Controlling Color Variation in White LEDs

The light emitted from LEDs can vary significantly across the white color spectrum. Colors ranging from “warm” white (yellowish hue) to “cool” white (bluish hue) occur with many variations in between. These ranges are each assigned Correlated Color Temperatures (CCT), measured in Degrees Kelvin. An LED array with different color temperatures mixed together may have profound ef­fects on the quality of the end product. Customers in the LED lighting industry are very critical of such color variations in their products, and this is where the challenge for attaining more uniform color output arises.

LED Manufacturers and Binning 

LED manufacturers control white color variations through the process of “binning”. Binning is the method of sorting and grouping LEDs according to specified parameters, satisfying applications that require tighter color tolerances and less variation between LEDs. For example, one kind of LED will have numerous bin codes that define a more precise color temperature within that LED “family”.

However, the precise outcome of color binning can be lost if companies purchasing from the LED manufacturers fail to keep track or handle the binned LEDs properly. Bin control remains crucial as the LEDs travel up the supply chain to LED solution providers or lighting manufacturers.

Norlux Solution 

At Norlux, the key to building LED arrays with similarly binned LEDs is lot binning control and traceability. Tracking the origin of raw material, especially LEDs, is important to a manufacturer like Norlux. Our team assigns internal part numbers along with a manufacturer’s LED part number in order to differenti­ate the number of LED variants we handle. Every time a new shipment of this particular LED arrives at Norlux, the receiving department will assign a specific internal lot number for that LED. All the LED information is stored under this specific internal lot number. By doing so, Norlux has the ability to trace back all the necessary information related to that LED lot.

Additionally, Norlux also has the capability to measure CCT and chromaticity values with integrating spheres and colorimeters. Data captured from measuring the LEDs’ output can be compared to the LED shipping data provided by the manufacturer and verified for synergy.

Benefits 

By assigning an internal part number and a specific batch number, Norlux is able to manage its white LEDs better when “kitting” the parts for assembly. The possible problem of having LEDs with different part numbers within one product is eliminated because only the specific part number shows in the bill of materials of the prod­uct. In addition, the possibility of releasing the LED with different bin codes is eliminated because each specific internal lot code assigned has the corresponding LED bin code information with the lot code.

If the customer requests a product to be built with a specific bin code, our production planners are able to trace back the bin codes through the internal lot code assigned. Norlux can even mix different internal lot codes as long as the bin codes assigned are the same (even with different manufacturer lot), thus maximizing optimal LED usage.

Conclusion 

By having appropriate control and traceability of white LED products, managing LED bin codes becomes second nature. Having this system in place eliminates the possibility of placing different shades of white LEDs in an array or assembly. This leads to reliable color consistency and ultimately great products that our customers appreciate and rely upon. For more information, please contact Norlux at 630-784-7500 or visit us at www.norluxcorp.com.

3D Renderings Make Product Design Complete

Successful engineering companies take advantage of two important assets: utilization of computer-aided de­sign (CAD) technology, and employment of skilled designers who know how to make the most of available CAD tools. CAD technology has become the cornerstone of today’s successful product development, as it elevates productivity and introduces innovation to the process. However, as with any tool, maximizing the potential benefits of the CAD system demands a combination of planning, organization, and expertise. Using the right tools can make the difference between success and failure.

Product development continually evolves, as do CAD tools. Competition demands improvements in productiv­ity and advances in innovation. With many variables and goals constantly changing, designers and engineers are required to be knowledgeable with CAD tools and be capable of using more than one CAD tool to design efficiently for the best result.

It is said that “a picture is worth a thousand words” and such is the case with design schematics. The capability to visualize the design during the engineering process produces fewer errors and quickens time-to-market. By incorporating a combination of CAD tools during engineering, the designer becomes familiar with the constraints involved and is capable of considering the overall picture and competent to design with fewer mistakes.

The Design

Designing a high-density integrated electronics package for an aircraft application creates numerous challenges. The project had to fit a specific location with size constraints of 1 ½ inches square and with depth confine­ments of 2 ½ inches. The project housing was designed in 3D to define the interior space available for printed circuit boards (PCBs), wires, sensors and buttons. The design was exported from the 3D software and imported into the PCB design software. This provided a valid PCB outline to begin the electrical design work.

The unique aspects of this design were the use of multiple boards and mediums, two rigid boards and one flex board. Two boards in this appli­cation were a 3D puzzle that had to mesh together. Although irregularly shaped, the outlines provided a valuable design space for layout of the circuits. Additional keepouts were added for holes, stand-offs, and header placement. The net list was im­ported and a variety of components displayed for layout. The components each had custom attributes that defined the geometric height, which be­came imperative during the import back into the 3D tool.

The components were divided in power components and logic components. Power components were placed on one board, logic on the other. The power components were located per best layout practices to generate the optimum layout. This design was then exported, and then imported into the 3D tool to generate the area available for safe component placement on the logic board. Once defined, the design was exported and imported back into the PCB design tool.

Using this information, the logic board was generated to create the best possible outcome. Component layout was not as critical for logic components and longer circuits may have been generated since this was not high speed. Again, the design was exported and then imported into the 3D tool. The two designs were coupled and a verification of clear­ances was confirmed. If errors were located, the design was reverted back to the layout tool for correction. The process was continued until no errors were found, typically 2 – 3 iterations.

