EP0786799B1 - Lampe à incandescence avec réflecteur à spectre d'émission semblable à celui du soleil - Google Patents

Lampe à incandescence avec réflecteur à spectre d'émission semblable à celui du soleil Download PDF

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Publication number
EP0786799B1
EP0786799B1 EP19970300451 EP97300451A EP0786799B1 EP 0786799 B1 EP0786799 B1 EP 0786799B1 EP 19970300451 EP19970300451 EP 19970300451 EP 97300451 A EP97300451 A EP 97300451A EP 0786799 B1 EP0786799 B1 EP 0786799B1
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EP
European Patent Office
Prior art keywords
lamp
thickness
layer
sio
light
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19970300451
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German (de)
English (en)
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EP0786799A1 (fr
Inventor
Wilmert Cyriel Stefaan De Bosscher
Joseph Guido Marie Gielen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Flowil International Lighting Holding BV
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Flowil International Lighting Holding BV
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Publication date
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Publication of EP0786799A1 publication Critical patent/EP0786799A1/fr
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01K—ELECTRIC INCANDESCENT LAMPS
    • H01K1/00—Details
    • H01K1/26—Screens; Filters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V9/00—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters
    • F21V9/02—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters for simulating daylight

Definitions

  • the present invention relates to an incandescent reflector lamp which emits light with a spectral output that substantially simulates sunlight, at least over the visible range of the electromagnetic spectrum.
  • Incandescent daylight lamps having a blue coating are also known.
  • the blue coating results in a partial filtering of the red portion of the spectrum from the light source.
  • the spectral output has no real correlation with the spectrum of sunlight.
  • Another lamp is known from DE-A-3931950 (over which claim 1 has been characterised).
  • This lamp uses an incandescent halogen burner as the light source and incorporates a cold light reflector on its parabolic surface behind the light source.
  • the lamp further includes a separate filter, which is preferably a daylight filter made from a dichroic material, which provides a colour temperature of approximately 5600K. Although this lamp is said to produce an agreeable cool light, the filter is just a standard dichroic filter.
  • Reflector lamps are lamps which have an integral coating on the generally parabolic surface located behind the light source, usually a dichroic coating, in order to reflect light back past the light source and through the front glass.
  • the known daylight filters generally reduce the proportion of the yellow and red light being transmitted.
  • these filters are formed as dichroic coatings, they do not absorb but reflect the unwanted radiation back to the parabolic reflector, whereupon the light is reflected back again towards the front glass.
  • These secondary and multiple reflections will increase the relative amount of yellow and red light hitting the dichroic coating of the filter, which also increases the amount of yellow and red light being transmitted. To correct this, the transmission of yellow and red light must be significantly lower than the theoretical value.
  • a reflector lamp for simulating daylight comprising a front glass, a reflector, a halogen light source and a dichroic filter to filter light from the light source, characterised in that the transmission of light through the dichroic filter over the range 400 to 480 nm is not less than 90% and the value of the average transmittance in the 580 to 760 nm region subtracted from the average transmittance in the 400 to 480 nm region is greater than 70%, wherein the lamp has colour coordinates and an emission spectrum substantially the same as sunlight, the emission spectrum of the lamp having a single peaked curve with the peak laying between 450 and 580 nm and a coefficient of correlation with the spectrum of sunlight over the visible region of between 0.7 and 1.0.
  • the transmission of light through the filter of the front glass between the range of 400 and 480nm is higher, and between 580 and 700nm is lower, than the predicted values for a lamp not having a reflector. This therefore reduces the relative amount of yellow and red light being emitted and produces light from a reflector lamp whose spectral emission is closer to that of sunlight.
