U.S. patent number RE29,104 [Application Number 05/522,686] was granted by the patent office on 1977-01-04 for method of scanning documents to read characters thereon without interference from visible marks on the document which are not to be read by the scanner.
This patent grant is currently assigned to Cognitronics Corporation. Invention is credited to David H. Shepard.
United States Patent |
RE29,104 |
Shepard |
January 4, 1977 |
Method of scanning documents to read characters thereon without
interference from visible marks on the document which are not to be
read by the scanner
Abstract
An optical character recognition system including a laser
scanner unit adapted to scan a document having preprinted markings
to indicate where the characters are to be placed. Variations in
light intensity reflected from the document and characters produce
scan signals which are processed to determine the characters. The
color of the markings on the document is related to the laser
frequency such that the light reflected from the markings has the
same intensity as the light reflected from the document background,
so that the presence of the markings does not interfere with the
reading of the characters.
Inventors: |
Shepard; David H. (Rye,
NY) |
Assignee: |
Cognitronics Corporation
(Stamford, CT)
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Family
ID: |
26868607 |
Appl.
No.: |
05/522,686 |
Filed: |
November 11, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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876694 |
Nov 14, 1969 |
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701670 |
Jan 30, 1968 |
3582884 |
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523367 |
Jan 27, 1966 |
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Reissue of: |
172924 |
Aug 18, 1971 |
03820067 |
Jun 25, 1974 |
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Current U.S.
Class: |
382/163; 250/226;
382/175; 382/322 |
Current CPC
Class: |
G06K
7/10 (20130101); G06K 7/14 (20130101); G06K
9/2018 (20130101) |
Current International
Class: |
G06K
7/10 (20060101); G06K 7/14 (20060101); G06K
9/20 (20060101); G06K 007/14 () |
Field of
Search: |
;340/146.3F,146.3B
;178/7.6 ;250/226,567,568 ;350/6,7 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Boudreau; Leo H.
Attorney, Agent or Firm: Parmelee, Johnson &
Bollinger
Parent Case Text
This application is a continuation of my application Ser. No.
876,694, filed Nov. 14, 1969 (now abandoned), which in turn was a
continuation-in-part of my copending application Ser. No. 701,670,
filed on Jan. 30, 1968, now U.S. Pat. No. 3,582,884.Iadd., which in
turn was a continuation-in-part of my copending application Ser.
No. 523,367, filed on Jan. 27, 1966 (now abandoned).Iaddend..
Claims
I claim:
1. The method of machine reading of characters placed on a document
form having pre-printed thereon markings visible to the eye but
which are not to be read by the character reading machine, said
method comprising the steps of:
producing by means of a laser small-diameter beam of monochromatic
light, the width of said beam being small relative to the size of
said characters;
presenting to said beam of monochromatic light a document form
having said characters in place on a reflective background and
carrying said pre-printed markings in a color related to said
monochromatic light such that said beam produces from said markings
a reflected light intensity equal to the intensity of reflected
light said beam produces from said background, whereby said
markings and said background are not distinguishable with respect
to the light reflected from said document form in response to
impingement of said monochromatic light beam;
scanning said document by sweeping said narrow beam .[.at.]. along
a series of consecutive, adjacent paths intersecting said character
and said markings;
developing signals representing the amount of light reflected from
said document at evenly-spaced points along the scan path
throughout the regions of said document containing said characters;
and
analyzing said developed signals to determine the nature of the
characters on said document. .Iadd.
2. The method of machine reading of characters placed on a document
having presented thereon markings visible to the eye but which are
not to be read by the character reading machine, said method
comprising the steps of:
producing by means of a laser a small-diameter beam of
monochromatic light, the width of said beam being small relative to
the size of said characters;
presenting to said beam of monochromatic light a document having
said characters in place on a reflective background and carrying
said markings in a color related to said monochromatic light such
that said beam produces from said markings a reflected light
intensity equal to the intensity of reflected light said beam
produces from said background, whereby said markings and said
background are not distinguishable with respect to the light
reflected from said document in response to impingement of said
monochromatic light beam;
scanning said document by sweeping said narrow beam along a series
of consecutive, adjacent paths intersecting said character and said
markings;
developing signals representing the amount of light reflected from
said document at evenly-spaced points along the scan path
throughout the regions of said document containing said characters;
and
analyzing said developed signals to determine the nature of the
characters on said document. .Iaddend.
Description
This invention relates to character reading apparatus and methods.
More particularly, this invention relates to apparatus adapted to
optically scan documents bearing characters to be read, and to
produce output signals identifying such characters. The output
signals typically are used as input information for a high-speed
digital computer. .Iadd.
The present invention is particularly directed to optical character
recognition apparatus including a laser scanner unit adapted to
scan a document carrying informational markings in addition to the
characters to be read. Variations in light intensity reflected from
the document and characters produce scan signals which are
processed to determine the characters. The color of the markings on
the document is related to the laser frequency such that the light
reflected from the markings has the same intensity as the light
reflected from the document background, so that the presence of the
markings does not interfere with the reading of the characters.
.Iaddend.
.[.Optical character recognition apparatus of various types has of
course been available and used for many years. Predominantly, such
apparatus has been quite complex and expensive, and thus has been
economically suitable only in special applications such as where
the volume of reading required is relatively large. Various
proposals therefore have been made from time to time for reducing
the net operating cost in low-volume applications.
