JPH0787296A - Picture forming device - Google Patents

Abstract

PURPOSE:To exactly form a picture with a high quality, and to prevent the forgery of securities without disturbing information peculiar to a picture forming device by adding the information peculiar to the picture forming device at the time of final picture formation. CONSTITUTION:The information (device number pattern) peculiar to the picture forming device is generated by a device number pattern generating circuit 15, the device number pattern is modulated by a modulating amount control circuit 16 according to an optimal modulating amount calculated by a CPU 107, and the modulated device number pattern is synthesized with a picture signal by a comparator circuit 19. The picture signal on which the device number pattern is superimposed is modulated by a pulse width conversion circuit 20 so as to be a laser emitting time in proportion to a density signal, transmitted to a laser driver circuit 21, and a multilevel image is formed. Thus, after a full-color picture is formed, it is observed through a sharp band filter, so that the device number pattern can be discriminated, and even when the forgery is committed, the device by which the forgery is committed can be specified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to an image forming apparatus for finally transferring an image formed on an image bearing member onto a recording material to obtain an image, and in particular, performing image formation plural times. The present invention relates to an image forming apparatus that forms a color image by superposing color images formed of color materials of a plurality of colors.

[0002]

2. Description of the Related Art Conventionally, various measures have been proposed in order to prevent counterfeiting of securities using a color image forming apparatus. One of the methods is a method of superimposing (adding) a symbol unique to the image forming apparatus, which is difficult to be visually recognized, on the image information with a constant modulation amount in order to specify the image forming apparatus used for forgery.

That is, if securities are counterfeited using such an image forming apparatus, the symbol unique to the image forming apparatus formed on the counterfeit article is extracted only in a specific wavelength range. If you read it using a reading device that can
It is possible to specify the image forming device used for counterfeiting,
It is a useful clue for tracking forgers.

[0004]

However, when the above technique is applied to an electrophotographic full-color image forming apparatus, a color material, an electrostatic latent image formed on a photoconductor, which is an image carrier, That is, since the process of electrically attaching toner to form a toner image and then electrically transferring the toner image to a final recording material such as paper is performed a plurality of times, the image forming conditions up to the final image output are set. A symbol (pattern) peculiar to a particular image forming apparatus written during image formation due to fluctuation disappears or becomes unreadable, or in the image of the recording material,
There is a drawback that this pattern is printed in a visible state.

That is, when the toner image electrostatically transferred onto the recording material or the like comes into contact with the photosensitive member again in the subsequent image forming step, the toner image on the recording material is physically removed. Not only is there a possibility that the toner will be peeled off to the photoconductor side due to the adhesive force, etc. The pattern to be made possible is printed in a visible state.

Further, even if there is no peeling as described above after the pattern is formed, the pattern may be deformed when a difference in moving speed occurs between the recording material and the photoconductor.

Therefore, an object of the present invention is to accurately form a high quality image on a recording material, which is a final color image carrier, without disturbing a symbol (pattern) specific to the image forming apparatus. An object of the present invention is to provide an image forming apparatus useful for preventing counterfeiting of securities.

[0008]

The above object can be achieved by an image forming apparatus according to the present invention. In summary, the present invention is
In an image forming apparatus that forms a color image by performing image formation a plurality of times and superposing color images formed of color materials of a plurality of colors, an addition unit that adds information specific to the image forming apparatus to a color image of a specific color. The image forming apparatus is characterized in that the image formation of the specific color to which this information is added is performed at the final image formation.

Preferably, the color images formed by a plurality of color materials are superposed on an intermediate transfer member mainly composed of a resin film, and the color image is transferred to the final recording material by adding the above-mentioned information addition image. It is done after formation.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

Embodiment 1 FIG. 2 shows an example of a color electrophotographic copying apparatus which is an embodiment of the image forming apparatus of the present invention.

