Ergonomics of human-system interaction — Part 380: Survey result of HMD (Head-Mounted Displays) characteristics related to human-system interaction

This document provides information based on a study of the characteristics of head-mounted displays (HMDs) regarding the ergonomics of human–system interaction. Although this document covers the broad range of ergonomics issues that arise, it specifically provides more-detailed information about the visual aspects of the interaction, and it provides information that could form the basis for future possible standards related to HMDs. NOTE: It is preferable to take systematic approach to consider characteristics of HMD, since HMD affects a viewer not only by visual aspects, but also by some other physical aspects.

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ISO/TR 9241-380:2022 - Ergonomics of human-system interaction — Part 380: Survey result of HMD (Head-Mounted Displays) characteristics related to human-system interaction Released:14. 06. 2022
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TECHNICAL ISO/TR
REPORT 9241-380
First edition
2022-06
Ergonomics of human-system
interaction —
Part 380:
Survey result of HMD (Head-Mounted
Displays) characteristics related to
human-system interaction
Reference number
ISO/TR 9241-380:2022(E)
© ISO 2022
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ISO/TR 9241-380:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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© ISO 2022 – All rights reserved
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ISO/TR 9241-380:2022(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction .............................................................................................................................................................................................................................. vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

4 Head-mounted displays (HMDs) ......................................................................................................................................................... 2

5 Categories of HMDs............................................................................................................................................................................................3

5.1 General ........................................................................................................................................................................................................... 3

5.2 Categorized by virtual image .................................................................................................................................................... 5

5.2.1 VR type ........................................................................................................................................................................................ 5

5.2.2 AR type ........................................................................................................................................................................................ 5

5.2.3 MR type ....................................................................................................................................................................................... 5

5.3 Categorized by virtual image formation ......................................................................................................................... 6

5.3.1 Imaging display and optics ....................................................................................................................................... 6

5.3.2 Scanning type........................................................................................................................................................................ 6

5.3.3 Light field fype ..................................................................................................................................................................... 6

5.3.4 Holographic display with waveguide type .................................................................................................. 7

5.4 Categorized by ocularity ............................................................................................................................................................... 8

5.4.1 Binocular ................................................................................................................................................................................... 8

5.4.2 Biocular ...................................................................................................................................................................................... 9

5.4.3 Monocular ........................................................................................................................................... ...................................... 9

5.5 Categorized by physical configuration ............................................................................................................................. 9

5.5.1 Eyeglasses type ................................................................................................................................................................... 9

5.5.2 Placed on eyeglasses ....................................................................................................................................................... 9

5.5.3 Frame plus optical device ........................................................................................................................................ 10

5.5.4 Goggles ..................................................................................................................................................................................... 10

5.5.5 Smart phone with box ................................................................................................................................................. 10

5.5.6 Helmet mounted .............................................................................................................................................................. 11

5.6 Categorized by system configuration ............................................................................................................................. 11

5.6.1 Wireless HMD (standalone) ................................................................................................................................... 11

5.6.2 Smart phone with special optics .......................................................................................................................12

5.6.3 Wired HMD ...........................................................................................................................................................................12

5.7 Categorized by physical input devices for HMD system .................................................................................12

5.7.1 HMD System without external physical input devices ..................................................................12

5.7.2 HMD System with external physical input devices ..........................................................................12

6 HMD human-system interaction characteristics ...........................................................................................................13

6.1 Optical characteristics ................................................................................................................................................................. 13

6.1.1 General .....................................................................................................................................................................................13

6.1.2 Distance between eyes............................................................................................................................................... 18

6.1.3 Distortion and aberration ....................................................................................................................................... 18

6.1.4 Inter-Ocular optical properties .......................................................................................................................... 21

6.1.5 For AR/MR ............................................................................................................................................................................ 26

6.1.6 For AR ........................................................................................................................................................................................29

6.1.7 For AR, video see-through properties ..........................................................................................................30

6.1.8 For light field display ...................................................................................................................................................30

6.2 HMD system-related characteristics ............................................................................................................................... 31

6.2.1 Time delay of HMD system (latency) ............................................................................................................ 31

6.2.2 Degree of freedom ......................................................................................................................................................... 32

6.3 Other characteristics of HMD .................................................................................................................................................33

6.3.1 Physical properties........................................................................................................................................................33