The Visibility

By maximizing the use of multiple CAD tools, the clearance issues are verified before a costly process of ordering, manufacturing and assembly is incurred. Costs are compounded as the engineering process progresses. By resolving any interference issues sooner, the overall expense is greatly reduced.

Using a 3D component library, realistic looking components are integrated into the PCBs and incorporated into the final 3D assembly. This creates a pleasing image the customer can appreciate. The customer now has the availability to see the final product long before any prototypes are run. The customer can then decide if any further changes are required before progressing to prototypes.

Not all companies make the most of 2D to 3D electrical design. Norlux utilizes multiple CAD tools to create valuable products for its customers. For more information or to inquire about Norlux’s engineering capabilities, please contact Norlux at 630-784-7500 or visit us at www.norluxcorp.com

Managing LED-Based Projects: Importance of Time to Market

The life cycle for LED products is relatively short due to the continued rapid advancement of LED technology. After a state-of-the-art product is launched, it may only have a couple years before it is overshadowed by new competitive developments. Time to market is important for most companies, but for those launching LED-based products, timing is absolutely critical.

When examining a typical LED project, measurements such as light output, effi­cacy, and size requirements are now seen as moving targets. This short product life cycle makes it that much more critical to get a product to market as quickly as possible. Clearly, the longer it takes to launch a new platform, the less time one will have to recoup development costs and turn profits. Time is money!

As project teams race through the Scope, Design, Prototype, Validation and Production stages, there are many opportunities for the baton to be dropped, that’s where pro-active project management comes in. A Project Manager can mitigate time delays especially as team members fail to realize the project was ready for them.  Each delay of this nature can be measured in hours and sometimes days; the end result can add up to weeks for any given project.

The Norlux Solution

At Norlux, the key to avoiding communication delays is to automate project management processes. One must create a project template (like Microsoft Project) preferably through an existing company database. This template would be linked to other aspects of the database to access information like part numbers and team members’ e-mail addresses. Using macros and auto-generated e-mails, individuals will automatically be sent an e-mail notification when they can begin their task. Of course, team members can always access the project within the database to view the status. Following is a step-by-step process highlighting the details:

1. Project Manager creates timeline, complete with itemized tasks and due dates. As typically done with Microsoft Project, the Project Manager would identify which tasks can be done in parallel and which are dependent on predecessors.
   
2. Project Manager enters each task into the project template within the database using pull-down menus for common tasks and team members’ names.
   
3. Project Manager enters predecessors for tasks (i.e. electrical schematic must be completed before PCB layout can begin).
   
4. Project Manager has standard kick-off meeting with all team members to walk through the project requirements, action items and timeline.
   
5. Database shows each team member his/her personal list of open action items within a pop-up window each time they log into the database.
   
6. Team members simply click the “complete” box next to their action item when done. The database automatically fills in the completion date.
   
7. Database automatically sends an e-mail notification to the next team member(s) downstream showing they can now start on their action item.

When there are multiple predecessors, the auto-email notification is only sent out after ALL corresponding proceeding tasks are completed. Also, the auto-emails are sent only to those team members waiting on that specific task completion.  A critical component to the success of this automation scheme is to avoid sending unneeded notifications and reminders, otherwise team members may learn to ignore the messages. Keep all communication clear, timely and concise.

Smooth transitions are key to finishing projects quickly, and communication is key to smooth transitions. It takes a bit more time up front to set-up an automated project schedule. However, once it is put into motion, communication becomes effortless and instantaneous. By carving the dead time out of the project process, one can dramatically improve speed to market and enjoy all the corresponding financial benefits.

Contact Norlux today and take advantage of our accelerated product development process. We are the North American leader in the design and manufacture of custom LED lighting solutions.

Safety Is A Norlux Top Priority

Norlux utilizes several "best-practices" to ensure the safest possible working environment. These include the Gemba Walk, Residual Risk Reduction, and Behavioral Based Safety. These help the company to protect both employees and visitors.

A “Gemba Walk” on the factory floor has become daily practice for Norlux management. Gemba is the Japanese term for "the real place." Each morning, the Walk is focused on a different operating principle, such as standardized work, 5S, Green wastes, manufacturing wastes and safety.  If a hazardous situation is observed, action is immediately taken to fix it. Controls are put in place and additional operator training is conducted if necessary.  If the hazard requires more attention, an action is logged to ensure adequate follow up.

The Residual Risk Reduction (R3) proactive approach helps Norlux to eliminate unsafe conditions by constantly examining processes and executing ways to reduce risk before any accident occurs.

The Behavioral Based Safety (BBS) program helps ensure that each operator is performing his or her job in a safest manner possible. Monthly safety training sessions include both front-office and production employees. Case studies featuring hazardous situations are presented as a learning tool, complete with warning signs and appropriate immediate and future corrective actions. Education sessions cover issues from proper lifting technique for heavy items to proper handling of hazardous materials.

Norlux employees are empowered to speak up about safety issues and prevent accidents. The manufacturing floor is clean, with good visual safety indicators throughout the facility. Norlux is an ISO 9000-2008 certified LED systems integrator.