In the present embodiment, in the color electrophotographic copying apparatus, the photosensitive drum 4, which is an image bearing member, is rotatably supported in the direction of the arrow and is preliminarily cleaned by the cleaning blade 110, and then uniformly charged by the charger 109. Be charged.

On the other hand, the original 101 placed on the original table glass 102 is CC-illuminated by the light source 103 and the optical lens 104.
An image is formed on D105 and converted into an image signal according to the amount of received light. Although the image signal will be described in detail later, after the image signal is processed by the image signal processing device including the A / D converter 106, the CPU 107, etc., the laser light source 108 is driven, and the emitted laser light is a polygon mirror. It is irradiated onto the photosensitive drum 4 via the mirror 1 and the mirror 2.

According to this embodiment, first, a Bk (black) image signal is image-processed and irradiated on the photosensitive drum 4, whereby a black latent image is formed on the photosensitive drum 4. To be done.

In this embodiment, four kinds of color toners (yellow, cyan, magenta, and
Black) developing devices 3Y, 3M, 3C, 3Bk
Is fixedly installed. First, the latent image is developed by a black developing device 3Bk having a black coloring material to form a black toner image.

Further, the photosensitive drum 4 is rotated, and the toner image formed on the photosensitive drum 4 by the transfer charger 114 is transferred onto the intermediate transfer member 5.

Next, a latent image is formed with an M (magenta) image signal, development is performed by a magenta developing device 3M having a magenta coloring material, and then the formed magenta toner image is aligned. The image is transferred onto the black image on the intermediate transfer member 5 in an overlapping manner.

Similarly, image signals of C (cyan) and Y (yellow) are formed in the same manner, multiple transfer is performed on the intermediate transfer body 5, and four color images are superposed on the intermediate transfer body 5. To form a color image.

Next, the color image on the intermediate transfer member 5 is
Under the action of the transfer roller 8, it is collectively transferred to the recording material 6 such as transfer paper, which is the final color image carrier.
Then, the recording material 6 is separated from the intermediate transfer body 5 and conveyed to the fixing roller pair 7, so that the color image on the recording material 6 becomes a permanent image.

FIG. 1 is a block diagram of an image signal processing apparatus for obtaining a gradation image according to this embodiment.

As described above, the original image is the CCD 105.
Is converted into an image signal (luminance signal) according to the amount of received light at
The brightness signal is converted into a digital brightness signal by the A / D conversion circuit 106.

The obtained brightness signal has its sensitivity variation corrected by the shading circuit 12, and the corrected brightness signal is converted into a density signal by the LOG conversion circuit 13. Furthermore, the γ characteristic of the printer at the time of initial setting is set so that the original image density and the output image match.
It is converted at T (lookup table) 14.

On the other hand, by the machine number pattern generation circuit 15,
Generates a machine-specific signal (machine number pattern). In this embodiment, a machine number pattern, which is a numerical pattern as shown in FIG. 3, is superimposed and added to the Y (yellow) image signal having the lowest resolution visually.

In the present embodiment, as the machine number pattern, the machine number is made to correspond to the number pattern as described above, but it is preferable to employ a pattern corresponding to numbers and characters which is inconspicuous.

In order to calculate the modulation amount of the machine number pattern to be superimposed, the signal from the sensor 112 which measures the reflected light amount of the patch pattern on the photosensitive drum 4 is converted into a digital signal by the A / D conversion circuit 113, CPU107
Sent to. The optimum modulation amount calculated by the CPU 107 is delivered to the modulation amount control circuit 16, and the modulation amount control circuit 16 modulates the machine number pattern. The modulated machine number pattern is combined with the image signal by the comparator circuit 19.

The image signal on which the machine number pattern is superimposed is then modulated by the pulse width conversion circuit 20 so that the laser emission time is proportional to the density signal, and then sent to the laser driver circuit 21 to display the density gradation. By expressing the area gradation, a gradation image is formed.

