U.S. patent application number 14/349416 was filed with the patent office on 2014-08-28 for radiation source and light guiding device.
The applicant listed for this patent is Ivoclar Vivadent AG. Invention is credited to Bruno Senn.
Application Number | 20140242538 14/349416 |
Document ID | / |
Family ID | 46924367 |
Filed Date | 2014-08-28 |
United States Patent
Application |
20140242538 |
Kind Code |
A1 |
Senn; Bruno |
August 28, 2014 |
RADIATION SOURCE AND LIGHT GUIDING DEVICE
Abstract
The invention relates to a radiation source, in particular a
light curing device, for the polymerization of dental materials,
comprising a light conductor and a light generation device which
has at least two light sources, preferably semiconductor light
sources, in particular light diodes, and the radiation of which is
bundled by a reflector and fed into the light conductor. The light
sources differ from one another with respect to their light color
and/or their emission spectrum and are controllable separately for
changing the light color and/or the emission spectrum and/or the
spectral radiant power of the radiation emitted. The light
conductor has at least one monocore section and one multicore
section wherein the radiation emitted by the light sources is fed
into a monocore section of the light conductor. Further, the
invention relates to a light-conducting device for a radiation
source or a light curing device of this kind.
Inventors: |
Senn; Bruno; (Buchs,
CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ivoclar Vivadent AG |
Schaan |
|
LI |
|
|
Family ID: |
46924367 |
Appl. No.: |
14/349416 |
Filed: |
October 8, 2012 |
PCT Filed: |
October 8, 2012 |
PCT NO: |
PCT/EP2012/069832 |
371 Date: |
April 3, 2014 |
Current U.S.
Class: |
433/29 |
Current CPC
Class: |
G02B 6/02042 20130101;
G02B 6/421 20130101; G02B 6/4298 20130101; A61C 19/004 20130101;
G02B 6/04 20130101 |
Class at
Publication: |
433/29 |
International
Class: |
A61C 13/15 20060101
A61C013/15 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 6, 2011 |
EP |
11184195.3 |
Oct 2, 2012 |
EP |
12187017.4 |
Claims
1. A radiation source for the polymerization of dental materials,
comprising a light generation device, and a light conductor, the
light generation device having at least two light sources, the
radiation of which is bundled by a reflector and fed into the light
conductor, wherein the light sources differ from one another with
respect to their light color and/or their emission spectrum, in
that the different light sources are controllable separately for
changing the light color and/or the emission spectrum and/or the
spectral radiant power of the radiation emitted, and wherein the
light conductor has a monocore section and a multicore section, the
monocore section being disposed closer to the light sources than
the multicore section, and wherein the radiation bundled by the
reflector is transmitted directly to the monocore section.
2. The radiation source according to claim 1, wherein the monocore
section comprises a length that corresponds to at least 1.5 times
the diameter of the monocore section.
3. The radiation source according to claim 1, wherein the monocore
section and/or optical fibers of the multicore section comprise a
core glass and a cladding glass.
4. The radiation source according to claim 1, wherein there is a
coating at the outer surface of the monocore and/or on the
multicore section, which coating prevents the exit of light from
the light conductor thereat and/or reflects light impinging
thereon.
5. The radiation source according claim 1, wherein both monocore
and multicore sections are connected with one another at a
transition with the aid of an adhesive cement and/or a
glass-bonding adhesive that comprises and/or comprise a refraction
index similar to glass.
6. The radiation source according to claim 5, wherein a sleeve is
disposed at an outer circumference of the monocore section.
7. The radiation source according to claim 6, wherein the sleeve at
least extends over the transition between the monocore section and
the multicore section, and wherein in that a subsection of the
multicore section adjacent to the monocore section is surrounded by
the sleeve.
8. The radiation source according to claim 1, wherein the diameter
of the light conductor amounts to 6 mm to 13 mm.
9. The radiation source according to claim 1, wherein the monocore
and/or the multicore section are formed in a conical manner, only
over a portion of the lengths thereof.
10. The radiation source according to claim 1, wherein a light
entry side end of the light conductor is located at the monocore
section and a light exit side end is located at the multicore
section.
11. The radiation source according to claim 1, wherein the
multicore section comprises a bending or a cranked section.
12. The radiation source according to claim 1, wherein a light exit
surface of the multicore section extends at an angle of 2.degree.
to 90.degree. relative to a light entry surface that runs
perpendicular to the longitudinal extension of the monocore
section.
13. The radiation source according to claim 1, wherein a light
entry side end of the monocore section comprises a connection
interface to the light sources of the light curing device with the
aid of which a polymerizable dental material can be cured.
14. The radiation source according to claim 13, wherein the
connection interface is formed by a bushing that can be connected
with the light curing device positively and that is fixedly
connected with the light entry side end of the monocore
section.
15. A light conductor device for a medical or dental-medical
radiation source, for a light curing device for the polymerization
of dental masses, comprising a bar-shaped monocore light mixing
element made of at least one transparent material, a multicore
light conductor, a connection interface that is connectable to a
housing of the light source or the light curing device, the light
mixing element being connected to the light conductor in a firmly
bonded and light-conducting manner, and wherein the light mixing
element and the light conductor are received in the connection
interface in a firmly bonded, hermetically sealed manner and
capable of compensating for expansion such that the light conductor
device is autoclaveable.
16. The light conductor device according to claim 15, wherein the
light mixing element is formed in a rotationally symmetric
manner.
17. The light conductor device according to claim 15, wherein the
light mixing element is formed cylindrically and comprises a planar
light entry and/or exit surface.
18. The light conductor device according to claim 15, wherein the
light entry and/or exit surface comprises a polished surface and/or
a surface coating or reflection-reducing coating and/or is
impingeable by an immersion means.
