AU691130B2

AU691130B2 - Light curing device

Info

Publication number: AU691130B2
Application number: AU70571/96A
Authority: AU
Inventors: Jurgen Mertins
Original assignee: Ivoclar AG
Current assignee: Ivoclar AG
Priority date: 1995-11-17
Filing date: 1996-11-04
Publication date: 1998-05-07
Anticipated expiration: 2016-11-04
Also published as: JP2995160B2; DE19542985C2; EP0774239A2; EP0774239A3; ATE218050T1; JPH09168551A; AU7057196A; CA2189498A1; EP0774239B1; CA2189498C; DE19542985A1; DE59609257D1

Abstract

The handheld equipment incorporates a lamp with a light guide (12), a collector lens (14) and a reflector (16) in a common housing (18). The light guide has a gradual taper over several centimetres for access to all relevant areas of the patient's mouth. The plano-convex lens is made of infrared-absorbent glass with its convex face turned towards the lamp and coated with an edge filter (36) by vapour deposition. This reflects and scatters infrared radiation of all wavelengths in excess of its cut-off value.

Description

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: a a a sc a I a r a e e a a Name of Applicant: Ivoclar AG Actual Inventor(s): Jurgen Mertins Address for Service: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: LIGHT CURING DEVICE Our Ref 470735 POF Code: 1502/77261 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): -1- LIGHT CURING DEVICE Background of the Invention The present invention relates to a light curing device, especially for irradiating curable dental compositions, with a light source and a light guiding device, such as a light guide, having a light receiving opening, whereby in the path of the light beam between light source and light receiving opening a focusing lens is arranged. The device is especially used for curing dental plastic materials that are polymerizable under the effect of light.

Such a light curing device is known from German Offenlegungsschrift 32 37 510. In such a light curing device the light source is surrounded by a reflector which focuses the emitted light radiation onto a focusing lens. The piano-convex focusing lens the planar surface of which is facing the light source, is designed to focus the light beam onto the light receiving opening f of the light guide. In the known light curing device spectral lamps are used as light sources, which are relatively large and heavy in order to be able to introduce monochromatic light radiation into the light guide.

In order to facilitate handling of the device, the known light curing device has a flexible light guide of a length of 2 meters.

With this construction, the operator is thus limited in his -1 c A.G.- P 195 985.0 2657-11-17.789 Ivoclar A.G.

moveability by the connection via the light guide. Furthermore, with a comparatively long and flexible light guide there is always present the danger of kinking. Even though possible external damages cannot be seen, the resulting light efficiency of the light guide is considerably reduced without being apparent to the operator.

However, this carries the considerable risk that a light curing step is not completed so that the used dental material is not cured according to specification.

Furthermore, hand-held devices are known, for example, from German Offenlegungsschrift 42 11 230. With such hand-held devices it is conventional to use for the comparatively compact arrangement light sources of high energy density which results often in thermal problems. Despite the comparatively high 15 energy expenditure, the light efficiency for these hand-held devices is still S" improvable.

It is therefore an object of the present invention to provide an improved .light curing device.

-o I, 'WINWORDJAELISSABRAB.JODELETESPECi705?l-6 DOC 0/7 SUMMARY OF THE INVENTION According to the invention there is provided a hand-held light curing device including: a light source; a light guiding device having a light receiving opening; a lens arrangement including a focusing leans positioned between said light source and said light guiding device; said focusing lens including a cut-off filter at a surface thereof said cut-off filter facing said light source.

Preferab'y, the cut-off filter is vapor-deposited on the surface.

Advantageously, the focusing lens is a piano-convex lens having convex surface, wherein the convex surface faces the light source.

Advantageously, the hand-held curing device further includes a reflector including an inner surface with reflective coating. The reflector is positioned 20 adjacent to the focusing filter and widens conically in a direction toward the light Ssource.

The focusing lens preferably includes heat absorbing glass.