A significant step towards reducing operating costs is disclosed in
pending application Ser. No. 701,670, filed by the present inventor
on Jan. 30, 1968. That application shows a system including a
central processor which is time-shared among a number of customers
each having one or more remote scanner units adapted to receive a
character-bearing document and to send the central processor
electrical signals representing character information on the
document. The central processor sorts out the received signals and
performs a character recognition function to identify the
individual characters on the scanned documents.
In a typical character recognition application, the documents to be
scanned will not all be of the same type and thus ordinarily will
require different processing procedures. This is of course the
general case in a multi-customer time-shared system, because each
customer will have an individual information format suited to his
own needs. To avoid requiring batch-processing of separate
categories of documents, that is, to permit intermixing of
different types of documents, the processing procedures should
automatically be matched to the particular document being scanned.
This result has been uniquely achieved through basic concepts of
the present invention.
In accordance with one specific aspect of this invention, certain
functions of the scanner unit of an optical character recognition
system are automatically controlled, in response to information
derived from characters on the document being scanned, so as to
carry out the scanning function with optimized effectiveness. In
accordance with another specific aspect of the invention, control
information derived from the scanned document determines the
disposition to be made of the data represented by the information
characters presented on that document..].
In a preferred embodiment of the present invention, to be described
hereinbelow in detail, the documents scanned consist of printed
forms each presenting in its upper left-hand corner predetermined
control character indicia related to the type and location of
information characters to be inserted in specific subsequent places
on the form. In one arrangement, the control indicia consists of a
nineteen digit number, termed an Identification Number (or ID
Number).
The first eight digits of the ID Number are referred to as the
"Service Number," and identifying certain detailed instructions
concerning the processing of the document. For example, one digit
may represent the vertical distance on the document between the
control character group and the first text line of information
characters, so that upon detection and decoding of that one digit,
the processor can cause the scanner to skip quickly over the
intervening space and initiate scanning of the information
characters without undue delay. The next ten digits of the ID
Number are referred to as the "Customer Number," and identify the
source of the document, as well as indicating, for example what
disposition should be made of the scanned information. The last
digit of the ID Number is a so-called check digit, used in known
fashion to insure that the preceding digits of the control
characters have been read accurately.
The document form is provided with additional control character
indicia at various locations below the ID Number. These additional
control characters, referred to herein as Field Codes, identify
detailed instructions respecting the material appearing in
particular data fields.
All of the digits of the control character indicia are scanned
optically to produce, as described in the above-identified
.[.pending application Ser. No. 701,670.]. .Iadd.U.S. Pat.
3,582,884.Iaddend., corresponding data signals which are
transmitted to a central processor station where they are directed
to conventional character recognition equipment (or analyzed
through a sub-routine of the processor). The processor
automatically identifies the first group of characters scanned from
any document as the ID Number, and checks the group of characters
to be sure that they are valid. The processor then analyzes
selected characters of the group to determine the specific digits
presented (i.e., 0, 1, 2 etc.), and produces corresponding function
signals to further the processing of the document currently being
scanned. The same general procedures are used in identifying the
Field Codes and producing corresponding function signals as will be
described.
There are a variety of different functions which can appropriately
be carried out in this respect. For example, in the disclosed
embodiment means are provided for (1) controlling the movement of
the document through the scanning unit, (2) determining the
horizontal segment of the document to be scanned, and (3) adjusting
the threshold level of the electronic detector circuitry in the
scanning unit. Still other functions relate to the processing of
data by the computer, and the disposition of the recognized
information characters, such as directing the information to
storage, or to specified locations.
Accordingly, it is an object of this invention to provide improved
apparatus, methods and techniques for processing documents by
optical character recognition means. A more specific object of the
invention is to facilitate the intermixing of different types of
forms particularly in a remote optical character recognition
system.
Other objects, aspects and advantages of the invention will in part
be pointed out in, and in part apparent from, the following
description considered together with the accompanying drawings, in
which:
FIG. 1 is a schematic diagram showing the basic components of a
system embodying and utilizing the present invention;
FIG. 2 shows an information form with preprinted control indicia;
and
FIGS. 3A-3C shows details of the control system responsive to the
control indicia.
GENERAL DESCRIPTION OF THE SYSTEM
Referring now to FIG. 1, the system comprises a number of remote
scanners 10 preferably of the type disclosed in copending
application Ser. No. 624,445, filed Mar. 20, 1967, by E. J. Gushue
and D. H. Shepard, now abandoned. Such a scanner is operated by
inserting the document to be read into an infeed chute 12 with the
lines of written characters extending from side-to-side, i.e.,
perpendicular to the direction of document movement. Conveying
means within the scanner housing automatically grips and advances
the document in a high-speed step-wise indexing movement around a
drum 14 to an outfeed chute 15. While in the scanner, the document
is examined by a small-diameter laser light beam which is swept
from side-to-side across the document by a rotating multi-mirror
16. This small diameter laser light beam produces a scanning spot
which is small relative to the size of the character, as disclosed
in the above-identified application Ser. No. 876,694, and may have
a diameter of 0.005 inch to .[.0.001.]. .Iadd.0.01 .Iaddend.inch,
as disclosed in said application Ser. No. 624,445.
