“Dynamic floor projection technology, capable of displaying any pattern within the same module, reshapes consumer perceptions of exterior lighting by offering new and innovative lighting capabilities. Innovative lighting features include a car light “carpet” that illuminates the surrounding area outside the car or projects vehicle information from the side mirrors such as EV battery level and remaining range, tire pressure warning, traffic warning, turn indicators, check engine light warning , gasoline volume/mileage, etc. Floor lighting also has other enhancements that help the car communicate with drivers and pedestrians, including corner lighting, reversing lighting, vehicle customization and parking indicators.
“
Introduction
Dynamic floor projection technology, capable of displaying any pattern within the same module, reshapes consumer perceptions of exterior lighting by offering new and innovative lighting capabilities. Innovative lighting features include a car light “carpet” that illuminates the surrounding area outside the car or projects vehicle information from the side mirrors such as EV battery level and remaining range, tire pressure warning, traffic warning, turn indicators, check engine light warning , gasoline volume/mileage, etc. Floor lighting also has other enhancements that help the car communicate with drivers and pedestrians, including corner lighting, reversing lighting, vehicle customization and parking indicators.
The dynamic ground lighting system supports high-resolution projection for clearer communication and safer driving. These systems also need to be compact and small enough (approximately 50mm in length, 25mm in width and height) so that they can be installed in doors, side mirrors, headlamps, tail lamps or embedded in front and rear bumpers. DLP® technology projects dynamic content on the ground or other surfaces around the vehicle and offers many advantages: Not only does it enable vehicle-pedestrian communication, but it can also convey more complex driver information to surrounding vehicles in a more intuitive way.
A Brief History of Automotive Lighting
In recent decades, many changes have taken place in automotive lighting systems, among which the lighting technology used in rear, side and front lighting has changed a lot. Automotive headlight sources have evolved from tungsten halogen lamps to high-intensity discharge bulbs to high-power white LEDs, achieving higher luminous flux and efficiency and extending operating life.
Many headlamps utilize an integrated light source configuration that includes a reflective lens and lens system to provide high beam, low beam and fog light functions. A similar layout combined with rear lights and rear fog lights provides a variety of signaling functions. Other on-board lighting includes side mirror lighting for redundant turn signals, night lighting, and a central high-mounted stop light (CHMSL). Auxiliary vehicle lighting includes other custom features such as automaker logo lighting and even projected logo lights located inside the doors.
Automotive lighting systems must comply with NHTSA or ECE regulations for standardized signaling and reflective devices. Safety requirements for headlamps are also becoming more stringent, with mandatory light shape regulations and precise photometric requirements. Designers must comply with these requirements, while also meeting the manufacturer’s practical and decorative requirements for the shape of the vehicle. DLP technology not only easily meets these requirements by complementing any light source with a digital micromirror device (DMD), a programmable MEMS reflector array, but also further enhances the overall functionality of the beam.
DLP Technology Overview
DLP technology can Display dynamic content by using DMD. DMDs contain up to 8.3 million micromirrors that can be switched between two positions to redirect incoming light based on electrical input (Figure 1). The technology also requires subsequent image processing, memory, light sources and projection optics to control the system and display dynamic content.
Figure 1. DLP technology displays high-resolution images by controlling millions of micromirrors at high speed.
DMD reproduces patterns by individually switching the micromirrors that make up the pixels of the projected content. The following introduces the important role of DLP technology on automotive lighting systems from five aspects.
・ Repeatable programmability
DLP technology dynamically changes content without modifying any optics attached. The benefits of this feature are even more pronounced when compared to common static projection techniques such as the “gobo” (also known as Gobo) commonly used in stage lighting applications. The Gobo projector generates the image using a woodcut filter similar to a stencil to create a pattern of projected light. This type of projection technology has been used in custom road lighting, but the DLP® Dynamic Ground Projection Technology image for exterior lighting in cars is not modifiable, so a completely separate module must be included to generate a static image.
DLP technology is fully programmable, enabling the projection of multiple images at different times. For example, door opening warning signs can be projected on demand, or other complex images can be updated based on user needs and road conditions, while implementing custom lighting in the side mirror light sockets. For example, when a door is opened or the driver places his hand on the door handle, a warning sign will be projected to remind the door that the door is about to open. This can be helpful for cars parked near bike lanes.
・ Full color gamut support
Static projection techniques are generally limited to displaying images in a single color. For example, Gobo utilizes dichroic templates for color image projection, but dichroic filters can only produce a single color.
DLP technology rapidly transmits red, green and blue LED pulses or laser pulses to the DMD for full color support. DMD’s switching speed is a few microseconds, so a single imager can be used for the above three colors to produce stunning images and videos.
・ Not bound by light source
Since DLP technology is a reflection-based technology, any type of light source can be used, including LEDs and laser diodes, which will replace incandescent or gas discharge light sources for front and rear lighting. With this flexibility, DLP technology can accommodate multiple lighting technologies in a wide range of wavelengths, including visible and near-infrared light, in automotive lighting and communication systems.
