LCoS technology. Projector technologies: DLP, LCD (3LCD), LCoS LCoS vs. All

D-ILA®- an officially registered trademark of JVC, which means that this product uses an original design based on an LCoS display, a reticulated polarizing filter and a mercury lamp. D-ILA implies a three-chip LCoS solution. You can also often see the abbreviation HD-ILA - D-ILA technology with Full HD resolution.

SXRD™ is a registered trademark of Sony for products made with LCoS technology

Technology principle

The principle of operation of a modern LCoS projector is close to 3LCD, but unlike the latter, it uses not translucent LCD matrices, but reflective ones (this LCoS is already related to DLP technology).

General scheme of a three-chip projector based on LCoS.

A reflective layer is located on the semiconductor substrate of the LCoS crystal, on top of which there is a liquid crystal matrix and a polarizer. Under the influence of electrical signals, liquid crystals either cover the reflective surface or open, allowing light from an external directional source to be reflected from the crystal's mirror substrate.

As in LCD projectors, LCoS projectors today use only three-chip circuits based on monochrome LCoS matrices. As in 3LCD technology, three LCoS crystals, a prism, dichroic mirrors, and red, blue, and green light filters are used to form a color image.

In the late 90s, at the dawn of technology, JVC offered single-chip solutions based on LCoS color matrices. In them, the light flux was divided into RGB components directly in the matrix itself using an HCF filter (eng. Hologram Color Filter - holographic color filter ). This technology is called SD-ILA(English) single D-ILA). Philips also developed single-matrix solutions.

But single-chip LCoS projectors are not widely used due to a number of shortcomings: three times the loss of light flux when passing through the filter, which, among other things, imposed restrictions due to matrix overheating, poor color reproduction quality, more complex technology for the production of color LCoS chips.

Story

history of technology

The prehistory of the emergence of LCoS technology begins in the 60-70s of the XX century. And, like many other technologies, including DLP, it was born thanks to military orders.

In 1972, the LCLV was invented at the Hughes Research Labs of Howard Hughes' Hughes Aircraft Company, which at that time was the center of the most advanced research in the field of optics and electronics. Liquid Cristal Light Valve - liquid crystal optical modulator ). For the first time, LCLV technology was used to display information on large screens in US Navy command and control centers. Back then, these devices could only display static information.

The development of technology continued and the term English. Liquid Cristal Light Valve was replaced by English. Image Light Amplifier (ILA) as more appropriate.

ILA differs from D-ILA in that liquid crystals are controlled by a photoresist, which is subjected to a modulating beam generated by a cathode ray tube.

In the early 90s, Hudges and JVC decided to join forces to work on ILA technology. September 1, 1992 was the official date for the formation of the joint venture Hughes-JVC Technology Corp.

The first commercial projector based on ILA technology was demonstrated by JVC in 1993. Over 3,000 of these projectors were sold during the 1990s.

The use of a cathode ray tube as an image modulator in ILA devices imposed restrictions on the resolution, size, and cost of the device and required complex alignment of optical paths. Therefore, JVC continues to research to create a revolutionary new reflective matrix that would solve these problems while maintaining the advantages of the technology. And in 1998, the company demonstrates the first projector made using D-ILA technology, in which the image modulating device in the form of a CRT beam - photoresist bundle is replaced by CMOS control elements implemented in the semiconductor structure of the substrate - hence the name of the "direct drive ILA" technology - ILA with direct control. Sometimes D-ILA stands for "digital ILA" (digital ILA), this is not entirely true, but it also correctly reflects the essence of the changes in D-ILA technology from analog device controlled (CRT) ILA.

There was also an intermediate, also already digital, technology between ILA and D-ILA, which was not widely used - FO-ILA, - where the control cathode ray tube was replaced by a bundle of fiber optics (Fiber Optic), which transmitted a modulating signal from the surface of a monochrome monitor.

first wave

second wave and disappointments

Philips

Despite multi-million dollar plans, Philips is wrapping up LCoS production by the end of 2004.

Intel

In January 2004 at CES, Full HD took over a significant share of it, making LCoS technology mass. However, by the end of 2004, Intel announced that this project was being phased out.

The main reason for this was most likely not technological problems (although LCoS chips are much more difficult to manufacture than CMOS chips - processors), but the lack of market prospects - by this time it had already become clear that the FullHD TV market would be captured by more technologically advanced and cheaper LCD TVs. And the market for projection TVs and projectors per se is too small to justify the investment.

Intel spent 5 years and $50 million on LCoS technology. investment

Sony

The first SXRD projector (based on a proprietary chip) was demonstrated by Sony in June 2003. The following year, Sony announced a projection TV based on SXRD technology. By 2008, the company had phased out all projection TVs, including models based on SXRD technology.

But the company did not refuse to release projectors. Today, Sony launches installation projectors with a resolution of 4096x2160 (based on the 4K-SXRD chip) and aperture up to 11000 ANSI lumens

Advantages and disadvantages of technology

Benefits determined by the technological capabilities of LCoS compared to competing 3LCD and DLP technologies:

• Greater coefficient of useful filling of the working space of the matrix. Since LCoS control elements are placed behind the reflective layer, they do not interfere with the passage of light, unlike translucent LCD matrices, which reduces the "mesh" of the image and minimizes the "comb effect". The distance between the matrix elements is only a few tens of micrometers, and the fill factor (the ratio of the total working area of ​​the pixels to the total area of ​​​​the matrix) for LCoS exceeds this figure for both LCD projectors and DLP.

