JPH0856286A - Image forming device - Google Patents

Abstract

PURPOSE:To detect a copy inhibition mark printed on a document with a simpler constitution and to surely prevent forgery by forming an image at the time of discriminating that image data is equal to image data stored in a storage means. CONSTITUTION:At the time of preparatory scanning, IR data and G data read by a CCD sensor 14 are outputted to a storage processing part 2. At the time of actual scanning, G data read by the CCD sensor 14 is inputted to the storage processing part 2. The storage processing part 2 inputs this G data to a comparison part 3 and outputs G data for preparatory scanning and position information to the comparison part 3. the comparison part 3 extracts G data for actual scanning and compares it with G data for preparatory scanning to discriminate whether they coincide with each other. Only when the discrimination result that the document for actual scanning is equal to that for preparatory scanning is received, picture data read by actual scanning is used to form an image on copy paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a digital color copying machine having a function of preventing forgery of securities such as banknotes and checks.

[0002]

2. Description of the Related Art With the improvement in accuracy of digital color copying machines, forgery of securities such as banknotes and checks has become a problem. In order to cope with this, in the copying machine disclosed in Japanese Patent Laid-Open No. 55-111977, image data of copy prohibited objects such as banknotes, checks, securities, etc. is stored in advance, and the original document is copied during the copying operation. Pattern matching is performed with the image data of the copy prohibited object. here,
If it is determined that the original document is a copy prohibited item, image formation on the copy sheet is prohibited. The prohibited items are:
In addition to the above, coupons, various tickets, stamps, revenue stamps,
Parking tickets are applicable. Further, in the image storage device described in Japanese Patent Laid-Open No. 2-73283, the banknote, the check,
The image data of the copy-prohibited object such as securities is stored in advance, and the image data of the document is pattern-matched with the image data of the copy-prohibited object during the copying operation.
Here, if it is determined that the document corresponds to a copy prohibited item, an invalidation process such as blackening the image printed on the sheet until then is executed.

However, the above-mentioned copying machine requires a large-capacity memory for storing the image data of each copy-inhibited object such as a banknote, a check, and a securities for which copying is prohibited. In addition, since bills and the like are regularly wicketed, it is difficult to deal with them completely. The conventional model in which the image data of the new bill is not input cannot prevent the forgery of the new bill. Some banknotes have light colors or very fine lines that form an image, and it is difficult to reliably and reliably recognize these images. In addition, it is difficult to deal with only banknotes completely, but securities and checks have different designs in banks and the like even in the same country, and it is more difficult to deal with them than banknotes.

Therefore, a mark indicating prohibition of copying is printed on a plurality of places on the surface of the original such as a bill, and the copying operation is prohibited when, for example, two or more copying prohibition marks are detected from the original during copying. Or a system to cancel is proposed. FIG. 1A is an example of a mark indicating copy prohibition (hereinafter, this is referred to as a copy prohibition mark). FIG. 1B is an example in which the copy prohibition mark shown in FIG. 1A is printed on a plurality of places of a bill. If the above-mentioned copy prohibition mark is used, instead of storing the image data of various copy-prohibited objects for which copying is prohibited, it is only necessary to store the data of the mark, and the total amount of data to be stored in the copying machine body is greatly reduced. can do. In addition, pattern matching for fine patterns such as banknotes is not required, and the time required for the matching process can be significantly reduced. In addition, even if a part of the manuscript is hidden by printing the copy prohibition mark on multiple places on the manuscript surface,
Copying of the manuscript can be prohibited. However, since the above-mentioned copy prohibition mark is a visible mark, a paper or the like is attached to the copy prohibition mark portion at the time of copying, and the copy prohibition mark is added to the corresponding portion of the copying machine obtained by the copy, or the copy prohibition mark is prohibited. Forgery can be easily made by attaching a mark. Moreover, it is difficult to accept the visible mark on a bill or the like because of its design. Therefore, if the above-mentioned copy prohibition mark is printed using a colorless and transparent ink that absorbs a predetermined light beam outside the visible region, the following advantages can be obtained. The solid line graph shown in FIG. 2 indicates that each wavelength (n
The reflectance (%) with respect to the light beam of m) is shown. Further, the dotted line graph shows the reflectance (%) with respect to a light beam of each wavelength (nm) of a colorless transparent ink that absorbs infrared rays (does not reflect) (hereinafter referred to as infrared ink). In the figure, the shaded region represents a visible region having a wavelength of about 700 (nm) or less. As shown in the figure, ordinary ink reflects about 70 to 80% of the light rays outside the visible region. The copy prohibition mark printed on a banknote or the like using this colorless and transparent infrared ink is not visually recognized, but is recognized as a negative pattern by a sensor that detects only infrared rays. Since the detection of the copy prohibition mark is not affected by the data in the visible region, it can be performed more accurately. Since the copy prohibition mark printed using this infrared ink is usually invisible, it is possible to prevent fraudulent acts such as printing the mark after the mark is hidden and copied. Further, even when a plurality of copy prohibition marks are printed on the surface of a bill, there is an advantage that the display of the description content such as a bill is not restricted.

