HIGH INTENSITY DISCHARGE LAMP FOR VEHICLES

LAMPE A DECHARGE A HAUTE INTENSITE POUR FEUX DE VEHICULES

English Abstract

The present invention provides a high intensity discharge lamp with a lamp
cap,
which has a simple and firm structure, higher thermal stability, lower glare
and higher
efficiency than conventional lamps. The discharge lamp according to the
present
invention comprises an arcuate inner tube, which is filled with substances,
e.g. xenon, for
gas discharge. The arcuate inner tube comprises a bulbous or ellipsoidal
portion.
Surrounding the arcuate inner tube is a tubular outer envelope; the outer
envelope has an
enlarged portion, which is similar to the bulbous or ellipsoidal portion
disposed of the
bulbous portion of the arcuate inner tube. The distance between the outer
envelope and
the outer wall of the arcuate inner tube is uniform; thereby making the
temperature
distribution on the wall of inner tube more uniform, which improves the
thermal stability,
and the luminous and the electricity parameters of the lamp. More important is
that the
invention can reduce the light refraction and reflection, which occurs between
the inner
surface of the outer envelope and the outer surface of the arcuate inner tube,
and also
between the two interfaces of the outer envelope wall and the space
therebetween,
thereby more light is directly emitted out from the enlarged bulbous portion
of the lamp,
and the occurrence of glare is reduced.

French Abstract

L'invention concerne une lampe à décharge haute résistance pourvue d'un couvercle de lampe et présentant une structure simple et solide, une haute stabilité thermique, un faible éblouissement et un rendement élevé. Cette lampe à décharge comprend un tube à arc rempli de substances ionisées. Le tube à arc comprend une partie bulbeuse ou ellipsoïdale. Une enveloppe tubulaire entoure le tube à arc, cette enveloppe comportant une partie élargie similaire à la partie bulbeuse ou ellipsoïdale, ladite partie élargie étant disposée autour de la partie bulbeuse du tube à arc. La distance entre l'enveloppe et la paroi extérieure du tube à arc est constante, ce qui permet d'obtenir une température de tube à arc plus régulière et d'améliorer la stabilité thermique et les paramètres photoélectriques de la lampe. L'invention permet de réduire le temps de réflexion entre la paroi intérieure de l'enveloppe et la paroi extérieure du tube à arc. Ainsi, une quantité plus importante de lumière est directement émise à l'extérieur de l'enveloppe. Cette invention permet en outre de réduire l'éblouissement aveuglant.

Claims

We claim
1. A discharge lamp for vehicles comprising:
a cylindrical inner tube including an arcuate section;
a gastight outer envelope including a bulbous-shaped section surrounding the
arcuate section and substantially parallel thereto;
a cap for supporting the outer envelope;
an annular hoop, including a plurality of wings with holes therethrough,
surrounding a lower end of the outer envelope; and
a plurality of poles extending from the cap inserted into said plurality of
holes,
respectively;
wherein, in the space between the inner tube and the outer envelope, air is
exhausted at a pressure below atmospheric.
2. The lamp as claimed in claim 1, wherein the bulbous-shaped section of the
outer
envelope is elliptical or cylindrical with a diameter larger than other
sections of the
envelope.
3. The lamp as claimed in claim 1 or 2, wherein an end of the inner tube is
enlarged
forming a conical recess; and wherein an outer edge of the end of the inner
tube is fixed
to an end of the outer envelope.
4. The lamp as claimed in claim 1, 2 or 3, wherein the annular hoop comprises
one,
two or four pieces of metal ribbons.
5. The lamp as claimed in any one of claims 1 to 4, wherein the inner tube
comprises
quartz glass, and the outer envelope comprises UV stop quartz glass.
6. The lamp as claimed in any one of claims 1 to 5, wherein the inner tube is
filled
with xenon and a suitable amount of Hg and metal halide pellet.
6

