IEC TS 61496-4-2:2022
(Main)Safety of machinery - Electro-sensitive protective equipment - Part 4-2: Particular requirements for equipment using vision based protective devices (VBPD) - Additional requirements when using reference pattern techniques (VBPDPP)
Safety of machinery - Electro-sensitive protective equipment - Part 4-2: Particular requirements for equipment using vision based protective devices (VBPD) - Additional requirements when using reference pattern techniques (VBPDPP)
IEC TS 61496-4-2:2022 specifies requirements for the design, construction and testing of non-contact electro-sensitive protective equipment (ESPE) designed specifically to detect persons as part of a safety-related system, employing vision-based protective devices (VBPDs) using reference pattern techniques (VBPDPP) for the sensing function. Special attention is directed to features which ensure that an appropriate safety-related performance is achieved. An ESPE can include optional safety-related functions, the requirements for which are given in Annex A of IEC 61496-1:2020 and this document. Where this document does not contain all necessary provisions, then IEC TS 62998-1 applies. It is also possible, for those aspects not considered in this document, to use provisions from IEC TS 62998-1 additionally. This document does not specify the dimensions or configurations of the detection zone and its disposition in relation to hazardous parts for any particular application, nor what constitutes a hazardous state of any machine. It is restricted to the functioning of the ESPE and how it interfaces with the machine. A VBPDPP is defined as consisting of a single image-sensing device viewing on a passive reference pattern as the background and where the detection principle is based on blocking or partially preventing the view of the pattern. Information about the thickness, shape, surface characteristics or location of the object is not required for detection. For multi-image sensing devices, additional techniques, requirements and test procedures can be necessary.
- This document is limited to automatic vision-based ESPEs that do not require human intervention for detection.
- It is limited to automatic vision-based ESPEs that detect objects entering into, or are present in, a detection zone(s).
- It is limited to ESPEs using active illumination technique.
- Excluded from this technical specification are VBPDPPs employing radiation at wavelengths outside the range 400 nm to 1 500 nm.
- This document does not address those aspects required for complex classification or differentiation of the object detected.
This document is relevant for VBPDPPs having a stated detection capability up to 200 mm. This document does not deal with EMC emission requirements.
IEC TS 61496-4-2:2022 cancels and replaces the first edition published in 2014. This edition constitutes a technical revision. This edition includes the following technical changes with respect to the previous edition:
a) Some requirement clauses and test procedures have been adapted or removed because they have been consolidated in IEC 61496-1:2020 (e.g. 5.4.6.2 of IEC 61496-1:2020 Light sources or Clause A.9).
Securité des machines - Equipements de protection électro-sensibles - Partie 4-2: Exigences particulières pour les équipements utilisant des dispositifs protecteurs par vision (VBPD) - Exigences supplémentaires pour l'utilisation de techniques de motifs de référence (VBPDPP)
IEC TS 61496-4-2:2022 est disponible sous forme de IEC TS 61496-4-2:2022 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
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IEC TS 61496-4-2 ®
Edition 2.0 2022-09
TECHNICAL
SPECIFICATION
colour
inside
Safety of machinery – Electro-sensitive protective equipment –
Part 4-2: Particular requirements for equipment using vision based protective
devices (VBPD) – Additional requirements when using reference pattern
techniques (VBPDPP)
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IEC TS 61496-4-2 ®
Edition 2.0 2022-09
TECHNICAL
SPECIFICATION
colour
inside
Safety of machinery – Electro-sensitive protective equipment –
Part 4-2: Particular requirements for equipment using vision based protective
devices (VBPD) – Additional requirements when using reference pattern
techniques (VBPDPP)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.110; 29.260.99 ISBN 978-2-8322-5699-2
– 2 – IEC TS 61496-4-2:2022 © IEC 2022
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 7
3 Terms and definitions . 7
4 Functional, design and environmental requirements . 9
5 Testing . 17
6 Marking for identification and for safe use . 26
7 Accompanying documents . 27
Annex A (normative) Optional functions of the ESPE . 28
Annex B (normative) Catalogue of single faults affecting the electrical equipment of
the ESPE, to be applied as specified in 5.3 . 30
Annex AA (informative) The positioning of VBPD in respect of parts of the human body . 31
Bibliography . 38
Figure 1 – Image planes in VBPDPP . 9
Figure 2 – Side view of VBPDPP using a passive reference pattern . 10
Figure 3 – Light intensity measurement setup for indirect light tests . 23
Figure 4 – Light intensity measurement setup for direct light tests . 24
Figure AA.1 – Minimum distance S – Example 1 . 34
Figure AA.2 – Overall minimum distance S without tolerance zone – Example 1 . 34
o
Figure AA.3 – Overall minimum distance S including tolerance zone – Example 1 . 35
o
Figure AA.4 – Minimum distance S – Example 2 . 36
Figure AA.5 – Overall minimum distance S without tolerance zone – Example 2 . 37
o
Figure AA.6 – Overall minimum distance S including tolerance zone – Example 2 . 37
o
Table 421 – Verification of detection capability requirements (see also 4.2.12) . 18
Table 422 – Overview of light interference tests . 21
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SAFETY OF MACHINERY –
ELECTRO-SENSITIVE PROTECTIVE EQUIPMENT –
Part 4-2: Particular requirements for equipment
using vision based protective devices (VBPD) –
Additional requirements when using reference
pattern techniques (VBPDPP)
FOREWORD
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rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC TS 61496-4-2 has been prepared by IEC technical committee TC 44: Safety of machinery
– Electrotechnical aspects. It is a Technical Specification.
This second edition cancels and replaces the first edition published in 2014. This edition
constitutes a technical revision.
This edition includes the following technical changes with respect to the previous edition:
a) Some requirement clauses and test procedures have been adapted or removed because
they have been consolidated in IEC 61496-1:2020 (e.g. 5.4.6.2 of IEC 61496-1:2020 Light
sources or Clause A.9)
– 4 – IEC TS 61496-4-2:2022 © IEC 2022
The text of this document is based on the following documents:
Draft Report on voting
44/933/DTS 44/955A/RVDTS
Full information on the voting for the approval of this document can be found in the report on
voting indicated in the above table.
The language used for the development of this document 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 www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at http://www.iec.ch/standardsdev/publications.
This document is to be used in conjunction with IEC 61496-1:2020.
This document supplements or modifies the corresponding clauses in IEC 61496-1:2020 to
specify particular requirements for the design, construction and testing of electro-sensitive
protective equipment (ESPE) for the safeguarding of machinery, employing vision based
protective devices (VBPD) using reference pattern techniques (VBPDPP) for the sensing
function.
Where a particular clause or subclause of IEC 61496-1:2020 is not mentioned in this document,
that clause or subclause applies as far as is reasonable. Where this document states "addition",
"modification" or "replacement", the relevant text of IEC 61496-1:2020 is adapted accordingly.
Clauses and subclauses which are additional to those of IEC 61496-1:2020 are numbered
sequentially, following on the last available number in IEC 61496-1:2020. Terminological entries
(in Clause 3) which are additional to those in IEC 61496-1:2020 are numbered starting from
3.4201. Additional annexes are lettered from AA onwards and additional tables are numbered
with prefix 42
A list of all parts in the IEC 61496 series, published under the general title Safety of machinery
– Electro-sensitive protective equipment, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.
INTRODUCTION
An electro-sensitive protective equipment (ESPE) is applied to machinery presenting a risk of
personal injury. It provides protection by causing the machine to revert to a safe condition before
a person can be placed in a hazardous situation.
The working group responsible for drafting this document was concerned that, due to the
complexity of the technology, there are many issues that are highly dependent on analysis and
expertise in specific test and measurement techniques. In order to provide a high level of
confidence, independent review by relevant expertise is recommended. They considered that if
this high level of confidence could not be established these devices would not be suitable for
use in safety related applications.
