Note: Descriptions are shown in the official language in which they were submitted.
1139~365
Reference is made to a copending Canadian Serial No.
283,078, entitled Microprocessor Controlled Roll Film
Microfiche Reader, filed on July 19, 1977 by Delmar
Johnson, John R. Flint, Thomas Wells, Rolf Erikson and
Bruce Rady, and assigned to the assignee of this invention.
This invention relates to microfilm readers,
printers, and reader/printers and more particularly to means
for transporting a roll of film through such devices,
whether separate or combined. However, certain aspects of
the invention also find utility anytime that it is necessary
or desirable to transport long webs or strips, such as film,
magnetic tape, perforated tape, or the like. Therefore, the
term "reader/printer" is to be construed broadly enough to
cover all of these and equivalent devices, both combined and
separated. Likewise, the terms "film, web, or strips" are
to be construed broadly enough to cover any medium which
may be transported in the inventive manner.
A microfiche is a well known photographic device
wherein a plurality of images are micro-photocopies arranged
in an orthogonal array, on a small card or sheet film.
Therefore, the cards may become lost, damaged, destroyed, or
refiled out of order. Sometimes, microfiche contain in-
formation which must be continuously updated as the
recorded information becomes obsolete or is superseded. If
a large file of microfiche must be updated on a continuous
basis, a substantial amount of time and labor is required,
and filing mistakes are often made. Moreover, there are
costs in copying and manipulating the individual cards or
sheets of film, which costs are not incurred when copying or
manipulating rolls of film.
P ~ ~,
~i39E~65
Yet another problem centers about security and
control over a microfiche file. There are many times and
conditions when a company, for example, wishes to issue a
new edition of a microfiche "file" card, with an
assurance that it will be properly filed and used by all
employees, who are located at many widely scattered
points. Also, the company would want to preclude un-
authorized removal of individual microfiche from a company
~ file. There may be confidential information on some of the
microfiche and the company may not want to have it readily
available for copying.
Still another consideration is existing customer
habits. For example, a service or repairman conventionally
has a number of very large books containing pictures of
assemblies and long listings of parts for those assemblies.
If these books are reproduced on microfiche, the arrange-
ment of the microfiche should be such that the service or
repairman may substantially follow his existing habit
patterns, when using his books.
The reader/printer has an automatic call up feature
so that any given photographic area may be selected and
projected responsive to the push of a botton or the
operation of any other suitable switch. An electronic
control circuit, such as a microprocessor automatically
controls the movement of a film transport mechanism to
position a selected photographic area in a viewing area.
There, it is held stationary, while a lens is manually
moved to project a selected image in the microfiche
format.
---`` ii39865
The invention in one aspect pertains to a micro~ilm
reader/printer having a viewing area for use with a web having
thereon photographic areas which are individually identified by
elongated codes including a series of marks with the elongated
dimension of the series of marks being aligned and positioned
along the edge of the web, and extending over a portion of the
length of the web, each of the codes being positioned adjacent
lndividually associated ones of the areas. Means are provided
for transporting the web over a path through the reader/printer
in either of two opposing directions which presents the marks
in series to any point along the path of web travel. At least
a pair of sensor means are located adjacent the path for indi-
vidually reading each of the codes in series as the web is being
transported adjacent the sensor means, the sensor means reading
the code responsive to transport of the web in either of the
two directions. Means responsive to code reading by one sensor
means under the control of the other sensor means is provided
for storing a code identifying a photographic area on the wek,
and there are means for indicating a selected code. Comparator
means jointly responsive to the codes read by the sensor means
and the code-indicating means is provided for`comparing the
sensed and indicated codes, and means provide for reversing the
direction of web transport responsive to the comparing means
detecting a change in the relationship between the compared
codes which indicates that the desired photographic area has
passed the viewing area, a function performed by at least one
of the sensor means reversing each time that the direction of
web travel reverses.
The invention also comprehends in one aspect a process
for using a microprocessor to control a reader/printer having a
viewing area for use with strips of film, each strip of film
having thereon a plurality of photographic areas and each photo-
~ ~39865
graphic area being individually identified by an elongatedseries of code marks sequentially formed, the elongated dimen-
sion of the series extending along and parallel with the
length of the film. The process includes transporting the
strips of film in either of two directions through the reader/
printer; and sensing in series each mark of the codes on the
film at each of two separated positions as the film is being
transported in either of two directions through the reader/
printer, the sensing at one of the two positions a function
of sensing at the other of the two positions, and the sensed
series of marks being inverted when the film is transported
in one of the two directions. The process further provides for
indicating a selected code for identifying a selected one of
the photographic areas on the film, comparing the sensed and
indicated codes to determine the direction which the film
should be transported through the reader/printer in order to
reach the selected one of the photographic areas, reversing
the direction of film transport responsive to the comparison
indicating that a change of transport direction is necessary
to bring the selected photographic area into the viewing area
and reversing the function performed in at least one of the
two sensing positions responsive to each transport reversal.
Various other aspects of this invention will become
apparent from the description of the preferred embodiment
herein.
:
~'
~ 39~6S
A preferred embodiment of such a reader is shown
on the attached drawings wherein:
Fig. 1 is a perspective view of a roll film micro-
film reader, printer, or reader/printer, incorporating the
principles of the invention;
Fig. 2 is a schematic layout of a ~leb or strip of
roll film,h~vinga plurality of photographic areas, each in
a microfiche format comprising an ort~ogonal arr~y of imageS
with a special bar code printed along an edge of the film
and located near the photographic area which i~ identifies;
Fig. 3 show~ an exemplary bar code used to identify
each photographic area on the roll;
Fig. 4 is a graphical representation of how the bar
codé is read;
Figs. 5 and 6 graphically represent the transport
movement as the film is driven, reeled, and then brought to
a stop;
Fig. 7 is a block diagram of an electronic system
for controlling the microfilm reader/printer of Fig. l;
FigO 8 is a logic diagram of a control circuit used
to complete the block diagram of Fig. 7;
Fig. 9 is a speed vs. torque graph which illustrates
how the film is brought up to speed without loss of tension;
Fig. 10 is a graph which helps to illustrate how a
tension is maintained in the film;
Fig. 11 is a block diagram of the logic portion of
the control circuit;
Fig. 12 is a graphical representation of how the
same information is stored regardless of the direction in
which the film moves, appearing with Figs. 9, 10, 13, 14
and 15;
i398~S
Fig. 13 graphically illustrates how current is
increased to cause the film transport mechanism to initiate
film movement, appearing with Figs. 9, 10, 12, 14, and 15;
Fig. 14 is a logic circuit which illustrates how
three sensors may be arranged to detect the direction of
film movement, appearing with Figs. 9, 10, 12, 13 and 15;
and
Fig. 15 graphically and schematically illustrates
the three sensors of Fig. 14 and also shows a truth table
explaining the operation thereof, appearing with Figs. 9,
10, 12, 13 and 14.
Fig. 16 illustrates the differences between regular
bar codes and an overflow or "plus 1" bar code;
Figs. 17-19 are three timing curves (similar to
Fig. 4) for illustrating how the sensors read the three
bar codes of Fig. 16;
Fig. 20 is a truth table for the three timing
curves of Figs. 17-19; and
Fig. 21 is a logic diagram of a "plus 1" control
circuit.
Briefly, the reader, printer, or reader/printer
(Fig. 1) comprises a hood 50, a film transport mechanism 51,
and a control panel 52. The hood 50 includes a rear il-
luminated screen 54, in front of a cavity large enough to
sustain a beam of light which contains the projected micro-
film image on a single photographic area.
The transport mechanism includes a supply (relative
to forward film transport) roll or reel 56, a take up roll
or reel 58 and a web or length of film 60 extending there-
between. Preferably the reels 56, 58 have spools, hubs, orfilm cores with as large a diameter as possible so that
there will be a minimum of internal working within the web
1139865
or film 60, itself. Any suitable number of guide rollers
may also be provided (as shown at 62, 64) to convey the film
60 smoothly and evenly through the reader/printer. As the
film travels between rollers 62, 64, it passes between two
flat glass plates 66, 68 (usually called "glass flats")
which are closely spaced to hold the film, and therefore the
microfilm images, at a precisely positioned, vertically
oriented location relative to the lens system (not seen in
Fig. 1).
