Europâisches P a t e n t a m t
®
COi)
0 042
® Publication number:
Office
European
Eur°Pean Patent Office
B 1
Office européen des bbrevets
revets
@
EUROPEAN
PATENT
(§) Dateof publication of patent spécification: 27.03.85
8 6 9
SPECIFICATION
(g) Int. CL4: G 03 C 5/04,
G 03 B 2 7 / 7 2
(§) Application number: 81900375.7
(g) Date offiling: 23.12.80
(9) International application number:
PCT/US80/01719
(S) International publication number:
WO 81/01886 09.07.81 Gazette 81/16
(g) METHOD AND APPARATUS FOR FABRICATING A TRANSLUCENT GRADED DENSITY MEDIUM.
(g) Priority: 31.12.79 US 108877
_
(§) Date of publication of application:
06.01.82 Bulletin 82/01
(4§) Publication of the grant of the patent:
27.03.85 Bulletin 85/13
(fi) Designated Contracting States:
DE FR GB
O)
(O
GO
CM
o
o
û.
LU
@ Proprietor: NCR Corporation
World Headquarters
Dayton, Ohio 45479 (US)
(72) Inventor: HORST, William Richard
10165 Lebanon Pike
Dayton, OH 45459 (US)
@ Representative: Robinson, Robert George
International Patent Department NCR Limited
206 Marylebone Road
London NW1 6LY (GB)
(§) References cited:
DE-C-825205
US-A-2 051 584
US-A-2 083 215
US-A-2 150 805
US-A-3 224352
US-A-3 394003
US-A-3 642 477
US-A-3 694 079
US-A-3 797 934
US-A-3 996 051
US-A-4021831
US-A-4083 634
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may
give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall
be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been
paid. (Art. 99(1) European patent convention).
Courier Press, Leamington Spa, England.
Technical Field
The invention relates to a method and
apparatus for fabricating a translucent graded
density medium.
Background Art
The medium of the present invention may,
among other uses, be used for measurement of
mechanical motion or displacement. Such displacement measurement is useful in a number of
different environments, including currency dispenser systems. The reliability of currency dispenser systems, such as those employed i n
remote teller terminals, depends cricitally on
the accuracy in the monitoring of its performance.
Prior art monitoring systems mainly relied on
optically detecting a transition at the edge of a
document or detecting member. Thus, for instance, the IBM Technical Disclosure Bulletin, Vol.
7, No. 8 of January 1965 discloses a double document detector in which an arm connected to a pair
of rollers is moved by an extent dependent on the
thickness of the documents passing between the
rollers. A single document will move the arm to a
position in which it will not prevent light from
passing through an aperture to impinge upon a
light sensitive element but overlapped multiple
documents will move the arm to cover the aperture and block the passage of light thereby indicating an overlapped document condition. A disadvantage of this arrangement is that static
changes in the position of the rollers, caused by
wear, elasticity or accumulation of foreign matter,
may result in a drift of the operating range of the
system causing erroneous operation.
A unique method of accomplishing the monitoring function is disclosed in an international
application filed by the present Applicants on the
same day as the present application entitled
"Apparatus for Detecting the Passage of Multiple
Documents" (EP-A-0 042 860). In this application a translucent graded density medium or film
strip is attached to a mechanical arm, which arm
is displaced according to the thickness of a document or multiple documents passing between a
pair of rollers connected to the arm. Instead of a
single binary indication provided by the opaque
arm of the just mentioned prior art system, the
film strip causes an analog electrical signal to be
generated with an amplitude proportional to the
displacement of the arm. This ensures successful
operation of the system even when its operating
range is caused to shift slightly by reason of the
abovementioned changes in the position of the
rollers.
Disclosure of the Invention
It is therefore an object of the invention to fabricate a translucent medium which has an optical
density which constitutes an incrementally
changing gradient from dark to light.
It is a further object of this invention to provide
an inexpensive and simple method and apparatus
for producing a graded density medium.
Thus, according to the invention there is provided a method for fabricating a translucent
graded density medium, characterized by the
steps of providing a source of radiant energy; diffusing radiant energy from said source; passing a
portion of said diffused radiant energy through an
aperture; further diffusing said radiant energy
passing through said aperture; causing a portion
of said further diffused radiant energy to be reflected from a substantially opaque surface in
such a manner that the intensity of said reflected
radiant energy decreases as a function of the distance from the edge of said aperture; and focusing said radiant energy passing through said
aperture and said reflected radiant energy in the
plane of a radiation-sensitive medium to produce
a medium exhibiting an incremental gradient in
optical density across an area thereof.