– 6 – IEC TS 61496-4-2:2022 © IEC 2022
SAFETY OF MACHINERY –
ELECTRO-SENSITIVE PROTECTIVE EQUIPMENT –
Part 4-2: Particular requirements for equipment
using vision based protective devices (VBPD) –
Additional requirements when using reference
pattern techniques (VBPDPP)
1 Scope
Replacement:
This document specifies requirements for the design, construction and testing of non-contact
electro-sensitive protective equipment (ESPE) designed specifically to detect persons as part
of a safety-related system, employing vision-based protective devices (VBPDs) using reference
pattern techniques (VBPDPP) for the sensing function. Special attention is directed to features
which ensure that an appropriate safety-related performance is achieved. An ESPE can include
optional safety-related functions, the requirements for which are given in Annex A of
IEC 61496-1:2020 and this document.
NOTE "Non-contact" means that physical contact is not required for sensing.
Where this document does not contain all necessary provisions, then IEC TS 62998-1 applies.
It is also possible, for those aspects not considered in this document, to use provisions from
IEC TS 62998-1 additionally.
This document does not specify the dimensions or configurations of the detection zone and its
disposition in relation to hazardous parts for any particular application, nor what constitutes a
hazardous state of any machine. It is restricted to the functioning of the ESPE and how it
interfaces with the machine.
A VBPDPP is defined as consisting of a single image-sensing device viewing on a passive
reference pattern as the background and where the detection principle is based on blocking or
partially preventing the view of the pattern. Information about the thickness, shape, surface
characteristics or location of the object is not required for detection. For multi-image sensing
devices, additional techniques, requirements and test procedures can be necessary.
• This document is limited to automatic vision-based ESPEs that do not require human
intervention for detection.
• It is limited to automatic vision-based ESPEs that detect objects entering into, or are present
in, a detection zone(s).
• It is limited to ESPEs using active illumination technique.
• Excluded from this technical specification are VBPDPPs employing radiation at wavelengths
outside the range 400 nm to 1 500 nm.
• This document does not address those aspects required for complex classification or
differentiation of the object detected.
This document is relevant for VBPDPPs having a stated detection capability up to 200 mm.
NOTE The positioning of VBPD in respect of parts of the human body is presented in Annex AA of this document.
This document does not deal with EMC emission requirements.
2 Normative references
Addition:
IEC 60825-1:2014, Safety of laser products – Part 1: Equipment classification and requirements
IEC 61496-1:2020, Safety of machinery – Electro-sensitive protective equipment – Part 1:
General requirements and tests
IEC 62471:2006, Photobiological safety of lamps and lamp systems
ISO 13855:2010, Safety of machinery – Positioning of safeguards with respect to the approach
speeds of parts of the human body
ISO 20471, High-visibility clothing – Test methods and requirements
3 Terms and definitions
This clause of IEC 61496-1:2020 is applicable except as follows:
Replacement:
3.3
detection capability
ability to detect the specified test pieces (see 4.2.13) in the specified detection zone
Note 1 to entry: Detection capability is generally measured by the size of object that can be detected. An increase
in detection capability means that a smaller object can be detected.
[SOURCE: IEC 61496-1:2020, 3.3, modified – The text has been changed to make it more
relevant to vision based sensors and Note 1 has been added]
Additions:
3.4201
image
snap shot representation of the scene in different planes of the VBPDPP in the form of a two
dimensional matrix
3.4202
imaging sensor
optoelectronic device which produces electrical signals representing the characteristics of an
image
3.4203
passive reference pattern
static (i.e. fixed location and not changing) regular (periodic) combination of pattern elements
on a background that covers at least the detection zone and the tolerance zone – blocking the
view of part of the pattern causes detection
Note 1 to entry: Regularity of the pattern refers only to the physical pattern and not to the image of the pattern as
seen by the imaging sensor.
3.4204
pattern element
local part of the passive reference pattern
EXAMPLE Black and white checker board – one black square or one white square.
– 8 – IEC TS 61496-4-2:2022 © IEC 2022
3.4205
pixel,
smallest light sensitive element of an imaging sensor array
3.4206
pixel,
area of the smallest element that can be distinguished from its neighbouring elements
3.4207
sensing zone
three-dimensional volume defined by the field of view of the image sensor and with the apex at
the optical window of the sensing device
Note 1 to entry: The volume could be in the shape of a pyramid or cone.
Note 2 to entry: A zone of limited detection capability, a detection zone and tolerance zone(s) are contained within
the sensing zone. The zone of limited detection capability is located between the optical window of the sensing
device and the detection zone.
3.4208
tolerance zone
zone outside of and adjacent to the (configured) detection zone within which the specified test
piece may not be detected
3.4209
vision-based protective device
VBPD
ESPE using an imaging sensor, operating in the visible and near infrared light spectrum to
detect an object in a defined field of view
Note 1 to entry: This note applies to the French language only.
3.4210
vision-based protective device using passive reference pattern techniques
VBPDPP
VBPD using a single imaging device and active illumination viewing on a passive reference
pattern as background
Note 1 to entry: The various parts of a VBPDPP and their relationship to the viewed scene is shown in Figure 1.
Note 2 to entry: This note applies to the French language only.
Figure 1 – Image planes in VBPDPP
3.4211
zone with limited detection capability
volume between the detection zone and the optical window(s) of the sensing device which does
not achieve the stated detection capability
Note 1 to entry: The dimensions and appropriate information for use of the zone with limited detection capability
are provided by the supplier.
4 Functional, design and environmental requirements
This clause of IEC 61496-1:2020 is applicable except as follows:
4.1 Functional requirements
4.1.2 Sensing function
Replacement:
4.1.2.1 General
The detection zone shall begin at the border of the zone of limited detection capability and end
at the passive reference pattern (see Figure 2).
NOTE It is possible that only parts of the passive reference pattern are used to define the detection zone.
Object(s) in the zone of limited detection capability shall not reduce the detection capability
within the detection zone. Any reduction of the detection capability shall be detected and the
VBPDPP shall go to lock-out condition (see 4.2.2.4).
– 10 – IEC TS 61496-4-2:2022 © IEC 2022
Figure 2 – Side view of VBPDPP using a passive reference pattern
4.1.2.2 Additional functional requirements
The sensing function shall be effective over the specified detection zone. No adjustment of the
detection zone or detection capability shall be possible without the use of a security measure
(e.g. key, key-word or tool).
The sensing device of a VBPDPP shall respond by giving (an) appropriate output signal(s) when
a test piece is placed anywhere within the detection zone either static or moving.
The supplier shall specify the limits of detection capability. The supplier shall take into account
worst case scenario including, for example, signal-to-noise ratio, light intensity in the image on
the sensor plane, contrast in the image on the sensor plane, position of the image on the sensor,
considering all influences listed in this document.
4.1.2.3 Optical performance
The VBPDPP shall be designed and constructed to
• limit the possibility of malfunction during exposure to extraneous radiation in the range of
400 nm to 1 500 nm;
• limit the effects of environmental influences (temperature, vibration and bumps, dust,
moisture, ambient light, extraneous reflections, changing illumination, shadows, background
reflectivity);
• limit the misalignment at which normal operation is possible.
4.1.3 Types of ESPE
Replacement:
In this document, only a type 3 ESPE is considered. It is the responsibility of the machine
supplier and/or the user to specify which type is required for a particular application.
The type 3 ESPE shall fulfil the fault detection requirements of 4.2.2.4 of this document. In
normal operation, the output circuit of each of at least two output signal switching devices
(OSSDs) shall go to the OFF-state when the sensing device is actuated, or when the power is
removed from the ESPE.
When a single safety-related data interface is used to perform the functions of the OSSD(s),
then the data interface and associated safety-related communication interface shall meet the
requirements of 4.2.4.4 of IEC 61496-1:2020. In this case, a single safety-related data interface
can substitute for two OSSDs in a type 3 ESPE.
