Projector. A projector or image projector is an optical device that projects an image (or moving images) onto a surface, commonly a projection screen. Most projectors create an image by shining a light through a small transparent lens, but some newer types of projectors can project the image directly, by using lasers. A virtual retinal display, or retinal projector, is a projector that projects an image directly on the retina instead of using an external projection screen.
The most common type of projector used today is called a video projector. Video projectors are digital replacements for earlier types of projectors such as slide projectors and overhead projectors. These earlier types of projectors were mostly replaced with digital video projectors throughout the 1990s and early 2000s (decade), but old analog projectors are still used some places.
Movie theaters use a type of projector called a movie projector. History of projectors[edit] Early history of projectors and cameras[edit] Plotter. Hewlett-Packard A0 Plotter 5785B Overview[edit] Pen plotters print by moving a pen or other instrument across the surface of a piece of paper. This means that plotters are vector graphics devices, rather than raster graphics as with other printers. Pen plotters can draw complex line art, including text, but do so slowly because of the mechanical movement of the pens. They are often incapable of efficiently creating a solid region of color, but can hatch an area by drawing a number of close, regular lines. Plotters offered the fastest way to efficiently produce very large drawings or color high-resolution vector-based artwork when computer memory was very expensive and processor power was very limited, and other types of printers had limited graphic output capabilities. Pen plotters have essentially become obsolete, and have been replaced by large-format inkjet printers and LED toner based printers.
Cutting plotters[edit] History[edit] Label plotter Another approach, e.g. Vinyl cutter[edit] Printer (computing) HP LaserJet 5 printer This is an example of a wide-carriage dot matrix printer, designed for 14-inch (360 mm) wide paper, shown with 8.5-by-14-inch (220 mm × 360 mm) legal paper. Wide carriage printers were often used in the field of businesses, to print accounting records on 11-by-14-inch (280 mm × 360 mm) tractor-feed paper. They were also called "132-column printers" In computing, a printer is a peripheral which makes a representation of an electronic document on physical media. Consumer and some commercial printers are designed for low-volume, short-turnaround print jobs; requiring virtually no setup time to achieve a hard copy of a given document.
The world's first computer printer was a 19th-century mechanically driven apparatus invented by Charles Babbage for his difference engine.[1] A virtual printer is a piece of computer software whose user interface and API resembles that of a printer driver, but which is not connected with a physical computer printer. IBM 1403 line printer. Computer monitor. A monitor or a display is an electronic visual display for computers. The monitor comprises the display device, circuitry and an enclosure. The display device in modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD) thin panel, while older monitors used a cathode ray tube (CRT) about as deep as the screen size. Originally, computer monitors were used for data processing while television receivers were used for entertainment.
From the 1980s onwards, computers (and their monitors) have been used for both data processing and entertainment, while televisions have implemented some computer functionality. History[edit] Early electronic computers were fitted with a panel of light bulbs where the state of each particular bulb would indicate the on/off state of a particular register bit inside the computer. In time this array of light bulbs was replaced by a cathode ray tube which could display the equivalent of several dozen light bulbs with greater reliability. Computer speaker. A pair of speakers for notebook computers that are powered and audio-connected to the computer via USB Computer speakers range widely in quality and in price. The computer speakers typically packaged with computer systems are small, plastic, and have mediocre sound quality. Some computer speakers have equalization features such as bass and treble controls. The internal amplifiers require an external power source, usually an AC adapter.
More sophisticated computer speakers can have a subwoofer unit, to enhance bass output, and these units usually include the power amplifiers both for the bass speaker, and the small satellite speakers. Some computer displays have rather basic speakers built-in. For some users, a lead connecting computer sound output to an existing stereo system is practical. Common features[edit] A common computer icon representing a speaker Features vary by manufacturer, but may include the following: Cost-cutting measures and technical compatibility[edit] See also[edit]