In order to load a web or strip, such as film 60,
into the reader/printer of Fig. 1, the web or strip is
pulled from the hub, reel, or core 56, passed over roller
62, between the glass flats 66, 68, over rollers 64, and
attached to the hub, reel or core 58. The hùbs, reels, or
film cores are internally keyed so that they will not fit
over spindles located in the cavities 70, 72, unless they
are properly positioned and the strip or film is properly
oriented.
Cover plates (not shown) may be provided to prevent
accidental removal of the film and to prevent entry of dirt
or other foreign matter into the cavities 70, 72. For
security, these cover plates may be protected by a lock and
key.
The control panel 52 includes a photographic area
address selector in the form of a plurality of push buttons
74 and a rotary switch 76. The rotary switch may be turned
to select the address code of a book and the push buttons
may be operated to select an address code of a chapter in
that book. In the example of a large service parts center,
the book might be "lawn mowers" and the chapter might be
"engines". Therefore, the switches 76, 74 may be marked
directly with these words. This way, the service or
~i39~6S
repairman using the reader/printer may ~ollow his customary
procedures of selecting book and chapter, which procedures
he conventionally followed before he received the microfilm.
Any other additional control, such as switch 75,
may be provided to switch the reader/printer or lamp off/on
or to cause any other suitable functions.
Once the photographic area representing a book and
chapter has been automatically delivered to a reading and/or
printing or viewing position, it remains stationary. The
operator grasps a handle 77 and moves it over an index
printed on plate 78. When handle 77 reaches a selected
point, a desired index on the plate 78 appears in a window
80 associated with handle 77, and a corresponding page or
image on a photographic area on film 60 is projected onto
the reader/printer screen 54.
A special "Plus 1" push button 81 is provided to
extend the chapter by advancing the film transport to display
the next photographic area, when a chapter contains an over-
flow of information wherein more than one of such areas is
identified by a single chapter address code. When the film
reaches the last overflow or "plus i" photographic area in a
chapter, the roll of film automatically rewinds to again
present the first photographic area at the address of the
selected chapter, if the "plus 1" button 81 is again pushed.
A thumb wheel 82 on handle 77 may be turned to focus
the image projected onto the screen 54.
Fig. 2 shows a small section of film 60 and illus-
trates how the photographic areas are arranged thereon and
identified by bar code addresses. In greater detail, each
photographic area (85, for example) may have any convenient
length "L" and a width "W", approximately equal to the width
of the film, with suitable allowance for margins. Each
139~36S
photographic area includes a number of individual images
(one of which is outlined at 86 for easy identification).
The images on the photographic area are arranged in an
orthogonal layout. A suitable index or table of contents
may be provided near one edge of each photographic area, as
indicated by cross hatching at 88.
The drawing has been marked at 90, by way of
example, to indicate that the images on photographic area 87
are identified by the address "Book 6, Chapter 9", which is
also indicated by the bar code 92 address. The letter "A"
on photographic area 85 implies that chapter 9 is so large
that it overflows and extends over a plurality of photographic
areas. The user realizes that he must go on to another or
overflow photographic area and he pushes the special "plus 1"
push button 81 (Fig. 1) to cause the reader/printer to
advance from photographic area 87 to overflow photographic
area 85, where a special single mark bar code 89 is en-
countered. If the "plus 1" push button 81 is pushed again,
the transport advances a second time, looking for another
single mark bar code. However, this time a standard bar
code 91 is found. Therefore, the second operation of the
"plus 1" push button 81 causes the film to briefly rewind
and to again display the initial photographic area 87 in
Chapter 9. This "plus 1" process of advancing to the next
or overflow photographic area, one at a time, may be re-
peated as often as required.
A series of bar code addresses (such as 89, 91, 92)
is printed along one margin of the film and precisely
located at the same relative positions near each photographic
area. Therefore, if the bar code 92, for example, is
precisely positioned by the film transport mechanism so that
a sensor is at one edge, such as 93, of the code 92, the
V 9
" 1~39865
photographic area 85 is precisely located in the viewing
area or in the optical path of the reader/printer.
The nature and function of the bar code is shown in
Fig. 3. There are a number (here nine) of spots or marks
arranged in a series and in a distinct geometry. Each
binary "1" is a wide spot or mark, as at 98, and each "0" is
a narrow spot or mark, as at 100. Each wide spot 98 is
exactly twice as wide as a narrow spot 100. A pair of
sensors or transducers 104, 106 are positioned adjacent the
edge of film 60 to read the bar code as the film passes
adjacent them. For example, if the spots or marks 98, 100
are dark areas recorded on transparent film (or transparent
marks on dark film), the sensor or transducersl0~-, 106 ma~
include light sources on one side of the film and photocells
on the other side of the film., The width of the space 107
between each spot or mark is exactly the same as the width
of a narrow spot 100. The sensors or transducers 104, 106
are separated by a distance 108 which is exactly equal to
1.5 times the width of a narrow spot or mark 100.
According to the invention, it is totally irrelevant
whether the film travels from left to right or from right to
left. Neither direction is preferred. However, it is
convenient to have an expression for distinguishing between
these two directions. Therefore, one direction is arbitrari-
ly called "forward" and the other "reverse". This same
arbitrary terminology is used to identi~y "forward" and
"reverse" motors which drive the film in those respective
directions.
It should be noted that B sensor or transducer 104
encounters the bar ¢ode 92 before the A sensor or transducer
106 encounters it, when the film travels in a forward
direction. The A sensor encounters the bar code first when
1~ 10
1139865
the film travels in the reverse direction. There is no
problem, however, since the recording sensor drives into one
side of a shift register when film moves in one direction
and into the other side of that same shift register when film
moves in an opposite direction. The shift register marks the
same output conductors responsive to the same code, regardless
of which direction the film is driven.
Fig. 4 graphically shows how the outputs of the
sensors or transducers are interpreted by the associated
electronic control circuits. (There is no correlation
between the codes of Figs. 3, 4.) The sensor output pulse
109 is wide, responsive to a wide spot or mark. A narrow
spot or mark 100, produces a narrow pulse 110, and a space
107 between spots or marks are indicated by narrow spaces
111 between pulses. The relative widths of the pulses and
spaces, and of the distance between the sensors or trans-
ducers are indicated in Fig. 4 by "X", "2X" and "1.5X".
Each bar code has a guard zone 112 on one end, in which zone
another bar code is forbidden. At any distance beyond the
end of this guard zone which is greater than 2X (i.e., more
than a wide spo~ or mark), a new bar code may begin. There-
fore, a photographic area does not have to have a fixed and
standard length. There is no need for a guard zone on the
other end of the bar code because that space is protected by
the next adjacent bar code.
The output of sensor or transducer B is shown by
curve B of Fig. 4 and the output of sensor or transducer A is
shown by curve A. Note that the output A is the same as the
output B, except that there is a lag of 1.5X between the
two outputs. If the direction of film travel is reversed,
the pulses in curve B will lag after those in curve A,
because the sensor A encounters the bar code before sensor B
encounters it in reverse film travel.
11
-`"` il3986S
The A sensor functions as a clock or strobe for
reading the B sensor. This way, it is not necessary for a
clock to maintain a precise synchronization between the film
transport and the code reader/printer. In greater detail,
curve A has been marked with arrow heads to indicate whether
the transitions in the output of sensor or transducer A are
going positive or going negative. In this example, the
associated logic circuitry is arranged to read the output of
the B sensor or transducer, each tlme that the transition in
the output of the A sensor or transducer is going positive,
as at 117, for example. Curve B is marked at the left-hand
end to indicate the voltage levels representing a "1" and a
"0" .
By inspection, it will be seen that curve C re-
presents the state of the output of the B sensor or trans-
ducer, at the instances when the positive going transitions
occur in the output of the A sensor or transducer. Thus,
the logic circuitry "sees" the binary word "101100", as
indicated by Arabic numerals below curve C. By recalling
that each wide pulse in curve B is a binary "1" and that
each narrow pulse is a binary "O", it is apparent from an
inspection of Fig. 4 that the code originally read by the B
sensor or transducer has been correctly interpreted by the
logic circuitry.
