United States Patent r191
`van Kemenade et al.
`
`[111 Patent Number:
`[45] Date of Patent:
`
`4,727,283
`Feb. 23, 1988
`
`[54] LOW-PRESSURE MERCURY VAPOUR
`DISCHARGE LAMP
`
`[75]
`
`Inventors: Johannes T. C. van Kemenade;
`Gerardus H. M. Siebers; Jean J.
`Heunlmans; Johannes T. W. deHair,
`all of Eindhoven; Johannes W. ter
`Vrugt, Geldrop, all of Netherlands
`
`[73] Assignee: U.S. Philips Corporation, New York,
`N.Y.
`
`[21] Appl. No.: 883,186
`
`(22] Filed:
`
`Jul. 8, 1986
`
`Foreign Application Priority Data
`(30]
`Jul. IS, 1985 [NL] Netherlands ......................... 8502025
`
`Int. CI.• .............................................. H0lJ 61/46
`[51]
`[52] U.S. 0. .............................. 313/487; 252/301.4 R
`(58] Field of Search ................ 252/301.4 R, 582, 584,
`252/586, 301.4 P; 313/483, 486, 487, 485;
`315/57
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`3,937,998 2/1976 Verstegen et al. .................. 313/ 487
`4,024,070 S/1977 Schuil ........................... 252/301.4 R
`4,177,401 12/1979 Yamane et al ...................... 313/485
`4,314,910 2/1982 Barnes .......................... 252/301.4 R
`4,383,200 5/1983 Van Zen et al ...................... 315/57
`4,447,756 5/1984 Kohmoto et al. ................... 313/ 487
`4,559,470 12/1985 Murakami et al ................... 313/ 485
`Primary Examiner-David K. Moore
`Assistant Examiner-Mark R. Powell
`Attorney, Agent, or Firm-John C. Fox
`ABSTRACT
`(57]
`· A low-pressure mercury vapor discharge lamp with a
`luminescent layer whose emission mainly lies in three
`spectral ranges and whose loading amounts to at least
`500 W per m2 surface area •of the luminescent layer, is
`characterized by having an absorption layer o( a lumi(cid:173)
`nescent aluminate activated by trivalent cerium and
`having a garnet crystal structure. The absorption layer
`permits the obtaining of low color temperatures (down
`to 2000 K.).
`
`18 Claims, 2 Drawing Figures
`
`5
`
`2
`
`(cid:47)(cid:50)(cid:58)(cid:40)(cid:54) 1029, Page 1
`VIZIO Ex. 1029 Page 0001
`
`

`

`U.S. Patent
`
`Feb.23, 1988
`
`4,727,283
`
`5
`
`I
`I 4
`I
`
`, / l
`I
`
`I
`I
`I 3
`
`5
`
`g
`
`2
`
`2
`
`5
`
`8
`
`7
`
`FIG.1
`
`FIG.2
`
`(cid:47)(cid:50)(cid:58)(cid:40)(cid:54) 1029, Page 2
`VIZIO Ex. 1029 Page 0002
`
`

`

`1
`
`4,727,283
`
`2
`Three-band fluorescent lamps of the kind mentioned
`in the opening paragraph are known, for example, from
`U.S. Pat. Nos. 4,335,330; 4,199,708; and 4,374,340, and
`are generally of very compact construction and in-
`BACKGROUND OF THE INVENTION
`5 tended to replace incandescent lamps. Due to their
`compact construction, the luminescent layer in these
`The invention relates to a low-pressure mercury va-
`lamps is heavily loaded, that is to say, the power con-
`pour discharge lamp, whose emission mainly lies in
`sumed by the column during operation of the lamp is at
`three spectral ranges and of which the colour tempera-
`least 500 w per ml of surface area of the luminescent
`ture of the emitted light lies in the range of 2000-3ooo lO layer. This is considerably higher than the load of the
`K., this lamp being provided with a gas-tight discharge
`luminescent lamp layer in the aforementioned lamps
`envelope transparent to radiation and having a gas fill-
`having an inner diameter of about 36 and 24 mm, re-
`ing comprising mercury and a rare gas and with a lumi-
`spectively, which load has a value of the order of 300
`ncscent layer comprising luminescent materials whose
`and 400 W /m2, respectively. It has been found that in
`emission mainly lies in the range of 590-6JO nm and in 15 these heavily loaded lamps the relative contnbution of
`the range of 520-565 nm, whilst further means arc pro-
`the blue mercury radiation is even higher, and that such
`vi~ed for maintaining a column discharge in t~e gas
`lamps without a blue luminescing material have a col-
`filling, the power consumed by the c?lumn being at
`our temperature of the emitted light of at least about
`least 500 W /m1 surface area of the lu~esccnt layer.
