Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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1 This invention rel~tes ~o an opti.cal character
reader for reading with accuracy characters or symbols
entered in a form~
~ig~ 1 i.s a plan vie~l explanatory or read-scanni.ng
characters on a form,
Fig. 2 ;.s. a perspective schemati.c vi.ew of an
opti.cal c~aracter reader of the i.nvention when in use,
F~g. 3 i.s a plan vi.ew of a picture of an image
sensor at the same, and
Fig. 4 i5 a circuit diagram of a detection c~rcuit
for detecting the form
Generally, the optical charactex reader scans
characters entered in the ~orm, images the charactexs
through a lens system on an image sensor compr~.sing a photo-
, 15 electric conversion.element, converts by a binary circuit
analog signals from the image sensor into binary signalscorrespondîng to the background region and characters on
the form and discriminates ~y a discrimination ci.rcuit the
binary signals as the characters on the form. For reading
the characters given on the forms~ such as slips or price
tags, a hand~scan type optical character reader (to be
herei.nafter called the hand scan OCR~ which hand-operates
a scanning unit and a stationary type optical character
reader ~to be hereînafter called the stationary OCR)
which fixes the scanning uni.t and transports the form, are
used. These OCR~s as shown i.n F~.g 1, sc.ans object
ch~racters 13 to be read and entered in the form 11,
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1 r;ghtwardly or le~t~ardly i`n the directions of the arxows
in the dra~ing~ ther,e~y carry~.ng out the readi.ng operat~.on~
However, when the characters 13 on the ~orm 11
~re read~ a scanner 14 after moves from the base out of
the form 1.1 toward the ch~racter line. thereon beyond the
ed~e 12 of form 11, ~hRreby there is a fear of reading un~
necessary characters or symbols out of th.e form 11 ~on the
base). carrying the object characters 13 to be read. Also,
si,nce the edges 12 o~ form 11 are liable to be optically
shaded~ the shade will be read ~y mistake~ Furthermore~
in a case where t~e. edges 12 oE form 11 are close to the
object characters 13 to be readl the character 13 have
. often ~een misread.
In the light of the above problems, this i,nvent;on
; 15 has been designed, An o~ject of the invention is'to pro-
vide an optical character reader which prevents misreading
of the edges of the form or chc~racters or symbols not
th,ereon, thereby enabling reliable read of the object
characters entered in the form onl~
The above and ot.her objects and features of the
i,nvention ~ill appear more fully hereinafter from a con-
sideration of the follow;ng description taken in connection
with the accompanying drawing wherein one example i,s illus- -
trated by way o~ example~
The opti.cal character reader of the invention!
as shown in F;g. 2, provides a b~se 21 for placing thereon
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1 a ~orm 11, i.n which ob~ect characters 13 to be read are
entered ! the base 21 usi.ng a metal plate painted black or
the like so as to have a reflection factor lowe~ (for
example, 2% or less~ than that of form 11 (usually~ 70%
S or moxe because of the use of the white form~ Alternatively,
a member, such. as a hollow ~arrel holdîng the form at ~oth
vertical edges thereo~ of reflection factor lo~er than
that of the form may be substituted for the base 21.
The scanner 14 houses therein an image sensor
. 10. ~photoelectric conversi.on element~ ~y whïch images 22
formed through the lens system are converted into analog
electri.c si.gnals, the image sensor ~eing utilized to
provide a circuit for detecting the form 11. In addition,
a picture of the image sensor, on which.the image 22 i.s
formed, is shown in Fig~ 3! and the detection ci.rcuit i~s
shown in Fig. 4.
The detectinn circuit for t~e orm, as sho~n in
Figs. 3 and 4, comprises the ma~imum black line detection
~3
.4 ~t~ ,91 ql~4
Y~
l OR circuit I detecting the maximum lines including
black portions~among the respective lines at the
picture 23 of image sensor, a reflection factor comparison
circuit II which compa~es whether the reflection factor
of the maximum black lines detected by the maximum
black line detection OR circuit I corresponds to that
of the form, and a character level detection-elimination
circu~t III which compares whether the sum of the
maxirnum black lines is smaller than the level correspond-
ing to the characters 13 entered in the form ll 50 that a
reading command signal a is output only when the same
is lower than the level.
The maximum black line detection OR circuit I
comprises a resistance R1 through which a comparison
circuit A is connected with a power source and diode~
D1 and Dn throu~h which the imput terminal of comparator
A is connected to both lateral end lines V1 and Vn at the
picture 23 of image sensor respecti~ely as shown in
Fig. 3. In addition, in this case, the diodes D1 and Dn
. may be connected to lines deemed neccessary other than
both the lateral end lines. In such circuit I, the
comparator A is given analog electric si~nals from the
maximum black lines of the maximum black portions.
The reflection factor comparison circuit II sets
at the minus input terminal of a comparator A reference
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l potential corresponding to the reflection factor of
the form 11 through voltage dividing resistances R2
and ~3 so that the reflection factors given into the
plus input terminal of the comparator A are compared
in order of each line whether or not the reflection
factors corresponds to that of form 11, thereby outputt-
ing the black portion of higher level than reference
potential only from the comparator A.
The character level detection ~limination circuit
III includes an integration circuit comprising a
resistance R4 and a capacitor C1, through which integra-
tion circuit the output line of comparator A is connectecl
with an input terminal at a comparator B, the integration
circuit integrating the black portions of the maximum
black lines output from the comparator A. Also, at the
minus inpu~ terrninal of comparator B, voltaye dividing
resistance RS and R6 set reference voltage correspond-
ing to the level of characters 13 entered in the form 11
~hereby a read command sic3nal a is output from the
comparator B only when the sum of black portions is
lower than the reference potential. In other words,
since the sum of black portions in the lines is integrated
by the integration circuit, the levels of the black
portions are measurable. Also, the comparator B
compares the level of Dlack portion with the character
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l level set by the reference potential so that only
when the su~ o~ black ~ortions is smaller than the set
value, the comparator B will output the read command
signal a to discrimination circuit IV~ ~hich i.s housed
in the reader, decides whether or not the discrimination
result read rom the scanner 14 is adopted, and is
controlled by the read command signal a given from the
comparator B.
Accordinyly, when one latèral end line at the
picture 23 of image sensor is positioned on the b~ack
base 21, the read command signal a is not yiven and the
character images 22 forMed on the picture 23 of ima~e
sensor axe not read. In other owrds, the readin~
operation starts after the imaging picture 23 of
image sensor is positioned to completely meet with the
form 11, and continues until the read com~and signal a
is eliminated, thereby enabling preventiny of misread-
ing out of the form 11~ As a result, although the
convention reader has hitherto misread abo~t 10 of 500
sli~s, the reader of the invention has done nothing~
Alternatively, the aforesaid circuit may be
constructed ofr white portions in the lines. Also,
the present invention may of course be applicable to
a hand scan OCR manually operating the scanner for
scanning the characters, or a stationary type OCR
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1 which fixes the scanner and moves the form for scanning.
As seen frpm the above, this invention carries
out reading operation only when the image-formation
screen of image sensor at the sc~ner is positioned
completely on the form, so that there is no fear of
reading by mistake the edges of the form or characters`
and symbols not therein, thereby prPvPnting mlsreading,
thus havin~ enabled a large improvement in reading
performance.
While an embodiment of the invention has been
shown and described, the invention is not limited to
the specific construction thereof, which is merely
exernplary in the specifica~ion rather than defined.
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