Curve D is a parity envelope generated as a function
of the start and stop of a bar code. This envelope is
generated responsive to the negative going transitions in
the output of the A sensor, under the clocking assumptions
of Fig. 4. The first negative going transition 113 in the
output of the A sensor or transducer triggers a start of a
code detection parity envelope, as indicated at 114 in curve
D. As long as the A sensor goes negative while the B sensor
1139865
is "high", bar code continues to be read from the film.
Hence, the partiy control envelope, curve D remains "high".
When the negative going A sensor output occurs while the B
sensor is "low", the parity envelope collapses or terminates,
at 116. At this time, a negative going A sensor transition
counter reaches a specific count if there is code parity.
The sensors should have read the last output in a bar code
if the negative going transition 115 occurs while the B
curve is low, which indicates an end of a bar code. The
curve D goes from "high" to "low", as indicated at 116. The
end of code signal 116 occurs on the sixth negative going
transition (curve A) in Fig. 4 or the ninth transition in
the code of Fig. 3. Since the number of spots or marks are
the same in all bar codes, there is a parity check because
the proper number of spots or marks must be registered at
the time when curve D goes negative. (In the example here
given, the parity check occurs when the circuit counts the
correct number of down going transitions between edges 114,
116, inclusive.)
There are several ways that clocking may be done,
when the film reverses its direction of travel. One way of
clocking is to cause the lagging sensor to always act as a
clock for the leading sensor. This way, the two sensors
interchange their respective functions when the film trans-
port reverses the direction of film travel. Another way of
clocking is to cause the normal output of one of the sensors
to act as a clock when film moves in one direction and a
complement of that output to act as a clock when the film
moves in an opposite direction. Regardless of which of these
clocking systems is used, care should be taken to insure that
there is a uniform and consistent parity check envelope
(curve D) for a full and complete bar code, regardless of
the direction of film travel.
13
~13986S
The advantage of interchanging the roles of the two
sensors is that the parity envelope (Fig. 4D) is automatically
the same, regardless of the direction of film travel. The
leading edges of the trailing sensor pulses always test the
status of the leading sensor, for the reading of a binary
signal. The trailing edges of the trailing sensor pulses
always test the status of the leading sensor for generating
the parity envelope. In the complementary method of parity
- checking, the leading edges of the trailing sensor pulses
test the status of the leading sensor, for reading a binary
signal in the forward film travel direction. For reverse
film travel, the trailing edges of pulses from the leading
sensor test the status of the trailing sensor for reading a
binary signal. The parity envelope on reverse travel will
require a reversal of the roles so that the trailing sensor
will test the leading sensor in order to trigger the col-
lapse of the parity envelope.
The film is transported responsive to an operation
of switches on control panel 52, to automatically select
and display a desired photographic area. More particularly,
Figs. 5, 6 help explain how a roll of film is transported,
in order to bring a selected photographic area into the
viewing area in the reader/printer of Fig. 1 responsive to
a reading of the bar codes of Figs. 2-4. Fig. 5 graphically
shows film 60 travelling a forward direction and Fig. 6
shows the same film 60 travelling in a reverse direction.
The memory of the last read bar code is stored, so
that the reader/printer always starts in the correct
direction. But, if that memory has been lost (for example,
there might be a power interruption), the reader/printer
starts in one preferred direction. One bar code is read,
and the electronic control circuit decides whether the film
14
~ ~39~365
is or is not travelling in the correct direction. If it is,
the film continues to so travel. If not, the film trans-
port reverses direction.
It should be noted that every code is checked, while
it is being read, to determine whether it is greater or less
than the desired code. ~ence, the direction of film travel
is reversed whenever a code indicates that it is travelling
in the wrong direction.
In either direction of travel, it is always
necessary for the film to stop at the same position relative
to the bar code. For example, as Figs. 2 and 3 are drawn,
it is desirable for the film to always stop with the A
sensor or transducer head 106 (Fig. 3) aligned with the
left hand edge 93 of the bar code 92, regardless of whether
the film travels in a forward or reverse direction.
Fig. 5 shows how the film is so stopped from the
forward travel motion, 184. Initially, the film transport
is commanded to travel at a high searching speed. When the
control circuit first recognizes a bar code corresponding to
its commanded code, the film transport may be travelling at
a very high speed if it has been running long enough to get
up to its maximum speed. Since the transport mechanism is a
mechanical device with inertia, the film 60 may coast one or
more bar codes beyond the desired photographic area. The
transport reverses direction 186, and it thereafter travels
at a slow speed. When the desired bar code is again
recognized, the transport reverses once more. At slow
speed, inertia does not carry the transport as far as it
does at high speed. However, the film may still coast by
at least some discrete distance.
1~398~5
During this homing sequence, the deceleration is
always greater than the acceleration, each time that the
film transport reverses direction; thus, coasting becomes
progressively smaller, as graphically indicated by the
lengths of arrows in Figs. 5, 6. Therefore, the transport
mechanism reverses (188) direction a number of times (here
up to six times), moving the film slightly less on each
reversal, until the leading edge 93 of the bar code is
precisely under the A sensor or transducer head 106 (i.e.,
at the point 115 in Fig. 4). Accordingly, the edge 93 moves
back and forth under sensor A in diminishing amounts of
travel. After a certain number of reversals have occurred,
the homing sequence is complete and the film is positioned.
When the film is travelling in the reverse direction
(Fig. 6), the control circuit again looks for a bar code
corresponding to its command code. However, it would be
expensive and awkward to require the homing to be performed
in two different ways depending upon the direction of film
travel during high speed searching. Therefore, once the bar
code corresponding to the command code is encountered during
high speed searching in the reverse direction 189, the
transport mechanism reverses its direction of travel without
immediate effect and before the homing sequence begins.
This means that even on reverse direction searching, the
film is travelling in forward direction 184 when the homing
sequence is initiated. Thereafter, the homing sequence is
the same as the sequence used in the forward direction.
The electronic control circuit is seen in Figs. 7,
8. Briefly, the rotary and push-button switches 74, 76
(Fig. 7) send the command code signals into a microprocessor
192, which may be any of many commercially available products.
16
1139865
While any of these products may be used, the invention
currentiy employs the well known F8 microprocessor system
components made by the Fairchild Camera & Instrument
Corporation.
The A,B sensors or transducers 106, 104 transmit
the sensed signals (Fig. 4) into the microprocessor 192 via
switching amplifiers 194, 196. The microprocessor energizes
a glass flat solenoid 197 via a driver amplifier 198. The
microprocessor controls the direction of film travel by
selectively energizing "FWD", "GO" and "REV" wires 200. The
"FWD" and "REV" wires are energized with a steady d.c.
potential to select the direction of film transport travel.
The "GO" wire is energized with either a steady d.c. poten-
tial to command the forward (F) and reverse (R) motors 202,
204 to turn at high speed or with an interrupted d.c.
potential to command the motors to turn at a low speed. The
actual low speed depends upon the percentage of a duty cycle
during which the GO wire is marked with the interrupted d.c.
potential. These command signals are fed to the motors
202, 204 via two individual driving amplifiers 206, 208,
which are essentially "AND" gates.
Each of the motors 202, 204 is mechanically con-
nected in any suitable manner to drive one of the associated
film cores. Forward motor 202 drives the take up film core
58 (Fig. 1) and reverse motor 204 drives the supply film
core 56.
Fig. 8 shows the logic diagram of an electronic
control circuit which may be used to complete the block
diagram of Fig. 7. The control switches 74, 76 are part of
a matrix 212.
il39~6S
The matrix 212 comprises horizontal and vertical
multiples defining a plurality of crosspoints. Each switch
74, 76 has a set of contacts connected across the matrix
crosspoints. For example, one set of switch controlled
crosspoint contacts, shown at 209, are here assumed to be
the only ones closed by an operated push button 74. of
course, any other crosspoints could also be the closed ones.
Scanner 210, which may be part of the micro-
processor, initially applied ground G to the uppermost
horizontal Hl in matrix 212. All other horizontals are
marked with the positive potential Pl. All verticals are
marked with positive potential P2.
Scanner 211, which may also be part of the micro-
processor, sequentially tests the potential on each vertical
in matrix 212, and finds only potential P2 because the above
assumption, in this description, has been that only cross-
points 209 are closed.
