Choosing a Home Cinema Projector
From the projector in a home theater, first of all, you need a high-quality picture. We will tell in this material about how it is formed with the help of which components are influenced and how to choose the best option taking this information into account.
Speaking of a multimedia projector, we mean a device capable of reproducing an image, receiving a digital signal at the input. Sometimes the projector itself can play some types of files, but a detailed analysis of this functionality is beyond the scope of our review. In addition, since analog devices are almost out of the market, here we will focus only on digital projectors.
The projector forms an image using, relatively speaking, 4 components:
Each component contributes to the final result. To make an informed choice, you need to be aware of which component is responsible for what.
The source can be a halogen or other gas discharge lamp, as well as LEDs or lasers of three primary colors.
The source should give a large and uniform light output, so that the picture is bright, and at the same time have a reasonable service life. Halogen lamps give a fairly bright light output, but their service life is too small. In addition, such a lamp is heated, which leads to the rapid failure of neighboring components - first of all, the matrix. And for some types of discharge lamps characteristic degradation of power as exploitation.
Lamps are used in most models for home theaters of any price range, for example, in Acer V9800 or Canon LV-X320 .
Acer v9800
Canon LV-X320
There are many variations of halogen and gas discharge lamps, but they are united by a relatively short lifetime. With regard to home theaters, the service life should be taken into account in conjunction with the service of the manufacturer itself. In this segment, there are quite expensive models, and some manufacturers, such as Canon, are ready to provide replaceable lamps during the warranty period under certain conditions - at a minimum, register the device on the site.
Light-emitting diodes and lasers make it possible not to use light filters in the modulator and last longer than lamps. But LEDs often do not provide enough light, and lasers are expensive and difficult to configure for more or less natural color reproduction, therefore, in home theater devices are used much less frequently. For example, the LG family of models, in particular, LG PF1500G, works on them. More often LEDs and lasers are found in universal projectors or in expensive installation models.
There are solutions where LEDs and lasers complement each other, but their main drawback is the relatively high price.
Three technologically different types of modulators are common on the market:
As with light sources, each of the existing technologies has its own advantages and disadvantages. For example, DLP provides a higher image contrast than the closest competitor - LCD. On the other hand, with a quick change of the image, DLP image artifacts appear. LCoS combines the advantages of both LCD and DLP, although it has a high price.
To obtain a color image in the projector, one or more modulators are used. If the modulator is one, it is illuminated by a luminous flux, which in turn passes through different light filters. To do this, a rotating disk is installed on the path of the luminous flux, the sectors of which are filters of different colors. So alternately red, green and blue images are created, which due to the inertia of view are mixed for the viewer in one color. Sometimes transparent is added to the three main filters, which helps to increase the contrast, to the detriment of saturation.
The device in this case is more expensive, but on the moving images there is no noticeable flicker and the so-called rainbow effect. In addition, the picture on such projectors will be brighter (with the same power of the light source). Designs with three modulators can use not one, but three sources of different colors (instead of a system of mirrors, prisms and light filters), which allows to further increase the brightness of the image.
Obviously, projectors with three modulators, other things being equal, are more expensive and more massive. At the same time, they are subject to higher requirements for assembly accuracy, since the light fluxes passing in different ways should be formed into a clear picture.
The technologies described above are rather difficult to line up according to formal characteristics, since the subjective impression of the picture is determined by other components of the projector. Manufacturers either choose a more advanced light source technology and a modulator, or they invest in related technical solutions to compensate for many of the shortcomings of simple approaches in a specific use case. So in comparison, we must always take into account the specific models and tasks.
In the segment of home theater projectors, either one DLP matrix or three LCD matrixes are most often used. At the same time, the price of the projector is practically independent of technology.
Examples of using a single DLP matrix: NEC NP-V332XG or Panasonic PT-AE8000EA .
NEC NP-V332XG
Another option is three LCD matrices: Epson EH-TW550 or Panasonic PT-LB332E .
Epson EH-TW550
Panasonic PT-LB332E
For comparison, an example using Sony's patented SXRD technology is Sony VPL-HW45 .
The light modulator is the element that determines the resolution of the image on the screen. The most popular now is FullHD (1920x1080). There are extremely expensive 4K projectors; 4K comes to this segment with some delay regarding the TV market. At the same time, even among the various “TOP-10” of this year, there are a lot of devices, even without FullHD support. More often they belong to the lowest price range. A good example is the Canon LV-X320 .
FullHD permission in most cases is sufficient for residential premises. The picture below explains when it’s not worth overpaying for pixels:
Recommended screen size depending on the viewing distance.
Vertical - viewing distance, horizontally - the size of the screen. The plane is divided into sectors corresponding to different resolutions of the picture. The boundaries of these zones represent the distance at which for a given screen diagonal the subjective difference between the higher and lower resolution pictures disappears.