7. The lamp as claimed in claim 6, wherein the inner tube is pressurized to at
least
six atmospheres.
8. The lamp as claimed in any one of claims 1 to 7, wherein a distance between
the
outer envelope and an outer wall of the inner tube is uniform, thereby making
a
temperature distribution on the inner tube more uniform.
9. A capped xenon metal halide discharge lamp for vehicles comprising:
a cylindrical inner tube having walls made of pure quartz glass and filled
with
high pressure xenon;
a gas tight outer envelope having walls, with said outer envelope disposed
surrounding said inner tube, a portion of said outer envelope disposed
proximate to said
inner tube, and wherein said walls of said inner tube and said walls of said
outer envelope
are generally parallel;
a mercury and metal halide pellet disposed in said inner tube, wherein said
outer
envelope is made of glass, which prevents transmission of ultra violet light,
wherein said
inner tube and said outer envelope define a space therebetween, wherein said
space is
exhausted to form a vacuum;
a cap for supporting the outer envelope;
a plurality of poles formed on said cap; and
a hoop having a plurality of holes and said holes matching said plurality of
poles
formed on said cap.
10. The capped xenon metal halide discharge lamp for vehicles as claimed in
claim 9,
wherein said hoop comprises two portions.
11. The capped xenon metal halide discharge lamp for vehicles as claimed in
claim 9,
wherein said hoop comprises four portions.
12. The capped xenon metal halide discharge lamp for vehicles as claimed in
claim 9,
wherein said cap comprises a recess with said inner tube projecting into said
recess.
7

Description

CA 02534009 2006-O1-26
Doc. No. 119-7 CA Patent
HIGH INTENSITY DISCHARGE LAMP FOR VEHICLES
Field of the Invention
The present invention relates to a vehicle lamp, and in particular to a low-
glare,
highly-efficient, high-intensity, discharge vehicle lamp.
Background of the invention
Conventional low power xenon metal halide discharge lamps, such as the capped
lamps disclosed in U.S. Patents Nos. 5,736,811 and 5,646,471, have been widely
used in
vehicle h eadlights i n Japan a nd E urope. U nfortunately, w hen t hese k
finds o f 1 amps a re
installed in vehicle lights, they always emit much more glare compared to
halogen
tungsten lamps. Therefore, engineers must design special reflectors, lenses,
lens hoods or
light s Melds t o 1 unit t he g Tare a nd form t he b eam p rofile t o m eet t
he r equirements o f
vehicle lamp regulations, which is very hard work and makes the manufacturing
costs
much higher.
The present invention transforms the glare into beam light and increases the
efficiency of the lamp.
The conventional capped xenon metal halide vehicle lamps need a very complex
and
expensive accessory to fix the raw lamp stably in the right position on the
cap. The
present i nvention p rovides a m uch s impler w ay to f ix t he r aw 1 amp o
nto t he c ap a t a
much lower cost.
2()
It is an object of the present invention to provide a capped xenon metal-
halide
vehicle lamp with high light beam efficiency, less glare, more unifornl wall
temperature
distribution, more stable luminous and electricity parameters, and at lower
cost.
Brief description of the drawings
Embodiments of invention xenon metal halide lamp for vehicles are shown in the
drawing, in which
Fig.l illustrates a partially sectioned side view of the vehicle lamp in
accordance the
present mventron;
Fig.2 illustrates reflection light, refraction light and transmission light
from a glass
plate;

