What is a projector?
A projector or image projector is an optical device that projects an image onto a surface, commonly a projection screen. Most projectors create an image by shining a light through a small transparent lens, but some newer types of projectors can project the image directly, by using lasers.
What are the different technologies used for projection and their difference?
DLP VS LCD Technology
Projectors can be classified by the technology used to project the content. Projectors can be used in colleges, at home as a home theatre as well as to play games. An impressive big screen can be used to entertain your guests as well as to make the visual more appealing. Large screens at sanctuaries and church projectors with more Lumens are used to show content to a large gathering. There are also gaming projectors available specifically for gaming purposes. Need help choosing between the different kinds of projector technology? We’re going to tell you the pros and cons of DLP vs LCD and all about LED projector technology.
What is an LCD projector?
LCD projectors use the same liquid display technology that can be found in electronic watches. An LCD projector creates images using a multistep process. First, a light source produces white light, which is then passed on to dichroic mirrors. The mirrors reflect the light adding colors, and then the beam of light is fed to an LCD panel. At that point, the LCD interprets the light and projects the corresponding image onto the screen. The LCD projectors are generally less expensive than their DLP counterparts. LCD projectors also offer better support for setups in larger rooms and home cinemas, as they are compatible with zoom lenses and lens shifts.
What is a DLP projector?
A DLP Projector uses the technology of Digital Light Processing. There is a DMD chip or digital micro-mirror device which consists of more than two million tinier mirrors. These tiny mirrors can move towards or away from the light source, to direct the light towards an image. It also consists of a spinning color wheel which delivers color and projects it on the screen. The light source used is LED or lamp. DLP projectors with the LED technology is easier to handle because the lamp doesn’t need to be replaced, saving both time and money. This kind of DLP projector is mainly used in classrooms and schools and colleges. They’re less expensive compared to the other technologies and are often used as home theater projectors. The color wheel which turns in front of the lamp is divided into several primary colors, and at the end, it reconstitutes all colors to give the final color.
Advantages and disadvantages of each
Advantages of DLP projectors
DLP projectors are easy to maintain since they have a filter-free and sealed chip design. They offer brilliant, colorful, clear images with good contrast. The final image on a DLP projector is much sharper because of the limited space between the pixels. Light loss on a DLP projector is greatly reduced, and the light output is high because of the use of mirrors. DLP technology offers a deeper black color compared to other projectors. DLP projectors produce a smoother image with no shadows.
Disadvantages of DLP projectors
The DLP has a limited number of pixels due to the mirrored chip, and it’s not as bright as LCD technology. DLP projectors can produce the rainbow effect with brief flashes of color across the screen.
Advantages LCD
The LCD projector is more light efficient and has a good color saturation. LCD projectors produce a brighter image with the same projector wattage and have high brightness capabilities. LCD projectors produce a sharper image which is more precisely focused. LCD projectors score higher when it comes to the brightness, an essential projector feature.
Disadvantages LCD
LCD projectors are bulky since they consist of too many internal components and are difficult to carry around. The LCD projector can fail fast, and the parts are expensive to replace. LCD projectors cause the image to look heavy with pixels, and color uniformity is lower than DLP. And finally, LCD projectors lose image quality over time.
What about an LED Projector?
LED is not a display technology. Instead, it’s a reference to the light source used. LED projectors have a significantly smaller footprint than those that use traditional projector lamps. LED projectors are similar to most other projectors. The only difference is the projector bulb. Rather than use a traditional projector bulb, these projectors use a combination of red, green, and blue LED’s. These LED’s use a low-heat, low-energy process of semi-conduction to generate energy, creating an electric signal which gives off a particle of light. The biggest advantage of LED projectors is the LED lifespan due to their lamp life and low heat output. LEDs last at least 10 times longer than traditional projector lamps. Many LED projectors can run for 10,000 hours or more. Since the lamp lasts the life of the projector, you don’t have to worry about buying new lamps.
In an LCD (liquid-crystal display) projector light from a single lamp is directed to a trio of miniature LCD panels that process the red, green, and blue light components separately. The pixels in each panel contain a liquid-crystal material that regulates the amount of light passing through them by twisting and untwisting in response to electrical voltages. After exiting the LCD panels, the three colored beams are combined by a prism and projected onto the screen by a lens.
