CCD camera
CCD cameras take an image using a CCD sensor. The term "CCD camera" is used in the context of industrial cameras, as well as in the context of consumer cameras. In the old days, "CCD camera" was used to distinguish between cameras based on pickup tubes or film spools.
Today, we have to distinguish between CCD cameras and CMOS cameras. Meanwhile, the vast majority of consumer cameras are CMOS based. In contrast, the majority of industrial cameras are CCD based.
However, CMOS cameras are being used more and more in new machine vision projects. Therefore, manufacturers such as The Imaging Source offer both: CCD cameras and CMOS cameras.
CCD camera versus CMOS camera
As recently as a few years ago, only low-end consumer cameras were fitted with CMOS sensors. Quality cameras were exclusively based on CCD sensors.
Meanwhile, the quality of CMOS sensors matches that of CCD sensors. Due to the advantages of CMOS sensors (easy to integrate, power saving and lower price etc.) they even dominate professional DSLR cameras.
What are the advantages of CCD cameras?
While consumer cameras fitted with CCD sensors are considered to be outdated, many industrial USB cameras, FireWire cameras and GigE cameras still use them. On the one hand, they are long-lasting capital goods, on the other CCD sensors (still) have some advantages:
- Availability: CMOS sensors are characterized by short innovation cycles. That sounds good but actually it is a nightmare for the capital goods industry. Usually, this industry expects long-term availability.
- Global shutter: The vast majority of CMOS sensors is based on the so-called rolling shutter. Unfortunately, it skews the image of moving objects. In contrast, CCD sensors have a global shutter "by nature" and thus they have no problem with skewed images.
- Long time exposure: Exposure times of more than a minute are still a problem for CMOS sensors. Even simple CCD cameras provide exposure times of up to one hour.
Obviously, the manufacturers of CMOS sensors know about these problems and work hard to get rid of them. Therefore, it would not be surprising, if we were to see CCD cameras only in certain niches of the machine vision market in the future.