When studying this picture we recommend to rely on the idea of viewing angles of the screen. TVs are usually recommended to be installed so that the viewing angle is about 35 degrees (this means that the distance to the screen is about 3 times its diagonal). For comparison: in the IMAX cinema the viewing angle is 60-120 degrees horizontally and 40-80 degrees vertically (depending on the place in the hall).
After talking about pixels and angles, we move on to another component of the projector, optics. Its task is to provide maximum viewing angle without image distortion. In the most clear interpretation - a larger viewing angle allows you to get a larger diagonal of the image with a smaller removal of the projector. However, it is worth remembering that a larger image size means a larger pixel size, which brings us back to the resolution discussion.
Like photo lenses, the optics of the projectors differ in focal length, which determines the ratio of the projection (how large an image can be obtained from such a distance or how far a projector should be placed to obtain an image of a given diagonal). The more focus, the less chance of getting distorted images. On the other hand, the smaller the focus, the closer to the screen the projector can be positioned (and in rooms the installation distance of the projector is in any case limited by the walls).
As the parameters characterizing the optics, the minimum / maximum distance to the screen with the minimum / maximum diagonal is often indicated (if only one group of values is indicated, then the ratio of the viewing distance to the diagonal of the image is usually added to them). For example, on Yandex.Market, the description of the BenQ W1050 model includes the following data:
By analogy with cameras, the optics of projectors can be interchangeable, but more often such models belong to the segment of installation devices.
The task of electronics is to control all the components listed above in order to obtain, in manual or automatic mode (depending on the declared functions of the device) a clear image on the screen. In particular, electronics compensates for optical image distortion. Some devices even have special tools to automatically compensate for distortion (for example, Screen Fit for Epson).
Above, we talked a lot about the imperfection of the technologies used in modern projectors for imaging (and in fact there are many more). Electronics can partially compensate them. With the help of aperture control, you can get a more pronounced black color for LCD projectors or reduce the rainbow effect for DLP - as in Acer AcuMotion , which generates intermediate frames in rapidly changing scenes to create a smoother motion. Also, electronics help to optimally use the lamp life - such as in Benq's LampSave technology, which dynamically controls the brightness to increase service life.
Also, electronics is responsible for the formation of 3D. The overwhelming majority of home projectors use technology of active glasses synchronized with the projector. Now the technology of imaging for different eyes with the help of different parts of the spectrum, allowing not to use a special screen. But the absence of a large amount of 3D content, the very need to wear glasses and the subjective decrease in the brightness of the 3D image (due to losses during filtration by glasses) play against the spread of this technology. Despite this, there are quite a lot of 3D models on the market.
Above, we conditionally divided the projector into components. The technologies used in them not only offer advantages, but also create limitations, the struggle with which creates various engineering difficulties - the need for noisy cooling, dust, parasitic reflections of light, etc. As a result, the development of projectors rests not only in the search for new ideas, but also in the constant struggle with shortcomings.
And the components can influence each other: you can not just put together an arbitrary light source, some kind of imaging technology and one of the ways to create colors. In this case, the shortcomings of each of the approaches can reinforce each other and the device will not be competitive. So, speaking about the minimization of problems, we mean the work on the entire device in the complex.
It is reasonable to include the screen in the list of elements determining the subjective image quality at the output. The geometry and coverage of the screen, as well as the illumination of the room where it is installed, inevitably affect the perception of the picture.
For example, the farther from the projector the screen is, the larger the image itself at the same viewing angle. But it is perceived less bright (the luminous flux per unit area decreases). And the brighter the ambient light, the brighter you need a projector for the same tasks.
The screen is usually purchased separately and can be selected under certain requirements. Usually, geometry is taken into account, the method of installation (wall or ceiling fasteners are relevant for the house; a tripod or floor installation in everyday life is less convenient), the presence of an automatic drive that folds the screen, as well as a floor. The last factor is perhaps the most important because it allows not losing the brightness and contrast of the image due to incomplete reflection. However, the characteristics of coatings - a topic for another conversation.
Before making the final choice, you need to decide on a budget and answer questions about the intended use case.
If the projector will act as a universal replacement for the TV (work in the background, games, watching movies), we need a “long-playing combine”. Here you can not pay special attention to the subtleties of color and contrast, since in such conditions they simply do not appear. As a result, the choice is likely to fall on the 3LCD model.
If we need a full-fledged home theater (lights off, requirements for picture quality), i.e. we focus on the beauty of color (accurate color, true black) to the detriment of brightness - we look in the direction of DLP.
After that, the parameters of the room and the available places for mounting the projector are used - this information will give us the required optics parameters (or the desired distance to the screen / diagonal).
Speaking of a multimedia projector, we mean a device capable of reproducing an image, receiving a digital signal at the input. Sometimes the projector itself can play some types of files, but a detailed analysis of this functionality is beyond the scope of our review. In addition, since analog devices are almost out of the market, here we will focus only on digital projectors.
