JP4059195B2 - Image forming apparatus and printing method - Google Patents

Description

  The present invention relates to a copying machine, a printer, a facsimile, or a complex machine (hereinafter referred to as an image forming apparatus) that performs printing, and a printing method that prints a pattern image for confirming whether a printed material is an original.

  Conventionally, various technologies have been developed to prevent forgery of printed matter. For example, a method has been proposed in which a character image such as “copy” is printed as a latent image on a background image (see, for example, Patent Document 1). In this method, when the original is printed, the latent image such as a character or a pattern to be latent image has a relatively large dot (halftone dot with a small number of lines) and a high dot density, and the background image is relatively small. By controlling the dot size and dot density so that the dot density is small at the dots (dots with high number of lines) and the apparent density and color of the latent image and the background image are the same. Thus, it is possible to obtain a printed material in which the latent image and the background image are apparently the same, that is, the latent image is merged with the background.

  However, when attempting to copy a printed material on which such a latent image and a background image are printed, the background image has a high resolution and cannot be read by the copying machine. Only the latent image having a low resolution is read and printed. A copy is obtained. As a result, it is possible to distinguish between the original and the duplicate and to obtain the effect of suppressing unauthorized copying.

In addition, when creating a set of two printed materials, a pattern image obtained by randomly dividing the stamp image into two parts is created and divided so that it can be confirmed later that these printed materials are a pair. A method for printing a pattern image on each surface of a set of two printed materials has also been proposed (see, for example, Patent Document 2). At the time of confirmation, the pattern images printed on the respective printed materials can be superposed and seen through the watermark, and if the seal image is reproduced, it can be confirmed as the original.
JP 2001-197297 A JP 2001-71579 A

  However, in the method described in Patent Document 1, since the latent image is reproduced only when the original printed material is copied, it is impossible to determine whether the printed material is the original or the duplicate without copying. Further, in the method described in Patent Document 2, since the pattern image divided into two must be printed on different printed materials, it cannot be applied unless there are two printed materials. Furthermore, when a watermark is viewed through a pattern image obtained by dividing the seal image into two parts, if the viewer aligns the pattern images so that they match each other, the seal image can be reproduced. However, it is impossible to determine whether the printed material is a genuine copy or a duplicate copy, and it is possible to copy for illegal purposes.

  An object of the present invention is to make it possible to easily determine whether a printed material is an original or a duplicate, and to suppress forgery of the printed material.

According to a first aspect of the present invention, in the image forming apparatus,
A first pattern image and a second pattern image in which a specific image is visualized when superimposed, and the first pattern image and the second pattern image created according to the type of the recording medium are stored A pattern storage unit to
The first pattern image and the second pattern image corresponding to the type of the recording medium designated at the time of printing are acquired from the pattern storage unit, and one of the acquired first pattern image or second pattern image is recorded on the recording medium Printing on one side of the recording medium, and printing the other of the acquired first pattern image or second pattern image on the other side of the recording medium at a position overlapping the one pattern image via the recording medium And
It is characterized by providing.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect,
The first pattern image and the second pattern image include the reflection density of the first pattern image printed on one surface via the recording medium and the transmission of the second pattern image printed on the other surface. It is characterized in that it is created so that the density substantially matches the density.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect,
The first pattern image and the second pattern image are pattern images created by synthesizing randomly generated random pattern images and specific images.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects,
The first pattern image and the second pattern image are pattern images created in units of dots,
The printing unit prints the first pattern image and the second pattern image in dot units.

According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects,
At the time of printing, comprising a control unit for creating composite data obtained by combining the print data to be printed with the first pattern image and the second pattern image,
The printing unit prints the print data on a recording medium based on the created composite data, and prints either the first pattern image or the second pattern image on one surface via the recording medium. Printing is performed, and the other of the first pattern image and the second pattern image is printed on the other surface of the recording medium.

The invention described in claim 6
A printing method for printing on a recording medium a first pattern image and a second pattern image in which a specific image is visualized when superimposed,
Of the first pattern image and the second pattern image created according to the type of the recording medium, one of the first pattern image and the second pattern image according to the type of the recording medium designated at the time of printing On one side of the recording medium,
The other of the first pattern image or the second pattern image is printed on the other surface of the recording medium at a position overlapping with the one pattern image via the recording medium.

The invention according to claim 7 is the printing method according to claim 6 ,
At the time of printing, create composite data by combining the print data to be printed with the first pattern image and the second pattern image,
Based on the created composite data, print data is printed on a recording medium, and either the first pattern image or the second pattern image is printed on one surface via the recording medium, and the recording medium The other of the first pattern image and the second pattern image is printed on the other side of the image.