Between each indexing step of the drum, the light beam makes one
pass horizontally across the document, parallel to the text lines
of written characters on the document. The amount of indexing
movement and the spot size on the document are substantially equal
so that the spot traces out a series of contiguous horizontal paths
through the lines of characters. This series of successive scans
effectively covers all parts of the characters to be read.
The scanning of the document produces electrical signals indicating
the presence or absence of character elements at evenly-spaced
points along the scan path. These signals are used to generate code
signals representing the basic scan data. The code signals are sent
over a transmission line 22 to a central station 24 where the codes
are accumulated in a corresponding line buffer 26.
The interconnecting circuitry between the scanner 10 and the
central station 24 also includes a separate return transmission
line 28 for communicating in the reverse direction. The return line
28 is used for sending to the scanner various operational commands,
such as a "Read" command comprising a train of clock pulses to
cause the unit to perform the scanning function. Other specific
commands will be discussed hereinbelow.
The line buffers 26 comprise control circuitry 32 which directs the
received code signals to a corresponding section of a rotating
magnetic drum 34 for temporary storage while data for a complete
line of characters is being accumulated. The control circuitry 32
also includes logic elements of known type to analyze each received
code and (a) determine the presence of a special start-of-scan
(SOS) code signal, (b) detect a certain code bit indicating that
the code contains character data, and (c) reset to start condition
if two start-of-scan signals are received with no intervening
character data codes.
When logic elements of the control circuitry 32 detect a complete
text line of characters, means are activated to send an "interrupt"
signal to a conventional high-speed stored-program computer 50
connected to the line buffers 26 (as well as other peripheral
devices) by the usual data-buss interconnection system generally
indicated at 52. The interrupt signal from a line buffer is sent
over line 54 and signifies to the computer that one of the
peripheral devices is requesting action. The computer thereupon
sends out on the "device selection" line 56 a "roll call"
identifying each of the devices in sequence by special codes. The
line buffer (or other device) requiring service responds to the
computer on a separate so-called "skip line" (not shown) when its
code is called.
The computer 50 follows a pre-set stored program of steps to
determine what action is required, and then carries out such
action. In the instance where a line buffer 26 signals that it has
a complete text line of characters, the computer will order the
character data transferred to a so-called "decoder scan converter"
60 which serves all of the line buffers on a time-shared basis. The
computer also sends control signals causing the line buffer to read
out its stored data to the line buffer data channel while the
decoder scan converter receives and places that data in storage,
typically a core memory. In one practical embodiment, such read-out
from the line buffer drum required only between about 6 to 48
milliseconds, the exact time duration depending upon the amount of
coded data needed to specify the complete text line of
characters.
The decoder scan converter 60 serves primarily to translate the
coded data received from the scanner 10 into the basic
"black-white" format. That is, the decoder functions in effect to
reverse the coding procedure which was carried out at the remote
scanner. For this purpose, the converter 60 preferably comprises a
multi-plane magnetic core storage unit having a storage bit
corresponding to each "spot" examined (for black or white response)
by the scanner in covering a complete line of text. For example,
the core storage may provide space for the data from 48 sequential
scans each having 1024 black-white bits. These bits of data are
placed in the core storage in a manner effectively to reconstruct
the raw data initially detected by the scanner 10, i.e., as it was
before encoding for transmission to the central station.
When the decoder scan converter 60 has decoded and stored all of
the data representing a complete line of text from one line buffer
26, it interrupts the computer 50 and sends a signal indicating
that the decoded data is ready to be analyzed for recognition of
the individual characters. Such analysis can be performed by a
character recognition circuit generally illustrated at 70. The
analysis may alternatively be carried out by the computer, acting
under the control of a stored program such as disclosed in
copending application Ser. No. 758,219, filed by the present
applicant on Sept. 9, 1968, now abandoned.
The decoded data is read-out to the recognition circuit 70 in a
stream of data bits like that which would have been produced by a
conventional optical scanner making a series of consecutive
vertical sweeps through each character in sequence. This stream of
data is analyzed in a logical pattern to produce output signals
identifying each character in sequence. These character signals are
stored in a register 90 in the computer 60 corresponding to the
originating remote scanner 10, for further processing as will be
described.
THE PREPROGRAMMED FORM
FIG. 2 illustrates a typical business form 100 in accordance with
the present invention. This form is basically a conventional time
sheet such as are used by corporations for recording the time spent
by their employees on various jobs during a weekly period. In the
left-hand column are spaces for the employee to fill in the job
numbers. Subsequent columns for each day of the week provide a
three-unit space for filling in the number of hours (to tenths)
worked on a particular job on each day. The form includes spaces
for totalizing these figures both horizontally and vertically.
In the upper left-hand corner of the form 100 is a so-called
Identification Number (ID Number) generally indicated at 102. This
form with its ID Number is associated with a specific customer of a
remote optical character recognition system such as shown in FIG.
1. The customer will have on his premises one or more of the remote
scanner units 10, which will transmit to the central processor scan
data from the forms 100 (and other forms were appropriate). The
central processor first identifies the ID Number from the
distinctive characteristic of its location on the form. The central
processor receives from individual digits of that number certain
basic starting instructions directing various parts of the system
to carry out particular operations specifically devised for
handling the document form then in the scanner.
