mechanical shutter and electronic shutter
Although mechanical shutter and electronic shutter are both called shutter, they are not the same concept at all.
Mechanical shutter: use springs or electromagnetic means to control the opening and closing of several blades, or two layers of curtains “scratch” the image field window with a gap of a certain width from left to right or up and down like a stage “curtain”, so that the window can obtain a “light opportunity” of a specified length of time – this is the common definition of mechanical shutter. Shenzhen Jinshikang Technology specializes in providing USB camera modules and optical lens products.
Electronic shutter: In fact, there is no “door”, but the principle that the CCD does not work when the power is off. Although the image field window is “wide open” when the CCD is off, the image cannot be generated. If the electronic time circuit is used when the shutter button is pressed, so that the CCD is only powered on for “a specified length of time”, the effect of “instant opening” of the shutter can also be achieved.
Therefore, the electronic shutter digital camera is “silent” when pressing the shutter. However, in order to meet the “psychological needs” of movie friends, some cameras can set an “electronic voice”: simulate a “click” sound to make you “happy”.
Obviously, electronic shutter is simpler than mechanical shutter and its cost will be much lower. However, it is worth noting that if the lens faces the strong light for a long time, it is easy to burn the CCD device of the “big open door” behind it through the focusing effect of the lens.
Electronic shutter is a term proposed by comparing the mechanical shutter function of the camera, which is equivalent to controlling the sensitivity time of the CCD image sensor. AES (Auto Electronic Shuttle) automatic electronic shutter automatically adjusts the electronic shutter time according to the ambient illumination (the amount of light input) to ensure the constant brightness of the output image. Shenzhen Jinshikang Technology
In the CCD camera, the shutter is controlled by controlling the charge accumulation time on the optical electrically controlled image surface. When the electronic shutter of the camera is opened, the speed of the electronic shutter of the camera can reach 1/100000 second at the fastest. For moving objects, the faster the electronic shutter, the clearer the shot.
When the surveillance camera is shooting a fast moving object, the image will be blurred due to the displacement of the object light image on the CCD photosensitive surface in a field of time. The faster the object moves, the more blurred the image is. The use of electronic shutter can improve the dynamic definition of objects, improve the clarity of images of fast moving objects, and reduce the blur of images. In addition, the combination of electronic shutter and aperture can control the exposure and affect the depth of field.
Basic principle of electronic shutter
In the absence of an electronic shutter (i.e., 1/50 of a permanent second), the time for light images to be converted into electrons is 1/50 of a second. During this period, the displacement of the light image of the moving object on the CCD photosensitive surface makes the resulting image electrical signal contain the displacement information, thus causing the image blur. Shenzhen Jinshikang Technology specializes in providing USB camera modules and optical lens products.
When the electronic shutter is used (such as 1/100, 1/1000 seconds), the time when the light image is converted into an electron is the electronic shutter time. The sampling time can be greatly shortened (the electronic shutter speed can be selected according to the speed of the moving object). The information that generates image blur will also be reduced, and the contour of the moving object will be clear.
Use of electronic shutter
As the sampling time becomes shorter when using the electronic shutter, which is equivalent to reducing the sensitivity of the surveillance camera, the level of the video signal will also be reduced. In order to ensure the amplitude of the video signal, the aperture must be opened wider. Every time the electronic shutter speed is increased by one gear, the aperture must also be increased by one gear.
Precautions for Shutter Use
When using the electronic shutter, it must be noted that if the lens faces the strong light for a long time, it is easy to burn out the CCD sensor behind the “big open door” through the focusing effect of the lens. This is similar to the past film SLR. When using curtain shutter, the curtain is easy to burn when facing the sun.
Because the imaging plane is the focus plane of the lens, it is the shutter curtain (behind it is the film) for the SLR, and it is the light-sensitive CCD for the household digital machine. Focusing sunlight on this plane will certainly burn everything in focus. The longer the focal length of the lens, the narrower the viewing angle, the more concentrated the energy and the greater the danger. This must be noted in the use of digital cameras.
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