The basic theory of printing

First, the definition of printing and classification printing is the use of certain equipment and materials to repeat the pattern or text on the manuscript to the substrate. There are five basic elements required to complete a printing process: manuscripts, printing, inks, printing machinery, and substrates. Printed on the packaging plays an important role: (1) the decorative aesthetic effect. A good package must have good printing and cooperation in order to play a good role in packaging. The packaging is beautiful and beautiful, the design is novel and attractive, it gives people a beautiful enjoyment, can attract the customer's visual attention, and stimulate people's desire to buy. (2) The role of transmitting information. Printing is the bridge between the producers of goods and consumers. It should understand all the problems that customers want to know by printing the bridge, and print all kinds of information that producers want to tell consumers. Tell the consumer of the product. This information includes: product name, trademark, model number, manufacturer, site, zip code, telephone, fax, contents, usage, storage and handling, circulation, quality, bar code, shelf life, production date, and production lot number. (3) Functional effects. Full-page printing can be protected from light and used for light-sensitive foods, such as tea packaging. (4) The warning effect. For example, in the packaging of pesticides, in particular, printing a skull can make people look awkward and can warn people to use caution.
The design of patterns and texts in the printed manuscripts should carefully examine the customs and habits of the regions where the products are sold and avoid annoying and unsalable. For example, a Japanese company produces fine gold pens that are shipped to the United States for sale. Because purple camel velvet is used inside the box as a pen liner in the box, Americans do not like this color and are unmarketable. After changing to bright colors, it becomes a bestseller. Another example is that in Japan, a batch of toys are sold to India, and there is a picture of a hunter holding a waxed eagle, which is returned intact. Therefore, the pattern text must be based on the premise that it does not harm the feelings of the people in the sales region and respect the living habits of the local people. The verbatim version of the manuscript was verbatim, and many manufacturers had one less letter or letter in the English word reversed. There was no vowel sound in the word and no return was heard. There are many accidents in the printing factory.
There are various types of printing: (1) The printing can be divided into two categories, namely non-pressure printing and pressure printing. Non-pressure printing includes photography, facsimile, copying, and video recording. Gravure printing includes gravure printing, letterpress printing, screen printing, and flat printing. In pressure printing, there are also people who refer to screen printing and letterpress flexographic printing as light pressure printing, and the intaglio printing as heavy pressure printing. (2) Divided according to the printed substrate, there are paper printing, plastic printing, cloth and textile printing, ceramic glass printing and so on. (3) According to the printing plate classification, gravure printing called gravure printing is used. The scribe line portion of the pattern roller and the text on the surface of the roller is concaver than that of the non-dash line. The ink is filled in the concave hole and passed through the rubber roller pair. The substrate is pressed heavily by the mass, and the ink is adhered from the recessed eye and adhered to the surface of the substrate. Therefore gravure printing can only print some soft and non-rigid substrates, such as paper, plastic film and so on. For some rigid, non-flexible and elastic materials are not suitable, such as rigid PVC plastic pipe, plate, sheet metal and other inappropriate. Printing using a relief printed with a scribe line protruding from a non-scribed portion is called relief printing. Letterpress has two major categories: metal relief and flexo. The metal letterpress mainly prints paper, and the flexible letterpress can print materials such as plastic films and flowers, and can also be printed on hard plastic sheets, pipes, and metal sheet pipes. The stencil is a kind of printing that is widely used. It is a stencil that can leak through ink instead of marking ink. Wire mesh can be used wire mesh, polyester mesh can also be used. Due to the flexibility of the stencils, screen printing is widely used for printing on hard plastic containers, plastic profiles, plates, pipes, metal plates, pipes, and a wide range of materials such as clothes, leather, plastic products, and films. Lithography is that the scribed portion and the non-scribed portion are in the same horizontal plane, and that the scribed portion is a material that is ink-philic, and the non-scribed portion is different from the ink-based material. The main use of printing is paper printing. (4) According to the classification of printing machinery, the printing presses can be divided into three categories: flat presses, round presses and round presses (also called rotary presses). The flattening press is the oldest type of printer. The print is flat, and the imprinting equipment is also flat. It is placed in the printed substrate once per print, coated with ink, and then plated and embossed by machine parts. The substrate is embossed once and it is slow. The flattening printing press of the circle, the edition is flat, and the embossing machine is round, the speed is flatter than flat, the present flatbed paper printing press is mostly this kind of printing machine. Circular presses are the most advanced printing machines at present. The print is a circular roll, and the embossing machine is also round. The ink is passed between the roll and the embossing roll after it is rolled on the roll. Got printed. The platen roll can be gravure, it can also be relief plate, lithography, etc. The printing machine is equipped with an automatic version of the computer system. After the ink automatically adjusts the viscosity system and other automatic instruments and meters, the normal printing speed can be up to 150-180m/min, and various kinds of printing can be done. Exquisite album.

Second, the color and light of the object The colors of the objects we see are the colors of light reflected by the reflected light after the sunlight hits the object. After passing the sunlight through the three-lens lens, various colors in the light can be caused. Different wavelengths of light and different refraction, the sun's white light is refracted into a regular arrangement of various colors of light, the order of its arrangement is red, orange, yellow, green, blue, blue, purple, various color light wavelength and primary light wavelength The range is shown in Table 26-1.