[0005]

A sensor for detecting only infrared rays (hereinafter referred to as an IR sensor) is necessary for recognizing a copy prohibition mark printed on a bill or the like with the colorless and transparent infrared ink. is there. FIG. 3 shows the switching mirror 3.
13 is an example of a scanner using the IR sensor 315 and the IR sensor 315. The scanner preliminarily reads the image data of the document in order to detect the size of the document and to perform the stabilization process of the toner density before reading the image data for print processing (hereinafter referred to as main scan). The drive is controlled so as to perform an operation (hereinafter, referred to as a preliminary scan).
The scan operation switching mirror 313 is switched so that the reflected light of the document is incident on the IR sensor 315 during the preliminary scan, and the reflected light of the document is 3 during the subsequent main scan.
The line CCD sensor 314 is switched so as to be incident. When this configuration is adopted, a CCD sensor of 3 lines and a data processing circuit of 3 lines can be used as in the conventional copying machine. However, the IR sensor 314
Since it is necessary to prepare separately, the cost becomes high. Further, since it takes some time to confirm the copy prohibition mark, it becomes possible to place a normal manuscript that can be copied during the preliminary scan and replace the manuscript with a bill or the like during the next printing process. . This makes it impossible to prevent effective forgery of bills and the like.

An object of the present invention is to provide an image forming apparatus which detects a copy prohibition mark printed on a document with a simpler structure and surely prevents forgery.

[0007]

An image forming apparatus according to the present invention comprises a reading means for reading RGB image data of an original, a first storing means for storing a copy prohibition mark, and an image data read by the reading means. 1 detection means for detecting the copy prohibition mark stored in the storage means, second storage means for storing image data of a predetermined portion of the image data read by the reading means, and after reading the image data, Determining means for comparing the image data of the predetermined portion of the image data of the document read by the reading means with the image data stored in the second storage means to determine whether they are the same; The print processing unit that forms an image on a sheet based on the image data of the original read by the reading unit next, and the copy prohibition mark are detected by the detection unit. No, and only when the determination unit determines that the image data of the predetermined portion read by the reading unit is the same as the image data stored in the second storage unit, the print processing unit forms an image. And a control unit.

[0008]

In the image forming apparatus having the above-mentioned structure, the detecting means detects the first data from the image data first read by the reading means.
A copy prohibition mark previously stored in the storage means is detected. The second storage means stores image data of a predetermined portion of the document among the image data. The determining means compares the image data read by the reading means at the predetermined portion of the document after the second time with the image data stored in the second storage means and determines whether or not they are the same. The control unit detects that the copy prohibition mark is not detected by the detection unit,
Further, the printing is performed only when the determination means determines that the image data of the predetermined portion of the original document read first and the image data of the predetermined portion of the image data read from the second time onward are the same. An image is formed on the processing unit. This makes it impossible to replace the original document during the printing process after the detection by the detection unit.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The digital color copying machine of this embodiment will be described below in the following order. (1) Copy prohibition mark (2) Detection of copy prohibition mark and prevention of forgery (3) Digital color copying machine configuration (4) Filter configuration (5) Processing block configuration (6) Flowchart description

