JP2004240237A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which makes copying prevention processing possible over an entire image to be outputted when a read original is recognized as a specific original and does not make first copying time substantially longer when the original is recognized as an ordinary original. <P>SOLUTION: The image forming apparatus is provided with: an image read part to input an image data by reading the image of an original; a plurality of image forming parts to successively form images corresponding to colors resolved into a plurality of colors on the basis of the read image data; and an image recognizing part to recognize whether the read image data represent a specified image pattern in parallel with image formation by at least one image forming means. The image formation start timing T8 of a last image forming part (3K) corresponding to a color for which the image forming is performed lastly is delayed from timing T6 in which the image recognizing part recognizes the specified image pattern lastly. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a color image forming apparatus using an electrophotographic process, and more particularly to an image forming apparatus having a function of preventing illegal copying of a specific document such as securities.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a color copying machine has been used as one of color image forming apparatuses using an electrophotographic process. In recent years, along with technological innovations in the technical fields related to color copying, such as digital technology, image processing technology, and image forming technology, the number of color copying machines that can output a copy faithful to a manuscript has been increasing. For example, the risk of illegal copying using a color copying machine, especially a recent digital color copying machine, is increasing.
[0003]
For this reason, some digital color copiers have a function that does not perform copying when a specific document such as a bill or a security document is recognized when reading the document. There are also those that paint a copy with a color or superimpose a special mark.
[0004]
In the case of a digital color copier, a document is separated into three primary colors of red (R), green (G), and blue (B), read by a scanner as image data composed of a minimum unit of one dot, and 2. Description of the Related Art Conventionally, a method of storing data in a page memory or the like, and comparing it with a pattern of a specific document and recognizing the pattern is performed.
[0005]
FIG. 4 is a schematic timing chart showing a specific document recognition and image forming process according to a conventional method. Almost at the same time as the user starts copying at the timing P1, the scanner device starts reading an image and storing the image in the memory. At the timing P2, at the same time when the reading of the image and the storage in the memory are completed, the recognition is performed while comparing the read image stored in the memory with the pattern of the specific document. At timing P3, the comparison with the specific document ends. When the specific document is recognized, image processing such as changing data of the image data temporarily stored in the memory is performed at timing P4. If the specific document is not recognized at the timing P3, the read image is processed as it is, and the process proceeds to the process next to the timing P5.
[0006]
An image is formed by separating a changed image or a read image into yellow (Y), magenta (M), cyan (C), and black (K) colors. Since the order of these colors differs depending on the image forming apparatus, the expression of the first to fourth colors is used here. The image formation of the first color is performed at the timing P5, and the image formation of the second color is performed at the timing P6, the third color is formed at the timing P7, and the fourth color is formed at the timing P8. I do.
[0007]
The method according to Patent Literature 1 compares the size of a read original with the size of a registered specific original, and compares the color spectrum distribution of the original read in memory with the color spectrum distribution of the specific original, based on the above method. A method of recognizing by comparing with is also described. However, when the document is recognized as a specific document, unlike the above example, a signal for prohibiting image output is output instead of changing the read image so that the image forming unit does not operate.
[0008]
In the method described above, it is necessary to read all the images into the memory once, and a new memory and a new time for reading the images into the memory are required. On the other hand, in the method disclosed in Japanese Patent Application Laid-Open No. H11-163, while reading a document, comparison with a specific document and image forming processing are sequentially performed almost in parallel. From the point of time when it is determined that the image data matches the specific document, the pixel data of the area where the image has not been processed is replaced with 0. However, for example, only when most of the read specific document area has an image formed and the process of replacing pixel data with 0 determines that the copy prevention operation is insufficient, the remaining image is filled or a special mark Is performed. In this manner, the time required for image formation is reduced, and when a specific document is recognized, toner is not wasted.
