JP2020160154A - Image forming apparatus and image structure - Google Patents

Abstract

To create a watermark image that, for an image created in a specified area on a surface of a medium, makes the shadow of the image seen through from the back side of the medium different from the shadow of the image seen from the front side.SOLUTION: An image forming apparatus comprises: selection means 1 that selects whether to create, on a surface of a medium S with transmission properties, a watermark image Gt that is visually recognized by seeing through from the back side of the medium S; specification means 2 that, when the selection means 1 selects to create the watermark image Gt, specifies an area and a mode for creating the watermark image Gt; similar color image forming means 3 that creates, for the area specified by the specification means 2, a watermark part Ga of the watermark image Gt by using an image forming agent in the similar color with the medium S, according to the mode specified by the specification means 2; and transparent image forming means 4 that creates, for the area specified by the specification means 2, a non-watermark part Gb of the watermark image Gt by using a transparent image forming agent, according to the mode specified by the specification means 2.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image forming apparatus and an image structure.

Conventionally, those described in Patent Documents 1 and 2 are already known as this type of image forming apparatus.
Patent Document 1 is an information forming sheet in which unique information is printed on the front surface of a paper base material and a watermark image is printed on a predetermined portion on the back surface, and one or both sides of the front surface and the back surface of the paper base material are printed. A tint block is formed on the entire surface or a predetermined portion of the paper, and watermark information is formed by a UV-curable printing ink in which a color pigment ink different from the paper color other than the paper color is mixed with white ink, and the watermark is transparent to light from the front side. A technique for visually recognizing the watermark information is disclosed.
In Patent Document 2, a visible watermark pattern stored in a memory is read, an invisible watermark is drawn on the read visible watermark pattern, and the image data in which both are mixed is multiplied by a superposition rate to obtain these visible / invisible watermarks. A technique of adding data to input image data to generate watermark superimposed image data is disclosed.

Japanese Patent No. 5615072 (Form for carrying out the invention, FIG. 1) Japanese Unexamined Patent Publication No. 2006-262486 (best form for carrying out the invention, FIG. 2)

The technical problem to be solved by the present invention is a watermark image that makes the shadow of the image seen through the back side of the medium different from the shadow of the image seen from the front side with respect to the image created in the designated area on the surface of the medium. To be.

The invention according to claim 1 is a selection means for selecting whether or not to produce a watermark image that can be visually recognized through the surface of a transparent medium from the back side of the medium, and the watermark image is displayed by the selection means. When it is selected to produce, the watermark is applied to the designated means for designating the area and the style for producing the watermark image and the designated area by the designated means by using an image-forming agent having a color similar to that of the medium. The non-watermarked portion of the watermark image is designated by the designated means by using a transparent image-forming agent for the similar color image forming means for producing the watermark portion of the image according to the designated format by the designated means and the designated area by the designated means. It is an image forming apparatus provided with a transparent image forming means for producing according to a style.

The invention according to claim 2 is a colored image forming means for producing a colored image other than the watermark image by using one or more colored image forming agents on the surface of the medium in the image forming apparatus according to claim 1. It is an image forming apparatus characterized by being provided.
The invention according to claim 3 is an image forming apparatus according to claim 2, wherein the watermark image is covered with a colored image by the colored image forming means.
According to the invention of claim 4, in the image forming apparatus according to claim 1 or 2, the watermark image has the same degree of glossiness as the watermark portion and the non-watermark portion when viewed from the front side of the medium. It is an image forming apparatus characterized by this.
According to the invention of claim 5, when the medium is a white medium in the image forming apparatus according to claim 1 or 4, the watermark image has a watermark portion using a white image-forming agent and the transparent image-forming agent. It is an image forming apparatus characterized by including a non-watermark portion using.
The invention according to claim 6 is the image forming apparatus according to any one of claims 1 to 5, wherein the watermark image is produced by painting a plurality of information strings separately on the watermark portion and the non-watermark portion. It is an image forming apparatus characterized by being present.
The invention according to claim 7 is the image forming apparatus according to any one of claims 1 to 5, wherein the watermark image produces one or a plurality of information strings in either the watermark portion or the non-watermark portion. The image forming apparatus is characterized in that a non-information string other than the information string in the designated area is produced by either the watermark portion or the non-watermark portion.
The invention according to claim 8 is the image forming apparatus according to claim 6 or 7, wherein the watermark image is visually recognized in a normal arrangement state when the medium is viewed through from the back side. It is an image forming apparatus characterized in that the information string is produced as the watermark portion and the non-watermark portion in a state of being flipped horizontally or vertically.
The invention according to claim 9 is a step processing means for reducing or shielding a step at the boundary between the watermark portion and the non-watermark portion constituting the watermark image in the image forming apparatus according to claim 1. It is an image forming apparatus characterized by being provided.
According to the invention of claim 10, in the image forming apparatus according to claim 9, the step processing means increases the amount of heat of fixing of the fixing means for fixing the image produced on the medium more than the normal fixing condition. It is a featured image forming apparatus.
The invention according to claim 11 is the image forming apparatus according to claim 9, wherein the step processing means is transparent so as to reduce a step at a boundary between the watermark portion and the non-watermark portion constituting the watermark image. The image forming apparatus is characterized in that at least the transparent image forming means of the image forming means and the similar color image forming means is used for additional printing.
The invention according to claim 12 is the image forming apparatus according to claim 9, wherein the step processing means is colored so as to shield a step at a boundary between the watermark portion and the non-watermark portion constituting the watermark image. It is an image forming apparatus characterized by performing additional printing by an image forming means.
The invention according to claim 13 is the image forming apparatus according to claim 1, wherein the selection means is selected when an image is produced on the medium in a security mode. Is.
The invention according to claim 14 is the image forming apparatus according to claim 1, wherein when the designated means is selected to produce the watermark image by the selection means, the production area and production of the watermark image. It is an image forming apparatus characterized in that a style is automatically specified.
The invention according to claim 15 is the image forming apparatus according to claim 1 or 14, wherein when the designated means is selected to produce the watermark image by the selection means, the watermark image production area. The image forming apparatus is characterized in that the production mode is variably specified.

The invention according to claim 16 is a watermark portion produced according to a designated format using an image-forming agent having a color similar to that of the medium as a watermark image produced in a predetermined designated area on the surface of a transparent medium. And a non-watermarked portion produced according to a designated format using a transparent image forming agent, and it is possible to visually recognize the shadow of only the watermarked portion of the watermarked image when viewed through the back side of the medium. It is an image structure.