(1) Copy prohibition mark Conventionally, as a device having a function of preventing forgery of copy prohibited items such as banknotes, checks, securities, etc., JP-A-55-111
In the copying machine disclosed in Japanese Patent Publication No. 977, image data of copy-prohibited objects such as banknotes, checks, and securities are stored in advance, and during copy operation, the image data of the document is changed to the image data of the copy-prohibited objects. Pattern matching with. In the copying machine, when it is determined that the document corresponds to the copy prohibited item, the image formation on the copy paper is prohibited. In addition,
Other than the above, the copy prohibited items include coupon tickets, various tickets, stamps, revenue stamps, parking tickets, and the like. In addition, Japanese Unexamined Patent Publication
In the image storage device described in Japanese Patent Laid-Open No. 73283, image data of copy prohibited objects such as banknotes, checks, securities, etc. is stored in advance, and image data of a document is prohibited during copy operation. Pattern matching with the image data of the object is performed. If it is determined that the document corresponds to a copy prohibited item, an invalid process such as overwriting solid black on the image printed on the sheet until then is executed.

However, the above-mentioned copying machine requires a large-capacity memory for storing the image data of each copy-inhibited object such as banknotes, checks, securities, etc. for which copying is prohibited. It is difficult to deal completely with bills, etc., since they are regularly ticketed. The conventional model in which the image data of the new bill is not input cannot prevent the forgery of the new bill. In addition, some banknotes have a light color or ones that form an image with very fine lines, and it is difficult to reliably and reliably recognize these images. In this way, it is difficult to fully deal with only banknotes, but securities and checks are
Even in the same country, banks have different designs, which makes it more difficult to handle than banknotes.

Therefore, in the digital copying machine of this embodiment,
The copy prohibition mark is printed at a plurality of locations on the surface of the original such as a bill, and the copying operation is prohibited or stopped when, for example, two or more copy prohibition marks are detected from the original during copying. FIG. 1A shows an example of a copy prohibition mark detected by the copying machine of this embodiment. FIG. 1B is an example in which the copy prohibition mark shown in FIG. 1A is printed on a plurality of places of a bill. If the copy prohibition mark is used, instead of storing the image data of various copy-prohibited objects for which copying is prohibited, only the data of the mark need be stored, and the total amount of data to be stored in the main body of the copying machine is greatly reduced. be able to. Also,
Pattern matching for fine patterns such as banknotes is not necessary, and the time required for the matching process can be significantly reduced. Further, by printing the copy prohibition marks at a plurality of positions on the surface of the original, even if a part of the original is hidden, copying of the original can be prohibited. Further, the copy prohibition mark is printed using a colorless and transparent ink that absorbs a predetermined light beam outside the visible region. The solid line graph shown in FIG. 2 indicates that each wavelength (n
The reflectance (%) with respect to the light beam of m) is shown. Further, the dotted line graph shows the reflectance (%) with respect to a light beam of each wavelength (nm) of a colorless transparent ink that absorbs infrared rays (does not reflect) (hereinafter referred to as infrared ink). In the figure, the shaded region represents a visible region having a wavelength of about 700 (nm) or less. As shown in the figure, ordinary ink reflects about 70 to 80% of the light rays outside the visible region. The copy prohibition mark printed on a banknote or the like using this colorless and transparent infrared ink is not visually recognized, but is recognized as a negative pattern by a sensor that detects only infrared rays. Since the detection of the copy prohibition mark is not affected by the data in the visible region, it can be performed more accurately. Since the copy prohibition mark printed using this infrared ink is usually invisible, it is possible to prevent fraudulent acts such as printing the mark after the mark is hidden and copied. Further, even when a plurality of copy prohibition marks are printed on the surface of a bill, the display of the description contents such as a bill is not restricted. The ink for printing the copy prohibition mark may absorb ultraviolet light as long as it is a light ray outside the visible region. However, it is appropriate to use an ink that absorbs infrared rays because ultraviolet rays are attenuated by the platen glass and erroneous detection is likely to occur, and the human body is adversely affected.