19. The light conductor device according to claim 15, wherein the
light mixing element comprises a light-conducting core, made of a
core glass, comprising a first refraction index and a
light-conducting cladding, made of a cladding glass, comprising a
second refraction index, the second refraction index being lower
than the first refraction index.
20. The light conductor device according to claim 15, wherein the
light mixing element comprises a reflection enhancing coating or a
reflective sleeve at a circumferential surface of the light mixing
element.
21. The light conductor device according to claim 15, wherein the
diameter of the light mixing element is between 2 mm and 20 mm, and
wherein the length of the light mixing element is greater than 0.5
times the diameter and smaller than 5 times the diameter of the
light mixing element.
22. The light conductor device according to claim 15, wherein the
light conductor device comprises a connection interface to which
the light conductor is connected, the connection interface being
connectable to the housing in a self-aligned manner relative to the
light generation device.
23. The light conductor device according to claim 17, wherein at
least one of the light entry and/or light exit surfaces of the
light mixing element is formed in a planar manner.
24. The light conductor device according to claim 15, wherein the
light conductor device is provided and configured for retrofitting
a lighting device or a light curing device.
25. The radiation source of claim 1, wherein it is a light curing
device and wherein the at least two light sources are semiconductor
light sources.
26. The radiation source of claim 25, wherein semiconductor light
sources comprise light diodes.
27. The light conductor device according to claim 15, wherein the
at least one transparent material comprises glass.
28. The light conductor device according to claim 15, wherein the
light conductor device is autoclaveable after it is disconnected
from the housing.
29. The light conductor device according to claim 19, wherein the
second refraction index is 0.05 to 0.2 units lower than the first
refraction index.
30. The light conductor device according to claim 21, wherein the
diameter of the light mixing element is between 6 mm and 15 mm, and
wherein the length of the light mixing element is greater than 0.8
times the diameter and smaller than twice the diameter of the light
mixing element.
31. The light conductor device according to claim 21, wherein the
diameter of the light mixing element is between 8 mm and 13 mm.
32. The light conductor device according to claim 22, wherein the
connection interface is made of a highly temperature resistant
plastic material and wherein the connection interface comprises a
non-positive connection and/or a firmly bonded connection.
33. The light conductor device according to claim 32, wherein the
highly temperature resistant plastic material comprises a sulfone,
etherketone or imid plastic material or plastic composite material.
Description
[0001] The invention relates to a radiation source, preferably for
medical or dental-medical use, in particular a light curing device
for the polymerization of dental materials, according to the
preamble of claim 1, as well as to a light conductor device for a
radiation source or a light curing device of this kind, according
to the preamble of claim 15.
[0002] The term light, as used in the description and the claims
herein, does not only stand for electromagnetic radiation in the
visible spectral range but also for electromagnetic radiation in
the UV and near infrared range. When it is subsequently referred to
the preferably deployed light diodes (or LEDs or LED chips), these
terms shall also include other illuminants and radiation sources,
in particular semiconductor radiation sources, emitting visible
light, UV and/or near infrared light which--for reasons of better
readability--shall not be listed throughout the text. Even when it
is sometimes only referred to light curing devices, it is to be
understood by somebody skilled in the art that the corresponding
statements also apply to other radiation sources in the same manner
and need to give reference to them, too.
[0003] Light curing devices of this kind have been known for a long
time.
[0004] One example of the implementation of a light conductor from
the 1970s can be taken from DE 23 52 670. Already at that time,
flexible light conductors consisting of a single fiber have been
considered to be well known. The document also proves the
implementation of light-conducting liquids and of a flexible
plastic hose for the supply of a light conductor to be known.
[0005] Light conductors that consist of a single fiber and that may
also be referred to as a light-conducting rod, are basically
comparatively stiff or rigid and are thus hard to bend. Light
conductors filled with a liquid, on the other hand, are unfavorable
especially in applications in the oral region as there is the
danger that the patient--inadvertently--bites on the light
conductor and in this manner causes a leak.
[0006] In the 1980s, but also up to now, one has typically moved on
to multiple fiber light conductors; DE 297 09 785 is mentioned as
an example hereof.
[0007] Multiple fiber light conductors that are also referred to as
multicore light conductors, have the advantage of offering a
substantially improved bending property. The dentist is thus able
to impart the desired shape to the light conductor on the end side
thereof in order to maintain the light emission or exit at the
desired, partially deep-seated position.
[0008] By the way, the same applies to the use of light conductors
for light sensors for dental cameras but also, for example, to the
use of light conductors in endoscopes that require narrow radii of
curvature as well.
[0009] It has already been known for a long time that with the aid
of optically additive mixtures of base colors such as red, yellow
and blue it is possible to generate white light. This fact is
exploited by arranging LEDs of corresponding coloring closely
adjacent to one another and by guiding the light emissions thereof
to the light conductor.
[0010] In fact, so-called white LEDs have become known recently.
These, however, are still comparatively expensive at present, and
due to the light mixture the exact shade of color can be better
adapted to the requirements. It is also possible to select a
certain emission spectrum.
[0011] If a single LED or a single LED chip is used as the light
source, light emission takes place primarily on the upper side of
the LED chip that typically has a size of approximately 1 mm.sup.2.
If a multicore light conductor that typically has a diameter of 6
to 13 mm, is installed in front of the LED chip, the main light
emission typically only impinges on the 6 or 7 inner fibers,
whereas only a very small portion of the outer optical fibers are
utilized.
[0012] In order to prevent such a situation, it has become known to
use a collecting lens at the light entry side end of the optical
fibers. On the other hand, the additional provision of a collecting
lens means two further optical boundary surfaces with the
respective reflections so that the degree of efficiency
decreases.
[0013] In both cases of application mentioned, one therefore gladly
resorts to monocore light conductors or light-conducting rods,
especially since the entire cross-sectional area of the light
conductor can be taken by the optically effective medium in case of
the monocore technology, in contrast to the yield losses arising
from the use of multicore light conductors.
