06 What kinds of monitors are available?
Description
This article is from the comp.sys.ibm.pc.hardware.video Frequently Asked Questions, by Michael Scott with numerous contributions by others. (v1.0).
06 What kinds of monitors are available?
Since there is a large variety of different types available, only some of the more common are listed here, along with their most common applications. In fact, it's difficult to define exactly what a 'kind of monitor' means. There are grayscale and colour, analog and digital, flat and not. I'll try to give some general answers.
Monochrome, Grayscale and Colour
This one's easy. Monochrome monitors can display two colours, usually black and one of white, green or amber. Grayscale monitors display only intensities between white and black. Colour monitors display combinations of red, green and blue, each in an independent intensity. Even though each colour is displayed only in one frequency (the frequency of light that a particular type of phosphor emits when excited) the combination of the three colours in different intensities fools the eye such that it perceives a full range of colours.
Analog and Digital
[From: Michael Scott (scott@bme.ri.ccf.org) and Sam Goldwasser (sam@stdavids.picker.com)]
Today, digital monitors are much less common than analog though in the days of CGA and EGA the situation was reversed. Digital does _not_ mean that the monitor has digital controls. Rather, it indicates that the monitor accepts a digital input signal. Examples of digital monitors include early monochrome, the IBM EGA and CGA. Digital monitors are limited by their internal hardware as to the number of colours that they can display. Most digital monitors use TTL signals (Transistor Transistor Logic). Note that some sales persons will call a new analog monitor 'digital', in reference to the controls. Strictly speaking they are wrong - see "Analog vs. Digital Controls" below.
Analog colour monitors can display an unlimited range of colours, since they accept an analog video signal. This means that the horizontal and vertical syncs, and actual video signals (usually red, green and blue) are analog. The total number of colours that a given computer system with an analog colour monitor can display is limited by the video card, not the monitor. It is rare for video cards to use digital-to-analog converters capable of generating more than 256 intensities per colour, so it is rare for systems to be able to display more than 256*256*256 equals 16.7 million colours. Analog monitors can have digital controls on the front panel, and have digital circuitry inside. The vast majority of monitors currently in use are analog, as they are more flexible than the digital variety and typically lower cost.
Most graphics cards put out an analog _or_ digital signal but not both. Similarly, most monitors accept and analog _or_ digital signal. It is feasible, however, to convert a digital video signal to analog and vice versa, though building such a device requires considerable electronics knowledge.
Shadow Masks and Aperture Grilles
By far the most common type of monitor uses a shadow mask, which is a fine metal grid which enables the electron beams for red, green and blue to only impact their proper phosphor dots. One alternative to this design is the aperture grille, which uses fine vertical wires for the same purpose. Sony first used this aperture grille in their Trinitron line.
Which one is better is not clear cut and is largely a matter of personal preference. Note that one complaint of Trinitron users is the presence of 1 or 2 very fine, almost invisible, horizontal stabilizing wires apparently needed to keep the fine aperture grill wires from moving out of place. You need to decide whether these will prove an unacceptable distraction. Trinitrons are usually considered to be brighter and sharper - but this is not always the case.
Analog vs. Digital Controls
[From: Michael Scott (scott@bme.ri.ccf.org)]
An analog monitor can have either analog (dials or knobs) or digital (buttons, sometimes with a dial) controls for brightness, contrast, screen size and position, pincushioning and trapezoidal shape, among others. Also, digital controls tend to be associated with a monitor's ability to store factory and user calibrations for image size and centering when operated at common video modes. This is desirable for a user who may be switching between DOS and windows applications often, so they don't have to be bothered with readjusting these controls after each change. Analog controls have the benefit of being infinitely adjustable, while digital controls are limited to a number of discrete steps for each adjustment.
Flat Panel vs. Conventional Tubes
Cathode ray tubes (CRT's) are the most common, inexpensive and best performing displays available for most users. Variations of CRT's exist including older designs with double curvature, some with only curvature in the horizontal plane (like Sony Trinitrons) and others which are called flat screen.
Flat panel displays are usually used in laptops because of their small size, but are expensive to manufacture and don't provide the high refresh rates and bright colours that conventional CRT technology provides. Flat panel displays range from monochrome LCD (Liquid Crystal Display) to dual scan colour to active matrix colour. Because of the difficulty of manufacturing these displays, and the fact that currently their primary application is in laptops where the maximum display size is usually less than eleven inches, high resolution flat panel displays are rare and expensive. In future, it's very likely that flat panel displays will replace conventional CRT technology for many home and business computer users.
Continue to:
My Books