(2) Detection of copy prohibition mark and prevention of forgery Detection of the copy prohibition mark and prevention of forgery are carried out as follows. When first reading the image data of the original,
The copy prohibition mark is detected and the image data of the document at a predetermined position is stored. Then, when the image data of the second and subsequent originals is read, the image data read at the predetermined position and the stored image data are compared to determine whether they are the same. The read image data is read only when the copy prohibition mark is not detected when the image data of the first document is read and the document read after the second time is determined to be the same as the document read first. An image is formed on the copy paper based on the above. As a result, it is possible to effectively prevent counterfeiting of a bill or the like by replacing the original with the copy operation note.

In the case of this embodiment, the copy prohibition mark is printed using infrared ink. A sensor that reacts only to infrared rays (hereinafter referred to as an IR sensor) is required to detect the copy prohibition mark. However, it is not preferable to provide a dedicated IR sensor because the manufacturing cost of the device increases. Therefore, in the copying machine of the present embodiment, as will be described later in detail, the 3-line CCD is used at the time of reading the first original.
The R line of the sensor 14 is covered with a visible light blocking filter 16b, and the line CCD sensor is connected to an infrared sensor (hereinafter,
It is called an IR sensor. ) To detect the copy prohibition mark. The remaining G and B line CCDs
The sensor is covered with an infrared cutoff filter 16a. Of the G data, the data at a predetermined position is stored in the RAM 4 and the position information is stored in the RAM 5. Remaining B
The data is used for detecting the document size, stabilizing the toner density, and the like. As a result, an independent IR sensor for detecting the copy prohibition mark can be eliminated. Hereinafter, the reading operation of the image data of the first original document executed by the copying machine of the present embodiment is referred to as a preliminary scan. When the image data of the original is read for the second time and thereafter, all lines of the 3-line CCD sensor 14 are covered with the infrared cutoff filter 16a, and R,
The image data of each of the G and B components is read. Of the G data of the original read from the second time onward, the data stored in the RAM 5 is compared with the data stored in the RAM 4 to determine whether or not they are the same. Hereinafter, the operation of reading the image data of the original document for the second time and thereafter is referred to as a main scan. An image is formed on a copy sheet only when the copy prohibition mark is not detected during the preliminary scan and it is determined that the image data at a predetermined position is the same in the preliminary scan and the main scan. As a result, it is possible to prevent counterfeiting by replacing the original document with a bill or the like during the copying operation after the preliminary scanning.

(3) Structure of Digital Color Copier FIG. 4 is a sectional view of the structure of the digital color copier. The digital color copying machine is roughly divided into an image reader unit 100 that reads an original image and a main body unit 200 that reproduces the image read by the image reader unit. Scanner 1
Reference numeral 0 denotes an exposure lamp 12 that irradiates a document, a rod lens array 13 that collects reflected light from the document, and a filter 1.
6, and a contact type R, G, B three-line CCD sensor 14 for converting the collected light into an electric signal. The scanner 10 is driven by the motor 11 at the time of reading an original, moves in the direction of the arrow (sub scanning direction), and scans the original placed on the platen 15. Exposure lamp 12
The image of the original surface illuminated by the 3 line CCD sensor 1
Photoelectric conversion is performed at 4. The filter 16 will be described later.
Comprises an infrared cutoff filter 16a and a visible light cutoff filter 16b. The filter 16 is controlled to move right and left between the rod lens array 13 and the CCD sensor by a motor 19. Movement control of the filter 16 by the motor 19 will be described later. Filter CCD sensor 14
The R, G, and B multi-valued electric signals obtained by the above are processed by the read signal processing unit 20 to be yellow (Y), magenta (M),
It is converted to either grayscale data of cyan (C) or black (BK). Next, the print head unit 31 performs correction (γ correction) on the input gradation data according to the gradation characteristics of the photoconductor and dithering as necessary, and then
The corrected image data is D / A converted to generate a laser diode drive signal, and the laser diode in the print head unit 31 is driven by this drive signal.

