A monitor is the main output device of a computer. The two main types of monitors in use today are the liquid crystal display (LCD), also known as a flat panel display, and the cathode ray tube (CRT), which is older technology. Each has advantages and disadvantages.
Most of today’s older monitors use cathode ray tube technology, which was first developed for use in televisions. The cathode is a negatively charged electrode that shoots a beam of electrons toward a positively charged electrode, known as the anode. The cathode ray tube is a vacuum tube containing one or more electron guns (cathodes) at one end, which fire a stream of electrons onto a screen at the other end. The inside of the screen is covered with a dot matrix made of phosphorescent material, known as a phosphor. When phosphors are struck by electrons, they emit light. The phosphors are arranged in groups of three, known as pixels. Each pixel contains a dot that emits one of three basic colors: red, green, and blue. Magnetic coils in the tube control the direction of electron flow, and a control grid determines the color scheme on the screen. The flow of electrons starts at the top of the screen moving from left to right, line by line to build an image.
An LCD monitor, on the other hand, uses a layer of liquid crystal material sandwiched between two grids of electrodes, one arranged in columns and the other in rows. These grids, in turn, are surrounded by a layer of plastic or glass polarizing material. These polarizing layers are aligned to prevent the passage of light when the electrodes are not activated.
To generate an image, light passes through the first polarized layer. As the light passes through the liquid crystal material, the polarity changes to allow it to pass through the second polarized layer. This is done by manipulating the electrode grids. Pixels are made up of liquid crystal cells that change the direction of light passing through them in response to a grid of electrodes.
Today’s LCD monitors often use what is known as Thin Film Transistor (TFT) technology, in which a transistor is placed at each intersection of the electrode grids, improving the signal and therefore image quality. This is also known as an active matrix display, as opposed to the older technology known as a passive matrix display.
There are many features to consider when choosing a monitor. Some of the most important are: screen size, resolution, dot pitch, refresh rate, and response time. Screen size refers to the diagonal length of the screen surface. Resolution refers to the number of pixels the monitor can display, for example 640 x 480, which means 640 pixels horizontally by 480 pixels vertically. The more pixels displayed, the sharper the image will be. Dot pitch is the distance between dots, expressed in millimeters, such as 25mm, the lower the number, the better the image. CRT monitor refresh rate, or LCD monitor response time, is the rate at which a monitor generates an image. The faster the response time or refresh rate, the better the image.
Generally speaking, LCD monitors take up much less space than a CRT monitor and are lighter in weight. Also, LCD monitors use less electricity. However, they tend to be more expensive, although this can be partly offset in the long run by reduced electricity consumption.
CRTs typically have higher refresh rates than LCD monitor response times, which reduces eye strain and may be preferable for those who spend a lot of time in front of a computer. CRT monitors can display at various resolution settings, while LCD monitors use only one resolution, called the native resolution. This can present a problem for high-end games and graphic displays.
While LCD monitors were initially higher in price and lower in quality compared to CRT monitors when they first appeared years ago, technology has improved dramatically and LCD monitors now compare favorably in price and display quality with CRT monitors. LCD monitors are the monitors of the future and will eventually make CRT monitors obsolete. For more information on which are the best monitors to buy, click on Computer Monitors There you will find a comparison of the five best all-purpose LCD computer monitors.