The overhead projector, a reliable and straightforward device, projects images onto a screen or wall. It consists of a box housing a cooling fan and bright light. Extending above the box is a long arm with a mirror at its tip. This mirror catches and redirects the light towards the screen. Its purpose is to enlarge images for audience viewing on a screen or wall. Additionally, transparencies can be placed on the projector for both the speaker and audience to see.
The overhead projector, once widely used in classrooms and business meetings, has recently lost popularity to more advanced computer-based projectors. Originally introduced during World War II, it served as a training tool for large groups of servicemen before becoming common in classrooms and businesses in the 1950s and 60s. Its popularity soared by the 1990s, with almost every American classroom and business having one.
Despite the advancements in presentation technology, overhead projectors are still used for presentations in schools and businesses. This article provides a brief history of overhead projectors, including information about who invented them and their early uses.
Appledorn developed thermal-fax technology while working in the thermal-fax department at a company. Although a senior executive recognized his efforts, the company’s marketing team did not support his idea. Consequently, Appledorn and his co-researchers chose to independently market the technology.
According to another account, police identification work initially utilized an overhead projector. The first version of this projector featured a 9-inch stage with a cellophane roll that displayed facial characteristics. In 1945, during the final stages of World War II, the U.S. Army began using overhead projectors for training purposes.
In the late 1950s and early 1960s, overhead projectors became popular in schools and businesses. The leading manufacturer during this time was 3M, with Buhl Industries also entering the market and making technological advancements.
Throughout the 1980s and 1990s, overhead projectors remained important in classrooms. They were upgraded with liquid-crystal panels mounted in plastic frames that could be connected to computer video output. Initially, these projectors only displayed NTSC video output using monochrome LCD panels. However, over time they were replaced by color-capable models.
Finally, technology caught up with overhead projectors.
In the present day, overhead projectors have reached their maximum usage. In advanced nations, there are alternative presentation tools used in classrooms and businesses that are more interactive, computerized, and user-friendly. However, in less developed nations where technological progress is lacking, overhead projectors remain the preferred choice for business and educational presentations. The introduction of projection technology to Corporate America took place in the 1950s.
Despite significant technological advancements, the fundamental concept remains the same. In the 1950s, only opaque projectors were available. However, in the 21st century, there are various options based on the material to be projected. Opaque projectors enabled direct projection of printed material or small objects without conversion. For example, they could project a single page from a book onto a wall.
The opaque projector is a device that has been utilized for almost sixty years. It functions by shining a bright lamp onto the material being viewed and then directing the reflected light through a projection lens, projecting the entire book onto a page. It is capable of projecting various items including documents, photos, magazines, books, and small 3-dimensional objects. However, users should exercise caution regarding the heat produced by the light source as it may potentially harm heat-sensitive materials.
Slide projectors have been available since the 1950s, necessitating the transfer of material onto a 35mm slide. This enables users to project anything that can be placed on film. Despite the expense associated with creating slides, the advantage lies in the device’s versatility. Kodak, the primary provider of slide projectors, ceased production in October 2004. Nevertheless, other companies continue to include slide projectors in their product offerings.
An overhead projector works similarly to a slide projector by transferring information onto a transparent sheet called a transparency. A transparency can be created easily using a copy machine. This transparency is then placed on the projector and projected onto a wall or screen using a lamp and optics within the projector. One advantage of the overhead projector is the ability to make annotations on the projected image during a presentation.
Overhead projectors are still commonly used and in the late 1980s, they gained additional capabilities by incorporating digital projection panels. These panels consisted of a large LCD, electronics, cooling fan, and an enclosure made of plastic or metal with glass plates on both sides of the LCD. The size of the LCD resembled that of a notebook computer, but it had unfolded electronics on its back to allow light from the overhead projector to pass through.
