Ultra-short-focus, short-focus and long-focus projectors are the three main categories into which multimedia devices can be divided. Their main difference from each other is the size of the distance between the projector and the image plane. Each type of device has its own niche and scope. Long-focus projectors are a classic, they were the first to appear, have a simpler technological solution and are used today mainly in large halls, cinemas. Short-focus devices are used more often in offices, at presentations, and finally ultra-short-focus ones, which will be discussed in this article, are convenient in apartments or in small training or office rooms.
Ultrashort-focus projectors: types, advantages, scope
What are the benefits of ultra- and short-focus projectors?
- They are located close to the screen, due to which it is possible to get rid of long cables and the installation process of the projector is simplified .
- Allows you to achieve widescreen images in a small room (movie theater effect).
- During the demonstration of the image, the light flux from the projector does not blind the audience and the speaker, and no shadows form from the teacher or those sitting in the hall on the screen.
The difference between an ultra-short-focus projector and a short-focus one is in the projection ratio. The projection ratio (or projection coefficient) is the ratio of the distance between the screen and the projector to the width of the screen. If the short-focus one has a magnitude of 0.5-1.5, then the second - less than 0.5, which allows you to get the image size diagonally up to two meters from a distance of less than half a meter.
The feedback from teachers, speakers about the operation of these projectors is enthusiastic, since the installation process of the projector has been simplified, special technical skills or invited installers are not required, and lectures and reports have become much more convenient and efficient.
Lens Mirror
Ultra-short throw projectors, in turn, are divided into two types: lens and lens-mirror. Lens-mirror is a new word in the development of projection technology. They are equipped with a special optical system consisting of a lens and a mirror. The luminous flux from the lens is not directed directly to the screen, but to the mirror, and from there the reflected image hits the screen. Thus, it is possible to reduce the projection distance to tens of centimeters. Classic lens models have less weight, but work from a greater distance to the screen. Installing such projectors is easier, since, as a rule, they come with a mounting rod and are mounted on the same wall as the screen. Also a plus, since often there are problems with mounting the projector to the ceiling in rooms with high heights.
Features of the operation of lens-mirror projectors
It should be noted that the use of ultra-short throw projectors places increased demands on the screen surface. Since the light flux falls on the reflecting surface at an acute angle, the irregularities and roughness of the screen create shadows, glare, which affects the image quality. Therefore, you need to use screens with a white or matte flat surface. We must pay tribute to the developers of ultrashort-focus projectors, they had to deal with uneven illumination of the screen (due to the sharp angle of incidence of the light flux, the edges of the screen farthest from the lens were illuminated with less brightness). I had to use non-standard software and hardware solutions, up to the use of free-form lens lenses, calculated according to complex programs. With the advent of projectors with such a small projection ratio, the scope of their application has expanded, including for advertising purposes. For example, in stores and markets in conditions of limited space advertising of services and goods has become possible.
Ultrashort-focus laser projectors
Laser projectors are a new branch of the development of projection technology. Unlike the classic ones, the light source in them is a laser emitter, and not a mercury lamp or LED. The advantage of this technology is the absence of any requirements for the reflection surface, there is no loss of definition, defocusing even on an uneven surface. The principle of obtaining images is similar to the method of obtaining images in vintage cathode ray tubes. A laser beam scans the surface 50 times per second and forms an image as a whole.
Advantages and prospects of a laser projector
Laser projector benefits:
- long life of a laser source up to 20,000 hours versus 3000-5000 for a lamp;
- consumes little power and runs quietly, since it does not require cooling;
- It does not require time for heating and cooling, it instantly turns on and reaches maximum brightness and also turns off at the same time;
- can create images on huge screens of several tens of meters;
- high contrast, creates a perfect black color, which is impossible in tube projectors;
- since there is no lens in it, with 30-40 centimeters it can produce a large image up to two meters.
Disadvantages of a laser projector:
- still very high cost;
- more weight than tube projectors.
According to experts, the future lies with laser projectors, since due to technological advantages, it is possible to unlimitedly increase the brightness of the light flux and the clarity of image detail.
Interactive projectors make learning more effective
Ultra-short focus interactive projectors make the learning process extremely convenient, interesting and productive. The interactive capabilities of devices today are ubiquitous in life - these are primarily our smartphones, screens in cars, payment terminals, etc. Of course, projector manufacturers could not help but give them interactive capabilities. The first came the ultra-short throw projector kits with a board. The kit consists of the projector itself, fasteners, an interactive whiteboard that determines the coordinates of touching the surface, and software that controls interactive functions. The device transfers the image from the computer to the board, which, using the built-in sensors, transfers the location of the stylus or finger back to the computer. Boards vary in size and type of sensors, their price depends on this. Optimal in terms of price / quality ratio are optical boards measuring 2.08 meters.
