An overhead projector is a very basic but reliable form of projector. The overhead projector displays images onto a screen or wall. It consists of a large box containing a cooling fan and an extremely bright light, with a long arm extended above it. At the end of the arm is a mirror that catches and redirects the light towards the screen. An overhead projector can be used to enlarge images onto the screen or wall for audiences to view. Transparencies can be placed onto the projector to be viewed by both the audience and the speaker.
The overhead projector was once a common feature in both classrooms and business meetings. Recently, it has seen a decline in use, as more sophisticated computer based projectors are favored. The overhead projector was first seen during World War II. It was used as a tool to train large numbers of servicemen. In the 1950s and 60s, it crossed over into the classroom as an educational tool, and then into the business world as a training tool. The overhead projector reached its sales peak in the 1990s, when almost every classroom and business place in America had one installed.
Brief History of Overhead Projector Overhead projectors continue to be used for presentation purposes in both school and business settings despite the advancements in presentation technology. Read on to learn the humble history of, who invented and the early uses of the overhead projector. * Overhead Projector - The Early Days Who invented the overhead projector? Unfortunately, various sources do not identify a single person. It has been said that a certain Roger Appledorn was responsible for the technology that was used for the first overhead projector.
Appledorn worked in the thermal-fax department of a company and worked on the technology when a top executive discovered what he was doing. Although it was impressive, the company's marketing team did not support Appledorn's idea. Appledorn and his co-researchers decided to market the technology themselves. Another popular account pointing to the beginning of the overhead projector said that the first overhead projector was used for police identification work. It was said that the first overhead projector sed a cellophane roll over a 9-inch stage that allowed facial characteristics to be rolled across the stage. In 1945, the U. S. Army used overhead projectors for training just as World War II was ending.
Then in the late 1950s and early 1960s, overhead projectors began to be used in schools and businesses. Surfacing in those days was 3M, the company that became the foremost manufacturer of overhead projectors. As demand for overhead projectors increased, another company, Buhl Industries, entered the market and contributed to the technological enhancements of overhead projectors. Fast Forward to the 80's During the 1980s-1990s, overhead projectors continued to be an essential tool for classroom learning. The technology then used a liquid-crystal panel mounted in a plastic frame that was placed on top of the overhead projector and connected to the video output of computers. Overhead projectors used monochrome LCD panels and could only display NTSC video output. Soon after, overhead projectors capable of handling color images took the place of the monochrome models. * Technology Finally Caught on to Overhead Projectors
Today, the use of overhead projectors has finally reached its peak. For advanced countries, other presentation tools are now being used in both classroom and business settings. These presentation tools are more interactive, highly computerized and easier to use. However, in less developed countries where technological advancement has not been fully realized, overhead projectors are still the top choice for business and educational presentations. The Evolution of Projection Technology Corporate America was first introduced to projection technology in the 1950s.
Although the technology itself has changed dramatically since that time, conceptually it has remained the same. The opaque projectors which were the sole option of the 50’s have given way to a multitude of options in the 21st century where one’s choice of technology will likely hinge on the material to be projected. Opaque Projectors - One of the earliest forms of projection, the opaque projector, allows the user to project printed material or small objects without having to convert them to another medium. | An example of such an application would be projecting the contents of single page of a book onto a wall.
This is achieved by turning to the page and placing the entire book into in the opaque projector. In use for nearly sixty years, the opaque projector projects the object by shining a bright lamp on the material to be viewed and directing the reflected light through a projection lens. Documents, photos, magazines, books, and small 3-dimensional objects can be projected with the opaque projector provided the user remains mindful of the heat generated by the light source and the potential for damage to heat sensitive documents or objects.
Slide Projectors - Slide projectors have also been around since the 1950's. | Unlike opaque projectors, slide projectors require that the presented material be transferred to a 35mm slide allowing the user to project virtually anything that can be can put on film. While there is a cost associated with creating slides, the benefit is the versatility of the device. Kodak, the leading supplier of slide projectors, discontinued production in October 2004. Regardless, there is still a market for slide projectors as other companies still include them in their product lineup. |
Overhead Projectors - In some ways an overhead projector is very much like a slide projector in that the information to be viewed must be transferred to another medium, in this case a transparent sheet of flexible material known as a transparency. A transparency of any document can be easily generated with a copy machine. Once created, the transparency can be placed on an overhead projector and projected onto a wall or screen using a lamp and optics that are built into the projector. One of the benefits of the overhead projector is the ability to annotate the projected image while presenting.