[0014] State-of-the-art light sources for medical or dental-medical
use that have been typically used up to now, for instance, for the
polymerization of dental materials, were constructed and designed
for the emission of certain predefined emission spectra.
[0015] Contrary hereto, the invention is based on the object of
producing a radiation source preferably for dental or
dental-medical use, in particular a light curing device for the
polymerization of dental materials, according to the preamble of
claim 1, as well as a light conductor device, according to the
preamble of claim 15, that, on the one hand, can be produced easily
and cost-effectively and can be used universally, and, on the other
hand, can be handled more ergonomically especially with medical,
preferably dental applications, and whose light color and/or
emission spectrum and/or spectral radiant power of the emitted
radiation can be adapted to the purpose of use and case of
application without the light emission or easy handling suffering
any damage.
[0016] This object is inventively solved by claim 1 with respect to
the radiation source and the light curing device. With respect to
the light conductor device for a device of this kind the object is
solved by claim 15.
[0017] Advantageous further developments emerge from the
description and in particular from the subclaims. All the technical
features disclosed in the description and the subclaims can be
combined with each other freely according to the expertise of the
respective person skilled in the art and can be jointly implemented
technically in connection with the features of the independent
claims 1 and 15.
[0018] Surprisingly, especially by the interaction of the reflector
arrangement, which feds the radiation directly into the light
mixing element, and this light mixing element the invention
achieves a very high degree of light mixing--in connection with a
very simple and cost-effective design and without increasing the
space requirements or the overall length--, and thus by using light
sources, in particular LEDs, which differ with respect to their
light color and/or their emission spectrum and which can be
controlled separately from one another a corresponding device can
be provided whose light color and/or emission spectrum and/or
spectral radiant power of the emitted radiation can be adapted to
the purpose of use and case of application without the light
emission or easy handling suffering any damage.
[0019] According to the invention it is particularly favorable that
due to the combination of monocore and multicore light conductors,
the advantages of both of them can surprisingly be achieved without
the disadvantages to be expected. The bad light mixing present in
the case of multicore light conductors is completely avoided, as
well as the only partial light impingement that is focused on the
central optical fibers. It is not necessary to use a collecting
lens or any other costly light mixing device on the entry side;
rather it is possible to directly feed the light radiation emitted
by the one or more LED chips to the monocore light conductor. Due
to the comparatively large light entry surface, the light conductor
completely absorbs the light radiation and guides it forward.
[0020] The present invention makes possible to homogenize and mix
the light generated in a light generation device and to distribute
it across the entire cross-sectional area of the light conductor
such that at the exit of the light conductor an area can be
illuminated homogeneously with respect to brightness and spectral
distribution. In this way, it enables an effective, simple and
low-loss coupling of the emitted light, that is generated in
particular by several light diodes or other semiconductor radiation
sources, into the light conductor.
[0021] In a modified embodiment of the invention more than one
multicore section and/or more than one monocore section are
connected with one another. This is favorable for example if the
light conductor is very long and comprises positions along its
extension at which is must be bent heavily. At said positions
multicore and further monocore sections are formed then.
[0022] Whereas optical fibers typically offer a light yield that is
15% lower compared to monocore light conductors, it is inventively
provided to at least divide in half these yield losses. If only the
front, thus first third of the light conductor on the light exit
side is formed to be multicore and the rearward two thirds of the
light conductor are formed to be monocore, the yield losses are
reduced from 15 to 5%.
[0023] Further it is particularly favorable that according to the
invention it is prevented that an image of the LED chip is
displayed by optical fibers or multicore light conductors. In the
monocore light conductor section, a strong mixing is produced that
in this way provides for the homogenization of light.
[0024] Nevertheless, the desired emission spectra can be provided
with the realization of several
[0025] LED chips of different colors, and in fact without the need
of using an additional collecting lens and further costly
homogenization devices. This also particularly applies for the
three light conductor chips having different colors and being
typically arranged in a triangle which, for instance, have emission
maxima in the red, green an blue spectral areas and which can be
used to produce any desired light color by additive light
mixing.
[0026] In the same way, the inventive solution can be integrated
into any conventional device very cost-effectively and requiring
only minimal changes to the construction. Furthermore, a very
simple installation or exchange of light conductors in the medical
or dental practice or, for instance, in the dental laboratory is
possible. Moreover, the inventive solution is also very easy to
maintain in the service workshop.
[0027] Surprisingly, in connection with the inventive light mixing
device an unexpectedly high degree of homogenization with respect
to the intensity distribution and the spectral emission curves
across the entire exit surface of the optical fiber bundle can be
achieved, in spite of the simple design and the very short overall
length of the light mixing device, i.e. the very short light mixing
distance within the light mixing element--in particular in
connection with the state-of-the-art reflector arrangement in the
light generation device of the devices--as well as due to the
repeated phase transition and boundary surface interactions between
solid and air and again solid in the light path of the optical path
of a device of this kind, i.e. for instance light diode/air,
air/reflector, reflector/air, air/protective glass, protective
glass/air, air/light mixing element, light mixing element/air,
air/fiber bundle--also due to reflections at the boundary surface
and resulting delay differences of different ray bundles in the
optical path and their superposition. However, at the same time
only very low losses of light occur with respect to the entire
radiation energy produced by the light diodes until the exit end of
the optical fiber bundle.
[0028] A further advantage of the inventive solution is that the
use of expensive fiber bundles comprising a randomized arrangement
of the individual fibers will not be necessary anymore in the
future, and in this way considerable savings can be made in the
production of light conductor on the one hand, and, on the other
hand, mechanical problems such as twisting and squashing of the
fibers do not occur anymore due to the thermal expansion in use and
in autoclaving.