The focusing lens is preferably spaced from the light guiding device, C WINWORDWIELISSABRADWOOELErEPECn757t.

DOC

4 and the focus of the focusing lens coincides with the light receiving opening or is positioned within the light guiding device behind the light receiving opening.

Advantageously, the light source is a compact lamp having a high light efficiency relative to the size of the lamp and relative to the amount of electric energy supplied to the lamp.

Expediently, the lamp is a halogen lamp.

The lens arrangement may further include a concave-convex lens or a biconvex lens.

The cut-off filter preferably allows light below a selected wavelength 15 threshold to pass.

The cut-off filter is preferably opaque to infrared radiation.

The cut-off filter preferably has reflective properties with respect to the 20 blocked radiation.

Surprisingly, with the inventive measures a favorable light efficiency with respect to light curing can be achieved despite the embodiment as a compact, hand-held device. Even though the compact halogen universal lamps are used, which are considerably less expensive than spectral lamps, the light efficiency is surprisingly good and does not result in an undesirable heating within the mouth of the paiient or with respect to the dental material to be cured. Apparently, the cut-off filter C WNWORD'MELISSA&BRADINODELETESPECI70571 96 DOC -r o vapor-deposited onto the focusing lens has an especially good reflective effect for undesirable radiation without impairing the light radiation emitted by the halogen lamp. The cut-off filter has an especially good transmissivity for the frequency ranges required for polymerization. Advantageously, a light guide of a comparatively large diameter can be used whereby weight and handling problems of light guides of greater diameters are substantially reduced with respect to known light curing devices since the inventively used light guide extends only over a length of a few centimeters instead of being 1 to 2 meters long.

The inventive light curing device is especially advantageously realized as a hand-held device. Individual advantages result, however, also in an embodiment as a stationary device with flexible light guide.

~The risk of unnoticed reduction of the light efficiency due to breakage of the light guide is practically prevented since the light guide can optionally be surrounded by a metal tube so as to be especially well protected since it must not be flexible.

According to a preferred embodiment, it is suggested to apply the cut-off filter onto the convex surface of the focusing lens.

Inasmuch as heat radiation is reflected by the cut-off filter, the heat radiation is diverted which is espelially favorable with respect P 195 42 985.0 2657-11-17.789 Ivoclar A.G.

to heat dissipation.

In another preferred embodiment, the inventive light curing device includes a reflector which is positioned adjacent to the focusing lens and/or cut-off filter whereby the reflector cone extends between the light source and a cut-off filter and/or the focusing lens and whereby the cone angle opens toward the light source. This reflector increases the light efficiency in that the radiation emitted by the light is reflected and guided toward the focusing lens and improves in a double function at the same time the heat dissipation of the cut-off filter, especially when the conical reflector sleeve comprises a metallic reflective layer.

According to another preferred embodiment, the focusing lens is a planoconvex lens the convex surface of which is especially facing the light source.

This embodiment is especially favorable with respect to mounting and with respect to light introduction into the light guide. Light beams reflected by the light receiving opening are immediately reflected back at the planar surface of the focusing lens so that they can reenter the light guide.

20 When the focusing lens is made of heat-absorbing glass, the penetrating infrared radiation is mostly absorbed and the temperature is increased. In this context it is especially favorably RA4~ E

,C

N W~ORDAELSSABRAOCDELETEZSPECIX707l -96 DOC I when the focusing lens is spaced from the light guide so that there is no risk that the light guide could be heated to unacceptable limits. The absorption properties furthermore act to compensate residual heat whereby it is understood that in this embodiment it may be advantageors to apply the cut-off filter at the surface facing the light guide in order to prevent the emission of heat radiation in the direction of the light guide.

It is understood that, if necessary, both sides of the focusing lens can be provided with vapor-deposited cut-off filters.

Even though, in general, other methods for application of the cut-off filter are possible, it is preferred to vapor-deposit the cut-off filter. This allows for uniform and minimal layer thickness with optimal minirnal transmission damping in the transmissive range of the filter.

