Last updated on December 9th, 2019 at 05:51 pm
The history of projectors: An introduction
Projectors are designed solely for film: A funny misconception. In fact, projection came about long before we even imagined it possible to create moving images. As such, we’ve compiled the history of projectors to help with your understanding! From basic light theory to 4k, we’ve covered it. So take a step forward and we can show you just how far projection has come.
The history of projectors: Before Electricity
The pinhole camera
The earliest recording of the pinhole camera dates back to the 4th Century BC. Most of us have had experience with a pinhole camera in school, whether we remember it or not.
The pinhole relies on light travelling in straight lines (rectilinear theory of light), in order to produce images.
There are 3 components in a pinhole camera:
- Small pinhole opening for light
- An otherwise completely dark room or box
- Directed light
The pinhole camera directs light through an opening, thus displaying a live image onto the back wall of your box or room.
Because of the direction the light travels, the image appears upside down. This is called “Camera Obscura” and has helped build the foundation of modern day cameras.
The pinhole is hailed as the first camera. However, the projection of a live image using basic light is applicable to projectors too – especially in room based pinhole cameras.
It’s important to note that because pinhole cameras use natural light, the projected image appears very dimly and can only be seen without other forms of ambient lighting.
Christiaan Huygans developed the first “entertainment based” projector in the 17th Century. Similarly to the pinhole camera, this utilised directing light to project.
The magic lantern used a combination of:
- Light source
- Rectangular pinhole
- Concave mirror
Originally, the light source used for a Magic Lantern would have been multiple candles. Later, in the late 19th century bulbs were used. The light used in a magic lantern must be bright enough to direct into an otherwise dark room. In the18th century, the candle was constantly monitored to ensure this.
In Magic Lanterns a light source is directed into a rectangular pinhole, through hand painted glass image slides and onto a concave mirror.
As you know from the pinhole camera, light travels in straight lines making images appear upside down. Without the use of a tool to redirect the light, images in a magic lantern would appear like this too.
Because of this, a concave mirror was used to redirect the light, before passing it through the lens. From here, the image could be projected onto a wall the right way up.
However, in early models of this projector, there was no need for a concave mirror. The slides would be placed upside down into the projector. This would mean that the directed light would automatically put the image the right way up.
Opaque projector – 1756
Opaque projectors are a little harder to understand. The opaque projector was the first example of directing light through a series of prisms and mirrors in order to project.
Similarly to the Magic Lantern, the Opaque projector would use a bright light shined through a transparent object with image detailing (slides). However, the slides would be placed the correct way up and a series of prisms and mirrors ensure the image is projected correctly.
Explaining the science in full would take a whole new article. On that note, this is when the ability to project became a real science and difficult to attain for the masses.
Another thing the opaque projector allowed was the resizing of an image using a lens.
To Focus the image you had to resize the hole that directed the light source. To change the image size you had to adjust the lens. The lens controls how much light comes out of the Opaque projector, thus the size of the image.
The opaque projector spurred the creation of other forms of projector. However, these relied on the same mechanisms and until the rise in technology, projection didn’t progress too much.
Megascope – Used to project big images into lecture halls. Megascopes were used in elite universities throughout the 1700s and 1800s.
Henry Morton opaque projector – Invented in 1872 and made use of an oxyhydrogen lamp. This created a bright light source through the use of a concentrated flame. This allowed opaque projectors to appear brighter as they had a higher lumen count.
The history of projectors: The computer era (1940s -1960s)
The computer Era brought many exciting changes for projectors. This was the turning point into the world of quick technological development and helped encourage the demand for projectors.
The slide projector
One of the first electrical slide projectors invented was the KODASLIDE projector in 1937. Slide projectors mimic magic lantern and opaque projectors – Small glass slides are used in order to project images.
The difference here was the light source. Instead of an oxyhydrogen flame or candle, the slide projector used an incandescent bulb. This allowed the projector lumen to be a lot higher.
In turn, this meant these projectors could have larger, brighter images and were more forgiving in the presence of ambient lighting. However, the images projected could only be put in one at a time by hand, meaning they were still.
Bulbs were first used in slide projectors, thus creating bulb based projection and the foundation of modern projector technology.
The first overhead projector was produced in the 1870’s and worked based on the hydrogen bulb. Modern electricity based overhead projectors were invented in the 1940’s.
When we talk overhead projector nowadays, we mean those which hangs from the ceiling. However, back in the day “overhead” meant the projector took the image from below it using a lens, to then project onto a wall.