The projector forms an image using, relatively speaking, 4 components:
- light source;
- “Modulator”, thanks to which we see not just the light of the lamp, but a color picture;
- optics, allowing to focus the image on the screen;
- electronics that manages all of this.
Each component contributes to the final result. To make an informed choice, you need to be aware of which component is responsible for what.
Light source
The source can be a halogen or other gas discharge lamp, as well as LEDs or lasers of three primary colors.
The source should give a large and uniform light output, so that the picture is bright, and at the same time have a reasonable service life. Halogen lamps give a fairly bright light output, but their service life is too small. In addition, such a lamp is heated, which leads to the rapid failure of neighboring components - first of all, the matrix. And for some types of discharge lamps characteristic degradation of power as exploitation.
Lamps are used in most models for home theaters of any price range, for example, in Acer V9800 or Canon LV-X320 .
There are many variations of halogen and gas discharge lamps, but they are united by a relatively short lifetime. With regard to home theaters, the service life should be taken into account in conjunction with the service of the manufacturer itself. In this segment, there are quite expensive models, and some manufacturers, such as Canon, are ready to provide replaceable lamps during the warranty period under certain conditions - at a minimum, register the device on the site.
Light-emitting diodes and lasers make it possible not to use light filters in the modulator and last longer than lamps. But LEDs often do not provide enough light, and lasers are expensive and difficult to configure for more or less natural color reproduction, therefore, in home theater devices are used much less frequently. For example, the LG family of models, in particular, LG PF1500G, works on them. More often LEDs and lasers are found in universal projectors or in expensive installation models.
There are solutions where LEDs and lasers complement each other, but their main drawback is the relatively high price.
Light modulator
Three technologically different types of modulators are common on the market:
- translucent liquid crystal matrix (LCD) - one or more in the device;
- an array of microscopic guided mirrors on a chip that can be fixed in one of two positions (DLP - Digital Light Processing) - also one or several;
- LCOS reflecting LCD matrix (Sony version - SXRD; three-chip version from JVC - D-ILA), more resistant to powerful light emission;
As with light sources, each of the existing technologies has its own advantages and disadvantages. For example, DLP provides a higher image contrast than the closest competitor - LCD. On the other hand, with a quick change of the image, DLP image artifacts appear. LCoS combines the advantages of both LCD and DLP, although it has a high price.
To obtain a color image in the projector, one or more modulators are used. If the modulator is one, it is illuminated by a luminous flux, which in turn passes through different light filters. To do this, a rotating disk is installed on the path of the luminous flux, the sectors of which are filters of different colors. So alternately red, green and blue images are created, which due to the inertia of view are mixed for the viewer in one color. Sometimes transparent is added to the three main filters, which helps to increase the contrast, to the detriment of saturation.
The device in this case is more expensive, but on the moving images there is no noticeable flicker and the so-called rainbow effect. In addition, the picture on such projectors will be brighter (with the same power of the light source). Designs with three modulators can use not one, but three sources of different colors (instead of a system of mirrors, prisms and light filters), which allows to further increase the brightness of the image.
Obviously, projectors with three modulators, other things being equal, are more expensive and more massive. At the same time, they are subject to higher requirements for assembly accuracy, since the light fluxes passing in different ways should be formed into a clear picture.
The technologies described above are rather difficult to line up according to formal characteristics, since the subjective impression of the picture is determined by other components of the projector. Manufacturers either choose a more advanced light source technology and a modulator, or they invest in related technical solutions to compensate for many of the shortcomings of simple approaches in a specific use case. So in comparison, we must always take into account the specific models and tasks.
In the segment of home theater projectors, either one DLP matrix or three LCD matrixes are most often used. At the same time, the price of the projector is practically independent of technology.
Examples of using a single DLP matrix: NEC NP-V332XG or Panasonic PT-AE8000EA .
Another option is three LCD matrices: Epson EH-TW550 or Panasonic PT-LB332E .
For comparison, an example using Sony's patented SXRD technology is Sony VPL-HW45 .
The light modulator is the element that determines the resolution of the image on the screen. The most popular now is FullHD (1920x1080). There are extremely expensive 4K projectors; 4K comes to this segment with some delay regarding the TV market. At the same time, even among the various “TOP-10” of this year, there are a lot of devices, even without FullHD support. More often they belong to the lowest price range. A good example is the Canon LV-X320 .
FullHD permission in most cases is sufficient for residential premises. The picture below explains when it’s not worth overpaying for pixels:
Recommended screen size depending on the viewing distance.
Vertical - viewing distance, horizontally - the size of the screen. The plane is divided into sectors corresponding to different resolutions of the picture. The boundaries of these zones represent the distance at which for a given screen diagonal the subjective difference between the higher and lower resolution pictures disappears.
