Comparison Acer X127H vs Acer X115H

The main function of the projector.

This parameter is rather conditional, it largely depends on how the device is positioned by the manufacturer; however, for the most comfortable use, it is best to follow exactly the stated purpose. The options here can be: multipurpose, for presentations, for home theater, professional, portable, gaming. Here is a more detailed description of each option:

— Multipurpose. The simplest kind of projectors, roughly speaking – all models that do not belong to any of the specializations described below. Most of them have non-interchangeable optics, a throw distance of 1-12 m, an image diagonal of about 1-7 m (see below), and a relatively low cost.

— For presentations. Projectors designed primarily for business use, such as presentations. Usually they have a small throw distance with a rather large diagonal, which allows them to be used in small rooms; capable of working with both widescreen and conventional image formats (see below), and also support resolutions typical for computer graphics cards — for example, 1280x800. In this case, the actual resolution itself (see below) can be quite low. In addition, an almost mandatory feature of this type of projectors (with a few exceptions) is the presence of a D-Sub 15 pin input (see "Connectors").

— For home theater. Projectors designed primarily for film viewing. The main criterion for classifying a particular model in this category is how the projector is positioned by the manufacturer itself (in other words, whether this purpose is indicated in the official documentation). However, there are some common features: cinematographic models usually support widescreen image formats, have a high real resolution (see below) that allows you to work with HD video, and are also equipped with the appropriate interfaces (see "Connectors").

— Professional. High-quality projectors with advanced parameters, an abundance of functions and, accordingly, a considerable price. They are characterized by high image contrast, support high-resolution video (including cinematic image formats), have optical zoom to scale the image without losing quality, provide the connection of multi-channel sound systems, and much more. The specific set of options in professional projectors may vary depending on the model, but in any case, these are the most charged devices with top-end characteristics.

— Portable projector. An ultra-compact variety of projectors: most models are pocket-sized. Such devices are intended primarily for improvised presentations. The format of work and power supply may be different. So, some models are made as separate devices with their own built-in storages and batteries (and sometimes even with a full-fledged mobile OS like Android on board). Others are similar in design to external cases or consoles and are put directly on the mobile phone during operation, using it as a source of signal and power. However, anyway, portable projectors, due to their small size, have rather low technical specifications — they have neither brightness nor high image contrast.. Battery life (in models with their own batteries) usually ranges from 40 minutes to one and a half hours. Also, this variety is characterized by cost-effective LED lamps (see below).

— Gaming. Specialized projectors designed for use in video games. Outwardly, they are often distinguished by a characteristic “aggressive” design, while the design can be done in the style of a certain line of gaming PCs or laptops. As for the specifications, they, in accordance with the name, are aimed primarily at providing a high-quality game "picture". To do this, projectors for this purpose provide, in particular, high real resolution (not lower than 1920x720, and more often 1920x1080 or more), colour reproduction at the level of 1 billion colours, support for frame rate (see below) up to 120 Hz, and also at least one HDMI input for receiving a digital signal from a computer graphics card. In addition, such models often provide support for 3D. The maximum image diagonal can reach 7.5 m or more; at the same time, ultra-wide-angle devices are also found in this category, capable of providing an image diagonal of about 3 m from a distance of about half a metre.

The lamp model that the projector is designed for. Most projectors come with lamps included, so this information is not needed for normal use. But when looking for a spare lamp or replacement, information about model can be very useful: finding a spare part by the exact name is much easier than by general data like the brand of the projector.

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.

The native resolution of the image produced by the projector matrix.

The minimum for modern projectors is actually the VGA standard, which assumes a resolution of 800x600 or close to it. The most limited of modern high-definition standards is HD (720); the classic size of such a frame is 1280x720, but projectors also have other options (up to 1920x720). A more advanced HD format is Full HD (1080), which also has several variations (the most popular is 1920x1080). And among high-end projectors there are models of Quad HD, Ultra HD (4K) and even Ultra HD (8K) standards.

In general, the higher the resolution, the clearer and more detailed image the projector can produce. On the other hand, this indicator directly affects the cost, and all the benefits of high resolution can only be appreciated if the reproduced content also corresponds to it. Note that modern projectors can work with higher resolutions than the “native” ones – for more details, see “Maximum video resolution”.

— Light sensor. A sensor that detects the level of ambient light. Most commonly used to automatically adjust the brightness of the projector to suit current conditions. So, in a darkened room, high brightness is not needed, but in daylight, on the contrary, you cannot do without it. You can also adjust the operating mode manually, but it is more convenient when the projector does it automatically.

