In the surveillance system, the camera is also known as camera or CCD (Charge Coupled Device) that is charge coupled device. Strictly speaking, the camera is a general term for the camera and lens, and in fact, the camera and lens are mostly purchased separately, the user according to the size of the target object and the distance between the camera and the object, by calculating the focal length of the lens, so each user needs the lens is based on the actual situation, do not think that the camera already has a lens.
The main sensing component of the camera is the CCD, which has high sensitivity, small distortion, long life, anti-vibration, anti-magnetic field, small size, no residual image, etc. CCD is the electric coupling device (Charge Couple Device) for short, it can change the light into an electric charge and can store and transfer the charge, but also the stored charge out of the voltage change, so it is the ideal camera It is an ideal camera element. It is a new device to replace the camera tube sensor.
CCD principle of operation is: the subject reflects the light, spread to the lens, the lens focused on the CCD chip, CCD according to the intensity of light accumulation of the corresponding charge, the periodic discharge, resulting in a picture of the electrical signal, after filtering, amplification process, through the camera output terminal output a standard composite video signal. This standard video signal with the home video recorder, VCD player, home video camera video output is the same, so you can also record or received on the TV set to watch.
Second, CCD classification
CCD camera selection and classification CCD chip is like the human retina, is the core of the camera. Most of the cameras on the market is Japan SONY, SHARP, Panasonic, LG and other companies to produce the chip, now South Korea also has the ability to produce, but the quality is slightly inferior. Because the chip production using different levels, the manufacturers to obtain different ways and other reasons, resulting in CCD acquisition effect is also very different. In the purchase, you can take the following methods of detection: turn on the power, connect the video cable to the monitor, close the lens aperture, see if there are bright spots when the image is completely black, the screen is not a big snowflake, these are the most simple and direct way to detect the CCD chip, and does not require other special instruments. Then you can open the aperture, look at a still life, if the color camera, it is best to ingest a brightly colored objects, to see if the image on the monitor is off-color, distortion, color or grayscale is smooth. A good CCD can restore the color of the scene well, so that the object looks clear and natural; and the image of the defective product will have color bias, even in the face of a white paper, the image will show blue or red. Individual CCD due to the dust of the production plant, CCD target surface will have impurities, in general, impurities will not affect the image, but in low light or microscopic camera, tiny dust can also cause adverse consequences, if used for such work, must be carefully selected.
1, according to the imaging color division Color camera: suitable for scene detail identification, such as identifying the color of clothing or scenery. Black-and-white camera: suitable for areas with insufficient light and night can not install lighting equipment in the area, when only monitoring the location or movement of the scene, you can choose a black-and-white camera.
2, according to the resolution sensitivity and other divisions Image pixels below 380,000 for the general type, especially 250,000 pixels (512 * 492), the resolution of 400 lines of products most common. Image pixels in more than 380,000 high-resolution type.
3, according to the CCD target surface size CCD chip has developed a variety of sizes: most of the chips currently used for 1/3 “and 1/4″. In the purchase of cameras, especially when the camera angle has more stringent requirements, the size of the CCD target surface, the CCD and the lens with the situation will directly affect the size of the field of view and image clarity. 1 inch – target surface size of 12.7mm wide * 9.6mm high, 16mm diagonal. 2/3 inch – target surface size of 8.8mm wide * 6.6mm high, 11mm diagonal. 11mm. 1/2 inch – the size of the target surface is 6.4mm wide * 4.8mm high, diagonal 8mm. 1/3 inch – the size of the target surface is 4.8mm wide * 3.6mm high, diagonal 6mm. 1/4 inch – the size of the target surface is 3.2mm wide * 2.4mm high, diagonal 4mm.
4, according to the scanning system division PAL system, NTSC system. China uses interlaced scanning (PAL) system (black and white for CCIR), the standard for 625 lines, 50 fields, only medical or other professional fields are used to some non-standard system. In addition, Japan for the NTSC system, 525 lines, 60 fields (black and white for EIA).
5, according to the power supply 110v (NTSC system is more of this type), 220VAC, 24VAC. 12VDC or 9VDC (miniature cameras are more of this type).
6, according to the synchronization division within the synchronization: synchronization signal generated by the camera synchronization signal generation circuit to complete the operation. External synchronization: the use of an external synchronization signal generator, the synchronization signal is sent to the camera’s external synchronization input. Power synchronization (linear lock, line lock): use the camera AC power supply to complete the vertical push synchronization. External VD synchronization: the VD synchronization pulse on the camera signal cable input to complete the external VD synchronization. Multiple cameras outside synchronization: multiple cameras fixed outside synchronization, so that each camera can operate under the same conditions, because each camera synchronization, so that even if one of the cameras converted to other scenery, synchronization camera picture will not be distorted.
7, according to the degree of division, CCD is also divided into.
Normal illumination required for normal work 1 ~ 3LUX
Moonlight type illumination required for normal work about 0.1LUX
Starlight type illumination required for normal work 0.01LUX or less
Post time: Oct-01-2021