• LCoS chips are more resistant to powerful radiation than DLP and LCD matrices. That allows you to make the most powerful installation projectors using LCoS technology.

• LCoS is ahead of LCD and DLP in terms of the maximum available resolution.

• Deeper blacks and higher contrast than 3LCD projectors.

• The response time of liquid crystals of the LCoS matrix is ​​less than the crystals used in transmissive matrices in 3LCD technology.

• LCoS inherits the advantages of 3LCD technology over single-chip DLP projectors - no flicker and "rainbow effect".

Projectors based on LCoS

Despite the disappointments of the mass market players, LCoS technology continues to attract interest from manufacturers and consumers.

Projectors based on it are positioned in the segment of the highest quality level and in the professional field of application - ultra-large resolution projectors for cinemas.

To date, projectors using LCoS technology (D-ILA, SXRD) are produced by Canon, LG, Barco, CrystalView, DreamVision.

It is the third most common after DLP and 3LCD (LCD) technologies, but occupies a much smaller market share.

Synonyms for LCoS are the abbreviations D-ILA (eng. Direct Drive Image Light Amplifier) by JVC and SXRD (eng. Silicon X-tal Reflective Display) by Sony. D-ILA is a registered trademark of JVC, which means that this product uses an original design based on an LCoS display, a reticulated polarizing filter and a mercury lamp. D-ILA implies a three-chip LCoS solution. You can also often see the abbreviation HD-ILA. SXRD is Sony's registered trademark for products made using LCoS technology.

Technology principle

The principle of operation of a modern LCoS projector is close to 3LCD, but unlike the latter, it uses reflective rather than translucent LCD matrices. Just like DLP technology, LCoS uses epi-projection instead of the traditional over-the-air projection found in LCDs.

A reflective layer is located on the semiconductor substrate of the LCoS crystal, on top of which there is a liquid crystal matrix and a polarizer. Under the influence of electrical signals, liquid crystals either cover the reflective surface or open, allowing light from an external directional source to reflect off the crystal's mirror substrate.

Like LCD projectors, LCoS projectors today mainly use three-chip circuits based on monochrome LCoS matrices. As in 3LCD technology, three LCoS crystals, a prism, dichroic mirrors, and red, blue, and green color filters are usually used to form a color image.

However, there are single-chip solutions in which a color image is obtained by using three high-power, fast-switching color LEDs that produce red, green, and blue light in sequence, such solutions are produced by Philips. Their power is low.

In the late 1990s, JVC offered single-chip solutions based on LCoS color arrays. In them, the luminous flux was divided into RGB components directly in the matrix itself using an HCF filter (eng. Hologram Color Filter - holographic color filter). This technology is called SD-ILA (English single D-ILA). Philips also developed single-matrix solutions.

But single-chip LCoS projectors are not widely used due to a number of shortcomings: three times the loss of light flux when passing through the filter, which, among other things, imposed restrictions due to matrix overheating, low color rendering quality, and more complex technology for the production of color LCoS chips.

Story

The history of the emergence of technology

In 1972, the LCLV (Liquid Cristal Light Valve - liquid crystal optical modulator) was invented in the Hughes Research Labs of the Howard Hughes Aircraft Corporation, which at that time was the center of the most advanced research in the field of optics and electronics. For the first time, LCLV technology was used to display information on large screens in US Navy command and control centers. Back then, these devices could only display static information.

The development of technology continued and the term LCLV was replaced by English. Image Light Amplifier (ILA) as more suitable.

ILA differs from D-ILA in that the liquid crystals are driven by a photoresist, which is fed with a modulating beam generated by a cathode ray tube.

In the early 1990s, Hughes and JVC decided to join forces to work on ILA technology. September 1, 1992 was the official date for the formation of the joint venture Hughes-JVC Technology Corp. The first commercial projector based on ILA technology was demonstrated by JVC in 1993. Over 3,000 of these projectors were sold during the 1990s.

The use of a cathode ray tube as an image modulator in ILA devices imposed restrictions on the resolution, size, and cost of the device and required complex alignment of optical paths. Therefore, JVC continues its research to create a fundamentally new reflective matrix that would solve these problems while maintaining the advantages of the technology. In 1998, the company demonstrated the first projector made using D-ILA technology, in which the image modulating device in the form of a CRT beam - photoresist bundle was replaced with CMOS control elements implemented in the semiconductor structure of the substrate - hence the name of the direct drive ILA technology. » - ILA with direct control. Sometimes D-ILA stands for "digital ILA" (digital ILA), this is not entirely true, but it also correctly reflects the essence of the changes in D-ILA technology from analog device controlled (CRT) ILA.

There was also an intermediate, also already digital, technology between ILA and D-ILA, which was not widely used - FO-ILA - where the control cathode ray tube was replaced by a bundle of optical fibers based on fiber (Fiber Optic), which transmitted a modulating signal from the surface of a monochrome monitor.