According to the invention of claim 1, the image created in the designated area on the surface of the medium is a watermark image in which the shadow of the image seen through from the back side of the medium is different from the shadow of the image seen from the front side. be able to.
According to the invention of claim 2, a watermark image can be produced on the surface of the medium in addition to the usual colored image.
According to the invention of claim 3, the existence of the watermark image produced on the surface of the medium can be hidden by the colored image.
According to the invention of claim 4, when the watermark image is viewed from the front side of the medium, it is possible to make it difficult to generate a difference in glossiness between the watermark portion and the non-watermark portion.
According to the invention of claim 5, a watermark image can be easily produced on a frequently used white medium.
According to the invention of claim 6, it is possible to easily produce a watermark image in which a plurality of information strings are painted separately in a watermark portion and a non-watermark portion.
According to the invention of claim 7, it is possible to easily produce a watermark image in which the entire one or a plurality of information strings or the periphery of the information string is in a watermark state.
According to the invention of claim 8, when the medium is viewed through from the back side, it is possible to produce a watermark image in which the information strings are visible in a normal arrangement state.
According to the invention of claim 9, it is possible to suppress image quality defects caused by a step at the boundary of the watermark image with respect to the watermark image in which the watermark portion and the non-watermark portion are adjacent to each other.
According to the invention of claim 10, it is possible to reduce the step at the boundary of the watermark image together with the fixing process for the watermark image in which the watermark portion and the non-watermark portion are adjacent to each other.
According to the invention of claim 11, it is possible to reduce the step at the boundary of the watermark image by performing additional printing with a transparent image-forming agent on the watermark image in which the watermark portion and the non-watermark portion are adjacent to each other.
According to the invention of claim 12, it is possible to shield a step at the boundary of a watermark image from a watermark image in which a watermark portion and a non-watermark portion are adjacent to each other through additional printing of a colored image.
According to the invention of claim 13, when creating an image on a medium, it is possible to arbitrarily select whether or not to give a security mode.
According to the invention of claim 14, when the watermark image is produced, the production area and the production mode can be automatically specified.
According to the invention of claim 15, when producing a watermark image, a production area and a production mode can be variably specified.
According to the invention of claim 16, the shadow of the image seen through the back side of the medium is different from the shadow of the image seen from the front side of the image created in the designated area on the surface of the medium. An image structure can be provided.

It is explanatory drawing which shows the outline of embodiment of the image forming apparatus to which this invention was applied. (A) is an explanatory diagram showing an example of a watermark image produced by the image forming apparatus shown in FIG. 1, and (b) is an explanatory diagram showing another example of the watermark image produced by the image forming apparatus. It is explanatory drawing which shows the whole structure of the image forming apparatus which concerns on Embodiment 1. FIG. It is explanatory drawing which shows an example of the drive control system of the image forming apparatus which concerns on Embodiment 1. FIG. It is a flowchart which shows the image formation sequence processing example of the image forming apparatus which concerns on Embodiment 1. FIG. It is a flowchart which shows an example of "watermark tag addition processing" in FIG. (A) is an explanatory diagram showing an example of a production area of a normal image and a watermark image, (b) is an explanatory diagram showing a production example of a normal image, (c) is an explanatory diagram showing a production example of a watermark image, (d). Is an explanatory diagram showing another production example of the watermark image. (A) is an explanatory diagram showing an example of the watermark image shown in FIG. 7 (c), (b) is an explanatory diagram showing the appearance of the actual printed surface of the watermark image of (a), and (c) is the same watermark image. It is explanatory drawing which shows the appearance seen through from the back. It is a flowchart which shows the image formation sequence processing example of the image forming apparatus which concerns on Embodiment 2. An explanatory view showing an example of the watermark image shown in FIG. 7 (d) produced by using the same image forming apparatus, (b) is an explanatory view showing the appearance of the actual printed surface of the watermark image of (a), (c). ) Is an explanatory diagram showing the appearance of the watermark image transparent from the back. (A) is an explanatory diagram showing an example of an image structure that is likely to occur at the boundary between the watermarked portion and the non-watermarked portion of the watermark image shown in FIG. 7 (d), and (b) is at the boundary portion of the watermark image shown in (a). An explanatory diagram showing a method example 1 for reducing or shielding a step, (c) is an explanatory diagram showing the same method example 2, (d) is an explanatory diagram showing the same method example 3, and (e) shows the same method example 4. It is explanatory drawing. It is explanatory drawing which shows the whole structure of the image forming apparatus which concerns on Embodiment 3. It is a flowchart which shows the image formation sequence processing by the server of the image forming apparatus which concerns on Embodiment 3. It is explanatory drawing which shows the whole structure of the image forming apparatus which concerns on Embodiment 4. FIG.

(1) Outline of Embodiment FIG. 1 is an explanatory diagram showing an outline of an embodiment of an image forming apparatus to which the present invention is applied.
In the figure, the image forming apparatus sets the selection means 1 and the selection means 1 for selecting whether or not to produce a watermark image Gt that is visible through the surface of the transparent medium S from the back side of the medium S. When the watermark image Gt is selected to be produced, the designated means 2 for designating the area and the format for creating the watermark image Gt and the designated area Rt by the designated means 2 are of the same color as the medium S. A watermark image using a transparent image-forming agent for a similar color image-forming means 3 for producing a watermark portion Ga of a watermark image Gt using an image-forming agent according to a designated style by the designated means 2 and a designated area Rt by the designated means 2. It is provided with a transparent image forming means 4 for producing a non-watermark portion Gb of Gt according to a designated style by a designated means.
Here, in the image forming apparatus shown in FIG. 1, a colored image forming means 5 for producing a colored image Gc other than the watermark image Gt by using one or more colored image forming agents on the surface of the medium S is provided. For example, the watermark image Gt and the colored image Gc are held by the image holding means 6 to reach the transfer area, and are transferred to the medium S by the transfer means 7 provided in the transfer area, and the transferred images (watermark image Gt, colored image). Gc) is fixed to the medium S via, for example, the fixing means 8. The "image formation" of the similar color image forming means 3, the transparent image forming means 4, and the colored image forming means 5 means "image making", and the "image drawing" is used hereinafter with the same meaning. And.

In such a technical means, the object of the present embodiment is a normal color (typically Y (yellow), M (magenta), C (cyan), K (black), white, and clear (transparent). Any image forming apparatus provided with an image-forming agent may be used, and both a one-unit configuration and a two-unit configuration are included.
Further, the medium S is not limited to white, but also broadly includes other colored media (including black as long as it has transparency).
Further, the watermark image Gt means an image created on the surface of the medium S and visible when viewed from the back side of the medium S, and the watermark portion (visible portion) Ga and the non-watermark portion (not transparent). Part) It shall have Gb.
Here, the watermark portion Ga may be broadly included as long as it is produced by using an image-forming agent having a color similar to that of the medium S, and the non-watermark portion Gb may be produced by using a transparent image-forming agent.