Preferably, all indicia pre-printed on the document form 100, with
the exception of the control code characters, is of a color to
which the scanner 10 does not respond. For example, with a
particular type of red-light laser found useful in such scanning
operations, the noncontrol indicia on the form is also of a red
color. By proper selection of the red ink color, the reflected
light intensity will be equal to that from the white background,
i.e., the detector will be "blind" to the red printing. Thus, the
scanner will respond only to the control characters and the
information characters placed in the assigned spaces on the
form.
The first eight digits of the ID Number 100 are the so-called
Service Number. This number identifies the class of form, and
contains the basic initial instructions as to where the information
is located on the form, the type of characters on the form, and
what is to be done respecting the information.
The first digit of the Service Number identifies the specific type
of program to be carried out. In the case of all preprogrammed
forms carrying various supplementary control code groups (so-called
Field Codes as will be described herein), this number is always a
"1."
The second digit of the Service Number defines the initial vertical
"skip distance," i.e., the vertical distance on the form 100
between the ID Number and the first text line containing characters
to be scanned for recognition purposes. The central processor
includes means responsive to this code digit for controlling the
movement of the document through the remote scanner, so as to skip
from the control characters of the ID Number directly to the
position where the next set of characters to be scanned is located.
Various skip distances can of course be assigned to specific
numbers of the second digit. In one arrangement, the numbers
represented skip distances of one-third inch increments, i.e., the
number "1" meant "skip one-third inch," the number "2" meant skip
"two-thirds of an inch," etc.
The third digit of the Service Number defines the initial
horizontal scan zone, that is, the horizontal segment where the
characters to be scanned will be located. Various arrangements for
relating the numbers 0-9 to specific scan zones can of course be
devised. One possible arrangement is as follows:
______________________________________ DIGIT VALUE SCAN SEGMENT
______________________________________ 0 100% 1 0-30% 2 0-40% 3
0-50% 4 50-100% 5 0-65% 6 0-75% 7 0-80% 8 0-90% 9 Special
(unassigned) ______________________________________
The fourth digit of the Service Number defines the class of
characters to be scanned, i.e., it specifies whether the character
set includes only numerics, or alphanumerics, and what type font is
expected.
The fifth digit of the ID Number defines the output format. For
example, the number "0" may indicate a variable length record, with
character sequence the same as in the input document, whereas the
number "1" may indicate a fixed length record, e.g., 80 characters
long.
Digits 6-8 of the Service Number are available for various control
functions, such as designating the disposition of the processed
data. For example, a "0" for the sixth digit may indicate that the
recognized characters should be transferred to storage at the
central station, for subsequent delivery to the customer, whereas
the number "1" may indicate that the recognized character data is
to be sent immediately to the customer by remote transmission for
storage on magnetic or paper tape.
The Customer Number, represented by digits 9-18, serves primarily
to identify the customer so as to facilitate various processing
routines, including billing and the like. For example, digits 9-11
may be the customer's telephone area code, and digits 12-16 may be
the first five digits of the customer's telephone number. Digits 17
and 18 may be used to identify the particular job or application
represented by the document.
The nineteenth digit preferably is a check digit, for example a
digit developed in accordance with Luhn's scheme, applicable to all
18 preceding digits. The computer 50 examines the entire ID Number,
including the check digit, to determine whether the number is a
"checking number," i.e., whether the sum of the check digit and all
of the other digits (including certain substitutes according to a
predetermined pattern) is a multiple of 10.
FIELD CODES
The document form 100 includes a second type of control code 106 at
various locations in the data fields below the ID Number 102. These
control codes, termed "Field Codes," are not identifiable as such
by their location on the document, as is the ID Number. Instead,
they are provided with a distinctive stylistic characteristic
embodied in the character format, specifically (in the preferred
embodiment) a special corner bracket 110 adjacent the upper
left-hand corner of the first digit of each such control code
group. Such control codes preferably are a consecutive series of
numbers. Typically, information data to be filled in on the form
will follow a control code group after an intervening space.
Each of these Field Codes ordinarily is associated with a specific
data field of the document. The Field Codes identify detailed
instructions concerning the associated field, such as by giving a
single order to be obeyed, or a definition of exactly what is to
follow.
In the embodiment disclosed herein, the first digit of each Field
Code indicates its field type, whereas the second, and succeeding
digits (if any), indicates an argument in the mathematical sense,
i.e., a number of characters, a distance, or the number permitted
in the field. Various specific meanings can be assigned to the
control code digits, and the following describes one practical
example of the kind of coding which can be utilized:
The control digit 1 indicates that information following the
control code group (until another countermanding control code is
encountered) is a single fixed-length field, as defined by the
second code number (following the 1), and in all parts of which
data must be present.
The control digit 2 has the same significance as 1 except that the
field must also be a checking number.
The control digit 3 indicates that the following field is of
variable length, but not to exceed the length indicated by the
second digit of the control code.
The control digit 4 has the same significance as 3 except that the
code contains a third digit which indicates a minimum length
allowed.
The control digit 5 indicates that the following field is
associated with an accumulator, as defined by the succeeding digits
which must be on the same line.
