Patent Grant
8101434
This invention relates to lighting fixtures and, more particularly, to methods of assembling lighting fixtures using LED emitters.
In recent years, the use of light-emitting diodes (LEDs) for various common lighting purposes has increased, and this trend has accelerated as advances have been made in LEDs and in LED-array bearing devices, often referred to as “LED modules.” Indeed, lighting applications which have been served by fixtures using high-intensity discharge (HID) lamps and other light sources are now increasingly beginning to be served by LED modules. Such lighting applications include, among a good many others, roadway lighting, parking lot lighting and factory lighting. Creative work continues on development of lighting fixtures utilizing led modules. It is the latter field to which this invention relates.
High-luminance light fixtures using LED modules as light source present particularly challenging problems. High costs due to high complexity becomes a particularly difficult problem when high luminance, reliability, and durability are essential to product success. Keeping LEDs and LED-supporting electronics in a water/air-tight environment may also be problematic, particularly when, as with roadway lights and the like, the light fixtures are constantly exposed to the elements. Use of a plurality of LED modules presents further challenges.
Yet another cost-related challenge is the problem of achieving a high level of adaptability in order to meet a wide variety of different luminance requirements. That is, providing a fixture which can be adapted to give significantly greater or lesser amounts of luminance as deemed appropriate for particular applications is a difficult problem. Light-fixture adaptability is an important goal for LED light fixtures.
Dealing with heat dissipation requirements is still another problem area for high-luminance LED light fixtures. Heat dissipation is difficult in part because high-luminance LED light fixtures typically have a great many LEDs and several LED modules. Complex structures for module mounting and heat dissipation have sometimes been deemed necessary, and all of this adds to complexity and cost.
In short, there is a significant need in the lighting industry for an improvement in manufacturing lighting fixtures using LEDs, addressing the problems and concerns referred to above.
It is an object of the invention to provide an improved method for assembly of LED modules for use in lighting fixtures, such improved method overcoming some of the problems and shortcomings of the prior art, including those referred to above.
Another object of the invention is to provide an improved method for validation of an assembled module to satisfy necessary requirements.
How these and other objects are accomplished will become apparent from the following description and the drawings.
A method of assembly and validation of an LED module is disclosed. The method includes the steps of providing a base portion with a base inner surface and a cover with a cover inner surface which together define a module interior, the cover having at least one opening therethrough; putting a sealing member into the module interior, positioning into the cover opening a specific type of an LED lens designed for a desired distribution of the emitter light. The type of the LED lens is preferably verified. An LED emitter is placed into the module interior such that the emitter is aligned with the LED lens. The module interior is sealed by securing the base portion with respect to the cover thereby completing the LED module. In preferred embodiments, the base portion includes a heat sink for heat-dissipation from the LED emitter during operation.
The term “LED emitter,” as used herein, refers to an LED light source that may be in a form of an “LED package,”—a term known in the industry, or any other form providing LED-emitted light. Some examples of LED packages have one or multiple number of light-emitting diodes. Such multiple diodes may emit light with the same wave length which produce a common-color light. Alternatively, multiple diodes may emit light of different waive lengths thus of different colors which may be blended to achieve a desired-color light. Persons skilled in the art would appreciate a broad variety of available LED emitters. As is known, LED “packages,” with a single LED (or small LED cluster) may include a “primary lens.” Typically, the primary lens has an illumination pattern which is substantially rotationally symmetric around the emitter axis, and the primary lens itself is typically substantially hemispherical. When an LED lens, which is designed for a desired illumination, is positioned over an LED package with the primary lens, such LED lens is sometimes referred to as a “secondary” lens. It should be understood that the term “secondary lens” is used only for clarity of the current disclosure and in no way limiting this invention to the use of LED packages with primary lenses.
When the LED module is fully assembled, a power is provided to the LED emitter. An image of the powered LED module is then taken to test light-output characteristics. In preferred embodiments, the image of the LED module is utilized to test intensity, light distribution and color temperature of the LED emitter(s).
In preferred embodiments, the cover includes a plurality of openings. A specific type of the LED lens is placed into each opening. The aligning step includes a plurality of LED emitters on a mounting board, each emitter being aligned with its corresponding LED lens. A specific type of the LED lens is positioned into each of the openings.
The steps of positioning a specific type of the LED lens and verifying the type of such LED lens are preferably performed by a robot which incorporates a vision system. It is further preferred that the secondary LED lens includes a machine-identifiable lens-indicia. In such embodiments, the steps of verifying the type and orientation of the secondary LED lens are accomplished by the vision system reading the machine-identifiable lens-indicia.
In highly preferred embodiments, after the base portion has been installed over the cover, the method further includes the step of vacuum testing of the LED module for water/air-tight seal between the cover and the base portion.
In some preferred versions of the LED modules, the cover includes a plurality of screw holes. In assembly of such LED-module versions, prior to the step of vacuum testing, the method includes the steps of inserting a screw into all but one of the plurality of screw holes. The cover preferably also includes a power connection which may be in various forms such as an electrical connector or a wireway opening. When the power connection is in the form of the wireway opening, such wireway opening is sealed prior to the step of vacuum testing. The vacuum-testing step preferably utilizes the screw hole without a screw therein as an access point for the vacuum testing. It is highly preferred that the screws are inserted by using an automated screwdriver capable of controlling the torque utilized during the screw insertion for controlled pressure applied between the cover and the base portion.
