The relationship between industrial cameras and frame grabbers

Industrial cameras are an important part of machine vision systems and industrial inspection applications, which have the advantages of high image stability, high transmission ability and high anti-interference ability. At present, most of the industrial cameras on the market are based on CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) sensors.

The frame grabber is the interface between the image acquisition part and the image processing part. Generally, it has the following functional modules:

1. The image signal receiving and A/D conversion module is responsible for the amplification and digitization of the image signal. There are capture cards for color or black-and-white images. The color input signal can be divided into a composite signal or an RGB component signal.

2. The input and output interface of the camera control is mainly responsible for coordinating the camera for synchronization or realizing asynchronous re-shooting and timing shooting.

3. Bus interface, responsible for high-speed output of digital data through the internal bus of the PC, generally PCI interface, the transmission rate can be as high as 130Mbps, fully competent for the real-time transmission of high-precision images. It also consumes less CPU time. When selecting a frame grabber. Factors such as the functional requirements of the system, the accuracy of image acquisition and the matching with the output signal of the camera should be taken into account.

The data interface of industrial cameras mainly includes network interface, USB interface, Cameralink interface, Coaxpress interface, 1394 Firewire interface, etc. Among them, the network interface and USB interface generally do not need to be equipped with an additional capture card (not that the capture card is not needed, but because the network port and USB port are too commonly used, the capture card is integrated into the computer motherboard), and the remaining interfaces all need to be equipped with the corresponding image capture card.

The industrial camera needs to be matched with the frame grabber to be used normally, and generally needs to be matched with the following:

1. The matching of video signals, there are two formats for black and white analog signal cameras, CCIR and RS170 (EIA), usually the capture card supports both kinds of industrial cameras;

2. Resolution matching, each board only supports cameras within a certain resolution range;

3. Matching of special functions, if you want to use the special functions of the camera, first determine whether the board card used supports this function, for example, if you want multiple cameras to take pictures at the same time, this capture card must support multi-channel, if the camera is progressive scanning, then the acquisition card must support progressive scanning;

4. Interface matching, determine whether the interface between the camera and the board matches.