Code Format: 5XYZ
X = accumulator function
Y = maximum length of the field
Z = minimum field length
Value of X:
1 = add field contents to accumulator, and check Z
2 = subtract field contents from accumulator, and check Z
3 = compare field contents to the accumulator, and check Z
4, 5, 6 = same as 1, 2, 3 respectively, except that Z is not
specified.
The control digit 6 specifies a change in the horizontal scan
pattern; the control code digits following 6 are used to define the
new scan zone desired.
The control digit 9 indicates that the following control digits of
the group represents a code of a special category; for example, 90
indicates that the line contains only control codes, until the code
0 is encountered, and is a format to be followed in all succeeding
lines (until countermanded by a new control code); each such code
applies to the field below starting in identical horizontal
positions.
The control code 91X commands that the scanner 10 skip the distance
represented by X after completing the line of text in which the
control code was encountered. Various digits may of course be
assigned specific skip distances, and one number such as "0" may
direct the scanner to "skip out" the document, i.e., advance it at
maximum speed through the scanner and out the exit slot.
The control digit 0 indicates that the following digit of the code
is the check digit for all control codes on that line. A specific
control digit, such as 0, can be used at the start of a line to
serve as a bench mark or reference point for skew compensation, to
assure that the beginning and ending point of the fields are
properly located.
Referring now to the specific Field Codes shown on the document
100, the code 24 indicates that the corresponding field is fixed
length, and contains four digits including a check digit. The code
16 indicates a fixed length field of six digits, with no check
digit. The code 06 gives the number "6" as the check digit for all
of the control codes on the line. Such an identified check digit
may if desired also indicate the end of the data to be scanned from
that line.
The code 90 indicates that the line contains only control codes,
and that such codes apply to the fields in lines below the code
line. The immediately following code 26 thus identifies the
six-digit field (column) for inserting job number, and indicates
that each job number is arranged as a checking number to be
analyzed for that characteristic. Similarly, the code 31 indicates
a field having no more than one digit, for the column representing
the type of activity performed by the employee. Each of the codes
543 identifies respective three-digit fields the data from which is
to be added to the accumulator of the computer. The code 5630
identifies a three-digit field the data from which is to be
compared to the amount in the accumulator to check for equality; if
not equal, the computer will issue a reject signal. The code 951,
910 03 is an end-of-page designator, commanding that the document
be skipped out of the scanner.
SYSTEM DETAILS
It already will be apparent from the above description how the
system operates automatically, with the aid of the pre-programmed
form 100, to carry out specific tasks pertinent to the particular
form and the data filled in on that form, without the need for such
specific programming instructions to be developed for each
individual application and inserted ahead of time in the computer
50. That is, the computer will be programmed in general to examine
the control code indicia on each form scanned, and the particular
indicia printed on the form will in effect complete the program
instructions for the required processing of the document. Thus the
forms can be intermixed in a scanner without loss of operating
efficiency, and a number of customers can be handled by one
time-shared computer without requiring specific instructions in the
computer program related to particular customers.
The central station 24 contains the electronic facilities to
accomplish the tasks already explained, including the tasks of
distinguishing the control character indicia from the information
characters, decoding the control characters, developing in response
to such decoding suitable function or "action" signals for
effecting a particular result (such as operating the drum stepping
motor of the scanner), and directing signals to appropriate
apparatus for executing the desired command. Suitable electronic
facilities for accomplishing such tasks can take many forms, and
the detailed nature of such facilities will be apparent to those
skilled in the art. In general, most of the tasks can with
advantage be performed by a high-speed time-shaped computer
operating under stored-program control, and skilled programmers can
within the known boundaries of their art devise suitable
instructions for the computer.
FIG. 3 has been included to present details of one system
embodiment for carrying out the particular functions discussed
above. In this diagram, certain of the functions which typically
would be carried out by computer manipulations have been
represented by conventional block diagrams, to clarify the nature
of the operations, and also to indicate that in some instances
hardware could be used for such purposes, even though in general
computer manipulations will be the comprising efficient mode of
handling the problem.
Referring now to the left-hand portion of FIG. 3, there is shown
schematically a light-sensor 200 which detects the light reflected
from the document 100 as the laser beam sweeps thereacross. This
sensor produces a corresponding output voltage which is fed to a
pre-amplifier 202, having a conventional normalizing feedback
circuit 204. The amplified output is directed to a known threshold
circuit 206 which in association with an amplifier 208 produces a
binary output indicating whether the reflected light intensity is
above or below a selected threshold level. The output of amplifier
208 is directed to a flip-flop 210, clocked by scan clock pulses
derived in known fashion, and operable to produce on the output of
the flip-flop a series of binary (black-white) pulses indicating
the presence or absence of character elements at uniformly spaced
points along the scan path.
The clocked pulses from flip-flop 210 are fed to an AND gate 211,
controlled in a manner to be explained, and which when opened
directs the black-white pulses to coding apparatus generally
indicating at 212. Such coding apparatus is disclosed in the
above-mentioned parent application Ser. No. 701,670, and produces a
series of code groups indicating the scan lengths between
particular events occurring during a scan, such as successive
white-to-black transitions. The code groups are stored in a buffer
214 for subsequent transmission over the outgoing line 22 leading
to the central station 24.
