IEC TR 62679-5-1:2017
(Main)Electronic paper displays - Part 5-1: Legibility of EPD in spatial frequency
Electronic paper displays - Part 5-1: Legibility of EPD in spatial frequency
IEC TR 62679-5-1:2017, which is a technical report, specifies the legibility in terms of contrast, spatial frequency, and reflection of the screen as a function of the physical parameters of an electronic paper display (EPD). This legibility evaluation model is introduced through both subjective and objective assessments. The scope of this document is restricted to EPDs using segment, passive, and active matrixes with monochromatic type displays.
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IEC TR 62679-5-1 ®
Edition 1.0 2017-07
TECHNICAL
REPORT
colour
inside
Electronic paper displays –
Part 5-1: Legibility of EPD in spatial frequency
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IEC TR 62679-5-1 ®
Edition 1.0 2017-07
TECHNICAL
REPORT
colour
inside
Electronic paper displays –
Part 5-1: Legibility of EPD in spatial frequency
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.120; 31.260 ISBN 9978-2-8322-4527-9
– 2 – IEC TR 62679-5-1:2017 © IEC 2017
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 References . 6
3 Terms, definitions and abbreviated terms . 6
3.1 Terms and definitions . 6
3.2 Abbreviated terms . 7
4 Contrast sensitivity test chart (CSC) . 7
5 Objective assessment . 9
5.1 General . 9
5.2 Conditions of objective assessment . 10
5.3 Photometric characteristics for CSC . 10
6 Subjective assessment . 13
6.1 Conditions of subjective assessment . 13
6.2 Result of sensory evaluation . 14
7 Creating a legibility evaluation model . 15
7.1 Multiple regression analysis . 15
7.2 Results of multiple regression analysis . 15
7.3 Demonstration experiment . 16
7.4 Conclusion . 16
Bibliography . 18
Figure 1 – Layout of patches . 8
Figure 2 – Example of patch of CSC . 8
Figure 3 – Spatial frequency per unit viewing angle . 9
Figure 4 – Measuring apparatus geometry . 10
Figure 5 – Luminance distribution components . 12
Figure 6 – Examination environment . 14
Figure 7 – Result of sensory evaluation . 15
Figure 8 – Experimental score versus prediction score (VL) of EPD . 16
Table 1 – Properties of five kinds of paper . 9
Table 2 – EPDs for verification . 16
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRONIC PAPER DISPLAYS –
Part 5-1: Legibility of EPD in spatial frequency
FOREWORD
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example "state of the art".
IEC TR 62679-5-1, which is a technical report, has been prepared by IEC technical
committee 110: Electronic display devices.
– 4 – IEC TR 62679-5-1:2017 © IEC 2017
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
110/836/DTR 110/864A/RVDTR
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.
This document 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
displays, 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 "http://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.
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INTRODUCTION
A small device for an electronic paper display (EPD)[1] was invented in 1997, and its first
product as an electronic book was brought to the market in 2004. This product was the first
electronic display which made human beings serious about reading letters and figures as well
as those printed on a paper with ink. A definition of “electronic paper” was first given by N. K.
Sheridon et al of PARC in 1998, as follows: Plane paper scatters light diffusely and efficiently,
allowing for high contrast, high resolution images that can be viewed from broad angles
without glare caused by specular reflection, in contrast, electronic display media can provide
the extra benefits of reusability and easy integration into digital electronic systems. Electronic
display media used in such a fashion can be called “electronic paper” [2]. For these reasons,
the benchmark for estimation of EPD has always been printed paper.
The human action of reading is basically analysed through two subjective attributes, that is,
legibility and readability. The legibility, as defined at 3.1.2, can be rated and analyzed by
means of measuring optophysical or radiometric property of a certain pattern. This pattern is
recognised by the retina as an aggregation of spatial frequencies. Legibility can be
understood by analysing those kinds of spatial frequency. In 1967, the contrast sensitivity of
the human eye for sinusoidal illuminance changes was measured as a function of spatial
frequency [3]. As for readability, defined in 3.1.3, lot of human ergonomics tests and
sophisticated statistical works are recommended with around a hundred human participants,
to compare with printed paper, EPDs, and emissive displays; which will also require
economical costs and expenditure of time. The readability of EPDs will be reported elsewhere.
IEC 62679 (all parts) specifies optical measuring methods for electronic paper displays
(EPDs), but does not mention legibility and readability for EPDs, because there are no
guidelines for measuring and estimating these elements in a practical fashion, especially
under variation of optical environments.
This document offers p
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