  • the filter produces a transmission curve that has a single broad peak with no minima between 400 and 580 nm, most preferably between 400 and 480nm.
  • the transmission of light over the range 580 to 760nm is below 25%.
  • the transmission curve exhibits a minimum between 400 and 480nm, usually at around 430nm.
  • the transmission properties of the dichroic filter can be seen therefore to be tuned to take account of secondary and multiple reflections from the reflector so that the lamp has a spectral emission substantially the same as sunlight, at least over the visible range.
  • the lamp allows a reflector to be used whilst producing a light that more closely resembles sunlight.
  • the spectral emission has a coefficient of correlation with the spectrum of sunlight over the visible region of between 0.7 and 1.0, preferably between 0.8 and 1.0, and most preferably between 0.85 and 1.0. In existing products, generally no correlation exists and in many cases the opposite tendency is found producing negative values for the correlation coefficient.
  • the spectral emission curve of the lamp closely resembles that of sunlight over the visible region having a single peak in the region between 450 and 580nm, preferably the width of the peak is narrower than that of the sunlight spectrum.
  • Medical tests have shown that the human eye can focus more easily on single peaked spectral light distributions, resulting in better vision for contrast and detail. By decreasing the width of the single peak, this effect can be increased whilst maintaining a good colour rendering index (CRI).
  • CRI colour rendering index
  • the lamp has a CRI of greater than 90%.
  • the CRI is greater than 93% and in a most preferred embodiment the CRI is equal to or greater than 95%.
  • a preferred range for the CRI is between 93 and 97%.
  • the peak of the lamp's emission spectrum is at 480 nm as this correlates well with the peak of the sunlight spectrum.
  • just having a single peaked spectrum provides advantages in its own right, because of the increase in ease with which the eye can focus.
  • the dichroic filter comprises alternating layers of ZnS and SiO 2 .
  • the filter consists of the following 8 layers:
  • the dichroic filter is a coating which is integral with the front glass of the lamp, preferably coated on the inside of the front glass.
  • the reflector lamp has a halogen light source and the dichroic filter is a coating applied to the inside surface of the front glass which consists of alternating layers of ZnS and SiO 2 .
  • This coating is preferably applied by the molybdenum boat thermal evaporation process using ZnS and SiO as evaporation materials.
  • the SiO is evaporated in a partial oxygen atmosphere to form SiO 2 layers.
  • This method is advantageous because it is considerably cheaper to use than other evaporation processes, such as the electron beam gun evaporation process, with SiO 2 and TiO 2 as evaporation materials, used by Balzers in the production of their above mentioned "TL60" filter.
  • the reflector may be a standard reflector material which reflects substantially all of the visible light incident on it back into the lamp, or it may be designed to reflect only selected wavelengths, for example, a cold light reflector which may allow infrared light to pass through.
  • the preferred light source is an incandescent halogen capsule or burner with a colour temperature of between 2700 and 3200K, for example, a 100W high volt halogen lamp or at least a 50W low volt lamp.
  • a colour temperature of between 2700 and 3200K for example, a 100W high volt halogen lamp or at least a 50W low volt lamp.
  • the emission from the lamp itself prefferably has a colour temperature higher than 5000K, while maintaining the smallest possible deviation from the black body locus of a chromaticity diagram.
  • the lamp has an emission with a colour temperature of greater than 6000K, preferably as high as 6500K, since this provides a person using the light with better conditions for reading due to improved contrast and vision.
  • the soothing properties and the improved contrast and vision can be achieved by the single peaked distribution without having such a high colour temperature, for example, 4000K.
  • a colour temperature may be produced by a high volt 50W lamp, which may be more appropriate for existing desk top fixtures which usually only allow up to a maximum of 60W.
  • the single peak of the emission curve would be at approximately 580 nm, rather than 480 nm for the 6500K version.