CA 02534009 2006-O1-26
Doc. No. 119-7 CA Patent
Fig.3 illustrates the beam light trace from the ball shaped envelope of the
lamp of the
presentmvent~on;
Fig.4 shows the beam light trace from a tubular envelope of a conventional
lamp;
Fig.S is a top view of a cap with a ring shaped hoop for fixing the lamp;
Fig. 6 is an isometric view of the cap of Fig 5;
Fig.7 illustrates a the ring shaped hoop with four wing holes formed by one
metal
ribbon;
Fig.8 illustrates a half of the ring shaped hoop;
Fig.9 illustrates the half ring shaped hoop constructed by two sections; and
I O Fig.l 0 is an isometric view of the cap of a lamp with four implanted
poles.
Description of the invention
A capped vehicle discharge lamp, according to the present invention includes a
generally c ylindrical inner tube 1 with an a rcuate, e.g. spherical or
ellipsoidal, tubular
1 ~ portion 1 a and two cylindrical neck shaped portions 2a and 2b, which are
sealed gastight
with two electrode connectors 3a and 3b extending therethrough. Preferably,
the inner
tube 1 is filled with high-pressure xenon, pressurized to at least six
atmospheres, with a
suitable amount of Hg and metal halide pellet. The arcuate tubular portion 1 a
and the two
neck-shaped cylindrical portions 2a and 2b are surrounded by an outer gastight
tubular
20 envelope 5 with a bulbous, e.g. spherical or ellipsoidal, portion Sa
surrounding the
arcuate tubular portion I a and substantially parallel thereto. Preferably,
the inner tube 1
is comprised of quartz glass, and the outer envelope 5 is comprised of UV stop
quartz
glass.
A first end of the tubular envelope 5 is fixed on a cap 15. A first conductive
wire 6
25 extends from a first current supply conductor 13, which extends from the
bottom of cap
I S into an annular base I Sa, through the cap I S for directly connecting to
a first current
supply conductor 4a. A conductive wire 7, e.g. made of nickel, extends through
a bridge 8
or is directly connected to a second current supply conductor 4b of the second
electrode
3b. The conductive wire 7 runs along the outside of the lamp in a protective
sleeve 9 to
30 connect to a second current supply conductor 14. An inverted bell-shaped
end 2c of the
second neck shaped portion 2b of the inner tube I is expanded, whereby during
2

CA 02534009 2006-O1-26
Doc. No. 119-7 CA Patent
manufacture, the edge of the end 2c nearly touches the upper edge of the outer
envelope 5
enabling the two edges to be sealed gastight by suitable heating methods, e.g.
by flame.
With reference to Figures 5 to I 0, an opening 1 G at the center of an upper
surface of
the cap 15 forms a cylindrical shaped recess 17. A plurality of, e.g. three or
more,
stainless steel poles I 1 implanted in the cap's upper surface surround the
recess 17. A first
end of the lamp, e.g. a lower end of the outer envelope 5, is inserted in the
recess 17, and
an annular hoop 10, constructed by one, two or four sections, is tightly bound
around the
lower part of outer envelope 5. The four poles 11 are inserted in four holes
l0a and l Ob
on the wings of ring shaped hoop 10, respectively, and melted together by spot
welding.
The outer envelope 5 of the lamp is not perfectly tubular shaped, but includes
a
bulbous-shaped portion Sa surrounding the arcuate tubular portion 1 a of the
inner tube 1,
in contrast to the inner tube of a conventional xenon metal halide vehicle
lamp, which is
surrounded by a straight tubular envelope. The present invention is very
helpful in
reducing the glare from the inner tube and in increasing the lighting
efficiency, which will
become very clear from the following description.
According to optics theory, when a light beam is projected at a glass plate
with
incident angle i (Fig.2), a part of the light beam will be reflected at the
interface I,
between the air and the glass plate, with reflection angle I, which is the
same as incident
angle, and another part of the light beam, which passes into the glass plate
will be
refracted by the glass with an angle of refraction i'.
.,
n~sin i=n,sin t
Where n, and n~ are the refractive index of air and glass, respectively.
The refracted light beam will be divided to two parts at a second interface II
of glass
and air, the first part will go out through the glass plate and become
transmission light,
while another pan of the refracted beam will be reflected again by the second
interface 1I,
then go back to first interface I. A part of the reflected light will pass
through the first
interface I and become reflection light, while another part of it will be
reflected again by
ftrst interface I. Obviously, a part of the reflected light will continue to
reflect between
the two interface I and II time after time, and every time a part of the
reflected beam light
will pass through the second interface II and become transmission light.
3

