Brightness
The brightness of the image produced by the projector at maximum backlight brightness. Usually, the average brightness of the screen, derived from a special formula, is indicated. The higher it is, the less the image depends on ambient light: a bright projector can provide a clearly visible image even in daylight, but a dim one will require dimming. On the other hand, increasing brightness reduces contrast and accuracy of colour reproduction.
Accordingly, when choosing this parameter, you need to consider the conditions in which you plan to use the projector. So, for office or school/university use, a brightness of at least 3000 lm is desirable — this allows you to get normal visibility without obscuring the room. In turn, among the top models a very low brightness can be found, because. such projectors are usually installed in rooms specially designed for them with good darkness level. And in ultra-compact devices it is impossible to achieve high brightness for technical reasons.
Detailed recommendations on the optimal brightness for certain conditions can be found in special sources. Here we note that anyway, it is worth choosing according to this indicator with some margin. As mentioned above, as brightness increases, contrast and colour quality decrease, and you may need to use the projector at a reduced brightness to achieve the desired picture quality.
Brightness ANSI Lumens
This parameter largely determines the ability of the projector to work in a well-lit room. For a dark room, 1000 lumens is enough to make the projection picture bright, rich, clear and understandable. But when working in a lit room, the projector will need at least 3500-4000 lumens. Do not confuse ANSI lumens with Peak lumens. These are two different brightness standards. To convert one type of brightness to another, you need to multiply Peak lumens by 10-12. The result will be an approximate value of ANSI Lumens.
However, experts do not recommend chasing high ANSI lumen brightness values. There are many professional projectors with brightness up to 3500 lm. The lower the brightness, the lower the power consumption, and at the same time, the life of the illuminator increases. Of course, if the projector will be installed in a work office or classroom where good lighting is required, it is recommended to purchase a model with ANSI Lumens brightness of 4000 lumens and more.
Max. video resolution
The actual maximum frame resolution that the projector is capable of processing and displaying.
Many models allow project images at a higher resolution than the actual resolution of the projector matrix (see above). For example, a 1920x1080 video can be displayed on a device with a frame size of 1024x768. However, the quality of such an image will be noticeably lower than on a projector, which initially has a resolution of 1920x1080.
The maximum resolution is closely related to both the overall picture quality and the size of the projection screen. The higher the resolution, the sharper the image details become. Of course, the screen size itself should be taken into account. The fact is that on a 40-50″ projection surface there will not be much difference between the Quad HD and 4K formats. A high-resolution picture will be able to show itself on a truly large screen.
USB 2.0
The number of USB 2.0 ports provided by the projector.
Do not confuse these connectors with USB slave (see "Management ports") — in this case we are talking about
USB ports for various peripherals. Most often, these ports are used for direct playback of content from flash drives and other storages (for example, external HDDs). At the same time, we note that video viewing is not available in some projectors (only photos), in others a very limited set of formats may be supported. However, a direct connection is often more convenient than viewing through a computer or other device. The USB ports can also be used for other purposes, such as updating firmware, transferring files between a flash drive and the projector's built-in storage, or even for keyboards/mouses (in Android devices, see above).
The USB 2.0 standard itself is considered obsolete, but it is quite enough for projectors, and newer peripherals are fully compatible with such connectors. At the same time, you rarely have to connect more than one external device to the projector at a time, so there are few models with more than one USB 2.0.
Video connectors
Inputs for connecting external video sources provided in the projector.
— VGA. Analogue video interface, that considered obsolete, but still quite popular; VGA outputs are found in video technology, as well as in some computer graphics cards. It supports resolutions up to 1280x1024, which allows you to work with 720p video, but more advanced HD standards are out of the question. Audio signal transmission via VGA is not provided, the soundtrack for such a video will have to be connected separately.
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DVI. A video interface primarily used to connect projectors to computers. Initially, it did not provide sound transmission, but this possibility is gradually being introduced. Nowadays, several varieties of DVI are used. So, according to the signal format, purely digital DVI-D and combined DVI-I, which supports digital and analogue video, are distinguished. In both of these varieties, a two-channel digital data transmission format can be used, in which the maximum video resolution reaches 2560x1600 (in single-channel it is 1920x1200). Connectors and plugs DVI-D and DVI-I are compatible with each other if the number of channels matches, or if a single-channel video signal is connected to a two-channel input.
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DisplayPort. A digital interface originally designed for connecting LCD monitors. Modern versions are similar in capabilities to HDMI, they support HD resolutions of 1080p an
...d higher, as well as multi-channel audio transmission. However, such outputs are rare in video devices; the main area of application for DisplayPort has been and remains computer technology. In particular, it is this connector (as well as its reduced version miniDisplayPort) that Apple regularly uses in its computers.
- — DisplayPort v 1.2. DisplayPort v 1.2 has a bandwidth of 17.28 Gbps. This signal transmission standard has full support for FullHD video format. QuadHD and 4K formats are partially supported.
- Display Port v 1.3. The maximum bandwidth of DisplayPort v 1.3 is 25.92 Gbps. This version of DisplayPort provides full support for FullHD and QuadHD formats. 4K and 8K video modes are partially supported.
- Display Port v 1.4. The bandwidth limit of DisplayPort v 1.4 is 32.4 Gbps. This version of DisplayPort features enhanced support for 4K video, including 144Hz refresh rates, while DisplayPort 1.3 only limits 4K to 120Hz. Like the previous version, DisplayPort 1.4 partially supports 8K video modes.
— BNC. Bayonet type connector used to connect coaxial cable. Projectors use this connection to transmit analogue component video (see the relevant paragraph) or uncompressed SDI video. BNC refers to professional interfaces and is found in projectors of the corresponding class.