Next, a typical mode or a preferable mode of the image forming apparatus according to the present embodiment will be described.
Since this example includes the colored image forming means 5, it is possible to produce the colored image Gc separately from the watermark image Gt. For example, the colored image Gc produced by the colored image forming means 5 for the watermark image Gt. It is also possible to directly hide the watermark image Gt by covering it with.
A preferred embodiment of the watermark image Gt is a mode in which the watermark portion Ga and the non-watermark portion Gb have the same degree of gloss when viewed from the front side of the medium S. In this example, by making the watermark portion Ga and the non-watermark portion Gb of the watermark image Gt comparable in glossiness, it is possible to suppress the watermark image from being conspicuous due to the difference in glossiness when the medium S is viewed from the front side. Is intended.
As a typical aspect of the watermark image Gt, when the medium S is a white medium, the watermark image Gt includes a watermark portion Ga using a white image-forming agent and a non-watermark portion Gb using a transparent image-forming agent. Aspects including.

Further, as a typical embodiment of the watermark image Gt as a configuration example, as shown in FIG. 2A, there is an example in which a plurality of information strings are painted separately on the watermark portion Ga and the non-watermark portion Gb. .. Here, the "information" of the "information string" includes "symbols", "numbers", etc. other than "characters".
In FIG. 2A, on the front side of the medium S, the even-numbered portion of the five information strings is the watermark portion Ga (specifically, Ga1 and Ga2), and the odd-numbered portion is the non-watermark portion Gb (specifically, Gb1 to Gb1). Gb3) is given as an example. Since the watermark portion Ga and the non-watermark portion Gb form an image portion made of an image-forming agent having the same color or a transparent color as the surface of the medium S, the medium S It is formed in an indistinguishable state with respect to the surface color. Therefore, the watermark image Gt is seen integrally with the surface color of the medium S when viewed from the front side of the medium S, which makes it difficult to see. However, since the watermark image Gt has a higher glossiness than the surface of the medium S, it is possible to confirm the existence of the information string by the watermark image Gt when looking closely.
Since the transparency between the watermark portion Ga and the non-watermark portion Gb is "watermark portion Ga (white image forming agent) <non-watermark portion Gb (transparent image forming agent)", the watermark image Gt is used as the back of the medium S. When viewed through the watermark, it is possible to visually recognize only the watermark portion Ga (specifically, Ga1 and Ga2) in an inverted state (in this example, a left-right inverted state).

Further, as another typical embodiment as a configuration example of the watermark image Gt, as shown in FIG. 2B, one or a plurality of information strings are produced in either the watermark portion Ga or the non-watermark portion Gb. , An embodiment in which a non-information string other than the information string in the designated area Rt is produced by either the watermark portion Ga or the non-watermark portion Gb can be mentioned.
In FIG. 2B, on the front side of the medium S, all five information strings are set as watermark portions Ga (specifically, Ga1 to Ga5), and the entire area of the non-information string other than the information string in the designated area R is covered. The non-watermarked portion Gb is taken as an example, and the watermarked portion Ga and the non-watermarked portion Gb constitute an image portion made of an image-forming agent having the same color or a transparent color as the surface of the medium S in the entire designated area R. Therefore, it is formed in a state in which it is indistinguishable from the surface color of the medium S. Therefore, the watermark image Gt is seen integrally with the surface color of the medium S when viewed from the front side of the medium S, which makes it difficult to see.
Then, when the watermark image Gt is viewed through from the back of the medium S due to the difference in transmittance between the watermark portion Ga and the non-watermark portion Gb, the information sequence as the watermark portion Ga (specifically, Ga1 to Ga5) is inverted. It is possible to visually recognize the image in the state (in this example, the left-right inverted state).

Further, as described above, when an information string as a watermark image Gt is created on the front side of the medium S in a normal arrangement state, the information string appears in an inverted state when viewed through the back side of the medium S. A situation occurs in which the image Gt is somewhat difficult to read.
From the viewpoint of eliminating such a situation, as a preferred embodiment of the watermark image Gt, the information sequence is flipped horizontally or vertically so that the information sequence is visually recognized in a normal arrangement state when the medium S is viewed through from the back side. Examples thereof include an embodiment in which the watermark portion Ga and the non-watermark portion Gb are produced in the inverted state. In this example, the information sequence is flipped horizontally or vertically in advance when the information sequence is created so that the information sequence can be visually recognized as a normal arrangement state when viewed from the back side.

Further, as shown in FIG. 2B, an information string as a watermark image Gt is produced on one side of the watermark portion Ga or the non-watermark portion Gb, and the watermark portion Ga or the non-watermark portion Gb is in close contact with the surroundings thereof. On the other hand, in the aspect of producing, if a step is generated at the boundary between the watermark portion Ga and the non-watermark portion Gb, the step portion is visually recognized when the medium S is viewed from the front side, and the watermark image Gt. There is a concern that the existence will be easily exposed directly.
From the viewpoint of eliminating such concerns, it is preferable to provide a step processing means 9 for processing so as to reduce or shield the step at the boundary between the watermark portion Ga and the non-watermark portion Gb constituting the watermark image Gt.

Here, for example, the following can be mentioned as a typical aspect of the step processing means 9.
(1) An embodiment in which the amount of heat for fixing the fixing means 8 for fixing the image produced on the medium S is increased more than the normal fixing conditions. This is intended to melt and level the step at the boundary between the watermark portion Ga and the non-watermark portion Gb by increasing the amount of heat of fixing by the fixing means 8.
(2) Reprinting by at least the transparent image forming means 4 of the transparent image forming means 4 and the similar color image forming means 3 so as to reduce the step at the boundary between the watermark portion Ga and the non-watermark portion Gb constituting the watermark image Gt. Aspects for carrying out. In this example, the step of the boundary described above is covered by additional printing with a transparent image-forming agent.
(3) An embodiment in which reprinting is performed by the colored image forming means 5 so as to shield the step at the boundary between the watermark portion Ga and the non-watermark portion Gb constituting the watermark image Gt. In this example, the step processing means 9 is formed by utilizing the additional printing of the colored image Gc.
(4) In order to reduce the step at the boundary between the watermark portion Ga and the non-watermark portion Gb constituting the watermark image Gt, both the transparent image forming agent and the similar color image forming agent are mixed around the boundary described above. It is an aspect of partially converting image data into.

Further, as a preferred embodiment of the selection means 1, there is an embodiment selected when an image is produced for the medium S in the security mode. In this example, a security mode for imparting safety to the image production for the medium S is created, the mode is selected, and the watermark image Gt is used as a safety measure.
Further, as a typical aspect of the designating means 2, there is an aspect in which when the selection means 1 selects to produce the watermark image Gt, the production area and the producing mode of the watermark image Gt are automatically designated. .. This example is a method of automatically designating the production area and production mode of the watermark image Gt without injuring the user's hands.
Further, as another typical aspect of the designation means 2, when the selection means 1 selects to produce the watermark image Gt, the production area and the production mode of the watermark image Gt are variably designated. .. In this example, the intention of the user can be reflected in the production of the watermark image Gt.