First wave

Second wave

Philips

Sony

The first SXRD projector (based on a proprietary chip) was demonstrated by Sony in June 2003. The following year, Sony announced a projection TV based on SXRD technology. By 2008, the company had phased out all projection TVs, including models based on SXRD technology. But the company did not refuse to release projectors. Today, Sony launches projectors for large installations and digital cinema with resolutions up to 4096×2160 (based on the -SXRD chip) and apertures up to 21,000

A head-to-head introduction to Philips PicoPix series projectors took place at IFA 2010. On the eve of IFA 2011, our test lab was approached by their representative, distinguished by the presence of a built-in multimedia player. Of particular interest is the projection technology used, since we have had LCD and DLP projectors with LED light sources, but we have not yet tested LED projectors with reflective LCD matrices (LCoS).

Delivery set, characteristics and price

Appearance

In terms of dimensions, the projector is almost pocket-sized, in the sense it will fit into a pocket, but only in a large one. Its body is made of plastic, while the top and bottom panels are black with a mirror-smooth, relatively scratch-resistant surface, and plastic with a silver surface around the perimeter. On the top panel are the logo, control buttons, charge indicator and focus wheel.

During operation, when you press any button and receive a command from the remote control, the blue illumination of the icons on the buttons turns on, which goes out after a few seconds. The window of the only IR receiver is located in the most unexpected place - in the corner, at the transition of the right sidewall to the rear panel. There are ventilation grilles on the right and left panels, behind which miniature loudspeakers are hidden. In addition, there is a headphone jack on the left side,

and on the right is the power switch.

The front panel has a lens niche framed by a metal ring and a ventilation grill,

on the back - interface connectors, a slot for SD memory cards and a power connector.

On the bottom there is a reclining leg, another ventilation grille, a tripod socket and a rubber pad.

With the foot pressed due to the convex bottom, the projector is unstable on a flat plane, so when projecting from a table, it is better to either recline the foot (but the projection will be directed upwards), or mount the projector on a miniature tripod included in the package. Also included in the package is a case with two hard walls, where the projector is hardly squeezed in and nothing else fits.

Remote controller

The remote is small with few buttons. The button designations are large and contrasting, but using such a remote control is still inconvenient. But small. You need to direct the remote control approximately towards the IR receiver window, the remote control does not work by reflection from the screen.

Switching

Philips seems to have decided to earn extra money by selling accessories, so a high-quality video signal is input through a proprietary small-sized connector, and there is not a single adapter for this connector in the package. But we were lucky, together with the projector we got an adapter cable from this connector to a mini D-sub 15 pin plug and a 3.5 mm mini jack plug, which allows you to connect the projector to a computer with a VGA video output and an audio output in the form of a regular 3.5 jack mm.

In addition to this cable, adapters for connecting to a source of component video signal (and stereo audio signal), as well as for connecting to "apple" technology - to iPod and iPhone, are declared as additional accessories. Without additional expenses, the projector can be connected to a source of composite video signal and stereo audio signal, since an adapter for a four-pin 3.5 mm minijack jack (to regular RCA jacks) is still included in the kit, as well as a USB adapter from a mini-B plug to a jack type A. USB storage can be connected to the USB port. Apparently only FAT(32) is supported. The power on the port is enough to run a typical USB HDD with a 2.5-inch drive. When a card reader is connected, the projector recognizes all inserted memory cards at the same time, displaying them in the browser as separate root folders. The projector can be directly connected to a computer via USB, the projection will turn off automatically and the computer will access the projector's built-in memory and the SD card if it is in the projector's card reader. The projector comes with an external power supply that can be used for operation and for charging the built-in battery. The latter, according to the manufacturer, charges in 3 hours, and already, according to our data, provides continuous operation in bright mode for 1 h 44 min.

Menu and localization

The menu uses a smooth and fairly large sans-serif font. When the projector is turned on, the main page with labeled icons is displayed, from where you can launch browsers with or without restrictions on files of a certain type, switch to an external signal source (A / V input takes precedence over VGA / component) or go to the settings menu.

Image settings can also be called directly during operation - first by calling the brightness slider with the remote control buttons, then using the up and down arrows to select the desired setting (contrast, saturation or volume). There is a Russian version of the on-screen menu. Translation into Russian is generally adequate. When working with USB-drives or SD-cards, the Cyrillic alphabet in the names of files and folders is displayed correctly. Tags from audio files are partially displayed (in the browser), Russian must be encoded in Unicode (UTF-8). A user manual is recorded on the built-in memory, and the Russian version of the manual can also be downloaded from the company's Russian website as a PDF file. You can also download the latest firmware update from there. At the time of testing, there was version 2.1, to which we successfully updated the projector.

Projection control

The focal length is fixed and does not change. Focusing the image on the screen is done by rotating the ribbed wheel. The projection is directed straight ahead, so that the center of the projection area is almost on the axis of the lens. Such straightforwardness is not always convenient. There are no transformation modes, the projector simply displays the image on the entire projection area. There is no coup and reflection of the projection either.

Image Adjustment

The projector has several preset profiles with fixed picture settings and one custom profile that allows you to adjust brightness, contrast and saturation.

Luminance measurement

Luminous flux, contrast and illumination uniformity were measured according to the ANSI method.

Measurement results for Philips PPX1430 projector:

The maximum luminous flux is less than the declared 30 lm. In complete darkness, this brightness is enough for projection onto a screen up to 0.5 m wide, in a barely lit room it is better not to try to project more than on an A4 sheet. The uniformity of illumination of the white field is acceptable. The contrast is low. We also measured contrast by measuring the illumination in the center of the screen for white and black areas, the so-called. contrast full on/full off.

