IEC 62679-3-2:2013

IEC 62679-3-2 ®
Edition 1.0 2013-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electronic paper display –
Part 3-2: Measuring method – Electro-optical

Afficheur de papier électronique –
Partie 3-2: Méthode de mesure – Electro-optique

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IEC 62679-3-2 ®
Edition 1.0 2013-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electronic paper display –
Part 3-2: Measuring method – Electro-optical

Afficheur de papier électronique –

Partie 3-2: Méthode de mesure – Electro-optique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX T
ICS 31.120; 31.260 ISBN 978-2-8322-1044-4

– 2 – 62679-3-2 © IEC:2013
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Abbreviations . 6
3 Overview . 6
3.1 General . 6
3.2 Measuring equipment . 6
3.3 Standard locations of measurement field . 7
3.3.1 Matrix displays . 7
3.3.2 Segment displays . 7
3.4 Initial reflectance light signal . 8
3.5 Standard DUT operating conditions . 9
3.5.1 General . 9
3.5.2 Response time. 9
3.5.3 Frame response . 11
3.6 Electrical characteristics – Rewriting electric energy . 15
3.6.1 Purpose . 15
3.6.2 Measuring instruments . 15
3.6.3 Measuring method . 15
3.6.4 Explanation . 16
3.6.5 Specified conditions . 17
3.7 Image retention duration . 17
3.7.1 Purpose . 17
3.7.2 Measuring instruments . 17
3.7.3 Measuring method . 17
3.7.4 Explanation . 18
3.7.5 Specified conditions . 18
3.8 Electric power of keeping the image contrast . 19
3.8.1 Purpose . 19
3.8.2 Measuring instruments . 19
3.8.3 Measuring method . 19
3.8.4 Explanation . 20
3.8.5 Specified conditions . 20
3.9 Electric energy of keeping the image contrast for a certain time period . 21
3.9.1 Purpose . 21
3.9.2 Measuring instruments . 21
3.9.3 Measuring method . 21
3.9.4 Explanation . 22
3.9.5 Specified conditions . 23
Bibliography . 24

Figure 1 – Measurement locations of display active area . 7
Figure 2 – HL pattern . 8
Figure 3 – Sampling points . 8
Figure 4 – An example of block diagram of an electronic paper display panel and
module . 10
Figure 5 – Relationship between driving signal and optical response time . 10

62679-3-2 © IEC:2013 – 3 –
Figure 6 – An example of driving signal and frame response time (segment) . 13
Figure 7 – An example of driving signal and frame response time (matrix) . 14
Figure 8 – Checkerboard pattern . 16
Figure 9 – An example of block diagram for measuring the rewriting electric energy of
an electronic paper display module . 16
Figure 10 – Temporal characteristics of contrast ratio . 18
Figure 11 – Image contrast and driving mode. 19
Figure 12 – Image contrast, driving mode and measuring period . 22

– 4 – 62679-3-2 © IEC:2013
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRONIC PAPER DISPLAY –
Part 3-2: Measuring method –
Electro-optical
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
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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.
International Standard IEC 62679-3-2 has been prepared by IEC technical committee 110:
Electronic display devices.
The text of this standard is based on the following documents:
FDIS Report on voting
110/475/FDIS 110/502/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 2.
A list of all parts in the IEC 62679 series, published under the general title Electronic paper
display, can be found on the IEC website.