Further, in the present embodiment, the image forming apparatus for producing the watermark image Gt is not limited to the image forming apparatus itself, and the image structure itself of the watermark image Gt also has a new configuration.
That is, as the watermark image Gt produced in the predetermined designated region Rt on the surface of the medium S having transparency, the watermark portion Ga produced according to the designated style using an image-forming agent of the same color as the medium S. It has a non-watermark portion Gb produced according to a specified format using a transparent image forming agent, and it is possible to visually recognize the shadow of only the watermark portion Ga of the watermark image Gt when viewed through the back side of the medium S. The image structure to be used is mentioned.

Hereinafter, the present invention will be described in more detail based on the embodiments shown in the accompanying drawings.
◎ Embodiment 1
FIG. 3 is an explanatory diagram showing the overall configuration of the image forming apparatus according to the first embodiment.
-Overall configuration of image forming apparatus-
In the figure, the image forming apparatus 20 has a plurality of color components (clear (CL), yellow (Y), magenta (M), cyan (C), black in the present embodiment) in the image forming apparatus housing 21. (K), white (W)) The image forming unit 22 (specifically, 22a to 22f) forming the image and each color component image formed by each image forming unit 22 are sequentially transferred (primary transfer) and held. A belt-shaped intermediate transfer body 30, a secondary transfer device (batch transfer device) 50 that secondarily transfers (batch transfer) each color component image transferred on the intermediate transfer body 30 to a paper as a recording medium, and a secondary. It includes a fixing device 70 for fixing the transferred image on the paper, and a paper transport system 80 for transporting the paper to the secondary transfer region.

-Image forming part-
In the present embodiment, each image forming unit 22 (22a to 22f) has a drum-shaped photoconductor 23, and around each photoconductor 23, a corotron, a charging roll, or the like on which the photoconductor 23 is charged is charged. The electrostatic latent image written on the charging device 24, the exposure device 25 such as a laser scanning device in which the electrostatic latent image is written on the charged photoconductor 23, and the electrostatic latent image written on the photosensitive member 23 are developed with each color component toner. The developing device 26, the primary transfer device 27 such as a transfer roll in which the toner image on the photoconductor 23 is transferred to the intermediate transfer body 30, and the photoconductor cleaning device 28 from which the residual toner on the photoconductor 23 is removed are respectively arranged. It is a thing.
Further, the intermediate transfer body 30 is hung on a plurality of tension rolls 31 to 33 (three in the present embodiment), for example, a drive roll in which the tension roll 31 is driven by a drive motor (not shown). It is used as a motor and is circulated by the drive roll. Further, an intermediate transfer body cleaning device 35 for removing residual toner on the intermediate transfer body 30 after the secondary transfer is provided between the tension rolls 31 and 33.

-Secondary transfer device (batch transfer device)-
Further, in the secondary transfer device (batch transfer device) 50, as shown in FIGS. 3 and 4, the transfer roll 55 is pressure-welded to the portion of the intermediate transfer body 30 facing the tension roll 33, and the intermediate transfer body 30 is pressed. The tension roll 33 of 30 is used as an opposing roll 56 forming an opposing electrode of the transfer roll 55. Here, in this example, the transfer roll 55 has a structure in which an elastic layer in which urethane foam rubber or EPDM is mixed with carbon black or the like is coated around a metal shaft, and the transfer roll 55 and the opposing roll 56 are combined. The nip region of the intermediate transfer body 30 sandwiched between the two is made to function as a secondary transfer region (collective transfer region) TR.
Furthermore, the transfer voltage from the transfer power supply 60 is applied to the opposing roll 56 (also used as the tension roll 33 in this example) via the conductive feeding roll 57, and the transfer voltage is applied between the transfer roll 55 and the opposing roll 56. A predetermined transfer electric field is formed.
In this example, the secondary transfer device 50 has a mode in which the transfer roll 55 is pressure-welded to the intermediate transfer body 30, but the present invention is not limited to this, and the transfer roll 55 is used as one of the tensioning rolls for the transfer belt. It goes without saying that a belt transfer module or the like may be used to hang the belt between the tension rolls.

-Fixing device-
As shown in FIG. 3, the fixing device 70 is placed in contact with the image holding surface side of the paper S and is placed in contact with a drive-rotatable heat fixing roll 71, and is pressure-welded and placed facing the heat fixing roll 71 to heat. It has a pressure fixing roll 72 that rotates following the fixing roll 71, and an image held on the paper S is passed through a fixing region between the fixing rolls 71 and 72, and the image is heat-pressed and fixed. It is a thing.

-Paper transport system-
Further, as shown in FIG. 3, the paper transport system 80 has a plurality of stages (two stages in this example) of paper supply containers 81 and 82, and the paper S supplied from any of the paper supply containers 81 and 82. From the vertical transport path 83 extending in the substantially vertical direction to the secondary transfer region TR via the horizontal transport path 84 extending in the substantially horizontal direction, and then the paper on which the transferred image is held is passed through the transport belt 85. It reaches the fixing portion by the fixing device 70 and discharges the paper to the paper discharge receiver 86 provided on the side of the image forming apparatus housing 21.
Further, the paper transport system 80 has a reversible branch transport path 87 that branches downward from a portion of the horizontal transport path 84 located on the downstream side in the paper transport direction of the fixing device 70, and the branch transport path The paper S inverted in 87 is returned from the vertical transport path 83 to the horizontal transport path 84 via the return transport path 88, the image is transferred to the back surface of the paper S in the secondary transfer region TR, and the image is transferred through the fixing device 70. It is designed to be ejected to the paper ejection receiver 86.
Further, in the paper transport system 80, in addition to the position matching roll 90 that aligns the position of the paper S and supplies it to the secondary transfer area TR, an appropriate number of transport rolls 91 are provided in each of the transport paths 83, 84, 87, 88. It is provided. Further, a guide chute 93 for guiding the paper S that has passed through the position matching roll 90 to the secondary transfer area TR is provided on the inlet side of the secondary transfer area TR of the horizontal transport path 84. In this example, one guide chute 93 is provided between the position matching roll 90 and the secondary transfer region TR, and the guide chute 93 of the paper S is guided by arranging the pair of metal chute members facing each other. It is designed to regulate the trajectory.
Furthermore, on the opposite side of the paper discharge receiver 86 of the image forming apparatus housing 21, a manual paper feeder 95 capable of supplying manual paper toward the horizontal transport path 84 is provided.

