow is not a defect of the snapshot, I can show a snapshot of a SyncMaster T220P, another 22-inch monitor with a resolution of 1920x1200 pixels but with a TN matrix.
Samsung SyncMaster T220P
As you see, the sharpness is ideal. There are no shadows here. While the defect of the L220x is not eye-catching, you notice it as soon as you compare the L220x with the T220P or any other monitor.
So, it seems like some samples of the ThinkVision L220x have an inherent defect. They yield a low-sharpness picture even when connected via DVI and working at the native resolution. This defect can vary from barely visible to very strong, and I cannot explain it. The two samples I dealt with differed in the manufacture date, and the newer sample was far worse than the older one.
I can only give you this piece of advice: when purchasing a ThinkVision L220x you must check out its image sharpness at DVI connection and 1920x1200 resolution. If the image is not sharp enough, refuse to buy the given sample because this defect cannot be corrected by any settings.
As for the increased native resolution (1920x1200 instead of the traditional 1680x1050), it means that the L220x has a small pixel pitch. As a result, icons, fonts and other interface elements of the OS and applications are going to look smaller (you can try to scale them up, but not all applications support such scaling). So, if fonts seem too small to you on 17-inch (1280x1024) and 20-inch (1680x1050) monitors, the ThinkVision L200x will hardly suit you. But if you prefer a smaller pixel pitch, from the notebook’s 12-inch (1280x800) to huge 30-inch panels (2560x1600), the L220x will be okay. Its small pixel pitch ensures more accurate, detailed rendition of images, smooth lines of fonts, and superb display of photographs (without the unnaturally increased sharpness typical of large-pixel monitors). In other words, this is a matter of your personal taste and visual acuity but you must consider this issue before purchasing the L220x due to its nonstandard resolution. I personally had no problems with the L220x’s native resolution despite my poor eyesight and spectacles.
The monitor has 80% brightness and 85% contrast by default. I achieved a 100nit level of white by selecting 30% brightness and 34% contrast. To remind you, the 100nit white is a reference point in our tests. This brightness is appropriate for working under good lighting at the office. When achieving it we try to reduce the brightness and contrast settings in the same measure in order to see if there appear any problems with color reproduction. If you want to know how to set the monitor up for your personal workplace, I’ve given my advice in the previous section.
The monitor regulates its brightness by means of backlight modulation at a frequency of 212Hz.
You should not increase the Contrast setting above 85% as it makes light halftones indistinguishable from white. The Brightness setting can be increased up to 100% without any problems.
Color gradients are reproduced perfectly at the default settings but barely visible banding can be seen at some other values of contrast. This is not a big problem, though.
According to my measurements, the monitor’s maximum brightness is about 360 nits, which is more than enough for movies and games even under bright daylight. The contrast ratio is as high as 800:1, which is a superb result, too.
I expected the sRGB color temperature mode to yield the parameters described by the sRGB standard but it did not. The standard describes a brightness of 80 nits whereas this mode is four times as bright as that. You can’t work at the monitor at such settings. Even playing a game is going to be uncomfortable unless under bright daylight. It is not clear why the manufacturer implemented a separate mode with such odd settings.
The last column in the table is Custom, i.e. user-defined settings. They differ from the monitor’s default settings and were selected by me manually – I’ll tell you about them shortly when I’ll be discussing the color temperature measurements.
The ThinkVision L220x features an extended color gamut thanks to backlight lamps with improved phosphors. As the diagrams suggests, its color gamut matches the standard sRGB color space ordinary monitors more or less comply with, in reds and blues but is much larger in greens.
There is in fact one benefit from the extended color gamut. The L220x can display a very pure, saturated green whereas sRGB monitors produce green with a tincture of yellow. There are two drawbacks, though. First, photographs intended for sRGB monitors will have a shift of some halftones towards green (I wrote about this effect in an earlier article) unless you apply special correction. Second, the diagram shows that the point of green is shifted leftward rather than upward. As a result, the L220x offers a wider range of turquoise hues but cannot display some yellow hues.
To correct the mentioned problems at least partially, you should install a monitor’s ICC profile into your system and specify it in your image-editing software. You can download the profile I obtained with a DataColor Spyder 3 Elite calibrator here.
As for the sRGB mode in the color temperature screen of the monitor’s menu, it has no effect on the color gamut and does not bring the latter to the standard sRGB space.
