IEC 61965:2000

INTERNATIONAL IEC
STANDARD
First edition
2000-09
Mechanical safety of cathode ray tubes
Sécurité mécanique des tubes cathodiques

Reference number
Numbering
As from 1 January 1997 all IEC publications are issued with a designation in the
60000 series.
Consolidated publications
Consolidated versions of some IEC publications including amendments are

available. For example, edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the
base publication, the base publication incorporating amendment 1 and the base

publication incorporating amendments 1 and 2.

Validity of this publication
The technical content of IEC publications is kept under constant review by the IEC,
thus ensuring that the content reflects current technology.
Information relating to the date of the reconfirmation of the publication is available
in the IEC catalogue.
Information on the subjects under consideration and work in progress undertaken
by the technical committee which has prepared this publication, as well as the list
of publications issued, is to be found at the following IEC sources:
• IEC web site*
• Catalogue of IEC publications
Published yearly with regular updates
(On-line catalogue)*
• IEC Bulletin
Available both at the IEC web site* and as a printed periodical
Terminology, graphical and letter symbols
For general terminology, readers are referred to IEC 60050: International
Electrotechnical Vocabulary (IEV).
For graphical symbols, and letter symbols and signs approved by the IEC for
general use, readers are referred to publications IEC 60027: Letter symbols to be
used in electrical technology, IEC 60417: Graphical symbols for use on equipment.
Index, survey and compilation of the single sheets and IEC 60617: Graphical symbols
for diagrams.
* See web site address on title page.

INTERNATIONAL IEC
STANDARD
First edition
2000-09
Mechanical safety of cathode ray tubes
Sécurité mécanique des tubes cathodiques

 IEC 2000  Copyright - all rights reserved
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– 2 – 61965 © IEC:2000(E)
CONTENTS
Page
FOREWORD . 5

INTRODUCTION .6

Clause
1 Scope. 7

2 Normative references . 7
3 Definitions . 8
4 General requirements. 9
4.1 Corrosion protection . 9
4.2 Mechanical damage . 9
4.3 Handling . 9
5 Environmental conditioning. 9
5.1 Standard atmospheric conditions for testing. 9
5.2 Preconditioning. 10
5.3 Thermal conditioning. 10
6 Sampling .10
6.1 Sampling plans . 10
6.2 Sample numbers. 10
6.3 Compliance. 10
7 Test preparation and set-up. 10
7.1 Scratch patterns . 10
7.2 Barriers. 10
7.3 Mounting. 11
7.4 Mounting position. 11
8 Testing of large CRTs. 11
8.1 Mechanical strength (ball impact test). 11
8.2 Implosion test (missile) . 12
8.3 Implosion test (thermal shock) . 13
8.4 High-energy impact test . 13
9 Testing of small CRTs . 14

9.1 Mechanical strength (ball impact test). 14
9.2 Implosion test (high ball). 15
9.3 Implosion test (thermal shock) . 15
9.4 High-energy impact test . 15
10 Marking . 16
11 Normative requirements for the use of tables 1 and 2 (prestressed banded CRTs) . 16
11.1 Sampling plan I: New construction . 17
11.2 Sampling plan II: New construction with known resin or tape . 18
11.3 Sampling plan III: Tension band and alternative tension band . 18
11.4 Sampling plan IV: Alternative construction . 19
12 Normative requirements for the use of tables 3 and 4 (bonded frame CRTs). 19
12.1 Sampling plan I: New construction . 19
12.2 Sampling plan II: Alternative construction . 20

61965 © IEC:2000(E) – 3 –
Clause Page
13 Normative requirements for the use of tables 5 and 6 (laminated CRTs). 21