-Paper type indicator-
As the paper S that can be used in this example, not only ordinary blank paper (plain paper, coated paper, etc.) but also special paper such as black paper can be applied.
For example, when black paper is used as special paper, a mode in which a background image (for example, a white image) is created on the surface of the paper and a colored image of various color components is created on the background image (image with background). Will need to be selected.
Therefore, in the present embodiment, as shown in FIG. 4, a paper type classifier 100 for specifying the paper type is provided. In this example, as the paper type classifier 100, as shown in FIG. 4, for example, the operation panel as a user interface is provided with a paper type indicator, and the paper that can be used in the image forming apparatus is registered in advance. Among them, there is one that indicates the type of paper to be used.
Further, as another example of the paper type classifier 100, a discriminator for discriminating the color of the paper type is installed in a part of the vertical transport path 83 or the horizontal transport path 84 of the paper transport system 80, and the discriminator is used. The color of the paper to be used may be determined.

-Drive control system of image forming device-
In the present embodiment, as shown in FIG. 4, reference numeral 120 is a control device for controlling the image formation process of the image forming apparatus, and the control device 120 is a microcomputer including a CPU, ROM, RAM, and an input / output interface. It consists of switch signals such as a start switch (not shown) and a mode selection switch for selecting an image drawing mode via an input / output interface, various sensor signals, and a paper type from a paper type classifier 100 that specifies a paper type. After taking in various input signals such as specific signals, executing the image formation sequence processing program (see FIG. 5) stored in advance in the ROM on the CPU to generate control signals for the drive control target, each drive control target (see FIG. 5). A control signal is sent to the image forming unit 22 (22a to 22f), the transfer power supply 60, etc.).

-Operation of image forming device-
Next, assuming that different types of paper S are mixedly used in the image forming apparatus shown in FIGS. 3 and 4, first, as shown in FIG. 5, the user uses an operation panel (not shown). After deciding whether or not to specify the security print selection switch, a start switch (not shown) may be turned on to start printing (image processing) by the image forming apparatus.
At this time, the paper S is supplied from either the paper supply containers 81, 82 or the manual feed paper feeder 95, is conveyed toward the secondary transfer region TR via a predetermined transfer path, and is conveyed to the control device 120. The paper information from the type specifier 100 is input, and the paper type to be used is specified.

In the present embodiment, when the security print is specified, the control device 120 specifies the area and the format of the watermark image in addition to the production of the normal image. The "watermark image Gt" referred to here is, for example, as schematically shown in FIG. 7A, is produced in a predetermined designated area Rt on the front side of the paper S according to a designated format, and is a paper. It is assumed that the image is drawn in a state in which it is difficult to distinguish it from the front surface of the paper S when viewed from the front side of the S, and a part of the watermark image Gt is visible when viewed through the back side of the paper S. In FIG. 7A, the reference numeral Rm indicates an image forming area for producing the normal image Gm, and the designated area Rt of the watermark image Gt is often selected at a position different from the designated area Rm of the normal image Gm. ..
Further, regarding the designation of the watermark image Gt, it is preferable to automatically specify the watermark image Gt based on the information recorded in advance in the RAM of the control device 120 so that the user's hand is not affected. If there is a request to change the area or format of the watermark image each time, the user may change and specify the watermark image as appropriate.

<Structure example of normal image and watermark image>
In this example, as shown in FIGS. 7A and 7B, the normal image Gm is generally an image produced by the image forming units 22b to 22e using YMCK toner, but is limited to this. Instead, the image-forming unit 22a uses the clear (CL) toner to impart gloss, or the image-forming unit 22f uses the white (W) toner to add a white image.
Further, as shown in FIGS. 7A and 7C, the watermark image Gt is a character string which is an example of an information string designated according to a designated format (in this example, a character string is shown from five characters). home. For example, the even-numbered (2nd and 4th) characters are used as the watermark Ga with white (W) toner, and the odd-numbered (1, 3, 5) characters are used as the non-watermark Gb with clear (CL) toner. is there. The designated format here refers to the contents of an information string consisting of a character string, a symbol string, a code string, or a combination thereof, as well as various formats related to the font and size of the information string, the watermark portion Ga, and the layout of the non-watermark portion Gb. In addition, image images may be specified as various formats instead of information strings.
The layout of the watermark portion Ga and the non-watermark portion Gb is not limited to the above-mentioned method (even / odd number), and is automatically determined by, for example, prime / non-prime number, binary number counting, random number, or the like. It does not matter if you paint them separately.

<Adding a watermark tag>
After that, as shown in FIG. 6, the control device 120 adds a watermark tag to each pixel when rasterizing (corresponding to pixelization) each image.
In this example, the "watermark tag" is a tag that serves as a marker for distinguishing between the normal image Gm and the watermark image Gt, and further distinguishing whether the watermark image Gt is the watermark portion Ga or the non-watermark portion Gb. Pointing, for example, it is decided as follows.
Watermark tag '0': Pixels constituting the normal image Gm 〃 '1': Non-watermark part Gb (clear (CL))
〃 '2': Watermark Ga (white (W))
In the example shown in FIG. 7 (c), the image of the normal image Gm is '0', the odd-numbered non-watermark portion Gb of the watermark image Gt is '1', and the even-numbered watermark portion Ga of the watermark image Gt is'. 2'is given.

On the other hand, when the security print is not specified, as shown in FIG. 5, it is not necessary to create the watermark image Gt. Therefore, when rasterizing, the normal image Gm is created without adding a watermark tag. It should be.

Then, when the rasterization process (including the watermark tag addition process in the security print) is completed, the control device 120 color-converts the pixels of the normal image Gm (including the pixels of the watermark tag '0') according to a known color conversion method. You just have to do it. Regarding the watermark image Gt, the pixel with the watermark tag '1' is given 100% clear (CL) toner (not necessarily 100%) regardless of the pixel value, and the watermark tag '2' The pixel may be provided with 100% (not necessarily 100%) white (W) toner regardless of the pixel value.
After that, the control device 120 decomposes the image data into data for each color plate, sends the data to each color processing unit, performs halftone dot processing and the like to generate each color plate, and then the image forming unit 22. The print may be performed at (22a to 22f).

-Specific example of watermark image Gt-
In the present embodiment, as shown in FIG. 8A, when the paper S is a blank paper (for example, a transparent white coated paper), the character string is'aiueo'as the information string of the watermark image Gt. Assuming that the odd-th character'Auo'is the non-watermark part Gb (clear toner part) and the even-th character'No'is the watermark part Ga (white toner part), the watermark image printed on blank paper as paper S. The watermark portion Ga and the non-watermark portion Gb of Gt have the same color and glossiness, and as shown in FIG. 8B, it is difficult to distinguish the appearance of the actual printed surface. The dotted line notation in FIG. 8 has a similar color to the S surface of the paper without the watermark image Gt, but there is a gloss difference at the boundary portion of the watermark image Gt. Therefore, if you look closely, you can see that the watermark image Gt. It indicates a state in which the existence is noticeable.
On the other hand, as shown in FIG. 8C, the appearance of the watermark image Gt on the blank paper as the paper S transparent from the back is a state in which only the watermark portion Ga (white toner portion),'No', is transparent. It is visually recognized by.
However, in this example,'No' is visually recognized in a left-right inverted state.

