Developing Automotive Display and Lighting Testing

Dashboard of the 1925 Packard Touring. Photo Credit: Creative Commons (CC BY-SA 3.0 US)

Dashboard of the 1925 Packard Touring. Photo Credits: Creative Commons (CC BY-SA 3.0 US)

Early Model-T Ford vehicles did not possess a speedometer (their top speed was only 35 mph). However, not long after, dashboards started to include numerous gauges, indicators, and vehicle controls.

The earliest automobile headlamps were introduced towards the end of the 1880s and were powered by oil or acetylene. Electric-powered headlamps originally entered the market in 1898, although the earliest integrated ignition and electrical lighting system was not developed until 1912, by General Motors.

1965 AMC Rambler Classic with sealed headlamps (in use from 1940-1984, before the advent of composite headlamp assemblies with replaceable bulbs). Photo Credit: Christopher Ziemnowicz

1965 AMC Rambler Classic with sealed headlamps (in use from 1940-1984, before the advent of composite headlamp assemblies with replaceable bulbs). Photo Credits: Christopher Ziemnowicz

Modern Automotive Lighting & Displays

Since their earlier advent, automotive lighting and displays have progressed substantially, and are now crucial to the functionality, safety, and driving experience of all vehicles.

Designers and manufacturers continue to advance new technologies, with contemporary and future vehicles likely to integrate innovative new components, including adaptive LED headlights, transparent head-up displays (HUDs) projected onto the windshield in the driver’s line of sight, and integrated camera systems to provide drivers with a more comprehensive view of areas around the vehicle.

A range of dashboard instrumentation panels and displays found in today’s modern automobile.

A range of dashboard instrumentation panels and displays found in today’s modern automobile.

Quality Assurance for the Cars of Today & Tomorrow

In response to technological developments, auto manufacturers are required to satisfy ever-changing regulations and industry standards for the safety and performance of essentially all elements within a vehicle. To assist designers and OEMs with R&D and production quality of critical vehicle systems, Radiant Vision Systems offers a comprehensive portfolio of light & color measurement solutions that enables auto manufacturers to test and measure virtually all self-illuminating elements inside and outside the vehicle.

For a closer look at all the ways we’re helping OEMs ensure the quality, safety, and performance of vehicles, watch Radiant’s automotive solutions video:

In-Vehicle Displays

Embedded console, c-stack, and dashboard display screens are increasingly common in-vehicle instrumentation, navigation, and entertainment. These displays need to be capable of performing under a broad array of ambient light conditions (from nighttime to bright sunlight).

Automated visual inspection using Radiant ProMetric® Imaging Colorimeters and TrueTest™ software enables the detection of quality problems during the design or production process, permitting manufacturers to determine potential process enhancements, increase yield, and obstruct flawed products from reaching consumers.

Utilizing an in-built library of tests for anti-glare “sparkle” effects, chromaticity, contrast, image sticking, luminance, mura, pixel defects and uniformity, TrueTest can be efficiently calibrated to satisfy particular criteria, or to test against standard visual performance parameters, like the German Automotive Black Mura Standard.

Display View Angle Performance. View angle measurements are essential to automotive displays, particularly as these are typically viewed off-axis from the driver or passenger point-of-view. Radiant’s FPD (flat-panel display) Conoscope Lens offers an angular resolution of 0.05 degrees per CCD pixel for high-accuracy quantification of angular contrast, CID chromaticity coordinates, correlated color temperature (CCT), luminance and radiance. Utilizing Fourier optics, the lens records every view angle up to ±70 degrees in a single image for analysis.

Radiant’s FPD Conoscope Lens mounts directly to a ProMetric Imaging Photometer or Colorimeter (either 16- or 29-megapixel CCD options)

Radiant’s FPD Conoscope Lens mounts directly to a ProMetric Imaging Photometer or Colorimeter (either 16- or 29-megapixel CCD options)

A Radiant view angle measurement solution integrates the FPD Conoscope Lens accessory and a ProMetric imager. When combined, these technologies lower complexity, cost and form factor, particularly in comparison with other goniometric measurement systems for angular measurement R&D applications. As a consequence of its size and measurement efficiency, the FPD Conoscope Lens solution also allows in-line inspection of display view angle in production settings.