Most DLP (Digital Light Processing) projectors have a single chip and a spinning colour wheel that chops white light from a lamp into a sequence of red, green, and blue beams (sometimes yellow and white too). The beams are reflected from the chip which contains hundreds of thousands of tiny mirrors. These mirrors pivot thousands of times a second to control the brightness of the pixels and are synchronized to display a red, green, or blue projection that the eye blends into a full-color image.
The Difference:
Ask us just 5-8years ago and we would have said there was a big difference in image quality and reliability between the 2 popular technologies, today though with so many changes occurring over the past decade there is very little difference. We generally recommend not to worry too much about the technology being used, the overall quality and suitability of a projector really comes down to the individual model. There are some great DLP's on the market and some great LCD's too.
In the past LCD was known for more accurate colours, a slightly sharper image, and for being more light-efficient, which means they produce brighter images using less power. LCD projectors were also known for some negatives such as a screen door effect and lower contrast/black levels. The screen door effect was basically the gap between the pixels making the image look like you were looking through a screen door.
All of these 'disadvantages' of LCD have been addressed by the brands so there are not too many negatives anymore. Over the past decade HD and FULL HD resolutions have pretty much removed the screen door issue and filters or an inbuilt Iris function has improved contrast substantially.
On the DLP side some positives were the improved smoothness of the image, no screen door effect (due to the pixels being closer), and improved contrast. Some negatives were that a small percentage of the population could see a "rainbow effect". This effect basically looks like a rainbow of colours across the screen and is typically visible when you move your eyes across the screen rapidly. This effect is only visible with a very small percentage of the population in varying severity. The rainbow effect is caused by the refreshing of the colours on screen as the colour wheel spins. As with the issues LCD projectors faced in the past the DLP companies have been working to improve the technology. DLP projectors now use faster colour wheels and use more segments... this improves colour reproduction and reduces the amount of people who can see the rainbow effect substantially.
As LCD and DLP technology are so similar nowadays when selecting a projector, it is best to compare the specifications and features and not to worry as much about the technology being used inside the unit, it doesn't matter as much as in the past since both technologies can produce brilliant pictures.
What is LED projector?
LED Projectors
Most projectors' light source is a high-pressure mercury lamp providing high brightness and a lamp life of up to 10000 hours. These then get replaced and cost around the $300 mark (depending on the model). Some of the newest ranges of projectors have replaced this with an LED light source which gives you a longer lamp life of 20,000 hours (never needing replacing).
"LED Projectors" generally have a brightness level between 50 and 1000 lumens, so much less than a lamp powered projector. This is fine for a small picture enough for half a dozen people or in a darkened room maybe around 10-15.
"LED Laser Projectors" are the newest addition to the projector lineup where the LED is boosted with a laser giving you the long lamp life with a high brightness between 2500 lumens and 4000 lumens allowing for use in conference rooms and classrooms.
Mini Pico & Ultra-Portable Projectors
With the new option of using LEDs to power a projector there is a new range of projectors that have become smaller and easier to carry. The smaller it is the less the power though so the pocket-sized projectors aren't recommended to use with large groups.
What is a PICO projector?
"Pico Projectors" are the smallest and most portable units around 250grams in weight and can sometimes even fit into a pocket. They are perfect for presentations with small groups up to 6 people. They will normally have around 100 lumens brightness limiting the presentation to a small image size.
"Mini Projectors" are a portable unit that can fit into a small case weight around 1kg and are perfect for presentations with small groups up to 12 people. They will normally have around 500-1000 lumens brightness limiting the presentation to a medium image size.
"Ultra-Portable Projectors" are a portable unit that can fit into a small case weight around 2kg and are perfect for presentations with larger groups up to around 50 people. They will normally have around 3000 lumens brightness allowing for presentations in lit rooms with a large image size.
What is a Laser Projector?
A laser projector is a device that projects changing laser beams on a screen to create a moving image for entertainment or professional use. It consists of a housing that contains lasers, mirrors, galvanometer scanners, and other optical components. A laser projector can contain one laser light source for single-color projection or three sources for RGB (red, green, and blue) full color projection.
Lasers offer potentially brighter projected images, with more and better colors.
Screen VS Wall projection?
Can you use a projector without a screen?
The simple answer is yes! But using a projector without a screen will decrease the quality of the viewable image.
A simple white wall will definitely provide a good surface for an image to be projected, but there are definitely some downsides to it. A wall does not reflect light near as well as a projector screen. The surface of a wall is also not as smooth as you would think. Get really close to the wall, and you will see what I mean.
