CCD detection method
At the time of purchase, you can take the following methods: turn on the power, connect the video cable to the monitor, turn off the lens aperture, see if there is a bright spot when the image is black, and the snow on the screen is not big. These are the most simple and direct detection of the CCD chip. The method does not require other specialized instruments. Then you can open the aperture and see a still life. If it is a color camera, it is best to take a colorful object and check whether the image on the monitor is color cast, distorted, and the color or gray level is smooth. A good CCD can restore the color of the scene well, making the object look clear and natural; and the image of the defective product will have a color cast, even if it faces a piece of white paper, the image will show blue or red. Individual CCDs have impurities on the CCD target surface due to dust in the production workshop. Under normal circumstances, impurities will not affect the image, but in low light or microscopic imaging, fine dust will also cause adverse consequences if used. Such work must be carefully selected.
CCD camera division
a. According to the image color
Color camera: suitable for detailed detailing of scenes, such as identifying the color of clothing or scenery.
Black and white camera: Suitable for areas with insufficient light and areas where lighting cannot be installed at night. Black and white cameras can be used when monitoring only the position or movement of the scene.
b. According to resolution sensitivity, etc.
Image pixels below 380,000 are general type, especially products with 250,000 pixels (512 × 492) and a resolution of 400 lines. The image pixel is in the high resolution type of 380,000 or more.
c. According to the size of the CCD target
CCD chips have been developed in a variety of sizes: most of the chips currently in use are 1/3" and 1/4". When purchasing a camera, especially when the camera angle is relatively strict, the size of the CCD target surface, the cooperation between the CCD and the lens will directly affect the angle of view and the sharpness of the image. 1 inch - the target size is 12.7 mm wide by 9.6 mm high and 16 mm diagonal. 2/3 inch - the target size is 8.8 mm wide x 6.6 mm high and 11 mm diagonal. 1/2 inch - the target size is 6.4 mm wide by 4.8 mm high and 8 mm diagonal. 1/3 inch - the target size is 4.8 mm wide x 3.6 mm high and 6 mm diagonal. 1/4 inch - the target size is 3.2 mm wide x 2.4 mm high with a diagonal of 4 mm.
d. According to the scanning system, the PAL system is divided into NTSC system.
China uses interlaced scanning (PAL) (CCIR for black and white), with a standard of 625 lines and 50 games. Only non-standard systems are used in medical or other specialized fields. In addition, Japan is an NTSC system with 525 lines and 60 fields (EIA in black and white).
e. According to the power supply
110VAC (NTSC is mostly of this type), 220VAC, 24VAC. 12VDC or 9VDC (** is mostly of this type).
f. divided by synchronization
Internal synchronization: The synchronization signal generated by the synchronization signal generation circuit in the camera is used to complete the operation.
External synchronization: Use an external sync generator to feed the sync signal to the external sync input of the camera.
Power synchronization (linear lock, linelock): Vertical push synchronization with camera AC power.
External VD synchronization: The VD sync pulse input on the camera signal cable completes the external VD synchronization.
Multi-camera external synchronization: fixed external synchronization for multiple cameras, so that each camera can work under the same conditions, because each camera is synchronized, so even if one of the cameras is switched to other scenes, the synchronized camera will not distortion.
g. Divided by degree
The CCD is further divided into:
Normal type: Illumination required for normal work 1~3LUX
Moonlight type: the illumination required for normal work is about 0.1 LUX
Starlight type: illumination required for normal operation is less than 0.01 LUX
Infrared type: illuminated by infrared light, can also be imaged without light
h. By appearance:
Organic plate type, pinhole type, hemisphere type.
CCD camera installation and adjustment
a. How to install the lens
There are two types, C type and CS type. Both threads are 1 inch 32 teeth and 1 inch in diameter. The difference is that the distance between the lens and the CCD target surface is different. The distance from the reference surface to the focus of the C type mount is 17.562 mm. There is one more length of the dedicated ring than the CS type distance CCD target surface, and the CS type distance from the focal point is 12.5 mm. Don't underestimate this ring. Without it, the lens and camera will not focus properly and the image will become blurred. So before installing the lens, take a look at whether the camera and the lens are the same interface. If not, you need to increase or decrease the ring according to the specific situation. Some cameras do not need a ring, but use a rear image adjustment ring (such as Panasonic products). When adjusting, use a screwdriver to loosen the screw on the adjusting ring and turn the adjusting ring. At this time, the CCD target surface will be opposite to the mounting base (front). Exercise also plays a role in the circle. In addition (such as SONY, JVC) is similar to the rear image adjustment ring, its fixing screws are generally on the side of the camera. After loosening, adjust one of the gears at the top to make the image clear without adding or subtracting the ring.
b.AGCON/OFF (automatic gain control)
The camera has a video amplifier that amplifies the signal from the CCD to a usable level. The amplification is the gain, which is equivalent to a higher sensitivity. However, in a bright light environment, the amplifier will be overloaded and the video signal will be distorted. When the switch is ON, the lens aperture is fully opened under low light conditions, and the gain is automatically increased to obtain a clear image. When the switch is OFF, a natural and low-noise image can be obtained at low brightness.
c.ATWON/OFF (automatic white balance)
When the switch is turned ON, the characteristic/color temperature of the light source is detected through the lens, so that the white level is automatically and continuously set, and the gain of the red and blue signals can be controlled even if the characteristic/color temperature is changed.
d.ALC/ELC (automatic brightness control / electronic brightness control)
When the ELC is selected, the electronic shutter continuously and automatically changes the exposure time of the CCD image sensor according to the brightness of the incident light (generally continuously adjusted from 1/50 to 1/10000 second). When this mode is selected, the ALC auto iris lens can be replaced with a fixed or manual iris lens.
It should be noted that in outdoor or bright environments, due to the limited range of ELC control, ALC lenses should be selected; under certain lighting conditions, the following may occur:
There is a strong tailing or blurring on high-brightness objects such as spotlights or windows.
The image is noticeably flickering and color reproducibility is unstable.
The white balance has periodic changes. If these phenomena occur, an ALC lens should be used.
e.BLCON/OFF (backlight compensation switch)
When strong and useless background lighting affects the sharpness of important objects in the middle, the switch should be turned to the ON position. Note: 1 When using with the pan/tilt or the lighting changes rapidly, it is recommended to put the switch in the OFF position, because the lens aperture speed is slow in the ON position; 2 if the desired object is not in the middle of the image, the backlight compensation may not Will fully play its role.
f.LL/INT (synchronous selection switch)
This switch is used to select the camera synchronization mode, INT is internal synchronization 2, 1 interlaced synchronization; LL is power synchronization. Some cameras also have an LLPHASE power synchronous phase controller. When the camera is used in the power sync state, the device can adjust the phase of the video output signal, and the adjustment range is about one frame. (Adjustment requires professional staff)
g.VIDEO/DC (lens control signal selection switch)
There are two kinds of control signals for the ALC auto iris lens. When the auto iris lens that needs to be used for the DC control signal is mounted on the camera, the DC position should be selected. When an auto iris lens with a video control signal is required, the VIDEO position should be selected.
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