Semiconductor radiation source and light curing device

• US 7,595,513 B2
• Filed: 03/23/2007
• Issued: 09/29/2009
• Est. Priority Date: 04/03/2006
• Status: Active Grant

• Current Assignee: Ivoclar Vivadent AG
• Original Assignee: Ivoclar Vivadent AG
• Inventors: Plank, Wolfgang, Senn, Bruno
• Primary Examiner(s): Lee; Calvin
• Application Number:
  US11/728,252
• Publication Number:
  US 20070228516A1
• Time in Patent Office: 921 Days
• Field of Search: 257 79- 85, 257/95, 257/98, 257E33056-E33059, 438 29- 31
• US Class Current: 257/98
• CPC Class Codes: A61C 19/003 Apparatus for curing resins by radiation
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/19107 off-chip wires
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H01L 33/64 Heat extraction or cooling elements

Abstract

Provision is made of a semiconductor radiation source having a base body on which at least two LED chips are mounted, at least one chip of which is connected to a series resistor which can be adjusted. The LED chips (12, 14) are fitted to the base body (24) using a thermally conductive connection and at least one printed circuit board (30) which bears the series resistor (40, 42) is also mounted on the base body (24).

Claims

1. A semiconductor radiation source having:

a base body;

at least two centrally arranged LED chips directly mounted to the base body using a thermally conductive connection, wherein at least one LED chip is connected to an adjustable resistor; and

at least one printed circuit board mounted on the base body, and wherein said adjustable resistor is mounted on the printed circuit board.

2. The radiation source as claimed in claim 1, wherein the printed circuit board projects into free areas which extend laterally beside the chips.

3. The radiation source as claimed in claim 2 wherein the printed circuit board is arranged between the edge of the base body and the LED chips.

4. The radiation source as claimed in claim 1, wherein a first LED chip is arranged on an optical axis and a plurality of further LED chips are radially arranged outside the first LED chip in such a manner that they are symmetrical with respect to one another and surround the first LED chip in the manner of a cross or star.

5. The radiation source as claimed in claim 4, wherein the printed circuit board also extends into the areas located between the limbs of the cross.

6. The radiation source as claimed in claim 1, wherein a reflector element is arranged between two mutually adjacent LED chips, and is supported on the base body and/or the printed circuit board and/or the LED chips.

7. The radiation source as claimed in claim 6, wherein the reflector element has two reflecting areas which run essentially obliquely, each reflecting area reflecting radiation emanating from the adjacent LED chip.

8. The radiation source as claimed in claim 7, wherein the reflecting areas, when viewed in the direction of the optical axis, essentially extend in a manner corresponding to the height of the printed circuit board or project beyond the printed circuit board and are of slightly concave or parabolic shape.

9. The radiation source as claimed in claim 1, wherein a plurality of reflector elements are connected to one another so as to form a grating reflector, the grating reflector being supported on the base body and/or the printed circuit board and/or the LED chips.

10. The radiation source as claimed in claim 1, wherein the LED chips are fitted in a central region of the base body, essentially at the height of to printed circuit board.

11. The radiation source as claimed in claim 1, wherein radiation absorbers which are connected to the base body using thermally conductive connections extend between external LED chips, and the printed circuit board.

12. The radiation source as claimed in claim 11, wherein the radiation absorbers extend at least over the width of the LED chips and have a greater height than the LED chips, preferably approximately 1.5 to 5 times the height, and particularly preferably approximately twice the height, of the LED chips.

13. The radiation source as claimed in claim 12, wherein a closed space which has a transparent or translucent liquid or gelatinous substance which extends between the LED chips, the spacer and the cover lens.

14. The radiation source as claimed in claim 11, wherein the radiation absorbers are simultaneously of heat-insulating design and are composed of ceramic.

15. The radiation source as claimed in claim 1, wherein a cover lens is arranged in the beam path downstream of the LED chips and an annular or tubular spacer is provided for said lens, and wherein the spacer is supported on the printed circuit board and/or the base body.

16. The radiation source as claimed in claim 15, wherein at least one conductor track of the printed circuit board runs through under the spacer.

17. The radiation source as claimed in claim 15, wherein a converging lens whose diameter is larger than the diameter of the cover lens is arranged in the beam path downstream of the cover lens.

18. The radiation source as claimed in claim 15, wherein a reflector is arranged in the beam path downstream of the LED chips at a distance from the latter and is also arranged downstream of the cover lens in the beam path.

19. The radiation source as claimed in claim 18, wherein a light guide is arranged in the beam path downstream of the reflector.

20. The radiation source as claimed in claim 1, wherein the base body is at least partially composed of copper and/or is at least partially coated with gold or nickel/gold.

21. The radiation source as claimed in claim 1, wherein the LED chips emit light at different wavelengths.

22. The radiation source as claimed in claim 1, wherein said printed circuit board extends away from the centrally arranged LED chips to the outside, to the peripheral region of the base body.

23. The radiation source as claimed in claim 1, wherein the at least one series resistor extends from the LED chips to the printed circuit board.

24. The radiation source as claimed in claim 23, wherein the series resistors are filled such that they are freely accessible outside the supporting element and can be adjusted there.

25. The radiation source as claimed in claim 24, wherein the series resistors are connected to the printed circuit board via resistance contact areas.

26. The radiation source as claimed in claim 24, wherein the series resistors are in the form of a resistance track whose width can be reduced, at least one point for example by means of laser trimming to change the resistance of the resistor.

27. The radiation source as claimed in claim 24, wherein the series resistor is printed onto the printed circuit board or is applied using thick-film technology and has a compound or paste containing conductive particles composed of graphite.