The coded data is received at the central station 24 and directed
to a line buffer 26. The line buffer temporarily stores the data in
a circulating shift register 220 from which the data ultimately is
transferred to a maganetic drum 222, in accordance with the
operation of associated logic circuits. When a complete text line
has been so stored, the interrupt circuit 224 is activated to the
computer 50, and the data on the drum is read out to the decoder
scan converter 60, and from there to the recognition circuit 70,
all as previously disclosed.
The recognition circuit 70 performs in known fashion to determine
the identity of each of the characters of the line of text. Signals
identifying these characters are placed in a storage register 90
for subsequent processing. One such storage register may be
assigned to each scanner 10.
The computer 50 checks to determine whether the characters stored
in the register 90 represent an ID Number 102. If they do, the
computer processes the character signals in a predetermined manner
to develop the information and instructions applicable to the
particular form being scanned.
As noted hereinabove, the ID Number 102 possesses the
distinguishing characteristic of a special location on the document
100; that is, the ID control character indicia are located in the
upper left-hand portion of the document. Thus, to determine that
the character signals in the register 90 represent an ID Number,
the computer program includes a routine to check whether the
signals are the first to be derived from the document being
scanned. To do this, the computer needs only to be sent a signal
when the document is first inserted into the scanner, and the
computer program can be arranged in any conventional manner to
determine whether the stored text line is the first received after
that signal was received.
The scanner 10 can of course be provided with any of various means
for detecting the insertion of a document and sending a distinctive
signal thereof to the computer 50. Rather than using a mechanical
detector, the scanner preferably may be provided with a "document
present" circuit 232 coupled to the feedback circuit 204 of
amplifier 202. When no document is present, no light is reflected
to the sensor 200, and thus no feedback signal generated. When a
document is inserted, the reflection of light produces a feedback
signal which is detected by the document-present circuit 232. This
circuit directs a corresponding signal through a line 234 to cause
the coding apparatus 212 to produce a special document-present
signal to be sent to the central station 24 for transfer to the
computer 50 and utilization as described above in recognizing the
ID Number as the set of characters first scanned from the
document.
The computer 50 also is programmed to make logic checks on the ID
Number characters. This procedure is illustrated by the block 240
in FIG. 3. Specifically, the computer determines the number of
characters to be sure there are nineteen in all. The computer also
examines the ID Number to be sure it is a "checking number," i.e.,
that the sum of the check digit and all of the other digits
(including certain substitutes) is a multiple of 10. If these logic
checks do not prove out, the ID Number characters are sent by the
computer to the CRT display 86 (FIG. 1) for examination by the
operator.
All characters on the CRT display 86 are "marked" by an arrow or
the like, to indicate to the operator that there is an error
present in the number. If the operator can see that the information
presented is improper for an ID designation, she may actuate a
so-called "kill button" to send a signal back to the scanner
instructing it to eject the document and activate an alarm light to
gain the attention of the operating personnel at the remote
station.
If the ID Number checks out, the computer 50 thereupon carries out
a sequence of steps whereby specific characters of the number are
decoded and corresponding function signals are generated to carry
out the required action specified. Such decoding is a conventional
operation in computer data manipulations, and a variety of program
sequences can be devised in known fashion to produce the desired
results. Simply to illustrate this decoding function, however, FIG.
3 includes a block 242 presenting a number of conventional decoding
circuits 242a, 242b, etc., for analyzing respective characters of
the ID Number. Each decoding circuit produces an output signal
(i.e., a "high" level on one lead of the output circuit leads)
identifying the particular number decoded. Such signal is
transmitted to means for carrying out the specified function.
The output signals of the decoding circuits 242a and 242d for the
first and fourth digits of the ID Number serve to control certain
functions at the central station, and thus have been shown directed
through lines 244a and 244d to the computer program control
circuitry 246. Specifically, the first digit distinguishes the
program type, and thus the corresponding output signal directly
determines the further program sequences applicable to the document
being scanned. The fourth digit represents the type of character to
be read from the document, and thus the corresponding decode signal
is also directed to the program control 246 to select the
particular recognition program for that character type. If separate
hardware is used for the recognition sequences, rather than
program-controlled computer manipulations, the decoder output
signal will be directed to such hardware to place it in the proper
mode of operation for the particular character type indicated.
The second and third digits of the ID Number control corresponding
functions at the remote scanner 10. Such signals could be sent
directly back to the corresponding scanner, by various conventional
means. However, it is advantageous to utilize for such signaling
the basic communication system of the remote optical character
recognition system, simply because such utilization provides
important advantages of economy and simplicity. Thus the outputs of
decoding circuits 242b and 242c are shown connected to a
"function-signal generator" generally indicated at 250, and which
produces serially coded permutation output signals corresponding to
the numbers decoded from the ID digits.
Preferably, the function-signal generation will be effected by the
computer 50 through the means of a suitable program to produce in
known fashion such serially coded output signals. The block diagram
showing in FIG. 3 is in essence a schematic representation of the
coding operation, although of course the task can be accomplished
by conventional hardware. In any event, in one embodiment the
signal generator 250 serves to produce six-bit binary code groups
corresponding to the outputs from the decoding circuits 242b and
242c, with the sixth bit always a zero. The permutation code of the
other five bits identifies the specific command, i.e., whether skip
distance, or alteration of the horizontal scan zone.