According to the invention of claim 1, 6, the first pattern image and the second pattern image, since the printed to overlap each other via the recording medium, viewed watermark print original from one surface When a particular image is visualized. Since reading accuracy is generally inferior to output accuracy, a similar pattern image cannot be reproduced when copying the original. Therefore, the specific image cannot be visualized when the copy is viewed through. Therefore, it is possible to easily determine whether the printed material is the original or the duplicate by viewing the printed material through the watermark.
Further, since the first pattern image and the second pattern image corresponding to the type of recording medium designated for printing are printed at the time of printing, each pattern image can be printed at an optimum density corresponding to the recording medium. Therefore, the reproducibility of the specific image visualized by each pattern image is good.

  According to the second aspect of the present invention, the first pattern image and the second pattern image include the reflection density when the first pattern image is printed for each paper type of the printing paper, and the second pattern. Since the density adjustment is made so that the transmission densities when the image is printed are substantially the same, the reproducibility of the specific image visualized by each pattern image is good.

  According to the third aspect of the present invention, the first pattern image and the second pattern image can be created from the random pattern image.

  According to the fourth aspect of the present invention, since the first pattern image and the second pattern image are created in dot units and printed in dot units, it is difficult to reproduce each pattern image by copying the original printed material. Thus, counterfeiting of each pattern image can be prevented.

According to the inventions described in claims 5 and 7 , composite data obtained by combining the print data with the first pattern image and the second pattern image is created, and the print data and the first pattern image are generated based on the composite data. Since the second pattern image and the second pattern image are printed, each pattern image can be printed together with the print data.
Further, since the first pattern image and the second pattern image corresponding to the type of recording medium designated for printing are printed at the time of printing, each pattern image can be printed at an optimum density corresponding to the recording medium. Therefore, the reproducibility of the specific image visualized by each pattern image is good.

  In the present embodiment, the first pattern image and the second pattern image created according to the paper type of the printing paper are preliminarily stored in the image forming apparatus so that the specific image is visualized when viewed in a superimposed manner. The first pattern image is printed at a predetermined position on one side of the printing paper and printed on the other side of the printing paper at a position overlapping the first pattern image during printing. An example of printing the second pattern image will be described. In the following description, the first pattern image and the second pattern image are referred to as a watermark.

First, the configuration will be described.
FIG. 1 shows an internal configuration of an image forming apparatus 1 in the present embodiment.
As shown in FIG. 1, the image forming apparatus 1 includes a control unit 11, an operation unit 12, a display unit 13, an HDD (Hard Disk Drive) 14, a pattern storage unit 15, a communication unit 16, an image reading unit 17, and a print data memory. 18 and a printing unit 19.

The control unit 11 is a control unit that includes a CPU (Central Processing Unit) 11a, a RAM (Random Access Memory) 11b, and the like. The control unit 11 comprehensively controls print processing operations in cooperation with a print processing program stored in the HDD 14. For example, copy mode in response to an instruction from the operation unit 1 2, printer mode, switches the scanner mode, scaling the print data, and data processing such as rotation, control of the print processing by the printing unit 19, by the image reading section 17 Control image reading.

  Further, the control unit 11 reads out the watermark processing program according to the present invention from the HDD 14 and comprehensively controls the watermark processing in cooperation with the program.

  In the watermark processing, the first pattern image and the second pattern image corresponding to the paper type of the printing paper designated by the printing conditions are acquired from the pattern storage unit 15, and the first pattern image and the second pattern image are acquired. Composite data is created by combining an image and print data to be printed. The composite data is created so that the first pattern image and the print data are placed on the front surface of one print sheet, and the second pattern image is located on the back surface of the print pattern so as to overlap the first pattern image via the print sheet. Is done. Note that when double-sided printing is instructed, composite data is created so that the print data and the second pattern image are printed on the back side of the printing paper. Next, the composite data is output to the printing unit 19 and the printing operation is controlled.

  The operation unit 12 includes a key group such as various function keys and numeric keys for setting printing conditions such as the number of prints, paper type, double-sided / single-sided printing, and print magnification, and a touch panel configured integrally with the display unit 13. And an operation signal corresponding to the operation is output to the control unit 11.

  The display unit 13 is composed of an LCD (Liquid Crystal Display) or the like, and displays various messages such as a setting screen for setting printing conditions and a notification of a printing result in accordance with an instruction from the control unit 11.

  In addition to the print processing program, the HDD 14 stores a watermark processing program and data processed by each program.