These were very handy to have as you could quickly change the content they projected. This meant their first use was for classrooms or business meetings to show graphs. In fact, they were often used by the military throughout the 20th century to present.
Overhead projectors were especially useful as they often had inbuilt fans that prevented the bulbs from overheating. This was and still is a common problem for lamp based projectors.
Nowadays however, overhead projectors have become somewhat obsolete. Instead, they have been replaced by digital projectors and whiteboards.
The history of projectors: The digital era (1970s – 1990s)
This era was incredibly important for projectors. Demand for projectors drove up production and technological advancement in this era.
The technologies discovered for projectors are the foundations of modern day projectors, which has made this period especially prominent.
One huge limitation of overhead projectors was their inability to project opaque documents.
Printing onto transparent screens is time consuming, specialised and expensive. So the next logical stage was to take the premise of the overhead projector and adapt to project paper documents.
That is exactly what the document camera set out to achieve. Instead of using light, this projector utilised upcoming technologies. The document projector has a camera that feeds live information to the projector to show over a screen.
Live feed made document cameras accessible to the masses as now paper documents could be used.
DLP projection was huge for the advancement of projectors. Up until this point, the only way movies could be shown through projection, was through quick slide rotation.
Old film reels used thousands of transparent slides, each showing different scenes with a manual rotation. As you can imagine, this was incredibly expensive and ineffective for showing videos.
DLP projection was invented in 1987 and uses a series of microscopic mirrors to block or reflect light. These mirrors are housed on a chip and each is representative of a pixel on the screen. Light passes through a colour wheel and onto the chip, which then opens and closes it’s mirrors to create various images.
The image feed from DLP projection comes from a variety of sources, but usually is input from a computer or video player. The more microscopic mirrors present on the chip, the more pixels and the higher the resolution of the projector. Nowadays we have 3 chip DLP projection.
LCD stands for liquid crystal display. This technology was first developed in the 60s, became commercially available into the 70s, but wasn’t used in projection until 1990. Since then, LCD projectors have become one of the most popular format of projection.
LCD works by sending light from a lamp through a prism or series of dichroic filters that separate light into three polysilicon panels. These panels represent red, green and blue: the basis of all colours. As the light shines on to these panels, individual pixels open or close in order to let the light pass through or block it.
Although LCD technology does source its light from a lamp which can overheat, the contrast and brightness levels it offers are incredible at its price point.
The history of projectors: Modern day (2010+)
HDMI + 4k projection
High resolution projectors were originally a clear reflection of either the mirrors present on a DLP chip or the number of pixels present in LCD projectors. Resolution is directly related to how many pixels an image has, the more pixels, the better the quality of image.
The development of 3 chip DLP projectors in the 2010s gave consumers access to high resolution projection.
However, with the growth in demand for 4k, projectors were forced to further adapt in order to compete. We haven’t quite reached the stage where we can offer 4k resolution natively in a projector.
Instead we’ve built projector technology that mimics the quality of 4k, without having the same number of pixels. This is done by using pixel shifting technology within projectors. Although this means technically projectors don’t offer 4k, pixel shifting has made high quality projection far more accessible whilst meeting demand.
Laser projection became available for cinemas in 2013 and offers high quality, 4k images. This projection was designed for cinema use as it offers huge brightness and contrast levels.
5 years ago laser projectors aimed at consumers were brought to the market. Although these are high in price, the quality levels they offer are unmatched and they combat some of the issues in lamp based projection.
Laser projection works through the combination of 3 lasers (red, green and blue), that flow onto a DMD chip(s). Some laser projectors use one laser that can mimic any colour to pass onto the DMD chip(s). Other than the light source and lack of colour wheel, laser projectors work in the same format as other DLP projectors.
SMART projectors are the direction that looks to become popular in the near future. Instead of needing a source for media, they have an operating system. In that sense SMART projectors are similar to computers or android systems. As such, you can watch Netflix or YouTube without having to have a HDMI input from a laptop.
SMART projectors take away the need to have more than one device when operating a projector and are the direction modern projectors are taking.
The history of projectors: Conclusion
Now that you understand exactly where your projector comes from and how the technology has developed, perhaps you have more appreciation for them. If this is the push you needed to get involved in the world of projection, let us know in the comments below. However, perhaps you’re still unsure of what modern projection is…then check out our ultimate projector guide. Nonetheless, you now understand the history of projectors, which is vastly more than most!
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