CCD camera purchase tips
1. What is a CCD camera?
CCD is the abbreviation of Charge Coupled Device, it is a semiconductor imaging device, so it has the advantages of high sensitivity, anti-glare, small distortion, small size, long life, anti-vibration and so on.
2. The working mode of CCD camera
The image of the subject is focused on the CCD chip through the lens. The CCD accumulates a corresponding proportion of charge according to the intensity of the light. The charge accumulated in each pixel is shifted out point by point under the control of the video timing. Video signal output. Connect the video signal to the video input terminal of the monitor or TV to see the same video image as the original image.
3. Choice of resolution
The index for evaluating the resolution of the camera is the horizontal resolution, whose unit is line pairs, that is, the number of black and white line pairs that can be resolved after imaging. The resolution of commonly used black and white cameras is generally 380-600, and the color is 380-480. The larger the value, the clearer the imaging. For general surveillance occasions, a black and white camera with about 400 lines can meet the requirements. For special occasions such as medical treatment and image processing, a 600-line camera can get a clearer image.
4. Imaging sensitivity
Usually the minimum environmental illumination requirement is used to indicate the camera sensitivity. The sensitivity of the black and white camera is about 0.02-0.5 Lux (lux), and the color camera is mostly above 1 Lux. The 0.1Lux camera is used for ordinary surveillance occasions; at night or when the ambient light is weak, it is recommended to use a 0.02Lux camera. When used with a near-infrared light, a low-illumination camera must also be used. In addition, the sensitivity of the camera is also related to the lens, 0.97Lux / F0.75 is equivalent to 2.5Lux / F1.2 is equivalent to 3.4Lux / F1.
4. Reference environmental illuminance:
100,000 Lux in summer sunshine, 10000 Lux in cloudy day outdoor
TV studio 1000Lux from 60W table lamp 60cm tabletop 300Lux
Indoor fluorescent lamp 100Lux at dusk 10Lux
Candlelight at 10cm Lux at 20cm at night 0.1Lux
5. Electronic shutter
The time of the electronic shutter is between 1 / 50-1 / 100000 seconds. The electronic shutter of the camera is generally set to the automatic electronic shutter mode. The shutter time can be automatically adjusted according to the brightness of the environment to obtain a clear image. Some cameras allow users to manually adjust the shutter time to suit certain special applications.
6. External synchronization and external trigger
External synchronization refers to the use of the same synchronization signal between different video devices to ensure the synchronization of video signals. It can ensure that the video signals output by different devices have the same frame and line start and end time. In order to achieve external synchronization, a composite sync signal (C-sync) or composite video signal needs to be input to the camera. External synchronization does not guarantee that users get a complete continuous frame of images from a specified time. To achieve this function, you must use some special cameras with external trigger functions.
7. Spectral response characteristics
The CCD device is made of silicon material, which is more sensitive to near infrared, and the spectral response can be extended to about 1.0um. The peak of its response is green light (550nm), and the distribution curve is shown on the right. In the case of covert surveillance at night, you can use near-infrared lamps to illuminate, so that the human eye cannot see the environment clearly, but it can clearly image on the monitor. Because the CCD sensor has a layer of transparent electrodes that absorb ultraviolet light, the CCD is not sensitive to ultraviolet light. The imaging unit of the color camera has red, green and blue filter bars, so the color camera is not sensitive to infrared and ultraviolet.
8. The size of the CCD chip
The imaging size of the CCD is commonly used 1/2 ", 1/3", etc., the smaller the imaging size, the smaller the camera volume can be made. Under the same optical lens, the larger the imaging size, the larger the angle of view. Chip size imaging surface size (width X height) diagonal 1/2 6.4x4.8mm 8mm 1/3 4.8x3.6mm 6mm
The retractable earphone is a type of earphone cable that can be freely retractable and free to control the earphone cable as needed. The principle of this earphone design is to inject liquid gallium indium alloy into the elastic polymer tube, which can be normally conductive and free to stretch. When you need to use it, take out the earphone cable and start using it. When you use it, you can retract it. After retracting, the overall volume is small, it is particularly convenient to carry, and there is no trouble with the winding of the earphone cable.
Retractable Earphones,Retractable Headphones,Retractable Wireless Headphones,Retractable Bluetooth Earphones
Shenzhen Linx Technology Co., Ltd. , https://www.linxheadphone.com