`2700 K. at colour points lying on the line of the black
`Low-pr~ure ~ere~ . vapour discharge lamps, 20 body radiators. As a result of this, and also of their high
`whose e1111SS1on mainly lies m three spectral ranges, also
`R(a, 8), these lamps are suitable to replace incandescent
`designated as three-band fluorescent lamps, are known
`lamps.
`from U.S. Pat. No. 4,176,294 and from Netherlands
`Hitherto, incandescent lamps have been mainly used
`Patent Specification No. 164,697. These lamps are com•
`for interior illumination. With a view to saving energy,
`monly used in general illumination and have the adv~- 25 it is often desirable to replace incandescent lamps with
`tage that they have both a good general colour rendi-
`fluorescent lamps. A typical value of the colour temper-
`tion (colour rendition index R(a, 8) of at least 80) and a
`ature of an incandescent lamp is 2650 K. However, the
`high luminous efficacy (up to values of-~ lm/W and
`use of colour lamps (for example the so-called flame
`higher~. ~ is possible becaus_e the em.tSS100 of ~hese
`lamps) and dimmers in interior illumination result in
`lamps 1s mainly concentrat~ m three comparauvely 30 colour temperatures down to about 2000 K. A disad-
`narrow spectral bands. For this purpose the lamps con-
`vantage of the aforementioned heavily loaded fluores-
`tain a red luminescing material whose emissio~ ~y cent lamps is that due to the intense blue mercury radia-
`lies in the range of 590-630 nm and a green lummescmg
`tion they cannot be used in the frequently desired col-
`material whose emission mainly lies in the range of
`our temperature range of about 2000 to about 2700 K.
`520-565 nm. The required emission in the third spectral 35 The invention has for its object to obviate the said
`range, i.e. the range of 430-490 nm, is supplied in many
`disadvantage and in general to provide means for shift•
`cases by a blue lumincscing material. However,. the
`ing the colour point of heavily loaded three-band fluo-
`visiblc radiation emitted by the mercury vapour dis-
`rescent lamps and for reducing the colour temperature,
`charge itself also provides a contribution (i.e. the ernis-
`while substantially maintaining the good general colour
`sion of the 436 nm mercury line) in this spectral range. 40 rendition and the high relative luminous flux.
`The lamps emit white light at a given colour tempera(cid:173)
`SUMMARY OF THE INVENTION
`ture, that is to say that the colour point (x.y in the C1E
`colour coordinate diagram) of the emitted radiation lies
`A low-pressure mercury vapour djscharge lamp of
`on or near the line of the black body radiators. The
`the kind described in the opening paragraph is charac-
`colour point of fluorescent lamps oflow colour temper- 45 terized according to the invention in that the lamp is
`ature is generally chosen to lie preferably slightly above
`provided with an absorption layer comprising an alumi-
`(for example about 0.010 in y coordinate) the line of the
`nate activated by trivalent cerium and having a garnet
`black body radiators.
`crystal structure.