Measuring Sparkle of Anti-Glare Displays. The majority of in-vehicle displays are visually affected by applied anti-glare coatings and films. Because automobile displays need to be viewed in all types of ambient lighting conditions, anti-glare treatments assist in the reduction of reflective glare from sunlight or street lights. Nevertheless, such anti-glare treatments can also generate their interference, known as “sparkle”—a grainy appearance— which can affect a display’s perceived quality. The measurement of perceived sparkle makes sure that the user experience sets the bar for the manufacture of AG displays.

In accordance with extensive research conducted with leading OEMs, Radiant has conceptualized a standard sparkle measurement methodology as a means of obtaining quantifiable data that consistently correlates with human visual perception of display quality. The Radiant Sparkle Measurement Method is the first to permit OEMs to set a numeric tolerance (for example, maximum 2% measured sparkle) for displays provided by their vendors, guaranteeing a consistent standard of quality across all displays, irrespective of product, supplier, or time and location of testing.

Headlamps & Exterior Lighting

Contemporary smart headlamps necessitate an array of measurements to guarantee adequate illumination at all settings. To speed up this process, Radiant ProMetric imagers capture a broad spatial distribution of headlamp patterns on walls or screens, yielding accurate quantification of the light source’s illuminance distribution in a singular measurement. Following quantification, it is possible to analyze a light assembly for multiple criteria, utilizing the PM-HL™ Headlamp Evaluation Module. PM-HL offers evaluation of common ECE and US regulated test points, conversion to roadway illumination distribution, and more.

False color used to analyze the roadway distribution of a headlamp in the PM-HL software module.

False color used to analyze the roadway distribution of a headlamp in the PM-HL software module.

Lighting Assemblies. An alternative methodology for determining an illumination distribution—perfect for new LED-based luminaires—is to quantify a source’s near-field distribution. The luminaire is placed on a goniometer (such as the Radiant PM-NFMS™) while an imaging colorimeter, guided by automated measurement control and analysis software, quantifies luminance or lit-appearance at each view angle. The far-field luminous intensity distribution is calculated using the software. The illuminance distribution can subsequently be computed for all arbitrary distances.

Radiant

Radiant's PM-NFMS offers a rapid, compact solution for far-field beam pattern quantification (left). A light source is placed on a two-axis goniometer and rotated, while a stationary imaging colorimeter mounted in the near-field quantifies color, luminance and (optionally) spectrum at all angles. Software can subsequently compute the far-field luminous intensity distribution at all distances, in accordance with the near-field data. To the right, the extrapolated luminous intensity distribution of an automobile headlamp at 3.4 m, as acquired from the near-field goniometer measurement, is displayed.

Small Light Sources. Small light sources, including single LEDs, can be characterized by a near-field model for usage in optical design applications. To generate this model, a precision goniometric system (SIG-400 Source Imaging Goniometer®) with a ProMetric Imaging Colorimeter performs measurements of color and luminance of the light source from more than one viewing angle.

The measurement output is a Radiant Source Model™ (RSM) file, which delineates the near-field luminance distribution around the source. This RSM is supported by every major optical/illumination design software package and undergoes conversion to a ray set utilizing Radiant ProSource® Software. These ray sets support the optical design and permit the user to extrapolate a near-field model into a far-field model.

LED Lighting. Quality control for LED headlamps, taillights, and decorative light strips can be easily tackled using a ProMetric Imaging Colorimeter and Radiant software. It is possible to determine luminous intensity distribution, quantify uniformity of luminance and color along a path (such as an LED pipe), and identify failed LEDs in a cluster. ProMetric and TrueTest software event permits the drawing of ROI (regions of interest) on a measurement image as a means of evaluating lighting components of any size or shape.

Automotive headlamp assembly with LED light strip.

Automotive headlamp assembly with LED light strip.

Measuring light strips

Measuring light strips and LED pipes for luminance, chromaticity, uniformity, yellowing and color change (top), and for intensity, D intensity, chromaticity, and D chromaticity (bottom) in TrueTest software.

Measuring light strips and LED pipes for luminance, chromaticity, uniformity, yellowing and color change (top), and for intensity, D intensity, chromaticity, and D chromaticity (bottom) in TrueTest software.