The print head unit 3 corresponding to the gradation data
The laser beam generated by the laser diode in 1 exposes the photosensitive drum 41 which is rotationally driven through the reflecting mirror 37, as shown by the alternate long and short dash line in FIG. As a result, an image of the original is formed on the photoconductor of the photoconductor drum 41.
The photosensitive drum 41 is irradiated with an eraser lamp 42 and charged by a charging charger 43 before being exposed for each copy. When exposed in this uniformly charged state, an electrostatic latent image is formed on the photosensitive drum 41.
Only one of the yellow, magenta, cyan, and black toner developing devices 45a to 45d is selected to develop the electrostatic latent image on the photosensitive drum 41. The developed image is transferred by the transfer charger 46 onto the copy paper wound around the transfer drum 51.

The above printing process is repeated for yellow (Y), magenta (M), cyan (C) and black (BK). At this time, the scanner 10 repeats the scanning operation in synchronization with the operations of the photosensitive drum 41 and the transfer drum 51. After that, the copy paper is separated from the transfer drum 51 by operating the separation claw 47, is fixed through the fixing device 48, and is discharged to the discharge tray 49. The copy paper is fed from the paper cassette 50, and its tip is chucked by the chucking mechanism 52 on the transfer drum 51 so that the positional deviation does not occur during transfer.

(4) Configuration of Filter The scanner 10 has a filter 16 between the document and the CCD sensor 14. As shown in FIG. 8A, the CCD sensor 14 includes a CCD sensor for reading the R component image data of the RGB image data, a CCD sensor for reading the G component image data, and a line for reading the B component. CCD sensor of. The filter 16 includes an infrared cutoff filter 16a and a visible light cutoff filter 16b as shown in FIG.
It is moved perpendicularly to the optical axis, parallel to the CCD sensor 14, and equidistant.

FIG. 6 is a graph showing the relative sensitivity of the sensor of each line of the 3-line CCD sensor 14 to the incident light wavelength (nm). Hereinafter, the R component of R, G, B digital image data will be referred to as R data, the G component as G data, and the B component as B data. CC of line to read R data
The relative sensitivity of the D sensor is represented by a chain double-dashed line. The relative sensitivity of the CCD sensor on the line for reading the G data is represented by a broken line. The relative sensitivity of the CCD sensor on the line for reading B data is represented by a solid line. As can be seen from the figure, the CCD sensor of the line for reading the R data responds better to infrared light of 800 nm or more than the sensors of the other lines. Therefore, an R line CCD sensor is used to detect the copy prohibition mark printed with infrared ink. The visible light cutoff filter 16b, as shown by the solid line in FIG.
It blocks the visible light region of 800 nm or less and transmits infrared light of 800 nm or more.

In the digital copying machine of the present embodiment, at the time of preliminary scanning, as shown in FIG. 8B, the visible light blocking filter 16b is provided in the CCD sensor of the line for reading the R data.
Then, the CCD sensor on the line for reading the G and B data is covered with the infrared cutoff filter 16a. This makes R
The CCD sensor on the line for reading data is used as an IR sensor. Further, at the time of the main scan, as shown in FIG. 8C, the CCD sensors of all the lines are covered with the infrared cutoff filter 16a. As a result, the 3-line CCD sensor 14 functions as a sensor for reading normal R, G, B data.

(5) Structure of Processing Block FIG. 5 is a diagram showing a processing control block of the main body of the digital copying machine. The scanner 10 is driven and controlled by the CPU 1 provided in the read signal processing unit 20. The data read by the CCD sensor 14 is amplified by the amplifier 17 and then converted into a digital signal by the A / D converter 18. The CPU 1 drives and controls the motor 19 and sets the filter 16 to the CCD sensor 14 at the position shown in FIG. Further, at the time of main scanning, the CCD sensor 14 is set at the position shown in FIG. The IR data and G data read by the CCD sensor 14 during the preliminary scan are stored in the storage processing unit 2
Is output to. The B data is output to the image data processing unit 21.

The storage processing unit 2 sends the IR data input from the CPU 1 to the comparison unit 3 and causes the ROM 6 to output the copy prohibition mark data to the comparison unit 3. Comparison part 3
Pattern-matches the copy prohibition mark in the document from the IR data, and sends the detection result to the CPU 1. The storage processing unit 2 stores, in the RAM 4, data of a predetermined portion of the document in the G data, and stores the position information in the RAM.
Store in 5. On the other hand, the image data processing unit 21 detects the size of the document based on the input B data.