The function signal generator 250 also is arranged to produce a
six-bit code specifying a change in the threshold level of the
electronic detector circuitry at the scanner 10, for use when
regular text lines are being read (not the ID Number). This
threshold circuit may for example have three possible levels, i.e.,
light, medium and dark, and ordinarily the scanner would be set on
the medium level at the start of reading. If the characters
inserted on the document are excessively heavy (or light), such
characteristic can be determined in known fashion by the
recognition circuitry, as explained in copending application Ser.
No. 758,219, filed on Sept. 9, 1968, by the present applicant.
Simultaneously, the computer can determine how many characters in
the line of text were not recognized, and if the number was above
some selected level, the computer will produce a signal on a line
251. This signal combines with a signal on line 251a from the
recognition circuit 70 indicating too heavy (or light) character
density, and together the signals cause the function-signal
generator 250 to produce a corresponding 6-bit code.
All the six-bit code groups developed by the function signal
generator 250 are directed to a transmitter 252 which normally
produces for the remote scanners a continuous stream of clock
pulses to serve as the "Read" command, as described in the
above-identified pending parent application Ser. No. 701,670. Each
six-bit code group is combined in the transmitter with the clock
pulses to produce corresponding six-bit binary codes of the type
comprising "single-height" and "double-height" pulses, but with the
sixth bit zero. Such combining circuitry may be conventional, using
known logical techniques, and thus will not be described herein.
The effect is, however, that each pulse of the original six-bit
code combines with a clock pulse to produce a double-height pulse,
and each "zero" of the original code results in single-height pulse
except that the "zero" of the sixth bit causes a corresponding zero
in the transmitter output.
Referring now to the remote scanner 10 shown in FIG. 3, the pulses
coming in on the return line 28 are directed through a
low-threshold circuit 260 to a clock pulse detector circuit 262.
Clock pulses pass through threshold circuit 260 and operate the
detector 262 which thereupon sets a Read Flop 264 to condition the
scanner to its "Read Mode." In this mode, the scanner is set to
produce scan signals for the computer 50.
The return line 28 also is connected to a high-threshold circuit
266 which passes only the double-height pulses of a received code
group. Such pulses are directed from circuit 266 to a five-bit
register 268 which is stepped by clock pulses from circuit 262, so
that the first five bits of a six-bit code will appear in this
register when the sixth (zero) bit is received. This sixth bit is
detected by circuit 262, which switches the scanner out of "Read
Mode," and simultaneously opens a gate 270 to read out the register
268 to a decoding circuit 272.
If the code in register 268 signifies a command for the scanner to
skip to a subsequent text line on the document, the decoder 272
activates a lead 274 to set a "skip flop" 275. The output of this
flop is one input to a motor control circuit 276 (another input to
which is the end-of-scan signal to index the drum one step between
each sweep of the beam during a reading operation). While the flop
275 is set, the drum stepping motor 278 will operate continuously
to index the document drum 14 at high speed.
Thus the motor 278 will step the drum 14 at maximum speed until the
next command code has been stepped into register 268 and decoded.
If the next code is another skip signal, the motor will continue to
advance the drum for another skip cycle, i.e., the time duration of
a serial six-bit command code. In one embodiment, the time duration
of each code group was 3 milliseconds (for 6 pulses). A typical
skip distance of, say, 1 inch will require that the computer 50
(operating under program control) produce a number of successive
skip commands to advance the document to the required position.
The function signal for the horizontal scan control may
advantageously comprise two or more 6-bit codes, the first code
serving to establish that the signal is for horizontal scan
control, and the second (or others) to define the starting and
ending points of the horizontal scan. The control apparatus for
this purpose is illustrated in FIG. 3 by a block 284 labeled
"Horizontal Scan Control" and containing conventional circuits
responsive to the output signals of the decoder 272 for producing a
scan control signal on lead 286.
For example, the control apparatus circuitry 284 may include a
conventional counter responsive to scan clock pulses. This counter
is activated (i.e., prepared for a counting operation) by a signal
from the first 6-bit code signal signifying a horizontal scan
control command. The counter thereafter may be started counting by
the "start-of-scan" (SOS) signal, which occurs when the laser
scanning beam first begins its sweep across the document. The
counter ultimately will be reset by the "end-of-scan" signal (see
the above-mentioned pending application Ser. No. 701,670) which
occurs, for example, after 1,024 clock pulses have been counted,
for a full sweep across the document.
During the counting operation, the signals developed by decoding
the 6-bit codes subsequent to the first horizontal scan code can be
used to define numbers for comparison with the counter output. Thus
when the counter reaches the number corresponding to the first of
these subsequent codes, a "high" output is produced on line 286.
When the counter reaches the number corresponding to the second
subsequent code, the line 286 goes "low." Thus, an "unblanking"
pulse is developed for output gate 211, defining a starting and
ending position for the horizontal scan segment as the beam sweeps
across the document.
If the decoder 272 receives a code group signaling a change in the
threshold level of the scanning detector, the decoder will produce
a corresponding control signal on a line 290. This line is
connected to the threshold-setting circuit 206 and the control
signal it carries operates, through conventional means such as a
solid-state switch or the like, to change the threshold level of
the detector to a new value, either lighter or darker than the
previous setting. Such a change in the threshold setting involves
conventional electronic techniques, and thus will not be described
in detail herein.
