In the practical application of industrial cameras, we often see the terms area array industrial camera and line array industrial camera. Many people cannot distinguish the concepts and are often at a loss when choosing. Next, TEO will take everyone to understand the difference between these two types of sensor industrial cameras. Industrial cameras can be divided into line array cameras and area array cameras according to the structural characteristics of the sensor. TEO briefly introduces the application details of these two cameras in this article.
Line array industrial camera: As the name suggests, it is in the shape of a "line". Although it is also a two-dimensional image, it is extremely long, with a length of several K and a width of only a few pixels. Generally, this kind of camera is only used in two situations. One is that the field of view to be measured is an elongated strip, which is mostly used for inspection problems on rollers. The second is that it requires a huge field of view or extremely high precision.
In the second case, it is necessary to use an excitation device to excite the industrial camera multiple times, take multiple pictures, and then merge the multiple "strip" images taken into one huge picture. Therefore, when using a line array industrial camera, you must use a capture card that can support the line array industrial camera. Line array industrial cameras are expensive, and their detection speed is also slow in the case of large field of view or high-precision detection. The image of a general camera is 400K ~ 1M, and the merged image is as large as several M, so the speed is naturally slow. Slow work makes fine work. For the above two reasons, line scan cameras are only used in image processing in the industrial, medical, scientific research and security fields under very special circumstances.
Area array industrial camera: Camera pixels refer to the total number of photosensitive chips in the industrial camera, usually expressed in units of 10,000, arranged in a matrix, for example: MV-GE series industrial cameras, ranging from 300,000 to 29 million pixels.
For area array industrial CCDs, it has a wide range of applications and can be used for measurements such as area, shape, size, position, and even temperature. The advantage of area array CCD is that it can obtain two-dimensional image information and the measurement image is intuitive. The disadvantage is that the total number of pixels is large, and the number of pixels in each row is generally less than that of the linear array, so the frame rate is limited. The advantage of linear array CCD is that it can do a lot of one-dimensional pixels, but the total number of pixels is less than that of area array industrial CCD cameras. Moreover, the pixel size is more flexible and the frame number is high. It is especially suitable for the measurement of one-dimensional dynamic targets.
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.
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