Twelve-constellation projector model _ constellation projector

Source: Zhihu.

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First of all, it needs to be declared that this paper aims to popularize the concept of projector for beginners, so we only need to understand some basic concepts in combination with the latest market and technical conditions, so that everyone can know fairly well when purchasing.

This is a standard home theater.

Projector is the most important core of building a home theater. The basic principle is not complicated, that is, the projector first irradiates light on the image display element to produce an image, and then projects it through the lens. In the home theater, the visual stimulation of the whole big picture depends on the projector. Maybe you will say that a large-screen LCD TV can also build a home theater. Theoretically, of course. But projection is still the most cost-effective way to realize large screen.

This is how hundreds of inches of TV sets enter the home.

Compared with the screen size of 120 inch or even higher, which is often projected by home projector, the TV screen size of 50-60 inch is too small, while the LCD screen above 100 inch is either too expensive or too large and takes up space. Therefore, the projector is the only way to create a satisfactory home theater.

What's the difference between commercial projectors and home projector?

The commercial machine is mentioned here first, mainly because many people's cognition of projectors actually started from commercial projectors, not from home projectors. After all, many halls and clubs have installed projectors now, so there are more opportunities for everyone to contact. However, due to the different positioning and application environments of commercial computers and home computers, the performance is very different, which also makes many people have a lot of wrong understanding of home projectors.

Projectors in commercial situations often do this, and there are worse pictures.

First of all, the lumen of a commercial machine is higher than that of a household machine (lumen is the unit of luminous flux, which refers to the total amount of light emitted by a light source in a certain unit time), because the environment of commercial occasions is very bright, and if the projector is not bright enough, it is easy to see clearly, but after the brightness is too high, the picture will be white and distorted. When watching * * at home, you can turn off the lights and draw the curtains or do it in a separate space. If there is no interference from sunlight or lights, the problem is not obvious.

On the other hand, the contrast of commercial computers is much worse than that of home computers. To put it simply, on the screen of home projector, reddish, pink, crimson and purplish red can be distinguished, which is a color transition, but on the commercial machine, the area with small color difference is directly a whole color.

Finally, the picture scale and resolution. A narrow picture ratio of 4: 3 is still very common in business situations. Although many commercial machines also support widescreen, the resolution is generally 720P, and only a few high-end commercial machines support 1080P. But home projector is full of 16: 9 widescreen images. The resolution of mainstream models has popularized full HD 1080P, and it is moving towards finer 4K. At present, only a few low-end machines are 720P p.

Therefore, in general, commercial machines are mainly used for PPT demonstrations and other exhibitions, and are used for work. The focus is not on indicators that are more important to * *, such as image quality and color. Sometimes, in some shopping malls, cafes, restaurants and other places, you can often see some projectors. I have observed that most of these projectors are low-end commercial machines, and the main reason why merchants buy them is that they are cheap, but the effect is not the key. I hope that home theater users will not be misled by commercial projectors that only look similar.

How big is the room where the projector is used?

Because of the principle of projection, the projector needs a certain distance to project a big picture, so the place where you install the projector in your room needs to keep a certain distance from the curtains. The projection distance of each projector varies with different lens parameters, but in most cases, a large picture of 100~ 120 inch can be projected about 4 meters. But here's the problem. What if there is no such distance at home for various reasons?

This requires the use of ultra-short focus projectors. The distance between the lens and the curtain of this machine is only a few tens of centimeters, which can project a large picture, but the price of the ultra-short focus projector is slightly higher. Moreover, some manufacturers use the characteristics that the ultra-short focus camera can be projected on the TV cabinet to package it into the concept of "TV", such as screen-free TV, giant screen TV and so on, but these are all concept games and are essentially home projectors.

Is projector bulb life a problem?

Because of the working principle of projector, a light source is needed inside the machine. For a long time, projectors mainly use halogen bulbs or mercury lamps. At present, the life of projector bulbs on the market is usually around 2000 ~ 5000 hours. After using them for a period of time, their brightness will decrease obviously, and the quality of the projected picture will also deteriorate. At this point, the user needs to replace the light bulb of the projector.

But is this question really important? Take the life span of at least 2000 hours as an example. If one * * counts as two hours, you can watch 1000 * * in 2000 hours, and you have to watch one * * every day for nearly three years. In fact, this is absolutely impossible, so it can be used for at least four or five years, and then you may have to change planes.