◎ Embodiment 2
FIG. 9 is a flowchart showing an image forming sequence process used in the image forming apparatus according to the second embodiment.
In the figure, the basic configuration of the image formation sequence processing is substantially the same as that of the first embodiment, but the designation format of the watermark image Gt is partially different from that of the first embodiment.
That is, in this example, as shown in FIG. 7D, the watermark image Gt has all the character strings (five character strings in this example) as information strings in the designated area Rt as the watermark portion Ga (white toner). Part), and all areas other than the character string in the designated area Rt are produced as the non-watermark part Gb (clear toner part).
Further, in this example, when the security print is specified, the control device 120 sees the watermark image Gt from the back in addition to the watermark tag addition process when rasterizing the watermark image Gt. In this example, the watermark image Gt (watermark portion Ga, non-watermark portion Gb) is created in a state where each pixel is horizontally inverted in advance so that the character strings constituting the watermark image Gt are arranged in a regular arrangement state. It is designed to be converted into image data for the purpose.

After that, the control device 120 decomposes the left-right inverted image data into data for each color plate, sends the data to each color processing unit, performs halftone dot processing, and the like to generate each color plate. Printing is performed by the image forming unit 22 (22a to 22f).
Therefore, in the present embodiment, the watermark image Gt is produced in a state of being horizontally inverted on a blank sheet of paper S, and the watermark portion Ga and the non-watermark portion Gb are within the designated region Rt with substantially the same glossiness. Since they are arranged in close contact with each other, it is difficult to distinguish the watermark image Gt when viewed from the front side, and when viewed through from the back side, the watermark portion Ga in the normal arrangement state is visible, as in the case of the first embodiment. Will be done.

-Specific example of watermark image Gt-
In the present embodiment, as shown in FIG. 10A, when the paper S is a blank paper (for example, a transparent white coated paper), the character string is'aiueo'as the information string of the watermark image Gt. , This character string that is the left-right reversal of'aiueo'is created as the watermark part Ga (white toner part), and the non-watermark part Gb (clear toner part) is created in the area other than the character string of the designated area Rt, and the watermark is created. It is arranged in close contact with the portion Ga.
At this time, the watermark portion Ga and the non-watermark portion Gb of the watermark image Gt printed on the blank paper as the paper S have the same color and glossiness, and the boundary between the character string which is the watermark portion Ga and the non-watermark portion Gb. Since the presence of the part is not noticeable at all, as shown in FIG. 10B, the actual appearance of the printed surface is invisible, and not only the existence of the character string of the watermark image Gt but also the character string is reversed left and right. It is also difficult to determine that it is manufactured in the state of being watermarked.
On the other hand, as shown in FIG. 10 (c), the appearance of the watermark image Gt on the blank paper as the paper S seen through from the back is that the watermark portion Ga (white toner portion) of'aiueo'is in a normal arrangement state. It is visible in a transparent state.
In the present embodiment, since the watermark image Gt is a character string as a horizontally arranged information string (corresponding to a horizontal array), a method of flipping left and right is adopted when processing the data of the watermark image Gt. For example, when the watermark image Gt is a vertical arrangement (corresponding to a vertical arrangement), a method of inverting the top and bottom may be adopted when processing the data of the watermark image Gt.

-Step processing-
In the present embodiment, as shown in FIG. 11A, in the watermark image Gt, the watermark portion Ga (white toner portion) and the non-watermark portion Gb (clear toner portion) are closely arranged, and the watermark A step Δh is likely to occur at the boundary between the portion Ga and the non-watermark portion Gb. With this step Δh, for example, when looking at the watermark image Gt on a blank sheet of paper S, the boundary portion between the watermark portion Ga and the non-watermark portion Gb becomes easily visible, and the presence of the watermark image Gt becomes easily noticeable. In such a situation, considering that the watermark image Gt is used at the time of designating the security print, it is preferable that the presence of the watermark image Gt is inconspicuous.
Therefore, in the present embodiment, a step treatment for reducing or shielding the step Δh at the boundary between the watermark portion Ga and the non-watermark portion Gb is performed.

(1) Step processing using the fixing device 70 In this example, as shown in FIG. 11B, under the condition that the watermark portion Ga and the non-watermark portion Gb of the watermark image Gt are closely arranged. In order to reduce the step at the boundary between the watermark portion Ga and the non-watermark portion Gb, the fixing temperature _TF , which is the fixing condition of the fixing device 70, is set higher than the normal condition, for example, 10 ° C., or the fixing device 70 It is intended to carry out the fixing process twice in the above to supply a larger amount of fixing heat to the boundary portion between the watermark portion Ga and the non-watermark portion Gb, and to melt and reduce the step portion.

(2) Step processing by reprinting of clear toner In this example, as shown in FIG. 11C, under the condition that the watermark portion Ga and the non-watermark portion Gb of the watermark image Gt are closely arranged. In order to reduce the step at the boundary between the watermark portion Ga and the non-watermark portion Gb, a reprint portion Gd with clear toner is laminated on both of them, and the above-mentioned step portion is filled and reduced. ..

(3) Step processing near the boundary between the watermarked portion and the non-watermarked portion In this example, FIG. 11 (d) is under the condition that the watermarked portion Ga and the non-watermarked portion Gb of the watermark image Gt are closely arranged. ), The image data is converted so that the clear toner and the white toner are mixed at m near the boundary between the watermark portion Ga and the non-watermark portion Gb, and the watermark portion Ga and the non-watermark portion Gb are combined. It is designed to reduce the step at the boundary. In this example, in the vicinity of the boundary, for example, the amount of clear toner may be gradually reduced toward the watermark portion Ga, and conversely, the amount of white toner may be gradually increased toward the non-watermark portion Gb.
(4) Step processing by reprinting of another image This example is shown in FIG. 11 (e) under the condition that the watermark portion Ga and the non-watermark portion Gb of the watermark image Gt are closely arranged. In order to reduce the step at the boundary between the watermark portion Ga and the non-watermark portion Gb, a reprint portion Ge with another colored toner (for example, YMC toner) is laminated on both of them to shield the above-mentioned step portion. It is something like that.

