With the development of LCD monitor technology and the decrease of monitor price, it is a fact that LCD will replace CRT and become the leading technology in monitor market.

1、The Preparation for Choosing a Monitor

(1)、Learn Something about Monitor Specifications

　As we know, the major cost of a monitor depends on LCD panel. 80% cost of a monitor is from LCD panel. The quality of a LCD monitor depends on the major specifications of LCD panel. Usually we use such specifications as brightness, contrast, response time, and viewing angle to evaluate the quality of a monitor. So it is necessary to learn something about these specifications before a monitor is purchased.

　 ＊Brightness: Brightness is a measurement that indicates the intensity of luminescence on the surface of an object. Its abbreviation is L and is expressed with cd/m2. The brightness of current leading LCD monitors is more than 250cd/m2 which can meet users’ requirements.

　 ＊Contrast: Contrast is the ratio of black color and white color or the gradient change from black to white. The larger the ratio is, the more the changes are. So the color will be more vivid. The contrast of current leading LCD monitor is 400:1 or even much more. Contrast is very important for vision. Usually, the larger the contrast is, the clearer the picture is. Instead, a small contrast will let the picture unclear, or vague. High contrast is very helpful for definition, details, and grey layer.

　 ＊Response Time: Response Time is the corresponsive speed of various pixels of LCD monitors vs input signals. i.e., the time that pixels change from dark to bright or vice versa. The usual specification, 25ms or 16ms, is the response time. A shorter response time can let an image to move without shadow. Usually, response time is divided into two kinds: rise time and fall time. Their sum is response time.

　 ＊GTG Response Time: Response time usually indicates the time needed from full dark to full brightness. A high drive voltage is needed when the screen changes from full dark to full brightness and the switching speed is fast. But in fact, most of screen switch is gray bar switch instead of dark-to-brightness switch. So at present, some manufacturers use GTG (Gray to Gray) response time to describe the function or specifications of a monitor (The truth is that the liquid crystal is converted, or transparent partially). The drive voltage needed is low. So the switching speed is slow. The current fastest GTG response time is 2ms. Usually, GTG response time is 8ms.

　 ＊Visual Angle: Visual Angle indicates the largest angle from which users can clearly see all content on the screen. Because the light of a panel is of direction due to refraction and reflection, the color will be distorted when an user is watching the screen out of the light range. Visual angle is different according to different panels. The horizontal visual angle is 160°for current popular TN panel.

(2)、Learn Something about LCD Panel

　Previously, we introduced a few important technical specifications. But there is a key factor that we can’t ignore when we buy a monitor. That is the panel of a monitor. The quality of a LCD monitor mainly depends on the type and quality of the panel. So it is very important for us to learn something about current leading panel type if we need to buy a monitor.

　The current leading panel manufacturers are Samsung, LG-Philips, and AU, etc. The panels can be divided into several types because of different technologies from these manufacturers. The usual type of panels is TN, IPS, and VA (MVA, PVA), etc.

TN Panel

　The full name of TN is Twisted Nematic Panel. The low production cost of TN makes TN become the most popular primary LCD panel. TN panel is widely used for the current leading monitors at middle or low price. All TN panels on current market are the improved type, named TN+film. Film is the compensation film and is used to improve the weakness of visual angle of TN panel. The visual angle of current improved TN panel can reach 160°. Of course, this is the maximal value tested under the condition of contrast 10:1 by manufacturers. In fact, the picture or color on the screen is distorted when the contrast is decreased to 100:1.

　As the panel with 6 bit, TN panel can only display 64 colors for Red/Green/Blue, respectively. The maximal colors are 262,144. With Dithering Technology, 16 million colors can be displayed. TN can only display three original colors from 0 to 252 colors gray bar. So the last color digit is 16.2M, instead of 16.7M. Also it is difficult for TN to increase contrast. As a result, the direct weakness is poor color, weak revivification, and weak transition.

　The advantage of TN panel is that the response time can be easily increased due to the fast deflexion speed of liquid crystal molecules because of less quantity of gray bar. All current LCD products with response time less than 8ms use TN panel. In addition, Samsung developed B-TN (Best-TN) panel which is actually an updated type of TN and reduces the conflict between high response time and low picture quality of TN. The contrast can reach 700:1 and approach the quality of MVA or early PVA panel.