  • the preferred illuminance level for the lamp is between 1100 and 1700 lx, preferably between 1200 and 1650 lx, and most preferably at 1350 lx.
  • a homogeneous illumination of the work space by the lamp is important, especially if the lamp is to maximise its soothing and its improved contrast and vision properties.
  • the reflector should therefore have a large beam angle, for example, 50° or more, preferably 60° or greater for desk top applications, in order to spread the beam of desired illuminance over a reasonable area, rather than just a small spot.
  • FIG. 1 there is shown an embodiment of a preferred reflector lamp.
  • the lamp comprises a front glass 1, a reflector 2, an incandescent light source 3, often referred to as a "burner", and a socket 4.
  • the lamp has a dichroic filter 5 coated on the inside of the front glass 1.
  • the coating may be applied by any suitable technique, the preferred technique being a standard molybdenum boat thermal evaporation process using ZnS and SiO as evaporation materials.
  • the SiO is evaporated in an oxygen enriched atmosphere to form SiO 2 layers.
  • Other techniques, such as electron beam gun evaporation, may also be used although tend to be more expensive.
  • the transmission properties of the dichroic filter are tuned so that the spectral emission of the lamp is substantially the same as sunlight.
  • the lamp consists of a high voltage hard glass incandescent halogen burner 3, focused inside a parabolic reflector 2 with a rim diameter of 95mm.
  • the reflector consists of a moulded parabolic glass portion of the lamp envelope inside which a standard semi durable cold light mirror material is coated. The coating reflects visible light but is transparent to infrared.
  • a front glass 1 is glued to the reflector 2 to prevent dust and other pollutants from entering the lamp, as well as providing protection in the event of the burner 3 exploding and a UV-stop filter.
  • the front glass 1 has a coating 5 applied to its inside surface which converts the light emitted from the high voltage burner into a single peaked spectrum with a colour temperature of at least 6000K.
  • the coating 5 consists of 8 layers of alternating ZnS and SiO 2 with the following thicknesses: Layer Nr. Material Thickness (nm) 1 ZnS 76.73 2 SiO 2 110.74 3 ZnS 65.04 4 SiO 2 103.86 5 ZnS 71.59 6 SiO 2 118.81 7 ZnS 102.94 8 SiO 2 80.38
  • the transmission properties of this coating 5 are shown in Figure 6.
  • the coating 5 in this example achieves a colour temperature conversion of 2800K to between 6000 to 6500K when used with a 100W, high volt light source or at least a 50W low volt light source.
  • the spectral outputs of the different curves when compared to that of the sun correlate as follows: light source correlation coefficient sun 1.00 preferred embodiment of the present invention 0.86 halogen lamp -0.51 neodymium containing lamp -0.42 blue coated incandescent daylight lamp -0.53 fluorescent daylight lamp 0.40
  • Figure 3 in addition to clearly showing that the single peaked spectral emission of the preferred lamp closely matches that of sunlight, also shows that there is improved kurtosis, ie. sharpness of the peak. This allows for easier focusing of the human eye whilst maintaining the high colour rendering index.
  • the filters exhibit transmission minima between approximately 420 to 430nm.
  • the preferred filter has a transmission curve that exhibits a single broad peak in the blue region that spans between about 400 and 500nm.
  • the preferred filter also shows lower transmission in the yellow and red region of the spectrum compared to the Balzer's "TL60" daylight filter shown in Figure 4.
  • the reflector 2 may be of any type, eg. smooth, faceted etc, and its transmission properties may be dictated by the heat resisting properties of the socket 4 and/or the light fitting (not shown).
  • the lamp may, for example, be a 75W lamp with a 25° spread angle for ceiling mount applications, or perhaps a 50W lamp with a 50° spread angle or a 50mm diameter, 50W lamp with a 60° spread angle for desk lamp applications. In all these cases, it may be necessary to adjust the coating or filter in order to compensate for the different colour temperatures of the burners and for the different secondary and multiple reflections of the various reflector types.
  • a lamp which does not require a complex construction or extra parts to hold a filter; which in its most preferred embodiment has improved daylight reproducing abilities; and which can provide a soothing light that enables optimal contrast and homogeneous illumination of a reading surface.