The gamma curves are close to each other at the default settings but differ from the theoretical curve for gamma 2.2 which goes lower (it is black in the diagram). >From a practical point of view, it means that the L220x displays halftones lighter than they should be. This drawback can be corrected by calibration with a special tool or by increasing the gamma in the graphics card driver. The L220x itself doesn’t offer a gamma adjustment option.
The gamma curves do not change much at the reduced brightness and contrast. They are still higher than the theoretical curve. More importantly, the monitor is able to reproduce the entire range of halftones, without losing in darks or lights.
Now that I have begun to scrutinize the sRGB mode, I want to show you its gamma curves, too. Although the sRGB standard specifies a gamma of 2.2, the diagram shows the same discrepancy: the gamma curves of the L220x are higher than the theoretical one. In other words, the gamma value is lower than 2.2
The ThinkVision L220x is set up well in terms of color temperature. The difference between the levels of gray is small in everywhere except for the cold Bluish mode. And if you reduce the contrast setting from the default 85% to at least 75%, the difference in the Bluish mode gets small, too.
On the other hand, the absolute temperature values are high. The Reddish mode yields a color temperature of about 8000K and is going to look bluish rather than reddish. The sRGB isn’t any warmer although it should yield a color temperature of 6500K according to the sRGB standard.
Trying to achieve a warmer image from this monitor I reduced its contrast setting to 75%, set the color temperature mode at Custom and chose the following: Red=100, Green=89, Blue=87. The result is shown in the last column of the table. As you can see, it is close to the desired 6500K. So, if the L220x seems to produce an exceedingly cold picture, try to set it up like I did.
The table with the results of my brightness and contrast ratio measurements also had a Custom column that listed the values of those parameters at my color temperature settings. I published them to show you that I could achieve the desired result without sacrificing the monitor’s brightness. However, a brightness of 300 nits is too high for work, so you can reduce the contrast and brightness settings to your taste, as described in the previous section, having saved the above-mentioned color temperature setup.
To make sure the setup is correct, I will place dots corresponding to the different modes and levels of gray on a typical CIE diagram. The black curve on the diagram denotes all possible values which the human eye perceives as white. If the dot is higher than the curve, white has a green hue. If the dot is lower, white has a pink hue.
So, my manual setup is nearly ideal. The preset color temperature modes are but slightly shifted towards green. You can hardly notice it with an unaided eye.
The average nonuniformity of white brightness is 5.7% with a maximum of 25.1%. There is a dark spot in the top right corner (to remind you, what you can see above is not a photograph but a diagram built within the picture of a monitor). If the screen is all black, the right side is darker, too. There are no conspicuously bright spots and the results are quite satisfactory: an average nonuniformity of 3.5% with a maximum deflection of 17.9%.
The response time average is 6.8 milliseconds (GtG) with a maximum of only 11.2 milliseconds. You can play dynamic games on this monitor comfortably.
Of course, such a low response time is due to response time compensation. RTC technology can be accompanied with visual artifacts that show up as light or rainbow trails behind moving objects. This monitor is not free from them. The average level of RTC errors is 9.2% and the maximum error is 32%. These are normal results. You can spot RTC-provoked artifacts but they won’t be a big nuisance.
The Lenovo ThinkVision L220x would make a very good monitor for both home and office use if it were not for one problem. It features a neat, modest and appealing design and excellent ergonomics. Its response time is very low, but its main advantage is the PVA matrix. While nearly every other 22-inch monitor gets dark when viewed from below or bright when viewed from above, the L220x can be easily identified by its superb viewing angles.
Besides, the ThinkVision L220x has a nonstandard resolution for its diagonal. Its native resolution of 1920x1200 should be appreciated by people working with design drawings, large photographs and any other large piece of graphical of textual information. An important fact, the L220x is considerably cheaper than similar 24-inch monitors.
Alas, there is one problem. Some samples of the ThinkVision L220x have an inherent drawback that cannot be corrected by any settings. They have low image sharpness. I tried two samples but both were no good in this respect. One sample was in fact defective. The other was better, but not absolutely free from that drawback. So if you are going to buy an L220x, you should check its sharpness out at a resolution of 1920x1200 with DVI connection. This test is no less important for this monitor than checking it out for dead pixels.