13.1 Sampling plan I: New construction . 21

13.2 Sampling plan II: Alternative construction . 21

Annex A (informative) Background to the development of this standard. 37

A.1 Mechanical strength test. 38

A.2 Implosion test. 38

A.3 Small CRTs (76 mm to 160 mm diagonal). 38
A.4 Evaluation time.38
Annex B (informative) Velocity and potential force of glass particles expelled
from a CRT subjected to a ball impact – Ballistic and statistical calculations . 39
B.1 Introduction . 39
B.2 Analysis without friction . 39
B.3 Analysis with friction. 45
B.4 Potential threat. 48
B.5 Conclusions. 48
Figure 1 – Example of a test cabinet . 27
Figure 2 – Example of a ball impact test. 28
Figure 3 – Example of a 2,3 kg steel missile. 29
Figure 4 – Missile impact area on a typical CRT . 30
Figure 5 – Example of a missile impact test. 31
Figure 6 – Options for scratch patterns for implosions by the thermal shock method . 32
Figure 7 – Example of high-energy impact test set-up . 33
Figure 8a – Example of steel pin for CRTs exceeding 160 mm face diagonal
used in high-energy impact test. 34
Figure 8b – Example of steel pin for CRTs from 76 mm to 160 mm diagonal
used in high-energy impact test. 34
Figure 9a – Example of 4,5 kg weight used in high-energy impact test on CRTs
exceeding 160 mm diagonal . 35

Figure 9b – Example of 0,45 kg weight used in high-energy impact test on CRTs
from 76 mm to 160 mm face diagonal. 35
Figure 10 – Example of 1,4 kg steel missile. 36
Figure B.1 – Height of the barriers and distances from the CRT face. 39
Figure B.2 – Example of the parabolic trajectory of a glass particle and the definition
of the distances. 40
Figure B.3 – Definition of the initial angle and initial velocity and the forces acting
on a particle . 41
Figure B.4 – Initial velocity required to pass over barriers at x = l (solid line)
or x = l (dashed line) as a function of the initial angle β. 43
– 4 – 61965 © IEC:2000(E)
Page
Figure B.5 – Trajectories for a glass particle for different initial angles and an initial velocity

of 4 m/s . 43

Figure B.6 – Definition of the forces acting on a particle. 45

Figure B.7 – Measurements of a typical glass particle . 46

Figure B.8 – Trajectory of a glass particle with an initial velocity of 2 m/s and

an initial angle of 45° without friction (dashed line) and with friction (solid line) . 47

Figure B.9 – Trajectories of a glass particle with an initial velocity of 2 m/s and an

initial angle of 45° for different values of the cross-sectional area . 48

Table 1 – Sampling and test programme for prestressed banded CRTs
exceeding 160 mm diagonal . 22
Table 2 – Sampling and test programme for prestressed banded CRTs
from 76 mm to 160 mm diagonal . 23
Table 3 – Sampling and test programme for bonded frame CRTs
exceeding 160 mm diagonal . 24
Table 4 – Sampling and test programme for bonded frame CRTs
from 76 mm to 160 mm diagonal . 24
Table 5 – Sampling and test programme for laminated CRTs exceeding 160 mm diagonal . 25
Table 6 – Sampling and test programme for laminated CRTs
from 76 mm to 160 mm diagonal . 25
Table 7 – CRT size and deflection angle ranges. 26
Table B.1 – Values of the distances . 40
Table B.2 – Upper and lower boundary values of the initial angle . 42

61965 © IEC:2000(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
MECHANICAL SAFETY OF CATHODE RAY TUBES

FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International
Organization for Standardization (ISO) in accordance with conditions determined by agreement between the
two organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61965 has been prepared by IEC technical committee 39:
Electronic tubes.
The text of this standard is based on the following documents:
FDIS Report on voting
39/252/FDIS 39/255/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.
Annexes A and B are for information only.
The committee has decided that the contents of this publication will remain unchanged until 2004.
At this date, the publication will be
 reconfirmed;
 withdrawn;
 replaced by a revised edition; or
 amended.
A bilingual version of this publication may be issued at a later date.

