Specific document discriminating apparatus and image reading apparatus using it therein

The present invention provides an invisible light image detecting means for detecting an invisible light region image formed by using colorless paint in an invisible light region, and a discriminating means for discriminating a general document from a specific one by using the image data detected by said invisible light image detecting means, thus discrimination between a general document and a specific one being executed accurately and without fail.

TECHNICAL FIELD 
The present invention relates to a specific document discriminating 
apparatus which makes a determination as to whether read image data is a 
specific document or not, and an image reading apparatus using it therein. 
BACKGROUND OF THE INVENTION 
In recent years, in association with progress in the field of image 
processing technology, now it is possible to make so elaborate copies of 
bills that copied bills made by a color copying machine can not be 
distinguished from actual ones. For this reason, now serious efforts are 
made to develop a specific document discriminating apparatus which can 
discriminate specific document of bills, securities and the equivalent for 
preventing the specific document being used for practical purposes. 
In a specific document discriminating apparatus, the technology based on 
the pattern-matching method as described, for instance, in Japanese Patent 
Laid Open Publication No. 83571/1990 with the title of "Image Recognizing 
Apparatus" has generally been used. In this apparatus, determination as to 
whether a document is a specific one or not is made by comparing input 
image data to pattern data registered previously. 
With the conventional type of technology as described above, a particular 
portion of a specific document is read by checking with visible rays, and 
read image data is collated and discriminated by means of the pattern 
matching method, but in this case, however, successful recognition ratio 
is not 100%, and also general document often includes areas similar to the 
specific portion of specific document, so it is not always possible to 
distinguish a specific document from a general document. 
If for instance, a precision in discrimination (a threshold value used for 
discrimination) is raised to prevent a specific document from being 
overlooked, a percentage of error recognition in which a general document 
is read as a specific document increases, and on the contrary if a 
precision in discrimination is lowered to prevent a general document from 
being read as a specific document, a percentage of recognition in which a 
specific document is read as a general document goes higher. It is an 
object of the present invention to make it possible to accurately 
distinguish a specific document from a general document without fail. 
SUMMARY OF THE INVENTION 
In order to achieve the object as described above, the present invention 
provides a specific document discriminating apparatus comprising invisible 
rays region image detecting means for detecting an invisible rays region 
image formed with non-color coating varnish emitting rays in an invisible 
rays area, and discriminating means for making a determination as to 
whether a document is a specific document or not using the image data 
detected by the invisible rays region image detecting means. A specific 
document discriminating apparatus according to the present invention and 
an image reading apparatus using it therein detects a mark (an invisible 
rays region image) put on a specific document with non-color coating 
varnish emitting rays in an invisible rays area (for instance, an infrared 
rays region), and makes a determination as to whether a document is a 
specified one or not using the read image data. With this configuration, 
discrimination between a general document and a specific one can be 
executed accurately. 
Also it is an object of the present invention, in order to achieve the 
object as described above, to provide an image reading apparatus having a 
function to make a determination as to whether read image data is a 
specific document or not comprising infrared rays reading means for 
reading an infrared rays region image formed with non-color coating 
varnish emitting rays in an infrared rays region and discriminating means 
for making a determination as to whether a document is a specific one or 
not using the image data read by the infrared rays reading means. With 
this configuration, discrimination between a general document and a 
specific one can be executed accurately. 
It should be noted that the above-described infrared ray reading means 
preferably comprises a CCD sensor (solid state image pick-up chip) which 
can sense infrared rays. Also the infrared rays reading means should 
preferably comprise a CCD sensor (solid state image pick-up chip) which 
can sense both visible rays and infrared rays. With this configuration, an 
infrared or an ultra-violet ray region image formed by using colorless 
paint in an invisible ray region can accurately be read. 
Also it is preferable that the infrared rays reading means can recognize 
each of infrared rays, R (Red), G (Green), and B (Blue) individually by 
switching a filter. Also when an operation to read an image with visible 
rays is repeated several times, the reading operation by the infrared rays 
reading means is preferably executed in the middle of the operations 
above. With this configuration, replacement of a document with other one 
can be prevented.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Detailed description is made hereinafter for a specific document 
discriminating apparatus according to the present invention and an image 
reading apparatus using it therein with reference to related drawings. 