As described above, according to the present invention, it is possible to separate only the yellow signal by observing through a 350 nm sharp band filter after a full-color image is formed, whereby the machine number pattern can be read. It is possible, and even if the counterfeiting is performed, it is possible to specify which machine performed the counterfeiting.

As described above, according to the present invention, the specific machine number pattern is performed at the final image forming step, and the effect brought by it will be described below.

According to the present invention, when the intermediate transfer member 5 is used for color superposition as in the present embodiment, four times during image formation,
Further, since electric charging is performed once at the time of batch transfer, the intermediate transfer body 5 is required to have an appropriate electric resistance. Therefore, typically, carbon is dispersed in a resin such as polycarbonate to have a volume resistivity of 10 ⁸ to 10 ^8.
It is preferable to use a plastic film set to ¹⁰ Ω · cm.

Further, in this embodiment, in order to transfer all the four color toner images to the recording material 6 by one-time electrostatic transfer by batch transfer, the surface of the film used has a Beck smoothness. It is a very smooth surface for 200 seconds or more and 1000 seconds or less, and the contained carbon improves the releasability of the toner.

That is, when a toner image is formed on such an intermediate transfer body 5 and a Y (yellow) image containing a specific machine number pattern is formed for the first color, the photosensitive drums 4 for the second to fourth colors are formed. At the time of transfer to the intermediate transfer body 5, the toner image of a specific pattern comes into contact with the photoconductor drum 4 and is stripped off substantially layer by layer, and the toner image gradually becomes thin. According to the experiments conducted by the present inventors, in the case of the first color, when two to three layers are formed with the toner having the volume average particle diameter of 6 μm using the specific pattern formed on the white background as the toner layer, after the final image formation, It is almost gone.

Further, in order to prevent this, when a specific pattern is formed with a larger amount of toner, when another color toner is superposed on the specific pattern during the second and subsequent image formation, this portion is reversed. Was confirmed to be conspicuous. When this pattern is formed for the second color or the third color, the degree of residual of the specific pattern is better than that for the first color, but the intermediate transfer body 5 is smooth, and therefore it is specified in the transfer area with the photosensitive drum 4. The pattern collapsed due to the contact pressure, the actual pattern density decreased, and it was difficult to read from the output image.

That is, in an apparatus using such an intermediate transfer member 5 having smoothness and good releasability for multiple transfer, the printing of the forgery preventing specific pattern is performed at the final stage of image formation as in the present invention. is necessary.

Next, a method of superimposing (adding) a specific machine number pattern on an image will be described in more detail.

Image Scanner FIG. 4 is a block diagram showing a configuration example of the image scanner 2201. In this embodiment, a CCD sensor (solid-state image sensor) 1210-having R, G, B spectral sensitivity characteristics
1, 1210-2, 1210-3 are CCs shown in FIG.
D, that is, built in the three-line sensor 105, outputs A / D-converted signals of, for example, 8 bits. Therefore, the R, G, and B colors are classified into stages of 0 to 255 according to the respective light intensities.

Since the CCD sensors 1210-1, 2 and 3 are arranged at a fixed distance, the delay element 1
The spatial shift is corrected using 401 and 1402.

Logarithmic converters 1403, 1404, 1405
Is a ROM or RAM lookup table, and converts the image data sent from the 3-line sensor 105 from a luminance signal to a density signal. The masking / UCR (undercolor removal) circuit 1406 is well known, and its detailed description is omitted.
3, 1404, 1405 from the three signals input,
Each signal of M (magenta), C (cyan), Y (yellow), and Bk (black) for output is output in a frame-sequential manner at a predetermined bit length such as 8 bits for each reading operation. To do.

Masking / UCR (undercolor removal) circuit 14
The output signal from 06 is a known spatial filter circuit 140.
7, the spatial frequency is corrected, and then the density conversion circuit 14
At 08, the density characteristic of the printer is corrected. The density conversion circuit 1408 has the same R as the logarithmic converters 1403 to 1405.
It is composed of OM or RAM.

A pattern adding circuit 1410 for adding a pattern to an output image is connected to the density converting circuit 1408.

