Katarzyna Petru
Great colours, very high brightness and deep, pitch-black darkness. What connects these three features?
It is certainly the fact that they have nothing to do with the fact that we are talking about a laser projector.
These devices are slowly replacing the well-known lamp projectors, but the marketing of some manufacturers has gone so far that we decided to clarify the issue of lasers.
How does a laser projector work?
What comes to mind when we imagine the operation of a laser projector? It is possible that in our imagination, we picture a device that emits a laser beam directly onto a screen, drawing an image pixel by pixel. If that were the case, one would be able to achieve all the features we mentioned at the very beginning. Unfortunately, it does not work that way. A far more appropriate name is a projector with a laser light source.
This technology replaces the projector's lamp itself, while the rest of the device remains unchanged.
Therefore, in such a projector, we still have an image converter, a processor, and a lens, and it is these 3 elements that determine the blackness, colours, and especially the sharpness and resolution of the image.
So what will we gain by replacing the traditional lamp with a laser light source?
Blue laser with a phosphor wheel
We can mention a few real advantages, but they depend on the type of the particular laser.
Currently, there are two solutions on the market. The first is a blue laser with a phosphor wheel. Its operation principle is similar to that of an LED bulb. The laser beam excites the phosphor, and white light is generated, which is full spectrum. To obtain colour from it, it must be filtered through a matrix or by a colour wheel in DLP projectors.
This solution does not provide more saturated colours than a classic lamp in a projector. For gamers or film enthusiasts playing 4K content in HDR, we do not have good news. This laser does not enrich the colour palette, which is so needed in this type of material. It also does not eliminate the rainbow effect in DLP projectors, which many users complain about. This manifests in the fact that behind bright contours, we see a rainbow. Of course, each of us may have different feelings about this effect, so it is best to test it ourselves to see if it bothers us, even before purchasing a DLP projector.
So does the laser with a phosphor wheel significantly improve image quality? We must state that unfortunately it does not.
Tricolour RGB laser
The second solution uses 3 RGB lasers and such a construction has a real advantage over the lamp.
This is due to the fact that the waves have a narrow bandwidth, so we automatically have a richer colour palette, and the DLP colour wheel becomes unnecessary, which means the rainbow effect is diminished.
In the case of this solution, we can confidently say that it is a better technology than a lamp, considering the two issues mentioned above. However, is the difference really that significant?
The improvement in the rainbow effect can be debatable, as lasers can operate faster than the colour wheel, but they don’t necessarily have to. In this case, everything depends on the manufacturer.
In terms of the colour palette, the matter is much more complex.
It must be stated that projectors with a three-colour laser offer us highly saturated colours, which cannot be achieved using traditional methods. However, it should be taken into account that strong colours are not synonymous with accurate representation.
In the case of standard Full HD movies, the desired palette is Rec.709
This is provided by almost every technology currently used in home cinema projectors.
If we are talking about 4K films and games in HDR, they utilise a very wide colour gamut BT.2020, which we can see below.
Unfortunately, a large portion of the video content available on discs or streaming platforms is limited to the DCI-P3 colour gamut, as this is the system most commonly used by film studios. To fully (or almost fully) replicate the capabilities of this gamut, we need a high-quality lamp projector, for example:
Epson EH-TW9400 - 100%
JVC RS540 - 97%
SONY VPL-VW590 - 89%
From what we already know, it is evident that RGB laser is significantly better than traditional solutions; however, considering the content we play in our homes, this does not translate to a substantial gain or leap in quality.
Let us also remember that the ability to achieve saturated colours has nothing to do with colour accuracy or the smoothness of tonal transitions.
They depend on the image sensor and image processor, not on the light source, as we mentioned at the beginning of this article.
What technology does the projector use?
Now that we know two technologies, namely the unhelpful blue laser that adds nothing to image quality and the advanced tri-colour RGB, let's see what specific manufacturers have to offer us.
HISENSE:
120L9HA - The so-called laser TV, or short-throw projector with a screen included. Here we have a clear indication of the use of RGB laser.
100L5HD - Unfortunately, we do not have clear information about the technology used.
Optoma - This manufacturer does not provide such information on its website. It’s a bit strange, and we don’t see the point in hiding the full specifications. However, our keen editorial eyes have found a clue in the graphic below.
This photo suggests that a simpler solution with a phosphor wheel is used here, which is confirmed by the data we collected during calibration with our clients.
Epson also does not share such information; however, from our experience and measurements, it appears that this manufacturer uses a phosphor wheel, just like Sony and JVC. Nevertheless, the latter two incorporate additional filters that enhance colour gamut coverage in the higher models of their products, as well as converters that do not produce the rainbow effect.
At ViewSonic and Benq, this information is provided directly on the website:
Some manufacturers also offer small projectors that use LEDs as a light source, and this solution is similar to a tricolour laser.
Durability of laser and lamp
What is the durability of a laser source like? Manufacturers declare 20,000-30,000 hours before the brightness drops by half.
This is several times more than traditional lamps, whose lifespan is counted at 3,000-5,000 hours. In practice, brightness drops after just 1,500 hours, and we know of cases where customers had to replace the lamp after only 1,000 working hours.
Unfortunately, we do not have such research trials for lasers, but among our 2 customers, there was a situation where the source lost a significant portion of its power after just under 3,000 hours. In one case, the issue was resolved under warranty, but in the other case, the entire module was deemed to need replacement, which was estimated at...... 20,000 PLN.
As we can see, there is no doubt about the superiority of lasers over lamps in terms of durability, but in the event of a failure, the cost can be shocking.
Replacing a lamp costs 800-1,800 PLN, so the price per hour of viewing is 0.40-0.90 PLN with frequent replacements. Is that a lot? Judge for yourselves.
Power consumption and brightness
Let’s tackle another claim made by laser projector manufacturers, namely the lower power consumption while achieving the same brightness as a traditional lamp.
It’s hard to verify this, as there are no two identical devices differing only in the light source. However, if there is such a difference, it is unlikely to translate into more savings than a few pounds over the course of a month.
Speaking of brightness, laser projectors are not brighter than their lamp-based counterparts. The actual brightness hovers around 2000 lumens.
Bear in mind that reality brutally confronts the dry data provided by manufacturers. In the case of the well-known company Optoma, the actual brightness can differ by as much as 60% from the figures stated in the specifications. We may elaborate on this another time :)
Another argument presented in favour of laser projectors is the lack of need for warming up to operate, and then cooling down after use.
We might wonder whether this is really a significant factor in choosing a device. Surely, we often don’t even notice the noise after turning off a lamp projector. But in this regard, everyone has a choice and their own opinion :)
Is it worth it?
As you can see, a laser projector is still an ordinary projector that uses a laser light source instead of a lamp. It does not automatically offer a better image than its traditional counterpart, nor does it become an alternative to a television.
When choosing a particular device, we need to pay special attention to what technology has been used. A three-colour laser is definitely a better option, as it provides a richer colour palette and less rainbow effect in DLP projectors.
The greatest advantage of a laser projector is its durability, although, as we can see, there are exceptions.
This does not mean that lamp projectors have become obsolete. On the contrary, they are still good devices, such as the EPSON EH-TW9400. In our studio, we also have the classic projector JVC RS540 and we are in no hurry to replace it. This is because changing the image source to laser makes very little difference, if any at all. The main variable in quality is the lens, image sensor, processor, and software.
And which technology do you advocate? What do you use in your home theatres? Share this in the comments!