  The HDD 14 also includes a tray setting table 141 for managing printing paper set in the tray of the printing unit 19. In the tray setting table 141, as shown in FIG. 2, for each tray, the paper type (for example, “plain paper” for tray 1) currently set in the tray and the paper size (for example, for tray 1) are set. "A4") information is stored.

The pattern storage unit 15 stores image data groups of the first pattern image and the second pattern image that realize the watermark.
FIG. 3 shows an example of a first pattern image, a second pattern image, and a watermark realized by these pattern images.
As shown in FIG. 3, the first pattern image 2a and the second pattern image 2b are images that are substantially square and in which black dots (halftone dots) are arranged in dot units. Each of the pattern images 2a and 2b looks like a meaningless image in which dots are randomly arranged when viewed independently, but in practice, the image 2 is superimposed on the pattern images 2a and 2b so as to coincide with each other. When it is obtained, it is created by setting dots so that a specific image (character image of “K” in the drawing) is visualized.

An example of a method for creating the first pattern image and the second pattern image will be described with reference to FIG.
As shown in FIG. 4, first, in STEP 1, a specific image m1 to be latent image (an example in which a character image of “K” in the figure is applied will be described. However, for example, “COPY”, “Handling Precautions”, etc. A character image, an image such as a logo mark, etc. can be applied (hereinafter referred to as a mask image), and a random pattern image m2 having a substantially square shape and randomly set with dots is prepared.

  Next, in STEP 2, the mask image m1 and the random pattern image m2 are overlaid, and a logical product (AND) and an exclusive logical sum (XOR) of the random pattern image and the mask image are calculated in the mask image region. In STEP 3, a pattern image m 3 is created in which an output value that is the result of the logical product is set in the mask image area. On the other hand, a pattern image m4 is created in which an output value that is the result of the exclusive OR operation is set in the mask image area.

  Next, the density adjustment of the pattern images m3 and m4 is performed. If the reflection density of the first pattern image and the transmission density of the second pattern image are significantly different when viewed through the printing paper from the surface on which the first pattern image is printed, the apparent density differs. This makes it difficult to visualize the mask image. Therefore, the dot density of each of the pattern images m3 and m4 is adjusted in order to adjust the apparent density. For example, the dots in the mask area of the pattern image m3 are deleted to reduce the dot density, and the dot density of the pattern image m4 is increased by adding dots at positions that match the dot positions deleted in the pattern image m3 in the pattern image m4. Increase.

  When the density adjustment is performed, the dot position of the pattern image m4 is reversed left and right. Here, the inversion of 180 degrees to the left and right is performed because the first pattern image is printed on the front side of the printing paper and the second pattern image is printed on the back side.

  Thus, the first pattern image 2a and the second pattern image 2b can be finally obtained. The first pattern image 2a and the second pattern image 2b are images in which dots are randomly arranged in appearance, but the first pattern image 2a and the second pattern image 2b are made to coincide with each other. When superimposed, the mask image is visualized as shown in FIG.

The reflection density of the first pattern image and the transmission density of the second pattern image differ depending on the paper quality of the printing paper on which the pattern image is printed. If the printing paper is thick or the like, the transmission density of the second pattern image is lowered, so that the reproducibility of the watermark is lowered and density adjustment is required. Therefore, the first pattern image and the second pattern image are created for each paper type according to the paper type of the printing paper.
Note that the pattern image generation method described above is an example, and the present invention is not limited to this.

The pattern storage unit 15 includes a pattern table 151 for managing the stored pattern image.
As shown in FIG. 5, the pattern table 151 stores the image file names of the first pattern image and the second pattern image created according to the type of printing paper for each type of watermark. For example, when printing the watermark 1, if the paper type is “plain paper”, the first pattern image “pattern A1” created according to the quality of the plain paper and the second pattern image “pattern A2” are created. "Is used for watermark printing.

  The communication unit 16 includes a communication interface such as a network interface and a modem, and exchanges information with external devices on the communication network. For example, print target data is received from a user terminal connected via a communication network.

  The image reading unit 17 includes a light source, a photoelectric conversion device such as a CCD (Charge Coupled Device), and the like below the contact glass. The image reading unit 17 optically scans a document placed on the contact glass, and reflects the reflected light. After photoelectric conversion by the CCD, the original image data is obtained by digital conversion. The acquired image data is stored in the print data memory 18 as print data. An automatic document feeder (hereinafter referred to as ADF; Auto Document Feeder) may be provided to read a document image.

  The print data memory 18 is a memory for storing print data to be output, such as image data read by the image reading unit 17 and print data received via the communication unit 16.