Addition:
4.1.6 Zone with limited detection capability
A zone between the optical window and the beginning of the detection zone is referred to as a
zone with limited detection capability. In order to ensure no hazard can arise in a particular
application due to the presence of this zone between the optical window and the detection zone,
its dimensions and appropriate information for use shall be provided by the supplier.
4.2 Design requirements
4.2.2 Fault detection requirements
4.2.2.2 Particular requirements for a type 1 ESPE
This subclause of IEC 61496-1:2020 is not applicable.
4.2.2.3 Particular requirements for a type 2 ESPE
This subclause of IEC 61496-1:2020 is not applicable.
4.2.2.4 Particular requirements for a type 3 ESPE
Addition:
NOTE Examples of deterioration of the VBPDPP detection capability include:
– increase of the minimum detectable object size;
– Increase in the minimum detectable contrast.
4.2.2.5 Particular requirements for a type 4 ESPE
This subclause of IEC 61496-1:2020 is not applicable.
NOTE Type 4 is not considered in this document. Additional definitions, requirements and test procedures would
be necessary.
– 12 – IEC TS 61496-4-2:2022 © IEC 2022
4.2.12 Integrity of the ESPE detection capability
Replacement:
4.2.12.1 General
The design of the VBPDPP shall ensure that the detection capability is not decreased below
the limits specified by the supplier and in this document by any of, but not limited to, the
following:
a) at the minimum contrast between an object and reference pattern on the evaluation images;
NOTE Minimum contrast on the evaluation image can be achieved by low or high contrast in the scene.
b) the position of the object within the detection zone
c) the number of objects;
d) the size of objects;
e) auto-adjustment, for example the following:
1) auto-focus
2) gain control
3) orientation
4) sample rate
5) shutter time
6) aperture stops
7) focal length
f) properties/limitations of imaging sensor, for example the following:
1) signal noise (e.g. fixed pattern noise; dark noise)
2) dynamic range
3) sensitivity
4) micro lenses
5) gain settings
6) cold and hot pixels
7) dark current
8) change of characteristics, e.g. wavelength dependent sensitivity, filter
9) photo response non-uniformity
g) accuracy of object position in images, accuracy and stability of calibration;
h) at the limits of alignment and/or adjustment;
i) ageing of components;
j) performance and limitations of the optical components;
k) component tolerances;
l) changing of internal and external references to guarantee the detection capability;
m) environmental conditions specified in 4.3.
If a single fault (as specified in Annex B of IEC 61496-1:2020), which under normal operating
conditions (see 5.1.2.1 of IEC 61496-1:2020) would not result in a loss of VBPDPP detection
capability but, when occurring with a combination of the conditions specified above, would result
in such a loss, that fault, together with that combination of conditions (as determined to be
relevant during the analysis of the design) shall be considered as a single fault and the VBPDPP
shall respond to such a single fault as required in 4.2.2.4.
The VBPDPP shall not fail to danger if a reflective object (for example, reflective clothes) is
placed at any position in the detection zone.
The relationship of the minimum detectable object size and the size of the elements of the
passive reference pattern shall be sufficient to ensure the integrity of the detection capability
(e.g. object size is three or more times the size of the pattern element).
4.2.12.2 Detection zone
The supplier shall specify the size, shape and other relevant parameters of the detection
zone(s). The supplier shall define values in the range up to 200 mm as the minimum detectable
object size of the VBPDPP. The minimum detectable object size may be distance dependent.
All points on a path projected from any point on the border of the detection zone to the imaging
sensor of the VBPDPP shall be within the detection zone or the zone with limited detection
capability (see 4.1.6).
4.2.12.3 Response time
Objects of the minimum detectable size that are either stationary or moving within the detection
zone at any speed up to 1,6 m/s shall be detected by the ESPE within the specified response
time. The supplier shall specify the maximum response time. The supplier shall take into
account worst case conditions including, for example, frame rate, evaluation time, minimum
diameter of the test piece, maximum speed of the test piece and number of objects in the
detection zone as well as environmental influences. Where the supplier states that a VBPDPP
can be used to detect objects moving at speeds greater than 1,6 m/s, the requirements shall
be met at any speed up to and including the stated maximum speed(s).
4.2.12.4 Tolerance zone(s)
Where a tolerance zone is necessary, the supplier shall specify the tolerance zone(s).
The supplier shall take into account worst-case conditions including for example, signal-to-
noise ratio S/N.
NOTE The tolerance zone depends on optical performance, systematic interferences, pixel size, resolution,
geometry of the pattern elements, etc.
4.2.12.5 Passive reference pattern(s) and object discrimination
The passive reference pattern is part of the VBPDPP. The design of the passive reference
pattern shall be made in a way that discrimination of the object from the pattern can be
achieved. The detection capability shall not be decreased below the limits specified by the
supplier by any of, but not limited to the following influences:
a) contrast between pattern elements;
b) contrast changes within pattern elements;
c) size of pattern elements and number of pattern elements used for object detection;
d) size of pixels and numbers of pixels used for object detection;
e) algorithm/routines used for object discrimination in front of passive reference pattern;
f) automatic adaption of algorithm/routines;
g) size, shape, colour, reflectivity, position and texture of object compared to passive reference
pattern;
h) resulting contrast between object and pattern elements on the imaging sensor.
– 14 – IEC TS 61496-4-2:2022 © IEC 2022
4.2.13 Test piece
Replacement:
4.2.13.1 General
The test pieces shall be provided by the supplier for use in the type tests of Clause 5. They
shall be marked with a type reference and identification of the VBPDPP with which they are
intended to be used.
The test pieces shall be opaque.
The test pieces shall have a diameter equal to the maximum specified detection capability
(minimum diameter).
Different test pieces can be required for different phases of the test procedures.
Characteristics of the test piece which shall be considered are:
– size;
– shape;
– colour;
– reflectivity;
– contrast with background;
– texture.
When defining the characteristics of the test piece, protection against camouflage (i.e. mimic
the background appearance), with the passive reference pattern shall be taken into account.
The reflectivity of the test piece shall be selected to create a worst-case condition for the
passive reference pattern discriminators. As a minimum, the following surfaces shall be
considered:
– a black surface with a coefficient of diffuse reflection of less than 5 % at the operating
wavelength of the VBPDPP;
– a white surface with a coefficient of diffuse reflection of 80 % to 90 % at the operating
wavelength of the VBPDPP;
– a retroreflective surface that complies with the requirements for separate performance retro-
reflective material of ISO 20471 or equivalent.
Where other surface characteristics are shown to be critical as result of the analysis of the
design, these characteristics shall be applied to the test piece. Test pieces of different
reflectivity may be necessary.
4.2.13.2 Cylindrical test piece
The test piece shall be cylindrical for detection capabilities up to 40 mm. The test piece shall
have a diameter equal to the maximum specified detection capability (minimum diameter) and
a length selected for ease of use.
NOTE Depending on the diameter of the cylindrical test piece, it can represent fingers, hands or wrists.
4.2.13.3 Conical test piece
The test piece shall be a truncated cone in combination with a cylinder if the VBPDPP is
intended to be used for arm detection. The test piece starts with a diameter of 40 mm increasing
up to 55 mm as a cone over a length of 180 mm and continues as a cylinder with a diameter of
55 mm to an overall length of 440 mm.
The test piece shall be a truncated cone if the VBPDPP is intended to be used for leg detection.
The test piece starts with a diameter of 50 mm increasing up to 117 mm over a length of
1 000 mm.
If the VBPDPP is intended to be used for detection of different parts of a body, the selection of
the most appropriate test pieces shall be dependent on the analysis of the design and intended
application. In some cases, all test pieces can be required.
4.2.13.4 Spherical test piece
If the VBPDPP is intended to be used for whole body detection, then the test piece shall be a
sphere with a maximum diameter of 200 mm attached to a cylinder with a maximum diameter
of 50 mm and a length selected for ease of use.