[0009]
[Patent Document 1]
Japanese Patent No. 2904492 [Patent Document 2]
JP-A-11-215365
[Problems to be solved by the invention]
According to the conventional technique and the method disclosed in Japanese Patent Application Laid-Open No. H11-163, once the entire document is read, it is determined whether or not the document matches the size or the color spectrum distribution of the specific document, or comparison and collation are performed. When they match, there is an advantage that copy prevention processing can be performed reliably over the entire image. On the other hand, even in the case of a normal document, since the processing related to image formation starts after the determination is completed, the first copy time from when the user presses the copy start button to when the first copy is discharged is long. Problem. The first copy time is also one of the main factors that determine the performance of the copying machine.
[0011]
In the method disclosed in Japanese Patent Application Laid-Open No. H11-163873, since the reading of the original, the comparison with the pattern of the specific original, and the image formation are performed almost in parallel, the first copy time becomes longer as in the conventional technique and the method disclosed in Japanese Patent Application Laid-Open No. H11-157131. Not at all. However, in the case where the document matches the specific document, the image to be read after the matching point is subjected to the copy protection process. Therefore, compared with the method disclosed in Patent Document 1, the copy prevention process is performed, but the process is partially performed. Therefore, there is no guarantee that it will be effective.
[0012]
The present invention has been made in view of such circumstances, and when a read original is recognized as a specific original, it enables copy prevention processing over the entire output image, and when the read original is recognized as a normal original. It is another object of the present invention to provide an image forming apparatus in which the first copy time does not substantially increase.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, an image reading unit that reads an image of a document and inputs image data, and sequentially forms an image corresponding to colors separated into a plurality of colors based on the image data An image forming apparatus comprising: a plurality of image forming units; and an image recognizing unit that recognizes whether image data is a specific image pattern in parallel with image formation by at least one of the image forming units. Among the corresponding image forming units, the image forming start timing of the last image forming unit corresponding to the color for which an image is to be formed last is later than the timing at which the image recognition unit recognizes the specific image pattern at the latest.
[0014]
Further, by displacing the position of the final image forming unit to the downstream side of the sheet conveyance, the image forming start timing of the final image forming unit is set to be shorter than the timing at which the image recognizing unit recognizes the specific image pattern at the latest. Also slow down.
[0015]
Furthermore, when the image recognizing unit recognizes a specific image pattern, the final image forming unit forms an abnormal image over the entire area related to image formation based on the image data.
[0016]
The formation of the abnormal image is performed without operating any of the exposure unit, the charging unit, the transfer unit, and the development unit of the final image forming unit.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to FIGS. FIG. 1 is a diagram showing a schematic configuration of a digital color copying machine (hereinafter, a copying machine) which is an example of an image forming apparatus according to the present invention.
[0018]
In FIG. 1, a copying machine 1 is a so-called tandem-type copying machine in which independent image forming units are arranged in series for respective colors. The cyan (C) and black (K) image forming units 3Y, 3M, 3C, and 3K, the toner supply containers 4Y, 4M, 4C, and 4K corresponding to these colors, and the sheet P as a recording medium are stored. A paper feed cassette 5, a paper feed guide 6, a paper feed timing roller 7, a paper feed timing motor 7a for driving the paper feed timing roller 7, a transport belt 8, and a transport belt roller 11 for driving the transport belt. A transfer roller 12 for transferring the toner image formed by the image forming units 3Y to 3K onto a sheet, a fixing unit 13 for fixing the toner image to the sheet, a sheet discharging and conveying unit 14, and a sheet that has been copied is sequentially discharged. Paper laminated That the discharge unit 19, a control unit 20 for controlling the entire copying machine 1, and a operation unit 27 having an input unit and a display unit (not shown).
[0019]
The image forming units 3Y, 3M, 3C, and 3K for the respective colors include a developing unit 22, a photoconductor 23, a charger 24, an exposure device 25, a cleaning unit 26, and the like.