・ Has met automotive-grade requirements
Automotive-grade DMDs, DMD controllers, and power management ICs now operate over the C40°C to 105°C operating temperature range and pass the necessary ESD certification for automotive ICs, making them ideal for use in current automotive lighting systems DLP technology provides support.
・ Small size
The main goal of automotive lighting systems is to enhance the aesthetic presentation of the car. In addition to the overall shape and materials of the car, the lighting system is a key element in creating a car’s refined appearance. Designing the shape of an automotive light involves a lot of work, and often, tighter tolerances in the internal circuitry. The entire DLP subsystem can easily fit into a slot in the side mirror or other tight areas around the car.
DLP Technology Use Cases
Given these advantages, DLP technology has a bright future in automotive lighting applications. Below are some possible applications of DLP technology and automotive lighting systems.
・ Car exterior lights
DLP technology can greatly expand the functionality of automotive small exterior lights, including inside doors, foot pedals or at the bottom of side mirrors. DLP technology generates dynamic images without the need for other moving components. As a result, when the driver is approaching the vehicle, the small exterior lights can be used to project low tire pressure or door open warnings from the side mirrors, or to project vehicle logos or other styles of images and videos from the bottom of the small doors. These capabilities allow OEMs to fully customize their messaging and branding through small exterior lights, rather than the static logos generated by today’s lights. The lights can only display a single pattern and cannot be used to communicate with pedestrians or drivers.
Figure 2. Small exterior lights projecting a logo onto the ground from the side mirrors.
・ Car light blanket
Side-view mirror lights perform multiple functions simultaneously, serving as a standard turn signal as well as projecting a light carpet spanning the entire length of the vehicle in the side area of the vehicle (Figure 3). This type of lighting is especially useful when the driver is leaving or approaching the vehicle in dimly lit areas or at night.
Figure 3. Automotive light carpet projected from multiple locations on the vehicle.
・Warning the driver and passengers
DLP technology provides a means of warning that is more advanced than the flashing lights and gestures drivers currently use to warn others. Warnings generated using DLP technology can take the form of visual information displayed on the road surface, indicating information such as hazardous road conditions or special traffic areas such as construction sites or school areas. Drivers can also project on the crosswalk, or choose to display a preset message on the ground that says “Crossing is safe” to communicate directly with pedestrians trying to cross the street.
・ Broadcast intent: private car
The Broadcast Intent feature avoids many accidents caused by nervousness, hesitation or confusion of not knowing where other drivers are moving. DLP projections convey simple intentions that are notoriously difficult to articulate, such as U-turns or K-turns. Taxis can use symbol projections to warn oncoming traffic that a vehicle is about to come to a complete stop, and can project onto the ground to alert passengers that passengers are about to get off. A vehicle that is about to exit its lane and has a blind spot can project its exit intent. Autonomous features such as parallel parking or reversing can project their path backwards, indicating their final parking location, thereby clearly communicating their intent to passing vehicles and cyclists (Figure 4).
Figure 4. The driver can broadcast his expected trajectory by projecting the driving route on the ground behind the car through the rear lights.
・ Broadcast intent: Public car
A fire truck, ambulance or police car can publish its exact route, giving drivers of nearby vehicles a better idea of where to drive to give way. The police car can communicate the intention that the driver in front needs to pull over to the side of the road or change lanes in order to overtake. Large vehicles that require a large turning radius, such as buses and tractor-trailers, may need to communicate to drivers behind the need to back up in order to make a successful turn. Buses can project their routes into and out of bus stops so drivers of nearby vehicles can better understand their movements. A tractor-trailer carrying oversized cargo can project the exact amount of space that other vehicles should give up when passing through tight spaces. School buses can also project their intent to keep passengers safe. For example, school buses could project stop signs on all lanes instead of using standard stop signs.
・ Route guidance
The DLP subsystem can aid navigation by augmenting the driver’s field of view with graphics, such as showing lane lines that do not exist. The idea could be based on real-time visual guidance, helping the driver while announcing the driver’s next direction to nearby vehicles.
in conclusion
Dynamic ground projection is the future development direction of automotive lighting systems, and it is also the development trend of adaptive high beam technology. The ability to individually control the millions of pixels in a projection system enables a variety of vehicle applications. Compared to other static projection technologies such as Gobo, DLP technology offers greater flexibility and a small, reprogrammable multicolor platform with high resolution. In addition, DLP technology leads the way among many dynamic digital projection technologies due to its relative cost-effectiveness, flexibility to accommodate different light sources, and overall efficiency. Given that DLP chipsets are already automotive-qualified and have custom processing capabilities specific to automotive applications, their time-to-market may be shortened. The automotive lighting industry has the potential to benefit greatly by taking advantage of these technological leaps and implementing spatial light modulators such as DMDs for agile beam illumination and message/symbol projection.
The Links: LM201W01-SLA1 G215HAN010