NOTE A spherical test piece with a diameter of 200 mm is intended to represent the thickness of a body.
Addition:
4.2.14 Wavelength
VBPDPPs shall operate at a wavelength within the range of 400 nm to 1 500 nm.
4.2.15 Radiation intensity
Where the VBPDPP is of the type that emits light and if the emitting element uses LED
technology, the radiation intensity generated and emitted by the VBPDPP shall meet the
requirements of exempt group in accordance to IEC 62471.
NOTE Exempt group is equal to risk group zero (IEC 62471).
Where the VBPDPP is of the type that emits light and if the emitting element uses laser
technology, the radiation intensity generated and emitted by the VBPDPP shall at no time
exceed the maximum power or energy levels for a class 1M device in accordance with 8.2 of
IEC 60825-1:2014. The marking as class 1 or class 1M laser shall be carried out as required in
5.2 of IEC 60825-1:2014.
4.2.16 Mechanical construction
When the detection capability can be decreased below the limit stated by the supplier as a
result of a change of position of its components, the fixing of those components shall not rely
solely on friction.
NOTE The use of oblong mounting holes without additional means could lead for example to a change of the position
of the detection zone under mechanical interference such as bump.
4.3 Environmental requirements
Addition:
4.3.6 Ambient light intensity
The VBPDPP shall continue in normal operation within a range of illumination on the passive
reference pattern, from 100 lx to 1 500 lx. If the supplier specifies background characteristics
with lower limits those shall be used. The tests shall be performed at those limits. Outside this
range or these limits the VBPDPP shall not fail to danger.
4.3.7 Pollution interference
4.3.7.1 Effects on optical window
Pollution on the optical window shall not lead to a failure to danger.
– 16 – IEC TS 61496-4-2:2022 © IEC 2022
Pollution resulting in a complete loss of the stated VBPDPP detection capability shall cause the
OSSDs to go to the OFF-state within the specified response time.
Pollution resulting in a deterioration of the stated VBPDPP detection capability shall cause the
OSSDs to go to the OFF-state within a time period of 5 s following the occurrence of the pollution
interference.
4.3.7.2 Effects in the detection zone
Pollution within the detection zone or the zone with limited detection capability shall not lead to
a failure to danger.
Pollution resulting in a complete loss of the stated VBPDPP detection capability shall cause the
OSSDs to go to the OFF-state within the specified response time.
Pollution resulting in a deterioration of the stated VBPDPP detection capability shall cause the
OSSDs to go to the OFF-state within a time period of 5 s following the occurrence of the pollution
interference.
4.3.8 Changes of passive reference pattern
Changes of the passive reference pattern caused by, for example, fading, ageing, mechanical
effects or contamination shall not lead to a failure to danger.
4.3.9 Manual interference
The following conditions shall not lead to a failure to danger:
– covering the optical window of the housing of the VBPDPP or other parts (if applicable);
– placing objects within the zone of limited detection capability;
– moving the passive reference pattern (except if the pattern is required to be permanently
fixed) in any direction.
If the manual interference would result in a failure to danger condition then the VBPDPP shall
respond by giving (an) appropriate output signal(s) within 5 s. The appropriate output signal(s)
shall remain until the manual interference is removed.
4.3.10 Optical occlusion (eclipsed by small object)
The VBPDPP detection capability shall be maintained if moving or static objects or parts of a
machine which are smaller than the detection capability are in the detection zone or the zone
with limited detection capability, which can block the view of the object which shall be detected.
If the detection capability can not be maintained the OSSDs shall go to the OFF-state and shall
remain in the OFF-state if the object is removed. This shall be verified by analysis and by a test
according to 5.4.9.
NOTE Software filtering algorithms are sometimes provided to disregard small objects, for example, to increase the
reliability of operation.
4.3.11 Drift or ageing of components
Drift or ageing of components that would reduce the detection capability below the stated value
shall not cause a failure to danger of the ESPE, shall be detected within 5 s and shall lead to a
lock-out condition.
If a reference object is used for monitoring ageing and drift of components, variations in the
properties of the reference object (for example, reflectance) shall not cause a failure to danger
of the ESPE. If a reference object is used to monitor ageing and drift of components, it shall be
considered to be part of the VBPDPP and shall be provided by the supplier of the VBPDPP.
5 Testing
This clause of IEC 61496-1:2020 is applicable except as follows:
5.1 General
5.1.1 Type tests
5.1.1.1 Test samples
Addition:
As a result of the analysis of the design and optical performance of the VBPDPP the test plan
shall be established considering the test conditions and parameters outlined in this document.
The minimum test conditions shall be as specified in this document or by the supplier, whichever
is more stringent. Unless otherwise stated, the tests shall be done with the minimum detection
zone positioned as specified in Table 421.
In the following tests, it shall be verified that when the OSSDs go to the OFF-state, they remain
in the OFF-state while the test piece is present in the detection zone.
5.2 Functional tests
5.2.1 Sensing function
Addition:
5.2.1.1 General
The sensing function and the integrity of the detection capability shall be tested as specified,
taking into account the following:
– Tests shall be performed with the test piece close to the passive reference pattern, close to
the zone of limited detection and close to the tolerance zone(s). Tests at other locations
may be required depending on analysis of the design and worst-case considerations.
– All tests shall be performed with the test piece axis parallel to the passive reference pattern.
Tests at other angles of inclinations may be required depending on analysis of the design
and worst-case considerations.
– During the tests, the fixture holding the test piece should not be visible to the sensor (as
much as practical).
– The tests shall verify that the specified test pieces are detected when the test piece is placed
entirely inside the stated detection zone(s) as far as the stated detection capability.
– The tests shall verify that the specified test pieces are continuously detected when the test
piece is moving into or within the detection zone at any speed from 0 m/s to 1,6 m/s. Where
the supplier states that objects can be detected moving at higher speeds, the requirements
shall be met at all speeds up to the stated maximum speeds.
– The number, selection and conditions of the individual tests shall be such as to verify the
requirements of 4.2.12.
It shall be verified that the sensing device is continuously actuated and, where appropriate, that
the OSSDs go to the OFF-state as described below, taking into account the operating principle
of the VBPDPP and, in particular, the techniques used to provide tolerance to environmental
interference.
An overview of the minimum tests required for verification of the detection capability is shown
in Table 421.
– 18 – IEC TS 61496-4-2:2022 © IEC 2022
Table 421 – Verification of detection capability requirements (see also 4.2.12)
Maximum operating
Minimum operating distance
distance from sensing
from sensing device to
device to passive
b
passive reference pattern
reference pattern
Test related
a
Sub-clause
Conditions
to
Test piece Test piece Test piece Test piece on
at minimum on passive at minimum passive
detection reference detection reference
c c c c
distance pattern distance pattern
5.2.1.1 Sensing Applicable test X X X X
function piece (see 4.2.13)
Speed between
0 m/s and 1,6 m/s
d
5.2.1.3 Endurance See 5.2.1.3 See 5.2.1.3
Test
e
5.4.2 of Ambient X
50 °C or maximum
IEC 61496- temperature
5.4.2 of IEC 61496-
1:2020 variation
1:2020 applies.
5.4.2 of Ambient 0° or minimum, X
f
IEC 61496- temperature
non-condensing
1:2020 variation
5.4.2 of IEC 61496-
1:2020 applies.
5.4.2 of Humidity 5.4.2 applies. X
IEC 61496-
1:2020
5.4.3 of Electrical 4.3.2, 5.2.3.1 and X
IEC 61496- disturbances 5.4.3 of IEC 61496-
1:2020 1:2020 apply.