[0029] Furthermore, the inventive solution enables a very easy and
cost-effective provision of lighting devices or light curing
devices whose emitted work spectra can be synthesized by means of
additive light mixing of the spectra of light diodes comprising
different emission spectra by electronically controlling the
different light diodes respectively. It is especially surprising
that in connection with the specific construction of the inventive
solution using only the simplest optical means, a very high degree
of homogenization can be achieved with respect to the intensity of
light and emission spectra across the entire lighting cross section
and at the same time the efficiency of the transmission of light
can be improved and power dissipation can be reduced.
[0030] Advantageously, the inventive light mixing device can be
positioned ideally with respect to the light diodes or
semiconductor light sources. In doing so, the positioning
parameters can be selected such that the entry surface of the light
mixing element is located "out of focus" with respect to the
respective focal points of the light diodes or reflectors assigned
to the semiconductor radiation sources, and is, on the one hand,
illuminated most comprehensively by the bundles of entry beams and
that, on the other hand, the entry angle area of the incoming
radiation exploits as completely as possible the entry or
acceptance cone predefined by the numerical aperture of the light
entry end of the light mixing element.
[0031] As a further advantage of the inventive solution every
unnecessary additional bending in the optical path of the light
path is avoided. In particular, any curvatures within a (monocore)
light-conducting rod can be omitted which, as has been shown,
result in considerable additional light losses within the light
path and worsen the degree of efficiency considerably.
[0032] Surprisingly, a further advantage of the invention is that
one light mixing element of a small entire length which is in the
order of magnitude of the diameter of the light mixing element is
able to mix light from differently colored LED chips or
semiconductor radiation sources of the different emission spectra
thereof properly such that properly mixed light enters the
multicore section of the light conductor and no variations in color
can be detected across the light exit surface of the light
conductor.
[0033] In an inventively particularly favorable manner the
transition between the monocore and the multicore section of the
light conductor can be realized maintaining the index of
refraction. For this purpose, a glass-bonding adhesive or an
adhesive cement can be used whose index of refraction corresponds
to that of the optical material used for the light conductor.
[0034] According to a further advantageous embodiment it is
provided to stiffen or reinforce the light conductor with the aid
of a sleeve that especially preferably extends over the transition
between the monocore and the multicore section. The sleeve offers
the additional advantage of preventing a stiffness jump that
reduces the load carrying capacity of the light conductor against
shear stress due to a lateral attachment to the application
location. The forces introduced are at least partially transferred
by the multicore section to the more rigid monocore section.
Nevertheless, the bending property and flexibility of the front end
of the light conductor is given on a large scale, i.e. at said
location at which the bending property is essential in the
practical application.
[0035] The sleeve consists preferably of metal, in particular of
stainless steel, and comprises a wall thickness which amounts to
less than a fifth, in particular less than a fifteenth of the
diameter of the light conductor. Alternatively, the sleeve can
comprise a highly temperature-resistant plastic material, in
particular a sulfone, etherketone or imid plastic material or
plastic composite material--to which the light conductor is
connected, preferably non-positively and/or in a firmly bonded
manner. In this way, the required temperature resistance,
mechanical strength and dimensional stability of the connection
interface can be ensured on the one hand, and due to the elastic
properties of the corresponding plastic materials a receptivity for
thermal expansion movements and a limitation of thermal stresses
can be achieved, on the other hand. At the same time, a connection
interface of this kind made of such a plastic material enables the
targeted use of press fits and/or preloads between the connection
interface and the light mixing element on the one hand which in
this case can be connected to the connection interface preferably
non-positively and/or in a firmly bonded manner, and on the other
hand between the connection interface and the connection component
to which the connection interface can be attached free of play and
securely with respect to changes in temperature using a press fit
and/or preloads.
[0036] Especially preferably a further transition occurs directly
from the monocore section to the multicore section, i.e. without an
air layer, and the index of refraction changes over the course of
the transition by less than 50%, in particular by less than
20%.
[0037] Compared to the flexible monocore light conductor known from
the publication DE-OS 23 52 670, the multicore section further has
the advantage that the yield losses decrease in relation to the
straight layout of the light conductor. A heavily bent multicore
light conductor typically offers lower attenuation than a monocore
light conductor curved in the same radius so that according to the
invention for the straight portion of the light conductor said
light conductor type (Monocore) having the smallest losses thereat
is combined with the light conductor type (Multicore) having the
smallest losses for the curved area.
[0038] It is particularly favorable if the multicore section
comprises a bending or a cranked section, in particular adjacent to
the light exit side end. Such a design and arrangement considerably
improves and facilitates the handling in use. Here, the light
losses are kept small.
[0039] In a further particularly favorable embodiment of the
invention it is provided that the monocore section comprises a
length that at least corresponds to 5 times its diameter. It is to
be understood that the length, however, is variable in both
sections, for example comprises a length two times, three times, up
to seven or even ten times the diameter.
[0040] The monocore and/or the multicore sections are conveniently
formed in a conical manner, at least over a part of the lengths
thereof, and in particular taper towards the end on the light exit
side end. Hereby, the light conductor can be configured to be
slimmer, thus improving the handling, for instance, in the mouth of
a patient and/or the radiation energy, for instance, from a larger
array of diodes can be concentrated on, for instance, a smaller
handling surface.
[0041] In an inventively favorable manner, both the monocore
section and the individual fibers of the multicore section consist
of a core glass and a cladding glass. In a manner known per se,
core glass and cladding glass strongly differ in their indices of
refraction which leads to the desired total internal reflection.