CA 02534009 2006-O1-26
Doc. No. 119-7 CA Patent
From the simple geometric optic theory of reflection, refraction and
transmission,
we understand that, for xenon metal halide lamps with a tubular outer envelop,
the light
emitted from the inner tube 1 will be reflected partially by the inside
surface I of the outer
envelope 5 (Fig.4) and another part of the light, which passes through the
interface 1, will
enter the glass outer envelope 5 and will be refracted by the envelope's glass
material,
and then partially transmitted and partially reflected, as the light beam
arrives at the outer
interface II of the envelope 5 and the air. This process will continue in the
space between
interfaces I and II, in the space between the inner tube 1 and the envelope 5,
and also
between the outer surface and the inside surface of the inner tube 1.
Therefore, the light
emitted from the inner tube 1 is separated, a part of which is directly
emitted out as a
transmission beam, while another part diverges toward the two ends and decays
along the
lamp axis (see Fig.4) because of inten~al reflections and refraetions.
All o f t he d iverging 1 fight i s t he s ource o f glare, w hick i s t he r
eason w by d rivers
always think that serious glare results from xenon metal halide lamps.
The main features of this invention are:
1. The outer envelope 5 of the lamp is tubular shaped, but with a bulbous
shaped section
Sa in the middle thereof, surrounding the arcuate shaped portion 1 a of the
inner tube
1. The wall of the bulbous shaped section Sa of the envelope 5 is
substantially parallel
with the wall of the arcuate portion 1 a of the inner tube 1; therefore the
light from the
inner tube 1 will be directly emitted out through the arcuate portion hand the
bulbous
shaped section Sa of the envelope 5 with very little reflection, because the
direction of
radiation is almost perpendicular to both of the two walls thereof (Fig.3)
Obviously,
compared with a straight tubular shaped envelope, the beam efficiency of the
lamp of
the present invention increases, while the glare is reduced. Furthermore,
since a
distance between the outer envelope 5 and an outer wall of the inner tube 1 is
uniform, e.g. the walls of the outer envelope 5 are parallel to the walls of
the inner
tube 1, a temperature distribution on the inner tube 1 is more uniform.
Specifically,
the bulbous shaped portion Sa of the envelope 5 provides a more uniform
temperature
distribution on arcuate tubular portion la of the inner tube 1, therefore many
of the
parameters of this lamp are improved, such as higher luminous efficiency,
better
rendering index, higher reliability and longer lifetime.
4

CA 02534009 2006-O1-26
Doc. No. 1 19-7 CA Patent
2. The sealing of the outer free end, i.e. the far from the cap 15, of the
present invention
is different than a conventional lamp since the far end of the envelope of a
conventional lamp is heated by a flame to the temperature that the glass, e.g.
quartz,
melts and then shrank together with the neck portion of the tube to obtain a
gastight
seal. To form the lamp, according to the present invention, the far end 2c of
the inner
tube 1 is not shrunk, but enlarged to extend outwardly forming a conical
recess, e.g.
an inverted bell-shaped mouth, before sealing, whereby the diameter of the
bell-
shaped mouth edge is close to, but smaller than, the inner diameter of the
outer
envelope S. To form a gastight seal both edges are moved together and heated
by a
special burner until they are melted together. The air between the inner tube
1 and the
outer envelope 5 is evacuated with a vacuum at a pressure less than
atmospheric
pressure.
The aforementioned sealing method is simpler than conventional methods,
results in less glare emitted from the end 2c, which acts like a window for
the emitted
light, and shortens the length of the lamp, which is good for anti vibration.
3. The third main feature of this invention is the way the lamp is fixed on
the cap 15. In
this invention a plurality of, e.g. three or more, stainless steel poles l0a
and lOb are
implanted in the surface of the cap 15 around the lamp, which is mounted in
the
center recess 1 G on the cap's surface, and there is a metal ring shape hoop
10
constructed by one, two or four sections, as shown in Figs. 7, 8 and 9, which
bind
around the lower part of lamp. The four poles 11 on the cap 15 are inserted in
four
wing holes l0a and lOb of the hoop 10, respectively, and melted together by
point
welding, which is simpler, cheaper and stronger than conventional mountings.
5

Representative Drawing