On the other hand, the CPU 1411 (C in FIGS. 1 and 2)
It corresponds to the PU 107. ) Controls the control of this embodiment,
The I / O port 1412 is connected.

Here, the masking / UCR circuit 1406
A signal CNO separately input to the pattern adding circuit 1410 is a 2-bit output color selection signal, an example of which is shown in Table 1, is generated from the CPU 1411 via the I / O port 1412, and indicates the sequence of four transfer operations. By controlling, the operating conditions of the masking / UCR circuit 1406 and the pattern adding circuit 1410 are switched.

[0042]

[Table 1]

The CPU 1411 is the photodiode 11
The value of the register 831 for setting the pattern modulation amount is rewritten according to the data from 2.

Pattern Adding Method First, an example of a method of adding a machine number pattern in this embodiment will be described.

FIG. 5 is a diagram for explaining an example of the additional pattern of this embodiment. In this embodiment, the 4 × 4 pixels included in the area 301 are modulated so that, for example, the gradation of the image signal becomes + α, and the 2 × 4 pixels included in the areas 302 and 303 respectively correspond to the image signal. For example, the gradation is -α
The pixels outside the regions 301 to 303 are not modulated. 8x included in the areas 301 to 303
Four pixels are set as unit dots of the additional pattern.

In this way, 8 × is added to one unit of the additional pattern.
The reason why four pixels are used is that the copying apparatus of this embodiment performs the 200-line processing in the known image area, and it may be difficult to read the additional pattern if the unit of the additional pattern is one pixel. Is.

FIG. 6 and FIG. 7 are diagrams showing an example of the add-on line of this embodiment.

In FIG. 6, the add-on line 401 is
For example, the width is 4 pixels. Here, reference numbers 401a to
401e is the unit dot shown in FIG. 5, which is, for example, 8 × 4 pixels. Unit dots 401a to 401e
Are arranged in a substantially constant cycle in the main scanning direction d1 (for example, 128 pixels).

Furthermore, in FIG.
1 to 510 have a width of, for example, 4 pixels, and are arranged in the sub-scanning direction at a substantially constant period of d2 (for example, 16 pixels). Although details will be described later, for example, one add-online represents 4-bit information, and 8 of the add-on lines 502 to 509.
A pair of add-on books can represent 32-bit additional information. The add-on lines are repeatedly formed in the sub-scanning direction. For example, the add-on lines 501 and 509 shown in FIG. 7 represent the same information.

8 and 9 show an example of a method of expressing information by add online.

In FIG. 8, add-on lines 601 and 6 are added.
02 are adjacent to each other in the sub-scanning direction. Also, reference numeral 60
1a, 601b, and 602a are unit dots, and in order to prevent adjacent ad-online unit dot comrades from approaching and conspicuous, adjacent ad-online unit dot comrades are
The distance is set to be at least d3 (for example, 32 pixels) in the main scanning direction.

The data represented by the unit dot is determined by the phase difference between the unit dot 602a and the unit dot 601a. Although FIG. 8 shows an example of representing 4-bit information, in FIG. 8, the unit dot 602a represents data “2”. For example, the unit dot 602a
Is at the leftmost end, data “0” is set to the unit dot 602a.
If is at the rightmost end, it represents the data'F '.

In FIG. 9, of the set of add-on lines representing all the additional information, FIG. 9A shows the first add-on line Line0, and FIG. 9B shows the fourth add-on line Line3.

As shown in FIG. 9, in Line 0, d is displayed on the right side of all the original unit dots 701a to 701d.
Dots 702a to 702 at intervals of 4 (for example, 16 pixels)
d is added, and the original unit dot 70 is added to Line3.
Dots 705a to 705d are added to the right side of all of 4a to 704d at intervals of d5 (for example, 32 pixels). This additional dot is a marker for clarifying the order of each ad online. The reason why the markers are added to the two add-on lines is that the upper and lower sides in the sub-scanning direction can be determined even from the output image.