Projector Screen vs Wall - Why you shouldn't use a projector without a screen
There are a couple of reasons that using a projector without a screen isn't ideal.
- The color of the wall and how reflective it is.
- Uneven texture of walls.
The Texture of the Wall
The uneven surface of a wall will likely cause problems with the projected image. A wall may appear flat and smooth, but most walls are not as smooth as they appear at first glance.
Run your hand across the area. You will likely feel imperfections such as small bumps and crevices. These small imperfections will cause tiny shadows to appear on the projected image. This will cause the image to be less bright and crisp overall.
If you have a cheap projector with a low-quality image then these imperfections won't impact the image quite as much. But if you have invested in a higher quality projector, then the small imperfections with have a profound impact on the image quality. A projector screen provides an ultra-smooth and highly reflective surface that a typical wall cannot compete with.
Projection terms:
- Lumens are the measurement of brightness that a projector gives out. In the industry, the formal term is “ANSI lumens.” ANSI being short for American National Standards Institute. The Projector Expert reports the following lumen counts of common light sources: Candle – 14 lumens. 100-watt light bulb – 1600 lumens.
- Throw Ratio tells us what image size we can project from a certain distance away. For instance, a throw ratio of 1.5 indicates that for every 1 foot of image width, the throw distance must be 1.5 feet. The smaller the throw ratio, the larger the image a projector will produce at a shorter throw distance.
Short Throw / Ultra Short Throw Projectors
The new buzz word in installation projectors is the short and ultra short throw range. These offer a much closer installation distance while still giving you a large image size.
The Benefits
Having a projector closer to the screen or wall avoids shadows of the presenter and stops the presenter from being blinded by the projectors light.
The Drawbacks
The optics involved in making the image larger make the projector heavier and larger. They have limits on the image size they can produce (normally up to 110"). The short throw projectors can also be more Expensive.
There are also two categories within short throw projectors; "Short throw" and "Ultra Short Throw" Projectors.
A "short throw" projector has a magnification lens and requires an installation distance of roughly 1-2metres for a decent image size.
"Ultra-short throw" projectors use magnification mirrors and allow for a closer distance normally within half a meter. These are usually more expensive and can be wall mounted just above the wall/screen further cutting down the throw distance.
Display Ratio
A projector's aspect ratio refers to the ratio between its width and height. For example, a 4:3 display produces an image that is squarer, where a 16:9 ratio produces an image that is more rectangular in shape.
- Projector Offsets
The offset measures the position of the image relative to the centerline of the lens. In a projector with a 0 percent offset, the center of the image lines up perfectly with the center of the lens, assuming that the projector is pointed straight at the screen. Most business projectors have a positive offset, allowing you to position them on a table and have them project upwards. For example, a projector with a 100 percent vertical offset would project an image whose bottom edge is in line with the center of the lens and that extends upwards. A 150 percent offset lens would project an image whose bottom edge is 50 percent of the image's height above the center of the lens.
- Focus
This function is used to make the image as sharp as possible. Every projector is equipped with either manual or auto focus. The manual focus allows the user to correct the projected image for the best projection manually while the projectors having auto focus do the same job automatically.
- Keystone Correction
When you position a projector well above the picture and point it down, or below the picture and point it up your image will appear a bit skewed. The same will happen if you have the projector off to the left or right of the image. the picture will end up having some distortion as per the below images.
Almost every projector now features Vertical Keystone Correction. This is a feature in the menu that allows you to manually adjust the image to 'square it up' or remove the distortion. Some projectors even have Automatic Vertical keystone correction that detects the angle in projection so does the correction automatically.
Horizontal keystone correction is not very common. It works the same as vertical keystone correction however fixes the distortion caused by having the projector too far left or right of the image.
Lens Shift is featured on some larger projectors which allows you to move the image up/down/left/right without the need to tilt or angle the projector. Because the projector is not being angled no keystone correction is required. As lens shift adds a fair bit to the size of the lens it is usually only featured on some larger home theatre projectors.