62679-3-2 © IEC:2013 – 5 –
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication 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 – 62679-3-2 © IEC:2013
ELECTRONIC PAPER DISPLAY –
Part 3-2: Measuring method –
Electro-optical
1 Scope
This part of IEC 62679 series is restricted to electronic paper display modules using either
segment, passive, or active matrix, and either monochromatic, or colour type displays.
In order to achieve a useful and uniform description of the performance of these devices,
specifications for commonly accepted relevant parameters are put forward.
The purpose of this part of IEC 62679 series is to indicate and list the procedure-dependent
parameters and to prescribe the specific methods and conditions that are to be used for their
uniform numerical determination.
2 Abbreviations
DUT – Device under test
LMD – Light measuring device
PWM – Pulse width modulation
3 Overview
3.1 General
It is intended that the future IEC 62679-3-1 will cover the proper illumination method and
optical measurement method to evaluate the electro-optical property of electronic paper
display modules.
If an electronic paper display module works in combination with an external touch-key-panel
or an external front-light-unit, remove those for measuring. If it is not possible to remove
these elements, this fact shall be mentioned. However, it is not necessary to mention the
protective sheet.
It is assumed that all measurements are performed by personnel skilled in the general art of
radiometric and electrical measurements as the purpose of this paper is not to give a detailed
account of good practice in electrical and optical experimental physics. Furthermore, it is
necessary to ensure that all equipment is suitably calibrated as is known to skilled personnel
and that records of the calibration data and traceability are kept.
It is assumed that all measurements are performed under normal operation conditions as
used in the finished product by the end user unless requested otherwise. This includes the
driving signals (waveforms) of the electronic paper display panel and/or module.
NOTE An electronic paper display module consists of an electronic paper display panel (electro-optical material,
back plane, and driving circuit) and a logic circuit (see Figure 4).
3.2 Measuring equipment
Luminance meter: the devices for measuring luminance can be realized by
• a spectro-radiometer with numerical V(λ) correction