Overhead projectors are still widely used. Digital Projection Panels - In the late 1980's overhead projectors found further use with the introduction of digital projection panels. | The digital projection panel consisted of a large LCD, electronics, cooling fan, and a plastic or metal enclosure with a glass plate on both sides of the LCD. The LCD was similar in size to that found in a notebook computer except that the electronics on the back of the LCD were unfolded to allow light from the overhead projector to pass through the LCD.
A digital projection panel was essentially an electronic sheet of paper in a box about the size of a large book that when plugged into a computer could display the image using the light and optics of the overhead projector. It effectively became a giant monitor for the computer allowing fully interactive presentation, education, and training making them the first digital projectors. Within a year of their introduction, video projector panels were introduced and were quickly followed by multimedia projector panels that could support video and data.
Projection panels are still in use, but as prices drop and performance continues to improve, they are quickly being replaced by data projectors, video projectors and multimedia projectors. Computer Projectors - the fully integrated digital data projector came into existence in the early 1990's and served primarily as a computer display projector for business, education and training. | It essentially combined the overhead projector and the digital projection panel into one device making it considerably smaller and more easily transported.
As is true with most new technologies, the first offerings of the computer projector were big, heavy and expensive with image quality that pales in comparison to today's projectors. As the computer projectors got smaller, lighter, and cheaper they became popular with mobile presenters. Today data projectors are used in a wide range of applications including mobile presentations, conference rooms, classrooms, training, gaming, simulation, control rooms, museums, and retail advertising.
Video Projectors - The digital video projector also came into being in the early 1990's and like the early computer projectors, they were large, heavy and expensive. | They also suffered from poor image quality, high cost, and limited portability. But much has changed since the video projectors of the early 1990's arrived. Today you can buy a home theater projector and enjoy a high definition movie with quality that is comparable to or better than your local movie theater. And you don't have to worry about the sticky floors, xpensive popcorn and the talkative kid that keeps kicking your seat. Video projectors also serve nicely as TV projectors that can project your satellite receiver programming or local broadcasts. With today’s TV projector you can also attach a DVD player or any of the high definition DVD players and enjoy a movie of your choosing. There are even TV projectors with integrated DVD players and audio systems that provide a video boom-box for home entertainment that can be easily taken from room to room with minimum setup.
Home Theater Projectors - The home theater projector is perhaps the most rapidly growing market segment now that a home movie theater experience is possible for a very nominal cost for the do-it-yourselfer. | For those not inclined to install their own home theater projector, there are plenty of installers available for hire. Some of our home theater enthusiasts have converted basements, spare bedrooms and living rooms into home theaters. A home theater projector can achieve a 100+ inch image for a fraction of the cost of LCD or plasma flat panel.
These home theater systems now compete with the neighborhood cinema and to remain competitive many movie houses are replacing their film projectors with high definition digital projectors, a larger version of the type one would buy for the home. Multimedia Projectors - The early multimedia projectors combined video, data and audio as a universal solution. | Today’s data and video projectors are essentially multimedia projectors as almost all of them support data and video in one form or another.
Since a good audio system needs power and separation, today’s projectors do not serve well as a primary audio source for any high quality audio, but they can be useful in a small presentation room. In addition, some multimedia projectors support wireless presentations and wireless high definition. The latter is currently an add-on that allows an HD projector to connect to a high definition video source without the need to run wiring. In time this may become a common component of the projector.
Pocket Projectors - The first pocket projectors were introduced in 2005 by Mitsubishi and they were small enough to fit in the palm of a hand. | Their light source is a cluster of LEDs and most of them can be plugged into a wall outlet or powered by battery. Their biggest drawback is the lumen output which in the first few years of shipment, was about 25 ANSI lumens. The future of pocket projectors is very promising as optics are reduced, light output improved, packaging reduced, and prices fit for a consumer market.
We expect to see the technology in everything from toys to portable computers. Conclusion – The projection industry has come full circle. Today a multimedia projector brings back many of the features found on the opaque projector, slide projector and overhead projector through the use of document cameras. These handy devices can be connected to any projector, or in some cases, they are integrated into the projector, giving the presenter the opportunity to project a document, transparency, or 3 dimensional object.
What is perhaps the greatest achievement in the evolution of this technology is how rapidly the performance improved and the size diminished while prices continued to fall. In the coming years you can expect to see smaller, lighter and cheaper projectors with better resolution and performance as new technologies such as lasers, LEDs and electrode-less lamps emerge. Further reductions in size will make pocket projectors a functional reality. All the indicators point to a near future where consumers will be shopping for an iProjector to plug into an iPod or iPhone.