Pinhole Camera
Projectors share a common history with cameras. As far back as the 4th century BC, Greeks such as Aristotle and Euclid wrote on naturally-occurring rudimentary pinhole cameras. For example, light may travel through the slits of wicker baskets or the crossing of tree leaves. (The circular dapples on a forest floor, actually pinhole images of the sun, can be seen to have a bite taken out of them during partial solar eclipses opposite to the position of the moon's actual occultation of the sun because of the inverting effect of pinhole lenses.)
It was the 10th-century Ibn al-Haytham (Alhazen), who published this idea in the Book of Optics in 1021. When Ibn al-Haytham began experimenting with the camera obscura, he himself stated, Et nos non inventimus ita, "we did not invent this". He improved on the camera after realizing that the smaller the pinhole, the sharper the image (though the less light). He provides the first clear description for construction of a camera obscura (Lat. dark chamber). As a side benefit of his invention, he was credited with being first man to shift physics from a philosophical to an experimental basis. In the 13th century, Robert Grosseteste and Roger Bacon commented on the pinhole camera. Between 1000 and 1600, men such as Ibn al-Haytham, Gemma Frisius, and Giambattista della Porta wrote on the pinhole camera, explaining why the images are upside down. Pinhole devices provide safety for the eyes when viewing solar eclipses because the event is observed indirectly, the diminished intensity of the pinhole image being harmless compared with the full glare of the Sun itself. SOURCE: O'Connor, J.J. & Robertson, E.F. 2002. Light Through Ages: Ancient Greece to Maxwell. Retrieved from: http://www-groups.dcs.st-and.ac.uk/~history/HistTopics/Light_1.html Retrieved: July 14, 2015 |
Magic Lantern
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The magic lantern or Laterna Magica is an early type of image projector employing pictures on sheets of glass. It was developed in the 17th century and commonly used for educational and entertainment purposes.
There has been some debate about who the original inventor of the magic lantern is, but the most widely accepted theory is that Christiaan Huygens developed the original device in the late 1650s. In the fifteenth century, however, Giovanni Fontana, a Venetian engineer, had already created a lantern that projected an image of a demon. Even in its earliest use, it was demonstrated with monstrous images such as the Devil. Huygens's device was even referred to as the "lantern of fright" because it was able to project spooky images that looked like apparitions. In its early development, it was mostly used by magicians and conjurers to project images, making them appear or disappear, transform from one scene into a different scene, animate normally inanimate objects, or even create the belief of bringing the dead back to life. The magic lantern used a concave mirror in back of a light source to direct as much of the light as possible through a small rectangular sheet of glass—a "lantern slide"—on which was the painted or photographic image to be projected, and onward into a lens at the front of the apparatus. The lens was adjusted to optimally focus the plane of the slide at the distance of the projection screen, which could be simply a white wall, and it therefore formed an enlarged image of the slide on the screen. SOURCE: Akanegbu, A. 2013. Vision of Learning: A History of Classroom Projectors. Retrieved from: http://www.edtechmagazine.com/k12/article/2013/02/vision-learning-history-classroom-projectors Retrieved: July 14, 2015 |
Opaque Projector
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The Episcope, one of the earliest opaque projectors was sold by a German toy manufacturer in 1900 and used to project postcards, pages of the book, photos or 3d objects like insects, leaves, coins etc. into the wall.
Opaque projects began being used in corporate America in the 1950’s. SOURCE: (____). 2011. History of Projectors. Retrieved from: http://personal.frostburg.edu/cmedwards0/Modern.html Retrieved: July 14, 2015 |
Filmstrip Projector
Filmstrips were used to show educational films in classrooms, serving as a predecessor of videocassettes, DVDs and Blu-ray technology. Filmstrip projectors allowed teachers to pause presentations for class discussions by turning a knob, and the projectors were widely used in classrooms until VCRs replaced them in the 1980s.
SOURCE: Akanegbu, A. 2013. Vision of Learning: A History of Classroom Projectors. Retrieved from: http://www.edtechmagazine.com/k12/article/2013/02/vision-learning-history-classroom-projectors Retrieved: July 14, 2015 |
Slide Projector
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Slide projectors were introduced in the 1950’s. This technology works by transferring presentation material onto 35mm slides, therefore projecting anything that can be put onto film. The leading supplier, Kodak only discontinued its production in October 2004.
SOURCE: Badger, S. (____). The History of Slide Projector. Retrieved from: http://www.ehow.com/facts_6763648_history-slide-projector.html Retrieved: July 15, 2015 |
Overhead Projector
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Overhead Projector Overhead projectors evolved from slide technology in the 1950’s. They are similar to slide projectors in that for information to be viewed needs to be transferred onto another material ie. Transparencies. By the 1980’s overhead became commonplace in school classrooms, universities and businesses. In the mid 1990’s a decline in sales and use of overhead projectors began with the advancement of monitors and displays such as the document camera. The overhead projector continues to be widely used today.
SOURCE: (____). (____). Mobilizing Minds: Teaching Math and Science in the Age of Sputnik. Retrieved from: http://americanhistory.si.edu/mobilizing-minds/overhead-projectors Retrieved: July 15, 2015 |
Data Projector
A data projector takes signals from a video source, such as a computer or television, and projects an image on a projection screen. Early data projectors used a single cathode ray tube (CRT) to project a monochrome image, according to PC Magazine. CRT projection systems have since given way to lighter and more convenient projection technologies, such as liquid crystal display panels (LCD) and digital light processing (DLP).
SOURCE: Akanegbu, A. 2013. Vision of Learning: A History of Classroom Projectors. Retrieved from: http://www.edtechmagazine.com/k12/article/2013/02/vision-learning-history-classroom-projectors Retrieved: July 14, 2015 |
Document Camera
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The document camera came into use in 1988. Document cameras are used to display 3D objects, pages from books, artwork etc. Documents cameras are used in educational institutions, companies to provide training, courts to present evidence, science and medical research, business presentations etc. and are still widely used today.
SOURCE: (____). (____). What is a Document Camera Used For. Retrieved from: http://www.documentcameraexperts.com/Canada/learn_about_document_cameras.aspx Retrieved: July 15, 2015 |
Computer Projector
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The computer projector is a digital data projector that came onto the market place in the early 1990’s. They were mainly used as a computer display projector for education, business and training.
In the beginning of their existence computer projectors were big, heavy, and expensive with poor image quality compared to today. With the advancement of computer projector technology they became cheaper, lighter and more popular. They continue to be popularly used in conferences, classrooms, training, gaming, museums, retail advertising etc. SOURCE: (____). (____). LCD Projector's History. Retrieved from: https://projectorguide.wordpress.com/lcd-projectors-history/ Retrieved: July 15, 2015 |
3D Projector
Implementing 3D technology in schools became more affordable in 2010, when manufacturers included DLP chips in their projectors.
In 2011, the Boulder Valley School District in Colorado piloted 3D projectors to impressive results. Projectors marked “3D Ready” are able to produce two virtually simultaneous images. Then, with the use of active or passive glasses, images are streamed to the wearer’s eyes, according to Projector Reviews. Active 3D glasses feature electronic shutters that flicker to ensure the right picture goes into the correct eye. Passive 3D glasses show the two images superimposed on each other before the polarized lenses filter the images to each eye. SOURCE: Akanegbu, A. 2013. Vision of Learning: A History of Classroom Projectors. Retrieved from: http://www.edtechmagazine.com/k12/article/2013/02/vision-learning-history-classroom-projectors Retrieved: July 14, 2015 |