NBSIR 76-991

Evaluation of Transparent Electro-Photographic

Film and Camera System

Thomas C. 3agg

Computer Systems Engineering Division

Institute for Computer Sciences and Technology

National Bureau of Standards

Washington, D.C. 20234

January 1975

Interim Report

Prepared for

Depart"ent of the Navy

Naval Suoply Systems Com.mand

Washington, D.C. 20376

NBSIR 76-991

Evaluation^ of Transparent Electro-Photographic

Film and Camera System

Thomas C. Bagg

Computer Systems Engineering Division

Institute for Computer Sciences and Technology

National Bureau of Standards

Washington, D.C. 20234

January 1976

Interim Report

Prepared for

Department of the Navy

Naval Supply Systems Command

Washington, D.C. 20376

U.S. DEPARTMENT OF COMMERCE, Elliot Richardson, Secretary Designate

James A. Baker, HI, Under Secretary

Dr. Betsy Ancker- Johnson , Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

Foreword

For a number of years, photographic recording materials with add-on capabilities, i.e.,

ability to add images to the original at a later time, have been discussed and demonstrated

in the laboratory.

Recently, one of these materials, the J:ransparent electrophotographic (TEP) medium, was used as the basis for a prototype camera-film system. Since there are many files requiring

an add-on microrecording systeii!, the Naval Supply Systems Command obtained a prototype TEP

system for a feasibility study. The prototype equipment was installed in the Navy Publishing

and Printing Branch at the Headquarters Building, Washington Navy Yard; and the National

Bureau of Standards was requested to assist in its evaluation.

Evaluating new materials and equipment for routine use requires development of test

procedures and extensive observations. This is an interim report covering the initial

observations.

The growing awareness of add-on film systems has created wide interest by both users

and potential suppliers. These groups are also testing similar and other types of add-on

material resulting in the availability of additional data. As data from further tests and

observations becomes available, additional reports will be made on such materials, particularly

the TEP type.

The Archivist of the United States has the responsibility for the recording of Federal

records and is deeply concerned with utilizing the most efficient methods; he is therefore

cooperating in this evaluation by having the Chief of the Technical Services Division of the

National Archives and Records Service work with NBS on this evaluation.

Table of Contents

Page

Introduction 1

Description of Transparent Electrophotography (TEP) 1

Results cf Observations 2

Summary 4

Evaluation of TEP Film and Camera System

.Interim Report to Naval Supply Systems Command

Thomas C. Bagg

On behalf of the Naval Supply Systems Command, the National

Bureau of Standards was requested to assist in the evaluation of new microfilm techniques and materials which permit the adding-on of images

at various times. This is an interim report on the initial evaluation

of the AB Dick/Scott System 200 which uses transparent electrophotographic

materials.*

Keywords: Add-on films; information storage; microforms; transparent

electrophotographic material.

Introduction

In an effort to utilize the many advantages of microforms for the management of current

files, a number of systems have been proposed and developed as substitutes for the file

jackets containing papers. Adding documents to a file jacket is a relatively simple m.anual

operation. It is, however, time consuming, leads to voluminous files, and is highly vulnerable to errors due to misfilinq. Further, due to its bulk, it is impractical to be duplicated

so items must be withdrawn from the file for varying periods of time which frequently creates

delays for other users and destroys file integrity. The more active a file, such as those

containing correspondence, personnel actions, medical histories, directives, etc., the more

serious the above mentioned problems become.

A properly designed and operated microform system can overcome many of the difficulties

by improving accessibility, reducing retrieval time, maintaining file integrity by permitting

inexpensive duplicates, reducing storage space and costs, etc. However, most microfilm systems

do not allow convenient file expansion or have add-on capability. In the past, systems using

microfilm jackets, i.e., transparent cards with pockets into which microimages may be slipped

or transparent cards to which individual document images may adhere, have been developed and

used. Such systems are expensive and require considerable manual effort.

The ideal solution would be the use of a film to which images could be added whenever

required. Therefore in recent years, several films have been announced using processes for

vesicular emulsions, thermoplastic, transparent electrophotographic materials and diffusion

transfer techniques. Of these, the Scott transparent electrophotographic (TEP) film and camera system appeared, in late 1974, to be the most advanced (now AB Dick/Scott - System 200).

In an effort to use the best advanced technology, the Naval Supply Systems Command installed

a prototype System 200 for feasibility tests in the Navy Publication and Printing Branch. The

goals of this study would be guidelines for the use of add-on microfilm systems for the effective handling cf active files.

The National Bureau of Standards was asked to assist the Naval Supply Systems Command in

eval^r-tir.g the AB Dick/Scott System 200 in the following three areas:

1. Image quality

2. Systems operation

3. Manufacturer's test results for determining the life expectancy of imaged and

unin-,aged film.