`A desired colour temperature of the light emitted by
`The said garnet is a known luminescent material (See
`a three-band fluorescent lamp is obtained by a suitable so for example J.O.S.A., 59, No. 1, 60, 1969), which ab-
`adjustment of relative contnbutions in the three spectral
`sorbs short-wave ultraviolet radiation, but especially
`ranges to the overall emission of the lamp. As the colour
`absorbs radiation having a wavelength between about
`temperature of the lamp is lower, the contribution in the
`400 and 480 nm and converts it into radiation in a wide
`blue range of 430-490 nm should be smaller. It follows
`emission band (half-value width of about 110 nm) with
`from the aforementioned Netherlands Patent Specifica- ss a maximum at about 560 om. It has been found that the
`tion No. I 64,697 that the minimum attainable colour
`use of such a luminescent garnet in an absorption layer
`temperature for lamps having an inner diameter of the
`for three-band fluorescent lamps leads to a shift of the
`tubular discharge envelope of about 36 mm is about
`colour point of the radiation emitted by the lamp and
`2300 K., in which event the lamp need no longer con•
`allows for a reduction of the colour temperature of the
`tain a blue luminescing material and all the required 60 lamp.
`radiation in the blue spectral range originates from the
`A reduction of the colour temperature in itself could
`blue mercury radiation. In lamps having a smaller inner
`be attained with any yellow pigment absorbing blue
`diameter of the discharge envelope, especially a diame-
`radiation. However, a yellow pigment leads to a reduc-
`ter of about 24 mm, the mercury vapour discharge is
`tion (unacceptable for this lamp type) of the relative
`found to be more efficient the relative contribution of 65 luminous flux so that it cannot be used.
`the blue mercury line being larger. Consequently for
`The use of the luminescent garnet in lamps according
`these lamps, the minimum attainable colour temperature
`to the invention has the advantage that the absorbed
`is found to have a higher value, i.e. about 2500 K.
`radiation is no lost, but is converted with a high effi-
`
`LOW-PRESSURE MERCURY VAPOUR
`DISCHARGE LAMP
`
`.... -~
`
`(cid:47)(cid:50)(cid:58)(cid:40)(cid:54) 1029, Page 3
`VIZIO Ex. 1029 Page 0003
`
`

`

`4,727,283
`
`IS
`
`3
`ciency into visible radiation so that high relative lumi(cid:173)
`nous fluxes are obtained. In addition, the lamps accord(cid:173)
`ing to the invention have high values of R(a, 8), which
`could not be expected because it is known for three(cid:173)
`band fluorescent lamps that radiation in the range of 5
`565-590 nm, in which a comparatively large part of the
`emission of the garnet is found, is detrimental to the
`colour rendition properties.
`A preferred lamp according to the invention is char(cid:173)
`acterized in that the luminescent aluminate having a IO
`garnet structure corresponds to the formula Ln3.,.Ce,..
`Als-p-qGapSc,,012, in which Ln is at least one of the
`elements yttrium, gadolinium, lanthanum and lutetium
`and in which
`0.01::::§x::::§0.15
`0~p~3 and
`0~q~l.
`As appears from the formula and conditions, in the
`garnet one or more of the elements Y, Gd, La and Lu 20
`may be used as the cation Ln and the aluminium may be
`partly replaced within the aforementioned limits by
`gallium and/or scandium. The Ce activator replaces
`part of the Ln and is present in a concentration x of0.01
`to 0.15. Ce contents lower than 0.Ql lead to materials 25
`having an insufficient blue absorption, while for Ce
`contents higher than 0.15 the garnet is formed insuffi(cid:173)
`ciently and undesired subphases may be obtained.
`Preferably, such a lamp according to the invention is
`characterized in that in the garnet Ln is yttrium and in 30
`that the garnet does not contain Ga and Sc(p=q=0).
`Such materials in fact have the most favourable absorp•
`tion properties and supply the highest luminous fluxes.
`In an embodiment of a lamp according to the inven(cid:173)
`tion, the absorption layer is disposed on the outer sur- 35
`face of the discharge envelope. This bas the advantage
`that the mercury resonance radiation produced in the
`lamp is utilized to the optimum and the absorption layer
`only absorbs the undesired blue radiation and converts
`it into visible radiation. In general, such a lamp will be 40
`provided with protection, for example an outer bulb, or
`will be used in a closed luminaire.
