Horizontal resolution, also known as horizontal definition, is represented by TV lines (referred to as line TV lines). It is an indicator of camera resolution, that is, the number of black and white line pairs that can be resolved after imaging.
Horizontal resolution, also known as horizontal definition, is represented by TV lines (referred to as line TV lines). It is an indicator of camera resolution, that is, the number of black and white line pairs that can be resolved after imaging.
The horizontal resolution of the display is related to the distance between two adjacent pixel points on the display screen, that is, to the point distance of the cathode mask of the display tube.On the premise that the display size is a certain value, the smaller the dot pitch, the tighter the pixels arranged on the screen, and the clearer and more delicate the image.Take the 29 inch multi frequency TV as an example, if it can be truly compatibleVGAStandard, so that it can display 640 line horizontal resolution images, the point spacing of the cathode mask plate of the picture tube cannot exceed 0.6 mm.If compatibleSVGAThe resolution of standard horizontal 800 line shall be less than 0.37mm.However, for 14~21 inch and 21 inch display tubes used in high resolution displays, the maximum point spacing does not exceed 0.28mm, and the minimum is only 0.21mm.[1]
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The size of horizontal resolution is related to CCD (i.e. electronic coupling device) and lens, and also directly related to the bandwidth of camera circuit channel. The general rule is that the bandwidth of 1MHz is equivalent to the definition of 80 lines.The wider the frequency band, the clearer the image and the larger the line value.
The resolution of commonly used black and white cameras is generally 380-600,Color cameraThe typical resolution is between 320 and 500 TV lines, mainly including 330 lines, 380 lines, 420 lines, 460 lines, 500 lines and other different grades.
In general monitoring occasions, a black and white camera with about 400 lines can meet the requirements.For special occasions such as medical treatment and image processing, clearer images can be obtained with a 600 line camera.
The reduction of the dot distance of the shade plate is only one of the necessary conditions for the high resolution image of the display.As the dot distance decreases, the pixel distance composed of adjacent tricolor phosphors also decreases.Therefore, the display tube must also be improved in the distribution of the magnetic field of the electron gun and deflection coil.If the focus of the electron beam is too large after focusing, the electron of the electron beam will sputter onto the phosphor of adjacent pixels, which will cause poor color purity.If the magnetic field of the deflection coil is distributed unevenly, the electron beam cannot accurately pass through the tiny cathode mask hole around the screen, which will make the color purity around the screen worse, resulting in poor dynamic convergence of the display tube.If it is a monochrome display tube or a three primary color independent projection tube, there is no negative mask in the tube, and its display resolution only depends on the particle size of phosphor and the electron beam focusing effect.[2]