According to another aspect of the invention,
there is provided an apparatus for fabricating a
translucent graded density medium, characterized by a source of radiant energy; a first diffusing means positioned to intercept said radiant
energy from said source; an opaque element
covering said first diffusing means, which element contains an aperture; a second diffusing
means, having an edge which overlies an edge of
said aperture in said element to cause a portion of
said radiant energy passing through said aperture
to be directed against said opaque element and
reflected therefrom; and means for selectively
exposing a radiation-sensitive medium to radiant
energy passing through said aperture to cause
the exposed medium to exhibit an incremental
gradient in optical density across an area thereof.
It has been found that by using the method and
apparatus of the present invention it was possible
to obtain a translucent medium having an optical
density which constitutes a substantially linearly
changing gradient from dark to light.
Brief Description of the Drawings
One embodiment of the invention will now be
described, by way of example, with reference to
the accompanying drawings, in which:
Fig. 1 is a front view of an apparatus according
to the present invention;
Fig. 2 is a fragmentary view of an aperture area
of the apparatus shown in Fig. 1;
Fig. 3 is a graph showing the density of a film
strip fabricated according to the present invention
with respect to the distance across the film strip;
Fig. 4 is a graph showing the output current of a
detector unit with respect to the distance across
several film strips which were exposed for different periods of time.
Best Mode for Carrying Out the Invention
Referring to Fig. 1, there is shown apparatus
comprising a photographic contact printing box
10 containing a tungsten lamp 12 at the closed
end. The open end of the box 10 is covered with a
ground glass diffusion plate 14, which plate is
positioned with its rough side facing away from
lamp 12. A sheet of black opaque photographic
paper 16 covers the rough side of plate 14 with
the exception of a narrow aperture 15, which is
1.27 centimeters wide, across the center of plate
14. A second ground glass diffusion plate 18 with
a thickness of 0.318 centimeters covers a portion
of paper 16, such that the right edge 17 of plate 18
overlaps the opening 15 of paper 16 an amount
sufficient to prevent light leakage between paper
16 and plate 18.
A camera 20, which may be a Polaroid type MP3 camera, is focused on the surface of paper 16 at
a distance which causes the length of the image
of the 1.27 centimeter wide aperture 15 of paper
16 to reach across the film 22 in camera 20. Film
22, which may be Polaroid type 55P/N film, is
chosen such that it produces a negative transparency when exposed, and eliminates the need
for external processing.
When camera 20 is activated, light from lamp
12 passes through plate 14, the aperture 15 in
paper 16, and plate 18 and exposes film 22, causing the area of film 22 corresponding to the 1.27
centimeter wide aperture 15 to be heavily exposed (dark on development). However, a portion
of the light from lamp 12 is diffused as it passes
through the rough surface of plate 14, as represented by path 19 in Fig. 2. The light is further
scattered by the rough surface of plate 18. As a
result, some of the light is reflected through edge
17 of plate 18 onto the surface of paper 16, and reflected therefrom. The amount of light which is
diffused onto paper 16 decreases rapidly as the
distance from edge 17 of plate 18 increases. Due
to surface reflectivity of paper 16, the light exposes film 22 in proportion to the distance from
edge 17. The resultant image on film 22 shows a
dark section corresponding to aperture 15, which
becomes lighter as the distance from the image of
edge 17 increases.
In the present embodiment, film 22 was exposed for a period of 105 seconds, creating a film
strip with the desired qualities for use in the aforementioned currency dispenser monitor. However,
the exposure time may be adjusted to generate a
film strip with the proper gradient for other
applications.
The graded-density film strip created in the
present invention can be an efficient means for
extending the operating range of a photodetector.
Some photodetector units, such as type H17B1
manufactured by General Electric, have an active
optical area of only 0.050 to 0.075 centimeters in
length. Therefore, any operating mechanism
which contains a sharp opaque-to-transparent
transition line can be moved only that distance to
control the detector. By using a graded-density
film strip to control the detector, the total range of
motion measurable by the detector can be expanded significantly.
Fig. 3 is a graph which plots the density as a
percentage of light transmission through a film
strip fabricated according to the method of the
present invention with respect to the position of
the film strip as measured by a microdensitometer. Fig. 3 shows that the percentage of light
transmission increases linearly as the distance increases from the point 23 on curve 24 when the
film portion being sensed is centered on the
transition line corresponding to the image of the
edge 17 of plate 18 (Fig. 1) on the film. As sensing
of the film is shifted toward and into the fully
exposed region, the percentage of light transmission rapidly decreases to a substantially constant
value.
The microdensitometer uses a precise reading
spot which is 0.028 centimeters in diameter, and
which provides a very accurate measurement.
