Why is the stage beam light color cast phenomenon?

- Dec 01, 2018 -

Because the modern stage beam light source is a projection high-pressure mercury lamp product, that is, the lamp light source adopts the integrated design of the bulb and the reflective cup, the luminous focal length is basically controlled within the range of 31-41mm, and the bulb illumination focusing arc is ultra-short, commonly known as "point source". . The advantages of this type of beam lamp are small size, light weight, low power, high light efficiency, fast rotation reaction speed, and strong spatial shape on the stage; the disadvantage is that the lamp is highly focused, the spot is small, and the light distribution area is small. Because the focal length of the bulb is very short, when the luminaire is loaded with color, the glare portion of the bulb will be reflected back to the center of the bulb and the ball through the vertical direction of the color patch, causing secondary heating of the bulb filament, the center of the ball, and the molybdenum sheet. It will seriously affect the service life of the lamp, and even the use of the lamp is poor.

In response to this problem, many of the most experienced luminaire manufacturers preferred to install the color filter obliquely. When Xiaobian was aware of it, it was inadvertently found that many luminaire manufacturers also applied for patents for this technology (in the order of application time as follows: Color wheel lighting patent number 201110433066.6 color wheel of stage lamp, lamp applying the color plate and control method of the lamp; Shenglong lighting patent number 201220366890.4 bending type color disk; Haoyang electronic patent number 201220224992.2 a stage lamp color wheel device ; Pearl River Light Patent No. 201210289242.8 Stage Light Filter Unit), this technology is to form a 10-12° angle between the luminaire filter and the horizontal direction of the bulb installation, so as to avoid the direct light of the bulb from being reflected back through the color film. The bulb center and the welding wire of the filament, the lamp rod molybdenum sheet, etc., together with the heat dissipation fan of the bulb, can effectively control the temperature of the filament and the molybdenum sheet to within 350 ° C when the color filter is added, to ensure the service life of the bulb and Normal use.

This technology has been widely promoted in the stage beam lamp, but the problem has come again. After the lamp color film is tilted by 10-12°, when the color film is used in the wide-angle prism, the color cast phenomenon will appear carefully, especially in the use of orange, yellow, etc. When the color film is similar, the green spot will appear. The reason is that because the color film is tilted, the tilt angle of the color film makes the color film itself have a transition color, and then the colorful refraction principle and the spot angle of the wide-angle prism are added. The enlargement of the transitional color source is magnified, and the color cast light and shadow are mixed on the surface. This is really "fish and bear's paw can not have both", the lamp to ensure the life of the bulb, but can not guarantee the purity of the color, to ensure the purity of the color but can not guarantee the normal life of the bulb.

The reason is found out, is there a better solution?

We have analyzed through too many experiments and tests from the technical level. At present, there is no such thing. If there is, there must be trade-offs or compromises to find a way that is not the best of both worlds. Now share as follows:

The prerequisite for improvement is to ensure color purity:

Experimental method 1: cancel the tilt angle of the color film, install the color film in flat, and apply a high-temperature white protective layer on the front end of the bulb pole. This way, the connection of the bulb molybdenum should not exceed 400 °C, but important things should be reminded again. This will be much better than before, but there is still a temperature distance from 350 °C. If the temperature is too high, the oxidation speed of the molybdenum sheet will be accelerated, the service life of the bulb will be shortened, the life of the bulb will not be guaranteed, and the cost of use will increase. The bulb is equivalent to the value of a half lamp. Maybe you will say that it is not enough to directly control to within 350 °C? If anyone has this technology, don't share this article, because the reflected light of the color film can make the temperature of the bulb molybdenum rise sharply above 200 °C to about 500 °C, and the flat color film can be reduced to 400 °C. The technology is already very good.

Experimental method 2: On the basis of the method 1, the change can be made in the software control of the luminaire, that is, when the color film partially reflecting the infrared light is cut in, the power of the bulb is appropriately reduced, and the result is that the temperature of the bulb is guaranteed. Maybe this is a good choice, but the color of the light will be sacrificed when the light is cut into the color. You will find that the brightness of the light bulb changes when the color is switched, and the white protective layer on the light bulb can reach the normal life of the light bulb. Time, now the top-level bulb manufacturers are not fully grasped, because the protective layer is added, "neither the birth nor the original", once the change is made, the white protective layer must be added when replacing the new bulb. But unfortunately, the original bulbs of most bulb manufacturers have not added this white protective layer so far.

Experimental method 3: The light color film is flat-mounted, and the light bulb does not need to be white protective layer, that is, a high-temperature resistant circular metal light blocking sheet is added at the center of the light path between the light bulb and the color film, so that the vertical reflection of the center position of the color film can be effectively blocked. Light, the test proves that the bulb temperature problem is solved, and there is no need to worry about the life of the bulb, but there are many new problems. When testing, it is found that each pattern of the lamp has a black shadow when the wide-angle prism is used, and some colors still have reflection. The gray shadow, tossed for so long, still failed to solve the problem of color purity, it seems that we still need to continue to work hard!

The above solutions only need to share, the problem that fish and bear's paw can't have both, and whether the high-ranking people have different opinions. A strong R&D institution or a modified enthusiast can try more. Warranty products are strongly not recommended for personal modification, and damage caused by private modification will not be guaranteed by the manufacturer. After all, "radish cabbage has its own love", a lamp involves many fields such as light source, optics, dynamics, program system and many other fields, the product is only perfect and not perfect!


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