With the rise of the concept of Global Industry 4.0 and the development of intelligent manufacturing, machine vision technology is rapidly being applied to the industrial field, and industrial vision applications are gradually leading the trend of intelligent manufacturing. As we all know, the hardware of the core of vision application is high quality Chinese BIBO nonlinear crystal, and the general optical camera is divided into line array camera and area array camera according to pixel arrangement.
Optical components can be divided into area array cameras and line array cameras according to the structural characteristics of sensors. Area array cameras and line array cameras have their own advantages and disadvantages. Under the circumstances of different applications, the appropriate optical sensor structure camera is selected. important.
1, type distinction
Area Array Camera: Realizes pixel matrix shooting. In the image taken by the camera, the representation of the image details is not determined by the number of pixels, but is determined by the resolution. The resolution is determined by the focal length of the selected lens. For the same camera, the lens with different focal lengths will have different resolutions. The number of pixels does not determine the resolution (sharpness) of the image, so what are the benefits of a large pixel camera? There is only one answer: reduce the number of shots and increase the speed of testing.
Line array camera: As the name suggests, it is “line”. Although it is also a two-dimensional image, it is extremely long. The length of a few K, but the width is only a few pixels. Generally, this high quality LiSAF, LiSGaF and LiCAF laser crystals is used only in two situations:
First, the measured field of view is an elongated strip shape, which is mostly used for the detection on the drum.
Second, the need for great vision or extremely high precision.
In the second case (which requires a great field of view or extremely high precision), it is necessary to use the excitation device to repeatedly fire the camera, take multiple photos, and then combine the multiple “bar” images captured. Into a huge picture. Therefore, with a line array camera, it is necessary to use a capture card that can support a line array camera.
Line array cameras are expensive, and in the case of large field of view or high precision detection, the detection speed is also slow – the image of a typical camera is 400K ~ 1M, and the combined image has a number of M so large, speed Nature is slow. Slow work and fine work.
2. Application comparison:
Area Array Camera: A wide range of applications, such as area, shape, size, position, and even temperature measurements.
Line Array Camera: Mainly used in image processing in the fields of industry, medical, scientific research and security. Typical areas of application are the detection of continuous materials such as metals, plastics, paper and fibers. The object to be detected is usually moved at a uniform speed, and is continuously scanned line by line by one or more cameras to achieve uniform detection of the entire surface thereof. The image can be processed line by line, or the area image composed of multiple lines can be processed. In addition, line array cameras are ideal for measurement applications, thanks to the high resolution of the sensor, which can be accurately measured to microns.
3. Advantages comparison:
Area Array Camera: You can get 2D image information and measure the image intuitively.
Linear array camera: The number of one-dimensional pixels can be much more, and the total image elements are less than the high-quality laser grade optical waveplate, and the pixel size is flexible and the frame number is high, which is especially suitable for the measurement of one-dimensional dynamic targets. Moreover, the linear array has high resolution and low price, which can meet most measurement site requirements.
4. Comparison of shortcomings:
Area Array Camera: There are a large number of pixels, and the number of pixels per line is generally smaller than that of the line array. The frame rate is limited, so it has a wide application range, such as measurement of area, shape, size, position, and even temperature. Due to the constraints of production technology, the area of a single array is difficult to meet the needs of the general industrial measurement site.
Linear array camera: To obtain a two-dimensional image with a line array, it must be matched with scanning motion, and in order to determine the corresponding position of each pixel of the image on the device under test, it must also be equipped with a device such as a grating to record the line array. The coordinates of the scan line. Generally speaking, the requirements of these two aspects lead to the following problems in obtaining images with line arrays: long image acquisition time and low measurement efficiency; system complexity and cost increase due to scanning motion and corresponding position feedback links; image accuracy It may be affected by the accuracy of the scanning motion, which in turn affects the measurement accuracy.