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An ALS That Does RGB

My oh my, how the smartphone has colored our (or at least my) expectations. And color is the operative word here.

When you think, “ambient light sensor (ALS)” (yes, I know you think the parenthetical too), what do you think next? That sensor on the smartphone that can tell whether the ambient light is high or low so that it can adjust the display and keyboard backlights and such? Yeah… me too.

So then I see an announcement from Maxim about their new ALS. And it separates out colors. Now… color me stupid, but is it that someone doesn’t want their phone to react if they’re, say, in a darkroom with red light? That would make no sense – because no one uses darkrooms anymore. [Prepares for filmophile rage…]

It’s actually not that crazy; we did cover Intersil’s RGB sensor recently, and we noted there that an RGB sensor can help with tinted glass, but it was also set out in contrast to an ALS.

So here’s me feeling kinda dense, so I checked in with Maxim. Who kindly and gently helped me remember that there are more applications out there than just cellphones. Who knew.

They listed as exemplary applications:

  • Color sensors
  • Contrast sensors
  • Color sorting
  • Gas and fluid analysis
  • Label presence
  • Lid insertion verification
  • Shrink-wrap presence
  • Tamper-proof seal confirmation
  • Visual inspection replacement
  • Automatic display brightness

In other words, there are many sensing applications – particularly in an industrial environment – that benefit from analysis of the ambient light. And that might involve looking at very specific colors or fractions of colors. Which is why they have three color sensors and feed the separate color components for use in detection algorithms.

Now, based on the Intersil definitions, this would be an RGB sensor, as contrasted with an ALS. In Maxim’s terminology, this is an ALS. You can rationalize either nomenclature; I just feel better knowing there might be some miniscule rationale for my occasional lapses into states of confusion. (No need to suggest that they’re more than occasional, thank you anyway.)

Interestingly, though, Maxim focuses on different applications from the ones Intersil was suggesting; Intersil seemed more focused on displays (not just phones, but TVs and such), LED lighting, and cameras – less industrial in flavor than what Maxim has outlined. Which I guess goes to show that there are many ways to use an RGB sensor, or ALS with RGB, or whatever you want to call it.

On the heels of yet another light sensor that senses UV without a specific UV sensor – that is, by using a single visible light sensor that also detects into the UV range, and then extracting the UV by algorithms – I checked in to see whether this truly had three sensors or whether the colors were extracted from a single sensor. Answer: yes, three sensors.

You can find more detail in Maxim’s announcement.

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