However, when the film strip is used in conjunction with a commercially available detector, such
as the G. E. H17B1, the reading spot is significantly larger, which can have an effect on the
operating range. Fig. 4 is a graph which plots the
output current of a H17B1 detector with respect to
several film strips which were created using the
method disclosed in the present invention. Curve
28 shows the output current of the detector as a
function of the distance across a film strip from
the edge 17 image line (Fig. 1), where the film
strip was exposed for 105 seconds. Curve 26
shows the detector output versus a film strip with
a 90 second exposure time, and curve 30 represents the detector output plotted against a film
strip with a 120 second exposure. Referring to Fig.
4, it can be seen that the output current decreases
as the distance from the edge image is increased
for all the film strips, but that the relationship displays the best linearity in curve 28, using the 105
second time exposure. Also, the linear relationship covers a minimum of 0.254 centimeters,
which will allow for a significant expansion of the
total range of motion measurable by the detector.
It should be clear that many changes and modifications may be made without departing from
the scope of the invention as defined in the
appended claims. For example, a thin photographically sensitive glass plate may be used in
place of photographic film, or any source of
radiant energy may be substituted for the tungsten lamp.
1. A method for fabricating a translucent graded
density medium, characterized by the steps of
providing a source (12) of radiant energy; diffusing radiant energy from said source; passing a
portion of said diffused radiant energy through an
aperture (15); further diffusing said radiant energy passing through said aperture (15); causing a
portion of said further diffused radiant energy to
be reflected from a substantially opaque surface
(16) in such a manner that the intensity of said reflected radiant energy decreases as a function of
the distance from the edge of said aperture (15);
and focusing said radiant energy passing through
said aperture (15) and said reflected radiant energy in the plane of a radiation-sensitive medium
(22) to produce a medium exhibiting an incre-
mental gradient in optical density across an area
thereof.
2. A method according to claim 1, characterized
in that said radiant energy is light energy and in
that said medium (22) is a photographic film.
3. An apparatus for fabricating a translucent
graded density medium, characterized by a
source (12) of radiant energy; a first diffusing
means (14) positioned to intercept said radiant
energy from said source; an opaque element (16)
covering said first diffusing means, which element contains an aperture (15); a second diffusing means (18) having an edge (17) which overlies
an edge of said aperture in said element to cause
a portion of said radiant energy passing through
said aperture to be directed against said opaque
element and reflected therefrom; and means (20)
for selectively exposing a radiation-sensitive
medium (22) to radiant energy passing through
said aperture to cause the exposed medium to
exhibit an incremental gradient in optical density
across an area thereof.
4. An apparatus according to claim 3, characterized in that said first and second diffusing
means (14,18) each include a ground glass plate.
5. An apparatus according to claim 4, characterized in that each of said ground glass plates
has one rough surface positioned away from said
light source (12).
6. An apparatus according to claim 3, characterized in that said opaque element (16) is a black
sheet of photographic paper.
7. An apparatus according to claim 3, characterized in that the width of said aperture (15) is
approximately 1.27 centimeters.
8. An apparatus according to any one of claims
3 to 7, characterized in that said source (12) of
radiant energy is a light source.
1. Procédé pour fabriquer un milieu translucide
de densité graduelle, caractérisé par les étapes
consistant à utiliser une source (12) d'énergie
rayonnante; à diffuser de l'énergie rayonnante à
partir de ladite source; à faire passer une partie de
ladite énergie rayonnante diffusée dans une
ouverture (15); à diffuser encore ladite énergie
rayonnante ayant passé dans ladite ouverture
(15); à provoquer la réflexion, sur une surface
sensiblement opaque (16), de ladite énergie
rayonnante ayant encore diffusé de telle façon
que l'intensité de ladite énergie rayonnant réfléchie décroît en fonction de la distance du bord
de l'ouverture (15); et à focaliser ladite énergie
rayonnante passant dans ladite ouverture (15) et
ladite énergie rayonnante réfléchie dans le plan
dudit milieu (22) sensible au rayonnement afin de
produire un milieu dont une zone présente un
gradient incrémentiel de densité optique.
2. Procédé selon la revendication 1, caractérisé
en ce que ladite énergie rayonnante est de l'énergie lumineuse et en ce que ledit milieu (22) est un
film photographique.