7. Resolution (sometimes referred to as “native resolution”) is defined as the number of pixels (i.e., individual points of color) that are used to create an image on a projecting image. It's expressed as the number of pixels on the horizontal axis by the number of pixels on the vertical axis
8. Contrast Ratio
A term defining how far the whitest whites are from the blackest blacks. If the peak white value is significantly different than the peak black value the signal is said to have high contrast resulting in well-defined sharp colours and shading. The Higher the better. A contrast of 400:1 means that the blackest black on the image will be 400 times darker than the whitest white.The contrast ratio is an important specification to look at should you be looking for a home theatre projector or when you wish to project in a darkened room. It is not of much importance for data/business projectors though as the contrast is usually washed out by the ambient light in the room.
9. HDR (High Dynamic Range) is a standard for displays that have the capability to show images with greater brightness and contrast, allowing the image to be shown more clearly, especially in terms of showing light and dark details and the color rendering of the image.
10. Color gamut is defined as the range of colors which a particular device can produce or record. It is usually shown by an enclosed area of the primary colors of the device on the chromaticity diagram. For example, the primary colors of monitors are red, green, and blue
11. Motion Estimation, Motion Compensation
MEMC stands for Motion Estimation, Motion Compensation. MEMC is a frame interpolation technique developed to enhance the quality and smoothness of the video. The process artificially adds additional frames between original frames.DSP
Indirect Light Mode
Brightness
The brightness of the projector (i.e., how bright the image will be) is rated by ANSI LUMENS.
The recommended brightness level varies depending on use and room conditions.
- Home theatre projectors will range from about 2000 lumens up to about 2500 lumens brightness. When you're watching a movie, you will most likely dim most of the light from the room, so a bright projector is not only unnecessary it will be overpowering in a dim room. Home theatre projectors generally focus on providing high detail, accurate colours, and high contrast to give the best picture possible.
- Presentations in a dim room allows you to decide from projectors around the 2000- 3000 lumen brightness level. Presentations require people to be able to read from charts sheets and other small texts and therefore you will need a little more brightness than home theatre.
- Presentations in a lit room will require from 3000 to 5000 Lumens brightness. This will ensure that the image is visible on the wall/screen in most lit rooms. Just remember the larger the screen and the brighter the room the brighter the projector will have to be. 3000 lumens are usually enough for a boardroom sized area, while 4000+ lumens is better for small halls or areas with lots of natural light.
- Larger venues presentations with a lit room/hall. In this situation I would recommend 4000 lumens and above. The larger the screen has to be and the more light that comes in the brighter the projector will have to be. For a 2m wide picture in a well-lit room 4000 lumens is normally fine, for a 4m wide picture in a well-lit room you would be best to jump up to around 6000 lumens or higher.
Noise
The noise rating of each projector is also a consideration. Basically, every projector has a very hot light source providing the light for the picture. The projector is equipped with fans that are designed to cool the light source and prolong its life. The fans will be quieter on Economic mode as you are basically turning down the lamps output and therefore the heat produced. Generally anything below 30 dB is fairly quiet. Home theatre projectors in particular should be quiet as you don't want to be sitting in suspense at a quiet point in the movie and hear an overwhelming buzzing noise from the fans.
When buying a portable projector, the noise level is generally higher; the fans will have to be smaller and spin at a faster rate to provide the same amount of cooling.
Projector noise ranges from 22dB for the large home theatre models, up to 40dB for the ultra-portable units.
Inputs
Many people do not really consider the importance of having the right inputs. You should pick a projector with the right connections for your equipment.
HDMI - High-Definition Multimedia Interface
This connection has basically taken over and is now featured on almost all projectors. It is the highest quality type of connection and is widely used on home theatre equipment as well as on computers. Be sure to use a v1.4 HDMI cable if you wish to play 3D, the older v1.3 HDMI cables cannot transmit 3D signals.
DVI
Digital Visual Interface. The DVI port is similar to the HDMI, as it also uses digital signals to transmit video to the projectors. It has become less common in recent years with many projector brands changing to HDMI. Picture quality between DVI and HDMI is the same.
D-SUB 15 pin (VGA)
Also called a D-connector, RGB, or VGA. A type of connector commonly found on computers, monitors, and projectors... D-type connectors have a "D-shaped" angled housing and have 15 pins.
VGA is still the most commonly found connector on a projector but is slowly being replaced with HDMI. VGA transmits in analogue so whilst picture quality is still quite good if you are using a FULL HD projector, we recommend using HDMI instead.
RCA (Component)
The higher quality analogue method of transmitting video signals, which operates by splitting up the red the green and the blue colours in the signal and then synchronizing them on the other end, making a clearer signal. Many projectors accept component through an adapter cable connecting directly into the 15pin D-sub (sometimes called the VGA port).