The contrast is below the declared 400:1. However, since the luminous flux is low, the black level is correspondingly low, and as a result, the black color is perceived as quite deep.

We did not disassemble the projector, but the test results suggest the following principle of forming a full-color image. The projector uses a single liquid crystal array on a reflective substrate (LCoS), which is sequentially illuminated by red, green, and blue LED sources. During the pulse, each cell of the matrix transmits (or rather, it only polarizes, but transmits / does not transmit the polarizer) light for a certain time interval, the longer it is, the higher the perceived intensity of the color component of the corresponding image pixel. The human eye performs an integrating function, forming the resulting pixel color based on the pulses of three colors. The principle of operation is somewhat similar to DLP technology. To illustrate, here is the dependence of brightness on time for white and pure primary colors, as well as for gray and dark shades of colors:

For clarity, all brightness graphs, except for the lower ones, are shifted upwards and aligned with red, green, and blue pulses.

It can be seen that the decrease in intensity is achieved by decreasing the duration of transmission. You can also notice that adaptive overclocking of the matrix is ​​\u200b\u200bused to speed up the switching - for bright colors it is on, for dark colors it is off. For example, the response time for bright green is 0,23 ms to turn on and 0,02 ms to turn off, and for dark green - 0,70 ms and 0,28 ms respectively. (Note that the resulting response times, especially turn-off times in the case of bright colors, can also be affected by the modulation of light sources.)

An analysis of the dependences of brightness on time showed that the frequency of alternating colors is 60 Hz (with input signal from 60 Hz vertical frequency). This is a rather low frequency (corresponds to a single-speed light filter), the rainbow effect is very pronounced, moreover, artifacts are visible even without eye movement - bright objects in motion are stratified into their primary colors.

To assess the nature of the increase in brightness on a gray scale, we measured the brightness of 256 shades of gray (from 0, 0, 0 to 255, 255, 255) at Brightness= 6 and Contrast= 5. Note that the setting Brightness adjusts the black level, and the setting Contrast- white level. The adjustment step is large, so with a range of shades of 0-255 there is either a small blockage in the highlights, or the white brightness is slightly lower than the maximum possible brightness. The graph below shows the increase (not an absolute value!) in brightness between adjacent halftones:

An increase in the increase in brightness can be traced, but the spread in the increase is large. With the specified settings in the shadows, all shades are distinguished:

Approximation of the obtained gamma curve gave the indicator 1,46 , which is less than the standard value of 2.2, while the approximating exponential function deviates slightly from the real gamma curve:

Sound characteristics and power consumption

Attention! The reported sound pressure levels from the cooling system are based on our method and cannot be directly compared with the projector ratings.

The projector is relatively quiet, although it is strange that when the brightness is reduced, the cooling mode does not change. We measured consumption at the input of an external power supply with a fully charged built-in battery. When the projector is turned off while the battery is being charged, the mains power is 11 Tue

The built-in speakers are quite loud for their size and don't sound as bad as you might expect. Even the stereo effect can be traced. When headphones are connected, the built-in speakers are muted. The headphones sound loud, but without a margin. Medium and high frequencies differ (low ones are not enough), there is little distortion, noise is not heard in pauses.

Video path testing

VGA connection

Testing was mainly conducted at a VGA resolution of 800 by 600 pixels and a vertical refresh rate of 60 Hz. The result of the auto-tuning function for the VGA signal parameters requires manual position correction, but there is none, so the picture was cropped on both sides by a couple of pixels, although the output was one to one, without interpolation. The white field in the center had a noticeable greenish tint. Black fields were uniform in color tone and brightness. The geometry is good, the deflection of the borders inward is a couple of millimeters per 50 cm of width. The image is slightly out of focus in the center. The width of the color border at the boundaries of objects, due to the presence of chromatic aberrations in the lens, is generally insignificant, and only in the corners it reaches 1/3 of a pixel. The border between the pixels is barely noticeable. Thin colored lines one pixel thick are output without losing color fidelity. Apparently, only the resolutions specified in the specifications are supported, any deviation from them led to a black screen with a list of supported modes.

Working with home player

Work with composite video sources was tested using . The clarity of the image is slightly reduced due to interpolation to the resolution of the projector matrix. Weak gradations of shades in the shadows and in the light areas of the image are well distinguished (a blockage in the shadows and highlights after adjusting the levels with the settings Brightness And Contrast does not go beyond safe limits). The picture is displayed in the fields.

The range close to black can be ignored, since the color rendering is not so important in it, and the measurement error of color characteristics is high. The color temperature is very high, as is the deviation from the blackbody spectrum. The reason for this is the underestimated brightness of the red color. Unfortunately, the ability to manually edit the color balance is not provided.

Built-in media player

From USB media and SD cards, the projector can display pictures ( JPG, gif, BMP, uncompressed TIF And PNG). Images can be viewed in a slideshow with a preset interval (2-20 seconds) and a random transition effect. Pictures are displayed inscribed to the nearest projection boundaries while maintaining the correct proportions. There is an increase with a shift of the enlarged area.

From audio files are played MP3, OGG And WMA with almost any combination of sample rate and bit rate, only 24-bit and lossless WMA is not supported. In addition to them, the projector player also coped with AAC-files and MPEG-1/2 Layer 2 audio files (with extension MPA). When playing audio files, the projector turns off the projection without fail, playback can be paused, and that's it.

