Innovative camera features

GET MORE OUT OF YOUR GIGE

VISION SYSTEM ARCHITECTURE >

Learn more about two great innovative camera features

Read more
Intelligent Lighting - Part 1

HOW SMART CAN MACHINE VISION

ILLUMINATION BE? >

Learn more about intelligent lighting | Part 1

Read more

Rolling and global shutter (CMOS sensors)

While interlaced and progressive scan terms relate to CCD sensors the terms 'global and rolling shutter' only refer to CMOS sensor technology.

Sensors with "global shutter" could be considered the same as CCD progressive scan and are used in most machine vision cameras. These sensors have the advantage that all pixels are exposed simultaneously for a defined period, called the exposure time.

In a "rolling shutter" sensor, the start and end of exposure on each row or column or individual pixel happens sequentially, so all the pixels are not exposed all at the same time. It can take up to 1/frame rate for all of the pixels on the sensor to become active. The effect will be noticed if the object is moving. See image below.

Rolling shutter sensors allow for a pixel to be designed with fewer transistors, reducing cost, and in some circumstances, increasing the well capacity and hence the quality. There are some modes of operation that can be implemented in rolling shutter cameras that give a global effect, e.g. using strobe light.