Head-Up Displays (HUDs)

HUDs represent unique measurement hurdles for manufacturers. ProMetric Imaging Photometers and Colorimeters feature an electronically controlled lens that is particularly effectual at identifying and focusing on an image projected into infinity.

The TT-HUD™ module of Radiant’s TrueTest analysis software offers precise chromaticity and luminance measurements at all working distances and can test in daytime, normal and nighttime settings to guarantee consistent visibility of digital projections in ambient settings. It is possible to integrate high-resolution ProMetric cameras and software with HUD systems to allow fully automated testing, with API to regulate test images and analyses in sequence from contrast, warping, ghosting, MTF, and more tests.

Interior Lighting and Instrumentation

Instrument Clusters, Controls, Tell-Tales & Indicators. A ProMetric Imaging Colorimeter with ProMetric Software offers a straightforward and precise approach to testing illuminated characters. The software encompasses a powerful tool (Auto-POI, or Automatic Points-of-Interest), which enables operators to automatically choose points of interest based on color and luminance values (Lv and CIE x,y thresholds).

The user can subsequently implement calculations on a single character or a group of like-characters to guarantee precision within or between symbols, irrespective of color, location, shape or size. The Auto-POI system supplies comprehensive data via ProMetric Software, comprising average luminance across characters, color value, dominant wavelength, and points of minimum and maximum luminance.

Auto-POI applies to all backlit symbols such as buttons and symbols on center stacks and additional sections of the vehicle interior. For backlit modules, a combination of measurements can be applied on a single image to assess symbols utilizing Auto-POI, in addition to alternative backlit modules such as halos or light strips around controls, hubs, or panel edges.

Automotive dashboard with lit gages and indicators (left) and in-vehicle backlit controls and decorative modules (right).

Automotive dashboard with lit gages and indicators (left) and in-vehicle backlit controls and decorative modules (right).

Utilizing Auto-POI, manufacturers can efficiently quantify and evaluate multiple sets of symbols simultaneously and within a wide-area image, without drawing static POI, which is dependent on fixed spatial tolerances.

Utilizing Auto-POI, manufacturers can efficiently quantify and evaluate multiple sets of symbols simultaneously and within a wide-area image, without drawing static POI, which is dependent on fixed spatial tolerances.

Near-IR Sensing for Security, Safety, and Multi-Modal Control

Novel 3D sensing applications, including eye-tracking, facial recognition, gesture recognition, utilize near-infrared (NIR) wavelengths of light. Because these wavelengths are not visible to the human eye,  ensuring the safety of NIR emitters is critical. Radiant’s NIR Intensity Lens solution offers comprehensive evaluation of “flood” sources and dot patterns utilized by these systems to detect driver presence, awareness, and commands.

Camera Monitor Systems (CMS)

Electronic-display-based camera monitor systems (CMS) are beginning to take the place of mirrors for observing external vehicle scenes. Adopted by several countries, standard ISO 16505:20151 and UN Regulation No.46 are the first to allow the legally required mirrors in passenger and commercial vehicles to be replaced by CMS. However, CMS systems need to pass tests to assess the visual performance of the display to map the real-world scene captured outside the vehicle.

Radiant ProMetric Imaging Colorimeters and Photometers coupled with TrueTest Software constitute a solution for CMS display testing that comprises advantages for testing efficiency (performing all display measurements using a single solution), CIE-matched color evaluation, high-resolution imaging for testing MTF at necessary distances, angular performance quantification for uniformity at multiple viewing directions (utilizing the Radiant FPD Conoscope Lens), and a comprehensive CMS software test suite.

Rear-view backup camera, just one type of CMS being introduced into vehicles.

Rear-view backup camera, just one type of CMS being introduced into vehicles.

These Radiant solutions help to guarantee the highest performance, driver experience, and safety of vehicles of present and future. If a measurement solution is required for the lab or in production quality control, Radiant has an Automotive Solutions Team that can help locate a comprehensive system for accelerating any project.

Acknowledgments

Produced from materials originally authored by Anne Corning from Radiant Vision Systems.

This information has been sourced, reviewed and adapted from materials provided by Radiant Vision Systems.

For more information on this source, please visit Radiant Vision Systems.

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