Table 26-1 Wavelength range of various color lights and wavelength range of primary color light

All objects, according to the optical characteristics can be divided into two categories of light and light body. The color of the luminous body depends on the spectral component emitted by the luminous body and directly gives the human eye a sense of color. Common luminous bodies are the sun and various illumination sources. The photoreceptor itself cannot emit light energy, but it can reflect or transmit the light projected on its surface. There are no fully transmitted or totally reflected objects in nature. Any object transmits or reflects some wavelengths of color light more or less. Some wavelengths absorb more, and reflections are less. Some, on the contrary, this difference in absorption degree is called selective absorption. Selective absorption determines the color of the photoreceptor. When white light is irradiated on the photoreceptor, selective absorption occurs. At this time, the light reflected or transmitted by the photoreceptor is not only reduced in brightness but also changed in spectral components compared to the projected light. Then there is white light, but colored light that is reflected or transmitted by the light body. According to the difference in reflectance, absorption, and transmission properties of the photoreceptor, the photoreceptor can be classified into a transparent body, a translucent body, and an opaque body. The color of a transparent body is determined by the spectral composition through it. The color of the opaque body is determined by the reflectance spectrum of the photoreceptor. The color of the object depends on the spectral color of the reflection or transmission.
Light source color and ambient color have a great influence on the color of the object. The same photoreceptor is illuminated with a different light source and will appear in different colors. If the yellow paper under sunlight is viewed under incandescent light, it will become orange; the white paper under sunlight will be viewed under red light, and the white paper will appear red. Explain that the color of the object changes with the spectral composition. Generally speaking, the color of the object is the color under sunlight, which is called the inherent color of the object. In the color image reproduction, the light source is xenon lamp, short arc xenon lamp, carbon lamp lamp, pulse xenon lamp, bromine tungsten lamp, and the spectral energy distribution is different.
Ambient color also has a profound effect on the inherent color of the object. The degree of influence depends on the strength of the ambient color. In general, the color is deep and the volume is large. The ambient color generated by a nearby object has a greater influence and the environment color is stronger.

Third, the three attributes of color The objective world of various colors can be summarized into two categories: achromatic and color. Achromatism is the amount by which an object absorbs and reflects light of various colors, and does not change the amount of absorption or reflection due to a difference in wavelength. That is to say, an object selectively absorbs or reflects different wavelengths of different colors of light. Achromatic color, achromatic color is a continuous tone of white-black stepless change. White is the light emitted by an object with 100% reflection from a white light source on the surface of the object, while black is the light source with 100% absorption from the light source. If it is not 100% full absorption or total reflection, it becomes gray. The color tone means that the object irradiates light rays from the sun and selectively absorbs or reflects part of the wavelength spectrum of white light and becomes a colored body.
1. Hue Hue is the first attribute of color, which is the naming of colors. According to the international illumination organization, the wavelengths of the three primary colors of colored light are red light 700 nm, green light 546.7 nm, and blue light 435.8 nm. Our human eye can distinguish about 180 shades of color. Hue only relates to the wavelength composition in the light reflected by the object. The addition of three primary colors equal light can become white light. Red light + green light = yellow light, green light + blue light = blue light, blue light + red light = magenta. The above is the addition of the same amount of color light, and if it is not the same amount, it can have various colors of different colors of light.
2. Brightness Lightness is the degree of visual lightness that occurs when a color light acts on the human eye. The greater the amount of color light transmitted and reflected, the higher the lightness of the colored light, and the brightness is also called brightness. The brightness of the color photoreceptor depends on the illumination of the photoreceptor by the light source and the ability of the photoreceptor itself to reflect and transmit. The stronger the reflection or transmission of the photoreceptor, the greater the lightness. For the same hue, the greater the lightness, the lighter the color. The hue and lightness of different hue are different. The yellow light has a higher lightness, second only to white, the lightness of blue and purple is lower, and the red and green light are between yellow and blue lightness. Achromatism has only lightness and no distinction between hue and saturation (ie, purity or saturation). The whiteness of white is the highest in achromatism, the blackness is the lowest in black, and the gray is in the middle of the lightness between black and white.
3. Saturation (ie, purity or saturation)
Chromaticity of color refers to the degree of selectivity of objects through or reflected light, that is, the purity of the color. The object is more selective in the reflection or transmission of light, and the narrower the wavelength range of the reflected or transmitted color light wave, the higher the purity and the higher the chroma. The maximum monochromatic brilliance in the spectrum, the closer the hue to monochromatic light, the greater the chroma. The achromatic degree of chromaticity is equal to zero, and the more color components contained in the color light, the smaller the chroma. The high color light gives a bright and pure feeling, and the low chroma gives people a feeling of dullness. Among the shades of light, the red chroma is the highest, the green chroma is the lowest, and the rest is between red and green.
When the brightness is low or the chroma is low, it is also very difficult to determine the hue. The lightness is moderate, and the chroma is the greatest; the lightness is too large or too small, and the chroma is significantly reduced.
According to the basic theory of color vision, the saturation of color depends on the intensity of the three primary colors of the optic nerve in the work, green, and blue, as well as the difference between the strongest and weakest of the three light stimuli.

Fourth, the color of the mixture of two or more than two kinds of color light or pigment mixed to produce a new color process called color mixing. The color mixture of colored light additive color mixing and color subtractive color mixing two, the color forming principle of these two methods is somewhat different.
1. Additive color mixing