Step 2: Make it precise, to ensure every pixel is produced identically
We have explained how the image is structured by design - a perfectly tessellated pattern - but that is all irrelevant if the system is incapable of delivering close to the design intent. Key to that is precision - shape, speed and repeatability. We’re afraid we can’t give away all our trade secrets, but hopefully enough to be interesting.
First of all, we need to ensure that every pixel is constructed identically, colour density aside, and is where it is supposed to be. This comes down to the optics of our system, the very high precision mechanical axes, on-the-fly electronic compensation and timing. Every pixel is produced under identical physical conditions and with accuracy at the micron scale. This level of reproducibility cannot be achieved by laser or enlargement systems at the speeds required.
It helps that we have 576 channels of light rather than 3. We can control output better because we have more time, and by scanning the head rather than bending the light with optics, we can always reproduce the same spot shape in perfect register, in three colours, wherever it is on the page.
The next challenge is to control the intensity of the light to achieve the correct colour density. We do so with up to 11-bit control on each channel. This is equivalent to an inkjet head with up to 2048 levels of greyscale. We can achieve over 4 billion colours - all without white space, of course, because we are working in continuous tone. Of course we have to do it quickly - we are controlling 13 million flashes of light every second where the intensity of the light is varied in each and every flash between a level of 0 and 2048.
All of this is the start of what gives us the colour fidelity over halftone approaches. What makes things interesting is that all LEDs have a slightly different wavelength and behave slightly differently with regard to temperature - and they emit heat as they operate. We have to compensate for that constantly by ...but that’s where we have to stop or we will give away our secrets.
In summary, using LEDs, our optics and a precise multi-axis system gives us better opportunity to control and replicate over lasers, but brings its own challenges, which we know how to overcome. The result - as near perfect a pixel as can be achieved to date, without impacting the neighbouring pixel - and we’re already working on the next two advances because we are never satisfied.