*irr It is understood that, if needed, the focusing lens can be used in combination with iurther lenses in order to improve the optical properties.

Brief Description of the Drawings ~The object and advantages of the present invention will appear more clearly from the following specification in conjunction with the accompanying drawings, in which the only Figure shows a portion of the inventive light curing device in section, -7- P 195 42 985.0 2657-11.17.789 IvoclarA.G.

representing the light guide and the focusing lens.

Description of Preferred Embodiments The present invention will now be described in detail with the aid of several specific embodiments utilizing the only Figure.

As apparent from the only Figure, the inventive light curing device 10 comprises a light guide 12, a focusing lens 14, and a reflector 16 which are housed in a common housing 18. The housing 18 furthermore supports a non-represented light source which can be optionally provided with a well known reflector and which would be positioned to the left in the drawing. The light guide 12 is only partly represented in the drawing and extends e. over a length of a few centimeters, optionally with a slightly bent tip, in order to allow easy access to any area within the mouth of a patient.

The light curing device is a hand-held device and has a construction as is, for example, known from German Offenlegungsschrift 42 11 230, the complete disclosure of which is herewith explicitly included by reference. The housing 18 comprises a plurality of vent openings 20, 22 which extend substantially annularly coaxially to the optical axis 24 and which are interrupted by ribs 26, 28 which are uniformly distributed over the circumference.

-8- P 195 42 985.0 2657-11-17.789 IvoclarA.G.

~I

The housing is provided in a manner known per se with a fan which is arranged behind the lamp and operated such that the vent openings 20, 22 act as air inlet openings. Thus, relatively cold air passes along the focussing lens 14 and the reflector 16 and provides a comparatively good cooling effect thereat. The focusing lens 14 is supported in the housing with a separate securing sleeve 30 which also supports the light guide 12. The light guide 12 is supported within the securing sleeve 30 by a socket 32. The arrangement of focusing lens 14 and light guide 12 within the securing sleeve 30 is selected such that the light receiving opening 34 of the light guide 12 is clearly spaced from the focusing lens 14. In the represented embodiment the spacing is greater than the maximal thickness of the focusing lens 14. The e focus of the focusing lens 14 is positioned somewhat behind the ~light receiving opening 34 within the light guide 12.

The focusing lens 14 is a piano-convex lens whereby the planar surface faces the light guide and the convex surface faces the light source. On the side facing the light source a cut-off filter oo. is vapor-deposited onto the lens. In addition, the lens is comprised of heat-absorbing glass which absorbs to a large extend infrared radiation. Due to this arrangement, it is achieved that, despite the directly adjacent positioning to the light guide 12, -9- P 195 42 985,0 2657-11-17.789 Ivoclar A.G.

practically only light with the desired wave;ength range can enter the light guide 12. For example, the cut-off filter Lan be embodied such that undesirable UV radiation is filtered out. The rounded embodiment of the cut-off filter 36 also results in that the blocked radiation is reflected over a large surface area and distributed.

The reflected radiation impinges on the reflector 16 which is positioned within the direct air flow at the flow channel 38 and which is thus well cooled. Furthermore, the cut-off filter 36 and thus the focusing lens 14 are positioned in thermal vicinity of the reflector 16; via the vent openings 22 an additional flow channel which is directly adjacent is opened which participates in the cooling effect.

The support of the lens 14 is such ti.at it is clamped with a securing ring 40, that is optionally elastic, between the securing sleeve 30 and the reflector 16. The reflector 16 is screwed from the interior onto the housing 18 so that the screw connection supports in sequence the securing sleeve 30, the focusing lens 14, the securing ring 40, and the reflector 16 at the corresponding securing flange 42 of the housing.