5.4.4.1 Vibration 5.4.4.1 applies X
5.4.4.2 Shock 5.4.4.2 applies X
5.4.6 Light See Table 422
interference
5.4.7 Pollution on See 5.4.7 See 5.4.7 See 5.4.7 See 5.4.7
the surface of
the optical
window
(4.3.7.1)
5.4.7 Pollution in See 5.4.7 See 5.4.7 See 5.4.7 See 5.4.7
the detection
zone (4.3.7.2)
5.4.8 Changes of Homogenous See 5.4.8 See 5.4.8 See 5.4.8 See 5.4.8
passive change for ageing
reference
Local effects for
pattern
damage
5.4.9 Manual Based on VBPDPP See 5.4.9 See 5.4.9 See 5.4.9 See 5.4.9
interference specific analysis
5.4.10 Optical See 5.4.10 X (test X
occlusion piece
(test piece
position
position
5.4.10)
5.4.10)
a
Specific tests may be required depending on an analysis of the design.
b
For ease of use, testing at 0,5m may be performed if the minimum operating distance stated by the supplier is
below this distance. Tests at other and/or additional operating distance(s) may be required based on analysis.
c
Determining the location of the test piece within the detection zone may require analysis of the system to ensure
that a worst case test is performed (e.g. when the sensor axis is not perpendicular to the passive reference
pattern).
d
Effects of ageing of components, undetected faults of components and pollution on the surface of the optical
window of the housing should be addressed within the endurance test, otherwise additional tests may be
necessary.
e
VBPDPP in test chamber – open test chamber – start test within 1 min.
f
VBPDPP in test chamber – open test chamber – test without condensation
5.2.1.2 Integrity of the VBPDPP detection capability
It shall be verified that the VBPDPP detection capability is continuously maintained or the ESPE
does not fail to danger by systematic analysi
...
IEC TS 61496-4-2 ®
Edition 2.0 2022-09
REDLINE VERSION
TECHNICAL
SPECIFICATION
colour
inside
Safety of machinery – Electro-sensitive protective equipment –
Part 4-2: Particular requirements for equipment using vision based protective
devices (VBPD) – Additional requirements when using reference pattern
techniques (VBPDPP)
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IEC TS 61496-4-2 ®
Edition 2.0 2022-09
REDLINE VERSION
TECHNICAL
SPECIFICATION
colour
inside
Safety of machinery – Electro-sensitive protective equipment –
Part 4-2: Particular requirements for equipment using vision based protective
devices (VBPD) – Additional requirements when using reference pattern
techniques (VBPDPP)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.110; 29.260.99 ISBN 978-2-8322-5727-2
– 2 – IEC TS 61496-4-2:2022 RLV © IEC 2022
CONTENTS
FOREWORD . 3
INTRODUCTION . 2
1 Scope . 7
2 Normative references . 8
3 Terms and definitions . 8
4 Functional, design and environmental requirements . 10
5 Testing . 20
6 Marking for identification and for safe use . 34
7 Accompanying documents . 34
Annex A (normative) Optional functions of the ESPE . 35
Annex B (normative) Catalogue of single faults affecting the electrical equipment of
the ESPE, to be applied as specified in 5.3 . 38
Annex AA (informative) The positioning of VBPD in respect of parts of the human body . 39
Bibliography . 46
Figure 1 – Image planes in VBPDPP . 10
Figure 2 – Side view of VBPDPP using a passive reference pattern . 12
Figure 3 – Light intensity measurement setup for indirect light tests . 30
Figure 4 – Light intensity measurement setup for direct light tests . 32
Figure AA.1 – Minimum distance S – Example 1 . 42
Figure AA.2 – Overall minimum distance S without tolerance zone – Example 1 . 42
o
Figure AA.3 – Overall minimum distance S including tolerance zone – Example 1 . 43
o
Figure AA.4 – Minimum distance S – Example 2 . 44
Figure AA.5 – Overall minimum distance S without tolerance zone – Example 2 . 45
o
Figure AA.6 – Overall minimum distance S including tolerance zone – Example 2 . 45
o
Table 1 421 – Verification of detection capability requirements (see also 4.2.12) . 21
Table 2 422 – Overview of light interference tests . 25
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SAFETY OF MACHINERY –
ELECTRO-SENSITIVE PROTECTIVE EQUIPMENT –
Part 4-2: Particular requirements for equipment
using vision based protective devices (VBPD) –
Additional requirements when using reference
pattern techniques (VBPDPP)
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
This redline version of the official IEC Standard allows the user to identify the changes made to
the previous edition IEC TS 61496-4-2:2014. A vertical bar appears in the margin wherever a
change has been made. Additions are in green text, deletions are in strikethrough red text.
– 4 – IEC TS 61496-4-2:2022 RLV © IEC 2022
IEC TS 61496-4-2 has been prepared by IEC technical committee TC 44: Safety of machinery
– Electrotechnical aspects. It is a Technical Specification.
This second edition cancels and replaces the first edition published in 2014. This edition
constitutes a technical revision.
This edition includes the following technical changes with respect to the previous edition:
a) Some requirement clauses and test procedures have been adapted or removed because
they have been consolidated in IEC 61496-1:2020 (e.g. 5.4.6.2 of IEC 61496-1:2020 Light
sources or Clause A.9)
The text of this document is based on the following documents:
Draft Report on voting
44/933/DTS 44/955A/RVDTS
Full information on the voting for the approval of this document can be found in the report on
voting indicated in the above table.
The language used for the development of this document 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 www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at http://www.iec.ch/standardsdev/publications.
This document is to be used in conjunction with IEC 61496-1:2020.
This document supplements or modifies the corresponding clauses in IEC 61496-1:2020 to
specify particular requirements for the design, construction and testing of electro-sensitive
protective equipment (ESPE) for the safeguarding of machinery, employing vision based
protective devices (VBPD) using reference pattern techniques (VBPDPP) for the sensing
function.
Where a particular clause or subclause of IEC 61496-1:2020 is not mentioned in this document,
that clause or subclause applies as far as is reasonable. Where this document states "addition",
"modification" or "replacement", the relevant text of IEC 61496-1:2020 is adapted accordingly.
Clauses and subclauses which are additional to those of IEC 61496-1:2020 are numbered
sequentially, following on the last available number in IEC 61496-1:2020. Terminological entries
(in Clause 3) which are additional to those in IEC 61496-1:2020 are numbered starting from
3.4201. Additional annexes are lettered from AA onwards and additional tables are numbered
with prefix 42
A list of all parts in the IEC 61496 series, published under the general title Safety of machinery
– Electro-sensitive protective equipment, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.
– 6 – IEC TS 61496-4-2:2022 RLV © IEC 2022
INTRODUCTION
An electro-sensitive protective equipment (ESPE) is applied to machinery presenting a risk of
personal injury. It provides protection by causing the machine to revert to a safe condition before
a person can be placed in a hazardous situation.
The working group responsible for drafting this document was concerned that, due to the
complexity of the technology, there are many issues that are highly dependent on analysis and
expertise in specific test and measurement techniques. In order to provide a high level of
confidence, independent review by relevant expertise is required recommended. They
considered that if this high level of confidence could not be established these devices would
not be suitable for use in safety related applications.
SAFETY OF MACHINERY –
ELECTRO-SENSITIVE PROTECTIVE EQUIPMENT –
Part 4-2: Particular requirements for equipment
using vision based protective devices (VBPD) –
Additional requirements when using reference
pattern techniques (VBPDPP)
1 Scope
Replacement:
This document specifies requirements for the design, construction and testing of non-contact
electro-sensitive protective equipment (ESPE) designed specifically to detect persons as part
of a safety-related system, employing vision-based protective devices (VBPDs) using passive
reference patterns techniques (VBPDPP) for the sensing function. Special attention is directed
to features which ensure that an appropriate safety-related performance is achieved. An ESPE
may can include optional safety-related functions, the requirements for which are given in
Annex A of IEC 61496-1:20122020 and this document.
NOTE "Non-contact" means that physical contact is not required for sensing.
Where this document does not contain all necessary provisions, then IEC TS 62998-1 applies.
