Editing Overhead projector (section)

=== LCD overhead displays ===
{{Main|LCD projector}}
In the early 1980s–1990s, overhead projectors were used as part of a classroom computer display/projection system. A liquid-crystal panel mounted in a plastic frame was placed on top of the overhead projector and connected to the video output of the computer, often splitting off the normal monitor output. A cooling fan in the frame of the LCD panel would blow cooling air across the LCD to prevent overheating that would fog the image.

The first of these LCD panels were monochrome-only, and could display [[NTSC]] video output such as from an [[Apple II]] computer or [[Videocassette recorder|VCR]]. In the late 1980s, color models became available, capable of "thousands" of colors (16-bit color), for the color [[Mac (computer)|Macintosh]] and [[Video Graphics Array|VGA]] [[IBM PC compatible|PCs]]. The displays were never particularly fast to refresh or update, resulting in the smearing of fast-moving images, but it was acceptable when nothing else was available.

The Do-It-Yourself community has started using this idea to make low-cost home theater projectors. By removing the casing and backlight assembly of a common LCD monitor, one can use the exposed LCD screen in conjunction with the overhead projector to project the contents of the LCD screen to the wall at a much lower cost than with standard LCD projectors. Due to the mirroring of the image in the head of the overhead projector, the image on the wall is "re-flipped" to where it would be if one was looking at the LCD screen normally.