As can be seen in the drawing, the light radiation emitted by the light source is refracted partially directly, according to the course of the light beam 44, and then enters, parallel to the optical P 195 42 985.0 2657-11-17.789 Ivoclar A.G.

axis 24, the light guide 12. Partly, the radiation is reflected at the reflector 16, as indicated by the light beam 46, enters the lens and, after corresponding refraction within the focusing lens 14, exits parallel to the optical axis 24. This is of course only true for light beams with wavelength which pass through the cut-off filter 36.

In the shown embodiment, the reflector 16 is a metal oart and has good heat conducting properties. However, it is understood that instead a plastic part with inner reflective layer can be used. It is advantageous to widen the reflector in the direction toward to the light source.

o Instead of the focusing lens 14 it is !so possible to use focusing lenses of a different design or to us a corresponding lens arrangement. The focusing lens is provided in a suitable manner I: with a cut-off filter which prevents that light or electromagnetic radiation with an undesirable wavelength can enter the light guide *too..

:12.

The present invention is, of course, in no way restricted to the specific disclosure of the specification and drawings, but also encompasses any modifications within the scope of the appended claims.

-11 P 195 42 985.0 2657-11-17.789 Ivoclar A.G.

Claims

1. A hand-held light curing device including: a light source; a light guiding device having a light receiving opening; a lens arrangement including a focusing leans positioned between said light source and said light quiding dev'ice; said focusing lens including a cut-off filter at a surface thereof said cut-off filter facing said light source.

2. A hand-held light curing device according to claim 1, wherein said cut-off filter is vapor-deposited on said surface. 1"

3. A hand-held light curing device according to claim 1 or claim 2, wherein said focusing lens is a piano-convex lens having a convex surface, wherein said convex surface faces said light source

4. A hand-held curing device according to any one of the preceding claims, further including a reflector including an inner surface with reflective coating, said 20 reflector positioned adjacent to said focusing lens and widening conically in a direction toward said light source.

5. A hand-held light curing device according to any one of the preceding claims, wherein said focusing lens includes a heat-absorbing glass.

6. A hand-held light curing device according to any one of the preceding claims, wherein said focusing lens is spaced from said light guiding device and wherein a focus of said focusing lens coincides with said light receivil, opening.

7. A hand-held I;ght curing device according to any one of claims 1 to wherein said focusing lens is spaced from said light guiding device and wherein a focus of said focusing lens is positioned within said light guiding device. C 'V~NWORDMEfLSACRA IN3EkETCESPECOSI 90 DOC .1. 13

8. A hand-held light curing device according to any one of the preceding claims, wherein said light source is a compact lamp having a high light yield relative to a size of said lamp and relative to an amount of electric energy supplied to said lamp.

9. A hand-held light curing device according to claim 8, wherein said lamp is a halogen lamp.

A hand-held light curing device according to any one of the preceding claims wherein side lens arrangement further includes a concave-convex lens.

11. A hand-held light curing device according to any one of claims 1 to 9 wherein said lens arrangement further includes a biconvex lens.

12. A hand-held light curing device according to any one of the preceding claims, wherein said cutt-off filter allows light below a selected wavelength threshold to pass.

13. A hand-held light curing device according to claim 12, whereirn said cut-off 20 filter is opaque to infrared radiation.

14. A hand-held light curing device according to any one of the preceding i claims wherein said cut-off filter has reflective properties with respect to blocked radiation. A hand-held light curing device substantially as herein before described and illustrated. DATED: 3 March 1998 PHILLIPS ORMONDE FITZPATRICK Attorneys for: IVOCLAR AG Abstract of the Disclosure A hand-held light curing device has a light source and a light guiding device having a light receiving opening. A lens arrangement with a focusing lens is positioned between the light source and the light guiding device. The focusing lens has a cut- off filter at a surface thereof. The cut-off filter is preferably vapor- deposited on the surface. Preferably, the focusing lens is a plano- convex lens having a convex surface facing the light source. S S. S SSS *5 S S 5455 P 195 42 985.0 2657-11-17.789 Ivoclar A.G. I