After scanner 211 completes one scan, the scanner
210 is operated to remove ground G from the uppermost hori-
zontal Hl and to apply it to the next lower horizontal H2.The scanner 211 finds potential P2 on vertical Vl. However,
vertical V2 is connected through contacts 209, assumed to be
closed, to ground G.
Immediately, the control circuit recognizes that it
has found the closed push-button contact and scanner 210 is
advanced in its cycle to apply ground G to horizontal HS.
Again, the scanner 211 searches for a ground applied through
a selected set of contacts on rotary switch. If the closed
rotary switch contact is on horizontal HS, the control
circuit stops the scanners. If not, scanner 210 is advanced
to apply ground G to horizontal H6 and scanner 211 searches
for it. One way to prevent contact bounce is to require the
~13986S
scanners to find the same contact closure a predetermined
number of times before accepting the signal as a valid one.
It should now be apparent that the matrix 212 en-
ables the electronic circuitry to ascertain the commanded
code responsive to a selective operation of a push button
74 and rotary switch 76.
The logic of the microprocessor 192 is represented
- at 214 (Fig. 8 and shown in detail in Fig. 11). For com-
pleteness both Fig. 8 and Fig. 11 repeat the sensors or
transducers 104,106 and amplifiers 194, 196. Each of the
sensor amplifiers 194, 196 include a buffer amplifier 216,
218 (Fig. 8) followed by individually associated trigger
circuits 220, 222, preferably Schmitt triggers. This way,
the logic ciruitry 214 receives unambiguous sensor originated
signals (Fig. 4) responsive to each detection of a bar code
spot or mark.
The remainder of Fig. 8 shows a circuit for driving
the film transport mechanism and for maintaining fllm
tension. This portion of the figure is divided by a dot-
dashed line 224, with the driving amplifier 206 shown above
the line and driving amplifier 208 shown below the line.
Since circuits 206,208 are the same,only circuit 206 will be
explained.
The forward FWD and reverse lines REV are con-
nected to individually associated AND gates 226, 228. Thus,
the AND gate 226 conducts when the microprocessor 192 ener-
gized the FWD and GO wires. The AND gate 228 conducts when
the microprocessor energizes the REV and GO wires.
The output of AND gate 226 is fed into an OR gate
230 which energizes a motor drive circuit 232. The motor
drive circuit supplies a d.c. voltage to forward motor 202.
19
365
If the motor 202 is in the fast drive mode, there is a
steady state d.c. potential. The microprocessor 192 ener-
gizes the GO wire continuously and without interruption.
Drive circuit 232 then applies a maximum d.c. power to the
motor 202, which runs at high speed.
When the desired bar code is detected, the motor
202 is stopped. The microprocessor signal for stopping the
motor is a simultaneous energization of the FWD, REV and GO
wires, so that the two motors pull against each other. The
potential on the GO wire is interrupted, first slowly and
then at a progressively faster rate. After the frequency of
interruptions passes a critical high frequency rate, the
system can no longer follow the interruptions and the motors
stop with the initially undriven motor acting as a drag upon
the film to maintain film tension and help stop the driven
motor.
When the motor 202 is driven in a slow drive mode,
there is a problem since frictional forces may vary from
system to system, with the amount of film which has been
wound upon the driven reel, etc. For the same slow speed,
the amount of energy supplied at any given time may vary
from the amount that must be supplied at any other time.
Accordingly, when the combination of signals sent ~rom the
microprocessor logic 214 over the FWD and GO leads to motor
drive circuit 232 indicates a slow speed, the motor drive
circuit 232 preferably applies energy to the motor in the
manner indicated by Fig. 9, wherein speed is shown on a
vertical scale and torque on a horiæontal scale. Initially,
a very slow voltage is applied to forward motor 202 a-t a
potential which is here arbitrarily designated "X". If the
motor does not turn, the potential is gradually increased to
"X2". If it still does not turn, the voltage is increased
ii39865
to "X3", etc. ~ventually, the motor be~ins to turn.
In order to so increase the potential applied to
the motor 202, the slow speed indicating intermittent inter-
ruptions on the GO wire begin as narrow pulses which are
gradually made wider, with a rising ramp front characteristic.
As the GO wire is energized during progressively longer
period in the interruption duty cycle, the motor 202 runs at
progressively faster (but still relatively slow) speeds.
Hence, as soon as the instantaneous friction is overcome in
the motor, it starts slowly and thereafter builds speed,
with the accelteration characteristics depicted by line 233
in the graph of Fig. 9.
Whenever either motor (the driven motor) is oper-
ating to pull the film, the other motor (the undriven motor)
is energized with a weak current. The undriven motor
supplies only enough torque to act as a drag and thereby
maintain film tension. The control of this drag is extremely
important since it maintains a uniform film tension. Other-
wise, the turns of film on a reel might alternately loosen
and cinch, and therefore, damage the film. Accordingly,
there is a need for the microprocessor to precisely control
the current supplied to the undriven motor.
Fig. 10 explains how the current supplied to the
undriven motor is controlled and regulated to maintain a
predetermined film tension. In greater detail, when the
forward motor is first energized, it draws current which
shoots up from a zero axis to the point 240, Fig. 10A. As
the motor begins turning, the current falls off, with some
decaying characteristics, as indicated between the points
240, 242.
il39~6S
Current sensor 24~ is a trigger circuit connected
to the output of the motor drive circuit 232 to detect
current drawn by the motor, as depicted in Fig~ 10A. The
sensor 244 detects when the current falls to the point 242,
and thereupon sends a signal over wire 250 to AND gate 252.
The other input of AND gate 252 is already energized via the
FWD wire and the output of AND gate 226. Thus, when the
forward motor 202 is operating, AND gate 252 applies a
signal through OR gate 254 to motor drive circuit 256 and
reverse motor 204.
Upon energization, reverse motor 204 acts as a
drag upon film 60 and therefore upon forward motor 202,
which must then draw more current from the motor drive
source 232. Current sensor 244 uses a trigger circuit
which switches OFF when there is an increase of current in
the motor 202~ The current to reverse motor 204 is removed~
Thus, the motor drive circuit 256 has received a pulse of
driving current, as indicated by pulse 258 (Fig~ 10B)~ A
de-energization of the reverse motor 204 reduces the drag
upon film 60 and foward motor 204, and the cycle repeats~
The motor drive circuit may also operate on an
analog basis, if desired.
Hence, as long as the dri.ven forward motor 202
continues running (Curve A, Fig. 10), its energizing current
fluctuates while motor 202 hunts for current film tension or
motor torque, as shown at 260. The undriven reverse motor
204 is pulsed, as shown at 262, responsive to current
fluctuations 260. Thus, the undriven motor receives a low
level d.c. energy, which is an integration of and derived
from an average of the pulses 262. This low level of current
causes the reverse motor 204 to resist turning and thereby
maintains a steady tension upon the film 60.
22
1139~36S
Between the outputs of AND gates 226, 228 there is
an interlock circuit designed to keep the motors from being
driven at any time when the mechanical parts of the reader/
printer are not in a condition for the film to travel
safely. In greater detail, a plurality of any suitable
mechanical switches 264 are connected in series between
ground and a voltage divider comprising resistors 266, 268,
270. These switches 264 may be "Microswitches" actuated by
mechanical reader/printer parts, such as the movable glass
flat 68 or any other mechanical parts, all of which should
be in a normal condition before the film may be safely
transported. If all of the switches 264 are properly
closed, ground is applied to the base of transistor 272,
which switches off. Thereafter, the outputs of AND gates
226, 228 may be effective upon the motors 202, 204. However,
if one or more of the interlock switches 264 is opened, the
potential set by voltage divider 266, 268, 270 establishes
a base bias which switches on the transistor 272, to apply
ground to a junction between diodes 274, 276, which are
connected to the outputs of AND gates 226, 228, respectively.
Thereafter, the outputs of AND gates 226, 228 are clamped
to ground, and the motors 202, 204 cannot be commanded to
operate.
