Introduction to PC monitors
A PC monitor is a visual output device (display – sometimes called a visual display unit or VDU) which outputs dynamic images from devices such as PCs. PC monitors are an essential component of most modern PCs, and without such a device the computer would be simply useless. Monitors come in a range of different sizes and enclosures, and like the technology inside, the size and aesthetics have evolved alongside the PCs themselves. This article explores the turbulent life of PC monitors – from their birth, to their modern-day guise, to where they are likely headed in the future.
History of PC monitors
Early PC monitors were integrated into a package known as a “computer terminal”. Computer terminals comprised of an input area (i.e. keyboard) and an output area, connected to a computer via serial connection. The output area was, initially, the paper used by a teleprinter, but later a display unit – an early monitor replaced this paper. The monitors used in these (now archaic) computer terminals were referred to as TTL monitors, due to them interfacing with TTL (transistor-transitor logic) chips.
The earliest form of TTL monitors, introduced in the 1960s, were monochrome – they displayed text and simple (think blocks of a few shades of one colour moving around the screen) graphics in either a Matrix-esque green, amber or white (referred to as ‘page white’, as used in the earliest television sets). The monochrome colour displayed depended on the phosphor used to light up the monitor. These simple monochrome TTL monitors are still in use today in some places, for example in some cash registers, but are largely being phased out by superior and more modern PC monitor technologies.
A later form of TTL monitor, the CGA (computer graphics adaptor) monitor, interfaced with an IBM CGA graphics card. Introduced in 1981, the CGA card allowed the monitor to display a more complex image; comprising of 16 colours (4-bit) produced by firing red, green and blue cathode ray guns. The intensity of the colours could also be shifted, but unlike later PC monitors; this was not done independently for separate colours. Independent intensity control was a feature of the EGA (enhanced graphics adaptor) monitors introduced in the early 1980s, which had separate intensity control for each of the three cathode ray guns. This allowed a broader spectrum of 64 distinct colours to be displayed by the monitor.
In 1987, IBM introduced a standard of PC monitor whose siblings are still in (declining) use today; the VGA (video graphics array) monitor. As with the aforementioned monitors, VGA monitors were based on CRT (cathode ray tube) technology. The VGA standard allowed images to be displayed in 256 colours (8-bit) at 70Hz, although later “sibling” technologies allowed a much broader colour depth, higher refresh rates and higher resolutions. Confusingly, VGA became the name for the standard analogue PC monitor connector still in use today – and several display standards which are offshoots of VGA technology (such as WSXGA+ used mainly in 20-22″ widescreen PC monitors) may or may not use VGA connectors nowadays. VGA connections have now been superseded by digital connectors such as DVI (Digital Visual Interface), HDMI (High-Definition Multimedia Interface) and DisplayPort.
Current PC monitors
Liquid crystals were first discovered in 1888 by Friedrich Reinitzer, an Austrian botanist. Electronic devices such as calculators and alarm clocks have pixels filled with liquid crystals to produce vivid, bold and distinct black letters and numbers for several years. A modern adaptation of this technology, the TFT LCD (thin film transistor liquid crystal display) monitor is now the technology of choice for most modern PC monitors. Early TFT monitors were plagued by ghosting – a phenomenon caused by slow changeover of pixel colour (a poor response time). Additionally, the colour reproduction and contrast ratio offered by the displays was not on par with that of the standard CRT monitors of the time. Add to this the higher cost of TFT LCDs to the consumer, and they were by no means the technology of choice.
Throughout the 21st century, PC monitors have continued to evolve, and the aforementioned disadvantages of early TFT LCD monitors have been nullified. TFT LCD monitors now offer fantastic response times (usually below 8ms, sometimes as low as 2ms claimed) meaning that ghosting is not an issue. Contrast ratios as high as 50,000:1 are declared by some manufacturers and colour reproduction is excellent (probably better than even the highest end CRT monitors); so the images displayed are bright, vivid and full of life. Additional advantages over CRT monitors such as lower weight, much smaller dimensions for a given screen size (hence the term “flat screen”), lower power consumption, automatic viewable area adjustment and no refresh rate induced flicker, coupled with a now truly affordable price tag mean that they are now the PC monitors of choice for consumers.
Although such PC monitors do not have a true refresh rate in the CRT monitor sense, as liquid crystals merely act as shutters for a constantly lit backlight, the refresh rate is still important in gaming. The standard ‘refresh rate’ of nearly all modern PC monitors is 60Hz. Although obviously this doesn’t give the headaches and eyestrain associated with a CRT refreshing at a mere 60Hz, it does mean that any moving images displayed above 60 fps will become distorted. For this reason, most graphics card (GPU) drivers and 3D applications will allow enforcement of v-sync (vertical synchronisation) – so that the frame rate will remain at or below 60fps and no distracting visual artifacts such as momentarily misaligned textures will be observed. Despite the visual distraction, some gamers endure this somewhat disruptive experience to gain some extra performance, and forego the v-sync. Recent and future developments in PC monitors, however, may put an end to this compromise.