In any of the described embodiments, it is preferred that the method further includes the step of providing a central database, whereby the central database provides assembly and testing parameters. It is also preferred that the method of the present invention is performed by an automated system receiving instructions from the central database for each particular step preformed by automated tool(s). The central database collects and stores data related to all or at least one of: the LED emitter and LED lens type, selection and orientation of the LED lens, screw torque, vacuum testing parameters, light output and color testing procedures.
It is further preferred that the LED module includes a unique machine-identifiable module-marking. Such machine-identifiable marking can be in any suitable form. Some examples of such marking may include a text, a set of symbols, a bar code or a combination of these marking types. The steps of the inventive method are preferably repeated multiple times to create a plurality of LED modules. The method preferably includes a further step of reading the unique machine-identifiable module-marking. The data of each unique machine-identifiable module-marking is associated with a specific individual LED module. Such date relates to that LED module's LED emitter(s), the type of the LED lens(s) such as selection and orientation of the LED lens(s), as well as light-output and color-testing procedures.
The term “base portion,” while it might be taken as indicating a lower position with respect to the direction of gravity, should not be limited to a meaning dictated by the direction of gravity.
The presently-described method applies to LED modules generally. However, the inventive method is particularly useful in the construction of LED modules described in U.S. patent application Ser. No. 11/743,961, filed on May 3, 2007, and Ser. No. 11/774,422, filed on Jul. 6, 2007, the contents of which are incorporated herein by reference.
LED lens 20 includes a lens portion (or “light-transmission portion”) 36 which is substantially transparent and a flange portion 38 which extends about lens portion 36. Lens portion 36 is adjacent to flange portion 38, as illustrated in
Thermal expansion of primary lenses 16 may cause in undesirable abutment of primary and secondary lenses. Resilient member 22 permits displacement of secondary lenses 20 while holding secondary lenses 20 in place over primary lenses 16.
As best seen in
Cover 26 has an inner surface 260 and base portion 18 has an inner surface 180. Inner surfaces 260 and 180 together define an interior 32. Cover 26 has openings 28 each aligned with a corresponding LED emitter 14. Cover 26 further includes screw holes 33 for use with screws 35 for securing base portion 18 with respect to cover 26. Cover 26 also includes a power connection which is shown as a wireway opening 37. As seen in
LED apparatus 10 further includes a metal layer 30, preferably of aluminum. Layer 30 is positioned into module interior 32 to cover electrical connections on mounting board 12 with LED emitters 14. Layer 30 includes a plurality of openings each aligned with corresponding lens 20 and permitting light passage of corresponding LED emitter 14 therethrough. The openings in layer 30 are sized to receive a corresponding primary lens 16 therethrough.
It should be appreciated that some versions of LED module 10 can include only one LED emitter 14 on mounting board 12, a corresponding lens 20 and a resilient member 22 against lens 20.
LED module 10 is assembled in a series of steps. In preferred example of the inventive method, cover 26 is placed such that its inner surface 260 is facing up. Shield member 24 is then positioned into interior 32 such that each shield projection is aligned with a corresponding cover opening 28. Then resilient member 22 is put into interior 32 with apertures 34 aligned with cover openings 28.
Various automated devices perform placing and verifying steps through testing or reading parts of LED module 10.
As schematically shown in
As seen in
Next, layer 30 and mounting board 12 are placed over the cover 26. LED emitters 14 on mounting board 12 are aligned with corresponding secondary lenses 20. Finally, the heat sink 18 is secured to cover 26 to close interior 32.
The step of screw installation 48 is then performed to seal interior 32 of LED module 10. It is preferred that a transducerized electronic screwdriver with parametric control be utilized. For example, a Chicago Pneumatic Techmotive SD25 Series electric screwdriver with CS2700 controller is capable of performing this step. Data related to the amount of torque to be utilized is received by the screwdriver from database 44. In screw-installation step 48, initially all the screws 35 but one are put into screw holes 33. Data related to the actual torque applied to secure screws 35 is then sent to database 44 for storage.
One remaining screw hole 33 is used for vacuum testing 50 of LED module 10 to ensure water/air-tight seal of interior 32. One example of a vacuum testing apparatus is a Uson Sprint IQ Multi-Function Leak & Flow Tester which can be utilized in vacuum-testing step 50. In step 50, wireway opening 37 is temporarily sealed and a vacuum is applied via the open screw hole 33. The vacuum is applied according to data from database 44. Actual vacuum-test results are sent back to database 44 for storage. After vacuum testing 50, final screw 35 is secured in same manner as described above.
The final step of the LED-module verification is a digital imaging 52 of LED module 10. For digital-imaging step 52, power is provided to LED module 10 to energize LED emitters 14. The imaging and analysis of LED module 10 are done through an automated system. One example of such system is a National Instruments Digital Vision Camera utilizing LabView Developer Suite software which can be utilized to complete digital-imaging step 52. A digital image of powered LED module 10 is taken. From this image the software can analyze light output, color characteristics, intensity and light distribution. Data related to these parameters are then sent to database 44 for storage.
Through the described inventive method, individual results can be tracked in a mass-production setting. In such mass-production setting, each individual LED module 10 can include a unique machine-identifiable module-marking 70 which is shown in
While the principles of this invention have been described in connection with specific embodiments, it should be understood clearly that these descriptions are made only by way of example and are not intended to limit the scope of the invention.
This application is based in part on U.S. Provisional Application Ser. No. 61/056,412, filed May 27, 2008, the contents of which are incorporated herein by reference.
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