Plate-making common light source

The light source is one of the important equipments in the process of pre-press plate making. Electronic color separation, photo-distribution output, direct plate-making machine and earlier photo-production

The equipment is operated by light, either directly or indirectly, based on light-sensitive materials. The light source used in the plate making, in the spectrum, energy

The temperature, uniformity, radiation and other characteristics have very high requirements, and the type of plate-making light source is more, the following introduces several commonly used light source

.

A lighting source

1. Incandescent lamp. The incandescent lamp is a kind of heat radiation light source. The tungsten wire is heated to the incandescent state by the electric energy and emits light. The higher the operating temperature of the filament,

The brighter the light is. Incandescent light is a continuous spectrum of light, which has good color rendering, high color rendering coefficient, simple structure, convenient use, but luminous efficiency

Low, low power, low color temperature (2400~3400k), less blue-violet light components. Incandescent lamps are generally used for lighting, but also change the incandescent glass

After the color is used in the darkroom, few incandescent lamps are used for plate making.

2. Fluorescent lamp. Also known as fluorescent lights. Fluorescent lamps for general lighting, filled with argon and mercury in the tube, using the Penning effect of argon mercury gas, making the lamp point

Bright light. The brightness of the fluorescent lamp is gentle, the average life is 3,000 hours, the color temperature is 6500k, and the color rendering coefficient is 70. Due to its poor color rendering, the object to be illuminated

The color is distorted, so it is not suitable for printing plates, and the high color rendering fluorescent lamp is a printing standard light source after the ordinary fluorescent lamp, which overcomes the ordinary

The disadvantages of fluorescent lamps are consistent with the colors of natural colors and are therefore widely used.

3. Infrared light. The infrared lamp is also a kind of heat radiation source, which is longer than incandescent filament filament water supply / dampening, color temperature below 2500k. Infrared

The line lamp has less visible light than incandescent lamps of the same power and has a darker visual appearance. It is often used for electric infrared photography.

Second, electric light source

Tungsten halogen lamps. Tungsten halogen lamps, also known as halogen lamps, utilize tungsten halides for tungsten lamp cycles in light bulbs. In certain

Tungsten evaporates at temperatures near the wall of the bubble and acts as a halogen to form a gaseous tungsten-halide compound that decomposes into tungsten when it diffuses into the hotter filament area.

Halogen and tungsten are re-deposited on the tungsten filaments, and the halogens diffuse into the colder wall region and combine with tungsten.

Tungsten halogen lamps have all the characteristics of incandescent lamps, small volume, light flux and spectrum stability, color temperature 3400k, higher light efficiency than incandescent lamps. point

Tungsten halogen lamp requires only a general power supply, convenient, low cost, more commonly used in the extension, such as 12v 55w halogen lamp for sg-737

Electric extensions, 12v 50w for dc3000 series extensions, and newer 6.6a 100w halogen lamps for tango series extensions,

Tungsten halogen lamps are also used as light sources for various densitometer measuring heads.

Third, proof printing with light source

1. Fluorescent lamp

The structure of the fluorescent lamp is the same as that of the fluorescent lamp, but the inside of the tube is a bismuth-activated blue light-emitting pyrophosphate. The wavelength of the emitted spectrum is 380 to 540 nm.

During the printing process, the commonly used flat and gravure polyvinyl alcohol (pva) dichromate sensitized film absorbs in the ultraviolet range of 300-400nm wavelength.

Strong ability to receive; ps version of the resin sensitizer in the 300 ~ 450nm wavelength range has a strong absorption capacity, so the use of printing fluorescent lamp is more appropriate, with

When the fluorescent lamp is a cold light source, compared with the heat source, it has a high luminous efficiency and consumes less power.

2. Metal halide lamps

Metal halide lamps, also known as metal halide lamps, are made by adding metal halides to high-pressure mercury lamps and achieve high values ​​in the required wavelength range.

Radiation, thereby enhancing color rendering and efficacy, commonly used iodine and xenon lamps.

Iodine lamp. The iodine deuterium lamp is made by filling a quartz glass tube with cesium iodide, a fixed quantity of mercury and a rare gas, and has tungsten electrodes at both ends. Iodine

The light of the lamp is blue-purple, consistent with the spectral sensitivity of the diazonium and dichromate sensitizers. The iodine lamp is used as a light source for printing, with high efficiency and good quality.

The penetrating power is strong in the air with high humidity, and it is not easy to degumming when developing, and thus it occupies the mainstream in the power of the printing lamp. But iodine lamps are not easy under hot conditions

Start, its life is about 500 hours, the working voltage is about 500v, the slope of the installation does not exceed ±5%, the voltage is within ±10% to ensure the work

normal.

Xenon lamp. The xenon lamp emits light using the vapor discharge of cesium iodide and thorium iodide, and the luminous efficiency reaches 80 to 90 lm/w, due to the cesium iodide in the lamp.

The ring, which has a high pressure in the center of the arc, has a discharge characteristic. The spectrum is the entire visible light, and the light area has very dense spectral lines. The spectral energy

In the visible area is average, good color rendering, color rendering coefficient 85 ~ 90, color temperature 600k, light color close to daylight, high luminous intensity, suitable for printing plate illumination

.

Fourth, phototype system with light source

The light source used in the photo-taking system is mainly a laser. Since there are hundreds of substances that make lasers, lasers can be divided according to different substances

For gases, solids, semiconductors, chemical and liquid lasers, etc., they can be divided into continuous and pulsed categories according to their working methods.

"The report", but the most commonly used are He-Ne lasers, argon-ion lasers and solid-state lasers.

HeNe laser

The helium neon laser is composed of a discharge tube, a resonant cavity and an excitation power source. The discharge tube is filled with a mixture of helium and neon, and the laser is continuously operated.

It can be excited by AC, DC, RF, etc. The excitation voltage requirement is several thousand volts and the discharge current is in the order of a few milliamps to several tens of milliamps. He-Ne laser

The main wavelengths of the device are 3390 nm, 1150 nm, and 632.8 nm. The 632.8nm laser is an exposure source for electric extensions, used for electronic screening or screen screening.

Its high energy conversion rate, simple and solid structure, good frequency stability, life expectancy of more than 1000 hours, screen company sg-737 electric extension is mining

This type of laser is used.

2. Argon ion laser

Argon ion lasers consist of discharge tubes, resonant cavities, power supplies, and magnetic fields. The discharge tube is filled with argon ions, after the laser is connected to the DC power supply

The cascaded exciter produces tens of thousands of volts DC, rapidly ionizing argon and stimulating the argon ions to produce laser light.

The output frequency of the argon ion laser is 488nm, 514.5nm and ultraviolet 351.1nm, 363.5nm. Since the argon ion laser works

Very high current (usually around 6a). Generally, a metal heat sink with good thermal conductivity is applied on the outside of the laser tube, and an exhaust device is added.

Life spans thousands of hours. For example, the linohell r3030 uses an argon ion laser.

Solid state laser

The solid-state lasers used in platemaking include ruby, yttrium aluminum garnet, yag lasers, and semiconductor lasers, among which imagesetters make

With semiconductor lasers at most, the wavelength is at 780nm, such as the screen company's dt-r3075 imagesetter is the semiconductor laser used.

Through the above analysis, we summarize the characteristics of the plate-making light source:

1. High luminous intensity;

2. The light source spectrum should be compatible with the spectral sensitivity of the photosensitive material;

3. High luminous stability;

4. The light energy distribution is good;

5. Less lines outside;

6. Not harmful to the working environment and staff;

7. Can instantly ignite;

8. The price is right;

9. Simple structure and easy maintenance.