– 6 – 61965 © IEC:2000(E)
INTRODUCTION
This International Standard sets forth test methods and limits for cathode ray tubes (CRTs).
Hitherto, the only IEC standard for the mechanical safety of CRTs has been contained within

clause 18 of the equipment standard IEC 60065. Whereas that standard has been accepted

and used by many countries, many others have not been able to implement its requirements

because of differing local needs. This new standard aims to provide the basis for wider

acceptance and use, and reflects the current IEC policy of producing separate component

standards to which equipment standards can refer.

Many years of experience had been built up in the use of both the IEC 60065 test and the
other commonly used national alternatives. During the development of this new standard,
extensive test programmes and ballistic and statistical calculations were carried out to verify
that the requirements of the standard give protection for users of CRTs when the tubes are
mounted in the equipment for which they are intended. This was also done to ensure that the
new standard maintains the stringent requirements of both IEC 60065 and the alternative
tests in common use. These tests and calculations also confirmed
a) the acceptability of one standard ball for the mechanical strength test, and
b) the need for the implosion test where it is not always possible to induce rapid devacuation
using the ball impact test.
As the impact tests in this standard are overstress tests, only the effect of rapid devacuation
is evaluated and not subsequent relaxation of mechanical stresses in the CRT from the
implosion protection system.
61965 © IEC:2000(E) – 7 –
MECHANICAL SAFETY OF CATHODE RAY TUBES

1 Scope
This International Standard is applicable to cathode ray tubes and cathode ray tube
assemblies (hereinafter referred to as CRTs) which are intended for use as components in

apparatus and which have integral protection with respect to the effects of implosion.

These requirements apply to CRTs intended for use in apparatus including electrical and
electronic measuring and testing equipment, information technology equipment, medical
equipment, telephone equipment, television equipment and other similar electronic apparatus.
This standard is intended to apply only to those CRTs in which the face of the CRT forms part
of the enclosure for the apparatus. The test methods do not apply to CRTs which are
protected by separate safety screens.
A CRT covered by this standard is intended to be installed in an enclosure designed both to
protect the rear of the CRT against mechanical or other damage under normal conditions of
operation and to protect the user against particles expelled in a backwards direction from the
CRT face in the event of implosion.
This standard contains requirements for CRTs of 76 mm diagonal and larger that incorporate
implosion protection systems providing protection against the hazards of particles expelled
forwards beyond the face. There is no intended protection against particles expelled in other
directions.
Compliance is tested by subjecting CRTs to the test procedures and criteria which are given
in clauses 8 (large CRTs) and 9 (small CRTs) of this standard. The definitions of large and
small CRTs are given in clause 3.
NOTE This set of requirements replaces the current requirements for the mechanical safety of cathode ray tubes
(CRTs) as described in IEC 60065 (clause 18), which will be modified accordingly.
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this International Standard. For dated references, subsequent
amendments to, or revisions of, any of these publications do not apply. However, parties to

agreements based on this International Standard are encouraged to investigate the possibility
of applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of IEC
and ISO maintain registers of currently valid International Standards.
IEC 60065:1998, Audio, video and similar electronic apparatus – Safety requirements
IEC 60068-1:1988, Environmental testing – Part 1: General and guidance
Amendment 1 (1992)
IEC 60216-1, Guide for the determination of thermal endurance properties of electrical
insulating materials. Part 1: General guidelines for ageing procedures and evaluation of test
results
– 8 – 61965 © IEC:2000(E)
3 Definitions
For the purposes of this document the following definitions apply.

3.1
bonded frame
system employing a preformed metal frame that covers the periphery of the CRT rim area.

