What does it take to achieve good IMSE illumination? Knowing material properties and teamwork.

Creating good illumination for an IMSE product is a multistage process. The design process consists of gathering illumination performance requirements, selecting a light source, the simulation process and co-operation spanning the IMSE engineering team. The design begins by achieving shared understanding of illumination requirements for a specific use case with the customer. With these requirements, light sources with sufficient performance can be selected for the design. This blog post concentrates on the simulation process and co-operation across the IMSE engineering team, and how essential these two process steps are for achieving high quality illumination.

A high-quality illumination example

What does high quality illumination mean in practice? We can think of examples from the automotive industry. For example, illumination in a car control panel needs to be informative and intuitive. The driver of a car must be able to quickly and easily operate control functions and understand vehicle status information guided by illumination. The illumination must also be of high quality so that its use is comfortable: bright enough to see easily, but not so bright that it dazzles or distracts the driver.

Simulation is the fast track to high quality illumination

With optical simulation software you can create predictable and high-quality illumination and test different design setups virtually. There are numerous optical simulation software packages that can predict the appearance of the an illumination implementation. However, even the most powerful design tool is useless if it does not have the information on the properties of the materials used in the IMSE product. This is essential because IMSE parts combine multiple materials that influence lighting performance, typically in-mold labeling film, graphic inks, conductive inks, and transmit light through injection molding plastics such as polycarbonate or TPU.

As an illumination engineer you have to define how each surface reflects light when a light ray meets the surface. The reflection may be specular, where the surface is acting as a mirror; or it may be diffuse, where the light is well reflected, and scattered in many angles. The reflection coefficient may be high, where most of the light energy is reflected back, or low, as when the light energy is absorbed to the surface. Similar concepts apply to transmittance: light may pass through the material minimal impact to magnitude or direction or it can modify the light dramatically, even change its color.

All the materials used in an IMSE product must be optically modeled for the illumination simulation software so that you, as an illumination engineer, can predict the end result as well as possible. This will reduce the iteration rounds within the design team and in production.

IMSE design requires teamwork

Designing an IMSE part is a multidisciplinary process—a perfect illumination model alone is not enough. There are interactions between illumination, mechanics, electronics and tooling design, to name some primary relationships. There are a number of talented professionals waiting for your results in order to do their work. You have defined the locations for each LED in your design, and those LEDs need to be placed on the electronics layout for circuit routing. To get that work started, you send the LED layout file to the hardware designer. And, with the mechanics designer, you may have modified the 3D mechanics for better optics. Finally, you define the ink recipe for film designers, so that they can finalize the graphics information for production. Each of the engineering disciplines must work collaboratively to achieve overall design and performance objectives. The mechanical model, for example, is needed before starting the illumination design.

As you can see from the above description, IMSE product design as a whole is a multistage and multidisciplinary process. There is a lot of information that needs to be shared between disciplines in order to have an efficient design process. The key issue in delivering information within a team is fluent and frequent communication, and that takes a shared commitment from the entire team, including learning how to effectively communicate across engineering disciplines and being open minded. One colleague might understand your message from a half of a word, and for another, a few informative drawings deliver the information. Communication behavior is always reflected back between the team members. In the TactoTek engineering team, the cooperation between different disciplines is fun, fruitful and often very innovative.

About the writer

Pasi Korhonen, Principal Engineer, Illumination

Pasi works as an Illumination Principal Engineer in TactoTek, working on new illumination solutions for IMSE with our Advanced Engineering team as well as in NRE projects with customers. Pasi has 20 years of experience in consumer electronics, designing acoustics and illumination solutions for various applications. Pasi holds an M.Sc in Electronic Engineering. In his free time, Pasi coaches floorball juniors, enjoys outdoor activities on skis or on his bicycle and forestring.