`Another embodiment of a lamp according to the
`invention is characterized in that the absorption layer is
`disposed on the inner surface of the discharge envelope 45
`and in that the luminescent layer is disposed on the side
`of the absorption layer facing the discharge. In this
`lamp, the mercury resonance radiation will mainly be
`absorbed by the luminescent layer. The use of an outer
`bulb or a closed luminaire is not necessary for this lamp. so
`Another embodiment of a lamp according to the
`invention is characterized in that the garnet activated
`by trivalent cerium is mixed with the luminescent mate•
`rials ~f the luminesc~t layer so that the luminescent 55
`layer is at the same tune the absorption layer. Such a
`lamp can in fact be manufactured in a simple manner
`because the absorption layer and the luminescent layer
`can be introduced into the lamp in a single operation.
`In a particularly advantageous embodiment a lamp 60
`according to the invention comprises a discharge enve(cid:173)
`lope, a ballast unit and an ignition unit, and optional
`reflectors, all in a common envelope consisting of a
`bottom portion comprising a cap and an outer bulb
`transparent to radiation, and is characterized in that an 65
`absorption layer is disposed on at least parts of the sur(cid:173)
`face of the ballast unit and/ or ignition unit and/ or of the
`bottom portion and/or the reflectors.
`
`4
`BRIEF DESCRIPTION OF THE DRAWINGS
`Embodiments of lamps according to the invention
`will now be described more fully with reference to the
`drawing in which:
`FIG. 1 shows in elevation and partly broken away a
`low-pressure mercury vapour discharge lamp compris(cid:173)
`ing two parallel tube portions interconnected by a cou(cid:173)
`pling tube, and
`FIG. 2 shows diagrammatically a low-pressure mer(cid:173)
`cury vapour discharge lamp capped on one end, which
`is suitable to replace incandescent lamps.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`The lamp shown in FIG. 1 comprises a glass dis(cid:173)
`charge envelope 1 sealed in a gas-tig:ht manner and
`comprising two parallel tube portions 2 and 3 intercon(cid:173)
`nected by a coupling tube 4. The discharge envelope 1
`contains a small quantity of mercury and argon at a
`pressure of 400 Pa and is further provided at its inner
`surface with a luminescent layer S. The layer S com(cid:173)
`prises a red luminescing yttrium oxide activated by
`trivalent europium and a green luminescing terbium(cid:173)
`activated cerium magnesium aluminate. An electrode
`(not shown in the drawing) is arranged at each of the
`ends of the tube portions 2 and 3 remote from the cou(cid:173)
`pling tube 4 and these electrodes constitute the means
`for maintaining a column discharge in the gas filling.
`The ends of the tube portions 2 and 3 located near the
`electrodes are connected to a lamp base 6, which carries
`two current-supply pins 7 and 8 and in which a glow
`starter (not shown) is arranged. The discharge envelope
`1 is coated throughout its outer surface with a thin
`absorption layer 9 of yttrium aluminate activated by
`trivalent cerium having a garnet structure. The inner
`diameter of the tube portions 2 and 3 is 10 mm and the
`length of the U-shaped discharge path is about 200 mm.
`During operation, the lamp comsumes a power of 9 W
`and the load of the luminescent layer S, i.e. the power
`consumed by the column divided by the surface area of
`the luminescent layer S, is about 1350 W / m2.