The space or void between the CRT rim and the metal frame is filled with resin or equivalent

3.2
CRT diagonal
nominal diagonal of the glass envelope at its maximum dimension (for example, mould-match
line) excluding any hardware
3.3
CRT envelope
structure consisting of a face or faceplate, funnel and neck assembly
3.4
devacuation
equalization of the pressure in a CRT relative to the ambient pressure
3.5
fracture
one or more cracks in the faceplate or funnel causing a rapid or slow devacuation of the
CRT envelope
3.6
glass particle
piece of glass that exceeds 0,025 g in weight
3.7
implosion
devacuation due to the rapid and sudden inward collapse of a CRT envelope, usually
accompanied by a loud report
3.8
laminated CRT
system that provides a separate external safety panel bonded to the face of the CRT

3.9
prestressed banded CRT
system that employs a metal tension band (located over the CRT rim area) that is tightened
by thermal shrinking, or other means, to a tensile load. The system may also include a metal
rim band located between the tension band and the CRT rim. The tension band or the rim
band or both may have an interlayer of tape, resin or the equivalent placed between the
mating parts
3.10
shaling
condition where the glassware splits into thin layers

61965 © IEC:2000(E) – 9 –
3.11
test cabinet
enclosure which is used to accommodate the CRT during tests

3.12
useful phosphor screen
a) colour CRT: the visible phosphored area of the CRT as viewed from the front

b) monochrome CRT: specified maximum useful phosphored area of the CRT

3.13
large CRT
CRT with diagonal dimension exceeding 160 mm
3.14
small CRT
rectangular CRT with a minor face dimension of at least 50 mm, a minimum diagonal
dimension of 76 mm and a maximum diagonal dimension of 160 mm; a round CRT of a
minimum diameter of 76 mm and a maximum diameter of 160 mm
3.15
common quality management system
quality management system described in documentation which is identical with systems used
in two or more plants and under one central control and management
4 General requirements
4.1 Corrosion protection
If corrosion of a metal part will contribute to a failure to meet the requirements of this
standard, then the part shall be adequately protected against corrosion.
4.2 Mechanical damage
To improve repeatability and reproducibility of test results, it should be verified that samples
submitted for test have no external visible scratching on the surface of the face plates.
4.3 Handling
Safety precautions should be addressed when handling test samples prior to, and after testing.

5 Environmental conditioning
5.1 Standard atmospheric conditions for testing
Unless otherwise specified, all tests and measurements shall be made under standard
atmospheric conditions for testing as given in 5.3 of IEC 60068-1:
– temperature: 15 °C to 35 °C;
– relative humidity: 25 % to 75 %;
– air pressure: 86 kPa to 106 kPa

– 10 – 61965 © IEC:2000(E)
5.2 Preconditioning
Before CRTs are subjected to thermal conditioning or to testing they will be allowed to stabilize

at standard atmospheric conditions for testing (see 5.1) for a minimum period of 16 h.

5.3 Thermal conditioning
Details of thermal conditioning are given in tables 1 to 6. After thermal conditioning has been

completed, the CRTs will be allowed to stabilize at standard atmospheric conditions for

testing (see 5.1) for a minimum period of 24 h.

6 Sampling
6.1 Sampling plans
Details are given in tables 1 to 6.
6.2 Sample numbers
The numbers of CRTs and the test programmes for prestressed banded CRTs are given in
tables 1 and 2, for bonded frame CRTs in tables 3 and 4 and for laminated CRTs in tables 5
and 6.
NOTE In addition to the quantities specified in the tables, additional samples shall be made available for use in
case of retest to satisfy the intent of the requirement.
6.3 Compliance
All CRTs in a test group shall comply with the test requirements for that group, except that, if
only one CRT from all the test groups does not comply with the requirements, acceptability
may be determined by subjecting a second test group to the set of tests during which
unacceptable results occurred. The construction is acceptable if all CRTs in the second test
group comply with the requirements.
7 Test preparation and set-up
7.1 Scratch patterns
As the form and depth of the scratch patterns may affect the force which is needed to obtain
implosion or devacuation of the CRT, it is recommended that the scratches be made using a
diamond- or carbide-tipped stylus, a glass cutter with a wheel of hardened steel or other