It is also possible, for those aspects not considered in this document, to use provisions from
IEC TS 62998-1 additionally.
This document does not specify the dimensions or configurations of the detection zone and its
disposition in relation to hazardous parts for any particular application, nor what constitutes a
hazardous state of any machine. It is restricted to the functioning of the ESPE and how it
interfaces with the machine.
A VBPDPP is defined as consisting of a single image-sensing device viewing on a passive
reference pattern as the background and where the detection principle is based on blocking or
partially preventing the view of the pattern. Information about the thickness, shape, surface
characteristics or location of the object is not required for detection. For multi-image sensing
devices, additional techniques, requirements and test procedures can be necessary.
• This document is limited to automatic vision-based ESPEs that do not require human
intervention for detection.
• It is limited to automatic vision-based ESPEs that detect objects entering into, or are present
in, a detection zone(s).
• It is limited to ESPEs using active illumination technique.
• Excluded from this technical specification are VBPDPPs employing radiation at wavelengths
outside the range 400 nm to 1 500 nm.
• This document does not address those aspects required for complex classification or
differentiation of the object detected.
This document is relevant for VBPDPPs having a stated detection capability up to 200 mm.
NOTE The positioning of VBPD in respect of parts of the human body is presented in Annex AA of this document.
This document does not deal with EMC emission requirements.
– 8 – IEC TS 61496-4-2:2022 RLV © IEC 2022
2 Normative references
Addition:
IEC 60825-1:20072014, Safety of laser products – Part 1: Equipment classification and
requirements
IEC 61496-1:20122020, Safety of machinery – Electro-sensitive protective equipment – Part 1:
General requirements and tests
IEC 62471:2006, Photobiological safety of lamps and lamp systems
ISO 13855:2010, Safety of machinery – Positioning of safeguards with respect to the approach
speeds of parts of the human body
ISO 20471:2013, High-visibility clothing – Test methods and requirements
3 Terms and definitions
This clause of IEC 61496-1:2020 is applicable except as follows:
Replacement:
3.3
detection capability
ability to detect the specified test pieces (see 4.2.13) in the specified detection zone
Note 1 to entry: Detection capability is generally measured by the size of object that can be detected. An increase
in detection capability means that a smaller object can be detected.
[SOURCE: IEC 61496-1:20122020, 3.3, modified – The text has been changed to make it more
relevant to vision based sensors and Note 1 has been added]
Additions:
3.4201
image
snap shot representation of the scene in different planes of the VBPDPP in the form of a two
dimensional matrix
3.4202
imaging sensor
optoelectronic device which produces electrical signals representing the characteristics of an
image
3.4203
passive reference pattern
static (i.e. fixed location and not changing) regular (periodic) combination of pattern elements
on a background that covers at least the detection zone and the tolerance zone – blocking the
view of part of the pattern causes detection
Note 1 to entry: Regularity of the pattern refers only to the physical pattern and not to the image of the pattern as
seen by the imaging sensor.
3.4204
pattern element
local part of the passive reference pattern
EXAMPLE Black and white checker board – one black square or one white square.
3.4205
pixel,
smallest light sensitive element of an imaging sensor array
3.4206
pixel,
area of the smallest element that can be distinguished from its neighbouring elements
3.4207
sensing zone
three-dimensional volume defined by the field of view of the image sensor and with the apex at
the optical window of the sensor sensing device
Note 1 to entry: The volume could be in the shape of a pyramid or cone.
Note 2 to entry: A zone of limited detection capability, a detection zone and tolerance zone(s) are contained within
the sensing zone. The zone of limited detection capability is located between the optical window of the sensor sensing
device and the detection zone.
3.4208
tolerance zone
zone outside of and adjacent to the (configured) detection zone within which the specified test
piece may not be detected
3.4209
vision-based protective device
VBPD
ESPE using an imaging sensor and active illumination, operating in the visible and near infrared
light spectrum to detect an object in a defined field of view
Note 1 to entry: This note applies to the French language only.
3.4210
vision-based protective device using passive reference pattern techniques
VBPDPP
VBPD using a single imaging device and active illumination viewing on a passive reference
pattern as background
Note 1 to entry: The various parts of a VBPDPP and their relationship to the viewed scene is shown in Figure 1.
Note 2 to entry: This note applies to the French language only.
– 10 – IEC TS 61496-4-2:2022 RLV © IEC 2022
Objective / lens
Imaging sensor
Data pre-
processing –
if applicable
Evaluation Image
reference pattern = scene Image in
sensor plane
IEC 1464/14
Figure 1 – Image planes in VBPDPP
3.4211
zone with limited detection capability
volume between the detection zone and the optical window(s) of the sensing device which does
not achieve the stated detection capability
Note 1 to entry: The dimensions and appropriate information for use of the zone with limited detection capability
are provided by the supplier.
4 Functional, design and environmental requirements
This clause of IEC 61496-1:2020 is applicable except as follows:
4.1 Functional requirements
4.1.1 Normal operation
This subclause of Part 1 is applicable.
4.1.2 Sensing function
Replacement:
4.1.2.1 General
The detection zone shall begin at the border of the zone of limited detection capability and end
at the passive reference pattern (see Figure 2).
NOTE It is possible that only parts of the passive reference pattern are used to define the detection zone.
Object(s) in the zone of limited detection capability shall not reduce the detection capability
within the detection zone. Any reduction of the detection capability shall be detected and the
VBPDPP shall go to lock-out condition (see 4.2.2.4).
sensing device
Zone with limited
detection capability
Optical
window
Tolerance zone
Tolerance zone
Background
(reference pattern)
Detection zone
IEC 1465/14
Operating distance
– 12 – IEC TS 61496-4-2:2022 RLV © IEC 2022
Figure 2 – Side view of VBPDPP using a passive reference pattern
4.1.2.2 Additional functional requirements
The sensing function shall be effective over the specified detection zone. No adjustment of the
detection zone or detection capability shall be possible without the use of a security measure
(e.g. key, key-word or tool).
The sensing device of a VBPDPP shall respond by giving (an) appropriate output signal(s) when
a test piece is placed anywhere within the detection zone either static or moving.
The supplier shall specify the limits of detection capability. The supplier shall take into account
worst case scenario including, for example, signal-to-noise ratio, light intensity in the image on
the sensor plane, contrast in the image on the sensor plane, position of the image on the sensor,
considering all influences listed in this document.
4.1.2.3 Optical performance
The VBPDPP shall be designed and constructed to
• limit the possibility of malfunction during exposure to extraneous radiation in the range of
400 nm to 1 500 nm;
• limit the effects of environmental influences (temperature, vibration and bumps, dust,
moisture, ambient light, extraneous reflections, changing illumination, shadows, background
reflectivity);
• limit the misalignment at which normal operation is possible.
4.1.3 Types of ESPE
Replacement:
In this document, only a type 3 ESPE is considered. It is the responsibility of the machine
supplier and/or the user to determine if this type is suitable specify which type is required for a
particular application.
The type 3 ESPE shall fulfil the fault detection requirements of 4.2.2.4 of this document. In
normal operation, the output circuit of each of at least two output signal switching devices
(OSSDs) shall go to the OFF-state when the sensing device is actuated, or when the power is
removed from the device ESPE.
When a single safety-related data interface is used to perform the functions of the OSSD(s),
then the data interface and associated safety-related communication interface shall meet the
requirements of 4.2.4.4 of IEC 61496-1:2020. In this case, a single safety-related data interface
can substitute for two OSSDs in a type 3 ESPE.
4.1.4 Types and required safety performance
This subclause of Part 1 is applicable.
4.1.5 Required PL or SIL and corresponding ESPE type
r
This subclause of Part 1 is applicable.
New functional requirement Addition:
4.1.6 Zone with limited detection capability
A zone between the optical window and the beginning of the detection zone is referred to as a
zone with limited detection capability. In order to ensure no hazard can arise in a particular
application due to the presence of this zone between the optical window and the detection zone,
its dimensions and appropriate information for use shall be provided by the supplier.
