Lights Form Factor Concepting

Owned by Adrian Au
Last updated: Jan 13, 2021
8 min read

Ownership

Form Factor DRI

Contributors

Project DRI

Form Factor DRI

Contributors

Project DRI

@Adrian Au

@Steven Poung

@Adrian Au

Research

 

Notes:

 

Notes:

 

Illuminated “light strips” from audi concept Q7

 

Tesla model X

 

Lightyear One

Tesla Model 3 Teardown

High-Level Lighting Layout Concept

Main Lighting CAD File:

GrabCAD\MSXIV\Development\Aerobody\Lights\MS-AER001 - For Lighting - REV 2.0.SLDPRT

(you can ignore MS-AER001 - For Lighting - REV 2.1.SLDPRT)

Slack Channel:

#mech-lighting

 

Design Considerations

Try to maximize the amount of design re-use between all the various lighting locations. This includes maintaining similar construction techniques, PCB designs, LED spacing/pitch, etc. in order to make our lives easier.

Terminology

In regards to PCB dimensions:

Dimension

 

Dimension

 

LED Pitch

  • Constant for all light elements

  • A spacing of ~8 mm between each LED should help to facilitate better diffusion/minimize LED “hotspots” (https://www.waveformlighting.com/led-strip-lights)

  • High Density LED strips use 120 LEDs per meter (8.3 mm pitch)

  • Medium Density use 72 LEDs per meter (13.9 mm pitch)

  • Low Density use 30 LEDs per meter (33.3 mm pitch)

PCB Length

  • Determined by desired light element length (number of LEDs), LED pitch, heat sync length requirements, and mounting hole locations

  • Constrained by amount of available space on either side of the light element

PCB Width

  • Determined by width requirements for heat sync and/or connector

  • Constrained by amount of available space above/below the light element

PCB Depth

  • Determined by depth requirements for heat sync and/or connector

  • Constrained by available space behind the light element

 

Form Factor Concepting

Headlights (DRL and Front Turn Signals)

The headlights consist of 3 individual lighting elements (with their own respective PCBs):

  1. Inner DRL (located closer to center of car)

  2. Outer DRL (located closer to outside of car)

  3. Front Turn Signal

Two DRL elements/PCBs are used as a result of having to fit to the curvature of the headlight while ensuring that the combined size of both DRL elements are large enough to be visible and aesthetically pleasing. It is proposed that the two DRL elements could be controlled individually for flashy sequential headlight start-up sequences.

The front turn signal element is located below the DRLs and is placed relatively inboard towards the center of the car. This location was determined in order to meet front turn signal visibility requirements.

 

Screenshots of Proposed Layout:

 

 

 

 

 

 

 

 

Dimension

Value

Notes

Dimension

Value

Notes

Light Element Size

  • Inner DRL:

    • 73mm x 8mm

  • Outer DRL:

    • 94mm x 8mm

  • Front Turn Signal:

    • 50mm x 6mm

    • Actual light diffuser will span entire length of headlight. However on the section in-front of the LEDs is expected to be illuminated. The goal is for a more hidden turn signal that is only visible when activated

  • Note that these measurements are with regard to the arc length of the element (which are heavily curved). Additionally, the light elements are also at a ~45 degree angle with respect the the PCBs

  • Thus, the projected length of the lighting elements when viewed from the front are much smaller

LED Pitch

  • 12mm (centre-to-centre)

  • Constant for all light boards

Number of LEDs

  • Inner DRL:

    • 4 White LEDs

  • Outer DRL:

    • 4 White LEDs

  • Front Turn Signal:

    • 4 Amber LEDs

 

Max PCB Size

(Length x Width x Depth)

  • Inner DRL:

    • 50mm* x 10mm x 50mm

  • Outer DRL:

    • 50mm x 10mm x 50mm

  • Front Turn Signal:

    • 50mm x 10mm** x 50mm

  • Max depth includes height of all components (i.e LEDs, heat sync)

  • *The distance between the edge of the outermost LED and the edge of the PCB should be less than 5.3mm to avoid blocking the light path of the Outer DRL

     

  • **The width of the front turn signal PCB should try to be within 10mm to avoid blocking the light path of the Inner DRL

 

  • All other dimensions are negotiable

 

Tail Lights (Rear Brake Lights and Rear Turn Signals)

Screenshots of Proposed Layout:

 

 

 

 

The LEDs for the rear turn signals and rear brake lights will live on the same PCB. This board will need to be as narrow as possible due to the tight space constraints above/below the board. Due to the space constraints as well as limited airflow, it is proposed that heat pipes will be used to transport heat towards the front of the car (where there is more space and better airflow for larger heat sinks/fins).