similar tools.
7.2 Barriers
Barriers as specified in the test procedures, each made of 10 mm to 20 mm thick material,
250 mm high and (2,00 ± 0,01) m long, shall be placed on the floor in front of the test
−3
cabinet at the specified locations, measured horizontally from the vertical plane of the centre
of the front surface of the CRT to the near surface of the barrier closest to the tube face. The
tolerance on the position of the barrier shall be ±10 mm, unless otherwise stated. The barriers
may be less than 2 m long provided that they extend to the walls of the test room
(see figures 2 and 5). A non-skid surface such as a blanket or rug may be placed on the floor.
NOTE A particle travelling past the plane of the front surface of the barrier shall be considered to have passed
the barrier.
61965 © IEC:2000(E) – 11 –
7.3 Mounting
The CRT shall be mounted in a test cabinet of rigid construction and of suitable dimensions

that does not permit a gap or opening wider than 6 mm around the CRT (see figure 1).

The mounting of the CRT in front of, or behind, the front panel of the test cabinet shall be in

accordance with the CRT manufacturer's specifications or intended application. When

mounting specifications are not available, the preferred mounting method shall be behind the

front panel unless design features do not allow this condition.

A hole of suitable area shall be provided at the top of the cabinet to allow access to the

funnel. This hole shall be covered during the impact test.

An opening having an area of not less than one-quarter of the area of the face of the CRT
or 0,02 m , whichever is the smaller, shall also be provided in the bottom or rear of the
cabinet for air intake in the event of an implosion.
The cabinet shall be firmly supported so as to prevent movement during the test.
7.4 Mounting position
The centre of the CRT shall be (1,00 ± 0,05) m above the floor.
8 Testing of large CRTs
8.1 Mechanical strength (ball impact test)
8.1.1 Test procedure
A solid smooth steel ball of (40 ± 1) mm diameter and mass of (260 ± 15) g, including the
hook, and a minimum C scale Rockwell hardness of 60, shall be suspended by suitable
means such as a fine wire or chain with a mass not exceeding 10 % of the mass of the ball
and the hook. It shall be allowed to fall freely as a pendulum from a calculated height and
strike the face of the CRT with an energy of (5,5 ± 0,1) J. The CRT shall be placed so that the
face is vertical and in the same vertical plane as the point of support of the pendulum.
A single impact shall be applied to any point on the CRT face at a distance of 40 mm or
greater from the edge of the useful phosphor screen.
NOTE The test laboratory should consider all their test set-up uncertainties to ensure this 40 mm minimum
position of the point of impact.
The barrier shall be placed 1,5 m from the plane of the centre of the face of the CRT
(see figure 2).
8.1.2 Glass throw criteria
A CRT is in compliance if the expulsion of glass within 5 s of the initial impact meets the
following requirements:
a) there shall be no glass particle (a single piece of glass having a mass greater than
0,025 g) past the 1,5 m barrier;
b) the total mass of all pieces of glass past the 1,5 m barrier shall not exceed 0,1 g.

– 12 – 61965 © IEC:2000(E)
8.2 Implosion test (missile)
8.2.1 Test procedure
The face of the CRT at the top and bottom shall be scratched (3 ± 1) mm from the screen or

phosphor edge into the viewing area. The scratches shall be horizontal lines (100 ± 5) mm long.

The impact object shall be a steel missile (see example in figure 3) with a mass of (2,3 ± 0,1) kg,

a minimum C scale Rockwell hardness of 60 and having one end rounded on a radius of