At the time of the main scan, the R, G, and B data read by the CCD sensor 14 are input to the image data processing unit 21 to correct the shading correction and the deviation of the read data caused by the positional deviation of each sensor. rear,
The color conversion processing unit 22 and the UCR / BP processing unit 23 convert the multi-valued image data of any one of the four colors of cyan, magenta, yellow, and black, and then output the multi-valued image data to the print head unit 31. In the print head unit 31, the input color data of cyan, magenta, yellow, or black is modulated into a laser diode drive signal by the modulator 32, and the laser diode 33 emits light. The G data read by the CCD sensor 14 during the main scan is also input to the storage processing unit 2. The storage processing unit 2 inputs the input G data to the comparison unit 3, and at the same time, compares the G data at the time of preliminary scan stored in the RAM 4 and the position information stored in the RAM 5 with each other.
Output. The comparing unit 3 extracts the G data at the time of the main scan of the position corresponding to the position information, and extracts the G data at the time of the preliminary scan.
A comparison is made to determine if they match the data. Then, this comparison determination result is sent to the CPU 1.

As will be described below with reference to a flowchart, the CPU 1 receives the detection result indicating that the copy prohibition mark has not been detected from the comparison unit 3, and the original document in the main scan is the same as the original document in the preliminary scan. Only when the result of the determination that the image is received is received, it is permitted to form an image on a copy sheet using the image data read by the main scan. That is, in cases other than the above, the copy operation is ended and the copy invalidation process is executed.

(6) Description of Flowchart FIG. 9 is a flowchart of the printing process and the forgery prevention process executed by the CPU 1. When detecting the pressing of the copy button, the CPU 1 drives the motor 19 to drive the 3-line CC.
A visible light blocking filter 16a is put on the R data sensor of the D sensor 14 (see FIG. 8B, step S).
100). Next, the motor 11 is driven to move the scanner 10 to start the preliminary scan (step S10).
1). The CPU 1 inputs the B data to the document size detecting section 34 in the image data processing section 21 (step S10).
2). The document size detection unit 34 detects the size of the document based on the input B data. Next, the CPU 1
The G data is input to the storage processing unit 2 and the image data of the document at a predetermined location and its position information are stored (step S103). The storage processing unit 2 stores the G data of the document at a predetermined location in the RAM 4 and stores the position information in the RA.
Store in M5. Next, the CPU 1 inputs the IR data to the storage processing unit 2 and executes the detection of the copy prohibition mark (step S104). The storage processing unit 2 causes the comparison unit 3 to compare the data of the copy prohibition mark from the ROM 6, and
Check if the data of copy prohibition mark exists in the data. Then, this result is transmitted to the CPU 1. Upon receiving the signal indicating that the copy prohibition mark is detected from the comparison unit 3, the CPU 1 ends the copy operation (step S1).
YES at 05) to prevent forgery of bills and the like (step S
107). When the copy prohibition mark is not detected (NO in step S105), the above process is repeatedly executed until the preliminary scan for the entire area of the document is completed (step S106).

After completion of the preliminary scan (step S (106
YES), the motor 19 is driven to remove the visible light cutoff filter 16b covering the R data sensor of the CCD sensor 14 (see FIG. 8C, step S10).
8). Subsequently, the motor 11 is driven to move the scanner 10 to start the main scan (step S10).
9). The R, G, and B data read by the CCD sensor 14 are input to the image data processing unit 21, respectively.
In the image data processing unit 21, shading correction and each C
After correcting the shift of the read data caused by the shift of the position of the CD sensor, the color conversion processing unit 22, the UCR / BP processing unit 23, and the like perform four operations for cyan, magenta, yellow, and black.
After being converted into color image data, the image data is output to the print head unit 31 (step S110). Next, the CPU 1
Data is input to the storage processing unit 2. The storage processing unit 2 inputs the input G data to the comparison unit 3 and also stores the RAM data in the RAM.
No. 4, G data at the time of the preliminary scan, and RA
The position information stored in M5 is output to the comparison unit 3.
The comparison unit 3 extracts the G data at the time of the main scan at the position corresponding to the position information and compares it with the G data at the time of the preliminary scan. Storage processing unit 2 This comparison result is output to the CPU 1 (steps S111 and S112). When the comparison result indicating that the document at the time of preliminary scanning and the document at the time of main scanning are different is input from the storage processing unit 2 (step S113).
NO), cancel the copy operation that is in progress,
The remaining copy paper is painted black (step S11)
4). Further, when receiving the input of the comparison result that the original document in the preliminary scan and the original document in the main scan are the same from the storage processing unit 2 (YES in step S113), the copy operation is continuously executed (step S113). S115 and S
116).

