The test monitoring camera mainly tests the clarity and color reproducibility, illuminance, and backlight compensation, followed by the monitoring camera distortion, power consumption, and minimum operating voltage. The following steps are the measurement steps of clarity and color reproducibility, and illumination and backlight compensation First introduce.
1. Measurement of sharpness: when multiple surveillance cameras are tested, the same lens should be used, (recommended as fixed focus, two variable lens), the center circle of the test card appears on the left and right sides of the monitor screen, clear Accurately count the total 10 sets of vertical lines and 10 sets of horizontal lines that have been given. Represents the vertical resolution and horizontal resolution respectively, and the corresponding group has given the line number. If the vertical line is 350 lines and the horizontal line is 800 lines, it is better to use a black and white monitor. During the test, you can focus on the distant object or focus while measuring. It is best to use both to see the difference of this camera (convergence to far and near).
2. Test of the color reproducibility of the surveillance camera: the color monitor should be selected to test this parameter. First, observe people and clothing from a distance to see if there is any color distortion, compare the objects with bright colors, look at the response sensitivity of the surveillance camera, put the color picture book in front of the surveillance camera, see the picture is clearly defined, too light or too dark The moving color objects should be photographed to see if there is color tailing, delay, blur, etc. The test conditions are as follows. When the latest illuminance of the camera is 50V, it should be measured under the illuminance of 50 + 10V, that is, add 10 volts to the latest illuminance of each surveillance camera, and the aperture should be kept in the closest state.
3. Illumination: place the surveillance camera in a dark room, with active 220V self-incandescent lamps in the front and back of the dark room. A voltage regulator is set up to adjust the voltage of the voltage regulator to adjust the brightness of the dark room lamp. The voltage can be adjusted from 0V to 250V . Indoor lighting can also be adjusted from the darkest to the brightest. During the test, the camera's iris is opened to the maximum and the next minimum illuminance value is recorded (the active light is dimmed with a voltage regulator so that the built-in dark room picture cannot be seen). Hit to the minimum and record the next lowest illuminance value. You can also adjust the pressure of the front and rear lights separately.
4. Surveillance camera back light compensation: There are two methods to test this parameter: one is to turn on the pressure regulating lamp on the front side of the camera when it is at the brightest in a dark room, and then place a picture or text under the lamp to monitor When the camera is facing the light, you can see whether the image and text can be seen clearly, the picture is not dazzling, and adjust the AL, AX shift switch to see if there is a change, which effect is best. The other is to take the camera out of the window when the sunlight is sufficient, and see if the images and text can be seen clearly.
5. Surveillance camera distortion: To see the distortion of the surveillance camera, place the test card on the front of the camera so that the entire sphere appears on the screen, see if the ellipse is round, move the camera forward, see if the center of the circle is magnified, then test the edge from a distance Whether the corner and frame are curved or not.
6. The power consumption of the surveillance camera: the lowest working voltage, use a multimeter to measure the current, and use a small voltage regulator to adjust the voltage.
In the security system, the current image generation mainly comes from the CCD camera. CCD is the abbreviation of charge coupled device (charge coupLED deice). It can convert light into electric charge and store and transfer the electric charge. It can also take out the stored electric charge. The voltage changes, so it is an ideal camera element. The CCD camera composed of it has the characteristics of small size, light weight, partial influence of magnetic field, anti-shock and impact characteristics, and is widely used.
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