62679-3-2 © IEC:2013 – 7 –
• a photometer with filter adaption to V(λ)
where V(λ) is the photopic response, as defined by the CIE 1931 standard observer in
CIE/ISO 10527:1991.
Colorimeter: devices for measuring colour can be realized by
• spectro-radiometer with numerical evaluation (spectrophotometer),
• filter-colorimeter
3.3 Standard locations of measurement field
3.3.1 Matrix displays
P23 P24 P9 P10 P11
P22 P8 P1 P2 P12
P21 P7 P0 P3 P13
P20 P6 P5 P4 P14
P19 P18 P17 P16 P15
(1/10)H
(3/10)H
(5/10)H
IEC  2137/13
NOTE Standard measurement positions are at the centres of all rectangles P0 to P24. Height and width of each
rectangle are 20 % of display active area height and width respectively.
Figure 1 – Measurement locations of display active area
Luminance, spectral distribution and/or tristimulus measurements may be taken at several
specified positions on the DUT surface. To this end, the front view of the display is divided
into 25 identical imaginary rectangles (see Figure 1). Unless otherwise specified,
measurements are carried out in the centre of each rectangle. Care shall be taken that the
measuring spots on the display do not overlap. Positioning of the measuring spot on the thus
prescribed positions in the x and y axis shall be to within 7 % of V and H respectively (where
V and H denote the length of the display active area in the x and y axis respectively).
While scanning the position of the measuring spot over the surface of the DUT, the polar
angles shall stay fixed.
Any deviation from the above-described standard positions shall be added to the detail
specification.
3.3.2 Segment displays
Standard measurement positions are the same as those prescribed for the matrix displays
above. However, for segment displays, all measurements shall be performed at the centre of
a segment and the chosen segment should be as close as possible to the centre of the
designated rectangle. Thus, when measurements on position Pi (i = 0 to 24) are requested,
(5/10)V
(3/10)V
(1/10)V
H
– 8 – 62679-3-2 © IEC:2013
the geometrical centre of the segment closest to the centre of box Pi should be used for
positioning of the detector.
Any deviation from the above-described standard positions shall be mentioned.
3.4 Initial reflectance light signal
Measuring method:
Send an HL pattern (see Figure 2) that has a 50 % cover ratio to an electronic paper display
module by using a pattern generator and a driving circuit. Stop driving that electronic paper
display module (do not send any command nor data). Select one proper physical condition of
lighting and measuring method. Measure 5 points each (see Figure 3) in both areas of high
and low reflected optical signal. Calculate the average of those 5 points to obtain the initial
reflectance of Ref and Ref . Calculate the initial contrast, CR , from Ref and Ref .
max min i max min
CR = Ref /Ref
i min max
IEC  2138/13
The 'black' area shall have the lowest reflected optical signal while the 'white' area shall have the highest reflected
optical signal.
Figure 2 – HL pattern
Sampling point
1/8V 1/8V 1/8V 1/8V 1/8V 1/8V 1/8V 1/8V
½ V ½ V
IEC  2139/13
Figure 3 – Sampling points
¼H ¼H ¼H ¼H
62679-3-2 © IEC:2013 – 9 –
3.5 Standard DUT operating conditions
3.5.1 General
Depending on the physics of some electronic paper display module types, optical properties of
these modules vary with the direction of observation (i.e. viewing-direction). Therefore it
should be understood that for the determination of several of the parameters below, proper
(mechanical) control and specification of the viewing direction is necessary. The normal
viewing direction should be the default viewing direction, and the LMD aligned perpendicular
to the DUT surface, unless stated otherwise. For viewing direction dependence, the process
that will be described in IEC 62679-3-1 can be followed.
All light sources used for illumination of the DUT during the measurement shall be constant in
illuminance and spectrum at least over the time-period of measurements that are related to
each other in the evaluation (e.g. bright and dark state of a display for contrast evaluation).
The luminance or illuminance of the arrangement used for illumination of the DUT shall be
constant within ± 1 %, and shall not exhibit short-term fluctuations (e.g. ripple, PWM, etc.).
Measurements shall be started after the DUT, the source illumination, and measuring
instruments achieve stability. Constant and correct temperature of the DUT shall be verified.
The module being tested shall be physically prepared for testing. It should be thermostatically
controlled for stable operation during a specified period being less than one hour. If the
control period is less than one hour, stable temperature shall be verified. Testing shall be
conducted under nominal conditions of driving signal (voltage, current, waveform). Any
deviation from the standard device operation conditions shall be added to the detail
specification.
3.5.2 Response time
3.5.2.1 Purpose
This method is used for the determination of the time needed to change from high to low
reflected optical signal (light to dark) or from low to high reflected optical signal (dark to light)
by application of the driving voltage.
By convention, the response of an electronic paper display module to an increase in driving
voltage is called ‘turn-high’ whereas the relaxation following a decrease of the driving voltage
is called ‘turn-low’. While this definition is straightforward in the case of segment- and low-
resolution displays, it is significantly more complicated in the case of high resolution matrix
displays, due to the complexity of data processing.
In order to measure a meaningful response time for the electronic paper display module, it is
recommended to evaluate a response time for the actual driving signal for an electronic paper
panel of that display. This requires having access to the electrical signal that is applied to the
electronic paper display panel.
3.5.2.2 Measurement equipment
An LMD with sufficient frequency response, a power supply, a driving signal generator, a
trigger signal generator, and a recorder.
3.5.2.3 Measurement method
The measurements are performed in the dark room under standard measuring conditions.
Drive the DUT according to the display driving method and measure the reflection-time
transition (see Figure 5). For segment display, drive only one segment. For matrix display,
drive multiple pixels at the same time.

– 10 – 62679-3-2 © IEC:2013
Driving power supply
Driving circuit
Logic circuit
Electronic paper display panel
Electronic paper display module

IEC  2140/13
Figure 4 – An example of block diagram of an electronic
paper display panel and module
T T
1 2
Y Y
T T
p1 p2
100% 100%
90% 90%
10% 10%
0% 0%
t t
t t
1 2
Driving Driving
Signal Signal
Driving Driving
for module for module
Driving Driving
for panel for panel
t t
IEC  2141/13
T – time from start of the module driving signal until panel reaches 10% of reflected optical signal
T – time from start of the module driving signal until panel reaches 90% of reflected optical signal
T – time from start of the panel driving signal until panel reaches 10% of reflected optical signal
p1
T – time from start of the panel driving signal until panel reaches 90% of reflected optical signal
p2
t – time needed to change the reflected optical signal of the panel from 90% to 10%
t – time needed to change the reflected optical signal of the panel from 10% to 90%
Figure 5 – Relationship between driving signal and optical response time