Description of Transparent Electrophotography (TEP)

Basically, the film is a transparent polyester sheet coated with a transparent electrical conducting material containing light sensitive compounds. This coating can be electrically charged over an area the size of a single microimage frame. It is then exposed through

*CGT-e r c 1 a 1 d e s i

g

nation s are provided for purposes of objective identification. Such

identification does not imply recommendation or endorsement by the National Bureau of

Star-.^3'"ds, nor does it imply that these products are necessarily the best for the purpose.

a lens in a conventional way to light reflected from a document. The electrical charges are dissipated in the areas receiving light but not in the areas representing printed information,

thereby forming a type of latent image. Very fine carbon particles oppositely charged are passed over the exposed area and adhere only to the remaining charged areas in the image.

These particles are permanently fixed to the film by radiant heat, resulting in a positive

image. "This is all done frame-by-frame so that uncharged, unexposed, and unprocessed areas

can at a later time be treated as descrioed to form images. Previously exposed and processed

frames can be re-exposed and reprocessed to 'add small amounts of information or, if needed, add

the word "VOID" to the original image by overprinting. The principle of this system is similar

to xerography or electrofax but uses reduced images and very fine toning materials.

To complete a system, Scott designed and built a camera which automatically exposes the

document to TEP film 'sheets cut to standard microfiche size and processes the images as outlined above. This camera also automatically moves the microfiche from frame-to-frame

during recording operations. For add-on images, the operator can set the camera to the

desired frame location prior to exposure. To prevent accidental double exposure, the camera

has a special sensor which detects an image in a frame and signals the operator so that no exposure will be made unless specifically instructed.

Results of Observations

The evaluation could not be completed within the time anticipated. Therefore, this

interim report presents the data obtained to date in each of the areas to be examined.

(1) Image quality -- Test targets and a series of document sheets, representing a wide

assortment of information that was difficult to record, were recorded by the System 200 and

examined for system response and image quality.

a. Resolution — The NBS 101 OA Microcopy Resolution Test Charts v/ere recorded by

three cameras on several occasions. The images were made with the Navy camera, a similar

camera at the Army Security Agency, and a model in the Scott laboratory. Typical data

obtained is shown in the following table:

Camera

Laboratory Model

Navy

ASA

Smallest Pattern

Resol ved

4.0 lines/mm

4.5

3.6

Reduction Ratio

27.4

23.9

26.6

Resolving Power

of System

110 lines/mm

108

96

It should be noted that some frames resolved the 5.0 l/mm throughout and that the tests

above were made on films currently available and do not reflect claimed improvements in new film coatings. Additional resolving tests will be made when new materials become

avai lable

.

b. Tonal Range (gray scale, density, contrast) -- The density of the base and

coatings in a clear area is about 0.35. When coated with a toner, the image area can reach

a density of at least 1.60. This gives an image contrast of about 1.25, which is well above

+ level needed to make suitable second generation prints on conventional duplicating films.

Due to field effects of the electrical charges, toner particles are not

held uniformly across large dark areas, thereby creating a lessening of the image

density in the center of large dark areas. Images of round solid areas of up to about

35^" in diameter seem to show a minimum of charge loss and coat reasonably uniformly. Preliminary tests showed 5 or 6 shades of gray could be recorded from a 7 step reflectance

wedge. These included the clear and black areas. Additional tests using wedges with more

steps and steps of different sizes are planned.

c. Self-Compensation for Non-White Documents -- Because the initial or latent

in-.age is formed by electrostatic charges, there appears to be soine self-adjusting for

exposure when recording documents with different background reflectivities due to color or discoloration of the paper. A group of sheets having a wide variation in paper colors and

ccnrrast with ink were recorded on TEP films and conventional silver halide microfilm to

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obtain an indication of this effect. With the TEP film, using a constant exposure, images

of good contrast were formed for documents having good contrast between the ink and the

paper, regardless of color. Except for the dark color papers, the background on the TEP

images appeared white. The darker papers showed some grayishness having a density of 0.44

which dfd not interfere with readability.

With silver halide film, the exposure had to be increased to- compensate for

the reduced background reflectiveness of the darker papers.

Very light colored inks (light gold, light yellow, light orange, etc.) on light papers frequently produced very light images with TEP, whereas the images on silver

films were slightly better if the exposure was readjusted.

Pictorial information with mostly dark tones or colors was difficult to

record on silver films; however, the TEP films produced quite acceptable images at the

fixed exposure.

(2) Operation of the System -- The system installed at the Navy Yard seemed, after

appropriate adjustment, to operate reliably and to be convenient for the operator.

In addition, operational data was obtained from tests on two other systems.

One was another prototype system observed in a New York bank. This camera was operated daily by a variety of inexperienced and disinterested operators who were adding

approximately 2,200 images per day with an average add-on of three pages per fiche. Further,

the supervisors who were observed, appeared careless in how they handled the master fiche

when making duplicates for the account managers. Despite this lack of concern, the camera continued to operate reliably and the images were quite satisfactory for the users' needs.