— S-Video. Analogue interface for video transmission (without work with audio). Provides two channels for transmitting image information, similar to the component input described below. However, on the one hand, S-Video uses only one connector instead of three, on the other hand, the bandwidth of this interface is noticeably lower, it is not suitable for HD resolutions, in light of which it is considered obsolete and is rare, mainly found in specialized video equipment.
— Composite. Initially, a composite interface is called an analogue interface for transmitting video and sound, using 3 separate channels (for the video signal and the left and right audio channels). However, in this case, most often only one connector is meant — for video; audio inputs on projectors are listed separately and are referred to as RCA (audio) (see "Audio connectors"). In general, the composite interface does not have a high picture quality, besides it is not suitable for transmitting an HD image and is considered obsolete. On the other hand, it is very common and is found not only in modern video equipment, but also in outdated ones; for example, you can connect a VHS-VCR to the projector through this interface.
— Component. An interface that is considered the most advanced among modern analogue video standards. The video signal with this connection is divided into three components transmitted over separate cables; this provides good interference resistance and sufficient bandwidth even for HD resolutions. But the sound in this interface is not supported.HDMI inputs
The number of HDMI inputs provided by the projector.
HDMI is a comprehensive digital interface originally designed for high-definition video and multi-channel audio. Today, it is actually a generally accepted standard, outputs of this type are available in the vast majority of HD-enabled video devices — media centers, Blu-ray players, computer graphics cards, etc. The presence of several HDMI inputs allows you to simultaneously connect several signal sources to the projector and switch between them in the projector settings without having to connect and disconnect cables.
HDMI version
HDMI interface version supported by the projector.
About the interface itself, see above, and its different versions differ in maximum resolution and other features:
— v 1.4. The version released back in 2009. Despite this, it has quite decent specifications, due to which it continues to be used in modern video equipment. Specific features of HDMI v1.4 include 3D support, the ability to work with 4K video (4096x2160) at 24 fps and with Full HD at 120 fps. In addition to the original version, there are also improved modifications — v.1.4a and v.1.4b; they differ only in some 3D-related improvements.
– v 2.0. Standard introduced in 2014. Thanks to the increased bandwidth compared to v 1.4, it allows you to transfer 4K video at speeds up to 60 fps, as well as up to 32 channels and up to 4 audio streams simultaneously. In addition, this version was the first to introduce support for the 21:9 ultra-wide format, and the v2.0a update introduced HDR compatibility, with further enhancements to this feature in version 2.0b.
— v 2.1. A version released in 2017 also known as HDMI Ultra High Speed. The data transfer rate has indeed been significantly increased, allowing the support for video up to 10K at 120 frames per second. In addition, some improvements regarding HDR have been made. Note that connecting via HDMI v2.1 requires the use of special cables, although the basic features remain available when working with standard cables.
Audio connectors
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RCA (audio). Analogue audio interface using RCA jacks. Depending on the model of the projector, it can serve as both an input (for example, in addition to the component video input) and an output for connecting external audio devices. We only note that in this case only one channel of sound is transmitted through one RCA connector, and a pair of “tulips” (for the left and right channel) is considered an input or output.
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3.5 mm input (mini-Jack). This connector is more compact than RCA, in addition, it allows to work with two stereo channels through one jack. On the other hand, a 3.5 mm connection is less reliable and more prone to interference. Therefore, such an input is designed mainly for simple tasks — such as transmitting sound from the audio output of a PC or laptop.
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3.5 mm output (mini-Jack). This in any case is an analogue output, however, its specific purpose may be different. So, in some projectors it plays the role of a linear interface and is used to output an audio signal to active sound system or an external amplifier. In other devices, the mini-Jack works as a headphone output. There are models where these functions are combined in one connector.
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Optical output. An output for transmission of a digital audio signal by a fibre optic cable; allows the transmission of multi-channel audio. Not
...able for its complete insensitivity to electromagnetic interference. On the other hand, fibre optic cable is quite fragile, it must be protected from bending and strong pressure.
— Microphone input. Input for connecting an external microphone to the projector. Using it, you can stream sound from a microphone using the projector's own amplifier — for example, comment on a presentation through the same speakers through which the main sound goes.Service connectors
Service connectors for connecting control equipment, provided in the design of the projector. Specific control options in each case may be different, they should be specified separately.
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COM(RS-232). A specialized connector, originally used in computer technology. In general, it is considered obsolete, it is relatively rare among computers, but it is very popular in various specialized equipment.
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USB (slave). Connector for connecting to the USB port of a PC or laptop. With this connection, the projector acts as a peripheral device and can be controlled from a computer. In addition, relatively recently, portable projectors have appeared that are designed for wired connection to mobile gadgets such as smartphones or tablets; they also indicate the USB port (slave), although the specific connection may be different (for example, 8-pin in Apple devices).
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LAN (RJ45). Standard connector for wired connection to computer networks. A projector connected in this way works as a network device, it can be accessed (with appropriate settings) from any local computer. This can be more convenient than using only one control computer. In addition, other features can be implemented through the LAN — for example, DLNA (see the relevant paragraph).
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HDBaseT. A complex interface used mainly in professional equipme
...nt (see "Main purpose"). In fact, it is an extended version of the LAN described above, it uses the same connectors and cables, but it has more extensive functionality. In addition to LAN and Internet access, HDBaseT provides dedicated control signals, audio and video streaming, and even power up to 100 W.
— 3D Sync. This port allows you to connect a 3D emitter to the projector, which is necessary for the formation of a volumetric image using active 3D technology (see the relevant paragraph). Accordingly, in order to view a stereo image, it is necessary to use active-type 3D glasses. The glasses are synchronized with the 3D emitter, which makes it possible to achieve a clear and understandable stereo image.