  The printing unit 19 includes a plurality of trays that store printing paper of each paper type, and performs ink jet printing. The printing unit 19 feeds printing paper from the tray specified by the control unit 11 and receives a print instruction. Printing is performed on printing paper based on the print data. Note that the printing method of the printing unit 19 may be an electrophotographic method or any other printing method as long as it can print dot data of image data halftone by screen processing.

Next, the operation in the present embodiment will be described.
FIG. 6 is a flowchart for explaining watermark processing executed when the image forming apparatus 1 prints a watermark together with print data.
In the watermark process shown in FIG. 6, a setting screen for setting printing conditions is first displayed on the display unit 13, and in accordance with an instruction from the user input via the operation unit 12, the number of copies, single-sided / double-sided printing, Printing conditions such as printing density, printing paper tray selection, and watermark printing are set (step S1).

  When a printing instruction is input after setting the printing conditions (step S2; Y), it is determined whether or not watermark printing is set as the printing conditions (step S3). If watermark printing is not set (step S3; N), the print data designated for printing is read from the print data memory 18, and normal printing processing is performed under the set printing conditions (step S3). S4) This process is terminated.

  On the other hand, when the printing of the watermark is instructed (step S3; Y), the paper type of the printing paper set in the tray designated as the printing condition is determined based on the tray setting table 141 (step S3). ), The first pattern image and the second pattern image corresponding to the determined paper type and the type of watermark designated for printing are acquired from the pattern storage unit 15 (step S4).

  Next, in the control unit 11, print data designated for printing is read from the print data memory 18, and composite data is generated by combining the print data with the acquired first pattern image and second pattern image. And output to the printing unit 19. In the printing unit 19, printing paper designated for printing is fed from the tray, and based on the composite data input from the control unit 11, the printing data is printed on the surface of the printing paper and at a predetermined position on the surface. A first pattern image is printed (step S5).

  When the printing on the front surface is completed, the printing paper is reversed in the printing unit 19, and the second pattern image is printed on the back surface of the printing paper at a position overlapping the first pattern image printed on the front surface (step S6). . At this time, if double-sided printing of print data is instructed, the print data is printed together with the second pattern image on the back surface of the printing paper. In addition, in order to print each pattern image at an accurate printing position, a printing paper on which a register mark for adjusting the printing position is printed in advance may be used.

FIG. 7 shows a print example of the first pattern image and the second pattern image.
FIG. 7A is a diagram illustrating an example in which the first pattern image 2a is printed on the front surface of the printing paper p, and FIG. 7B is a back surface of the printing paper p shown in FIG. 7A. It is a figure which shows the example by which the 2nd pattern image 2b was printed. The first pattern image 2a and the second pattern image b are printed at positions where the pattern images printed on the front and back sides coincide with each other when viewed through the printing paper. At the time of printing, the edge of the printing paper is detected. For example, the distances y1, y2 from the upper edge to the pattern images 2a, 2b are equal and the distances y1, y2 from the right edge to the pattern images 2a, 2b are detected. The printing is performed so as to be equal.

In this way, when the first pattern image and the second pattern image are printed together with the print data, this process is terminated.
The original printed matter on which the first pattern image and the second pattern image are printed as the watermark is viewed from the surface on which the first pattern image is printed, as shown in FIG. The first pattern image and the second pattern image overlap each other so that the mask image can be discriminated, and it can be confirmed that the printed material is the original.

  However, when a duplicate is created by copying the original printed material, the first pattern image and the second pattern image are high-resolution images printed in dot units. Therefore, the resolution of the pattern image printed by copying is lowered, and the original pattern image cannot be accurately reproduced. In addition, since it is almost impossible to accurately read the pattern image on the front and back so that the print position matches when reading the original image, the pattern image printed on the front and back of the printing paper by copying must always have the print position. It will shift. In other words, it is possible to confirm that the duplicate copy obtained from the original copy cannot be visualized from the pattern image printed on the front and back sides of the printing paper as shown in FIG. .

  As described above, according to the present embodiment, when printing the original, the first pattern image and the second pattern image created so that the specific image is visualized when superimposed are printed on the printing paper. Therefore, the specific image can be visualized when the original printed material is viewed through. Further, since the first pattern image and the second pattern image are created and printed in dot units, the same pattern image as the original cannot be reproduced when the original is copied. Therefore, the specific image cannot be visualized when the copy is viewed through. Therefore, it is possible to easily determine whether the printed material is the original or the duplicate by viewing the printed material through the watermark.