Further, for example, the pattern to be added is only added with the Y toner by utilizing the fact that the human eye has a low discrimination ability with respect to the pattern drawn with the Y (yellow) toner.

Further, the dot interval in the main scanning direction of the additional pattern and the repeating interval of all the additional information in the sub scanning direction are the thin and uniform areas in which the dots can be reliably identified in the particular document of interest. , It is necessary to ensure that all information is added. As a guide, information may be added at a pitch that is ½ or less of the width of a thin and uniform area that allows dots to be reliably identified in the target specific document.

Pattern Addition Circuit Next, an example of the pattern addition circuit 1410 of this embodiment will be described.

FIG. 10, FIG. 11 and FIG. 12 are block diagrams showing configuration examples of the pattern adding circuit 1410.

In this embodiment, in FIG. 10, the sub-scanning counter 819 repeatedly counts the main scanning synchronizing signal HSYNC and the main scanning counter 814 repeatedly counts the pixel synchronizing signal CLK with a 7-bit width, that is, 128 cycles. AND connected to the outputs Q2 and Q3 of the sub-scanning counter 819
The gate 820 outputs H when both the bit 2 and the bit 3 of the sub-scanning counter 819 are H. That is, the output of the AND gate 820 becomes H for a period of 4 lines for every 16 lines in the sub-scanning direction, and this is used as an add-on enable signal.

Further, the enable signal Line0 of the add-on line 0 is generated by the gate 822 which inputs the output of the AND gate 820 and the upper 3 bits (Q4 to Q6) of the sub-scanning counter 819, and the gate 821. The enable signal Line3 of the add-on line 3 is generated.

On the other hand, as will be described in detail later, the main scanning counter 814 is loaded with an initial value by HSYNC,
The gates 815 to 817 input the upper 4 bits (Q3 to Q6) of the main scanning counter 814. AND gate 81
The output of 5 is H in the interval of 8 pixels for every 128 pixels,
This is the dot enable signal. Also, gate 8
16 and 817 input signals Line0 and Line3, respectively, in addition to the upper 4 bits of the main scanning counter 814, and generate mark enable signals for line 0 and line 3, respectively. These dot and mark enable signals are combined by an OR gate 818, and further,
The output of the OR gate 818 and the output of the AND gate 820 are logically ANDed by the AND gate 824, and become the dot and mark enable signal which becomes H only on the add-on line.

The output of the AND gate 824 is the F / F 82.
8, synchronized with the pixel synchronization signal CLK, AN
The D gate 830 is logically ANDed with the 2-bit output color selection signal CNO. Bit 0 of the output color selection signal CNO is negated by the inverter 829 and input to the AND gate 830, and bit 1 of the output color selection signal CNO is input to the AND gate 830 as it is. Therefore, the signal CNO = “10”, That is, the dot and mark enable signals become valid when the Y color image is printed.

Further, the output of the AND gate 824 is also connected to the clear terminal CLR of the counter 825, and the counter 825 outputs the pixel synchronizing signal only when the AND gate 824 is H, that is, when the add-on dot is enabled. CLK is counted, and bit 1 and bit 2 of the output of the counter 825 are input to the Ex-NOR gate 826, and the output of the Ex-NOR gate 826 is 4CLK in the middle of the add-on dot period (8CLK). It becomes L. The output of the Ex-NOR gate 826 is F / F.
The signal M is synchronized with the pixel synchronization signal CLK by 827.
It is output as INUS. When the signal MINUS is L, the add-on dots are modulated to + α.

The F / F 827 is for removing the whiskers of the signal MINUS and for matching the phase with the add-on dot enable signal.

The signal MINUS is input to the selection terminal S of the selector 838 in FIG.