— DLNA support. DLNA technology is designed to connect home electronics into a single network and exchange content in real time. One of its advantages is that DLNA devices are guaranteed to be compatible with each other regardless of model and manufacturer. In a projector, this feature can be used, for example, to view a movie on a large screen from a computer hard drive, or to display an Internet broadcast on this screen that was originally opened on a tablet. DLNA works on the basis of a standard local network, with a connection via LAN (see "Management ports") or Wi-Fi (see below).

— MHL support. The projector has HDMI inputs that support the MHL standard. This standard is used to transfer video and audio from mobile gadgets (via microUSB) to external devices. Accordingly, this feature is useful for those who plan to connect smartphones and other portable equipment to the projector. At the same time, an MHL gadget connected t...o a compatible HDMI port can also be charged in the process. Note that you can also output the MHL signal to a regular HDMI port, but this will require an adapter, and the charging function will not be available.

— Picture-in-picture. Ability to play two channels simultaneously on one screen: main and additional (in a separate small window). The sound is played only for the main channel. This mode allows, for example, to skip a break in a football match and not be late for the second half. Note that for this function to work, images must come from different sources — for example, from two different tuners, or from a tuner and an external device (DVD player, media centre, etc.).

— PJ-Link protocol. The projector supports the PJ-Link protocol. This is a service standard designed to control projectors over local networks (usually LAN or HDBaseT, see "Management port"). All PJ-Link-enabled equipment (projectors, controllers) is fully interoperable regardless of brand and manufacturer, making it much easier to build networks of multiple projectors and replace individual components in such networks.

— 3D support. Support for 3D implies the ability to reproduce three-dimensional stereoscopic images. A 3D image can be based on various technologies. Traditionally, active (see the relevant paragraph), passive (see the relevant paragraph) and hybrid 3D technologies are distinguished. Special glasses are required to view the three-dimensional image. In the case of active 3D, special shutters are built into the glasses, which operate from an independent power source. For passive and hybrid 3D, regular 3D glasses without battery power are sufficient.

— Active 3D. Active 3D technology is based on the principle of alternating flickering of the image. The flickering of the image on the screen is synchronized with the flickering of the lenses in the glasses, as a result, each eye receives a separate image, which makes the picture three-dimensional. The main advantage of active 3D is the ability to view images without reducing the original picture quality. You can look at the screen from any angle and from any position, while the image will still be three-dimensional. Among the shortcomings, there is the presence of some discomfort for the eyes, which occurs due to the regular flickering of lenses in glasses. Also, active 3D glasses may darken the original brightness of the image somewhat. Additionally, glasses of this type are very expensive.

— Passive 3D. Passive 3D provides the display of a double image. Passive 3D glasses use special lenses that cut off the duplicate image in such a way that each eye sees only the image intended for it, which creates the illusion of a three-dimensional image. The main advantage of passive 3D is that it does not tyre the eyes, which is typical for active flickering 3D. Passive 3D glasses are inexpensive.

— Interactive pen. The projector supports interactive pen technology. This technology allows you to actually turn the projected image into an interactive whiteboard: with a pen, you can draw, write and make notes directly on the projected image, which is especially useful during presentations and educational events. It is worth taking into account that the pens themselves and additional equipment for their work may not be included in the set.

— Multimedia (air mouse remote). Air mouse remote are devices that have a gyroscope, which allows you not only to switch menu items with the “↑”, “↓” buttons, but to use the remote control as a mouse. By directing it to the screen, a cursor will appear that moves in the direction of the remote control. This makes management easier and faster.

— Voice control. The projector's support for voice control allows you to dictate certain commands through the remote control. However, voice control does not cover all functions and recognition accuracy may require re-entering the command. If you need a more extensive range of functions, then pay attention to the voice assistant.

— Voice assistant. For a long time now, device control has been shifting to voice commands. For this, certain interfaces and systems are used. The most popular are Amazon Alexa and Google Assistant. For "apple" devices, this is Apple Siri, but this technique is not presented in projectors. At the same time, unlike the voice control function, the voice assistant does not just turn on this or that function, mode, makes it louder, quieter, but allows you to perform certain operations in applications, whether it is to launch the desired clip on Youtube or display the weather in the browser.

The power consumed by the projector during normal operation. Both the high consumption of the device and the requirements for power supply providing depend on this indicator: for example, heavy professional projectors of 3500 W and above cannot be plugged into standard sockets, they require a special connection format.

Keep in mind that when using traditional mercury or gas discharge lamps, high brightness inevitably requires high power. Energy efficient LED projectors do not have this disadvantage, but they are still relatively uncommon, and LED is not always a suitable type of lamp.