DRL lamps

DRL lamps are high-pressure fluorescent mercury discharge lamps with corrected color reproduction. Do not be mistaken, relying on the definition. The color rendition of DRL lamps is not too decent.

History of

Historically, low-pressure lamps were the first to emerge, where discharge occurred in sodium vapor. This implies not the process of the invention, but the industrial development of lighting devices. Speaking, to summarize, the commercial sense of using discharge lamps for illumination brought to the industry by Peter Cooper Hewitt. And it happened in 1901.With the filling of mercury, the lamps seemed so successful to the creator that a researcher in the new year organized a company with the support of George Westinghouse. The enterprises of the latter were engaged in production.

The step seems logical for the simple reason that George Westinghouse together with Tesla fought for the introduction of alternating current. And he was happy with each individual invention, for which the mentioned kind of electricity was required. The sodium lamp appeared in 1919, thanks to the efforts of Arthur Compton. A year later, borosilicate glass was added to the structure. Characterized by a low coefficient of thermal expansion, it is excellent in resisting the aggressive environment of sodium vapor. The practical use of lamps on the streets of the city dates back to the early 30s( in the Netherlands - from July 1, 1932).

The power of the luminous flux of sodium lamps was 50 lm / W, which was considered a worthy indicator. Despite the specific yellow-orange color of the radiation. In the USSR, the development of low-pressure sodium lamps did not go. Mercury found more acceptable. In addition, high pressure sodium lamps appeared. The described models are characterized by incorrect color rendering. The foregoing concerns living objects and man. The deficit was partially overcome in 1938, by introducing low-pressure mercury lamps into industrial production. Key Features:

1. Light Return - 85 - 104 lm / W.
2. Service life - up to 60 thousand hours.
3. Promising emission spectrum.

DRL lamps appeared in the early 50s. Their operational characteristics do not reach the values ​​given above( return 45–65 lm / W, service life 10–20 thousand hours), but are acceptable. DRL lamps are used for outdoor and indoor lighting. The next step in the development of discharge lamps became RLVI( high intensity).The key difference was increased efficiency. In the first samples, the indicator was already 100 lm / W.High pressure sodium lamps are superior in performance models DRL.

Features of the discharge lamp with corrected color rendering

Lamp brightness

Above it was said that individual discharge( and fluorescent) lamps are characterized by low color rendering. The world around us is becoming slightly distorted, which quickly tires the psyche. An additional factor is the physiological sensitivity of the eyes. It is not identical in the visible spectrum, some people are able to see the aura. But for most individuals, the maximum susceptibility falls on the 555 nm wavelength( green).And towards the edges, the sensitivity of the eyes decreases.

Therefore, researchers urge to carry out adjustment of the power of the lamps on the physiological characteristics of a person. As a result, 1 W at a wavelength of 555 nm is equivalent to 10 - at 700 nm. Infrared radiation is not perceived by man. Evaluation of brightness produced by the light flux, taking into account the effects of each wavelength. The unit of measurement of the magnitude was the lumen, equivalent to the power of 1/683 W for a wavelength of 555 nm. A light output( lm / W) shows how much of the power in the light bulb becomes optical radiation. The maximum value reaches 683 lm / W and is noted exclusively at the wave of 555 nm.

You can not ignore the unit of illumination - luxury. Numerically equal to 1 lm / sq.m. Knowing the luminous flux, the height of the lamp, the angle of its opening, it is possible to calculate the illumination. The parameter for rooms is normalized according to GOST.In light of the above, it is clear why DRL lamps with corrected color rendition are still found on the market, despite the relatively unenviable characteristics.

A locus is used to evaluate color rendering. This is a figure resembling an inverted parabola, slightly littered on its left side. In it, the color shows two coordinates from 0 to 1. In order for the lamp to exhibit good color rendition, the position of its integral radiation tends to the center of the locus. We add that the increase in color temperature will mix the spectrum from red to violet:

• 2880 - 3200 K - warm yellow;
• 3500 K - neutral white;
• 4100 K - cold white;
• 5500 - 7000 K - daylight.

In this regard, low-pressure yellow-orange sodium lamps are considered a bad choice. From them, a chemical imbalance in the retina causes fatigue. However, remember that the spectrum, not the color temperature, plays the decisive role: any light bulb is inferior to the Sun. Therefore, in the poor spectrum of a low-pressure sodium lamp( two spectrin in the yellow region), the objects look black, gray, or yellow. This is called incorrect color rendering.

The parameter is adopted to be characterized by an index on the basis of a visual comparison of the samples illuminated by the bulb with the standard. The value fits in the range from 1( worst version) to 100( ideal).In practice, the maximum is possible to find a lamp in the range of 95 - 98. This will help you choose the DRL lamp on the counter( a typical value of 40 - 70).

