An increase in imaging system throughput can be realized by using a camera with a higher frame rate. Often these high speed cameras require high-powered frame grabbers. Switching to another frame grabber could have a major impact on the system. This can be avoided by using cameras with an image burst technology.
In general, an industrial digital video camera consists of 3 building blocks that can handle their own maximum data rate (frame rate):
- The sensor
- The internal processing (FPGA, memory, internal pipeline)
- The interface to the rest of the system (Camera Link, GigE Vision, CoaXPress, ...)
In certain situations, the interface is limiting.
- With certain 8 Megapixel CCD cameras the sensor can acquire images at 16 frames per second (fps). If such a camera has a GigE-Vision interface only 8 fps can be sent over the interface at 10 bit.
- Modern CMOS sensors can acquire at very high speeds and many cameras are limited by the interface. If such a 4 Megapixel CMOS camera has a 2-tap Camera Link Base interface, the maximum frame speed is 40 fps.
Cameras that have a buffered pipeline architecture, such as Adimec’s OPAL and QUARTZ Qs series, can facilitate image capture at the higher rates than the interface can handle. This is possible due to the presence of a buffer memory that can temporarily store the images to delay the output. Operating in this manner is referred to as Burst Mode. During continuous operation of the camera a ring-buffer mode should be employed.
Ringbuffer memory for burst mode operationBy using a camera with burst mode, full sensor frame rates can be exploited for short periods of time without requiring a higher performance interface or frame grabber. This can be advantageous for applications requiring a limited sequence of images captured at a high speed, such as:
- License plate capture on a passing car
- Inspection of a passing device in an inspection machine
Click below for more information about the Adimec QUARTZ Qs series with burst mode.