editor's blog
Subscribe Now

Close Enough?

Not long ago, in our coverage of 3D vision, we discussed time-of-flight as one of the approaches to gauging distance. Even though it and the other 3D vision technologies are gunning for low-cost applications, it’s easy, at this point, to view them as exotic works in progress.

Well, time of flight is now being put to use for the most prosaic of duties: making sure your cheek doesn’t accidentally hang up on you.

Of course, our phones already have this feature via their proximity sensor, installed specifically for this purpose. It detects when the phone is near the face and shuts down the touchscreen, both saving power and rendering it immune to the random input it would otherwise get as it hit your cheek now and again.

As STMicroelectronics sees it, however, the existing way of judging proximity leaves something to be desired. Right now, it’s a simple process of sending light out and measuring how much gets reflected back, a method that can depend on a lot of factors besides proximity. How often such sensors fail isn’t clear to me, but ST has come forward with a new approach: using time of flight to measure how long it takes the light (regardless of the quantity of light) to make a round trip.

They do this by co-packaging an IR LED emitter, an “ultra-fast” light detector, and the circuitry needed to calculate the distance from the measurements. It also contains a wide-dynamic-range ambient light sensor. 

Is all of that needed just to keep your phone from getting too cheeky? Well, it’s clear that that’s simply the “marquee” function they address. On the assumption that you can do a lot more interesting stuff if you can measure with reasonable accuracy how far away something is (as opposed to a more binary near/far assessment), they’re betting that phone makers will want to include it so that both they and enterprising apps writers will come up with all kinds of interesting new things to do. It changes the class of apps it can manage from digital to analog (in the sense I defined them when discussing accelerometer applications).

Used in such other applications, they’re targeting a distance range of up to 100 mm (about 4 inches for those of us that grew up with non-metric intuitive visualization). They think it will work beyond that, but they’re not committing to that at this time.

You can find more info in their release.

Leave a Reply

featured blogs
Jul 3, 2020
[From the last episode: We looked at CNNs for vision as well as other neural networks for other applications.] We'€™re going to take a quick detour into math today. For those of you that have done advanced math, this may be a review, or it might even seem to be talking down...
Jul 2, 2020
Using the bitwise operators in general -- and employing them to perform masking, bit testing, and bit setting/clearing operations in particular -- can be extremely efficacious....
Jul 2, 2020
In June, we continued to upgrade several key pieces of content across the website, including more interactive product explorers on several pages and a homepage refresh. We also made a significant update to our product pages which allows logged-in users to see customer-specifi...

featured video

Product Update: What’s Hot in DesignWare® IP for PCIe® 5.0

Sponsored by Synopsys

Get the latest update on Synopsys' DesignWare Controller and PHY IP for PCIe 5.0 and how the low-latency, compact, power-efficient, and silicon-proven solution can enable your SoCs while reducing risk.

Click here for more information about DesignWare IP Solutions for PCI Express

Featured Paper

Cryptography: How It Helps in Our Digital World

Sponsored by Maxim Integrated

Gain a basic understanding of how cryptography works and how cryptography can help you protect your designs from security threats.

Click here to download the whitepaper

Featured Chalk Talk

Cloud Computing for Electronic Design (Are We There Yet?)

Sponsored by Cadence Design Systems

When your project is at crunch time, a shortage of server capacity can bring your schedule to a crawl. But, the rest of the year, having a bunch of extra servers sitting around idle can be extremely expensive. Cloud-based EDA lets you have exactly the compute resources you need, when you need them. In this episode of Chalk Talk, Amelia Dalton chats with Craig Johnson of Cadence Design Systems about Cadence’s cloud-based EDA solutions.

More information about the Cadence Cloud Portfolio