BNC (R/G/B/H/V)
(Bayonet-Neill-Concelman) - A not so common connector used to terminate coaxial cables. BNC is also referred to as Bayonet Network Connector. This is only used on a few large venue projectors.
S-Video
Small multi pin connector that carries separate brightness and color signals from a source component like a DVD player or satellite receiver to a TV set. This is an old-fashioned lower quality connection but is still featured on most projectors.
RCA (Composite)
A common, standard connection method used to transmit analog audio and video signals between devices. Commonly used on most receivers, televisions, satellite receivers, VCR's, game console systems and speakers. This is an older fashioned lower quality connection.
USB
This connection on projectors is used for two purposes:
1. Most commonly it is used as a feedback connection to the computer or laptop, allowing you to click next slide etc. on the wireless projector remote and control the presentation.
2. In some cases it is used with PC FREE presentation projectors allowing you to plug a USB memory stick into the projector and it can project with no PC straight through the projector. Some basic projectors will read picture files like Jpegs via this function and some will be able to do a proper presentation (after some formatting to the PowerPoint presentation.
3.5mm Jack
Much like the headphone connection on your Walkman or iPod, the stereo mini jack is used to transmit audio into the projector. In some projectors this connection is also used for the 12v Trigger function. This function can allow a motorized screen to lower automatically when the projector is turned on.
D-sub 9pin (RS-232)
Most commonly it is used for control when wiring a projector into a control panel on the wall. In Some cases, it is used for diagnosis when servicing.
RJ-45 (LAN Connection)
Some projectors allow you to connect to it through a normal network connection giving access to anyone on the network. This connection is predominantly used for control; turning on off and monitoring lamp life etc. Some projectors allow for the image to be sent via LAN.
Wireless WIFI (802.11b/802.11g/802.11n)
Some projectors come equipped with wireless connections. Allowing you to connect any PC and in some cases several PCs to the projector. This connection will in most cases require some software to be installed onto to computer
A wireless connection is not as good as a standard cable connection with a slower frame rate. For video a cable connection is recommended.
In some cases, an upgrade module will have to be connected or WiFi card through USB.
Both WXGA and WUXGA resolutions are widescreen, these are what we recommend for use with all modern computers (which are now widescreen too).
Resolution
A Native Resolution is essentially a measurement for the number of pixels being projected. The most common measurements for projectors are:
SVGA - 800x600
XGA - 1024x768
WXGA - 1280x800 (HD)
WUXGA - 1920x1080 (Full HD) or 1920x1200
Both WXGA and WUXGA are fine for fairly detailed presentations, obviously the higher the resolution the better though... so if you are projecting really high detail quite often it may be best to upgrade to a WUXGA model
For home theatre use there is really only 1 resolution to get, and that is WUXGA 1920x1080. This is FULL HD. All home theatre grade projectors now use this resolution.
Aspect Ratio (standard/widescreen)
The standard proportion in width to height for a projector used to be 4:3, but modern projectors have a widescreen format of 16:9 or 16:10. Almost all new computers are designed in the widescreen 16:10 or 16:9 formats so if the budget allows, we normally recommend getting a 16:9 or 16:10 projector (which means a WXGA or WUXGA resolution).
Lamp Life
A major concern of many projector buyers is the lamp life. Projector lamps can be expensive and while they differ from model to model, they generally range from $100-$400. Projector brands give a rating of lamp life with each projector so you know roughly how long the lamp usually will last for. If a lamp life is advertised as 'up to 5000 hours', this means on the most economic setting you should hopefully get near 5000hours of use. If you have the projector on a 'bright' mode you will get less hours.
Some models offer a long lamp life of up to 10,000 hours making them a very good buy in the long run.
While 3000 hours may not sound like much but even under fairly heavy use it does tend to last quite a while:
e.g. A 3000hour lamp used for 2 hours a day every day most likely will last you about 4 years.
There is now a new breed of projectors with LED and LED/LASER based lighting systems. These can offer the same image quality but with a much longer light source life. Some offer a lamp life of 20,000 hours and, although the light source is not replaceable, with a lamp life like that used for 2 hours a day every day it would last you up to 27 years. (Some LED based projectors will offer a much lower brightness so it is best to check the lumen rating in the specifications)