62679-3-2 © IEC:2013 – 11 –
a) Select one of the standard measuring systems and set the DUT.
b) Use the measurement circuits system as shown in Figure 4, and measure response time.
The electrical signal of the detector, which is positioned in the design-viewing direction at
position P0 (see Figure 1), is measured at the recorder. The display is driven by an invertible
plain field signal from a signal generator. Upon inverting, the signal goes from start level to
end level without displaying any intermediate level on the display. The frequency of inversion
shall be low enough to allow the display to obtain optical equilibrium in each of the two states.
A trigger signal is sent to the recorder upon inversion of the reflected optical signal at position
P0. The luminance meter measures the optical response. Ripples in the detected signal due
to effects that are not relevant (e.g. originating from the display frame-frequency) shall be
eliminated from the response. The reflected optical signal in the LIGHT mode is chosen as
100 % and in the DARK mode as 0 %.
3.5.2.4 Explanation
• The time from the start of the module driving signal until the panel reaches 90 % or 10 %
of the reflected optical signal is called ‘module response time’.
• The time from the start of the module driving signal until the panel reaches 10 % of the
reflected optical signal (from HIGH to LOW) is T .
• The time from the start of the module driving signal until the panel reaches 90 % of the
reflected optical signal (from LOW to HIGH) is T .
• The time from the start of the panel driving signal until the panel reaches 90 % or 10 % of
the reflected optical signal is called ‘panel response time’.
• The time from the start of the panel driving signal until the panel reaches 10 % (from HIGH
to LOW) of the reflected optical signal is T .
p1
• The time from the start of the panel driving signal until the panel reaches 90 % (from LOW
to HIGH) of the reflected optical signal is T .
p2
• The time needed to change the reflected light signal of the panel from 90 % to 10 % or
from 10 % to 90 % is called ‘fall time’,t or ‘rise time’,t .
1 2
NOTE 0 % is the minimum reference reflected optical signal level, and 100% is the maximum reference reflected
optical signal.
3.5.2.5 Specified conditions
The records of the measurement shall be made to describe deviations from the standard
measurement conditions and include the following information:
• selected standard measuring system and its related conditions;
• driving signals (waveforms, voltage);
• measurement equipment and detector specifications;
• if not measuring the ‘panel response time’, note that.
3.5.3 Frame response
3.5.3.1 Purpose
This method is used for the assessment of the frame response time of both segment and
matrix electronic paper display modules. This response includes any stabilization period used
by the device after the initial leading edge of the drive signal to create the frame.
3.5.3.2 Measurement equipment
Same as in 3.5.2.2.
– 12 – 62679-3-2 © IEC:2013
3.5.3.3 Measurement method
Measure the transition period from the displaying of the highest to the lowest reflected optical
signal, and the lowest to the highest reflected optical signal. If the DUT requires a certain kind
of process, such as a stabilizing process before writing the actual data to the DUT with a
certain signal, start measuring by inputting that signal (see Figure 6). Normally the driving
signals (waveforms) of the electronic paper display module are used. If these driving signals
include a preliminary process such as ‘Reset’ or ‘stabilization’ before writing the actual image
data to the module, start measuring the response times T or T from the start of that process.
1 2
For the matrix display, measure that period by changing pattern A to pattern B or pattern B to
pattern A (see Figure 7). The measuring location Pf is the last changed location in the
standard measuring locations shown in Figure 7.
Other measuring methods follow 3.5.2.3.