`The lamp of FIG. 2 has an envelope 1 comprising a
`glass outer bulb 2 and a bottom portion 3, which is
`connected to the bulb and is provided with a cap in the
`form of an E 27 lamp base 4. In the envelope 1 are
`arranged a discharge bulb S, a ballast unit 6 and an
`ignition unit (not shown in the drawing) provided in the
`bottom portion 3. The discharge bulb S comprises a
`glass tube having an inner diameter of 9. 5 mm, this tube
`being bent into the shape of a hook comprising four
`adjacent parallel extending tube portions intercon(cid:173)
`nected by three curved tube portions. The discharge
`bulb S contains a small quantity of mercury and an
`amalgam and a tnixture of argon and neon at a pressure
`of300 Pa. Electrodes 7 and 8, respectively, are arranged
`at the ends of the bulb S and the inner surface of the bulb
`S is provided with a luminescent layer 9 comprising red
`and green luminescing materials of the type mentioned
`in FIG. 1. The bulb S is arranged with its free ends in a
`bottom plate 10, which is secured in the bottom portion
`3. The bottom plate 10 and the ballast unit 6 are coated
`with thin absorption layers 11 and 12, respectively, of
`cerium-activated yttrium aluminate. The lamp con(cid:173)
`sumes during operation a power of 18 W. The length of
`the curved discharge path is about 390 mm and the
`power consumed by the column divided by the surface
`
`(cid:47)(cid:50)(cid:58)(cid:40)(cid:54) 1029, Page 4
`VIZIO Ex. 1029 Page 0004
`
`

`

`5
`area of the luminescent layer 9 has a value of 1250
`W/m2.
`
`4,727,283
`
`ex.
`a s
`6
`7
`
`A (mg)
`0
`2S
`so
`75
`
`0.457
`0.466
`0.475
`0.480
`
`6
`TABLE II
`R (a.8) L0 (Im)
`y
`0.411
`564
`82
`0.423
`81
`573
`0.436
`81
`S66
`0.444
`80
`566
`
`Lrnoo(lml
`502
`502
`sos
`513
`
`EXAMPLES I TO 4
`Four lamps (designated 1 through 4) of the type de- S
`scribed with reference to FIG. 1 (9 W) were provided
`with a thin uniform absorption layer of cerium-
`activated garnet according to the formula Y2.9Ceo.tAl-
`It is again seen that the absorption layer leads to a shift
`of the colour point by about 6.y= 1.5~x. The lamps s, 6,
`50 12, which layer was disposed on the outer surface of
`the discharge bulb. For each lamp a different layer 10 and 7 all had a luminescent layer with the same ratio of
`the quantity of red luminescing material to that of the
`thickness was used. In the following Table I, the overall
`mass of the garnet used in the absorption layer (A in
`green luminescing material as the lamp a, which has a
`mg), the colour point (x,y) of the light emitted by the
`colour temperature of about 2750 K. A small enlarge-
`lamp and the luminous flux obtained (L in lumen) are
`indicated for each of these lamps. For comparison, (x, 15 ment of this ratio yields for the lamp Sa colour point
`near the line of the black body radiators, in which event
`y) and L were measured on a lamp designated a) with•
`the colour temperature is about 2500 K. In a corre-
`out an absorption layer, but otherwise identical to the
`Jamps 1-4. These value also indicated.
`sponding manner, even lower colour temperatures
`(down to about 2000 K.) can be attained for the lamps 6
`____ _ __ T_A_B_L_E_I ____ __ _
`and 7.
`20
`•
`example
`A (mg)
`L(lm)
`0
`564
`0.451
`0.468
`59
`5S8
`n
`0.470
`542
`0.473
`542
`80
`0.483
`536
`!SO
`
`a
`i
`2
`3
`4
`
`y
`0.411
`0.429
`0.434
`0.439
`0.450
`
`25
`
`EXAMPLE 8
`A lamp (8) of the kind described with reference to
`FIG. 2 (18 W) was provided with a Y2.9Ceo.1 AlsO12-
`containing absorption layer disposed on the bottom
`plate on the ballast unit and on the side of the upright
`edge of the bottom portion facing the discharge bulb.
`The lamp had a colour point of the emitted radiation
`x=0.46S and y=0.417, which is very close to the de(cid:173)
`sired point (x=0.468 and y=0.418). An identical lamp,
`but without an absorption layer, had a colour point
`x=0.461 and y=0.412.
`
`It clearly appears that with increasing thickness of the
`absorption layer an increasing shift of the colour point
`occurs, where total 6.y= 1.56.x. The colour temperature
`3
`of the light emitted by the lamp a is about 2750 K and O
`the colour point lies substantially on the line of the black
`body radiators.