In FIG. 11, the AND section 832 receives the 8-bit modulation amount α and the output of the AND gate 830 from the register 831. Since the output of the AND gate 830 becomes H at the timing of the add-on dots, the AND section 832 outputs the modulation amount α at the timing of the add-on dots. Therefore, the pixels other than the add-on dots are not modulated because the modulation amount output from the AND circuit 832 is 0.

The adder 833 and the subtractor 835 are both
An 8-bit image signal V, for example, is input to the terminal A. With respect to the modulation amount α output from the AND section 832 to the terminal B, the output of the adding section 833 is input to the OR circuit 834, and the output of the subtracting section 835 is input to the AND circuit 837.

The OR circuit 834 is the addition circuit 833.
Result V + α overflows and carry signal CY
Is output, the calculation result is forcibly set to 255, for example.
To Further, when the subtraction result V−α of the subtraction circuit 835 underflows and the carry signal CY is output, the AND circuit 837 forcibly outputs the operation result by, for example, 0 by the carry signal CY inverted by the inverter 836. It is something to do.

Both calculation results V + α and V−α are stored in the selector 8
38 is input to the selector 8 according to the signal MINUS.
It is output from 38.

With the above circuit configuration, the dot modulation shown in FIG. 5 is performed.

The value to be loaded into the main scanning counter 814 is generated as follows.

That is, in FIG. 12, first, the F / F 813 and the counter 80 are set by the sub-scanning synchronization signal VSYNC.
9 will be reset, so in the first add-on,
The initial value of the main scanning counter 814 is set to 0.

Here, the signal ADLIN input to the clock terminals of the counter 809 and the F / F 813 synchronizes the output of the AND gate 820 which is an add-on enable signal with the F / F 823 in synchronization with the main scanning synchronization signal HSYNC. It is a signal.

The selector 810 selects one of the registers 801 to 808 in which, for example, a 4-bit value of each of the eight add-on lines is set according to, for example, a 3-bit signal input to the select terminal S. Then, the value set in the selected register is output.

The select signal of the selector 810 is the signal A
It is generated by a counter 809 that counts DLIN. At the first add-on timing, the counter 809 is cleared by the sub-scanning synchronization signal VSYNC, so the select signal is 0. Therefore, the selector 810 selects the register 801. And signal A
When DLIN rises, the count value of the counter 809 advances by 1, and the selector 810 selects the register 802. After that, the selector 810 sequentially repeats the selection of the registers 803 to 808 in synchronization with the signal ADLIN.

The output of the selector 810 is the adder 811.
Then, it is added to the output of the adder 812, input to the F / F 813, latched at the falling edge of the signal ADLIN, and input to the main scanning counter 814.

The output of the F / F 813 is sent to the main scanning counter 814 and the terminal B of the adder 812 is also supplied.
Is also input to the adder 812 and is added to a constant value, for example, 8 input to the terminal A of the adder 812 and sent to the adder 811.
This is an offset value for making a gap between the dot position of the add-on line and the dot position of the add-on line one line before in the sub-scanning direction.

Copying Result FIG. 13 is a diagram showing an example of the copying result according to the present embodiment, but shows only an example of the arrangement of the unit dots of the add-on line.

In FIG. 13, reference numeral 901 is, for example, a specific original image. Also, the unit dot of add-on line is represented by a black square mark.

As described above, according to this embodiment,
By expressing the serial number peculiar to the copying machine, or the encoded serial number or the encoded serial number as an additional pattern,
If this embodiment is used for illegal copying such as forgery of securities, the copying machine used for illegal copying can be specified by examining the illegal copy.

Furthermore, when a pattern is added to the output image, complementary image signal modulation is combined in a small area to save the density as a whole, thereby eliminating the change in tint and reducing image quality deterioration. .

Example 2 In Example 1, an image including a specific pattern was formed in the final stage of image formation. However, when the intermediate transfer member 5 was used, this specific pattern was formed after forming a four-color image. The fifth image formation for forming only the image may be performed.