The Field Codes are decoded by the computer 50 in much the same way
as in decoding digits of the ID Number, so as to produce function
signals for carrying out the specific commands concerning the
corresponding data fields. That is, the recognized Field Code
characters are transferred to the storage register 90 for
appropriate processing in accordance with the computer program, and
function signals are developed for the specified commands to aid in
processing the document.
It may be noted that for certain Field Codes, the computer will be
arranged to remember the horizontal location of a control
character, so as to permit identifying the characters in
corresponding fields below that control character. Such horizontal
location can conveniently be derived from the raw data stored in
the decoder scan converter, because the storage position of each
bit of that data identifies a corresponding location for a
character element on the data grid of the original set of scans
through the line of text. Thus when the computer reads out from the
decoder scan converter the data bits for a Field Code character,
and the recognition circuitry 70 determines that the character is a
specified marked control character (such as the 5 in document 100),
the computer will in response to such determination store a
corresponding signal in its memory for use when subsequently
reading and processing the next line of text. That is, for each
character read in the subsequent line, the computer will check to
determine if its location (horizontally) in the decoder scan
converter is that of a previously-identified specially marked
control character. If so, the computer program carries out the
programmed steps, such as placing the recognized number in the
accumulator.
At times, a document may inadvertently be inserted in the scanner
in a skewed position. Thus, the data in the field below a marked
control character may not all appear to be in the same location
(horizontally), raising a possibility that errors will be made in
assigning recognized characters to the proper data field. Such a
problem is avoided in accordance with another feature of this
invention by the use of a distinctive reference mark or "bench
mark," pre-printed on the document in a predetermined position
below a control character. In the document 100, the bench-mark is a
0, shown a little more than half-way down the left-hand side of the
document, and having a predetermined position approximately beneath
the control character 9.
When the scanner reaches the text line containing the 0, it will
transmit that character to the computer 50 along with any other
information characters in the text line. The computer will
recognize the 0 as a bench mark, and will compare its horizontal
position with that of the horizontal position of the corresponding
control character 9. If the 0 is within a specific tolerance with
respect to the 9, the computer will do nothing concerning skew
angle. However, if there is a discrepancy, the computer will
determine the amount of horizontal shift which had appeared, and
will modify the subsequent character analyzing program so as to
offset horizontally the apparent location of information characters
detected in that text line and in subsequent text lines. Thus, the
information characters subsequently will be assigned the correct
horizontal positions with respect to control characters above them
which define the data fields. It may be noted that the actual
amount of horizontal discrepancy will increase for each subsequent
text line, but as a practical matter a fixed amount of horizontal
offset compensation is adequate for most applications.
In addition to the specific commands pertaining to skip distance,
horizontal scan zone, etc., discussed above as specific examples of
the kinds of controls to be effected, the system typically will
include a variety of other functions. For example, the
function-signal generator 250 will be arranged to produce a
specific command to "skip out" the document. Such a command may
consist of a corresponding 6-bit code, followed by a steady stream
of clock pulses to provide phase signals after the document has
been ejected from the scanner; the scanner will be arranged to
ignore the clock pulses, i.e., not to switch to Read Mode, while
the document is being skipped out.
The function-signal generator 250 (i.e., the computer program) also
may be arranged to produce a code commanding the stepping motor 278
to operate in reverse. During such reverse movement, the scanning
will continue and scan signals developed, but no recognition
sequences will be carried out at the central station. After the
scanner has reached the top of the text line, the stepping motor
will stop, and will automatically be started again in forward
direction so as to re-scan the text line involved.
Another important function is that of interrupting stepping of the
drum, e.g., until the computer completes certain processing
precedent to making a decision to proceeed, or to repeat a text
line, or the like. Such a "hold" command, produced by the computer
as a 6-bit code, will be decoded at the scanner and used to
activate a signal blocking the energizing circuit of the stepping
motor 278, in a conventional manner.
The computer also is arranged to produce an "error" signal,
indicating that for some reason the material on the document cannot
be processed. Thus the document should be ejected from the scanner
without further processing, and the operator at the scanner should
attend to the matter, such as by trying the document over again
from the start, or by setting aside the problem document for
examination, and going on to the next document.
In the preferred embodiment, the computer signals an "error" not by
the usual 6-bit code, but by blanking the clock pulses from the
return line 28. The scanner includes a detector 298 responsive,
after a predetermined time delay, to the absence of any signals on
the return line. This detector is operable (through conventional
means, not shown) to direct the motor control circuit 276 to
skip-out the document, and also to actuate an operator alarm, such
as by lighting a red light on the scanner. This error signal also
can be developed manually by the operator at the CRT display unit
86, by actuating a so-called "kill button" when it is clear that
the information read from the document and shown on the CRT cannot
be deciphered.
Although one embodiment of the invention has been decribed in
detail herein, it is to be understood that this is for the purpose
of illustrating the invention and is not to be construed in a
limiting sense; it is clear that many modifications to the
invention can be made by those skilled in the art, based on the
teaching herein, and within the scope of the present invention
which is to be considered limited only by the prior art.
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