Such a coaxial design of the light mixing element made of two
different transparent materials, preferably of two types of glass,
comprising different indices of refraction can reduce radiation
losses in connection with total internal reflection and achieve a
better guidance of the radiation. Contrary to conventional light
conductors, just like those widely used in the field of light
waveguide technology, in the light mixing element mentioned here
there is preferably a large difference between both indices of
refraction of the core and cladding layer, which difference
preferably amounts to 0.1 units. A relatively large difference of
this kind between both indices of refraction enlarges the numerical
aperture of the light mixing element and also allows for a
"catching" of incident light beams which differ substantially from
the axis of incidence of the light entry surface of the light
mixing element and thus ensures an enlargement of the entry cone
for the radiation of the light generation device. As a further
advantage, the angular area for the total internal reflection of
the radiation transmitted in the light mixing element increases and
the reflection coefficient is improved considerably. Instead of
glasses, other transparent inorganic materials or ceramics but also
organic glasses with or without doping or transparent plastic
materials can be used for core and/or cladding areas of the light
mixing element.
[0042] In a further favorable embodiment, a coating is provided at
the outer surface of the monocore or the multicore section, but
also at both sections, if necessary, that prevents light from
exiting and is intransparent in this respect. The coating can also
be embodied so as to be metal-reflecting. Light losses within the
light mixing element can be further reduced with the help of an
additional reflective layer and at the same time the numerical
aperture of the light mixing element can be increased considerably
such that the angle of acceptance of the light entry cone of the
light mixing element can be increased considerably. A further
aspect is that the reflection of the light radiation transmitted
within the light mixing element takes place at two boundary
surfaces in this exemplary embodiment and thus every light beam
transmitted reflexively within the light mixing element is
separated into two respective sub-beams that are offset relative to
one another, into one first sub-beam which is partially totally
reflected at the boundary layer between core and cladding of the
light mixing element, and into a second light beam whose reflection
occurs at the reflective outer layer of the light mixing element,
thus improving the homogenization performance of the light mixing
element even further.
[0043] In an advantageous embodiment of the invention it is
provided that the front end of the light conductor which end is
part of the multicore section is curved at a given angle, for
example at an angle of 45 degrees relative to the optical axis of
the light source that impinges on the light conductor. Such a
design and arrangement considerably improves and facilitates the
handling in use.
[0044] In a modified embodiment of the invention it is provided to
configure the front end of the light conductor in a flexible manner
so that it can be bent depending on the case of application, for
example by 90 degrees or even more than 90 degrees. In doing so,
the handling in use in specific application situations can be
further improved and facilitated, for instance in areas of the oral
environment of a patient which are difficult to access.
[0045] It is especially favorable in any case that in the monocore
section the different colors emitted by the LED chips are mixed
properly so that properly mixed light enters the multicore section,
and no color variance is detectable on the light exit surface.
[0046] If the inventive adhesive between the monocore and multicore
section is temperature-resistant and the adhesive and the sections
have the same indices of refraction, the light conductor according
to the invention is not only removable but also autoclavable. This
plays a role particularly in the application within the scope of
dental light conductors and endoscopes.
[0047] The mounting of the light conductor relative to the light
source can be effected in any suitable manner, for example with the
aid of a bushing that also enables the light conductor to be
rotatable relative to the light source and to be removable. But all
other design variations used between the light conductor and the
light curing or lighting device, suggested heretofore in the state
of the art, can be combined with the inventive solution without any
problems. Thus, the connection interface between the light
conductor and the light curing or lighting device can be adapted to
the technical requirements in any desired way without the need for
developing special solutions therefor.
[0048] According to the invention it is favorable to use the light
conductor in a light curing device (or in a radiation source),
wherein the light conductor is preferably twistable relative to the
light curing device (or the radiation source), and is in particular
supported thereon in a removable manner. This twistability enables,
for instance, a dentist to adapt the point of exit and the
direction of exit of the light cone from the light conductor to the
localization of the tooth surface to be treated. The removability
of the light conductor enables simple autoclaving thereof,
independent of the light curing device (or the radiation
source).
[0049] The space between the light entry end of the monocore
section and the light source can be filled in any suitable manner,
for example with silicone or another transparent compound whose
index of refraction substantially corresponds to the index of
refraction of the glass used so that only very small reflection
losses arise at the media transition. It is also possible to grout
the space with the transparent compound.
[0050] Even if the use of glass both for the monocore section and
the multicore section of the light conductor is emphasized here, it
is to be understood that any other suitable materials, in
particular a transparent plastic material, can be used for
providing the light conductor.
[0051] According to a favorable embodiment of the invention it is
provided that the monocore section comprises a length that
corresponds to at least 1.5 times the diameter of the monocore
section.
[0052] According to a further favorable embodiment it is provided
that the monocore section and/or the optical fibers of the
multicore section consist of a core glass and a cladding glass.
Such a coaxial design of the light mixing element made of two
different transparent materials, preferably of two types of glass,
comprising different indices of refraction can reduce radiation
losses in connection with total internal reflection and achieve a
better guidance of the radiation. Contrary to conventional light
conductors, just like those widely used in the field of light
waveguide technology, in the light mixing element mentioned here
there is preferably a large difference between both indices of
refraction of the core and cladding layer, which difference
preferably amounts to 0.1 units. A relatively large difference of
this kind between both indices of refraction enlarges the numerical
aperture of the light mixing element and also allows for a
"catching" of incident light beams which differ substantially from
the axis of incidence of the light entry surface of the light
mixing element and thus ensures an enlargement of the entry cone
for the radiation of the light generation device. As a further
advantage, the angular area for the total internal reflection of
the radiation transmitted in the light mixing element increases and
the reflection coefficient is improved considerably.
[0053] According to a further advantageous embodiment it is
provided that there is a coating at the outer surface of the
monocore and/or the multicore section which coating prevents the
exit of light from the light conductor and/or reflects the light
impinging thereon. Light losses within the light mixing element can
be further reduced with the help of an additional reflective layer
of this kind and at the same time the numerical aperture of the
light mixing element can be increased considerably such that the
angle of acceptance of the light entry cone of the light mixing
element can be increased considerably. A further aspect is that the
reflection of the light radiation transmitted within the light
mixing element takes place at two boundary surfaces in this
exemplary embodiment and thus every light beam transmitted
reflexively within the light mixing element is separated into two
respective sub-beams that are offset relative to one another, into
one first sub-beam which is partially totally reflected at the
boundary layer between core and cladding of the light mixing
element, and into a second light beam whose reflection occurs at
the reflective outer layer of the light mixing element, thus
improving the homogenization performance of the light mixing
element even further.