So most people don't need this life span. However, in order to eliminate the user's panic, some manufacturers promise to provide double light service, that is, to give you a spare light bulb, but this light bulb will not be provided to you until the built-in light bulb of the machine is damaged. As far as I know, few people will take advantage of this opportunity, so manufacturers are not stupid, just use this marketing strategy to dispel your fear of light bulb life. It's like the lithium battery in your mobile phone has a long life, but in fact, it is rarely replaced because of normal use, and most of them have quality problems.

On the other hand, technology is also progressing, and new light sources with long life such as LED and laser are gradually entering the projector. However, at present, the new light source technology is still in the process of popularization, and the new light source machine that can achieve the performance of mainstream projectors is expensive, while some entry-level machines with LED concept have poor performance indicators such as brightness and contrast.

Can I buy a 2XXX LED projector on a treasure?

Don't trust the LED projection of various cottage brands on a treasure. The advertisement is blown up, and the effect of "real shooting" is almost catching up with the big-name high-end flagship, but what is the actual effect? You can go to some related forums to see the real list of netizens who spend money on classes. These low-end brand-name LED projectors are always boasting about their advantages over traditional bulb light sources in terms of long life (LEDs generally last for 20,000 to 50,000 hours). But in fact, they use led, because such a cheap machine can hardly make any money with high-cost light bulbs, and cheap led is easy to buy in those places in Shenzhen, so they can make a profit.

Some low-cost projectors like to play with word concepts, such as writing compatible 1080P and 4K, but actually compatible means that you can play 1080P or 4K movies, but the resolution it shows you is only 720P.

But it doesn't mean that those two or three thousand LED projectors are knockoffs, or there are some well-known brands, but they are limited by the technical performance of the kernel and can't meet the needs of mainstream HD home theater users, mainly for young people who are still renting houses. This kind of people are more concerned with solving problems, and whether the effect is excellent or not is not the key. So there is nothing wrong with low-end products. We are not averse to honesty. What I resist is the products with unqualified quality, serious false standards of various parameters and false propaganda.

What do 3 3 LCD and DLP mean?

Finally, a little technical content. It doesn't matter if you don't understand. Finally, we have a summary. When reading all kinds of home projector advertisements and parameter lists, you can often see words such as 3LCD and DLP. These are actually the technical classification of projectors, that is, the technical way they realize projection.

There are three mainstream home projection technologies: 3LCD, DLP and LCOS.

3 LCD:

Red, green and blue liquid crystal panels are used as the control layers of red, green and blue light respectively. The white light emitted by the light source is converged to the beam splitter through the lens group, and the red, green and blue light are separated and projected onto the independent liquid crystal panel respectively. Corresponding pixels on the LCD panel receive electrical signals from signal sources, display different transparency, and generate images with different transparency for each pixel. Three monochromatic images converge in a prism and are projected onto a projection screen by a projection lens to form a full-color image.

DLP:

The full name of DLP is digital optical processing, which means "digital optical processing technology" in Chinese. DMD, the core component of DLP projector, is called digital micromirror device, which means "digital micromirror device" in Chinese, and displays images by controlling the deflection of lens.

lco:

The basic principle of LCOS (Liquid Crystal on Silicon) projector is similar to that of LCD projector, except that LCOS projector uses LCOS panel to control light projection. LCOS panel is based on CMOS chip as circuit substrate and reflective layer. Liquid crystal is injected between CMOS integrated circuit chip and transparent glass substrate. CMOS chips are used as mirrors after polishing. The light passes through the glass substrate and the liquid crystal material, and is reflected from the chip surface after darkening.

If you still don't understand the principles of the above three technologies, it doesn't matter. Generally speaking, each technology has its advantages and limitations. Compared with single DLP technology, 3LCD has better expressive power in color, but brightness and 3D effect are weak points. A single DLP is excellent in brightness, but its expressive force in color is weak. Low-end products are prone to rainbow phenomenon, and LCOS is balanced in all aspects, but it is expensive and bulky. However, technology belongs to technology, and it is easy to fall into unnecessary contrast without price and specific environment.

Every technology, in each manufacturer's products, will be improved and adjusted in different ways for complex comprehensive reasons such as price and positioning, so as to make products that meet the market demand. It is absolutely wrong to say that the products of one technology are better than others.

At present, 3LCD is mainly used by Japanese manufacturers such as Epson, and DLP is the technology of Texas Instruments. It does not produce its own projectors, but supplies them to other manufacturers, such as BenQ, Otto Code and other manufacturers in Taiwan Province Province, as well as American manufacturers such as Barco and DP, and Japanese manufacturers are mainly used by Sharp. LCOS is mainly used by JVC and Sony (Sony's LCOS technology is called SRXD) projectors, both of which are their own LCOS chips.