In this case, as in the first embodiment, it is difficult to use when subtracting from the image signal because the additional information preserves the image density, but in the case of adding by addition, a separate pattern adding circuit is required. Since only the reference pattern is generated without needing and only this is output, the configuration of the image scanner can be further simplified.

In addition, the complementary image signal modulation has an advantage that the additional pattern can be easily found and the additional information can be decoded more surely in a microscopic view.

As described above, according to this embodiment, the image forming means can be optimized in consideration of the additional pattern.

In the embodiment described above, the developing device is the developing device 3Y corresponding to the four kinds of color toners (yellow, cyan, magenta, black) necessary for forming a full-color image around the photosensitive drum 4. Although it has been described as a side-by-side developing device in which 3M, 3C, and 3Bk are fixedly installed, as another method, four developing devices are arranged around one rotation supporting shaft at an angle of 90 °. It is also possible to provide a rotary developing device which is rotatable about its axis and is sequentially rotated as needed to develop the latent image formed on the photosensitive drum 4. It is also possible to use a movable developing device in which four types of developing devices are arranged horizontally or vertically and which moves in the horizontal or vertical direction as required.

Further, regarding the method of forming a color image by superposing images, as described in the above embodiment,
In addition to the method in which the toner images of the respective colors are superposed on the intermediate transfer member 5 and then transferred to the recording material 6 all at once, the recording material 6 is carried on a transfer drum and each color is recorded on the recording material 6. It is also possible to transfer color images in a superimposed manner.

Furthermore, four image forming sections are provided, a photosensitive drum and a developing device are provided for each image forming section, and a recording material is sequentially moved in each image forming section, and color images of respective colors are transferred in an overlapping manner. The principle of the present invention can be applied to a so-called four-photoreceptor type image forming apparatus.

[0089]

As described above, the image forming apparatus according to the present invention performs image formation a plurality of times and forms a color image by superposing color images formed of color materials of a plurality of colors. The apparatus is configured to have an addition unit that adds information (pattern) unique to the image forming apparatus to an image of a specific color, and the image formation of the specific color to which the pattern is added is performed in the final image formation. Therefore, the pattern can be accurately formed with high image quality on the recording material, which is the final color image bearing member, without being disturbed, which is effective in preventing counterfeiting of securities.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an image processing apparatus of an image forming apparatus of the present invention.

FIG. 2 is a configuration diagram of an embodiment of an image forming apparatus of the present invention.

FIG. 3 is a diagram showing an example of a pattern unique to the image forming apparatus.

FIG. 4 is a block diagram illustrating a configuration example of an image scanner.

FIG. 5 is a diagram illustrating an example of an additional pattern.

FIG. 6 is a diagram showing an example of an add-on line.

FIG. 7 is a diagram showing an example of an add-on line.

FIG. 8 is a diagram showing an example of a method of expressing information by add online.

FIG. 9 is a diagram showing an example of a method of expressing information by add online.

FIG. 10 is a block diagram showing a configuration example of a pattern adding circuit.

FIG. 11 is a block diagram showing a configuration example of a pattern adding circuit.

FIG. 12 is a block diagram showing a configuration example of a pattern adding circuit.

FIG. 13 is a diagram showing an example of a copy result by the image forming apparatus of the present invention.

[Explanation of symbols]

 3 developing device 4 image carrier (photosensitive drum) 5 intermediate transfer member 6 recording material 101 original

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location H04N 1/04 (72) Inventor Jun Koide 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Satoshi Fukushima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hisashi Fukushima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (2)

[Claims] 1. In an image forming apparatus for forming a color image by performing image formation a plurality of times and superposing color images formed of color materials of a plurality of colors, information specific to the image forming apparatus is added to a color image of a specific color. An image forming apparatus having an addition unit for adding the information, wherein an image of a specific color to which the information is added is formed at the final image formation. 2. A color image formed of a plurality of color materials is superposed on an intermediate transfer body mainly composed of a resin film, and the color image is transferred to a final recording material to form an additional image formation of the information. The image forming apparatus according to claim 1, which is performed later.