VA Panel

　VA panel is widely used for high grade LCD products. In comparison with TN, it is its advantage that 8 bit panel can support 16.7M colors and visual angle is large. But the price is more expensive than that of TN. VA panel can be divided into MVA from Fujitsu and PVA from Samsung. The latter is an update for the previous one.

　Fujitsu MVA technology (Multi-domain Vertical Alignment, a multi-quadrant vertical technology) can be regarded as the earliest wide visual angle LCD panel technology. This sort of panel can support a wider visual angle with 170°. The visual angle of improved VA panel can reach 178°, near horizontal angle. And the response time can reach less than 20ms. With technical authorization, some Taiwan panel factories, such as CHIMEI and AUO, use this panel technology. Because of wide strong support from Taiwan panel factories, many cheap LCD panels with 16.7M colors and large size adopt MVA, such as Acer AL1913W, Viewsonic VG910s, and Benq FP991. Dell 1905 and Viewsonic VP191b are the typical models with high quality. Viewsoni VP191b reaches 8ms GTG gray bar and 178°visual angle with improved P-MVA and becomes the most advanced model among all LCD monitors with P-MVA.

　PVA panel was researched mainly by Samsung and is a successor and updated technology of Fujitsu’s MVA. Its brightness and contrast are better than that of MVA panel. Samsung’s 173/193P uses S-PVA and has the best contrast on current market.

IPS Panel

　IPS (In-Plane Switching) was invented by Hitachi in 2001 and its popular name is Super TFT. IPS is headed by Hitachi and supported by many factories, such as LG-Philips, Hannstar, and IDTech (a joint-venture corporation between Chi Mei and IBM), etc. But there are no many models on current market. Only Philips 190p5 is well-known. 16.7M colors, 170°visual angle, and 16ms response time are the most advanced specifications of current IPS panel.

How to Distinguish Various Panels with Your Eyes

　After we learn about the type of panel, we can distinguish the panel type of a LCD monitor from various specifications published officially. For example, the visual angle is 140°for primary TN panel, 160°for improved TN panel, and 170°or 178°for improved MVA/ PVA panel, as well as 160°for IPS panel and 170°for IPS panel.

　With the frequent improvement of panels, it is not enough to distinguish a panel only from visual angle. In fact, we can distinguish a panel with your own eyes. Now let us introduce the displaying style of various panels so as to distinguish the panel of a monitor according to different displaying effect.

　VA panel possesses the largest envisaging contrast, but the uniformity of panel is not quite good and the color may change stochastically. Sharp text is its key advantage. The contrast between black and white is quite high. Comparatively, it is a little easier to distinguish PVA among VA panel. You can confirm that the panel is PVA if the letter is soft, thin, and stereo after you open a text. In addition, the pixel of PVA is characterized with wavilness if you carefully watch its pixel.

　The uniformity of IPS is the most symmetrical with quite fine color. Especially when you carefully watch the panel, you can find that it is glittering and translucent. This is the best way to distinguish it. In addition, the display of its text is fine and persistent, differing from other panels.

　Comparatively, TN panel is a little rougher with low contrast of black/ white, large space between molecules, and thick stokes of letter. But it is not as easy as before to distinguish TN because TN panel has been improved much and its displaying style is similar with VA.

(3)、Attentions When Purchasing A Monitor

　Panel is not the unique standard to distinguish a LCD monitor although panel is the most important part of a LCD monitor. There are some more skills.

　 ＊Safe Port

　Monitor factories usually use D-sub port instead of DVI to save cost. Although the price can be decreased, DVI can support better displaying quality and decrease visual noise. So it is your first choice to buy a monitor with DVI port.

　 ＊Speaker is not important

　Although most of LCD monitors with speakers can meet the need of customers, the speakers become confusion for the customers who need high quality audio. Our proposal is that you’d better to buy a high quality sound box instead of speakers if you need high quality audio. If your space is limited, speakers are OK.

　 ＊Don’t Put Your Trust only to 16.7M Colors

　At present, a lot of customers have prejudice against the TN monitor with 16.2M colors. They think TN panel can not support good color. But in fact, with the constant improvement of TN panel, both contrast and brightness have been greatly improved. So the displaying quality accordingly has been improved. It is very difficult to differ 16.2M from 16.7M only with eyes. So we recommend that customers don’t put their trust only on 16.7M colors.  Comparatively, the advantage of TN monitor is its good performance-price ratio and fast response time. TN monitor is a good choice for beginners. As for VA or IPS monitor, the price is usually high. You’d better to choose according to your key need.