62679-3-2 © IEC:2013 – 13 –
Y
Y
100% 100%
90% 90%
10% 10%
0%
0%
t t
T
T
1 2
Driving Driving
signal signal
Driving Driving
t t
IEC  2142/13
Y
100%
90%
10%
0%
t
T
Driving
signal
Driving
t
With stabilizing process
Y
100%
90%
10%
0%
t
T
Driving
signal Driving
t
With stabilizing process
IEC  2143/13
Y – reflected optical signal
t – time
Figure 6 – An example of driving signal and frame response time (segment)

– 14 – 62679-3-2 © IEC:2013
Measuring point
Y
Y
100% 100%
Pattern A 90% 90%
10% 10%
0%
0%
t t
T
1 T
Driving Driving
signal signal
Pattern B Driving Driving
t t
Without stabilizing process
IEC  2144/13
Y
100%
90%
10%
0%
t
T
Driving
signal
Driving
t
With stabilizing process (HIGH->LOW)
Y
100%
90%
10%
0%
t
T
Driving
Signal
Driving
t
With stabilizing process (LOW->HIGH)
IEC  2145/13
Y – reflected optical signal
t – time
Figure 7 – An example of driving signal and frame response time (matrix)
3.5.3.4 Explanation
To change from the highest reflection to the lowest reflection, the time needed for the
reflected optical signal to change from 100 % to 10 % (T ) is measured. To change from the
62679-3-2 © IEC:2013 – 15 –
lowest reflection to the highest reflection, the time needed for the reflected optical signal to
change from 0 % to 90 % (T ) is measured.
If the driving signals (waveform) of the DUT include a preliminary process such as
‘stabilization’ or ‘Reset’ to change from the highest reflection to the lowest reflection, the time
needed for the reflected optical signal to change from 100 % to 10 % including reset time (T )
is measured, and to change the lowest reflection to the highest reflection, the time needed for
the reflected optical signal to change from 0 % to 90 % including reset time (T ) is measured.
When measuring T the 10% threshold has to be crossed in the direction from higher to lower
reflected optical signal, and when measuring T the 90% threshold has to be crossed in the
direction from lower to higher reflected optical signal, at the end of the stabilization period.
3.5.3.5 Specified condition
The records of the measurement shall be made to describe deviations from the standard
measurement conditions and include the following information:
• selected standard measuring system and its related conditions;
• driving signals (waveforms, voltage);
• measurement equipment and detector specifications;
• if use is made of the term switching-time or (dynamic) response time, explanation of use
shall be given in the detail specification and deviations from prescribed nomenclature in
3.5.3.4 shall be given when using other names for any of these times;
• if the DUT shows another transition during a changing state, show that transition, perform
a similar measurement and define T , T , t , and t accordingly;
1 2 1 2
• for a matrix display module, describe the location of Pl (the last changed location that
shows a transition).
3.6 Electrical characteristics – Rewriting electric energy
3.6.1 Purpose
This method is applied to the measurements of electric energy for an electronic paper display
module, especially rewriting.
3.6.2 Measuring instruments
Rewriting electric energy is measured by using an LMD (luminance meter or colorimeter), a
driving power supply, a driving circuit, a pattern generator, voltage meters with timestamp,
and current meters with timestamp.
3.6.3 Measuring method
The measurements are performed under the standard measuring conditions. Send a
checkerboard pattern that has a 50 % covering ratio (see Figure 8) by using a pattern
generator and a driving circuit (pattern A in Figure 8). Then, send a reversed checkerboard
pattern (pattern B in Figure 8). Measure the electric energy during changing (rewriting) from
pattern A to pattern B. Both pattern A and pattern B should have the same contrast ratio
measured by a standard method. The actual rewriting process is dependent on each display.
Using a measuring circuit (shown in Figure 9), measure the electric energy during rewriting
from pattern A to pattern B. Electric energy is measured by voltage V , V , current I , I and
1 2 1 2
duration t.
Testing shall be conducted under nominal conditions of driving signal (voltage, current,
waveform).
– 16 – 62679-3-2 © IEC:2013
PPatattterernn A A PPatattterernn B B