A more modern and perfect solution are short-range interactive projectors. They already have built-in interactive features. The built-in infrared radiation of the projector makes any surface interactive, and there is no need for an interactive whiteboard.
According to teachers, the interactive learning process is extremely convenient for the teacher, and for the student, student. Everything is clear, a lecture or lesson gets into the laptops of students along with notes made in the lesson.
LED projectors: advantages and disadvantages
The main difference between the ultra-short- focus LED projector and the others is that in it the light source is not an ordinary lamp, but LEDs. LEDs emit light, and the DLP micromirror matrix forms an image. Since the matrix and LEDs are tiny, the device is compact and light in weight.
Advantages of the ultra-short throw LED projector:
- light weight and dimensions. There are low-power projectors the size of a pack of cigarettes;
- low power consumption, since LEDs consume 7-8 times less energy than lamps;
- long life of LEDs, 5-10 times longer than lamps.
The drawback is one and very important - a small luminous flux of not more than 2000 lumens, which implies its use only in dark rooms.
For home use, such a projector is quite suitable, but for business trips due to its miniature size and low weight, its use is very tempting.
Epson Projectors - Leaders in the Global Multimedia Industry
Epson ultra-short throw projectors are part of a large line of projectors from this Japanese corporation. Seiko Epson was the first company in the world to launch the device in 1989. Since 2001, she has been a permanent leader in this industry. She has the widest range of projectors among competitors for any tasks and different price categories. Epson ultra short throw projectors in education are used to create interactive classes in higher and secondary educational institutions. And in this segment, Epson is a trendsetter and innovation leader.
The modern line of ultra short-throw projectors Epson includes the following models: Epson EB-595Wi, EB-675W, EB-675Wi, EB-680W, EB-680Wi, EB-696Ui and others. Since these projectors are used in education, i.e., as a rule, in bright rooms, one of the requirements is the brightness of the light flux. All presented models are very powerful: 3200-3500 lumens.
The younger model Epson EB-595Wi has the following main characteristics:
- a very short projection distance (44 cm) on the screen - 190 cm;
- high contrast - 14,000: 1;
- brightness of a light stream - 3200 lumens;
- very high lamp life - 10,000 hours;
- WXGA resolution (1280x800);
- interactive image on any surface.
By marking the model, you can find out some of its characteristics. For example, the letter i indicates that this model is interactive, the letter W is the resolution of WXGA (1280x800), U is WUXGA (1920x1200).
LG projectors are the best among gaming and home models
LG needs no introduction. Among all the variety of equipment offered by the company in the world market, LG ultra-short throw projectors stand out. The company is not a world leader in the production of these devices, like Epson Corporation. But she has taken the lead in the segment of home and gaming devices, as well as in the market for LED projectors. One of the novelties, the model of this segment is the ultra-short focus projector LG PH450UG-GL.
An amazing model has the following characteristics:
- from a distance of 33 cm, an image of 2 meters is formed;
- wireless connection - video is transmitted via Wi-Fi, sound - via Bluetooth, 2.5 hours you can work with batteries;
- weight - 1.1 kg;
- brightness - 450 lumens.
Full HD - a necessary standard for projector image quality
Projectors used at home as home cinemas should display high-quality content, and such in the coming years will be the Full HD standard with a resolution of 1920 × 1080 pixels. In this regard, Full HD ultra short throw projectors began to enter the market, although the price is still high. Among the released models are the following projectors - the LG PH450UG-GL, LG PH1000U, Optoma EH319UST, Optoma EH320UST, Epson EH-LS100, etc. listed in the article above. The listed models are different in price, characteristics, and image acquisition method. LG - the cheapest LED projectors , they are low-power, inexpensive (a little more than 40 000 rubles), but at home, where you can reduce the illumination of the room, they will quite suit the audience. Optoma of the middle price category, lamp, quite powerful 3000 lm, the price is 120 000-150 000 rubles. And finally, Epson - the most expensive model - 250 000 rubles, laser, very powerful, with a brightness of 4000 lm. All the projectors presented, especially the last one, are a real alternative to huge televisions, and, according to experts and users, there is a future for such devices.