When the electronic control circuit of Fig. 8
finally stops the film, a desired photographic area is
accurately positioned in a viewing position between the
glass flats 66, 68 (Fig. 11). More particularly, the bar
code reading head sensors or transducers 104, 106 are
located at any convenient point along the travel path for
film 60. For example, if the bar code 92 (Fig. 2) is
printed at a proper position on the film 60, photographic
area 87 is precisely positioned between glass flats 66, 68,
23
1139865
when one edge 93 (Fig. 2) of the bar code is directly under
one of the sensors (here assumed to be A sensor 106~.
Fig. 11 shows the basic principles of the logic 214
for the microprocessor 192 of Figs. 7, 8. Those components
which appear in Fig. 11 and other figures are identified by
the same reference numbers. The portions of Fig. 11 which
are not part of the microprocessor are enclosed within
blocks outlined by double dot-dashed lines. The operative
portions of the microprocessor are separated by dashed lines.
The basic or master control for the microprocessor
192 is a timed enabling device or allotter 300. It causes
each of a number of different functions to be performed in
an orderly sequence. As here shown symbolically, the
allotter is a clock having a single rotating hand 302 which
sequentially touches conductive segments 1-0 in order to
individually enable the various circuits shown elsewhere in
Fig. 11.
The allotter 300 steps periodically under control
of a free running oscillator (not shown~. The allotter 300
may be stepped forward or backward, depending upon control
signals sent from circuit 301. Normally, the hand of
allotter 300 is to be viewed as rotating step-by-step in
the clockwise direction D. However, each time that the
allotter hand 302 reaches segment 3, it automatically steps
backward to segment 2, responsive to the next pulse from the
- free running oscillator, unless gate 304 is inhibited.
Accordingly, the cyclic repetition of signals from the seg-
ments 2, 3 provides means for cyclically reading the com-
parator 336 and the A, B sensors 106, 104. When the com-
parator finds equality in the stored and read codes, the
cyclic reading is interrupted and a stopping sequence begins
when the allotter reaches the fourth segment. On the fifth
24
T7
il39~65
segment, the film comes to rest and the allotter stops to
hold the film in its stopped position. On the next command
to find a photographic area, the allotter steps over the
zero segment to restore all circuits to normal. Then the
sequencing begins again when the allotter reaches segment 1.
The other major subdivisions (set off by dashed
lines) of the circuit of Fig. 11 are the A and B sensor
circuits 306, 308, code input circuit 310, keyboard 312,
keyboard control circuit 314, debounce circuit 316, valid
code detect circuit 318, transport control circuit 320, find
mark circuit control circuit 322, and speed control circuit
324. A "plus 1" circuit 325 enables the film transport
mechanism to advance one photographic area section at a time,
as explained above in connection with the special bar code 89.
Means are provided for storing an address of a
desired photographic area responsive to an operation of a
selected key in the keyboard 312. In greater detail, the
instantaneous position of the allotter 300 determines the
sequence in which the various circuits operate. By inspec-
tion, it is seen that the first circuit to opera-te (i.e.,
responsive to a signal from allotter segment 1) is debounce
circuit 316. Responsive to a signal applied simultaneously
to a lower input of AND gate 326 and to a monostable flip-
flop 328, there is a period of time, indicated by pulse 330,
during which the flip-flop 328 is "high" at terminal Q and
"low" at terminal Q. Then, after pulse 330, the flip-flop
328 outputs go high at terminal Q, whereupon AND gate 326
conducts. The duration of pulse 330 is adequate for any
contact bounce to subside, in keyboard 312.
Responsive to an output from AND gate 326, an
enabling signal i5 applied to AND gate 332. If any switch
in keyboard 312 has been operated, a selected combination of
- 25
113g865
signals appears at the keyboard output terminals 334. These
signals pass through AND gate 332, when it is enabled from
the output of AND gate 326, after the end of the debounce
period.
Thus, the bar code address of the demanded photo-
graphic area is stored in a comparator 336 while the allotter
is on segment 1, according to the operation of a key in key-
board 312.
When the allotter 300 reaches segment 2, a series
of AND gates 338, 340, 342 are enabled, which commands the
transport mechanism to start reeling the film. The direction
of reeling depends upon information, if any, which may be
stored in the code input circuit 310 prior to an operation
of the key. It is here assumed that no information has been
stored previously. Therefore, the film transport mechanism
may begin reeling in either a forward or a reverse direction
(one preferred direction is usually built into the circuits).
Means are provided for reading the bar codes as the
film is reeled, responsive to the allotter reaching segment
3. Also, responsive to the allotter output from segment 3,
an AND gate 304 conducts to cause allotter 300 to step back
to segment 2, unless gate 304 is inhibited by a location of
the desired photographic area. Actually, the allotter is
operating at a suitable sampling speed and the film transport
is operating with mechanical inertia. Therefore, the film
runs smoothly and without interruption despite the allotter
switching back and forth between segments 2 and 3.
The A and B sensors 306, 308 and the circuits 194,
196 are connected in parallel with wires J and K which may be
used when a third sensor is employed to detect the direction
of film movement, as disclosed in Fig. 14. Normally, wires
J and K are not used.
26
^-` 11391~65
One embodiment of the reading principle was des-
cribed above in connection with Fig. 4. There, it was ex-
plained that one way of clocking is to interchange the roles
of the A and B sensors, depending upon the direction of film
travel. A second embodiment is shown and described in Fig.
12, comprising two graphical parts 346, 348, which refer to
film travel in reverse and forward directions, respectively.
It will be noted that Fig. 12 is drawn so that the positions
of sensors A, B, the bar code 92 and the clock symbols
(arrow heads) on sensor A output are reversed in these two
parts 346, 348. Upon reflection, it will be seen that these
drawing reversals amount to film travel reversal. In each
case, it may be assumed that either the bar code 92 moves to
the left (arrow E) or the sensors move to the right (arrow
G). This reversal symbology is here used so that the clock
pulses 350 may be shown in the graph with apparent movement
toward the right, since time is normally depicted by such
rightward movement.
When A sensor is first over a code mark area (e.g.,
mark 349) of bar code 92, there is an upward movement or
leading edge 352 in a graph of a pulse in the A sensor out-
put. When the A sensor moves off a code mark area, there is
a downward movement or trailing edge 354 in the output of
the A sensor. In the embodiment of Fig. 12, as distinguished
from the embodiment of Fig. 4, sensor A is always used as
the clock for reading the output of sensor B. The arrow
heads indicate when the output of the B sensor 104 is read
(i.e., on the leading edge 352 in forward direction and the
trailing edge 354 in the reverse direction). By inspection,
and recalling the description of Fig. 4, it is seen that the
output of the B sensor accurately reflects the binary
information embodied in the bar code 92, regardless of
whether the film is travelling in a forward or a reverse
direction. 27
il39~65
The code input circuit 310 (Fig. 11) provides
means for storing the bar code as it is read by the B sensor.
In greater detail, a shift register 356 has a clock input
358 controlled from A sensor 106 on either the leading or
trailing edge of the sensor A clock pulses, as indicated in
Fig. 12. The shift register 356 has an input 360, 361 con-- -
trolled by B sensor 104. The direction of film travel is
sensed at shift register 356 responsive to a signal on wire
362, which controls an exclusive OR gate 364 and which
selectively marks a shift left terminal SL. If the shift
left terminal SL is not marked, the shift register 356
shifts to the right.
The A sensor clocking of the shift register input
is controlled this way. When A sensor 106 is over a bar
code mark, amplifier 194 produces a pulse 366. For the
duration of such pulse, an inverter 368 (Fig. 11) switches
off its output so that AND gate 370 cannot produce an out-
put. Simultaneously, AND gate 372 is energized by pulse
366. If the film is travelling in a reverse direction,
wire 362 is not energized so that AND gate 372 conducts to
clock the A sensor pulses into shaft register 356 responsive
to the leading edge of pulse 366. However, if the film is
travelling in the forward direction, wire 362 is energized
to inhibit AND gate 372 so that there is no output responsive
to the leading edge of the A sensor pulse 366. In this
case, AND gate 370 conducts when inverter 368 switches its
output on responsive to the trailing edge of pulse 366
(i.e., when the individual code marks pass out from under
sensor A). Thus, as shown at 346 (Fig. 12), the clock
pulses from the A sensor are effective on the leading edge
when film travels in the reverse direction and on the trail-
ing edge when film travels in a forward direction. Either
28
113g865
way, the outputs of the gates 370, 372 are conducted through
OR gate 374 to an AND gate 376.