IEC  2146/13
Figure 8 – Checkerboard pattern
Driving power supply
V            V                GND
1      2
I t Current I t
1 2
V t
V t
Voltage
Logic circuit Driving circuit
Electronic paper display panel

IEC  2147/13
Key
I , I – current
1 2
V , V – voltage
1 2
Figure 9 – An example of block diagram for measuring
the rewriting electric energy of an electronic paper display module
3.6.4 Explanation
3.6.4.1 Rewriting electric energy
Rewriting electric energy for the electric paper display module in each circuit is calculated
using the following formulae:
t
The electric energy of logic circuit W = V I dt (1)
1 1 1
∫
62679-3-2 © IEC:2013 – 17 –
t
The electric energy of electronic paper display driving circuit W = V I dt (2)
2 2 2
∫
The total rewriting electronic energy in the display module W = W + W (3)
1 2
where
V is the voltage
I is the current
W is the electric energy
If the logic circuit and the driving circuit are not separated, measure the compound current,
the superposed voltage and the time to calculate the total rewriting electric energy. In this
case, note the use of that method.
3.6.4.2 Maximum electric energy for rewriting
Adjust the conditions for the electronic paper display module driving current and driving
voltage which are specified in the detailed specification for the maximum electric energy. In
these conditions, the measured individual and the total electric energy are defined as the
corresponding maximum electric energy.
3.6.5 Specified conditions
In case of measuring under non standard conditions, specify what that is, such as:
• measuring conditions, such as the physical condition of light source and/or receptacle,
and/or the related required detail information (such as angle of incidence);
• in case of using a non standard checkerboard pattern, because of a physical limitation of
display(s), note the detailed information about used pattern, size, covering ratio (black
ratio);
• in case measurements using pattern A and/or pattern B have a different contrast ratio (if
the contrast ratio of used pattern is not 100% black nor 100% white), note the contrast
ratio of those patterns and the measured electric energy.
3.7 Image retention duration
3.7.1 Purpose
This method is applied to the measurement of the image retention duration of an electronic
paper display module.
3.7.2 Measuring instruments
Image retention duration is measured by using an LMD (luminance meter or colorimeter), a
driving power supply, a driving circuit, a pattern generator, and a timer.
3.7.3 Measuring method
The measurements are performed under the standard measuring conditions.
not instantly but after a fixed waiting period, for example 3 s.
Measure CR
i
Set the electronic paper display module with either pattern A or pattern B under the standard
condition. Measure the time t when the contrast of that electronic paper display module
becomes 80 % of CR . If required, other durations such as t for 60 % of CR , or t for 40 %
i 60 i 40
can be used.
of CR
i
– 18 – 62679-3-2 © IEC:2013
NOTE To test the usability requirements, if possible, it can be useful to measure the time t when the electric
x
paper display becomes barely readable by visual evaluation.
Figure 10 shows the relationship between contrast CR , and duration t .
x x
Contrast ratio
CR 1,0
i
CR = 0,8 × CR 0,8
80 i
CR = 0,X × CR 0,X
x i
CR = 0,Y × CR 0,Y
y i
Time
t t t
80 X Y
IEC  2148/13
Figure 10 – Temporal characteristics of contrast ratio
3.7.4 Explanation
The image retention duration is measured by using the following methods:
Initial contrast CR = Ref / Ref (4)
i max min
80 % of CR CR = 0,8 × CR (5)
80 i
NOTE CR in Figure 10 is normalized.
Image retention period: t time period from the start to when the contrast of that electronic
paper display module becomes 80 % of Cr .
i
Image retention period: t time period from the start to when the contrast of that electronic
Y
paper display module becomes Y % of CR .
i
3.7.5 Specified conditions
In case of not following the standard measuring method, specify what that is, such as:
• measuring conditions, such as the physical condition of light source and/or receptacle,
and/or the related required detail information (such as angle of incident);