Dimension

Value

Notes

Dimension

Value

Notes

Light Element Size

  • 36mm x 4mm for Rear Turn Signal

  • 48mm x 4mm for Rear Brake Light

  • Can be made thicker (i.e 6mm vs 4mm) depending on how well light diffuses

LED Pitch

  • 12mm (centre-to-centre)

  • Constant for all light boards

  • Spacing between Turn Signal LEDs and Brake Light LEDs is 18mm (centre-to-centre)

Number of LEDs

  • 3 LEDs for Rear Turn Signal

  • 4 LEDs for Rear Brake Light

  • Please don’t hate me for using a different number of LEDs for the turn signals. It looked funny when both turn signals and brake lights were the same size

Max PCB Size

(Length x Width x Depth)

  • 100mm x 10mm** x 25mm

  • Max depth includes height of all components (i.e LEDs, heat sync)

  • **Board width should be as narrow as possible (something closer to 6mm would be appreciated)

  • **Using a 10mm board width, there is only 2-3mm of clearance between the outer surface of the aerobody and the board

  • All other dimensions negotiable

 

 

 

High Mounted Brake Light and BPS Fault Indicator

As per the ASC regulations, the high mounted brake light and BPS fault indicator will live in the same relative vicinity, sharing the same viewing angles (30° from center in both directions and 15° up from horizontal).

 

Screenshots of Proposed Layout:

 

 

The LEDs for the high mounted brake light and for the BPS fault indicator will live on the same PCB. The LEDs should be located as close as possible to the top edge of the board. This will allow us to maximize the viewable angle of the LED by placing it as close as possible to the outer surface of the car (prior to accounting for light diffusion material).

Dimension

Value

Notes

Dimension

Value

Notes

Light Element Size

  • 95mm x 13mm for Brake Light

  • 8mm x 8mm for BPS Fault Indicator

  • Don’t expect nor require entire specified area to be uniformly illuminated to regulation brightness

LED Pitch

  • 12mm (centre-to-centre)

  • Constant for all light boards

  • Spacing between Brake Light LEDs and BPS Fault LED is also 12mm (centre-to-centre)

Number of LEDs

  • 8 LEDs for Brake Light

  • 1 LED for BPS Fault Indicator

 

Max PCB Size

(Length x Width x Depth)

  • 150mm x 10mm x 25mm

  • Max depth includes height of all components (i.e LEDs, heat sync)

  • LEDs should be located as close as possible to top edge of board

  • All dimensions negotiable

 

 

 

Side Mark Turn Indicators

 

Screenshots of Proposed Layout:

 

 

 

 

Dimension

Value

Notes

Dimension

Value

Notes

Light Element Size

  • 83mm x 20mm

  • Don’t expect nor require entire specified area to be uniformly illuminated to regulation brightness

LED Pitch

  • 12mm (centre-to-centre)

  • Constant for all light boards

Number of LEDs

  • 4 LEDs

 

Max PCB Size

(Length x Width x Depth)

  • 50mm** x 10mm x 25mm

  • Max depth includes height of all components (i.e LEDs, heat sync)

  • All dimensions negotiable

  • ** Board length should be as short as possible to minimize housing size for aesthetic purposes

References

Electrical Page: MSXIV High Mounted Brake Light

Array Layout Page: Final Array Layout

File links or locations

Design Journal

Date (YYYY-MM-DD)

Notes

Date (YYYY-MM-DD)

Notes

2020-05-25

Layed-out initial CAD model architecture:

  • Headlight Lens to be thermoformed polycarbonate and will be glued and fit to aerobody flanges (side panel, hood, panel, bottom panel)

  • Headlight Housing to be 3D printed in sections (relatively large part) and will be fastened or glued to interior of aerobody

  •  

2020-06-05

Took screenshots of CAD and added to confluence. Came to conclusion that headlight has the potential to be really big (see poorly dimensioned “drawing”). Will need to determine what maximum feasible size of lighting elements are for DRL and front turn signal

2020-06-06

  • #LightingTaskforce meeting liked the “non-bulby” look.

  • A common theme between “boring” headlights: looks too bulby. lol.

  • Follow-up to investigate feasibility.

 

2020-07-03

Added tail lights section

2020-09-04

Updated headlights section (finally)