(25 ± 0,5) mm.
The CRT shall be subjected to a single impact, intending to cause rapid devacuation using the
minimum energy within the range. The impact object shall be swung through an arc of a
pendulum to obtain an impact of not less than 7,0 J and not more than 14,0 J to cause rapid
devacuation of the samples in the test group.
The impact area shall be the area bounded by two concentric circles where the radius of one
circle is one-sixth of the height of the useful phosphor screen and the second circle radius is
one-half of the height of the useful phosphor screen less 50 mm (see figure 4). In figure 4, if
R is less than R then the impact shall be applied to the circle specified in R .
2 1 1
NOTE Previous testing experience on a particular CRT design (obtained from the CRT manufacturer or the test
laboratory) should be considered when selecting the energy level within the range and the impact location.
The impact object travel shall be restricted so that the rounded end of the missile penetrates
the CRT face equal to, or less than 25 mm (see figure 5).
Barriers shall be placed 1,0 m and 1,5 m from the vertical plane of the centre of the face of
the CRT (see figure 5).
If no CRTs devacuate as a result of this test then the alternative implosion test (missile)
described in 8.2.3 shall be carried out.
8.2.2 Glass throw criteria
A CRT is in compliance if the expulsion of glass within 5 s of the initial impact meets the
following requirements:
a) there shall be no single piece of glass having a mass greater than 15 g between the 1,0 m
and 1,5 m barriers;
b) the total mass of all pieces of glass between the 1,0 m and 1,5 m barriers shall not exceed 45 g;
c) there shall be no single piece of glass having a mass greater than 1,5 g beyond the 1,5 m

barrier.
8.2.3 Alternative implosion test (missile)
This alternative test shall be used as an additional test when the test in 8.2.1 has devacuated
no CRTs, or may be used as an alternative to the test in 8.2.1 when it can be shown that
the 8.2.1 test is unlikely to devacuate at least one CRT of the sample group.
8.2.3.1 Test procedure
As in 8.2.1, except that the impact object will be a steel missile (see example in figure 10)
with a mass of (1,4 ± 0,1) kg, a minimum C scale Rockwell hardness of 60 and one end
rounded on a radius of (15 ± 0,5) mm.

61965 © IEC:2000(E) – 13 –
8.2.3.2 Glass throw criteria
As in 8.2.2. If no CRTs devacuate as a result of the test in 8.2.3.1, then the glass throw

requirements of 8.2.2 are deemed to have been satisfied.

8.3 Implosion test (thermal shock)

8.3.1 Test procedure
The CRT shall be mounted in the test cabinet which is described in 7.3 and 7.4. The barrier
shall be placed at (150 ± 2) mm from the vertical plane of the centre of the face of the CRT.
An area shall be scratched on the faceplate sidewall or face of the CRT using one of the

patterns illustrated in figure 6.
A thermal shock shall be applied using one of the following methods.
a) Liquid nitrogen
The scratched area shall be cooled using liquid nitrogen until a fracture occurs. A dam of
modelling clay or equivalent may be used to contain the liquid nitrogen.
b) Hot rod
The end of an ordinary flint glass rod, of suitable diameter (for example, 10 mm) shall be
heated until it is red hot and nearly fluid. The heated end of the rod shall be pressed firmly
on the scratched area of the CRT. If devacuation of the CRT does not occur within 10 s
then the rod shall be withdrawn and cold water poured slowly on the scratched area. If a
devacuation cannot be induced by repeated applications of the hot rod then the test shall
be carried out using liquid nitrogen (see 8.3.1a)).
8.3.2 Glass throw criteria
A CRT is in compliance if, within 5 s of the initial fracture, no glass particle is expelled through
the plane of the face beyond the 150 mm barrier.
8.4 High-energy impact test
CRTs which have a laminated implosion protection system shall be subjected to the following
high-energy impact test.
8.4.1 Test procedure
A (25 ± 1) mm diameter steel pin (see figure 8) shall be inserted through the hole at the top of
the test cabinet and placed on the CRT envelope (3 ± 1) mm behind the seal of the faceplate

and funnel. If the hardware extends back from the seal more than 3 mm so as to interfere with
the placement of the pin, then the pin shall be placed as close as possible to the hardware
without touching it. A weight (see figure 9a), having a mass of (4,5 ± 0,1) kg, shall be caused
to fall from a height so as to impact the pin at the end of its fall.
The height of the test mass shall be adjusted to limit the amount of energy to the minimum
required to produce fracturing of the glassware, but not less than 7 J.
If fracturing of the glass does not occur, the impact energy shall be increased in 7 J
increments to a maximum of 63 J using a new test sample each time until all the CRTs in the
test group have suffered rapid devacuation.