FIG. 1 is a drawing illustrating the configuration of a scanner in which 
the present invention is implemented, comprising a CCD sensor 101 (charge 
coupled device) into which reflected rays of rays irradiated onto a 
document is supplied as input and which recognizes image data by 
converting the reflected rays to electric signals, a CCD sensor driving 
section 102 which drives the CCD sensor 101, an image processing section 
103 which executes various types of image processing described 
hereinafter, an I/F (interface) controller 104 which outputs the image 
data processed by the image processing section 103 to an external device 
such as a host computer, a specific document discriminating section 105 
which makes a determination as to whether a document is a specific one or 
not, a CPU 106 controlling the entire system, a ROM 107 in which various 
types of programs to be executed by the CPU 106 as well as data are 
stored, a RAM 108 used as a work area, a halogen lamp 109 which is a rays 
source to expose a document to the rays, a lamp driver 110 to drive the 
halogen lamp 109, a stepping motor 111 to move an optical system 
(scanning), a motor driver 112 to drive the stepping motor 111, and an 
operation section 113 for executing a various types of operation. 
FIG. 2 is a drawing illustrating spectral characteristics of R,G,B, and IR 
rays read by the CCD sensor 101. As shown in this figure, the CCD sensor 
101 is a CCD sensor which can sense infrared rays, into which IR (infrared 
rays), R (Red), G (Green) or B (Blue) rays are provided as input, and 
which converts the input rays to electric signals. Herein, the infrared 
ray is defined as light having a wave length of 700 nm or more. 
FIG. 3 is a drawing illustrating the configuration of the specific document 
discriminating section 105, comprising an A/D convertor 301 into which an 
analog signal for IR detected by the CCD sensor 101 is supplied as input 
and which converts the analog signal to a digital signal, a shading 
correcting section 302 which corrects irregularities such as that of 
illumination by a halogen lamp 109 and that of sensitivity of each pixel 
in the CCD sensor 101, a contrast emphasizing section 303 which adjusts 
contrast between a hi-lighted portion and a shadow portion, a sharpness 
correcting/clarifying and noise removing section 304 which executes 
operations for sharpness correction, clarification, and noise removal with 
a smoothing filter and an edge emphasizing filter, a binary coding section 
305 which converts image data to binary coded data, to a pattern collating 
section 306 of which the binary coded image data is supplied as input and 
which collates the image data referring to patterns registered previously, 
and a discriminating section 307 which makes a determination, depending on 
the result of collation by the pattern collating section 306, as to 
whether the image data matches any of the registered patterns or not. 
FIG. 4 is a drawing illustrating configuration of the image processing 
section 103; comprising an A/D convertor 401 to which analog signals for 
R,G, and B detected by the CCD sensor 101 are supplied as input, and which 
converts the analog signals to digital ones, a shading correcting section 
402 which corrects irregularities such as that of illumination by the 
halogen lamp 109 and that of sensitivity of each pixel in the CCD sensor 
101, a density converting section 403 which converts brightness data to 
density data, a black extracting/background color removing section 404 
which extracts black color and removes the background color from the 
density data for R, G and B, a color/tone correcting section 405 which 
corrects colors and tones, a sharpness correcting section 406 which 
executes sharpness correction, and a color converting section 407 which 
converts color data for R, G, and B to Y, M and C respectively. 
FIG. 5(a) and FIG. 5(b) show an optical system in a scanner according to 
Embodiment 1 respectively. In these figures, designated at 501 is a color 
document to be read, which is placed on a document mount contact glass 
502. Light irradiated from the halogen lamp 109 and having a wave length 
up to an infrared rays area is reflected by a document 501 and an image 
formed by the reflected rays is focused on the CCD sensor 101 via a mirror 
503, an individual ray pick-up filter 504, and a lens 505. The individual 
ray pick-up filter 504 comprises 4 filters for IR, R, G, and B as shown in 
FIG. 5(b), and picks up each of IR, R, G and B independently by switching 
these filters. In Embodiment 1, only IR is picked up by the IR filter 1 in 
the first scan, and then the filters 2, 3, and 4 are turned in this order 
in each scan to pick up image data for R, G and B successively. 
Description is made hereinafter for a specific document discriminating 
apparatus having the configuration as described above. When an operator 
places the document 501 on the document mount contact glass 502 and 
presses a start key (not shown) in the operating section 113, the CPU 106 
reads out a control program from the ROM 107 and starts an operation for 
reading an image. 
FIG. 6 is a drawing illustrating a control program, and according to this 
control program, at first the first scan is executed using the IR filter 
of the individual ray pick-up filter 504, and image data in an infrared 
rays region (image formed with non-color coating varnish emitting rays in 
an infrared rays area: described IR data hereinafter) is read by the CCD 
sensor (S601). The IR data in a range from 700 nm to 1000 nm is used. 
Then, the IR data is transferred to the specific document discriminating 
section 105, wherein a processing for discriminating a specific document 
is executed, and the result of discrimination is supplied as input (S602) 
to the CPU 106. 