The declared list of containers and codecs is very extensive, we have not tested all of their combinations, limiting ourselves to our selection of popular video file types. As a result, it turned out to be easier to list what is not reproduced. These are the files WMV And OGM. The player managed to show everything else up to Full HD resolution with a high stream. External subtitles are not supported. Embedded text subtitles are partially supported (good in MKV and bad - very small output - in AVI). The proportions of the picture are preserved, but anamorphism in MKV is not processed. There is no switching between audio tracks and subtitles - only the first tracks are always played. When displaying an image across the screen, a characteristic wave of desynchronization often runs from top to bottom, apparently the player does not adjust the frequency of displayed frames to the screen refresh rate. Fast forward, rewind, and pause playback work.

The projector has a built-in browser that allows you to view the contents of the built-in memory, connected USB storage devices, and inserted SD cards. You can switch between these drives with the return button while in the main menu. Folders and files can be copied and deleted.

conclusions

For advanced techno-maniacs, the Philips PPX1430 projector is interesting as a concept of a device with an unusual way of forming an image - "eternal" LED light sources, LCD on a reflective substrate, pulsed sequential color output. For ordinary users, this device is rather a fun toy - to watch a movie and make an impression by taking out a self-sufficient miniature version of a home theater from your pocket.

Advantages:

• Small size and weight
• USB media and SD card support
• Built-in memory 2 GB
• Built-in multi-format player
• Tripod included

Flaws:

• Color reproduction is different from standard
• Non-standard interface connector
• No required adapters included
• Noise reduction in economy mode

Judging by the statistics, this topic is of interest to many readers and I will gladly continue it.

Today, as I promised, we will talk about LCD technology, or rather 3LCD (why I will tell you below).

If we turn to the great and terrible Wiki, then the history of the emergence of LCD projectors goes back to the 70-80s of the last century, when an American inventor Gene (Eugene) Dolgoff (judging by the name and surname of a native American) began development and brought to life the design of the LCD- a projector capable of competing with the then “God” of projectors - a CRT-based device (cathode ray tube).

Accordingly, the first LCD projectors contained a single LCD matrix, similar to those used in televisions. The advantage of this scheme was simplicity. But in fact, a drawback immediately emerged - with an increase in the power of the light source, which was necessary to increase the luminous flux, and as a result of the brightness of the image, the LCD panel began to overheat. The result of “work on the bugs” was the emergence in 1988 of a technology called 3LCD, and in 1989, 3 companies Epson, InFocus and Sharp released the first projectors based on it.

What did the engineers come up with, and where did the name 3LCD come from?

How a 3LCD projector works. To form an image, a system of lenses, dichroic mirrors and three LCD matrices are installed in the 3LCD projector. It all works like this. The light from the source (in the case of an LCD projector, it is always a lamp, since the only LCD LED projector prototype presented by Epson never went to the masses) falls on the so-called dichroic mirrors installed in the optical unit. These mirrors (filters) transmit light of one of the colors (light in a certain spectrum) and reflect the rest of the light. Passing through a system of mirrors, the light is divided into 3 main components R, G, B (red, green and blue), each of the colors falls on the LCD matrix intended for it.

By themselves, the matrices installed in the LCD projector are monochrome (that is, they form a black and white image). They work in the same way as in LCD TV, i.e., unlike the DLP chip, they do not reflect, but transmit light, and at high magnification, figuratively, they are a lattice, where the bars carry control channels, and voids between the bars - pixels - points of the image.

These same pixels can close and open, thereby passing or not passing light (or passing it partially). When light hits the matrix of one of the colors, the LCD panel forms an image of this color and sends it to a prism, where the images of three colors are added to a full-color image, then sent through the lens to the screen. Hence the name 3LCD. I hope the description is clear, and if not, watch the video describing my tirade clearly.

Such a scheme, as usual, has its advantages and disadvantages.

Due to the fact that the image is formed inside the projector, and it hits the screen already “blinded”, and is not displayed by color, it is believed that the image from LCD projectors is less straining on the eyes. In Japan, there have even been studies on this topic, and they seem to have proved this fact, but I have no evidence of this, nor evidence to the contrary. But the fact remains that in LCD and LCOS projectors the picture is projected onto the screen in full color, in single-matrix DLP projectors it is a sequence of color images added in the brain.

One of the benefits stemming from the paragraph above is the absence of the “rainbow effect” I talked about in my post about DLP projectors. Here it cannot exist as such.

The next positive point in the three-matrix system is the constancy and high brightness of the color image. I have already said that when it comes to office DLP projectors, manufacturers use a white segment in the color wheel to increase brightness, which spoils color reproduction. In the case of an LCD projector, the light is also absorbed by the system components, but in the end, LCD projectors turn out to be more profitable in terms of efficiency when displaying a color image, and their color reproduction quality does not depend on the brightness of the projector.

The disadvantages of LCD projectors are non-convergence, low black level and low contrast, the so-called Screen door effect and “matrix burn-in”.

Not mixing. In fact, this deficiency is quite rare. It consists in the appearance of colored contours of objects on the image. The fact is that, as you already know, the projector uses three matrices, each of which is responsible for its own color. If these matrices are not set accurately enough in relation to each other, then the picture of one color will slightly “move out” in relation to images of other colors, then, for example, you can see a blue outline to the right of the object, and a red one to the left. Fortunately, LCD projector manufacturers are very fine-tuning the position of the panels, despite their tiny size (and imagine how big the pixels are in them!), so this misalignment usually does not exceed half a pixel (such a contour can only be seen close to the screen, and this is absolutely does not affect the image). But of course, there are cases when non-convergence can be 2 or 3 or more pixels. In this case, the user has a direct road to the service or to the seller.