From Figs. 4 and 12, it will be recalled that the
mark (a binary "0") in the bar code is one unit wide while
the sensors are separated by one and one-half units. From
Fig. 12, the B sensor is always read on the leading or
rising edge 352 of the A sensor output for reverse film
travel and on the trailing or falling edge 354 for forward
film travel. A validity or parity check is made on the
edges (not marked by arrow heads) of the A sensor output
pulses which are opposite to the edges used for clocking.
Responsive thereto, the geometry of an envelope (curve D in
the various figures) of the bar code is compared with pulse
train produced. Care is taken to be sure that the geometry
of this parity envelope is identical for both directions of
film travel. Clocking on one edge and validity checking on
the opposite edge, effectively reduces the spacing between
the sensors so that at the time of validity checking, the B
sensor always has an output responsive to any mark in the
bar code, when it is read on the clocking edge.
Means are provided for checking the apparent
validity of the bar code, as read from the B sensor 104.
In greater detail, the A sensor 106 output is also applied
from OR gate 374 to a code validation circuit 318. Inverter
378 conducts at all times, except when there is an output
from OR gate 374. When there is an output from OR gate
374, the inverter 378 switches off. Hence, the effect of
inverter 378 is to read the edge of the A sensor output
pulse 366 which is opposite to the clocking edge of pulse
346.
The B sensor 104 feeds its output to the D terminal
of a memory circuit 380, which reads and remembers the
29
~ 1139~65
output of the B sensor each time that inverter 378 enables
a read in. As a result, the memory circuit 380 is set to a
"high" potential state for the duration of the pulse train
resulting, from a valid reading of ~he bar code by the B
sensor.
Responsive to the output potential at terminal Q
of memory circuit 380, a "high" potential is applied to the
"clear" input CLR of shift register 356. The small circle
or bubble 382 indicates that the "CLR" (or clear terminal)
is "low" when the memory output is "high". Thus, shift
register 356 may store the pulses received from B sensor
104.
However, if the B sensor 104 output does not recur
within the period permitted by the memory 380, there is an
interruption for a period which is long enough to cause the
output potential at terminal Q of memory 380 to go "low".
When this interruption occurs, the CLR terminal goes "high"
to erase the memory stored in shift register 356. The
result is that the shift register is cleared if an invalid
(less than a full complement) code is received or at the end
of a complete bar code, whichever occurs first. From a
comparison of Figs. 4 and 12, it will be seen that there is
a period of time equal to the width of the last A sensor
pulse (at 115, Fig. 4) during which the bar code stored in
shift register 356 may be effectively transferred to com-
parator 336, before it is cleared responsive to the signal
from memory 380.
If the film is travelling in a reverse direction,
the output from B sensor 104 is read in-to shift reyister 356
(with shifting in a right hand direction) each time that a
clock pulse from A sensor 106 appears at the output of AND
gate 376. This AND gate output may appear during the third
segment in the operation of the allotter 300.
` 1139865
If the film is travelling in a forward direction, a
signal feeds back over wire 362 to a shift left (SL) terminal.
This means that the bar code information read by the B sensor
is shifted in a leftward direction each time that a clock
pulse from A sensor 106 appears at the output of AND gate
376. Thus, it should be clear that the same in~ormation is
stored in shift register 356 responsive to the two bar codes
92, as shown at 346, 348 in Fig. 12.
It may be recalled that the information (T) de-
rived from the encoded output of the keyboard 312 was storedin comparator 336 during allotter time segment 1. The
information (S) derived from the bar code is stored in
comparator 336, as it is read by the sensors. The comparator
336 compares this stored information (T) and (S) and gives
an output 384 which indicates which (S or T) is greater or
when the two are equal. When the value of stored bar code
information (S) is less than the value of the stored key-
board information (T), the AND gate 338 conducts each time
that allotter 300 segment 2 is energized. Likewise, AND
gate 342 conducts when the bar code information (S) is
greater than the keyboard information (T). When the bar
code information (S) is equal to the keyboard information
(T), the AND gate 340 conducts. A terminal S ~ T is marked
whenever the terminal S = T is not marked. The marking at
terminal S ~ T energizes the "Go" wire, also seen in Fig. 8.
The forward motor 202 is driven responsive a signal
transmitted from AND gate 338, through contacts 386 and OR
gate 388 to the forward driver amplifier 206 and motor 202,
while the "Go" wire is marked via OR gate 387. Simultaneous-
ly, a signal is returned over wire 362 to indicate the for-
ward direction of film travel to the exclusive OR gate 364
and to the shift register 356 (i.e., shift register 356
~39865
shifts leftwardly responsive to s sensor signals at input
360 when wire 362 is marked).
The reverse motor 204 is driven responsive to a
signal transmitted from AND gate 342, through switch 390 and
OR gate 391, to the driver amplifier 208 and the reverse
motor 204, while the "Go" wire is marked via OR gate 387.
Note that on reverse drive, no signal is fed back via wire
362 so that the shift register 356 stores bar code infor-
mation by shifting rightwardly, responsive to B sensor
I0 signals at input 361.
- As the film travels, there comes a time when the
desired bar code passes under the A and B sensors. At that
time, the signal switches from S >T through S = T to S < T
or from S < T through S = T to S > T, as the case may be,
since inertia of the moving transport system carries the
film beyond the desired film area. At that same time, the
AND gates 338 and 342 switch their conductive states. The
formerly driven motor ceases to be driven, and the formerly
undriven motor is driven. The reversal of the driven motor
causes the film to move back in the reverse direction, as
graphically shown in Figs. 5 and 6.
Since the ~ilm has just reversed its direction of
travel, it will not have had enough time to get up to speed.
Therefore, the film is travelling relatively slowly when the
desired bar code is next encountered. The comparator signal
again passes from S < T or S > T (depending on the direction
of film travel) to S = T. ~hen the output is S = T, the
marking disappears from the terminal S ~ T. At that time
the speed control circuit 324 modulates the "Go" signal ap-
plied via wire 406.
113986S
The AND gate 340 conducts to apply a signal toinhibit the AND gate 304. The allotter 300 ceases stepping
back and forth between segments 2, 3. On the next pulses
from the free running oscillator, the allotter 300 steps
onto segments 3 and 4.
When the comparator 336 detects an approximate
equality (i.e., the film is within one bar code of the
desired photographic film area), an inhibit is removed from
terminal 398 of the AND gate 400. This prepares the circuits
to stop the film with a controlled deceleration curve.
After the inhibit is removed from the gate 400, the
potential on the fourth segment of allotter 300 is applied to
an astable multivibrator 404. Responsive thereto, the multi-
vibrator begins to pulse "Go" wire 406 in order to interrupt
the energization of the motors. Also, responsive to the
output of the gate 400, the ramp control circuit 408 begins
to gradually modulate the astable period of the multivibrator
404, as shown in Fig. 13. Initially the motor drive is
energized for short periods of time and de-energized for long
periods, as shown in the curve of Fig. 13A. As the ramp
control circuit 408 progressively increases its output, the
"On" durations from the multivibrator 404 become progressively
longer, as shown in Figs. 13B and C, and the motor receives
progressively higher levels of energization.
This gradual control of film transport speed,
responsive to a ramping of an energy interrupting duty cycle,
produces three results. First, it eliminates the need for a
tachometer. Second, it overcomes inconsistencies produced
by variations of unknown film transport friction, without
clutching. Third, there is a control over acceleration and
deceleration so that the rate of deceleration always exceeds
the rate of acceleration so that the film comes int~ final
position without requiring braking.
33
~' ~139~65
As explained in connection with Fig. 9, there comes
a time when the energy level which is progressively in-
creased, creates a torque that overcomes the static friction
of the film transport system. Thus, regardless of any
variations in instantaneous friction the motor always begins
to turn with the same characteristics, slowly at first, and
then with increasing speed.
Since the film is almost correctly positioned at
this time, there is not enough time for the transport
mechanism to acquire any appreciable speed or inertia. The
point is that the slowly increasing energy, caused by changes
in the duty cycle of multivibrator 404, just overcomes
~ static friction. Therefore, the film begins to creep along.