62679-3-2 © IEC:2013 – 19 –
• in case of using a non standard checkerboard pattern, because of a physical limitation of
display(s), note the detailed information about the said pattern, size, and cover ratio
(black ratio);
• if measured from several CR (because of the characteristics of measuring the electronic
i
paper display module), record each CR in conjunction with t , t , t for each CR ;
i 80 60 40 i
• measuring conditions and retention conditions (environmental),
• if t is not measurable (the electronic paper display module never reaches CR within a
80 80
reasonable period), measure at a much higher contrast ratio, such as 95% or 90% of CR ,
i
and note those, such as t or t .
95 90
3.8 Electric power of keeping the image contrast
3.8.1 Purpose
This method is applied to the measurement of the electric power to keep the image contrast.
3.8.2 Measuring instruments
The electric power of keeping the image contrast is measured by using an LMD (luminance
meter or colorimeter), a driving power supply, a pattern generator, a voltage meter with
timestamp, and a current meter with timestamp.
3.8.3 Measuring method
The measurement is performed under the standard measuring conditions. Write the standard
image pattern (Figure 8) by using driving signals and a pattern generator with the
measurement circuit in Figure 9. The initial contrast ratio is calculated from the measured
reflectance ratio and called CR . After a non driving duration send electronic signal(s) in order
i
to ensure that the electronic paper display module has the same contrast CR . Measure the
i
required electronic power and required duration. (See Figure 11)
Contrast Ratio
CR 1,0
i
CR = 0,8 × CR 0,8
80 i
Non driving
Driving Non driving
t t
h d
Time
IEC  2149/13
Figure 11 – Image contrast and driving mode

– 20 – 62679-3-2 © IEC:2013
3.8.4 Explanation
The electric power of keeping the image contrast is defined as the electric energy required to
keep an electronic paper display module at the initial contrast condition after holding the
image for a certain period. That power is measured by using the driving duration (t ), the
d
current and voltage in order to bring back the contrast to the initial contrast ratio (CR ), which
i
is gradually decayed with the image retention duration.
Measure the powers for each portion as in the following formulae, and sum up to the total
power.
Power for the logic circuit P ＝W / ( t + t )  (6)
1 1 h d
t
d
W = V I dt (7)
1 1 1
∫
Power for the driving circuit P ＝W / ( t + t ) (8)
2 2 h d
t
d
W = V I dt (9)
2 2 2
∫
Total power of the electronic paper display module P ＝P + P (10)
1 2
where
V is the voltage
I is the current
P is the power
W is the electric energy
If the power for the logic circuit and the driving circuit cannot be measured separately,
measure the total power consumption, and use that as the power of that electronic paper
display module.
3.8.5 Specified conditions
In case of not following the standard measuring method, specify what that is, such as:
• measuring conditions, such as the physical condition of the light source and/or receptacle,
and/or the related required detailed information (such as angle of incidence);
• in case of using a non standard checkerboard pattern, because of a physical limitation of
display(s), note the detailed information about the said pattern, size, and cover ratio (black
ratio);
values (because of characteristics of the measuring
• if measured from several CR
i
electronic paper display module), record each CR in conjunction with t , t , t for each
i 80 60 40
;
CR
i
• measuring conditions and holding conditions (environmental);
• if the electronic paper display module never reaches CR within a certain period, note
that.
62679-3-2 © IEC:2013 – 21 –
3.9 Electric energy of keeping the image contrast for a certain time period
3.9.1 Purpose
This method is applied to the measurement of electric energy to keep the image contrast for a
certain time period
3.9.2 Measuring instruments
The electric energy of keeping the image contrast for a certain time period is measured by
using an LMD (luminance meter or colorimeter), a driving power supply, a pattern generator, a
voltage meter, a current meter, and a timer.
3.9.3 Measuring method
The measurement is performed under the standard measuring conditions. Write the standard
image pattern (Figure 8) by using driving signals and a pattern generator with the
measu
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