3. Appareil pour fabriquer un milieu translucide
de densité graduelle, caractérisé par une source
(12) d'énergie rayonnante; un premier moyen
diffusant (14) positionné pour intercepter ladite
énergie rayonnante provenant de ladite source;
un élément opaque (16) recouvrant ledit premier
moyen diffusant, lequel élément présente une
ouverture (15); un second moyen diffusant (18)
comportant un bord (17) qui recouvre un bord de
ladite ouverture dudit élément pour qu'une partie
de ladite énergie rayonnante passant dans ladite
ouverture soit dirigée contre ledit élément optique et réfléchie par ce dernier; et un moyen (20)
pour exposer sélectivement un milieu (22), sensible au rayonnement, à de l'energie rayonnante
passant dans ladite ouverture afin qu'une zone du
milieu exposé présente un gradient incrémentiel
de densité optique.
4. Appareil selon la revendication 3, caractérisé
en ce que lesdits premier et second moyens diffusants (14,18) comprennent chacun une plaque de
verre dépoli.
5. Appareil selon la revendication 4, caractérisé
en ce que chacune desdites plaques de verre
dépoli présente une surface rugueuse éloignée de
ladite source de lumière (12).
6. Appareil selon la revendication 3, caractérisé
en ce que ledit élément opaque (16) est une feuille
noire de papier photographique.
7. Appareil selon la revendication 3, caractérisé
en ce que la largeur de ladite ouverture (15) est
d'environ 1,27 cm.
8. Appareil selon l'une quelconque des revendications 3 et 7, caractérisé en ce que ladite source
(12) d'énergie rayonnante est une source de
lumière.
1. Verfahren zum Herstellen eine durchscheinenden Mediums abgestufter Dichte, gekennzeichnet durch die Schritte: Vorsehen einer Strahlungsenergiequelle (12); Zerstreuen der Strahlungsenergie von der Quelle; Hindurchlassen eines Teils der zerstreuten Abstrahlungsenergie
durch eine Öffnung (15); weiteres Zerstreuen der
durch die Öffnung (15) laufenden Strahlungsenergie; Bewirken einer Reflexion eines Teils der
weiter zerstreuten Strahlungsenergie an einer im
wesentlichen undurchsichtigen Fläche (16) so
dass die Intensität der reflektierten Strahlungsenergie als Funktion des Abstandes vom Rande
der Öffnung (15) abnimmt; und Fokussieren der
durch die Öffnung (15) fallenden und der in der
Ebene des strahlungsempfindlichen Mediums
(22) reflektierten Energie, um ein Medium zu erzeugen, das einen inkrementalen Gradienten in
der optischen Dichte über eine Fläche auf dem
Medium aufweist.
2. Verfahren nach Anspruch 1, dadurch
gekennzeichnet, dass die Strahlungsenergie
Lichtenergie ist und dass das Medium (22) ein
photographischer Film ist.
3. Einrichtung zum Herstellen eines durchscheinenden Mediums mit abgestufter Dichte, ge-
kennzeichnet durch eine Strahlungsquelle (12);
eine erste Zerstreuungsvorrichtung (14), die
angeordnet ist, um die Strahlungsenergie von der
Quelle aufzufangen; ein undurchsichtiges Element (16), das die erste Zerstreuungsvorrichtung
bedeckt und eine Öffnung (15) besitzt; eine zweite
Zerstreuungsvorrichtung (18) mit einer Kante
(17), die über eine Kante der Öffnung in dem Element liegt, um zu bewirken, dass ein Teil der
durch die Öffnung laufenden Strahlungsenergie
auf das undurchsichtige Element gerichtet und
von diesem reflektiert wird; und durch eine Vorrichtung (20) zum selektiven Aussetzen eines
strahlungsempfindlichen Medium (22), der durch
die Öffnung laufenden Strahlungsenergie, um zu
bewirken, dass das bestrahlte Medium einen
inkrementalen Gradienten in der optischen Dichte
uber eine Fläche des Mediums aufweist.
4. Einrichtung nach Anspruch 3, dadurch gekennzeichnet, dass die erste und zweite Zerstreuvorrichtung (14, 18) jeweils eine geschliffene
Glasplatte aufweisen.
5. Einrichtung nach Anspruch 4, dadurch gekennzeichnet, dass jede der geschliffenen Glasplatten eine rauhe Oberfläche besitzt, die von der
Lichtquelle (12) abgewandt ist.
6. Einrichtung nach Anspruch 3, dadurch gekennzeichnet, dass das undurchsichtige Element
(16) ein schwarzes Blatt von photographischem
Papier ist.
7. Einrichtung nach Anspruch 3, dadurch gekennzeichnet, dass die Weite der Öffnung (15)
anähernd 1,27 cm ist.
8. Einrichtung nach einem der Ansprüche 3 bis
7, dadurch gekennzeichnet, dass die Strahlungsenergiequelle (12) eine Lichtquelle ist.