[0054] According to a further advantageous embodiment it is
provided that both these sections are connected with one another at
a transition with the aid of an adhesive cement and/or a
glass-bonding adhesive that comprise a refraction index like glass.
In this way, transfer losses due to reflections at the boundary
surface can be reduced considerably because of the double rapid
change of the index of refraction
[0055] According to a further advantageous embodiment it is
provided that at least the monocore section is surrounded by a
sleeve.
[0056] According to a further advantageous embodiment it is
provided that the sleeve at least partially extends over the
transition between the monocore section and the multicore section
so that at least a portion of the multicore section that follows
the monocore section, is surrounded by the sleeve as well. This
results in a considerable stiffening of the mechanical connectino
of both light conductor sections and a transition of the flow of
power across the mechanically endangered junction between the light
conductor sections. The sleeve offers the additional advantage of
preventing a stiffness jump that reduces the load carrying capacity
of the light conductor against shear stress due to a lateral
attachment to the application location. The forces introduced are
at least partially transferred by the multicore section to the more
rigid monocore section. Nevertheless, the bending property and
flexibility of the front end of the light conductor is given on a
large scale, i.e. at said location at which the bending property is
essential in the practical application.
[0057] According to a further advantageous embodiment it is
provided that the diameter of the light conductor amounts to 6 mm
to 13 mm.
[0058] According to a further advantageous embodiment it is
provided that the monocore and/or the multicore sections are formed
in a conical manner at least over a portion of the lengths thereof.
Hereby, the light conductor can be configured to be slimmer, thus
improving the handling, for instance, in the mouth of a patient,
and/or the radiation energy, for instance, from a larger array of
diodes can be concentrated on, for instance, a smaller handling
surface.
[0059] According to a further advantageous embodiment it is
provided that the light entry side end is located at the monocore
section and that the light exit side end is located at the
multicore section. In this way, on the one hand, light mixing and
homogenization can be improved considerably and light losses can be
minimized. On the other hand, this embodiment is advantageous with
respect to the design (offset angle, crank) of the light conductor
or provision with a flexible end section.
[0060] According to a further advantageous embodiment it is
provided that the multicore section comprises a bending or cranked
section. Such a design and arrangement considerably improves and
facilitates the handling of the device in use. In doing so, light
losses are kept low.
[0061] According to a further advantageous embodiment it is
provided that a light exit surface of the multicore section extends
at an angle of 2.degree. to 90.degree. relative to a light entry
surface that runs perpendicular to the longitudinal extension of
the monocore section. Such a design and arrangement considerably
improves and facilitates the handling of the device in use.
[0062] According to a further advantageous embodiment it is
provided that the end on the light entry side of the monocore
section comprises a connection interface to a light curing device
or to the radiation source) with the aid of which a polymerizable
dental material can be cured. This ensures flexible coupling and
decoupling of the light conductor to the light curing device (or
the radiation source) wherein the light conductor can be autoclaved
separate from the device.
[0063] According to a further advantageous embodiment it is
provided that the connection interface is formed by a bushing that
can be connected with the light curing device (or the radiation
source) positively and that is fixedly connected with the end on
the light entry side of the monocore section. This represents an
embodiment that is especially advantageous with respect to
mechanics.
[0064] In an advantageous embodiment the light mixing element can
be configured in a rotationally symmetric way. Constructively, this
represents an especially functional solution that further comprises
an adaptation, to a large extent, of the optical properties of the
light mixing element with respect to the homogenization performance
at a given entire length, for instance an adaptation to the
geometrically optical radiation paths that are predefined with
respect to the light generation device, any necessary adaptations
with respect to the numerical aperture relating to the light entry
end of the light mixing element and between the light mixing
element and fiber bundle of the light conductor. Furthermore, it is
possible to adapt the size of the light entry surface of the light
mixing element to the geometry of the light generation device on
the one hand, and, for instance, concentrate the energy of the
light onto a fiber bundle comprising a smaller diameter, on the
other hand. Furthermore, for instance curved wall sections or
taperings in the cross-section of the light mixing element can
influence and modify the angles of reflection of the light beams
that are totally internally reflected within the light mixing
element and the light homogenization within the light mixing
element can be further improved by a larger number of wall
reflections of the light.
[0065] In a further advantageous embodiment the light mixing
element can be configured cylindrically and preferably comprise a
planar light entry and/or exit surface. This design of the light
mixing element can be realized technically in an especially simple
manner and thus it can be produced very cost-effectively wherein,
however, a high degree of homogenization with respect to the
intensity distribution and the spectral emission curves across the
entire exit surface of the optical fiber bundle can be achieved
surprisingly.
[0066] In a further preferred embodiment the light entry and exit
surface can comprise a polished surface and/or a surface coating or
other reflection-reducing coatings and/or is impingeable by an
immersion means. Such a polished surface whose remaining surface
roughness preferably amounts to a small fraction at most of the
wavelenght of light used improves the transmission properties of
the light mixing element and reduces light losses considerably.
Alternatively or additionally, a surface coating or other
reflection-reducing coatings can be applied to the light entry
and/or exit surfaces of the light mixing element. This measure can
further reduce light losses when light passes through the light
mixing element. As an alternative or in addition to the above
mentioned measures it is also possible to apply an immersion means
such as an immersion oil, for instance silicone oil, to the
corresponding surfaces of the light mixing element such that the
gap between the light mixing element and, for instance, the fiber
bundle of the light conductor or the protective glass across light
diodes or semiconductor radiation sources comprising associated
reflectors is filled completely with this immersion means and thus
instead of a solid-air-solid phase transition a solid-liquid-solid
phase transition takes place. The index of refraction of the
immersion means which is higher relative to that of air makes
possible to further reduce light losses by boundary surface
reflection and then again adaptations of the numerical aperture of
the optical components connected to one another can be caused.