It was noted that occasionally, add-on images did not form properly on areas with heavy

fingerprints, a characteristic of most photosensitive materials.

The Army Security Agency (ASA) system is used for pilot ^ests to record financial

and travel records. The supervisor and camera operator liked the system very much and the

operator seemed to have no difficulty in recording a variety of documents, some of which

were poor, having been made on improperly adjusted office copy machines. Obviously some of

these sheets cannot produce good images, but this is a fault of the original copy rather

than the system. However, the self-compensating feature of the system appears to enhance

some poor copy. The operator says that she has had very little trouble with the system and

when there has been something that required adjustment, a serviceman was available for

repair. These services were rare and only a few of them required shutting down the system.

The most serious problem was due to a failure of the liquid toner mechanism. Since the

System 200 is prototype, it is to be expected that difficulties will develop which require

further work.

(3) Archival and Keeping Quality of Film -- Since this is a new type of photosensitive

material to be used for initial document recording over a period of tim.e, there is great

interest and concern in the shelf life of the unimaged material and the permanence of the

final images.

The film base is a polyester material which has been approved for use in permanent

recora films (ANSI PHI. 41 -1973, Specifications for Photographic Film for Archival Records , Silver Gelatin Type and Polyester Base ). The image is composed of carbon particles which

are inert. However, the stability and/or life expectancy of the binder used and the photosensitive compounds in the TEP coating have not been fully tested.

To obtain data on the permanence of imaged materials, members of the Scott staff

and the Director of Technical Services of the Archives met with MBS and outlined a program

which Scott would follow with the results submitted to NBS and the National Archives and

Records Service (NARS). Applicable tests and procedures were taken from ANSI Standards

PHI. 25-1974, Specifications for Safety Pho tographic Film ; PHI. 28-1973 , Specifications for

Photon raphic Film for Archival Re c ords, Si Ive r Ge l atin Type, on Cellulos e Ester ; PHI. 41-1973,

Specifications for Ph otographic Fi lm for Arc hival Po^ojl^ s_,_Sj J_y c_r _Ge 1 a t in Type and Polyester

Base and certain pertTnent tests from a draft standard for determining the permanence of

ncn-sllver materials.

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These tests represented a substantial amount of laboratory work; therefore,

AB Dick/Scott employed an independent testing laboratory familiar with testing photographic films to assist them. Preliminary tests and measurements indicated that further

testing was necessary before conclusive results could be reported. Such tests are underway.

The AB Dick/Scott position on these tests is stated in a letter from David Wolf,

Vice President in charge of marketing, dated 'August 22, 1975, copy attached. "While the

results are generally positive, test methodology in two areas made measurements difficult

and results subject to question. Additionally an anomaly not previously ooserved in the

sample of aged film warrants clarification and further study." Of major importance is the

fact that much of the inconclusive data appears related to the polyester film based

material. The results of these measurements will be of great concern to coaters of materials

on polyester other than the TEP.

None of the standards for archival films contain a scratch or abrasion test

because such films are to be carefully handled and not subjected to abuse. However,

an add-on film will be handled more than a film stored in an archive. To estimate the

abrasion resistance of TEP compared to silver, a pencil eraser and a knife blade were run over each emulsion. Very light pressure of an eraser produced very little effect on either,

but as the pressure was increased, the images on the TEP could be abraded slightly more than

the silver images. The knife point required about the same pressure to cause an effect of

about the same magnitude and then it really cut a groove in both materials. This was a very

subjective comparison. However, it appears the TEP image, when compared to a silver image,

can adequately withstand the type of handling recommended for all master negative materials.

Although the archival keeping properties of imaged areas appears to comply with

Federal requirements for master silver images when properly handled and stored, there is

uncertainty over the longevity of the sensitivity of non-imaged areas when the master TEP

film is used as a working copy. Prolonged exposures to high intensity light, such as found

in reader film gates and certain duplicators, will affect the film's ability to accept new

images. Each package of film contains such a warning as well as recoaimendati ens for the

film's use.

The manufacturer states that a full fiche can be duplicated at least 100 times

(number of copies per fiche) without failure of the imaging properties and believes the

imaging life, when the film is handled as recommended to be at least 20 years.

Further tests are required to definitively substantiate these claims and some

simple tests are being developed and tried in an effort to determine the imageability life.

Summary

Preliminary observations of system operations and tests of image quality and life

expectancy indicate the TEP system can adequately perform the function for which it was designed; that is, to produce a master copy with add-on image capability.

Because of the new technologies used in add-on film systems, evaluation tests and

procedures must also be developed. Such effort is being carried on by several laboratories

and as significant data on the performance of these materials becomes available, it will be

analysed and the results reported.

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