The small 29 mm x 29 mm format is the best way to achieve top throughput rates at the lowest costs possible. This size has established itself not just for its external appearance (camera front), but also for its drilling pattern. Most camera makers have harmonized their offerings to work with it, which gives customers significantly more flexibility.
Traditional CCD sensors were typically built around larger dimensions, such as 40-45 mm x 40-45 mm. The trend toward smaller CMOS sensors means those larger dimensions are likely to shrink into niche areas of the machine vision market.
Their replacements will be the ultra-compact 29 mm x 29 mm cameras as well as the approx. 35 mm x 35 mm format, supported by the latest generation of smaller, high-resolution CMOS sensors.