Although, the current is increasing, the film will be
stopped before it accelerates to any appreciable speed.
When the signal actually becomes and remains S = T,
the AND gate 340 conducts to energize AND gate 402. On the
fifth segment of allotter 300, AND gate 402 conducts and
operates the ~5UX switch 392. Contacts symbolically shown
at 386, 390 move to complete circuits through contacts 394,
396. The allotter 300 stands on the fifth segment until
the next operation of a key on the keyboard 312.
Final positioning means are provided for finding
an exact point in the bar code so that A sensor 106 is
exactly aligned over one edge of a specific one of the
selected bar code marks. More particularly, after the MUX
switch 392 operates, the A sensor 106 is connected through
terminals 394, contacts 386 and OR gate 388 to the forward
motor driver 206. The A sensor is also connected through
inverter 410 to terminal 396, contacts 390 and OR gate 391
to the reverse motor driver 208. This way, the forward
motor drives when the A sensor has an output and the reverse
34
1139~65
motor drives when the A sensor does not have an output. The
film repeatedly reverses direction, as often as may be de-
sired for the film to come to rest with a bar code mark
precisely positioned relative to the A sensor, as shown in
Figs. 5, 6. The exact nature of the final stopping position,
relative to the A sensor, depends upon bias potentials used.
Any of various means may be provided for deter-
mining when the film is finally positioned. As here shown,
the film reverses its direction a selected predetermined
number of times which brings the fllm to rest within
acceptable tolerance limits. Then, the film transport
reversals are automatically stopped. Each of the motors is
then energized at a reduced level in order to maintain film
tension.
In greater detail, before the film transport control
circuit (Fig. 11) goes into the find the mark sequence, the
S ~ T marking is applied over wire 413 to hold a reset con-
dition on the film stop circuit 324, thereby inhibiting its
operation. When S becomes equal to T, comparator 336
switches the marking from output terminal S ~ T to output
terminal S = T, which de-energizes wire 413 and thereby
removes the inhibit from the film stop circuit 324.
When the A sensor 106 detects a bar co~e mark,
flip-flop 414 generates a pulse which is transmitted through
OR gate 415 to drive counter 416 and reset the ramp control
circuit 408. When the A sensor moves off a bar code mark
inverter 410 conducts and the flip-flop 417 operates with
similar resul-ts. Each time that the ramp control circuit
408 resets responsive to a signal at terminal 420, the duty
cycle of multivibrator 404 repeats the increase of energy
I level depicted in Fig. 13 and again causes energy to be
applied at progressively higher levels to the driven motor.
1~;7
1~39865
The duty cycle of the multivibrator 404 goes through the
progression depicted by the curves 13A, B, C, in the order
in which these curves are drawn.
After a selected number of film drive reversals
have occurred, counter 416 reaches an output terminal 418.
At this time, both of the OR gates 388, 391 are energized
from output terminal 418 so that both of the motors 202, 204
are energized simultaneously, to maintain film tension.
At the same time, the signal transmitted from
counter output terminal 418, through capacitor 419, reverses
the ramp control circuit 408. This time the duty cycle of
the astable multivibrator 404 progresses from a high energy
level tFig. 13C) to a low energy level (Fig. 13A), inversely
to the order in which these curves are drawn. Thus, the
"Go" wire is modulated via conductor 406 and OR gate 387.
There is a reducing energy level duty cycle, which holds a
constant film tension without enabling the motors to actually
move the film.
The circuit remains in this condition until the
next operation of a key in keyboard 312, at which time the
allotter 300 steps off the fifth segment. On the zero
segment of allotter 300, all circuits are reset to normal.
Then, the circuit of Fig. 11 repeats the above-described
sequence, when the allotter 300 reaches segment "1".
Fig. 2 illustrates a "plus 1" operation in its
disclosure of a special bar code 89 which is a single wide
mark. The user pushes a special key in keyboard~312 when
he wishes to advance the roll of microfilm to display the
next photographic area. It is somewhat similar to turning
the page of a book. For this, the special key in keyboard
312 is equipped to transmit a special "plus 1" ~ode. An
AND gate 412 is wired to conduct whenever that special code
is sent.
36
` 113986S
In greater detail, the "plus 1" control circui-t is
shown and explained by Figs. 16-21. More particularly, Fig.
16 illustrates the possible differences between an exemplary
two bar codes and "plus 1" code. The bar codes always in-
clude a pluraltiy of long and short marks, as shown in Fig.
3; the "plus 1" mark includes only one long mark. Exemplary
bar code 16A begins with a short mark 500 followed by a long
mark 502 and any other combination of marks (not shown). sar
code 16B begins with a long mark 504, followed by a long
mark 506 and any other combination of marks (not shown). Of
course, the second marks 502, 506 may also be short marks;
however, this distinction is totally irrelevant. The "plus
1" mark is a single long mark, not followed by any other
combination of marks. Elence, the object of the "plus 1"
mark is to enable the film transport to advance, responsive
to a single wide mark, from photographic area to photographic
area, one at a time, as explained above in connection with
Fig. 2. If the advancing fiim does not contain a "plus 1"
mark, it returns to the last bar code. This is somewhat
similar to turning a page and finding the start of a new
chapter, in which case, the reader may wish to return to the-
start of the chapter that he is reading.
Figs. 17-19 are timing charts, similar to the chart
of Fig. 4, for explaining the A, B sensor outputs responsive
to the three codes of Figs. 16A-C. Thus, for example, the
bar code of Fig. 16A produces the outputs of Fig. 17. It
should be noted that the first output pulse 510 of the Bl
sensor curve occurs responsive to the bar code mark 500.
Pulse 510 then disappears before the parity check envelope
Dl goes "high" at 512 ~i.e., sensor A goes "low" while
senspr B iS "high"). Likewise, in Fig. 18 the first output
pulse 514 of the B2 sensor curve disappears before the
~139865
parity check envelope D2 goes "high" at 516 (again sensor A
goes "low" while sensor s is "high"). However, in the "plus
1" graph (Fig. 19), the parity check envelope D3 never goes
"high" because sensor B is "low" when sensor A goes low.
Accordingly, the truth table of Fig. 20 may be
drawn after an inspection of Figs. 17 19. Cell 1 is taken
from Fig. 17 and shows that if the parity envelope D goes
high (i.e., is 1) and if the "1" bar code pulse is "0",
cannot be a "pulse 1" code. Likewise, cell 2, which is
taken from Fig. 18, shows that there is no "plus 1" mark
when the parity envelope D goes high and the "1" output is 1.
There is a "plus 1" mark only when the signals are as shown
in cell 3, where the parity envelope D is O (i.e., does not
go "high") and there is a "1", or wide first pulse en-
countered by the B sensor. If the parity envelope does not
go high and the B sensor has a "1", it means that there is
one and only one mark in the bar code and that the one mark
is no shorter than 2x or longer than 3.5x, using the
nomenclature of Fig. 4. This combination virtually insures
that the system will not respond to a smudge on the film.
Fig. 21 shows a circuit for operating the film
transport responsive to an operation of a "plus 1". In
greater detail, the "plus 1" key causes an AND gate 412 to
conduct and drive a sequence counter 520 via OR gate 522.
The counter takes one step to initiate a first
sequence whereby forward motor 202 is started via wire 524
and OR gate 526. Simultaneously, one input of AND gate 528
is energized. If the A sensor 106 is standing over a bar
code mark, inverter 530 does not conduct. However, once the
film moves far enough, the bar code mark clears the A
sensor and inverter 530 switches on. The AND gate 528 con-
ducts to step counter 520 via OR gate 522.
" 1139~365
The counter 520 stands on its second step and the
second sequence begins. Motor 202 continues to run res-
ponsive to the signal transmitted over wire 532 and -through
OR gate 526. The upper input of AND gate 534 is energized.
After the film reaches the end of a photographic area, the
next bar code moves under the A sensor 106. The lower input
of the AND gate 534 is energized to step counter 520 via OR
gate 522; the se~uence counter step on to motivate the third
sequence.
