1、 IEC TR 62679-5-1 Edition 1.0 2017-07 TECHNICAL REPORT Electronic paper displays Part 5-1: Legibility of EPD in spatial frequency IEC TR 62679-5-1:2017-07(en) colour inside THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2017 IEC, Geneva, Switzerland All rights reserved. Unless otherwise specified
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10、h to give us your feedback on this publication or need further assistance, please contact the Customer Service Centre: csciec.ch. IEC TR 62679-5-1 Edition 1.0 2017-07 TECHNICAL REPORT Electronic paper displays Part 5-1: Legibility of EPD in spatial frequency INTERNATIONAL ELECTROTECHNICAL COMMISSION
11、 ICS 31.120; 31.260 ISBN 9978-2-8322-4527-9 Registered trademark of the International Electrotechnical Commission Warning! Make sure that you obtained this publication from an authorized distributor. colour inside 2 IEC TR 62679-5-1:2017 IEC 2017 CONTENTS FOREWORD . 3 INTRODUCTION . 5 1 Scope 6 2 Re
12、ferences 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 assessmen
13、t 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 o
14、f 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 v
15、ersus prediction score (VL) of EPD 16 Table 1 Properties of five kinds of paper 9 Table 2 EPDs for verification 16 IEC TR 62679-5-1:2017 IEC 2017 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ ELECTRONIC PAPER DISPLAYS Part 5-1: Legibility of EPD in spatial frequency FOREWORD 1) The International Ele
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27、t when it has collected data of a different kind from that which is normally published as an International Standard, for 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 IE
28、C 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 d
29、rafted 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
30、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. A bilingual version of this publication may be issued at a later date. IMPORTANT The col
31、our 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. IEC TR 62679-5-1:2017 IEC 2017 5 INTRODUCTION A small device fo
32、r an electronic paper display (EPD)11was 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 de
33、finition 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,
34、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 h
35、uman 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 retin
36、a 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 o
37、f 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
38、 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 environment
39、s. This document offers permanent formulae to decide on the legibility level of EPD compared with paper, which will lead to specification of EPD with regard to the human action of reading. Legibility is one of the human actions of reading, which falls in the category of subjective assessments; on th
40、e other hand, the properties of EPDs fall in that of physical specifications, that is, objective assessments. The legibility in this document described by using a five-level rating system is revealed to show as a function of physical parameters. In this document, legibility is suggested as having tw
41、o essential parameters, that is, the spatial frequency, which can represent the complexity or size of a letter, font, or symbol, and the contrast, which shows brightness between a character and its background. _ 1Numbers in square brackets refer to the Bibliography. 6 IEC TR 62679-5-1:2017 IEC 2017
42、ELECTRONIC PAPER DISPLAYS Part 5-1: Legibility of EPD in spatial frequency 1 Scope This part of IEC 62679, 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 EPD. This legibility e
43、valuation 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. 2 References There are no normative references in this document. 3 Terms, definitions and ab
44、breviated terms 3.1 Terms and definitions For the purposes of this document, the following terms and definitions apply 16. ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at http:/www.electropedia.org/ 4 ISO Online brow
45、sing platform: available at http:/www.iso.org/obp 3.1.1 contrast sensitivity test chart 5,6 CSC chart for measuring and quantifying visual sensitivity in terms of contrast sensitivity and spatial frequency response, which contains a multiplicity of grating patches whose contrast, in term of luminanc
46、e, varies sinusoidally for differing spatial frequencies Note 1 to entry CSC is sometimes used for diagnosis in ophthalmology clinics. 3.1.2 legibility ability for unambiguous identification of single characters or symbols that may be presented in a non-contextual format SOURCE: ISO 9241-302:2008, 3
47、.3.35 7 3.1.3 readability characteristics of a text presentation on a display that affect performance when groups of characters are to be easily discriminated, recognized and interpreted SOURCE: ISO 9241-302:2008, 3.3.38 7 IEC TR 62679-5-1:2017 IEC 2017 7 3.1.4 multiple regression analysis 8 analysi
48、s technique for composing a prediction formula which is easily and precisely calculated by making multiple selections for variables 3.1.5 spatial frequency component of an image transferred by Fourier transform SOURCE: ISO 9241-302: 2008, 3.5.48, modified the note has been removed. 7 3.2 Abbreviated
49、 terms CCD charge-coupled device CSC contrast sensitivity test chart CSF contrast sensitivity function EPD electronic paper display IR infrared SEP standard error of prediction 4 Contrast sensitivity test chart (CSC) CSC is mostly used in ophthalmologic diagnoses, to evaluate the progression of cataract or glaucoma 9 to 11. There was a US patent to define generalized visual sensitivity, but this idea has been already in the public domain 5, 6. CS
