Most consumers are familiar with the term "LCD" from shopping for televisions. However, LCD is also utilised in computer screens. While many computer monitors used to employ CRT, or cathode ray technology, CRT screens are now close to obsolete, and are no longer manufactured. Today, modern laptop screens are typically a type of LCD screen that is attached to a keyboard to create a portable personal computer. LCD panels often refer to separate monitors used in desktop computers. Both modern laptop screens and LCD panels employ LCD, or liquid crystal display technology.
Whether a buyer is in the market for an LCD panel or a new laptop screen that employs LCD technology, there are a couple of things that an informed consumer should know. First, a buyer should be familiar with how LCD technology works. Second, the consumer should know what types of LCD laptop screens and panels are available. Finally, there are several features for a consumer to consider when shopping for laptop screens and LCD panels.
How LCD Technology Works in Laptop Screens and LCD Panels
LCD uses the light modulating capabilities of liquid crystals to bend in response to electric signal. First discovered in 1888, these light crystals possess light chemicals that align precisely when subjected to an electric field. When the light crystals are aligned, they allow light to pass through. A screen employing LCD is made up of multiple layers and a fluorescent light source, known as the backlight. Light passes through two polarised filters to create polarised light. The polarised light then passes through cells containing thousands of liquid crystals. One or more of these cells make up a pixel. Electric leads around the edge of the screen then create an electric field that twists the crystal molecules. This twist lines the light up with a second polarising filter, which allows light to pass through. Each pixel then comes through to create a sharp, focused image that is unique to LCD.
Types of Laptop Screens and LCD Panels
LCD is used in a wide range of electronic products, including laptop screens and desktop monitor panels. There are two major categories of LCD screens, including active matrix displays and passive matrix displays. Consumers should familiarise themselves with the following types of LCD screens, so they understand what type of LCD panel or laptop screen they are purchasing.
Active Matrix Displays
The first category is described as active matrix displays. This category is then broken down into three more sub-categories including, vertical alignment, twisted nematic, and in-plane switching. Active matrix displays are the most common type of LCD screen used in modern laptop screens and LCD panels.
Vertical Alignment (VA)
Vertical alignment refers to LCD where the liquid crystals naturally vertically align themselves with glass substrates. When no voltage is applied or when a device is "off", the liquid crystals sit perpendicular to the glass substrate creating a black display. When voltage is applied or when a device is "on", the liquid crystals move to a tilted position, which creates a variation of a grey scale.
Twisted Nematic (TN)
Twisted nematic LCD screens contain liquid crystals that twist and untwist at various degrees to allow light to pass through. When no voltage is applied or the device is "off", polarised light passes through a liquid crystal twist at 90 degrees. Depending on the amount of voltage applied, the liquid crystals untwist, changing polarisation and blocking the light's path. Any range of a grey scale is ultimately achieved with the right amount of voltage.
In-Plane Switching (INS)
In-plane switching refers to a display where the liquid crystals align parallel to the glass substrate. The electrical field is applied through opposite electrodes allowing the crystals to switch their position. Because this type of display requires two transistors for each pixel instead of a single transistor, it is not optimal for laptop screens because it requires a brighter backlight, requiring more power.
Passive Matrix Displays
The second category of LCD screens is passive matrix displays. This category is also broken down further into two sub-categories, including supertwist nematic and double layer STN. Although passive matrix displays are not often used in modern LCD screens, consumers should still be aware of this type of LCD screen.
Super-Twisted Nematic (STN)
Super-twisted nematic screens are similar to twisted nematic LCD screens, but instead of twisting at 90 degrees, super twisted nematic screens employ molecules that twist at 180 to 270 degrees. Super-twisted nematic screens were invented to allow passive-matrix addressing with a distinct threshold voltage. Although not used as often anymore, older laptop screens and LCD panels employ super-twisted nematic technology.
Double Layer Super-Twisted Nematic (DSTN)
Double layer super-twisted nematic screens are the same as super-twisted nematic screens except for that they provide an extra compensating layer to provide a sharper image. As a result, the double layer super-twisted nematic screen is easier to find in modern-day shopping of used LCD panels and laptop screens than some of the other passive matrix displays.
Features to Consider When Shopping for Laptop Screens and LCD Panels
While it is important for a consumer to grasp the meaning and types of LCD available for use in laptop screens and LCD panels, there are also several other things to consider when shopping for either a laptop screen or an LCD panel. Some of these features appeal to consumer preference and others are practical considerations.
Whether in the market for an LCD panel or a laptop screen, screen size is an important feature for a buyer to consider. Consumers should keep in mind that when shopping for a laptop, the overall size of the device increases as the screen size increases. For LCD panels, consumers have less co-dependent factors to consider. A consumer should simply determine what space is available for the LCD panel. LCD panels are available in a range of sizes, comparable to small television screens. LCD panels are typically available in size from 30.48 centimetres to 93.98 centimetres. Consumers should consider portability and weight when determining what size laptop screen to purchase. Buyers should aim for a laptop screen in the 27.94 centimetres to 43.18 centimetres range.
Both laptop screens and LCD panels measure screen resolution in pixels. The resolution is listed by horizontal pixel first by vertical pixel second. When these two numbers are multiplied together and the decimal is moved to the left, this determines the megapixel count. For example, an LCD panel with a resolution of 1280 x 1024 has a megapixel count of 1.3. Basically, the higher the megapixel count the sharper the overall image on the screen. That being said, consumers should still take screen resolution into consideration with other factors, particularly the screen size.
Glossy vs. Anti-Glare Screens
The standard LCD screen and laptop screen comes with a glossy display. Glossy displays are generally brighter and more vivid but also do not protect against glare. Anti-glare screens, on the other hand, are matte and protect against glare and external light sources. However, anti-glare screens brightness factor suffer as a result.
How to Buy a Laptop Screen and LCD Panel on eBay
Laptop screens and LCD panels are available in many sizes, resolutions, models, and brands.Whether you are in the market for a laptop screen or an LCD panel, eBay has a wide variety of options available for you choose from. For example, if you are looking for a new 50.8 centimetre LCD panel for your desktop computer, eBay has plenty of products matching that description. To see what options are available navigate to the eBay website portal. Once on the eBay home page, type 50.8 centimetre LCD panel into the keyword search box. After clicking the search button, a list of products matching that exact description is populated for you. If you are also shopping for a laptop screen, you can find what you need using the same method.
Like most electronics, both LCD panels and laptop screens are an investment. As a result, you should take advantage of eBay's Top-rated sellers function to ensure that you are purchasing quality products from reliable sellers. Top-rated sellers are those that provide accurate product descriptions, consistently deliver items, and charge fair postage. Further, you can be sure that these sellers are being monitored regularly to maintain this label. This is just one way eBay makes purchasing an LCD panel or a laptop screen accessible and hassle-free.
Today, both laptop screens and desktop computer monitors typically utilise LCD technology. While consumers do not need to be an electronics expert to make an informed choice when purchasing an LCD panel or laptop screen, a cursory knowledge of how LCD works and what types of LCD screens are available helps buyers make a more satisfactory purchase. Although passive matrix displays are no longer common in LCD panels and laptop screens, consumers purchasing used products benefit from understanding that a difference in LCD screens exists.
In addition to some general knowledge about LCD technology, consumers should also consider additional features of an LCD panel and a laptop screen. Purchasing an LCD panel or laptop screen requires consumers to choose at least a screen size and a screen resolution. Further, buyers should also understand that there are both anti-glare and glossy versions of LCD panels and laptop screens available. With some basic knowledge about laptop screens and LCD panels, even the amateur shopper has the necessary tools to buy a quality product.