Next description is made for a processing for discriminating a specific 
document in the specific document discriminating section 105. In the 
specific document discriminating section 105, a specified image processing 
is executed to the IR data by the A/D convertor 301, shading correcting 
section 302, contrast emphasizing section 303, and sharpness 
correcting/clarifying and noise removing section 304, the image data is 
converted to binary coded data by the binary coding section 305, the IR 
data is collated in the pattern collating section 306 by referring to 
pattern data (patterns of infrared rays region images each formed with 
non-color coating varnish emitting rays in an infrared rays region on a 
specified document and registered previously) and also by using the 
pattern matching method, and the result of collation is transferred in a 
form of coincidence rate (adaptation rate) to the discriminating section 
307. 
The result of collation (coincidence rate) by the pattern collating section 
306 is supplied as input to the discriminating section 307, which compares 
the coincidence rate to a threshold value and recognizes the document as a 
specific document if the coincidence rate is more than the threshold 
value, or as a non-specific document if the coincidence rate is smaller 
than the threshold value. It should be noted that, as the threshold value 
for this processing may be set by taking into considerations only the 
processing for discrimination of a specific document, a precision in 
detecting a specific document may be raised. The result of discrimination 
by the discriminating section 307 is transferred to the CPU 106. 
Upon input of the result of discrimination by the discriminating section 
307 in the specific document discriminating section 105, the CPU 106 makes 
a determination as to whether the document is a specific one or not 
(S603), inhibits an operation for recognition by a scanner by controlling 
the CCD driving section 102, lamp driver 110, and motor driver 112 (S604), 
and displays a message such as "Document inhibited to be read. Change the 
document" on a display panel (not shown) in the operating section 113 
(S605), thus the processing being finished. 
On the other hand, if the document is not a specific one, then, 
determination is executed as to whether the document pressing plate has 
been opened or not (S603a), and if it is determined that the document 
pressing plate has been opened, a message such as "Close the document 
pressing plate during scanning" is displayed (S603b), and the system 
control returns to Step S601. On the contrary, if it is determined that 
the document pressing plate has not been opened, the second scan is 
executed by using the R filter in the individual ray pick-up filter to 
read R data (image data for red color) with the CCD sensor 101, and a 
specific image processing is executed to the read R data in the image 
processing section 103 to convert the R data to C data (S607), which is 
then provided as output via the I/F controller 104 to an external device 
(S608). 
Then the individual ray pick-up filter 504 is switched to the G filter and 
the third scan is executed to recognize G data (image data for green 
color) with the CCD sensor 101 (S609), and a specified image processing is 
executed to the read G data in the image processing section 103 to convert 
the G data to M data (S610), which is provided as output via the I/F 
controller 104 to an external device (S611). 
Then, the individual ray pick-up filter 504 is switched to the B filter, 
the fourth scan is executed to recognize the B data (image data for blue 
color) with the CCD sensor 101 (S612), and a specified image processing is 
executed to the B data in the image processing section 103 to convert the 
B data to Y data (S613), which is provided as output via the I/F 
controller 104 to an external device (S614), thus the processing being 
finished. 
As described above, in Embodiment 1, determination as to whether a document 
is a specific one or not is made depending on image data (IR data) read by 
the CCD sensor 101 and the IR filter of the individual ray pick-up filter 
504, so that a specific document can be distinguished from a general 
document accurately without fail. 
In Embodiment 2 of the present invention, a CCD sensor which can sense R, B 
and G rays with a section sensing R which has also a sensitivity for IR is 
used in place of the CCD sensor 101 used in Embodiment 1. Also a filter 
701 as shown in FIG. 7 is used in place of the individual ray pick-up 
filter 504. Other portions in this configuration are the same as those in 
Embodiment 1, so description and drawings concerning the portions are 
omitted herein. 
Description is made below for operations of a specific document 
discriminating apparatus according to Embodiment 2 of the present 
invention having the configuration as described above. FIG. 8 is a 
flowchart illustrating a control program according to Embodiment 2. At 
first, the first scan is executed using the IR filter of a filter 701, and 
ID data is read by a CCD sensor (not shown), R sensing section of which 
has also a sensitivity for rays in an IR region (S801). Then, the read IR 
data is transferred to the specific document discriminating section 105, 
wherein a processing for discriminating a specific document is executed 
and the result of discrimination is supplied as input to the CPU 106 
(S802). 
When a result of discrimination is supplied as input from the 
discriminating section 307 of the specific document discriminating section 
105, the CPU 106 executes a processing for determination as to whether a 
document is a specific one or not (S803), and if the document is a 
specific one, the CPU 106 inhibits operation of a scanner for recognition 
by controlling the CCD driving section 102, a lamp driver 110, and a motor 
driver 112 (S804), and displays a message such as "Document inhibited to 
be read. Change the document" on a display panel (not shown) of the 
operating section 113 (S805), thus the processing being finished. 