6.3.2 Alignment ..............................................................................................................................................................................34

6.4 Physical conditions of a viewer .............................................................................................................................................34

iii
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ISO/TR 9241-380:2022(E)

6.4.1 Age ...................................................................... ..........................................................................................................................34

6.4.2 Habituation ........................................................................................................................................................................... 35

6.4.3 Preference ............................................................................................................................................................................. 35

6.4.4 Duration .................................................................................................................................................................................. 35

6.4.5 Posture of a user .............................................................................................................................................................. 35

6.5 Presence and immersion ............................................................................................................................................................ 35

7 Visual induced motion sickness (VIMS) ...................................................................................................................................35

7.1 General ........................................................................................................................................................................................................ 35

7.2 SSQ .................................................................................................................................................................................................................. 35

7.3 VIMS related factors ....................................................................................................................................................................... 36

8 Consideration .......................................................................................................................................................................................................36

Annex A (informative) Visual Fatigue and Discomfort..................................................................................................................37

Bibliography .............................................................................................................................................................................................................................39

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ISO/TR 9241-380:2022(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 4,

Ergonomics of human-system interaction.
A list of all parts in the ISO 9241 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www.iso.org/members.html.
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ISO/TR 9241-380:2022(E)
Introduction

The evolution of electronic devices has led to the growing popularity of head-mounted displays (HMDs)

for direct human–machine interaction. Although ISO 9241-303 and ISO 305 addressed HMDs as ‘virtual

displays’, the information in these documents was limited to devices available at the time, and the

evolution of HMDs requires new parameters to cover the interactions between the user and the HMD

itself. To provide the latest information to suppliers, users, and anyone who interacts with HMDs, it is

important to establish which HMD characteristics need to be considered.

Unlike a conventional display, a viewer wears an HMD to see the displayed images. In most cases,

when images are shown on a conventional display, there is a certain distance between the viewer and

display. However, as stated, a viewer of an HMD wears it, usually on their head. Obviously, such viewing

conditions affect the viewer in certain ways, by not only the optical characteristics (which are the main

concerns for conventional displays) but also other physical characteristics such as weight. Therefore,

discussing the ergonomic considerations of HMDs requires a systematic approach by considering

several aspects simultaneously, which is the aim of this document.

NOTE The International Electrotechnical Commission (IEC) also works on the standardization of HMDs (the

IEC calls them 'eyewear displays'). At the time of publication, the following IEC standards are available and are

being developed:
IEC TR 63145-1-1: 2018: Eyewear display - Part 1-1: Generic introduction

IEC 63145-20-10:2019: Eyewear display - Part 20-10: Fundamental measurement methods - Optical

properties

IEC 63145-20-20:2019: Eyewear display - Part 20-20: Fundamental measurement methods - Image quality

IEC 63145-22-10:2020: Eyewear display - Part 22-10: Specific measurement methods for AR type - Optical

properties
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TECHNICAL REPORT ISO/TR 9241-380:2022(E)
Ergonomics of human-system interaction —
Part 380:
Survey result of HMD (Head-Mounted Displays)
characteristics related to human-system interaction
1 Scope

This document provides information based on a study of the characteristics of head-mounted displays

(HMDs) regarding the ergonomics of human–system interaction. Although this document covers the

broad range of ergonomics issues that arise, it specifically provides more-detailed information about

the visual aspects of the interaction, and it provides information that could form the basis for future

possible standards related to HMDs.

NOTE It is preferable to take systematic approach to consider characteristics of HMD, since HMD affects a

viewer not only by visual aspects, but also by some other physical aspects.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
head-mounted display
HMD

electronic device that shows information on one or more displays attached to the head of a human

3.2
virtual reality
artificial environment presented by a computer
Note 1 to entry: See Figure 1.

Note 2 to entry: Including telepresence and interaction with and reaction from the virtual environment.