[0020]
2A and 2B schematically show the arrangement intervals of the image forming units 3Y to 3K shown in FIG. 1, wherein FIG. 2A shows the arrangement of the image forming units of a conventional copying machine, and FIG. 1 shows an arrangement of an image forming unit of the copying machine according to the first embodiment. In a conventional copier, as shown in FIG. 1A, the image forming units 3Y to 3K are disposed at substantially equal intervals at a distance L1 in the sheet conveyance direction. On the other hand, in the present embodiment, as shown in FIG. 2B, the image forming units 3Y to 3C are arranged at substantially equal intervals at a distance L1 in the sheet conveyance direction. The interval between the forming parts 3C and 3K is the distance L2. In this case, the arrangement is such that the relationship of L2> L1 is clearly established. The specific relationship between the intervals L1 and L2 will be described later.
[0021]
Next, a schematic operation of the copying machine 1 having the above configuration will be described with reference to FIGS. FIG. 3 is a timing chart showing a process of recognizing a specific document and forming an image according to the embodiment. First, after a document is set on the image reading unit 2, the operation unit 27 is operated to start copying at timing T1. At timing T2, the image signal of the document read and scanned by the image reading unit 2 is slightly delayed at timing T2. An image recognizing unit (not shown) provided in the control unit 20 sequentially starts comparison with the data of the specific document for each data unit such as a line or a byte.
[0022]
At the same time, the read red (R), green (G), and blue (B) data are color-separated into yellow, magenta, cyan, and black for each data unit by the control unit 20, and subjected to various image processing. Therefore, at timing T2, the first color, that is, in this example, the photoconductor 23 charged by the charger 24 of the image forming unit 3Y is exposed by the exposure device 25 in accordance with the yellow image signal, and the surface thereof is charged with an electrostatic latent image. An image is formed and developed by the developing device 22 to form a yellow visible image on the surface of the photoconductor 23. Such an image forming process is performed for each color.
[0023]
On the other hand, the paper P fed from the paper feed cassette 5 is guided and sent out by the paper feed guide 6, but temporarily stops while the leading end of the paper P is sandwiched by the paper feed timing roller 7. When the paper feed timing motor 7a is driven by a signal from the control unit 20 in synchronization with the image formation on the photosensitive member 23, the paper feed timing roller 7 rotates the paper P counterclockwise. To the upper surface of the conveyor belt 8. Then, the sheet P is attracted to the upper surface of the transport belt 8, and first, when passing immediately below the image forming unit 3 </ b> Y, a yellow image is transferred onto the sheet P by the transfer roller 12 to which a transfer voltage is applied.
[0024]
Next, the image formation by the image forming unit 3M is started at a timing T3 according to the same process as that of the image forming unit 3Y at a timing T3 with the distance between the image forming units 3Y and 3M being delayed by the time that the sheet P advances. The paper P on which the yellow image has been transferred is conveyed directly below the image forming unit 3M, and the transfer of the magenta image is started. Similarly, the image formation by the image forming unit 3C is started at a timing T4 with a delay of the distance between the image forming units 3M and 3C by the time the sheet P advances, and the transfer of the cyan image to the sheet P is further started.
[0025]
Thereafter, the image reading of the document ends at timing T5, and the comparison with the specific document ends at timing T6, which is slightly delayed. At this time, if it is determined that the image matches the specific document, the black (fourth color) image formation has not yet started in the present embodiment, and the processing method to be performed is determined at timing T7. When digital image processing is not required in the processing method according to the present embodiment, which will be described later, the timing T7 for determining the processing method is a time that is negligibly short. The specific image copy prevention process is performed by the black image forming unit 3K, but after this timing, the image forming unit 3K is configured to abnormally read and partially or completely form the image formed by the image forming units 3Y to 3C. 3K can be controlled by the control unit 20. If it is determined at timing T7 that the document does not match the specific document and is determined to be a normal document, the fourth color image is formed based on a normal process.