4.2 Design requirements
4.2.2 Fault detection requirements
4.2.2.2 Particular requirements for a type 1 ESPE
This subclause of IEC 61496-1:2020 is not applicable.
4.2.2.3 Particular requirements for a type 2 ESPE
This subclause of IEC 61496-1:2020 is not applicable.
4.2.2.4 Particular requirements for a type 3 ESPE
Replacement:
A single fault in the sensing device resulting in a complete loss of the stated VBPDPP detection
capability shall cause the ESPE to go to a lock-out condition within the specified response time.
A single fault resulting in a deterioration of the stated VBPDPP detection capability shall cause
the ESPE to go to a lock-out condition within a time period of 5 seconds following the occurrence
of that fault.
Addition:
– 14 – IEC TS 61496-4-2:2022 RLV © IEC 2022
NOTE Examples of deterioration of the VBPDPP detection capability include:
– increase of the minimum detectable object size;
– Increase in the minimum detectable contrast.
A single fault resulting in an increase in response time beyond the specified value or preventing
at least one OSSD going to the OFF-state shall cause the ESPE to go to a lockout condition
immediately, i.e. within the response time, or immediately upon any of the following demand
events where fault detection requires a change in state:
− on actuation of the sensing function;
− on switch off/on;
− on reset of the start interlock or the restart interlock, if available (see Clauses A.5 and A.6
of IEC 61496-1:2012).
It shall not be possible for the ESPE to achieve a reset from a lock-out condition, for example,
by interruption and restoration of the mains power supply or by any other means, when the fault
which initiated the lock-out condition is still present.
In cases where a single fault which does not cause a failure to danger of the ESPE is not
detected, the occurrence of one additional fault shall not cause a failure to danger.
For verification of this requirement, see 5.3.4.
4.2.2.5 Particular requirements for a type 4 ESPE
This subclause of IEC 61496-1:2020 is not applicable.
NOTE Type 4 is not considered in this document. Additional definitions, requirements and test procedures would
be necessary.
Additional design requirements:
4.2.12 Integrity of the VBPDPP ESPE detection capability
Replacement:
4.2.12.1 General
The design of the VBPDPP shall ensure that the detection capability is not degraded decreased
below the limits specified by the supplier and in this document by any of, but not limited to, the
following:
a) at the minimum contrast between an object and reference pattern on the evaluation images;
NOTE Minimum contrast on the evaluation image can be achieved by low or high contrast in the scene.
b) the position of the object within the detection zone
c) the number of objects;
d) the size of objects;
e) auto-adjustment, for example the following:
1) auto-focus
2) gain control
3) orientation
4) sample rate
5) shutter time
6) aperture stops
7) focal length
f) properties/limitations of imaging sensor, for example the following:
1) signal noise (e.g. fixed pattern noise; dark noise)
2) dynamic range
3) sensitivity
4) micro lenses
5) gain settings
6) cold and hot pixels
7) dark current
8) change of characteristics, e.g. wavelength dependent sensitivity, filter
9) photo response non-uniformity
g) accuracy of object position in images, accuracy and stability of calibration;
h) at the limits of alignment and/or adjustment;
i) ageing of components;
j) performance and limitations of the optical components;
k) component tolerances;
l) changing of internal and external references to guarantee the detection capability;
m) environmental conditions specified in 4.3.
If a single fault (as specified in Annex B of IEC 61496-1:20122020), which under normal
operating conditions (see 5.1.2.1 of IEC 61496-1:20122020) would not result in a loss of
VBPDPP detection capability but, when occurring with a combination of the conditions specified
above, would result in such a loss, that fault, together with that combination of conditions (as
determined to be relevant during the analysis of the design) shall be considered as a single
fault and the VBPDPP shall respond to such a single fault as required in 4.2.2.4.
The VBPDPP shall not fail to danger if a reflective object (for example, reflective clothes) is
placed at any position in the detection zone.
The relationship of the minimum detectable object size and the size of the elements of the
background passive reference pattern shall be sufficient to ensure the integrity of the detection
capability (e.g. object size is three or more times the size of the pattern element).
4.2.12.2 Detection zone
The supplier shall specify the size, shape and other relevant parameters of the detection
zone(s). The supplier shall define values in the range up to 200 mm as the minimum detectable
object size of the VBPDPP. The minimum detectable object size may be distance dependent.
All points on a path projected from any point on the border of the detection zone to the imaging
sensor of the VBPDPP shall be within the detection zone or the zone with limited detection
capability (see 4.1.46).
4.2.12.3 Response time
Objects of the minimum detectable size that are either stationary or moving within the detection
zone at any speed up to 1,6 m/s shall be detected by the ESPE within the specified response
time. The supplier shall specify the maximum response time. The supplier shall take into
account worst case conditions including, for example, frame rate, evaluation time, minimum
diameter of the test piece, maximum speed of the test piece and number of objects in the
detection zone as well as environmental influences. Where the supplier states that a VBPDPP
can be used to detect objects moving at speeds greater than 1,6 m/s, the requirements shall
be met at any speed up to and including the stated maximum speed(s).
– 16 – IEC TS 61496-4-2:2022 RLV © IEC 2022
4.2.12.4 Tolerance zone(s)
Where a tolerance zone is necessary, the supplier shall specify the tolerance zone(s).
The supplier shall take into account worst-case conditions including for example, signal-to-
noise ratio S/N.
NOTE The tolerance zone depends on optical performance, systematic interferences, pixel size, resolution,
geometry of the pattern elements, etc.
4.2.12.5 Passive reference pattern(s) and object discrimination
The passive reference pattern is part of the VBPDPP. The design of the passive reference
pattern shall be made in a way that discrimination of the object from the pattern can be
achieved. The detection capability shall not be decreased below the limits specified by the
supplier by any of, but not limited to the following influences:
a) contrast between pattern elements;
b) contrast changes within pattern elements;
c) size of pattern elements and number of pattern elements used for object detection;
d) size of pixels and numbers of pixels used for object detection;
e) algorithm/routines used for object discrimination in front of passive reference pattern;
f) automatical adaption of algorithm/routines;
g) size, shape, colour, reflectivity, position and texture of object compared to passive reference
pattern;
h) resulting contrast between object and pattern elements on the imaging sensor.
4.2.13 Test pieces for type testing
Replacement:
4.2.13.1 General
The test pieces shall be provided by the supplier for use in the type tests of Clause 5. They
shall be marked with a type reference and identification of the VBPDPP with which they are
intended to be used.
The test pieces shall be opaque.
The test pieces shall have a diameter equal to the maximum specified detection capability
(minimum diameter).
Different test pieces can be required for different phases of the test procedures.
Characteristics of the test piece which shall be considered are:
– size;
– shape;
– colour;
– reflectivity;
– contrast with background;
– texture.
When defining the characteristics of the test piece, protection against camouflage (i.e. mimic
the background appearance), with the passive reference pattern shall be taken into account.
The reflectivity of the test piece shall be selected to create a worst-case condition for the
passive reference pattern discriminators. As a minimum, the following surfaces shall be
considered:
– a black surface with a coefficient of diffuse reflectance value below reflection of less than
5 % at the operating wavelength of the VBPDPP;
– a white surface with a coefficient of diffuse reflectance value in the range reflection of 80 %
to 90 % at the operating wavelength of the VBPDPP;
– a retroreflective surface that complies with the requirements for separate performance retro-
reflective material of ISO 20471 or equivalent.
Where other surface characteristics are shown to be critical as result of the analysis of the
design, these characteristics shall be applied to the test piece. Test pieces of different
reflectivity may be necessary.
4.2.13.2 Spherical test piece
If the VBPDPP is intended to be used for whole body detection, then the test piece shall be a
sphere with a maximum diameter of 200 mm attached to a cylinder with a maximum diameter
of 50 mm and a length selected for ease of use.