◎ Embodiment 3
-Overall configuration of image forming apparatus-
FIG. 12 shows the overall configuration of the image forming apparatus according to the third embodiment.
In the figure, the image forming apparatus includes one or a plurality of client PCs (abbreviation of Personal Computer) 200 installed as an example of an information processing apparatus, and two image output devices (IOT (abbreviation of Image Output Terminal) in FIG. 2). 1. IOT2) 211,212, and a server 230 that connects the client PC 200 and the two image output devices 211,212 so as to be communicable via a network.

-Client PC-
In this example, the client PC 200 has a computer main body equipped with a control device (not shown) including a CPU, a ROM, a RAM, and a microcomputer including an input / output port, and the computer main body has a display as a display means. , A keyboard and mouse as input means are connected.
Then, the user comprises an image to be output by the image output devices 211 and 212 in the client PC 200 (for example, an image composed of general colors of a plurality of general color components and a special color other than the general color (hereinafter referred to as a special color). A combination image with an image) is created, and these image data DTs and medium information for outputting the image are transmitted to the server 230.

-Image output device-
In this example, as shown in FIG. 12, the image output device 211 (corresponding to IOT1) is equipped with an image-forming engine that forms an image of general colors in the device housing, and further includes an image-forming engine. A control device 221 including a microcomputer for controlling each element is provided.
Further, as shown in FIGS. 2 and 3, the image output device 212 (corresponding to IOT2) is equipped with an image-forming engine that forms an image having special colors in the device housing, and further includes an image-forming engine. A control device 222 for controlling each element is provided.
Here, the image composed of general colors refers to an image composed of, for example, yellow (Y), magenta (M), cyan (C), and black (K) as a plurality of color components in this example. Further, the image composed of special colors refers to an image using any of white, gold, silver, and clear (CL) corresponding to transparency in this example.
The configuration examples of the image output devices 211 and 212 are substantially the same as those of the image forming device of the first embodiment.
However, the basic configuration of the image output device 212 is different from that of the image output device 211, and the image forming unit 22 (specifically, 22e to 22h) has a plurality of features (white, gold, silver, and clear (in the present embodiment). It forms the image of CL)).

-Server-
In this example, as shown in FIG. 12, the server 230 includes a control device 231 that controls each image output device 211,212 based on the information acquired from the client PC 200. In this example, the control device 231 includes a CPU, a ROM, a RAM, and a microcomputer including an input / output port, and the ROM has an image forming program (see FIG. 13) that determines an image forming sequence of each image output device 211,212. The image formation conditions (images) of the image output devices 211 and 212 are obtained from the general color + special color image data DT and paper type information acquired from the client PC 200 by executing the image drawing program on the CPU, which is installed in advance. The formation order) is determined, and the general color image data DT1 is supplied to the image output device (IOT1) 211, and the special color image data DT2 is supplied to the image output device (IOT2) 212 at a predetermined timing. ing.

-Image sequence by server-
Next, the image formation sequence processing by the server 230 will be described with reference to FIG.
As shown in FIG. 13, when the control device 231 of the server 230 first acquires the image data DT from the client PC 200, it checks whether or not the security print is specified, and if it is specified, the security print is specified. A watermark image Gt is added to the normal image Gm to create an image.
On the other hand, if the security print is not specified, only the normal image Gm is imaged.
After that, the control device 231 checks whether or not the image data DT is "general color + spot color".
Then, when the image data DT is not "general color + special color", that is, when the image data DT is only general color, a paper set is set on the operation panel of the image output device (IOT1) 211 which is a general color machine. The display is performed, and the image is drawn only by the image output device 211 in a state where the paper S has been set.
When the image data DT has only special colors, the paper set is displayed on the operation panel of the image output device (IOT2) 212, which is a special color machine, and only the image output device 212 is used when the paper S has been set. Perform image drawing.

Further, when the image data DT is "general color + special color", the control device 231 of the server 230 displays the paper set on the operation panel of the image output device (IOT1) 211 which is a general color machine, and displays the paper set on the paper S. Image drawing is performed by the image output device 211 in a state where the setting of is completed. Next, the paper set printed by IOT1 is displayed on the operation panel of the image output device (IOT2) 212, which is a spot color machine, and image drawing is performed by the image output device 212 in a state where the paper S has been set.
In particular, as the "feature", the watermark portion Ga and the non-watermark portion Gb constituting the watermark image Gt may be produced in the same manner as in the first and second embodiments.

◎ Embodiment 4
FIG. 14 shows a main part of the image forming apparatus according to the fourth embodiment.
In the figure, as the image forming apparatus, the image output device (IOT1) 211 as a general color machine is installed on the front stage side, and the image output device (IOT2) 212 as a spot color machine is installed on the rear stage side. The paper transport paths of the image output devices 211 and 212 are connected via 213, and a paper supply device 210 is installed on the front stage side of the image output device (IOT1) 211 to be installed after the image output device (IOT2) 212. An aftertreatment device (finisher) 214 is installed on the side.
Then, the client PC 200 is communicably connected to the image output device (IOT1, IOT2), the paper supply device 210, the relay transfer device 213, and the post-processing device 214 via the server 230.
In this example, the paper feeder 210 has a plurality of paper feeders 241 and some of them have a manual feed paper feeder 242. Further, the paper supply device 210 is provided with an operation unit (including an input unit and a display unit) 243.
Further, the basic configurations of the image output devices (IOT1, IOT2) 211 and 212 are substantially the same as those in the third embodiment, and the image forming engine (image forming unit 22, intermediate transfer body 30, batch transfer device 50) is contained in the device housing. ) Is mounted, and further, a fixing device 70 for image fixing is mounted, and control devices 221, 222 are provided, respectively.
Here, the control devices 221 and 222 may adopt the configuration of the third embodiment.
Further, the relay transfer device 213 has a manual feed inserter 245 and a relay transfer path 246 for connecting the medium transfer paths of the image output devices (IOT1, IOT2) 211 and 212 located in the front and rear positions.
Furthermore, the post-processing device 214 has a puncher 251 and an edge binding device 252, a saddle stitching device 253, and a paper ejection receiver 254, and further has a manual feed inserter 255.

In the present embodiment, paper is supplied from the paper feeder 241 and the manual feed paper feeder 242 of the paper supply device 210, and the image output device (IOT1) 211 as a general color machine, the relay transfer device 213, and the special color machine are used. The paper is discharged to the paper discharge receiver 254 via the image output device (IOT2) 212 and the post-processing device 214.
Therefore, in the present embodiment, assuming that the server 230 determines the printing order (image formation order) of "general color-> spot color", the paper supplied from the paper supply device 210 outputs an image as a general color machine. Image drawing is performed by the device (IOT1) 211, and the first fixing process is performed by the fixing device 70. After that, the paper printed by the image output device (IOT1) 211 is guided to the image output device (IOT2) 212 as a special color machine via the relay transfer device 213, and the image is drawn by the image output device (IOT2) 212. Then, the fixing device 70 performs the second fixing process. After that, the paper containing the "general color image + special color image" is discharged to the paper discharge receiver 254 via the post-processing device 214.
In this way, in the case of this example, in the case of the printing order (image formation order) of "general color-> spot color", the paper is automatically carried into the image output devices (IOT1, IOT2) 211,212. Image drawing and fixing processing are carried out.
In this example as well, as the "special color", the watermark portion Ga and the non-watermark portion Gb constituting the watermark image Gt may be produced in the same manner as in the first and second embodiments.