Correction of color rendition

Discharge smolders in the environment of ionized gas. The whole principle of action. The rest is reduced to the conditions for obtaining the arc between the electrodes. Ionization conditions require overvoltage, which is no longer needed. Often, discharge lamps require a control device. The atmosphere is filled with inert gas and a small amount of elastic metal vapor( mercury, sodium, their halides).In the practice of lamps, the following types of discharges are mainly used:

1. Smoldering - with a low current density with low pressure of gas or vapor. The voltage drop across the cathode reaches 400 V. The dark spots in the cathode area are visually visible.
2. Arc - with high current density at different pressures. The voltage drop across the cathode is relatively small( up to 15 V).The low pressure arc column is similar to a glow.
3. High intensity arcs are a specific phenomenon used in projectors. For example, they were used to identify enemy air objects during the Second World War. It is based on a special mode of operation of the coal rod, opened in 1910 by G. Beck.

The spectrum of the mercury discharge lies in the ultraviolet region by 40%.The phosphor converts this area into a red glow, at the same time most of the violet and blue parts pass freely. The quality of the correction of the spectrum is determined by the red ratio( it increases with increasing layer thickness, as well as the price, the necessary parameters are determined experimentally due to the complexity of the calculation).Quartz-glass mercury burner( does not emit gaseous substances during operation), and the external flask, coated with phosphor from the inside, is from the usual, but refractory. Edisonovsky base. Europium-activated yttrium phosphate-vanadate is used as a phosphor. Material detects the emission spectrum of the four red bands: 535, 590, 618( max), 650 nm. The optimum mode of operation is achieved at a temperature of from 250 to 300 degrees( the exit time is about a quarter of an hour).

Before applying the phosphor is ground and calcined. Yttrium phosphate-vanadate is chosen for a reason, it perfectly withstands processing. Considerable cost is often compensated by the joint use with other materials. For example, strontium-zinc orthophosphate. They better absorb the wavelength of 365 nm, it is possible to achieve acceptable performance( taking into account the specifics of the application in the field of industrial lighting with an installation height of 3 to 5 meters).

There are known cases of use of magnesium fluoromangermanate activated by tetravalent manganese. Light efficiency and red ratio( 6-8%) at the same time slightly reduced. The optimum temperature is set at around 300 degrees Celsius. With further heating, the effectiveness of the device falls. The material is inferior to yttrium phosphate vanadate in all indicators except the price: it absorbs part of the violet-blue region of the spectrum, detects the luminescence spectrum in the far red region( where the eye shows low sensitivity), loses brightness during processing.

The design usually provides one or two firing electrodes, the distance from which to the cathode is relatively short. So an external control gear is not required. In combination with a standard base, a convenient replacement of incandescent bulbs with an increased efficiency is obtained. In the process of operation, the flask is very hot due to the intense absorption of radiation by the phosphor. The calculation of the geometric shape is carried out on the basis of this parameter. On the one hand, it is required that the radiation of the burner should fall on the phosphor, on the other hand, the temperature in the operating mode should not exceed the optimum one( see above).

The flask is filled more often with argon. It is cheap and contributes little heat loss.10-15% of nitrogen is mixed in to increase the breakdown voltage. The total pressure is approximately atmospheric. No ingestion of oxygen( destroys metal parts) or hydrogen( increases the arc ignition voltage) is unacceptable. Any burning position is allowed, but the horizontal position is not encouraged. The arc slightly bends, quartz glass is in an unfavorable temperature mode. The temperature of the medium affects the breakdown voltage. In winter, it is more difficult to ignite an arc, mercury settles, and the process takes place in an environment of practically pure argon( for this reason, starting devices sometimes have to be used).

DRL lamps have a relatively high base. The temperature is able to cross over the boiling point of water. This is required to take into account when selecting the cartridge and chandelier( lamp) for the installation of the lamp. At a time to remember the advice of the authors of the patent on the first halogen lamps. The temperature of the burner is relatively low, but aluminum will melt easily.

Marking

In domestic practice, the figure that goes after the DRL means the power consumption in watts. Then the red ratio follows: the ratio of the red flow( from 600 to 780 nm) to the total is expressed as a percentage. The hyphen is the development number. Red ratio characterizes color reproduction, good values ​​are considered to be higher than ten.

According to the international standard IEC 1231, the ILCOS system is used. These are competitors of the German labeling LBS and the all-European ZVEI.The market is full of confusion. According to ILCOS:

1. QE refers to the ellipsoidal shape of the bulb.
2. QR designates a flask with an inner reflective layer, mushroom.
3. QG denotes a spherical flask.
4. QB designates products with integrated ballast.
5. QBR refers to products with integrated ballast and reflective layer.

Philips has its own way of looking at things, but General Electric doesn't want to hear about both. Actually, it is better to focus on reference books, or read the information on the package. Remember that the base is standard and other sizes. The share of production of DRL lamps is continuously decreasing, so it makes no sense to study complex notation in too much detail. And taking into account the entry into the LED market, it is better to find something modern and constantly developing for the home and country. As for efficiency, the dispute is clearly not in favor of discharge lamps, although for some time they have successfully precipitated a filament.