[0026]
In this way, if it is determined at T7 that processing to make an image formed so far abnormal or normal image formation is performed, black image formation is started at timing T8, and the paper P Then, a black image is further transferred. Thereafter, the sheet P is subjected to a fixing process in the fixing unit 13, conveyed by the sheet discharging and conveying unit 14, and discharged to the sheet discharging unit 19.
[0027]
In the present embodiment, the read image data is not temporarily stored in the page memory or the like, and image processing and image recognition for comparison with a specific document are performed for each data unit almost in parallel with the reading. If it is determined in T7 that the image data matches the specific document, it is difficult to change the image data by digital image processing and form an image in the image forming unit 3K because the image data so far is not sufficiently stored. is there. Therefore, the control unit 20 controls the exposure device 25 of the image forming unit 3K to perform full exposure, no exposure, or intermittent exposure from the start to the end of image formation. Alternatively, the charging unit 24 of the image forming unit 3K is controlled to be uncharged from the start to the end of image formation or to be intermittently charged. Alternatively, the transfer of the transfer voltage from the image forming unit 3K to the sheet P is performed normally by stopping the application of the transfer voltage to the transfer roller 12 immediately below the image forming unit 3K and performing non-transfer, or performing intermittent transfer. It may not be done. Of course, it is also possible to control the application of the developing bias to the developing roller (not shown) of the developing unit 22 of the image forming unit 3K to stop, to discontinue the application, or to make the bias voltage abnormal.
[0028]
As described above, the image forming unit 3 </ b> K may not be able to form a normal image or may not be normally transferred to the paper P. If a specific mark or the like is superimposed with the fourth color, control may be performed. It is also possible to generate desired mark data by a pattern generator (not shown) of the unit 20 and operate the exposure device 25 of the image forming unit 3K with the data. In this embodiment, the image forming units 3 are arranged in the order of yellow, magenta, cyan, and black. However, the image forming units 3 are arranged so that the colors other than black become the fourth color, and it is recognized that they match the specific document. In this case, it is possible to prevent a normal color image from being formed.
[0029]
As described above, the comparison with the specific document is completed at the timing T6, the control of the image formation of the fourth color can be determined at the timing T7, and the control can be performed at the time of the image formation of the fourth color at the timing T8. As described above, as described above, the image forming unit for the fourth color is arranged so that the condition of L2> L1 is satisfied as shown in FIG. 2B. That is, the time t1 shown by the timing in FIG. 3 corresponds to the distance L1, and the time t2 corresponds to the distance L2. The time lag between the image formation start time of the image forming unit 3Y and the image forming unit 3M and the time lag between the image formation start time of the image forming unit 3M and the image forming unit 3C is time t1, respectively, and the image forming unit 3C and the image forming unit 3K. Is a time t2.
[0030]
That is, if the arrangement position of the image forming unit 3K is determined so that the image forming start timing of the image forming unit 3K is later than the timing T6 at which the comparison with the specific document ends, the entire area of the image of the fourth color is determined. It is possible to reliably perform the copy prevention process over the entire period. When the time t2 is thus determined, the distance L2 can be determined by multiplying the time t2 by the process speed of the copying machine 1 (for example, the peripheral speed of the photoconductor).
[0031]
Further, since the comparison with the specific document is started from the timing T2, it may be recognized that the document matches the specific document before the comparison of all the image areas is completely completed. In this case, the timings T6 and T7 in FIG. 3 may move to the left in the drawing and occur early. Even in such a case, the image forming unit 3K has not started the image formation, and it is a time when the image forming unit 3K can sufficiently perform the copy prevention processing. Further, if necessary, in addition to the copy prevention process for the fourth color, the copy prevention process may be performed by the above-described method on the remaining image forming areas of the image forming units 3Y to 3C where the image formation has not been completed. By controlling, it is possible to more reliably prevent the copying of the specific document.
