The difference between area array cameras and line array cameras

The photosensitive units (pixels) are arranged in a two-dimensional array. Each photosensitive unit in the array corresponds to a pixel. One surface of the photographed target is imaged. The target and the camera can be stationary or relatively moving. Such a camera is called an area array camera.

The photosensitive unit arrangement is one-dimensional. Each exposure only images a line on the target to form a line of images. With the relative movement between the target object and the camera, the camera continuously exposes and finally forms a two-dimensional image. Such a camera is called a line array camera.

The number of pixels scanned by a line array camera per line can range from 512 to 12,000, and the exposure of each line can also be independent of the target's movement speed, so it is also suitable for situations where the target's movement speed changes. Such as: image processing in the fields of industry, medical care, scientific research and security, etc.

Area array cameras are suitable for situations where the target object has a large format or the defect size is small, such as: printing quality inspection, PCB board inspection, shape, size, position, and even temperature measurement.

Due to production technology constraints, the area of ​​a single area array CCD is difficult to meet the field of view requirements for general industrial measurement. The advantage of the linear array CCD is high resolution, but to use the linear array CCD to obtain a two-dimensional image, it must be equipped with scanning motion. In order to determine the corresponding position of each pixel point in the image on the device under test, it must also be equipped with devices such as gratings to record the coordinates of each scanning line of the linear array CCD. Generally speaking, these two requirements lead to the following shortcomings in using linear array CCDs to acquire images: long image acquisition time and low measurement efficiency; due to the existence of scanning motion and corresponding position feedback links, system complexity and cost are increased; image accuracy may be reduced by the accuracy of scanning motion, ultimately affecting measurement accuracy.

The solution of linear array CCD plus scanning motion to obtain images is still widely used, especially when a large field of view and high image resolution are required, and it cannot even be replaced by an area array CCD. However, high resolution alone does not guarantee high image recognition accuracy. In particular, although the image obtained by the linear array CCD has high resolution, its image is more special than the area array CCD image due to the influence of the scanning motion accuracy. Therefore, when image recognition, we must not only make full use of the advantage of high resolution, but also algorithmically overcome the influence of scanning motion so that errors in mechanical transmission do not directly affect the final image recognition accuracy.