Contrast and black level. DLP projectors, having appeared in 1996, made a splash in terms of black color and contrast, and from the first days, fans of this technology and manufacturers of DLP projectors actively promoted this advantage over the “oldies” in the face of LCD devices. Indeed, you could see the difference in black between DLP and LCD projectors with the naked eye. Where Malevich's "Black Square" looked really close to black on a DLP projector, LCD projectors gave out frank gray. Manufacturers of LCD matrices have begun modifying their panels, and today, about ten generations of these devices have changed (DMD chips have changed 4 generations). And one of the things that improved from generation to generation was black levels and contrast. Today it can be stated that in home theater projectors, the best representatives of the LCD camp are not inferior, and sometimes even surpass their “DLP friends” in terms of contrast and black level. In the office sector and in education, the gap in numbers and viewing in the dark remains, but firstly, it is not so noticeable, and secondly, black color and contrast during presentations in ambient light conditions are not so important, because black on white In principle, there is no screen in the light and cannot be.

Screen door effect. This favorite item of ardent “DLPers” “pleased me even at a time when monitors were square, and one could only dream of a 720p projector. Screen door effect is the so-called “lattice effect”. The thing is that the distance between the pixels of the DMD chip, LCD chip and LCOS chip is different. This is due to the control of chips: in LCOS and DMD, the operation of individual pixels is controlled “behind” the chip, while with the “translucent” LCD technology this is impossible, and to control the cells of the chip, it is necessary to lay control channels between them. Thus, the distance between pixels in the LCOS panel is minimal, and the useful area of ​​the chip is maximum. In LCD, on the contrary, the minimum of the three technologies is the useful area of ​​the chip and the maximum distance between image points. DLP is in between.

Despite the fact that the resolution of projectors is growing, some manufacturers of DLP projectors continue to insist that when viewing an image from an LCD projector, a grating can be seen on the screen. If you sit close to the screen - I agree with that. But if you look at the image from an adequate distance ... With SVGA resolution on a screen 2 meters wide, we have a pixel 2.5 mm in size, and the distance between them is a little less than a millimeter, and if desired, and at a distance of up to 3 meters from the screen, you can see the grating . At XGA resolution, the pixel size becomes less than 2 mm, at WXGA - 1.5 mm, at FullHD - 1 mm. What pixels and lattices can we talk about? Of course, you can see the pixels on the Retina display of the iPhone... With a magnifying glass! But the viewer does not look at the pixels, but at the picture, and here, with the normal quality of the content, you don’t notice any pixels.

"Matrix burnout". Have you ever seen a yellow image on a projector? No, not in the sense of a yellow lemon in the picture, but the whole image that smacks of yellow! There can be three reasons for such an incident.

Cigarette smoke. Often in bars, projectors hang. If smoking is allowed in the room where the projector is hung, the projector will start to turn yellow some time after installation.

It's all about cigarette smoke and the tar it contains. When deposited on the optical components of the projector, they turn into a yellow coating, which makes the image yellow and reduces brightness. And no matter what technology is used (some manufacturers of DLP projectors claim that they have a sealed optical block, so this problem does not concern them, the resin settles everywhere, including on the lens) - sooner or later the image will fade and turn yellow. And cleaning the optics from this muck is still a problem, so in a bar it is better to isolate the projector from smokers to the maximum.

Wrong setting. Everything is trite here - for example, the color temperature is set too low and voila, the image is too warm.

And finally, the “matrix burn-in” of the LCD projector. Specifically, the degradation of the polarizer of the LCD panel, which is responsible for the formation of the blue component of the image, as a result of which the image does not receive blue color and, as a result, yellowness appears.

At one time, TI (Texas Instruments), a manufacturer of DMD chips and the main opponent of LCD manufacturers on the market, conducted a study that showed that degradation occurs after 3000 hours. But the conditions under which these studies were carried out seem to be very controversial. They took the most compact, and therefore designed for mobile presentations on the road, projectors and launched them around the clock. Manufacturers of such equipment never claim that it is designed for round-the-clock operation, and mobile projectors in general are usually used no more than 3-4 hours a day.

Under normal operating conditions, degradation occurs much later - this time. 3,000 hours is 3 years of daily (on weekdays) four-hour presentations - that's two. Since the experiment, and it was carried out, if my memory serves me, in the year 2004-2005, a lot of water has flowed under the bridge and 5 generations of LCD panels have changed - that's three. Today, I would no longer pay attention to such statements.

For reference: at home, I’ve been using an LCD projector for 5 years now - it’s not that yellowness has appeared, I haven’t even changed the lamp yet (this is a word about users’ fear that the lamp needs to be changed often)!

And finally, let's get back to the good. Another significant advantage of LCD projectors is lens shift. Of course, a lens shift system can be installed in virtually any projector (regular sizes), but only in "entry" level LCD projectors it is present, while in DLP and LCOS-cameras, these will be devices of a different price range. Why did I use quotes? Because today the most affordable of FullHD-projectors with lens shift costs about 50 thousand rubles.