However, when the server 230 is in the printing order (image formation order) of "special color-> general color", for example, the image output device (IOT1) 211 as a general color machine does not perform image drawing, and the image is output as a special color machine. Image drawing by the device (IOT2) 212 may be performed, and the paper supplied from the paper supply device 210 is relayed through the paper transport path in the image output device (IOT1) 211 as a general color machine. After being guided from 213 into the image output device (IOT2) 212 as a special color machine, image drawing is performed by the image output device (IOT2) 212, and the images are discharged to the paper ejection receiver 254 via the post-processing device 214.
After that, the special color image printed paper discharged to the paper ejection receiver 254 is manually set in the paper supply device 210, imaged and fixed by the image output device (IOT1) 211 as a general color machine, and then relayed and conveyed. The paper may be discharged to the paper discharge receiver 254 via the paper transport path of the device 213, the image output device (IOT2) 212, and the post-processing device 214.
In this case, the printed paper is manually transported, but it is needless to say that the printed paper may be automatically transported by a separately installed transport unit.

In the present embodiment, in the case of the printing order (image formation order) of "general color-> spot color", image drawing and fixing processing are continuously performed by the image output devices (IOT1, IOT2) 211 and 212. For example, the fixing device 70 of the image output device (IOT1) 211 as a general color machine may be assumed to be attached, and the fixing device 70 of the image output device (IOT2) 212 as a spot color machine may be used for main fixing. In this example, it is possible to reduce the power required for the fixing device 70 as compared with the case where both fixing devices 70 are used for main fixing.
In the present embodiment, two image output devices (IOT1, IOT2) 211 and 212 are used in each case, but the present invention is not limited to this, and two sets of images are created in one device housing. The engines may be continuously arranged and each may be equipped with a fixing device for fixing an image formed by each image-forming engine.

In all of the present embodiments, a watermark image Gt that can be visually recognized by seeing through the paper S from the back side is produced, but safety measures at the time of security printing can be applied to various measures, and in particular, a high-precision printed matter. It can also be effectively used as an anti-counterfeiting technology.

1 ... Selective means, 2 ... Designated means, 3 ... Similar color image forming means, 4 ... Transparent image forming means, 5 ... Colored image forming means, 6 ... Image holding means, 7 ... Transfer means, 8 ... Fixing means, 9 ... Step processing means, Gc ... colored image, Gt ... watermark image, S ... medium

Claims (16)

A selection means for selecting whether or not to produce a watermark image that can be visually recognized through the surface of a transparent medium from the back side of the medium.
When the selection means selects to produce the watermark image, the designation means for designating the area and the style for producing the watermark image, and
A similar color image forming means for producing a watermark portion of the watermark image according to a designated style by the designated means by using an image forming agent of the same color as the medium for a designated area by the designated means.
A transparent image forming means for producing a non-watermarked portion of the watermark image according to a designated style by the designated means by using a transparent image forming agent for a designated area by the designated means.
An image forming apparatus characterized by being provided with. In the image forming apparatus according to claim 1,
An image forming apparatus comprising: a colored image forming means for producing a colored image other than the watermark image by using one or more colored image forming agents on the surface of the medium. In the image forming apparatus according to claim 2,
An image forming apparatus, characterized in that the watermark image is covered with a colored image by the colored image forming means. In the image forming apparatus according to claim 1 or 2.
The watermark image is an image forming apparatus characterized in that the watermark portion and the non-watermark portion have the same degree of glossiness when viewed from the front side of the medium. In the image forming apparatus according to claim 1 or 4.
An image forming apparatus characterized in that when the medium is a white medium, the watermark image includes a watermark portion using a white image forming agent and a non-watermark portion using the transparent image forming agent. In the image forming apparatus according to any one of claims 1 to 5,
The image forming apparatus is characterized in that the watermark image is produced by painting a plurality of information strings separately on the watermark portion and the non-watermark portion. In the image forming apparatus according to any one of claims 1 to 5,
In the watermark image, one or a plurality of information strings are produced in either the watermark portion or the non-watermark portion, and the non-information strings other than the information string in the designated area are the watermark portion or the non-watermark portion. An image forming apparatus characterized in that it is produced by either one of the above. In the image forming apparatus according to claim 6 or 7.
The watermark image is used as the watermark portion and the non-watermark portion in a state where the information sequence is flipped horizontally or vertically so that the information sequence is visually recognized in a normal arrangement state when the medium is viewed through from the back side. An image forming apparatus characterized in that it is produced. In the image forming apparatus according to claim 1,
An image forming apparatus comprising: a step processing means for processing so as to reduce or shield a step at a boundary between the watermark portion and the non-watermark portion constituting the watermark image. In the image forming apparatus according to claim 9,
The step processing means is an image forming apparatus characterized in that the amount of heat of fixing of the fixing means for fixing an image produced on the medium is increased from a normal fixing condition. In the image forming apparatus according to claim 9,
The step processing means is at least the transparent image forming means among the transparent image forming means and the similar color image forming means so as to reduce the step at the boundary between the watermark portion and the non-watermark portion constituting the watermark image. An image forming apparatus characterized by performing additional printing by. In the image forming apparatus according to claim 9,
The image forming apparatus is characterized in that the step processing means performs additional printing by the colored image forming means so as to shield the step at the boundary between the watermark portion and the non-watermark portion constituting the watermark image. In the image forming apparatus according to claim 1,
The image forming apparatus is characterized in that the selection means is selected when an image is produced on the medium in a security mode. In the image forming apparatus according to claim 1,
The designating means is an image forming apparatus characterized in that when the selection means selects to produce the watermark image, the production area and the production mode of the watermark image are automatically designated. In the image forming apparatus according to claim 1 or 14.
The designating means is an image forming apparatus characterized in that when the selection means selects to produce the watermark image, the production area and the production mode of the watermark image are variably designated. As a watermark image created in a predetermined designated area on the surface of a transparent medium, a watermark portion created according to a designated style using an image-forming agent having a color similar to that of the medium, and a transparent image-forming agent are used. An image structure having a non-watermark portion produced according to a designated format, and enabling the shadow of only the watermark portion of the watermark image to be visually recognized when viewed through the back side of the medium.

Images