[0067] In a further preferred embodiment the light mixing element
comprises at least one light-conducting core, preferably made of a
core glass, comprising a first refraction index and a
light-conducting cladding, preferably made of cladding glass,
comprising a second refraction index, wherein the second refraction
index is smaller--preferably by at least 0.1 units--than the first
refraction index. Such a coaxial design of the light mixing element
made of two different transparent materials, preferably of two
types of glass, comprising different indices of refraction reduces
radiation losses in connection with total internal reflection and
achieves a better guidance of the radiation. Contrary to
conventional light conductors, just like those widely used in the
field of light waveguide technology, in the light mixing element
mentioned here there is preferably a large difference between both
indices of refraction of the core and cladding layer, which
difference preferably amounts to 0.1 units. A relatively large
difference of this kind between both indices of refraction enlarges
the numerical aperture of the light mixing element and also allows
for a "catching" of incident light beams which differ substantially
from the axis of incidence of the light entry surface of the light
mixing element and thus ensures an enlargement of the entry cone
for the radiation of the light generation device. As a further
advantage, the angular area for the total internal reflection of
the radiation transmitted in the light mixing element increases and
the reflection coefficient is improved considerably. Instead of
glasses, other transparent inorganic materials or ceramics but also
organic glasses with or without doping or transparent plastic
materials can be used for core and/or cladding areas of the light
mixing element.
[0068] In a further preferred embodiment the light mixing element
can comprise a reflection-enhancing coating or a reflective sleeve
at its circumferential surface. Light losses within the light
mixing element can be further reduced with the help of an
additional reflective layer of this kind and at the same time the
numerical aperture of the light mixing element can be increased
considerably such that the angle of acceptance of the light entry
cone of the light mixing element can be increased considerably. A
further aspect is that the reflection of the light radiation
transmitted within the light mixing element takes place at two
boundary surfaces in this exemplary embodiment and thus every light
beam transmitted reflexively within the light mixing element is
separated into two respective sub-beams that are offset relative to
one another, into one first sub-beam which is partially totally
reflected at the boundary layer between core and cladding of the
light mixing element, and into a second light beam whose reflection
occurs at the reflective outer layer of the light mixing element,
thus improving the homogenization performance of the light mixing
element even further.
[0069] In a further preferred embodiment the diameter of the light
mixing element amounts to preferably between 2 mm and 20 mm,
particularly preferably between 6mm and 15 mm, in particular
between 8mm and 13 mm, and the length of the light mixing element
is greater than 0.5 times the diameter, in particular greater than
0.8 times the diameter, and preferably smaller than 5 times the
diameter, in particular smaller than twice the diameter of the
light mixing element. These dimensions represent an especially
favorable constructive dimensioning with respect to the geometry of
the light mixing element. In this way, an optimal mixing of light
and homogenization can be achieved at minimized external
dimensions. Additionally, the given diameters take account of the
geometrical optical conditions with respect to the size of the
light generation device and the entry diameter of the fiber bundle
of the light conductor typically used in the given fields of
medicine and dental medicine.
[0070] In a further preferred embodiment the light mixing device
can comprise a connection interface--preferably made of a highly
temperature resistant plastic material, in particular a sulfone,
etherketone or imid plastic material or plastic composite
material--to which the light mixing element is connected,
preferably non-positively and/or in a firmly bonded manner, wherein
the connection interface is connectable to one of the two,
preferably in a self-aligned manner relative to the light conductor
and/or the light generation device. This represents an especially
advantageous design for mounting the light mixing element within
the beam path of the lighting device or the light curing device. In
doing so, the connection interface can be connected to the light
conductor and/or to the light generation device at or in the
housing of the lighting or light curing device wherein the
connection interface is preferably configured such that it adjust
itself with respect to the light conductor and/or the light
generation device and is thus positioned exactly within the beam
path without the need for additional mounting and adjusting
efforts. In this connection, the connection interface is produced
at least to a large extent preferably from a highly temperature
resistant plastic material, in particular a sulfone, etherketone or
imid plastic material or plastic composite material. In this way,
the required temperature resistance, mechanical strength and
dimensional stability of the connection interface can be maintained
on the one hand, and due to the elastic properties of the
corresponding plastic materials a receptivity for thermal expansion
movements and a limitation of thermal stresses is achieved, on the
other hand. At the same time, a connection interface of this kind
made of such a plastic material enables the targeted use of press
fits and/or preloads between the connection interface and the light
mixing element on the one hand which in this case can be connected
to the connection surface preferably non-positively and/or in a
firmly bonded manner, and on the other hand between the connection
interface and the connection component to which the connection
interface can be attached free of play and securely with respect to
changes in temperature using a press fit and/or preloads.
[0071] In a further preferred embodiment the light entry and/or
light exit surfaces of the light mixing element can be formed in an
aplanar manner. Thus, it is, for instance, possible to configure
the respective surfaces of the light mixing element in a slightly
wavelike or undulated manner, for instance like the concentric,
circular waves that arise in a water surface after a stone's throw.
As a result of such a surface design, incoming and outgoing light
beams--in contrast to a planar surface--are deflected slightly in
an alternating manner in the radial direction of the light mixing
element and are spread across a larger angular area, thus
considerably increasing the light mixing effect of the light mixing
element. A similar effect could be achieved with a faceted surface
design or with a Fresnel cut of the respective surfaces of the
light mixing element at the front side. Furthermore, it is also
possible to configure the respective surfaces of the light mixing
element convexly or concavely, in order to thus increase the angles
of acceptance for the light entry cone or undertake adaptations
with respect to the numerical entry and/or exit aperture and in
this way to, for instance, limit the divergence of the exit beam
from the light mixing element and adapt it to the numerical
aperture of the fiber bundle.