If the document is not a specific document, the second scan is executed 
using the IR cut filter of the filter 701 to recognize RGB image data with 
a CCD sensor (S806), a specified image processing is executed to the read 
RGB image data in the image processing section 103 to convert the image 
data to YMC data (S807), which is provided as output via the I/F 
controller 104 to an external device (S808), thus the processing being 
finished. Also in Embodiment 2, the same effect as that in Embodiment 1 
can be achieved. 
In Embodiment 3 of the present invention, an individual ray pick-up filter 
901 as shown in FIG. 9 is used in place of the individual ray pick-up 
filter 504 in Embodiment 1, an operation for reading IR data is executed 
in the middle of repetition of an operation for recognition with visible 
rays. It should be noted that, as the basic configuration and the basic 
operations are the same as those in Embodiment 1, description is made 
below for only different portions. 
As shown in FIG. 9, an individual ray pick-up filter 901 consists of 4 
filters for R, IR, G and B rays, and each of R, IR, G and B rays is picked 
up individually by switching these filters. At first, only R rays are 
picked up by the R filter indicated by the reference numeral 1 during the 
first scan, and then the filter is turned during each scan in the order of 
2, 3 and 4 to pick up image data for IR, G and B in this order. 
FIG. 10 is a drawing illustrating a control program according to Embodiment 
3. At first, the first scan is executed using the R filter of an 
individual ray pick-up filter 901 to recognize R data with the CCD scanner 
101 (S1001), and a specified image processing is executed to the read R 
data in the image processing section 103 to convert the R data to C data 
(S1002), which is provided as output via the I/F controller 104 to an 
external device (S1003). 
Then the second scan is executed using the IR filter of the individual ray 
pick-up filter 901 to recognize IR data with the CCD sensor 101 (S1004), 
and the read data is transferred to the specific document discriminating 
section 105, wherein a processing for discriminating a specific document 
is executed, and the result of discrimination is supplied as input 
(S1005). 
Upon input of the result of discrimination from the discriminating section 
307 of the specific document discriminating section 105, the CPU 106 makes 
a determination as to whether a document is a specific one or not (S1006), 
and if the document is a specific one, the CPU 106 inhibits a scanner's 
operation for recognition by controlling the CCD driving section 102, lamp 
driver 110, and motor driver 112 (S1007), and displays a message such as 
"Document inhibited to be read. Change the document" on a display panel 
(not shown) of the operating section 113 (S1008), thus the processing is 
finished. 
If the document is not a specific one, the individual ray pick-up filter 
901 is switched to the G filter, the third scan is executed to recognize G 
data with the CCD sensor 101 (S1009), and a specified image processing is 
executed to the read G data in the image processing section 103 to convert 
the G data to M data (S1010), which is provided as output via the I/F 
controller to an external device (S1011). 
Then, the individual ray pick-up filter 901 is switched to the B filter, 
the fourth scan be executed to recognize B data with the CCD sensor 101 
(S1012), and a specified image processing is executed to the read B data 
in the image processing section 103 to convert the B data to Y data 
(S1013), which is provided as output via the I/F controller 104 to an 
external device (S1014), thus the processing being finished. 
In Embodiment 3, after R data is read in the first scan, IR data is read in 
the second scan to make a determination as to whether a document is a 
specific one or not, and then G data and B data are read, so that it is 
possible to make an accurate determination as to whether a document read 
by a scanner is a specific one or not without fail. In other words, if IR 
data is read in the first scan to make a determination as to whether a 
document is a specific one or not, there is a possibility that the 
document may be exchanged with a new one before start of the second scan, 
but in Embodiment 3, the possibility for a document to be exchanged with a 
new one is eliminated. It should be noted that, even if a scan with the IR 
filter is executed in the third scan, the same effect can be achieved, but 
in this case it takes along time to make a determination as to whether a 
document is a specific one or not, and for this reason the best mode for 
carrying out the present invention is to execute scan with the IR filter 
in the second scan. 
It should be noted that, although infrared rays are used as invisible rays 
in any of Embodiments 1 to 3 above, the same effect can be achieved by 
using ultra-violet rays. Herein, the ultra-violet ray is defined as light 
having the wave length of 400 nm or below. 
AVAILABILITY FOR INDUSTRIAL PURPOSE 
As described above, the specific document discriminating apparatus 
according to the present invention and the image reading apparatus using 
the same are mounted in an image forming apparatus such as a coping 
machine, or a printer, and can advantageously be used for discriminating 
specific documents such as bills and securities placed on the image 
forming apparatus and preventing the specific documents from being copied 
illegally.