When studying this picture we recommend to rely on the idea of viewing angles of the screen. TVs are usually recommended to be installed so that the viewing angle is about 35 degrees (this means that the distance to the screen is about 3 times its diagonal). For comparison: in the IMAX cinema the viewing angle is 60-120 degrees horizontally and 40-80 degrees vertically (depending on the place in the hall).
Optics
After talking about pixels and angles, we move on to another component of the projector, optics. Its task is to provide maximum viewing angle without image distortion. In the most clear interpretation - a larger viewing angle allows you to get a larger diagonal of the image with a smaller removal of the projector. However, it is worth remembering that a larger image size means a larger pixel size, which brings us back to the resolution discussion.
Like photo lenses, the optics of the projectors differ in focal length, which determines the ratio of the projection (how large an image can be obtained from such a distance or how far a projector should be placed to obtain an image of a given diagonal). The more focus, the less chance of getting distorted images. On the other hand, the smaller the focus, the closer to the screen the projector can be positioned (and in rooms the installation distance of the projector is in any case limited by the walls).
As the parameters characterizing the optics, the minimum / maximum distance to the screen with the minimum / maximum diagonal is often indicated (if only one group of values is indicated, then the ratio of the viewing distance to the diagonal of the image is usually added to them). For example, on Yandex.Market, the description of the BenQ W1050 model includes the following data:
By analogy with cameras, the optics of projectors can be interchangeable, but more often such models belong to the segment of installation devices.
Electronics
The task of electronics is to control all the components listed above in order to obtain, in manual or automatic mode (depending on the declared functions of the device) a clear image on the screen. In particular, electronics compensates for optical image distortion. Some devices even have special tools to automatically compensate for distortion (for example, Screen Fit for Epson).
Above, we talked a lot about the imperfection of the technologies used in modern projectors for imaging (and in fact there are many more). Electronics can partially compensate them. With the help of aperture control, you can get a more pronounced black color for LCD projectors or reduce the rainbow effect for DLP - as in Acer AcuMotion , which generates intermediate frames in rapidly changing scenes to create a smoother motion. Also, electronics help to optimally use the lamp life - such as in Benq's LampSave technology, which dynamically controls the brightness to increase service life.
Also, electronics is responsible for the formation of 3D. The overwhelming majority of home projectors use technology of active glasses synchronized with the projector. Now the technology of imaging for different eyes with the help of different parts of the spectrum, allowing not to use a special screen. But the absence of a large amount of 3D content, the very need to wear glasses and the subjective decrease in the brightness of the 3D image (due to losses during filtration by glasses) play against the spread of this technology. Despite this, there are quite a lot of 3D models on the market.
Above, we conditionally divided the projector into components. The technologies used in them not only offer advantages, but also create limitations, the struggle with which creates various engineering difficulties - the need for noisy cooling, dust, parasitic reflections of light, etc. As a result, the development of projectors rests not only in the search for new ideas, but also in the constant struggle with shortcomings.
And the components can influence each other: you can not just put together an arbitrary light source, some kind of imaging technology and one of the ways to create colors. In this case, the shortcomings of each of the approaches can reinforce each other and the device will not be competitive. So, speaking about the minimization of problems, we mean the work on the entire device in the complex.
Screen and light
It is reasonable to include the screen in the list of elements determining the subjective image quality at the output. The geometry and coverage of the screen, as well as the illumination of the room where it is installed, inevitably affect the perception of the picture.
For example, the farther from the projector the screen is, the larger the image itself at the same viewing angle. But it is perceived less bright (the luminous flux per unit area decreases). And the brighter the ambient light, the brighter you need a projector for the same tasks.
The screen is usually purchased separately and can be selected under certain requirements. Usually, geometry is taken into account, the method of installation (wall or ceiling fasteners are relevant for the house; a tripod or floor installation in everyday life is less convenient), the presence of an automatic drive that folds the screen, as well as a floor. The last factor is perhaps the most important because it allows not losing the brightness and contrast of the image due to incomplete reflection. However, the characteristics of coatings - a topic for another conversation.
What to choose: ask the right questions
Before making the final choice, you need to decide on a budget and answer questions about the intended use case.
If the projector will act as a universal replacement for the TV (work in the background, games, watching movies), we need a “long-playing combine”. Here you can not pay special attention to the subtleties of color and contrast, since in such conditions they simply do not appear. As a result, the choice is likely to fall on the 3LCD model.
If we need a full-fledged home theater (lights off, requirements for picture quality), i.e. we focus on the beauty of color (accurate color, true black) to the detriment of brightness - we look in the direction of DLP.
After that, the parameters of the room and the available places for mounting the projector are used - this information will give us the required optics parameters (or the desired distance to the screen / diagonal).
Source: https://habr.com/ru/post/410221/