IEC TR 63676-1:2026

IEC TR 63676-1 ®
Edition 1.0 2026-10
TECHNICAL
REPORT
Multimedia systems and equipment for vehicles - External visual systems of
external human-machine interfaces (eHMI) for automated vehicles -
Part 1: General
ICS 33.160.60  ISBN 978-2-8327-1547-5

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CONTENTS
FOREWORD . 2
INTRODUCTION . 4
1 Scope . 5
2 Normative references . 5
3 Terms, definitions and abbreviated terms . 5
3.1 Terms and definitions. 5
3.3 Abbreviated terms . 5
4 Overview . 6
4.1 General . 6
4.2 Various components of multimedia systems . 6
4.2.1 Visual display panels and modules . 6
4.2.2 LED lighting systems . 7
4.3 Study of external lighting colours . 8
5 External display types. 9
5.1 Dynamic segment lights . 9
5.2 Window transparent display . 10
5.3 External display on the front board or bumper . 11
5.4 Projection display . 11
6 Multimedia performance required by external display . 12
6.1 General . 12
6.2 Brightness and contrast ratio . 12
6.3 Colour gamut and grey scale . 12
6.4 Viewing angle . 13
7 Potential new work items . 13
Bibliography . 14

Figure 1 – Example of light positions . 7
Figure 2 – Exterior lighting for automated driving in California and Nevada (USA) . 8
Figure 3 – Example of notice display attached on the rear window . 10
Figure 4 – Example of the display on the front bumper . 11
Figure 5 – Example of a dynamic air pollution display included in the license plate . 11
Figure 6 – Example of various display methods on the road . 12

Table 1 – Example types of eHMI for V2P scenarios . 6
Table 2 – Evaluation results for colour under consideration . 9
Table 3 – Exterior turn signals that light up in sequence . 9

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Multimedia systems and equipment for vehicles - External visual systems
of external human-machine interfaces (eHMI) for automated vehicles -
Part 1: General
FOREWORD
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IEC TR 63676-1 has been prepared by IEC technical committee 100: Audio, video and
multimedia systems and equipment. It is a Technical Report.
The text of this Technical Report is based on the following documents:
Draft Report on voting
100/4530/DTR 100/4583/RVDTR
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Report is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at https://www.iec.ch/members_experts/refdocs. The main document types developed by IEC
are described in greater detail at https://www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under https://webstore.iec.ch in the data related to
the specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
INTRODUCTION
The concept of an external human-machine interface (eHMI) multimedia system in automated
vehicles involves using external displays or communication channels to interact with
pedestrians or other road users. The eHMI aims to enhance communication, safety, and mutual
understanding between automated vehicles and their surroundings.
An example of an eHMI multimedia system could be external displays on the vehicle's exterior,
such as LED panels, OLED displays, LCDs, or projection systems, to convey messages or
signals to pedestrians. For instance, an automated vehicle might display a message or
animation on its external display, indicating that it has detected other road users and will yield
the right of way. This helps pedestrians and road users understand the vehicle’s intentions and
facilitates safer interactions on the road.
It is intended that this series of documents consist of the following parts:
1. Overview of the eHMI for automated vehicles as a first part and it is a Technical Report:
This document introduces the eHMI concept and its importance in the context of automated
vehicles. It highlights the major components of the system and discusses the performance of
implementing external visual systems in such vehicles.
2. Multimedia system process as a second part:
It is intended that this part describes the architecture of external visual systems used in the
eHMI multimedia systems. This could involve discussing the integration of external displays,
LED panels, OLED displays, LCDs, projection systems, and other visual communication
methods into vehicle design.
3. Multimedia system requirements for human factors and user experience as a third part:
It is intended that this part addresses human factors considerations, such as the legibility,
visibility, and comprehension of the displayed information by pedestrians and other road users.
It discusses design principles and guidelines to ensure effective communication and user-
friendly experiences.
Overall, eHMI multimedia systems in automated vehicles aim to build trust, enhance
communication, and improve safety between vehicles and their external environment by using
visual, auditory, or other interactive means to convey information effectively.
This document introduces various external visual systems for multimedia services in automated
vehicles, explains how to assess the impact during development, and summarises new work
items in the near future.
1 Scope
This document describes the system overview of external visual systems of external human-
machine interfaces (eHMIs). These systems are specifically designed for use in automated
vehicles. It provides an introduction and background information on the concept of eHMIs,
highlighting their significance in the context of automated vehicles. Additionally, it describes the
architecture and key components of external visual systems used in eHMI multimedia systems.
It does not deal with:
a) external display usage scenario;
b) UX and UI of external display;
c) hardware performance of eHMI;
d) eHMI regulation of automated vehicle;
e) special vehicle conditions that use eHMI external displays, such as trucks, ambulances, fire
engines, buses, and taxis.
2 Normative references
There are no normative references in this document.
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
– IEC Electropedia: available at https://www.electropedia.org
– ISO Online browsing platform: available at https://www.iso.org/obp
3.2
viewing angle
maximum angle at which the screen can be viewed with acceptable visual performance
3.3 Abbreviated terms
eHMI external human-machine interface
ADS automated driving system
CVD colour vision deficiency
CHMSL centre high-mounted stop light
LED light-emitting diode
RCL rear combination lights
SAE Society of Automotive Engineers
SDV software defined vehicle
UNECE United Nations Economic Commission for Europe
V2P vehicle to pedestrian
4 Overview
4.1 General
External displays or LED-based lighting systems on automated vehicles can be vital for
enhancing communication with pedestrians, cyclists, and other road users. These systems are
designed to ensure mutual understanding and safe interaction, compensating for the lack of
human drivers who typically communicate intentions through eye contact, gestures, or facial
expressions. The performance of external displays and LED lighting systems is intended to
provide clear, intuitive signals that help road users anticipate and understand the vehicle’s next
move, fostering a sense of trust and predictability. Displays and LEDs are not a standalone
system, but parts of an integrated multimedia setup designed to convey communication content
effectively. Multimedia systems combine clear feedback to ensure clear, reliable
communication.
4.2 Various components of multimedia systems
4.2.1 Visual display panels and modules
External displays can be LED displays, OLED displays, and LCDs strategically positioned on
the front grille, side panels, or rear window of the vehicle. Designs vary greatly, i
...