In the third sequence, the circuit looks for a
detection of the "plus 1" bar code by the B sensor 104. The
potential on wire 535 keeps the forward motor running and
energizes the upper input of AND gate 536. Responsive to
the B sensor reading a mark, AND gate 536 conducts to step
the sequence counter 520 via OR gate 522.
It is now necessary to read the bar code to deter-
mine whether it is a single wide mark or a series of bar code
marks. Accordingly, on the fourth step of counter 520, the
motor 202 continues to run responsive to the marking on wire
538, and the upper input of AND gate 540 is marked. When
the bar code mark moves away from the A sensor 106, inverter
530 energizes the lower input of AND gate 540 to step the
sequence counter 520 to the fifth step.
However, if the B sensor 104 does not detect any bar
code mark Oll the fourth step of counter 520, there is a
problem and the "plus 1" sequence should be stopped
Accordingly, an inverter 544 conducts while no bar code mark
is under the B sensor in order to mark the upper input of
AND gate 552. When AND gate 534 conducts to step the counter
520 to the third step, the AND gate 552 conducts to start a
timer 554. For a measured period of time the timer 554
holds an inhibit on gate 556. By the time that timer 554
times outl the B sensor 104 should have found a bar code
mark, in which case, AND gate 536 conducts to continue
holding an inhibit on the AND gate 556. The gate 556 is no
longer capable of having an output after the sequence switch
520 step off its step 3. However, if the B sensor 104 has
not found a bar code mark, the inhibit is not present at the
upper input of gate 556 when the timer 554 times out. There-
fore, gate 556 conducts to stop the "plus 1" sequence.
The fifth sequence occurs when both the A and B
sensors 106, 105 are reading a mark (as shown in Fig. 19).
Responsive thereto, inverters 530, 544 conduct, and acting
through AND gate 546, energize the upper input of AND gate
548. The lower input of gate 548 is energized when the
counter 520 is setting on its fifth step. Responsive to the
output of AND gate 548, the MUX switch 392 (Fig. 11) operates
and the transport goes into its find the mark sequence. When
the mark is found, wire 550 is marked and sequence counter
520 steps to its sixth step, from which the circuit resets to
normal.
The parity envelope cannot appear during a valid
"plus 1" sequence, as will be apparent from Figs. 16-20. If
a parity envelope does appear, memory 380 produces a signal
at its Q terminal. Responsive thereto, gate 548 is inhibited
so that the MUX switch cannot operate, sequence counter 520
is reset to cancel the "plus 1" operation, and flip-flop 562
is set. The flip-flop 562 energizes the upper input of AND
gate 564, where there is a coincidence with the output of
the "plus 1" AND gate 412. Driver 208 and reverse motor 204
operates. The film is now driven backward through any
number of "plus 1" area codes, each of which is marked by a
single wide mark.
"` 113~86S
The output of AND gate 564 is applied through an
OR gate 566 to step a counter 568 to its first or "1" step,
where it marks the lower input of AND gate 567. Counter
568 remains on step "1" while the film rewinds. Evenutally,
the film comes to a full and complete bar code, which
causes a parity envelope to reappear. The memory 380
conducts to mark the upper input of AND gate 567 and thereby
feed back a signal through OR gate 566 to step counter 568
on to the Step "2". There, a signal is produced to reset
flip-flop 562, de-energize AND gate 564, and terminate the
"plus 1" circuit control over rewind. Also, the output of
counter step 2 causes the circuit of Fig. 11 to go into a
"find the mark" sequence to position the film on the full
and complete bar code that was just found. While the trans-
port is going through its find the mark routine, step 2 of
the counter 568 holds an inhibit on gate 570 to prevent the
OR gate from responding to a mark found signal. When the
mark is found, the counter 568 is reset to de-energize the
"2" output. This removes the inhibit from gate 570.
20 Thereafter, the OR gate 522 is energized by the "mark found"
wire 550.
Upon reflection, it is seen that the inventive
"plus 1" is quite different from prior art circuits. For
example, if the film in a prior art circuit is standing on
frame "514", a "plus 1" would advance the film to "515",
regardless of the information content of frame "515". In
the inventive circuit, a film standing on 514 (in this
example) is advanced to frame 514-1, then 514-2, 514-3...
etc. When the film reaches frame 515, it automatically
30 rewinds through all of the dash number frames (here -3, -2,
-1) and stops on the original frame ~14. When the images are
originally recorded on the film, they are numbered according
to the informational content of the recorded ima~es.
41
`` ~13~8~S
Sometimes, it is either necessary or desirable for
the machine to detect the direction of film travel, in-
dependently of the outputs 384 of the comparator 336 (Fig.
11). For this, three sensors (A, B, C) are used, as shown
in Figs. 14, 15. These three sensors are geometrically
arranged, as shown in Fig. 15 so that the C or third sensor
420 lies between the A and B sensors 106, 104. A11 three
sensors are positioned to read the same bar code.
It may be recalled that the narrow bar code mark
has a width of "X", the wide bar code mark has a width of
"2X", and the space between the A and B sensors is 1.5 "X".
Therefore, when each mark in the bar code is first read,
there are the four possibilities shown in Fig. 15 by the
truth table 424. More particularly, in either direction of
film travel, a wide bar code mark simultaneously covers all
three sensors to produce a binary word 111. ~lowever, a
narrow bar code simultaneously covers only two of the sensors
at a given time. Hence, if the narrow mark 422 passes under
the sensors in the reverse direction, there will be a
simultaneous output from the A and C sensors before there
is-a "0" output from the A sensor, to give the binary word
110 (as at 426). When the narrow mark travels in an
opposite direction the binary word is reversed to become
011 (as at 42~), before there is a "0" output from the B
sensor.
From Fig. 11, it will be recalled that wire 362 is
marked when the film is travelling in the forward direction.
An absence of a mark on this wire indicates that film is
travelling in a reverse direction. Thus, it is only
necessary for the three sensors (Fig. 14) to detect and
signal the forward motion and to feed the resulting signal
to gate 372 and to the SL input to the shift register 356.
42
139865
To connect the three sensor circuits of Fig. 14 to
the control circuit of Fig. 11, it is only necessary to
interconnect wires J, K and M in these two figures. Diodes
430, 432 prevent feed back between the circuit of Fig. 14
and the junction between the OR gate 388 and the MUX switch
386.
Each of the A, B, C sensors (Fig. 14) is connected
to its individually associated drivers 194, 196, 436 which
are, in turn, connected to individual stages in a three
stage register 440. (Sensors 104, 106 and drivers 194, 196
are shown in dotted lines in Fig. 14 since they already
appear in Fig. 11). The individual stages in register 440
are set each time that the output of the associated sensor
detects a mark in the bar code. By inspection of Fig. 15,
it will be seen that a forward film motion is always in-
dicated by the binary word "011", as shown at 428. Regard-
less of whether the narrow or the wide bar code mark passes
under the sensor, such mark changes to the binary word "011"
when the mark passes out from under the A sensor and is still
under the B and C sensors. On the other hand, if either the
wide or the narrow mark is under the sensors, the output
becomes "110" when the mark passes out from under the B
sensor.
The AND gate 442 conduc-ts only when the three
stages of memory 440 conduct simultaneously. This means
that a bar code mark has passed under all three sensors.
The gate 444 conducts when there is an output from the AND
gate 442, but not from the sensor A (i.e., sensor A must
turn off to remove an inhibit from input 446). A free
running multivibrator 448 repeatedly resets the memory 440.
i3986S
The speed of this electronic reset and the mechanical
transport speed are such that the output of the AND gate
442 does not have time to disappear before the output of the
A sensor 104 disappears. Accordingly, gate 444 conducts
only when the binary word "011" appears. If the film runs
in reverse direction, the B sensor 106 ceases to conduct at
a time when the A sensor 104 still has an output that
inhibits the gate 444. Before the bar code mark passes out
from under sensor A, the output of the free running multi-
vibrator 448 resets the memory 440. Hence, ~ate 444 never
conducts while the film is travelling in a reverse
direction. Thus, an output on the wire M indicates a for-
ward film motion and is effective in Fig. 11 in the same
manner that a marking on wire 362 is effective.
Those who are skilled in the art will readily
perceive how the disclosed structure may be modified.
Therefore, the appended claims are to be construed to cover
all equivalents falling within the true scope and spirit of
the invention.
44