  In addition, the first pattern image and the second pattern image include a reflection density when the first pattern image is printed for each paper type and a transmission density when the second pattern image is printed. Since the first pattern image and the second pattern image corresponding to the paper type of the printing paper designated for printing are printed at the time of printing, the density is adjusted so as to be substantially the same. Each pattern image can be printed at a high density. Therefore, the reproducibility of the specific image visualized by each pattern image is improved.

  Note that the description in this embodiment is a preferred example of the image forming apparatus 1 to which the present invention is applied, and the present invention is not limited to this.

  For example, in the above description, the example in which the first pattern image and the second pattern image for realizing the watermark are created in advance and the image forming apparatus 1 is provided has been described. The image forming apparatus 1 may calculate and create the first pattern image and the second pattern image that realize the watermark using the character or image selected by the above as a mask image. Further, the first pattern image and the second pattern image created in the user terminal may be received together with the print data and printed.

  Further, the example in which the printing paper is applied as the recording medium has been described. However, the present invention is not limited to this, and any other recording medium such as a transparent OHP sheet can be used as long as the recording medium can see the other side through the other side. Is also applicable.

  In addition, the detailed configuration and detailed operation of the image forming apparatus 1 according to the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

1 is a diagram showing an internal configuration of an image forming apparatus 1 in the present embodiment. 5 is a diagram illustrating an example of a data configuration of a tray setting table 141. FIG. It is a figure which shows an example of the watermark implement | achieved by the 1st pattern image, the 2nd pattern image, and these pattern images. It is a figure which shows an example of the production method of a 1st pattern image and a 2nd pattern image. It is a figure which shows the data structural example of the pattern table 151. FIG. 4 is a flowchart for explaining watermark processing executed by the image forming apparatus 1. (A) is a figure which shows the example by which the 1st pattern image was printed on the surface of printing paper, (b) is the 2nd pattern on the back surface of the printing paper on which the 1st pattern image was printed. It is a figure which shows the example by which the image was printed. (A) is a figure which shows a mode that the mask image was visualized when the printed matter is the original, and (b) is a state that the mask image is not visualized and cannot be distinguished when the printed matter is a duplicate. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 11 Control part 11a CPU
11b RAM
12 Operation unit 13 Display unit 14 HDD
141 Tray setting table 15 Pattern storage unit 151 Pattern table 16 Communication unit 17 Image reading unit 18 Print data memory 19 Printing unit

Claims (7)

A first pattern image and a second pattern image in which a specific image is visualized when superimposed, and the first pattern image and the second pattern image created according to the type of the recording medium are stored A pattern storage unit to
The first pattern image and the second pattern image corresponding to the type of the recording medium designated at the time of printing are acquired from the pattern storage unit, and one of the acquired first pattern image or second pattern image is recorded on the recording medium Printing on one side of the recording medium, and printing the other of the acquired first pattern image or second pattern image on the other side of the recording medium at a position overlapping the one pattern image via the recording medium And
An image forming apparatus comprising:   The first pattern image and the second pattern image include the reflection density of the first pattern image printed on one surface via the recording medium and the transmission of the second pattern image printed on the other surface. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is formed so as to have a density that substantially matches the density.   The first pattern image and the second pattern image are pattern images created by combining a randomly generated random pattern image and a specific image, respectively. Image forming apparatus. The first pattern image and the second pattern image are pattern images created in units of dots,
The image forming apparatus according to claim 1, wherein the printing unit prints the first pattern image and the second pattern image in units of dots. At the time of printing, comprising a control unit for creating composite data obtained by combining the print data to be printed with the first pattern image and the second pattern image,
The printing unit prints the print data on a recording medium based on the created composite data, and prints either the first pattern image or the second pattern image on one surface via the recording medium. printed, the image forming apparatus according to any one of claim 1 to 4, characterized in that to print the other of the first pattern image or the second pattern image on the other surface of the recording medium. A printing method for printing on a recording medium a first pattern image and a second pattern image in which a specific image is visualized when superimposed,
Of the first pattern image and the second pattern image created according to the type of the recording medium, one of the first pattern image and the second pattern image according to the type of the recording medium designated at the time of printing On one side of the recording medium,
A printing method comprising printing the other of the first pattern image or the second pattern image on the other surface of the recording medium at a position overlapping with the one pattern image via the recording medium. At the time of printing, create composite data by combining the print data to be printed with the first pattern image and the second pattern image,
Based on the created composite data, print data is printed on a recording medium, and either the first pattern image or the second pattern image is printed on one surface via the recording medium, and the recording medium The printing method according to claim 6 , wherein the other of the first pattern image and the second pattern image is printed on the other surface of the printing apparatus.

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