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Optical Filters (AREA)

Claims (15)

  1. Lampe à réflecteur simulant la lumière du jour comprenant une dalle frontale (1), un réflecteur (2), une source de lumière à halogène (3) et un filtre dichroïque (5) pour filtrer la source de lumière,
       caractérisée en ce que
    la transmission de la lumière à travers le filtre dichroïque (5) sur la plage des 400 à 480 nm n'est pas inférieure à 90 % et que la valeur de la transmittance moyenne sur la plage des 580 à 760 nm, soustraite de la transmittance moyenne dans la région des 400 à 480 nm est supérieure à 70 %, et dans laquelle la lampe a des coordonnées de couleur et un spectre d'émission substantiellement identiques à la lumière du soleil, le spectre d'émission de la lampe présentant une courbe à crête unique se situant entre 450 et 580 nm et un coefficient de corrélation avec le spectre de la lumière du soleil sur la région visible comprise entre 0,7 et 1,0.
  2. Lampe selon la revendication 1, dans laquelle le filtre dichroïque (5) est appliqué sur la dalle frontale (1) de la lampe.
  3. Lampe selon la revendication 1 ou 2, dans laquelle la lampe présente une température de couleur supérieure à 5000 ° K.
  4. Lampe selon la revendication 3, dans laquelle la lampe présente une température de couleur supérieure à 6000 ° K.
  5. Lampe selon l'une quelconque des revendications précédentes, dans laquelle la crête du spectre d'émission est à 480 nm.
  6. Lampe selon la revendication 1 ou 2, dans laquelle la lampe présente une température de couleur de 4000 ° K et la crête du spectre d'émission est à 580 nm.
  7. Lampe selon l'une quelconque des revendications précédentes, dans laquelle la transmission de la lumière à travers le filtre dichroïque (5) sur la plage des 580 à 760 nm est inférieure à 25 %.
  8. Lampe selon l'une quelconque des revendications précédentes, dans laquelle le filtre dichroïque (5) détermine une courbe de transmission n'ayant qu'une crête unique large, sans minimum présent sur la plage des 400 à 580 nm.
  9. Lampe selon la revendication 8, dans laquelle la crête de la courbe de transmission s'étend entre 400 et 480 nm.
  10. Lampe selon l'une quelconque des revendications précédentes, dans laquelle les coordonnées de couleur de la lampe répondent à : 0,310 < x < 0,350 0,320 < y < 0,360
  11. Lampe selon l'une quelconque des revendications précédentes, dans laquelle la lampe a un indice de rendu des couleurs supérieur à 90 %.
  12. Lampe selon la revendication 11, dans laquelle l'indice de rendu des couleurs n'est pas inférieur à 95 %.
  13. Lampe selon l'une quelconque des revendications précédentes, dans laquelle le filtre dichroïque (5) comporte des couches alternées de ZnS et de SiO2.
  14. Lampe selon la revendication 13, dans laquelle le filtre dichroïque (5) comporte au moins 8 couches.
  15. Lampe selon la revendication 14, dans laquelle le filtre dichroïque (5) comprend les huit couches suivantes :
    couche 1 ZnS 76,73 nm d'épaisseur
    couche 2 SiO2 110,74 nm d'épaisseur
    couche 3 ZnS 65,04 nm d'épaisseur
    couche 4 SiO2 103,86 nm d'épaisseur
    couche 5 ZnS 71,59 nm d'épaisseur
    couche 6 SiO2 118,81 nm d'épaisseur
    couche 7 ZnS 102,94 nm d'épaisseur
    couche 8 SiO2 80,38 nm d'épaisseur
EP19970300451 1996-01-24 1997-01-24 Lampe à incandescence avec réflecteur à spectre d'émission semblable à celui du soleil Expired - Lifetime EP0786799B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9601402.2A GB9601402D0 (en) 1996-01-24 1996-01-24 Incandescent reflector lamp with sun-like spectral output
GB9601402 1996-01-24

Publications (2)

Publication Number Publication Date
EP0786799A1 EP0786799A1 (fr) 1997-07-30
EP0786799B1 true EP0786799B1 (fr) 2002-04-10

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Application Number Title Priority Date Filing Date
EP19970300451 Expired - Lifetime EP0786799B1 (fr) 1996-01-24 1997-01-24 Lampe à incandescence avec réflecteur à spectre d'émission semblable à celui du soleil

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EP (1) EP0786799B1 (fr)
DE (1) DE69711734T2 (fr)
GB (1) GB9601402D0 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5666017A (en) * 1994-03-22 1997-09-09 Tailored Lighting Inc. Daylight lamp
US6633110B2 (en) * 1994-03-22 2003-10-14 Tailored Lighting Inc. Underwater lamp
DE102012009581A1 (de) 2011-05-15 2012-11-15 Julia von Chamier Verfahren und Vorrichtung zur Beleuchtung von Räumen
CN102352970B (zh) * 2011-08-09 2015-07-22 中山大学 一种led光源及其照明装置

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2831966A (en) * 1954-04-19 1958-04-22 Analite Corp Lighting fixtures
US4125775A (en) * 1977-10-05 1978-11-14 Corning Glass Works Solar simulator
SU1008170A1 (ru) * 1981-10-12 1983-03-30 Государственный научно-исследовательский институт стекла Стекло дл светофильтров
DE3931950A1 (de) * 1989-09-25 1991-04-04 Alexander Kaiser Leuchte
JPH0821785A (ja) * 1994-07-08 1996-01-23 Mitsubishi Heavy Ind Ltd 日射装置

Also Published As

Publication number Publication date
GB9601402D0 (en) 1996-03-27
DE69711734D1 (de) 2002-05-16
DE69711734T2 (de) 2002-11-14
EP0786799A1 (fr) 1997-07-30

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