– 14 – 61965 © IEC:2000(E)
The impact energy shall not be so large as to cause the pin to punch a hole with little or no
cracking or shaling of the glassware. If this condition does occur then a lower impact energy

shall be selected so as to result in fracturing (7 J steps not necessary).

NOTE Previous testing experience on a particular CRT design (obtained from the CRT manufacturer or the test

laboratory) should be considered when selecting the energy level within the range.

The implosion pin shall be restricted so that its travel on impact shall be a maximum of 6 mm.

The pin travel restriction assembly shall be positioned so that its impact energy shall not be

transferred to the test cabinet. Figures 7, 8 and 9 give examples of equipment that may

be used.
Barriers shall be placed 1,0 m and 1,5 m from the plane of the centre of the face of the CRT.
8.4.2 Glass throw criteria
A CRT is in compliance if the expulsion of glass within 5 s of the initial impact meets the
following requirements:
a) there shall be no single piece of glass having a mass greater than 15 g between the 1,0 m
and 1,5 m barriers;
b) the total mass of all pieces of glass between the 1,0 m and 1,5 m barriers shall not exceed 45 g;
c) there shall be no single piece of glass having a mass greater than 1,5 g beyond the 1,5 m
barrier.
9 Testing of small CRTs
9.1 Mechanical strength (ball impact test)
9.1.1 Test procedure
A solid smooth steel ball of (40 ± 1) mm diameter and mass of (260 ± 15) g, including the
hook, and a minimum C scale Rockwell hardness of 60, shall be suspended by suitable
means such as a fine wire or chain with a mass not exceeding 10 % of the mass of the ball
and hook. It shall be allowed to fall freely as a pendulum from a calculated height and strike
the face of the CRT with an energy of (2,0 ± 0,1) J. The CRT shall be placed so that the face
is vertical and in the same vertical plane as the point of support of the pendulum. A single
impact shall be applied to any point on the CRT face at a distance of 25 mm or greater from
the edge of the useful screen.
NOTE The test laboratory should consider all their test set-up uncertainties to ensure this 25 mm minimum
position of the point of impact.

The barrier shall be placed 0,6 m from the plane of the centre of the face of the CRT
(see figure 2).
9.1.2 Glass throw criteria
A CRT is in compliance if the expulsion of glass within 5 s of the initial impact meets the
following requirements:
a) there shall be no glass particle (a single piece of glass having a mass greater than
0,025 g) past the 0,6 m barrier;
b) the total mass of all pieces of glass past the 0,6 m barrier shall not exceed 0,1 g.

61965 © IEC:2000(E) – 15 –
9.2 Implosion test (high ball)

If implosion or rapid devacuation does not occur when the CRT is tested as specified in 9.1

then a CRT having other than a laminated implosion protection system shall be subjected to

the following test.
9.2.1 Test procedure
The face of the CRT shall be scratched at the top and bottom edges (3 ± 1) mm from the

screen phosphor edge into the viewing area. The length of the scratches shall be 45 % to

55 % of the longest dimension/width of the face of the CRT.