As described above, in the digital color copying machine of this embodiment, the copying operation is performed only when the copy prohibition mark is not detected during the preliminary scanning and it is confirmed that the originals are the same in the preliminary scanning and the main scanning. Run. As a result, it is possible to reliably prevent the forgery from being performed by replacing the original document with a bill or the like after the preliminary scanning. Also,
When the copy prohibition mark is printed using ink such as infrared ink that absorbs light of a specific wavelength other than the visible region, a visible light cutoff filter is attached to the R line sensor of the 3-line CCD sensor. By covering it, the sensor can be used as an IR sensor. As a result, it is not necessary to provide a special IR sensor for detecting the copy prohibition mark, and the manufacturing cost of the copying machine itself can be kept low.

[0028]

In the control section of the image forming apparatus of the present invention, the copy prohibition mark is not detected by the detecting means, and the image data of the predetermined portion of the original to be read next is stored in the second storing means. Only when it is determined that the image data is the same as the image data, the print processing unit causes the image to be formed on the sheet based on the image data of the document read next. Therefore, it is possible to reliably prevent counterfeiting of banknotes, securities, etc. without simultaneously reading the image data for print processing and detecting the copy prohibition mark.

[Brief description of drawings]

FIG. 1A shows an example of a copy prohibition mark detected by the digital color copying machine of this embodiment, and FIG. 1B shows an example of printing the copy prohibition mark on a banknote.

FIG. 2 is a graph showing absorptance (%) of ordinary ink with respect to light rays of respective wavelengths (nm) by a solid line and an absorptance (%) of ink absorbing infrared rays by a dotted line.

FIG. 3 is a diagram illustrating a configuration example of a scanner that detects the copy prohibition mark.

FIG. 4 is a sectional view showing the configuration of a digital color copying machine according to this embodiment.

FIG. 5 is a diagram showing a processing control block of the main body of the digital color copying machine.

FIG. 6 is a diagram showing R, G, which the three-line CCD sensor 14 has.
7 is a graph showing the relative sensitivity of each line of B to the wavelength (nm) of incident light of the CCD sensor.

FIG. 7 is a graph showing a filter characteristic (change in transmittance (%) with respect to incident light wavelength (nm)) of the infrared cutoff filter 16b.

FIG. 8A shows R of the 3-line CCD sensor 14,
FIGS. 6A and 6B are diagrams showing the sensors of the G and B lines, FIG. 9B showing the setting position of the filter 16 during the preliminary scan, and FIG. 9C showing the setting position of the main scan.

FIG. 9 is a processing flowchart executed by the CPU 1 of the main body of the digital color copying machine.

[Explanation of symbols]

 1 ... CPU 2 ... Storage processing unit 3 ... Comparison unit 4 ... Image data RAM 5 ... Position information RAM 6 ... ROM 14 ... 3-line CCD sensor

Claims (1)

[Claims] 1. A reading means for reading RGB image data of a document, a first storage means for storing a copy prohibition mark, and a copy prohibition mark stored in the first storage means from image data read by the reading means. Detecting means for detecting; second storage means for storing image data of a predetermined portion of the image data read by the reading means; and, after reading the image data, image data of an original read by the reading means next. Image data of a predetermined portion and image data stored in the second storage means are compared to determine whether or not they are the same, and image data of a document read by the next reading means. A print processing unit that forms an image on a sheet based on the above, and the copy prohibition mark is not detected by the detection unit and is read by the reading unit. And a control unit that causes the print processing unit to form an image only when the determination unit determines that the image data at the predetermined location is the same as the image data stored in the second storage unit. Image forming apparatus.