High intensity light source for a machine vision system and method of making same

• US 20060039141A1
• Filed: 08/01/2005
• Published: 02/23/2006
• Est. Priority Date: 08/18/2004
• Status: Active Grant

• Current Assignee: Advanced Illumination, Inc. (China TransInfo Technology Co., Ltd.)
• Original Assignee: Advanced Illumination, Inc. (China TransInfo Technology Co., Ltd.)
• Inventors: Thrailkill, John E., Thrailkill, William
• Granted Patent: US 7,775,679 B2
• Time in Patent Office: Days
• US Class Current: 362/227
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: G01N 2201/062 LED's
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

A light source for machine vision applications includes a housing having a thermally conductive base plate which supports an array of high intensity LEDs. The LEDs are fitted with secondary lenses which are aimed such that the light beams from the LEDs illuminate fixed targets having a predetermined spatial relationship so that the light source produces a very uniform light field. After the lenses are aimed, they are secured in the desired position relative to their associated LEDs using a UV-curable adhesive.

Claims

1. A light source for use in a machine vision system for substantially uniformly illuminating a predetermined area, comprising:

a base plate having a first face;

a plurality of high intensity light emitting diodes mounted at spaced apart positions to said base plate so that a light-emitting end of each of said diodes extends from the first face of said base plate;

a secondary lens mounted over the light-emitting end of each of said diodes;

each of said secondary lenses being adjusted relative to the light-emitting end of its associated diode so that, when its associated diode is illuminated, light therefrom is focused on a target surface spaced from said diode substantially in one of a plurality of illumination sectors according to a predetermined lighting pattern.

2. The light source of claim 1 in which each of said secondary lenses is initially moveable relative to the light-emitting end of its associated diode and is secured thereto after it is adjusted.

3. The light source of claim 1 in which said base plate is thermally conductive.

4. The light source of claim 3 in which each of said diodes includes a heat sink in thermal contact with said base plate.

5. The light source of claim 1 in which the light-emitting end of each of said diodes includes a primary lens having a curved end surface, and in which each of said secondary lenses is mounted over the primary lens of one of said diodes and includes an interior surface spaced from and having a curvature substantially corresponding to that of the primary lens over which it is mounted.

6. The light source of claim 2 further including a curable adhesive between each of said secondary lenses and the light-emitting end of its associated diode which is cured to secure the secondary lens in place after it is adjusted.

7. The light source of claim 6 in which said base plate includes a plurality of recesses around each of said diodes mounted thereto and in which the curable adhesive extends into one or more of said recesses.

8. The light source of claims 6 and 7 in which said adhesive is a liquid light-curable adhesive which is cured by exposing the adhesive to light.

9. The light source of claim 1 further including a diffuser spaced a fixed distance from the light-emitting ends of said diodes on said base plate to optimize the light field uniformity from said light source.

10. The light source of claim 9 further including a housing for holding said base plate and said diffuser.

11. The light source of claim 1 in which each of said diodes has an intensity in the range of about 1 to about 5 watts.

12. A method of constructing a light source for use in a machine vision lighting system, said light source having a plurality of high intensity light emitting diodes mounted on a base plate for substantially uniformly illuminating a predetermined area, comprising the steps of:

mounting each of the diodes at spaced apart positions on the base plate so that a light-emitting end of each diode extends from a first face of the base plate;

providing a secondary lens over the light-emitting end of each of the diodes, each secondary lens being moveable relative to the light-emitting end of each diode in three dimensions within a predetermined range of movement;

providing an alignment fixture for receiving the base plate and having a target surface spaced from the first face of the base plate and in optical communication with the light emitting end of each diode;

defining on the target surface a plurality of illumination sectors;

selectively illuminating one of the diodes and, while illuminated, adjusting the secondary lens relative to the light-emitting end of the illuminated diode so that light from the illuminated diode is focused substantially in one of the plurality of illumination sectors according to a predetermined lighting pattern;

repeating the selectively illuminating step for the other diodes on the base plate; and

securing each secondary lens relative to its associated diode after it is adjusted.

13. The method of claim 12 further including the step of temporarily securing each secondary lens relative to the light-emitting end of its associated diode after it is adjusted.

14. The method of claim 13 in which the securing step comprises permanently securing the secondary lens relative to the light-emitting ends of their associated diodes after they are adjusted.

15. The method of claims 13 and 14 in which the securing steps comprise applying an uncured adhesive between the secondary lenses and the light-emitting ends of their associated diodes and then curing the adhesive.

16. The method of claim 15 in which the uncured adhesive is a liquid light-curable adhesive and the curing step comprises exposing the adhesive to light.