[SOURCE: ISO/IEC TR 18121:2015, 3.6]
3.3
mixed reality
physical and digital (virtual) objects co-exist and interact in real time
Note 1 to entry: See Figure 1.
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3.4
augmented reality
reality that has virtually added information
Note 1 to entry: See Figure 1.
Note 2 to entry: AR is used in ISO 9241-910 with no definition.
Note 3 to entry: AR is used in ISO/IEC TR 18120:2016 with no definition.
Note 4 to entry: AR is used in ISO 19154:2017 with no definition.
Note 5 to entry: AR is used in ISO/IEC TR 19566-1:2017 with no definition.
3.5
reality
world or the state of things as they exist
Figure 1 — VR, MR, AR, Reality
Note 1 to entry: See Figure 1.
3.6
exit pupil
vertical/horizontal dimension of the QVS (qualified viewing space)
[SOURCE: ISO 9241-302]
4 Head-mounted displays (HMDs)

An HMD is an electronic display device that provides visual information by using one or more displays

that are placed on a human head and secured by elastic straps or earpieces or integrated in a helmet

(see Figure 2). An HMD shows information by using virtual images rather than real ones (see Figure 3).

Most HMDs consist of one or more electronic displays and proper optics that treat the images on the

display or displays so that they can be seen by one or more human eyes. In some cases, there is no

physical display, only optics (see Figure 4). Because of these considerable differences from conventional

displays, numerous characteristics need to be considered regarding human–system interaction. This

document explores those characteristics and point out new ways of evaluating HMDs regarding their

users (viewers).
Figure 2 — Example of a head-mounted display
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ISO/TR 9241-380:2022(E)
Key
1 virtual image
2 real image on a display
3 convex lens
Figure 3 — Example of a virtual image
Key
1 laser source
2 mirror array
3 half mirror
4 real object
5 virtual image (projected image)
Figure 4 — Example of a direct scanning HMD
5 Categories of HMDs
5.1 General

There are several ways to categorize HMDs, such as by the type of images that the device shows, how

the device forms a virtual image, ocularity, and physical configuration (Figure 5)

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ISO/TR 9241-380:2022(E)
Figure 5 — Example of categorizing HMDs
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ISO/TR 9241-380:2022(E)
5.2 Categorized by virtual image
5.2.1 VR type

The VR type of HMD displays only computer-generated images (virtual images). The HMD covers the

viewer’s eyes completely, meaning that they can see nothing except the displayed images (see Figure 6).

Figure 6 — Example of a VR HMD
5.2.2 AR type

The AR type of HMD presents images of the real surrounding environment by using either transparent

optics (see-through AR type) or electro-optical devices, such as a video camera (video-see-through

type), and it shows computer-generated images (virtual images) by using certain electro-optical devices

(see Figure 7).
Figure 7 — Example of an AR type HMD
5.2.3 MR type

The MR type of HMD presents mainly computer-generated images and imposes real images (outside

scenery) by means of either video see-through or see-through optics (see Figure 8).

Figure 8 — Example of an MR type
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5.3 Categorized by virtual image formation
5.3.1 Imaging display and optics

This type of HMD shows virtual images by both showing them on displays and forming them by using

optics (see Figure 9).
Key
1 virtual image
2 displays with real image
3 convex lenses
Figure 9 — Example of an image forming type
5.3.2 Scanning type

This type of HMD does not form images by any means; rather, it uses light rays to scan the human retina

via certain optics (see Figure 4).
5.3.3 Light field fype

The light-field approach involves providing a near-eye display by using certain optics, such as those

based on micro-lenses (see Figure 10).
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Key
1 LCD
2 micro lens array
3 half mirror
4 real object
5 virtual image (projected image)
Figure 10 — Example of a light field display
5.3.4 Holographic display with waveguide type

holographic with waveguide to provide near-eye display by using certain optics, such as micro lens-

based optics (See Figure 11).
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ISO/TR 9241-380:2022(E)
Key
1 light guiding element
2 LCD
3 real object
4 virtual image (projected image)
Figure 11 — Example of a holographic with waveguide display
5.4 Categorized by ocularity
5.4.1 Binocular

The binocular type of HMD shows independent images on each imaging device by using stereo

separation and stereo convergence (see Figure 12).
NOTE Two separate images are seen using two separate displays and lenses.
Figure 12 — Example of a binocular display
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ISO/TR 9241-380:2022(E)
5.4.2 Biocular

The bi-ocular type of HMD shows the same images on each imaging device (see Figure 13).

NOTE One image is seen using one display through two separate mirrors and lenses.