The digital projection panel, housed in a box similar in size to a large book, functions like an electronic sheet of paper. When connected to a computer, it uses the light and optics of an overhead projector to show images. This essentially turns it into a large computer monitor, allowing for interactive presentations, educational sessions, and training activities. These panels were the first digital projectors and soon after came video projector panels. Shortly thereafter came multimedia projector panels that could handle both video and data at the same time.
While projection panels are still utilized, they are being swiftly replaced by data projectors, video projectors, and multimedia projectors due to the decreasing costs and improving performance. In the early 1990s, computer projectors emerged as a comprehensive integration of digital data projectors primarily used for business, education, and training purposes. This device effectively merged the overhead projector with the digital projection panel, resulting in a smaller and more portable design.
Computer projectors were initially large, heavy, and expensive, with lower image quality than today’s models. However, they have become smaller, lighter, and more affordable, which has made them popular among mobile presenters. Today, data projectors are used for various purposes including mobile presentations, conference rooms, classrooms, training sessions, gaming, simulation, control rooms, museums, and retail advertising.
Video projectors have evolved significantly since their introduction in the early 1990s. Initially, they were bulky and costly, with low image quality and limited mobility. However, advancements have resulted in home theater projectors that offer superior high definition movie experiences compared to local cinemas. These projectors provide an escape from inconvenient factors like dirty floors, overpriced snacks, and disruptive children in theaters. Moreover, video projectors can serve as TV projectors for streaming satellite receiver programming or local broadcasts. Modern TV projectors allow connections to DVD players and high definition DVD players, allowing users to enjoy their preferred movies. Some TV projectors even include built-in DVD players and audio systems, functioning as portable video boomboxes for effortless home entertainment that can be moved around effortlessly.
The market for home theater projectors is growing quickly, providing a more affordable option for individuals to create their own movie theater experience at home. This is especially attractive to DIY homeowners who prefer not to hire professional installers. Many enthusiasts have turned basements, spare bedrooms, and living rooms into personal theaters. With a home theater projector, these people can enjoy a large 100+ inch image at a much lower cost compared to LCD or plasma flat panels.
Many movie houses are replacing their film projectors with high definition digital projectors to compete with home theater systems. These digital projectors are larger versions of the ones used for home entertainment. In the past, multimedia projectors combined video, data, and audio in a universal solution. Nowadays, data and video projectors are essentially multimedia projectors as they all support data and video in various formats.
Despite their limited power and lack of separation, modern projectors can still be beneficial in small presentation rooms. Moreover, certain multimedia projectors provide wireless presentation and wireless high definition capabilities. At present, the latter functionality necessitates an additional device to enable connectivity between an HD projector and a high-definition video source wirelessly. However, it is possible that in the future this feature will become a standard aspect of projectors.
Pocket projectors were first introduced in 2005 by Mitsubishi. They were small enough to be held in the palm of a hand and used a group of LEDs for their light source. These projectors could be powered by either a wall outlet or battery. At first, they had an output of around 25 ANSI lumens, which was seen as a major drawback. However, advancements in technology are leading to a promising future for pocket projectors. Optics are being made smaller, light output is getting better, packaging is becoming more compact, and prices are becoming more affordable for consumers.
We anticipate the integration of technology into various devices, including toys and portable computers. This signifies that the projection industry has come full circle, as modern multimedia projectors now incorporate the capabilities of opaque projectors, slide projectors, and overhead projectors. This is made possible through the utilization of document cameras, which can be connected to any projector or integrated directly into the projector itself. Consequently, presenters now have the ability to project documents, transparencies, or 3-dimensional objects.
The speed at which performance improved and size decreased, along with the decrease in prices, is likely the most significant achievement in the evolution of this technology. As new technologies like lasers, LEDs, and electrode-less lamps emerge, we can anticipate smaller, lighter, and cheaper projectors with better resolution and performance in the coming years. The continued reduction in size will make pocket projectors a practical option. It appears that in the near future, consumers will be seeking an iProjector compatible with their iPod or iPhone.
