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LG AF115 - The Quality Home Cinema Projector

We are pleased to inform our readers that this article is the second on the topic, as a our test about the projector. True, our present writing will differ from its predecessor in many ways, yet, having no other point of reference, we will rely on it on the first page.

At the beginning of our article, we eliminated the front / rear projection technique, so we don't want to go into that again. Let it be enough to (of course) test again with a front projection technique, i.e., create the image with a projector placed in front of a reflective screen.

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Projected from the front

We also talked about the most basic features that can be used to characterize a projector: projection technology, brightness, contrast (native / dynamic), dynamic / controllable iris (aperture), weight, dimensions, optical / digital zoom, lens shift (electronic / manual), projection distance and image size (min./max.), native resolution, aspect ratio, received video standards, connectors, lamp characteristics, consumption, noise emission, recommended area of ​​use. In our article, we will try to go around all the features from the point of view of our protagonist, to which, of course, we will add some explanation.

Even here, in the introduction, we must mention that for the difference between our article then and now, it is practically enough to mention one “scapegoat”: the field of application. While the HS101 is a portable presentation projector, the AF115 is a blood home theater specialist, so these two delinquents have very different characteristics.

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On the HS101 stand

As an introduction, this is what we thought, let's get acquainted with the screening technology of our main character on the next page!

Our article last September Second page we were able to learn about DLP technology in detail, and the knowledge we gained there can still be useful to us. We also learned from our article at the time that there are basically three technologies that dominate the world of projectors: CRT, LCD and DLP. There will still be three types, but we'll take the CRT out of the deck…

We've already written a lot about LCDs in our columns, so we assume this technique is known to our readers. As a reminder, at DLP, the image is produced by micromirrors on the DMD, which, depending on control, direct the light beam from the lamp and color wheel assembly to the lens.

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LCOS panel

In our case, we can practically talk about combining these two technologies - only in broad lines, of course. In effect, LCOS is a reflective technology that uses liquid crystal instead of DLP mirrors - and with that sentence, we grasped the point. In the case of Liquid Crystal On Silicon, in the reflective panel, which in DLP means a set of micromirrors, the liquid crystal is enclosed between a reflective base plate and a light-transmitting layer (the liquid crystals are implanted directly on the silicone layer). From now on, the thing is familiar: like an LCD, polarization according to the arrangement of the crystals is created, i.e. it either lets in the incoming light or it does not.

In most cases, as with the AF115, one panel per color (RGB) is used. After the color resolution, of course, they also need to be combined, i.e. four prisms are required in this system. We'll get a better understanding of how it works by looking at the picture below:

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Why is LCOS good for us? With its help, a higher filling factor can be achieved for liquid crystals, which reduces the rasterization - visible grid network (small pixel distances can be achieved at high resolution). Another advantage of the technology is that the edges of LCOS pixels form a much finer transition than the sharp pixel boundaries created by DLP micromirrors - meaning a more “analogous”, more natural effect can be achieved with them. Speaking of which, we can also mention that we can forget about the color wheel used in DLP - along with all its distractions (rainbow, noise). Of course, we wouldn’t be fair not to say that in terms of native contrast, an LCOS projector can only achieve the performance of a good DLP projector at most.

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Imaging: DLP and LCOS (SXRD)

In terms of practical implementation, the solution of two manufacturers has spread in the public consciousness: Sony and JVC, i.e. SXRD (Silicon Crystal Reflective Display) and D-ILA (Direct Drive Image Light Amplifier). Of course, both technologies use the three-chip solution presented above. Among the specifications of our AF115, the inscription SXRD also flourishes, which means that we are dealing with a semi-internal LG LG, which is by no means a bad sign…

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Sony SXRD insert


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