Figure 13 — Example of a biocular display
5.4.3 Monocular
The monocular type of HMD shows images on one imaging device (see Figure 14).
NOTE seeing one image by using one display and one lens
Figure 14 — Example of a monocular display
5.5 Categorized by physical configuration
5.5.1 Eyeglasses type

This type of HMD is somewhat like typical eyeglasses, having optics, a frame, a bridge over the nose and

arms that rest on the ears (see Figure 15).
NOTE Eyeglasses that have a display
Figure 15 — Example of eyeglasses type of HMD
5.5.2 Placed on eyeglasses
This type of HMD is designed to be put onto eyeglasses (see Figure 16).
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ISO/TR 9241-380:2022(E)
NOTE Display with optics on eyeglasses.
Figure 16 — Example of type of HMD that is placed on eyeglasses
5.5.3 Frame plus optical device

This type of HMD has a frame for mounting on the viewer’s head and one or more optical devices

attached to that frame (see Figure 17).
NOTE Display and optics on an eyewear frame.
Figure 17 — Frame and optical devices type
5.5.4 Goggles
HMD looks like goggles (see Figure 18).
Figure 18 — Example of a goggle-type HMD
5.5.5 Smart phone with box
This type of HMD consists of a smartphone and a box (see Figure 19).
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ISO/TR 9241-380:2022(E)
Figure 19 — Smart phone with box type
5.5.6 Helmet mounted

This type of HMD is attached to a helmet and is usually called a ‘helmet-mounted display’ (see Figure 20).

Figure 20 — Example of a helmet-mounted HMD
5.6 Categorized by system configuration
5.6.1 Wireless HMD (standalone)
HMD works without having any other connected devices such as PC (see Figure 21).
NOTE HMD has only a wireless connection.
Figure 21 — example of a wireless HMD
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ISO/TR 9241-380:2022(E)
5.6.2 Smart phone with special optics

This type of HMD consists of a smartphone and certain special optics (see Figure 19).

5.6.3 Wired HMD

This type of HMD is connected by a wire to another device such as a PC (see Figure 22).

NOTE HMD with a wired connection.
Figure 22 — Example of a wired HMD
5.7 Categorized by physical input devices for HMD system
5.7.1 HMD System without external physical input devices

This type of HMD system has no external physical input devices, such as remote control (see Figure 23).

Figure 23 — Example of an HMD without external physical input devices
5.7.2 HMD System with external physical input devices

This type of HMD system has external physical input devices, such as one or more wands, a steering

wheel and/or gesture-based interaction devices, such as data gloves with motion tracking (see

Figure 24).
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ISO/TR 9241-380:2022(E)
a) HMD system with wireless wands b) HMD system with steering wheel
Figure 24 — Examples of an HMD with external physical input devices
6 HMD human-system interaction characteristics
6.1 Optical characteristics
6.1.1 General
Figure 25 shows the principles of an HMD.
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ISO/TR 9241-380:2022(E)
Key
1 field of view
2 display
3 optical components
4 exit pupil
5 eye relief (see 6.1.1.5)

Figure 25 — HMD using a lens to create a virtual image from a micro-display (ISO 9241-302,

Figure 11 therein)
6.1.1.1 Focus

This is defined as the point where the geometrical lines or their prolongations conforming to the

rays diverging from or converging toward another point intersect and give rise to an image after

reflection by a mirror or refraction by a lens or optical system (see Figure 27); modified from

ISO 9241-302:2008, 3.5.24, which is based on the Merriam-Webster dictionary.

Note The definition of focal distance in ISO 9241-302:2008, 3.5.24 was incorrect.

The figure for focal distance in ISO-9241-302 (see Figure 26) was not expressed properly and will be

replaced by Figure 27 in this document.
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ISO/TR 9241-380:2022(E)
Key
1 display
2 apparent focal points
Figure 26 — Focus distance (ISO 9241-302) ; not expressed correctly
Note Focus distance is not correctly expressed by Figure 26.
Key
1 positive lens magnifier
2 object
3 virtual image
Figure 27 — Focus
6.1.1.2 Field of view (FOV)

For a conventional display, the FOV—that is. the width to which an image from a display spread—

is defined by the visual angle subtended by the image at the eye pupil (see Figure 28). However, for

an HMD, its viewer sees an image as a virtual one, so this definition is not directly applicable. For a

detailed discussion, see Section 5.2 of IEC 63145-1-1. As stated in IEC 63145-1-1, the FOV is related to

the followi
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