AUTOMOTIVE DISPLAY
Displays in cars serve as instrument clusters (IC) or head-up displays (HuD) to show important information to the driver, as central information displays (CID), or as passenger or rear seat displays for entertainment. Sometimes they even replace mirrors and serve as camera surveillance displays. Especially in cars, there are no limits to form factors and 3D shapes. They sometimes have various features such as image enhancement, privacy modes or anti-glare features. All of these displays must be of high quality to withstand significant temperature differences, virbations and shocks and need to display content under changing lighting conditions. They must also be able to be viewed from different angles to accommodate different sizes, positions, and passengers.
Measurement tasks
The German Flat Panel Display Forum (Deutsches Flachdisplay Forum, external link), a leading expert network in the field of displays, has developed recommendations for automotive displays together with the OEM working group. These include specification values and methods for optical tests. They apply to all types of automotive displays. Examples are:
- OEM Specification
- DFF OLED Specification
- DFF BlackMURA
- DFF Gamma
- DFF Sticking Image (3-level)
- Angular OEM Regions
Premium manufacturers in particular have drawn up additional specifications to ensure readability and the highest optical quality. Many of these measurements were devloped, evaluated and/or researched in projects together with TechnoTeam. These include, for example the follwoning measurement tasks:
- Display Sparkle for anti glare layers (AGL)
- Sticking Image (2-level)
- Reflection for contrast under ambient light (sun light)
- Resolution by Pixel Cross Talk
- Resolution by Slanted Line MTF (Modulation Transfer Function)
- Halo for Full Area Local Dimming Display (FALD)
- Any measurement item from a vantage point as e.g. driver and passenger
Our solutions
TechnoTeam offers a wide array of lenses and specialized add-ons to ensure fast and reproducible measurements according to all these requirements and methods. Our dedicated robotic-based ILMD system, the LMK Position - can ensure fast and highly reproducible alignment of various shapes, including ultra-wide screens and free-form shapes common in modern cars. For more information on the specific products and applications, please refer to the dedicated information shown below:
RELEVANT PRODUCTS
RELEVANT PUBLICATIONS
Improvements for Automotive LCDs: Image Enhancement and Local Dimming (FALD)
International Display Workshop (IDW 2023)
Automotive displays must fulfill high requirements including outstanding optical performance. We report on the reduction of power consumption by image enhancement improving bright readability and by local dimming of LCDs (FALD). We also address halo and non-uniformity effects for FALD, which reduce image quality, by measurements and thresholds for perception.
Invited Paper: Fast and Robust High Precision Luminance Image Stitching in Uniformity and DeMURA measurements
International Conference on Display Technology (ICDT 2023)
This paper provides an overview of image stitching and its general advantages and challenges. Further, we introduce a novel stitching concept based on our advanced pixel registration (APR) procedure. It allows easy and comparable flexible stitching setups for DeMURA and uniformity measurements in laboratory and production environments.
Sparkle measurements for an automotive specification: Evaluation method for flexible setup conditions
Journal of the Society for Information Display
This contribution proposes a sparkle evaluation based on a spatial frequency filter, taking into account various setup influences. Furthermore, the effect of flexible setup conditions on the reproducibility of measurement results is investigated. The procedure and concepts are derived for sampling resolutions between 15 and 30 cpx/mm with display pixel pitches between 183 and 224 ppi and validated by a round-robin experiment with different test devices, including glass and foil-based Anti-Glare Layers. The findings serve as a basis for the measurement conditions of an automotive display sparkle measurement specification.
Advanced Alignment and Metrology Concepts Using Photometric Robotics with Examples for Automotive Displays
International Conference on Display Technology (ICDT 2021)
The alignment quality and reproducibility in ILMD (Imaging Luminance Measurement Device) based display metrology has a great influence on the reproducibility of the obtained measurement data. In this context, this contribution outlines and introduces several advanced measurement and alignment concepts that can be performed with “photometric robotics”. The term describes machine vision performed with an ILMD supported by robotic movements.
Distinguished Paper: Short Distance Uniformity and BlackMURA Measurements
Journal of the Society for Information Display
The increasing display sizes and changing form factors of displays, including automotive displays, lead to impractical measurement distances for lateral uniformity measurements. This contribution suggests and exemplarily applies two alternative and combinable methods to allow lateral uniformity measurements at low distances and describes an adjusted BlackMURA compliant validation procedure. The proposed methods are validated with a high-quality display device and are compared to results using the standard long-distance measurement procedure.
Current Standardization Efforts and Measurement Procedures of German Flat Panel Forum (DFF) for Automotive OLED Displays
SID Vehicle Displays & Interfaces 2021
With increasing performance parameters and decreasing costs OLED displays are getting more relevant for premium automotive application. Therefore, the German Flat Panel Forum (DFF) extends its current LCD specification and measurement methods to also cover OLED displays. Challenges and solutions for lifetime, Burn-In (Image Sticking) and viewing angle procedures are presented more in detail.