`· If now in the luminescent layer of the lamps 1-4 the
`ratio ?f the quantity of r~ luIIl!nescing ~at~rial to the
`·quantity of the green IW11111esc1t1g matenal 1s enlarged
`(this ratio must be larger as the absorption layer is
`thicker) so that the colour point of the lamp shifts to an
`area on or near the line of the black body radiators, a
`colour temperature is attained of about 2400, 2340, 2200
`~d 2000 K for the lamps 1-4, respectively.
`EXAMPLES S TO 7
`Three lamps (5, 6 and 7) of the kind shown in FIG. 1
`(9 W), but without an outer absorption layer, were
`coated on the inner side of the discharge bulb with 45
`varying thicknesses of an absorption layer of cerium(cid:173)
`activated garnet according to the formula Y2.9Ceo.1Al•
`
`35
`
`EXAMPLES 9 TO 11
`Three lamps (9, 10 and 11) of the kind described with
`reference to FIG. 2 (18 W) were provided with a lumi(cid:173)
`nescent layer consisting of a mixture of green luminesc(cid:173)
`ing terbium-activated cerium magnesium aluminate
`(CAT), red luminescing yttrium oxide activated by
`trivalent europium (YOX) and cerium-activated garnet
`~
`(YAG) according to the formula Y2_9Ceo.1Al5O12. In
`these lamps, the luminescent layer therefore also ful(cid:173)
`filled the function of absorption layer. In the following
`Table III, the composition of the luminescent layer (in
`% by weight) of the colour point (:x, y), the colour
`temperature {Tc in K.), luminous efficacy (1J in I m/W)
`and the general colour rendition index R (a, 8) are indi(cid:173)
`cated for these lamps.
`
`TABLE III
`CAT
`YAG
`YOX
`example % by weight % by weight % by weight
`9
`10
`II
`
`30.8
`26.8
`23.0
`
`66.5
`67.9
`68.J
`
`2.1
`S.3
`8.9
`
`Tc
`(K)
`y
`0.477 0.414 2500
`0.493 0.415 2325
`0.508 0.415 2175
`
`T)
`(lm/W) R (a.8)
`49.0
`48.4
`47.6
`
`80
`82
`83
`
`Finally, it should be noted that the luminescent layer
`of a lamp according to the invention may comprise
`sO12. On this absorption layer, a luminescent layer con-
`sisting of a mixture of red luminescing Y2O3-Eu3+ and 60 besides a red luminescing and a green luminescing mate-
`green luminescing CeMgA111O19-Tb is provided. In the
`rial also a small quantity of a blue luminescing material,
`following Table II, for each lamp the mass of the ab-
`as is also the case in three-band fluoresc.ent lamps hav-
`ing a high colour temperature. In the present heavily
`sorption layer (A in mg), the colour point (x, y), the
`general colour rendering index R (a, 8), the luminous
`loaded lamps, this can afford advantages because the
`flux at O hours (Lo in I m) and the luminous flux after 65 blue luminescing material provides an additional degree
`1000 operating hours (L1000 in I m) are indicated. For
`of freedom for reaching a desired value of the colour
`point of the lamp.
`comparison, these values are also indicated for the lamp
`What is claimed is:
`a without an absorption layer.
`
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`

`7
`1. A low-pressure mercury vapour discharge lamp,
`whose emission mainly lies in three spectral ranges and
`whose colour temperature of emission lies in the range
`of 2000-3000 K., the lamp comprising a gas-tight dis(cid:173)
`charge envelope transparent to radiation and having a S
`gas filling comprising mercury and a rare gas, a lumines(cid:173)
`cent layer comprising luminescent materials whose
`emission mainly lies in the ranges of 590-630 nm and
`520-565 nm, means for maintaining a column discharge
`in the gas filling, the power consumed by the column 10
`being at least 500 W per m2 surface area of the lumines(cid:173)
`cent layer,
`characterized in that the lamp is provided with an
`absorption layer comprising a luminescent alumi(cid:173)
`nate activated by trivalent cerium and having a 15
`garnet crystal structure.