Using a (40 ± 1) mm diameter steel ball having a mass of (260 ± 15) g and a minimum C scale
Rockwell hardness of 60, a CRT having other than a laminated implosion screen shall be
subject to additional impact tests during which the impact energy shall be increased in 0,7 J
increments until fracturing occurs. A new sample shall be used for each test until all CRTs in
the test group have been tested, with implosion or rapid devacuation occurring.
Barriers shall be placed 0,6 m and 1,2 m from the plane of the centre of the face of the CRT
(see figure 2).
9.2.2 Glass throw criteria
A CRT is in compliance if the expulsion of glass within 5 s of the initial impact meets the
following requirements:
a) there shall be no single piece of glass having a mass greater than 15 g between the 0,6 m
and 1,2 m barriers;
b) the total mass of all pieces of glass between the 0,6 m and 1,2 m barriers shall not exceed 45 g;
c) there shall be no single piece of glass having a mass greater than 1,5 g beyond the 1,2 m
barrier.
9.3 Implosion test (thermal shock)
9.3.1 Test procedure
As 8.3.1.
9.3.2 Glass throw criteria
As 8.3.2.
9.4 High-energy impact test
CRTs which have a laminated implosion protection system shall be subjected to the following
high-energy impact test.
9.4.1 Test procedure
A (9,5 ± 0,5) mm diameter steel pin shall be inserted through the hole in the top of the test
cabinet and placed directly on the envelope seal line. A weight (see figure 9b) having a mass
of (0,45 ± 0,02) kg, shall be caused to fall freely from a height so as to impact the pin at the
end of its fall.
– 16 – 61965 © IEC:2000(E)
The height of the test mass shall be adjusted to limit the amount of energy to the minimum
amount required to produce fracturing of the glassware, but not less than 2,7 J.

If fracturing of the glass does not occur, the impact energy shall be increased in 0,7 J
increments, using a new test sample each time, until all CRTs in the test group have been

tested with rapid devacuation.

The impact energy shall not be so large as to cause the pin to punch a hole with little or no

cracking or shaling of the glassware. If this condition does occur then a lower impact energy

shall be selected so as to result in fracturing (0,7 J steps not necessary).

NOTE Previous testing experience on a particular CRT design (obtained from the CRT manufacturer or the test
laboratory) should be considered when selecting the energy level within the range.
The impact pin shall be restricted so that its travel on impact shall be a maximum of 6 mm.
The pin travel restriction assembly shall be positioned so that impact energy shall not be
transferred to the test cabinet. Figures 7, 8 and 9 give examples of equipment that may
be used.
Barriers shall be placed 0,6 m and 1,2 m from the plane of the centre of the face of the CRT.
9.4.2 Glass throw criteria
A CRT is in compliance if the expulsion of glass within 5 s after the initial impact meets the
following requirements:
a) there shall be no single piece of glass having a mass greater than 15 g between the 0,6 m
and 1,2 m barriers;
b) the total mass of all pieces of glass between the 0,6 m and 1,2 m barriers shall not exceed 45 g;
c) there shall be no single piece of glass having a mass greater than 1,5 g beyond the 1,2 m
barrier.
10 Marking
Along with the CRT manufacturer’s name, trade name or identifying code, and a type number,
each CRT which meets the requirements of this standard shall be marked with the following
statement, or wording with a similar meaning. The marking shall be of a permanent and
legible type and in the appropriate language.
WARNING. This cathode ray tube employs integral implosion protection.
For continued safety it must be replaced with a cathode ray tube of the same or
equivalent type number.
11 Normative requirements for the use of tables 1 and 2
(prestressed banded CRTs)
Sampling and testing for new construction (sampling plan I), new construction with known
tape or resin (sampling plan II), tension band only (sampling plan III) and alternative
construction (sampling plan IV) will be used when any of the following new construction
features or variations in construction apply. Unique constructions may require a special
investigation.
61965 © IEC:2000(E) – 17 –
11.1 Sampling plan I: New construction

Applicable to first-time testing for a CRT manufacturer or a change in construction of a

previously tested CRT that employs any of the following nominal design changes:

11.1.1 Size
New CRT diagonal size range (see table 7).

11.1.2 Deflection angle
New deflection angle range for a particular CRT size range (see table 7).
11.1.3 Glassware shape
Glassware in a particular CRT size and deflection angle range, having the following shape
variations, is considered a new glassware shape.
a) front panel outside curvature – a change in height measurement from the Z point to the
centre of the face panel of more than ±10 % from a previously tested CRT for a
manufacturer;
b) aspect ratio – any change in the height-to-width ratio of the front panel from a previously
tested CRT for a manufacturer;
c) glassware thickness – a change in glassware thickness of more than ±20 % at any point,
other than the neck, from a previously t
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