NOTE A spherical test piece with a diameter of 200 mm is intended to represent the thickness of a body.
4.2.13.32 Cylindrical test piece
The test piece shall be cylindrical for detection capabilities up to 40 mm. The test piece shall
have a diameter equal to the maximum specified detection capability (minimum diameter) and
a length selected for ease of use.
NOTE Depending on the diameter of the cylindrical test piece, it can represent fingers, hands or wrists.
4.2.13.43 Conical test piece
The test piece shall be a truncated cone in combination with a cylinder if the VBPDPP is
intended to be used for arm detection. The test piece starts with a diameter of 40 mm increasing
up to 55 mm as a cone over a length of 180 mm and continues as a cylinder with a diameter of
55 mm to an overall length of 440 mm.
The test piece shall be a truncated cone if the VBPDPP is intended to be used for leg detection.
The test piece starts with a diameter of 50 mm increasing up to 117 mm over a length of
1 000 mm.
If the VBPDPP is intended to be used for detection of different parts of a body, the selection of
the most appropriate test pieces shall be dependent on the analysis of the design and intended
application. In some cases, all test pieces can be required.
4.2.13.4 Spherical test piece
If the VBPDPP is intended to be used for whole body detection, then the test piece shall be a
sphere with a maximum diameter of 200 mm attached to a cylinder with a maximum diameter
of 50 mm and a length selected for ease of use.
NOTE A spherical test piece with a diameter of 200 mm is intended to represent the thickness of a body.
Addition:
4.2.14 Wavelength
VBPDPPs shall operate at a wavelength within the range of 400 nm to 1 500 nm.
– 18 – IEC TS 61496-4-2:2022 RLV © IEC 2022
4.2.15 Radiation intensity
Where the VBPDPP is of the type that emits light and if the emitting device element uses LED
technology, the radiation intensity generated and emitted by the VBPDPP shall meet the
requirements of exempt group in accordance to IEC 62471:2006.
NOTE Exempt group is equal to risk group zero (IEC 62471:2006).
Where the VBPDPP is of the type that emits light and if the emitting device element uses laser
technology, the radiation intensity generated and emitted by the VBPDPP shall at no time
exceed the maximum power or energy levels for a class 1M device in accordance with 8.2 of
IEC 60825-1:20072014. The marking as class 1 or class 1M laser shall be carried out as
required in 5.2 of IEC 60825-1:2014.
4.2.16 Mechanical construction
When the detection capability can be decreased below the limit stated by the supplier as a
result of a change of position of its components, the fixing of those components shall not rely
solely on friction.
NOTE The use of oblong mounting holes without additional means could lead for example to a change of the position
of the detection zone under mechanical interference such as bump.
4.3 Environmental requirements
4.3.1 Ambient air temperature range and humidity
Addition:
The ESPE shall not fail to danger when subjected to a rapid change of temperature and humidity
leading to condensation on the optical window.
This requirement is verified by the condensing test of 5.4.2.
Additional environmental requirements:
4.3.56 Ambient light intensity
The VBPDPP shall continue in normal operation within a range of illumination on the passive
reference pattern, from 100 lx to 1 500 lx. If the supplier specifies background characteristics
with lower limits those shall be used. The tests shall be performed at those limits. Outside this
range or these limits the VBPDPP shall not fail to danger.
4.3.6 Light interference
The VBPDPP shall continue in normal operation when subjected to the following:
– incandescent light;
– flashing beacons;
– fluorescent lights operated with high-frequency electronic and line power supply.
The VBPDPP shall not fail to danger when subjected to
– incandescent light;
– stroboscopic light;
– high-intensity fluorescent lights operated with high-frequency electronic and line power
supply;
– laser beam;
– VBPDPP of identical design.
These requirements are verified by the tests of 5.4.6.
The supplier shall inform the user of potential problems not covered by the requirements of this
technical specification.
Based on the technologies and algorithms used as well as the analysis of 5.2.9, additional tests
may be necessary.
4.3.7 Pollution interference
4.3.7.1 Effects on optical window
Pollution on the optical window shall not lead to a failure to danger.
Pollution resulting in a complete loss of the stated VBPDPP detection capability shall cause the
ESPE to go to a lock-out condition OSSDs to go to the OFF-state within the specified response
time.
Pollution resulting in a deterioration of the stated VBPDPP detection capability shall cause the
ESPE to go to a lock-out condition OSSDs to go to the OFF-state within a time period of 5 s
following the occurrence of the pollution interference.
4.3.7.2 Effects in the detection zone
Pollution within the detection zone or the zone with limited detection capability shall not lead to
a failure to danger.
Pollution resulting in a complete loss of the stated VBPDPP detection capability shall cause the
ESPE to go to a lock-out condition OSSDs to go to the OFF-state within the specified response
time.
Pollution resulting in a deterioration of the stated VBPDPP detection capability shall cause the
ESPE to go to a lock-out condition OSSDs to go to the OFF-state within a time period of 5 s
following the occurrence of the pollution interference.
4.3.8 Changes of passive reference pattern
Changes of the passive reference pattern caused by, for example, fading, ageing, mechanical
effects or contamination shall not lead to a failure to danger.
4.3.9 Manual interference
The following conditions shall not lead to a failure to danger:
– covering the optical window of the housing of the VBPDPP or other parts (if applicable);
– placing objects within the zone of limited detection capability;
– moving the passive reference pattern (except if the pattern is required to be permanently
fixed) in any direction.
In such cases, If the manual interference would result in a failure to danger condition then the
VBPDPP shall respond by giving (an) appropriate output signal(s) within 5 s. The appropriate
output signal(s) shall remain until the manual interference is removed.
4.3.10 Optical occlusion (eclipsed by small object)
The VBPDPP detection capability shall be maintained if moving or static objects or parts of a
machine which are smaller than the detection capability are in the detection zone or the zone
with limited detection capability, which can block the view of the object which shall be detected.
– 20 – IEC TS 61496-4-2:2022 RLV © IEC 2022
If the detection capability can not be maintained the OSSDs shall go to the OFF-state and shall
remain in the OFF-state if the object is removed. This shall be verified by analysis and by a test
according to 5.4.9.
NOTE Software filtering algorithms are sometimes provided to disregard small objects, for example, to increase the
reliability of operation.
4.3.11 Drift or ageing of components
Drift or ageing of components that would reduce the detection capability below the stated value
shall not cause a failure to danger of the ESPE, shall be detected within 5 s and shall lead to a
lock-out condition.
If a reference object is used for monitoring ageing and drift of components, variations in the
properties of the reference object (for example, reflectance) shall not cause a failure to danger
of the ESPE. If a reference object is used to monitor ageing and drift of components, it shall be
considered to be part of the VBPDPP and shall be provided by the supplier of the VBPDPP.
5 Testing
This clause of IEC 61496-1:2020 is applicable except as follows:
5.1 General
5.1.1 Type tests
5.1.1.1 Test samples
Addition:
As a result of the analysis of the design and optical performance of the VBPDPP the test plan
shall be established considering the test conditions and parameters outlined in this document.
The minimum test conditions shall be as specified in this document or by the supplier, whichever
is more stringent. Unless otherwise stated, the tests shall be done with the minimum detection
zone positioned as specified in Table 1 Table 421.
In the following tests, it shall be verified that when the OSSDs go to the OFF-state, they remain
in the OFF-state while the test piece is present in the detection zone.
5.1.2 Test Conditions
5.1.2.1 Test environment
Addition:
Unless otherwise stated in this part of IEC 61496, the VBPDPP shall be set up for the test with
ambient light intensity of between 50 lx and 300 lx measured on the background.
The ambient light source should provide evenly distributed illumination as far as practical.
5.1.2.2 Measurement accuracy
Addition to the first paragraph:
– for light intensity measurement: ±10 %
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