I have already spoken about “Lens Shift” more than once, including in the previous article in the cycle about DLP projectors, but once again I will remind you what it is. If the projector has a lens shift (Lens Shift) or, as it is also called “Lens Shift”, this means that the projector has a lens system that allows you to move the image without moving the projector itself. The shift is vertical and horizontal. Vertical lens shift has a larger range than horizontal and is much more common (until recently, it was only found in mid-range DLP projectors, and horizontal was added to high-end models). What is its function? To simplify the installation of the projector. Imagine a situation where there is no way to center the projector on the screen, but there is lens shift. In this case, the projector is installed, for example, to the left of the screen, and the picture is shifted to the right with a wheel, lever or button on the case or remote control (depending on the model of the projector). Accordingly, lens shift can be manual (wheel) or motorized (button). Unlike simply rotating or tilting the projector, lens shift does not produce keystone distortion that requires electronic correction to distort the original image. An example of how manual lens shift works is shown in the video.

The thing is mega-comfortable!

Well, that seems to be all that I wanted to tell you about 3LCD projectors. If I forgot something, comments are welcome.

The next article in this series will focus on LCOS. Don't switch

All projectors, as well as screens, lamps, mounts and other accessories are in my .

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CANON was founded in 1937 and quickly became known as a manufacturer of quality photographic equipment. The company entered the market of professional installation projectors relatively recently, but now many projects use CANON projection solutions based on LCOS technology. About this technology, about the most interesting models of the XEED line, as well as about the cases in which the manufacturer's projectors "lit up", says the company's projector specialist Alexei Makarov.

How did the history of CANON projectors begin?

CANON started producing projection lenses in 1990, and this was a logical step in the development of a lens company. After all, a projector, in fact, is a camera in reverse: light enters the camera from the outside and is focused on the matrix through the lenses, while in the projector the image appears inside and is focused on the screen through the lens.

LCoS (Liquid Crystal on Silicon) technology was developed by JVC Corporation.

The principle of operation of an LCoS projector is close to 3LCD, but LCoS does not use translucent LCD matrices, but reflective ones. On the substrate of the LCoS-crystal there is a reflective layer, on top of which there is a liquid crystal matrix and a polarizer. Under the influence of electrical signals, liquid crystals either cover the reflective surface or open, allowing light from an external source to reflect off the crystal's mirror substrate.

The benefits of LCOS technology include:

• Greater coefficient of useful filling of the working space of the matrix. Since LCoS control elements are placed behind the reflective layer, they do not interfere with the passage of light, unlike translucent LCD matrices, which reduces the "mesh" of the image and minimizes the "comb effect". The distance between the matrix elements is only a few tens of microns and the fill factor is higher than that of LCD and DLP.
• LCoS chips are more resistant to powerful radiation than DLP and LCD matrices, since all elements are placed on a cooling substrate.
• LCoS is ahead of LCD and DLP in terms of maximum available resolution.
• LCoS provides deeper blacks and higher contrast than LCD.
• The response time of the liquid crystals of the LCoS matrix is ​​less than that of the crystals used in translucent matrices in LCD technology.

What innovation did CANON bring to its products, given that third-party manufacturers were involved in the development of the actual projection technology?

First of all, a good optical system - lenses. To LCOS technology, we have added better light transmission both in the internal path and outside, and, in addition, LCOS itself (its improved version, called AISYS) is also made by us. The word XEED stands for the name of the projector line, and if the model is marked in this way, you can be sure that inside the projector there is a real LCOS and real CANON technologies. Another important point: LCOS projectors are always very small, which has allowed us to make some of the most compact 4K projectors in the world.

What is special about the optics of CANON projectors?

In projection devices, good optics are of the utmost importance. A range of CANON projector lenses use true aspherical lenses and true ED optics to achieve depth of field, significantly better focus across the entire screen area, and the ability to project images on complex surfaces, not just flat screens. Also, expensive lenses can eliminate such unpleasant phenomena as chromatic aberration, when some color separation is visible at the edges of the frame, associated with the passage of light along the edges of the lens.

If we are talking about 4K projectors, then they can also do the so-called “peripheral focusing”. This is important for objects such as, say, flight simulators where curved screens are used. Here, both the edges of the screen and the center should be in focus, and CANON 4K projectors have very tricky fixed lenses that allow for complex peripheral focusing. This is precisely the optical system, not software capabilities. Projectors XEED LCOS technology are positioned as installation and therefore all models in this series are suitable for creating multi-projections: they easily cope with geometric distortions.

Among other advantages, I would also note low weight: a 4K projector weighs about 17 kilograms and is one of the smallest in the world. So if you have a slightly larger budget than standard DLP and don't need huge lumens, LCOS projectors can be used with great success.

Tell us about the models of projectors for multi-projections

Examples of using Canon projectors for multi-projection

At a Canon in-house event in Austria: 8-projector stitching projecting a city panorama onto a large screen in high light

In flight simulators

A'DAM Toren Observation Deck, Amsterdam, The Netherlands: two projectors shine on a model of the city of Amsterdam. This is an ordinary video mapping, it tells its story, shows the sights, it all looks great.

Mobile planetarium in Germany (together with AV Stumpfl).

Museum of the history of the city of Borovichi, Borovichi region: two projectors show various artifacts on the screen in 3D.

