Frame Rate

Let’s face it. When you’re trying to sell digital still cameras (DSCs), DSLRs, or PC cams to the masses and you’re dependent on the clerks working at big box retail stores to explain the finer points of your design, your product is at risk. It could become just another commodity lost in some senseless megapixel war and completely indistinguishable from the next camera sitting on a nondescript aluminum shelf. Fast frame rates can make your products distinct and help you gain a competitive advantage.

And the principle of differentiation holds true for industrial applications too, where many of our sensors can capture more than 500 frames per second (fps) of megapixel video.

Get competitive in the DSC market

For digital cameras, the Saturday afternoon youth soccer game can be the moment of greatest importance. A soccer mom stands poised with her DSC as a nine-year-old striker dribbles past the defense and kicks a piebald ball for a long arching goal. If mom is just a second too slow or God-forbid the DSC hesitates before it snaps a picture, there won’t be a souvenir. Instead, there will be a mad mom mumbling about your merchandise to everyone in the neighborhood. But if that DSC had a CMOS image sensor capable of high frame rate image capture the story would have a different ending. Mom would have set the camera in burst mode, held down the trigger, and captured 30 sequential photographs of her little Mia Hamm or Freddy Adu scoring the game-winning goal for posterity.

High frame rates enable just this sort of burst mode and can give a DSC or DSLR a considerable competitive advantage in the market. Fast frame rates can capture almost any fast motion, like a golf swing, or even produce HD video at 60 fps.

Expeditious frame rates can also improve existing features like image stabilization and auto focus by providing more information to an image signal processor, which in turn enables lickety-split response times.

High-speed industrial applications

In machine vision applications, high frame rates effectively freeze an image, allowing systems to determine if a label is straight or examine a product for defects.

TrueSNAP global shutter for clear machine vision automated inspection systems must accurately capture images of fast-moving objects. That's just what they’re designed to do. But at very high frame rates, above say 500 fps, rolling shutter sensors produce blurred or torn images, requiring more robust image processing and more complicated algorithms.

To overcome this challenge, we developed the TrueSNAP (true shutter node active pixel) global shutter. Each TrueSNAP pixel contains not only a photodiode for photon-to-electron conversion and collection, but also has an analog pixel memory (shutter node) where signal charge may be stored prior to readout. It is the inclusion of this analog pixel memory that distinguishes TrueSNAP from other pixel architectures.

Because of this pixel memory, the image sensor’s exposure time can be controlled, at both the start and end of an exposure. Exposure starts after the photodiode is released from its reset or zero signal charge state. The photodiode then integrates the incident photoelectric charge and the signal charge is transferred from the photodiode into the analog pixel memory. This transfer of signal charge to the memory ends the exposure. Once the signal charge is in the analog memory, it becomes isolated from any new incident photoelectric signals—thus the analog memory acts like a shuttering mechanism. The result is a clear image even in excess of 10,000 fps.

Fast frame rates fuel automotive apps too. In automotive applications, high frame rates translate into lower overall system costs. Shrewd system designers can take advantage of fast frame rates and context switching to feed data to two or more forward-looking systems, simultaneously providing alternating frames to each system and eliminating the need for multiple cameras.