[0032]
Further, the color image forming apparatus described in the present embodiment is a tandem type including a plurality of image forming units that form images independently for each color. There is also a method in which an image of one color is formed and transferred to an intermediate transfer body, and for other colors, this process is repeated, and a plurality of color images are superimposed on the intermediate transfer body and then transferred to paper. . In the case of such a method, the developing device is arranged at a position where the development start timing of the developing device of the color that performs image formation last is later than the timing at which the determination that matches the specific document is performed latest. The present invention can be applied. In this case, a similar effect can be obtained by controlling the developing bias or another object that can be controlled in timing.
[0033]
In the present embodiment, a copying machine that forms a color image using four colors has been described as an example. However, the color copying machine that can implement the present invention is not limited to four colors. For example, three or five colors can be used. Even in the case described above, it becomes possible by arranging the positions of the image forming unit and the developing device for performing image formation lastly at the above-mentioned timing.
[0034]
【The invention's effect】
According to the present invention, in a copying machine that superimposes a plurality of colors, synthesizes colors, and copies a document, an image forming unit or a developing device that forms an image of the last color requires a copy prevention process for the entire image forming area. By arranging them at timings where they can be performed, when a specific document such as a bill or securities is recognized, it is possible to perform a reliable copy prevention process on the entire area of image formation. Further, since such a reliable copy prevention process can be performed without specially providing a memory for storing image data of the entire area of image formation, an inexpensive copying machine having a simple configuration can be realized. .
[0035]
Further, according to the present invention, in addition to the above features, by performing comparison with a specific document and image processing in parallel while reading the document, it is possible to achieve an excellent effect that the first copy time does not substantially increase. Become.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a digital color copying machine as an example of an image forming apparatus according to the present invention.
FIGS. 2A and 2B schematically show arrangement intervals of image forming units 3Y to 3K shown in FIG. 1, wherein FIG. 2A shows an arrangement of image forming units of a conventional copying machine, and FIG. 1 shows an arrangement of an image forming unit of the copying machine according to the first embodiment.
FIG. 3 is a timing chart illustrating a process of recognizing a specific document and forming an image according to the embodiment;
FIG. 4 is a schematic timing chart showing a specific document recognition and image forming process according to a conventional method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Copier 2 Image reading part 3Y, 3M, 3C, 3K Image forming part 4Y, 4M, 4C, 4K Toner supply container 5 Paper supply cassette 6 Paper supply guide 7 Paper supply timing roller 7a Paper supply timing motor 8 Transport belt 11 Transport Belt roller 12 Transfer roller 13 Fixing unit 14 Discharge transport unit 19 Discharge unit 20 Control unit 22 Developing unit 23 Photoconductor 24 Charger 25 Exposure device 26 Cleaning unit 27 Operation unit P1 to P10 Timing T1 to T8 Timing t1, t2 Time

Claims (4)

An image reading unit that reads an image of a document and inputs image data, a plurality of image forming units that sequentially form images corresponding to colors separated into a plurality of colors based on the image data, and at least one image forming unit An image recognition unit that recognizes whether the image data is a specific image pattern in parallel with the image formation by the unit.
The image recognizing unit recognizes the specific image pattern at the latest in the image forming start timing of the final image forming unit corresponding to the color to be imaged last among the image forming units corresponding to the plurality of colors. An image forming apparatus characterized in that the timing is later than the timing. By arranging the position of the final image forming unit so as to be shifted to the downstream side of the sheet transport, the image forming start timing of the final image forming unit is determined by the timing at which the image recognition unit recognizes the specific image pattern latest. The image forming apparatus according to claim 1, wherein the image forming apparatus is slowed down. The said final image forming part performs formation of an abnormal image over the whole area | region which concerns on image formation based on the said image data, when the said image recognition part recognizes the said specific image pattern, The Claims 1 or 2 characterized by the above-mentioned. The image forming apparatus according to claim 2. The image forming apparatus according to claim 3, wherein the abnormal image is formed without operating any of the exposing unit, the charging unit, the transfer unit, and the developing unit of the final image forming unit.

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