Museum complex "Kulikovo field" (Tula region, the village of Monastyrshchino). Biggest project of 2016, honored with a special prize at the ProIntegration Awards 2016

Two of the hottest models to date are the WUX6010 and our most recent WUX6500, our seventh generation of installation projectors with LCOS technology, motorized zoom, lens shift, focus and a choice of five interchangeable objects. The stitching function is also built into the projectors, and working with this option is extremely simple: you set the area of ​​​​the frame and select the thickness of the overlap from the menu. In general, everything. That is, for simple installations, you can simply take two projectors and quickly stitch them together by pressing a button in the menu. More complex projects will require some software, but in any case, with projectors of this class, you can make wonderful multi-projections, and we have a lot of examples of such installations: this is a stitching of 8 projectors at a Canon internal event, and the A'DAM Toren observation deck, where two projectors shine on the layout of the city of Amsterdam and, using video mapping, tell the history of the Dutch capital, show its main attractions, and a mobile planetarium in Germany, where CANON projectors are used along with additional equipment and software.

In Russia, our partner, the A3V company, actively uses our projectors in various museum installations: in the Museum of the History of the City of Borovichi, in the Kulikovo Field Museum Complex. The latter was the largest project for CANON last year and was awarded a special prize at the ProIntegration Awards 2016. In total, about 30 of our projectors, including the WUX6010, are used in this project.

How much do these installation devices cost?

WUX6010 retails for 350 thousand rubles without a lens. The cost of the latter starts from 47 thousand. A more compact version of the XEED WUX500, which is equipped with the same technologies as its older brother, but with a fixed lens with a 1.8x zoom, costs 350 thousand rubles with a lens. Here, focusing, zooming and lens shift will have to be done manually, and this is the main difference between these two models, but if you put up with the need to adjust everything manually, then for this amount you get a professional installation projector weighing only about 6 kg. You can take it with you in your bag and easily place it in the cabin of the aircraft.

Are there short throw devices in the CANON projector range?

Of course, because they are very convenient. There are no very bright projectors in the CANON portfolio, and when it is possible to use a cheaper short-throw projector instead of an expensive bright projector that is installed far from the screen, we always remind the customer of this: the cable is saved, and the light does not hit the eyes, and can be used for rear projection when there is not much space behind the screen. The CANON lineup includes the WUX450ST short throw projector with a complex non-zoom lens. Its cost is 500 thousand rubles, but it is not in vain that it costs such money, because the scope of its application is incredibly wide. By the way, at the ISE 2017 exhibition, I first saw a table specially made for this projector: the projector was mounted under the tabletop and displayed the image at the level at which people are used to seeing it.

The fact is that this projector has a huge vertical lens shift, and this function is somewhat unique. The image is not distorted, not defocused, which opens up great opportunities: the projector can be mounted under the table and show the picture from above, or mounted to the ceiling and lower the picture down. The geometry is also easy to deduce.

In the project of the A3V company, the Kulikovo Field Museum, you can see a timeline indicating various historical events that have taken place in Rus' over the centuries. At first glance, it seems that the entire image on the wall is formed by two projectors, but in fact there is a third one, which is hidden from below. Due to the large lens shift, the image is aligned in geometry without any problems.

Examples of using the WUX450ST projector

In the city of Utrecht, near Amsterdam, recently, where everything but food is a projection. It is everywhere: on the walls, on the table, and even on the visitors. Projectors are placed under the ceiling, and mechanisms are screwed to the tables, which sometimes make the tables shake, a large fan also creates a certain effect. In the complex, all this is such a kind of 3D restaurant. A huge number of short-throw projectors are used here, precisely because there is little space and it is impossible to shine into people's eyes. CANON devices do their job perfectly.

ISE2015: joint installation with AV Stumpfl - a large number of projectors under the ceiling, which illuminate a large surface of the floor and walls. All this is bright, colorful and at the same time quite budgetary.

Museum of Artistic Culture of the Novgorod Land (in the process of building the exposition). Under the ceiling 10 Canon short throw projectors

What was interesting at the CANON booth at ISE 2017?

I would single out one of the installations: a special mirror was installed next to the large screen, onto which our laser-phosphorus projector projected an image. The mirror displayed the picture on a huge screen, allowing the viewer to feel himself in the thick of things: various images, panoramic photographs and so on grew before his eyes. Looked impressive and innovative.

And I would also like to tell you about the installation created jointly with the Enfitek company. They have developed a special kind of passive 3D: these are special filters that are placed either inside the projector lens or directly in front of it. To view the image, special passive glasses are used. In the installation at our booth, a rear projection was made using two 4K projectors mounted behind a screen, which, using Enfitek filters, showed a real 4K 3D image with real-time rendering. Together, this was intended to create interest in the use of high resolution projectors in all kinds of visualization projects. By the way, LCOS projectors are most often used for passive 3D.

Where can I buy Canon projectors?

One of our largest and most active distributors is the Merlion company, which always has a warehouse stock of equipment. Also, CANON equipment can be purchased from A3V, an integrator that deals with museum equipment, and from our new partner, Askrin.

Another of our distributors is located in Perm, this is the Audiovisual Systems company, which is engaged in large, serious projects - flight simulators, planetariums - and has accumulated vast experience in this difficult business. Therefore, if you have complex projects and many technical issues, you may well cooperate with them.

I am happy to answer your questions in person, offline, by phone or email. So write, let's talk.