Conoscopic measurements for displays – advantages and limitations
electronic displays Conference 2016
Measurements with conoscopic lenses together with ILMDs (Imaging Luminance/Color Measuring Devices) can support the characterisation of displays and materials during the R&D and production process. Using a conoscopic lens the angular dependence of luminance/color can be measured with only a single measurement. Using different geometrical relations between the device under test, the conoscopic lens and different illumination conditions a lot of display and material properties can be measured with one or a few measurements only. The article shows the working principle of conoscopic lenses in detail. Furthermore the measurement of the angular dependent luminance/color, the angular dependent contrast and the measurement of selected angular dependent material properties (e.g. transmission and reflection characteristics of glasses) are presented. For all applications the advantages and limitations of the conoscopic lens measurements are explained to suggest the right fields of application for this measurement method.
Non-uniformity correction in recent automotive image sticking evaluation methods
SID Vehicle Displays & Interfaces 2019
Modern automotive displays may be sensitive to static content, which remains as an undesired effect of either temporary vanishing or being a static ghost image within the refreshed content. Therefore, there is a development of measurement procedures to quantize the degree of image sticking [1- 6]. Different aspects of these methods as the grey level dependencies or the importance of a temp-oral alignment were considered in [7]. But the mathematically necessary separation of unavoidable initial non-uniformities and the actual image sticking was excluded in that research.
This contribution concentrates on the performance of two selected image sticking evaluation methods [5, 6] from the automotive community and [1] for reference. After briefly introducing the three methods, this contribution focusses on their capability of separating initial non-uniformities from the actual sticking image effect of the target display. Therefore, a mathematical analysis, which is based on a simple but physically motivated sticking image model, is performed. Based on that, an additional non-uniformity correction is proposed. This additional correction has a positive influence on the precision but a negative influence on the measurement time of the fastest measurement method [6]. Thus, we propose a workflow, that decides based on the properties of the DUT whether the correction is necessary or not. All conclusions are supported by simulations and validated using measurement results of a randomly chosen non-uniform automotive LC display.
The aim of this paper is on the one hand to quantize the mathematical influence of the methods and on the other hands to suggest a workflow, which utilizes an existing method and optimizes its application with respect to precision and overall measurement time.
This contribution concentrates on the performance of two selected image sticking evaluation methods [5, 6] from the automotive community and [1] for reference. After briefly introducing the three methods, this contribution focusses on their capability of separating initial non-uniformities from the actual sticking image effect of the target display. Therefore, a mathematical analysis, which is based on a simple but physically motivated sticking image model, is performed. Based on that, an additional non-uniformity correction is proposed. This additional correction has a positive influence on the precision but a negative influence on the measurement time of the fastest measurement method [6]. Thus, we propose a workflow, that decides based on the properties of the DUT whether the correction is necessary or not. All conclusions are supported by simulations and validated using measurement results of a randomly chosen non-uniform automotive LC display.
The aim of this paper is on the one hand to quantize the mathematical influence of the methods and on the other hands to suggest a workflow, which utilizes an existing method and optimizes its application with respect to precision and overall measurement time.
Requirements on the characterization of optical display attributes for automotive applications
SID Vehicle Displays & Interfaces 2018
There are several optical display attributes, which require optical and photometric measurements during R&D activities or quality control and conformity assessment for automotive applications. The aim of this research paper is to assess typical properties of luminance based display measurements with respect to different optical display attributes. The measurement properties include on the one hand characteristics of the measurement equipment and on the other, the characteristics of the measurement method.
Based on the general working principle of ILMDs (imaging luminance measurement device), we briefly explain typical ILMD characteristics as well as the concepts of repeatability, reproducibility, precision and measurement uncertainty [1]. Afterwards, optical display properties as well as measurement methods [2, 3, 4] are introduced.
Finally, we qualitatively and quantitatively assess chosen influences of ILMD specifications and different measurement procedures on the obtained results.
Thus, this work shall convey a feeling for photometric display metrology requirements under the consideration of the measurement task and the desired precision
Based on the general working principle of ILMDs (imaging luminance measurement device), we briefly explain typical ILMD characteristics as well as the concepts of repeatability, reproducibility, precision and measurement uncertainty [1]. Afterwards, optical display properties as well as measurement methods [2, 3, 4] are introduced.
Finally, we qualitatively and quantitatively assess chosen influences of ILMD specifications and different measurement procedures on the obtained results.
Thus, this work shall convey a feeling for photometric display metrology requirements under the consideration of the measurement task and the desired precision
Repeatability and Reproducibility Considerations for BlackMURA Measurements
Proceedings of the International Display Workshops Volume 26 (IDW '19)
The “Uniformity measurement standard for Displays”, which is used for automotive applications, describes precise setup and alignment procedures to ensure reproducible measurement results. However, the influences of the tested device and the ILMD are not considered in detail. This contribution shows experiments and simulations to estimate these influences as well.
Invited Paper: Recent Standardization Efforts and Measurement Procedures of German Automotive OEM and German Flat Panel Forum (DFF)
SID International Symposium 2016
The requirements of automotive displays differ to a large extent from consumer and industrial displays. In order to reduce the effort in specifying and evaluating high quality displays, German automotive OEMs, Tier 1/2 and the German Flat Panel Forum have launched a cooperation.