[0072] In a further preferred embodiment the light mixing device
can be provided and configured for retrofitting a lighting device
or a light curing device, and is mountable between the light
conductor and the housing of the light generation device or the
light curing device--preferably in a bushing. This creates the
possibility of retrofitting existing lighting devices or light
curing devices which are being used with the advantageous inventive
light mixing device and thus improve their efficiency and retrofit
them with the inventive advantages.
[0073] Further advantages, details and features emerge from the
following description of two exemplary embodiments of the invention
in conjunction with the drawing, in which:
[0074] FIG. 1 shows a schematic sectional view through an
embodiment of a light conductor according to the invention; and
[0075] FIG. 2 shows a schematic sectional view through a further
embodiment of a light conductor according to the invention.
[0076] The light conductor 10 illustrated in FIG. 1 comprises a
monocore section 12 and a multicore section 14. Both sections 12
and 14 have the same outer diameter and merge with one another in a
flush manner at a transition 16. The monocore section 12 is located
adjacent to a light entry side end 18 of the light conductor 10,
and the multicore section 14 is located adjacent to a light exit
side end 20 of the light conductor.
[0077] The monocore section extends in a straight manner and in the
illustrated embodiment takes up a length of about three quarters of
the length of the light conductor. The multicore section 14 takes
up the last, i.e. the front quarter of the light conductor and is
curved adjacent to the end 20, and in fact by about an angle of 60
degrees.
[0078] A light exit axis 22 correspondingly extends at an angle of
approximately 60 degrees relative to a light entry axis 24.
[0079] Both the monocore section 12 and the multicore section 14
comprise at the outside thereof a cladding 26 (not shown in detail)
that is formed like a coating and that reflects light radiation
impinging thereon from inside back inwards.
[0080] The monocore section is formed as a massive, rod-shaped
light-conducting rod that is surrounded by the cladding 26. In
contrast to that, the multicore section 14 consists of a plurality
of light-conducting or optical fibers 30, for example 100 to 500
individual light-conducting fibers, as schematically indicated in
FIG. 1. In the illustrated embodiment the multicore section 14,
too, is formed in a rigid manner.
[0081] At the transition 16, both sections 12 and 14 are connected
with one another with the aid of a glass-bonding adhesive. The
light-conducting rod of the monocore section, the light-conducting
or optical fibers 30 of the multicore section 14, and the
glass-bonding adhesive (not shown) have the same indexes of
refraction, respectively, so that reflections at the phase
boundaries are avoided, if possible.
[0082] The monocore section 12 comprises at its light entry side
end 18 a plug-in sleeve 32. Via said plug-in sleeve 32, the light
conductor 10 is supported in a plug-in manner at a corresponding
socket of a light curing device, which socket is formed in a manner
known per se and is not illustrated here.
[0083] The light entry into the light entry side end 18 takes place
via a light source 34 that comprises a plurality of individual LED
chips, some of which are illustrated in FIG. 1, namely chips 36 and
38. The light exit of the light source 34 is bundled in a manner
known per se by means of a reflector 40. The space 42 between the
light source 34 and the end 18 is filled with silicone or another
compound whose index of refraction approximates that of glass.
[0084] The chips 36 and 38 are installed on a cooling element 44
that dissipates the heat generated thereat.
[0085] The chips 36 and 38 comprise different emission maxima and
preferably can be controlled separately.
[0086] When all LED-chips of the light source 34 are switched on,
the space 42 is filled with light of different colors. In the
monocore section 12 there is a good light mixing in any case so
that white light is fed into the optical fibers 30.
[0087] FIG. 2 illustrates a further embodiment of the inventive
light conductor. In contrast to the embodiment according to FIG. 1,
the multicore section 14 is configured so as to be flexible in this
example. In the exemplary embodiment illustrated, the optical light
exit axis 22 extends at an angle of approximately 45 degrees
relative to the light entry axis 24; it is to be understood,
however, that any other position, and even a redirection of nearly
180 degrees, is possible as well.
[0088] In this exemplary embodiment, the transition 16 is
surrounded by a sleeve 50 that serves to stiffen the transition and
that prevents the adhesive cement provided at the transition from
failing due to a strong mechanical load.
[0089] As can be seen in FIG. 2, the light-conducting rod may be
rotated as a whole by means of the light conductors 10; this is
also possible in the case of the embodiment according to FIG. 1. In
the embodiment according to FIG. 2 only one single chip 36 is
provided as a light source 34, said chip being centrally installed
on the cooling element 44. The space 42 is quite small which is
already favorable due to the fact that silicone typically produces
higher light losses than glass. In this respect, the space 42
according to FIG. 1 is illustrated in an exaggeratedly long manner;
in practice, the length of the space 42 amounts to, for example,
one third or less of the diameter of the light conductor 10.
[0090] According to FIG. 1, the diameter of the light conductor
amounts to 12 mm and according to FIGS. 2 to 5 mm, whereas it is to
be understood that the diameter of the light conductor may take any
suitable values without departing from the scope of the invention.
This also applies to the length distribution between the monocore
and multicore section.
[0091] For example, the monocore section alone may be at least
eight times longer than its diameter. In the embodiment according
to FIG. 2, the length of the multicore section 14 amounts to
approximately two fifth of the total length of the light conductor
10, and that of the monocore section correspondingly amounts to
three fifth.
[0092] All details and values of the embodiment described are only
to be understood as being exemplary and can thus be amended within
the scope of protection of the claims. Even if the invention is
described here in conjunction with the use in a dental light curing
device, it is to be understood that the basic ideas of the
invention are also used advantageously in other apparatuses
requiring light conductors, in particular in medical devices such
as endoscopes or other light sources, for instance, for medical
research, the use in a laboratory or industrial purposes.
* * * * *