Boyd was supplied with the PRNDL and an LED light fixture that was identical to the actual model used in the vehicle. The customer also provided target values for brightness and color for each character on the gear shift indicator.
Work began in Boyd’s state-of-the-art light lab. First, Boyd’s engineers used a spectroradiometer to get a reading on all five individual LEDs in the light fixture. This provided a luminance value in footlamberts, which became a reference point while creating the diffuser. To ensure uniformity across the iconography on the PRNDL, multiple spectroradiometer readings were taken across each character and subsequently averaged together. Various lighting scenarios were then tested in the lab to ensure the diffused backlighting accurately matched the desired look, regardless of external lighting conditions.
With these reference luminance values, it was possible to begin mixing colors for screen-printing the inks on the diffuser. The colors were mixed based on the spectroradiometer readings and the X/Y stimulus values provided by the customer. Each ink had to closely match the specified reference color, so several inks were created for different areas of the diffuser. The inks were screen printed on the polycarbonate sheet in three separate passes. On the fourth pass, an adhesive was printed onto the back of the diffuser for its easy adhesion to the PRNDL.
The PRNDL printing project also needed to reconcile the specified values with the actual look of the part. Based on several variables such as external lighting and different spectroradiometer readings, colors can match specifications but still look off on the PRNDL itself. To prevent this, densitometers and spectroradiometers were used to frequently spot-check different parts throughout production runs to ensure they met the correct values.
With five bright LEDs installed within the compact lighting fixture, it was also crucial that the PRNDL didn’t have hot spots or emanate light from undesired areas. The ink densities were monitored and adjusted throughout production to prevent bright spots and excessive light escaping through the edges of the PRNDL.