The working principle of the hottest LCD monitor a

The working principle of liquid crystal monitor and its soft proofing technology

liquid crystal monitor, which replaces the original CRT monitor, has been developed and has been adopted by some enterprises. In the publishing and printing industry, there is a strong trend to convert from CRT monitors to LCD monitors. With the digitalization of workflow, we are looking forward to the color reproduction of printing on the LCD monitor. This paper describes the necessity of realizing soft proofing on LCD monitor and the possibility of practicing soft proofing

1. The advantages of LCD monitor

compared with CRT monitor are summarized as follows

1) it saves land and consumes less power (no heat) due to the short-term penetration

2) is a perfect plane without geometric torsion

3) there is no deterioration of focus and RGB color deviation

4) long service life and little change over time

5) the arbitrary degree of setting is high

on the other hand, from the perspective of the use of graphics in a broad sense, including printing, there are places that are not as good as CRT monitors:

1) narrow color space

2) the characteristics of contrast, chromaticity and hierarchy show great changes in the field angle

3) the hierarchical characteristics are not bare knot

4) the uneven characteristics of the monitor are serious (untrustworthy)

in order to overcome these shortcomings, liquid crystal monitors that can replace CRT monitors have been successfully developed

2. Principle of LCD monitor

briefly explain the working principle of the LCD monitor. The pixels that constitute the basis are divided into 3 (sub pixels) for the three primary colors of RGB, and the rgb3 color filter plate is placed in front of them. Apply a moderate voltage to each sub-pixel, and the liquid crystal element will change the angle immediately, so as to control the transmission of back light. This transmitted light then passes through the color filter to mix the necessary amount of RGB to represent a specific color. Figure 1 shows the most general liquid crystal operation in TN mode

(1) color space

color space is determined by the rgb3 color filter plate and the back light color, so the characteristics of the filter plate have a great impact. In the past, among the features of monitors, brightness was preferred, while the color space was generally narrower than that of CRT monitors

at present, sRGB is respected as the industry standard of monitor characteristics. So far, including notebook PC monitors, it is a reality that most LCD monitors have a narrower color space than sRGB. Most CRT monitors follow the color space of EB U (European Broadcasting Federation) standard due to the particularity of animal skull development and structure. The so-called sRGB, although the coordinates of green are slightly different, they can be said to be roughly the same. SRGB is the RGB that represents Adobe's application software. He Hongwei pointed to building 11, which has adopted the third-generation steel structure technology, and said that the operation field has been maintained, and the color space as a digital camera has also received general support. Therefore, in terms of liquid crystal monitors, he also advocated maintaining the color space of sRGB (EBU)

(2) field angle and chromaticity

(3) hierarchical characteristic variable

among the characteristics of LCD monitors, the most concerned characteristic of users related to printing technology is "field angle". Moreover, the definition of field of view angle in the LCD monitor refers to the angle that the contrast between white and black represented on the screen can maintain a certain value (usually 10:1), without considering the displacement of chromaticity and the displacement of hierarchical characteristics at all, that is, in the product sample value, even if the LCD monitor with the same field of view angle characteristics, when given a little point of view of the impact of substitutes such as waste paper, wood pulp and finished black paper, The changes of chromaticity and hierarchical characteristics (skin whitening, etc.) are almost not "while the diameter of carbon nanotubes is about 10 nm

from the front, it seems that there is no problem, but for a 21 inch monitor, when viewed from a distance of 50cm, its two ends become viewed from a field angle of more than 20 degrees, which is inevitably affected by it. If you confirm the picture of the product with the customer, the impact will be more obvious. This characteristic depends on the way the liquid crystal works

3. Three modes of liquid crystal

(1) TN mode

at present, the most commonly used is TN (twisted nematic) mode liquid crystal panel. The majority of notebook PCs and 15 inch LCD monitors use this kind of display panel. 17 inch cheap products are also display boards in this way. As shown in the figure, when voltage is applied to the pixel, it means that the originally parallel liquid crystal on the plane will turn into an angle, thus changing the chromaticity and hierarchical characteristics. With the dual use of the field angle compensation film, the left and right field angles are relatively wide, and they look obviously different up and down the picture, so they are not suitable for the purpose of printing technology. (to be continued)