Film output is usually involved in the process of applying film. The output of film is an exposure process similar to photography. It first converts the dot matrix image (that is, the image and text are composed of dots) processed by RIP, and then converts it into the signal that controls the laser. Using the vertical and horizontal movement of the laser relative to the film, the laser dot (that is, the dot) is hit (shot) on the corresponding position of the film to expose the corresponding position of the film, and then the unexposed part is washed out through the development and fixation process of the developer, The dot matrix image is formed on the film. In this process, film quality standard detection becomes the most important. So how should we carry out standard inspection on the quality of film? Here's a brief introduction:
Film quality standard detection method:
1. Field Density and Fog
It is the basis for measuring film quality. Fog refers to the absolute density of blank film, that is, the density of blank film measured after the densitometer is absolutely cleared (cleared to the air). Film with fog value<=0.03 is preferred, and the film between 0.03 and 0.07 is qualified. The so-called field density refers to the density value of large real plots. Because of the small area of the gray scale provided by the publishing software and the trachoma in some film films, the field density measurement value is smaller than the actual value, which is generally qualified when it is between 3.5-3.8. However, if there is a large field, it must ensure that its density value is between 4.0-4.3 to ensure the color saturation of the printed matter and not make the dark tone levels merge.
2. Dot shape, mesh angle and number of hanging lines
The dot shall be smooth, substantial, without sawtooth and tailing; The mesh angle shall meet the standard (generally 45 degrees for monochrome, 30 degrees for four-color), and shall not collide with the mesh; The number of hanging cables is suitable for printing csgia.net brush media (for example, newsprint is not higher than 120lpi, and coated paper is not lower than 133lpi).
3. Linearized value
It is the main factor to measure the film quality. Generally, it is qualified to ensure that the difference between the marked value and the measured value on the film gray scale is ≤ 2. However, because the general high-precision printing presses have a certain degree of color adjustment, we can guarantee the quality of the printed matter as long as the linearization difference is ≤ 5.
4. Film quality after exposure
It is a very late stage and a factor that is easy to be ignored. There is no trachoma on the film, no scratches on the film, no oil stains, and no "white spots" that have not been removed.
To sum up, this is the film quality standard detection method. If the film has passed this series of quality standard tests and the effect is very good, it must be a film film with qualified quality.