`2. A lamp as claimed in claim 1, characterized in that
`the luminescent aluminate having a garnet structure
`corresponds to the formula Ln3._.Ce_.Als-p-qGapScqO12,
`in which Lo is at least one of the elements yttrium, 20
`gadolinium, lanthanum and lutetium and in which
`0.0l~x~0.15
`o:ap:aJ
`0~q~l.
`3. A lamp as claimed in claim 2, characterized in that 25
`Ln is yttrium and p=q=0.
`4. A lamp as claimed in claim 3, characterized in that
`the absorption layer is disposed on the outer surface of
`the discharge envelope.
`5. A lamp as claimed in claim 3, characterized in that 30
`the absorption layer is disposed on the inner surface of
`the discharge envelope and in that the luminescent layer
`is disposed on the side of the absorption layer facing the
`discharge.
`6. A lamp as claimed in claim 3, characterized in that 3S
`the garnet activated by trivalent cerium is mixed with
`the luminescent materials of the luminescent layer
`whereby the luminescent layer also is the absorption
`layer.
`7. A lamp as claimed in claim 3, including a ballast 40
`unit and an ignition unit, which are arranged together
`with the discharge envelope in a common envelope
`consisting of a bottom portion comprising a cap and of
`an outer bulb transparent to radiation, characterized in
`that the absorption layer is disposed on at least parts of 45
`the surface of one or more of the ballast unit, the igni(cid:173)
`tion unit and the bottom portion.
`8. A lamp as claimed in claim 2, characterized in that
`the absorption layer is disposed on the outer surface of
`the discharge envelope.
`
`so
`
`4,727,283
`
`8
`9. A lamp as claimed in claim 1, characterized in that
`the absorption layer is disposed on the outer surface of
`the discharge envelope.
`10. A lamp as claimed in claim 2, characterized in that
`the absorption layer is disposed on the inner surface of
`the discharge envelope and in that the luminescent layer
`is disposed on the side of the absorption layer facing the
`discharge.
`11. A lamp as claimed in claim 1, characterized in that
`the absorption layer is disposed on the inner surface of
`the discharge envelope and in that the luminescent layer
`is disposed on the side of the absorption layer facing the
`discharge.
`12. A lamp as claimed in claim 2, characterized in that
`the garnet activated by trivalent cerium is mixed with
`the luminescent materials of the luminescent layer and
`in that the luminescent layer also is the absorption layer.
`13. A lamp as claimed in claim 1, characterized in that
`the garnet activated by trivalent cerium is mixed with
`the luminescent materials of the luminescent layer and
`in that the luminescent layer also is the absorption layer.
`14. A lamp as claimed in claim 2, including a ballast
`unit and an ignition unit, which are arranged together
`with the discharge envelope in a common envelope
`consisting of a bottom portion comprising a cap and of
`an outer bulb transparent to radiation, characterized in
`that the absorption layer is disposed on at least parts of
`the surface of one or more of the ballast unit, the igni(cid:173)
`tion unit and the bottom portion.
`15. A lamp as claimed in claim 1, including a ballast
`unit and an ignition unit, which are arranged together
`with the discharge envelope in a common envelope
`consisting of a bottom portion comprising a cap and of
`an outer bulb transparent to radiation, characterized in
`that the absorption layer is disposed on at least parts of
`the surface of one or more of the ballast unit, the igni(cid:173)
`tion unit and the bottom portion.
`16. A lamp as claimed in claim 7, including at least
`one reflector arranged within the envelope, character(cid:173)
`ized in that the adsorption layer is disposed on at least a
`portion of the surface of the reflector.
`17. A lamp as claimed in claim 14, including at least
`one reflector arranged within the envelope, character(cid:173)
`ized in that the absorption layer is disposed on at least a
`portion of the surface of the reflector.
`18. A lamp as claimed in claim 15, including at least
`one reflector arranged within the envelope, character(cid:173)
`ized in that the absorption layer is disposed on at least a
`portion of the surface of the reflector.
`• • • • •
`
`ss
`
`60
`
`6S
`
`(cid:47)(cid:50)(cid:58)(cid:40)(cid:54) 1029, Page 6
`VIZIO Ex. 1029 Page 0006
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