JP2017128058A - Image formation apparatus and information protection method of used intermediate transfer foil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preventing unauthorized use such as diversion of a portion of personal information left on an intermediate transfer foil side or an OVD layer provided for prevention of falsification or interpolation quickly in an apparatus without requiring special post-processing when a transfer malfunction occurs in image transfer from the intermediate transfer foil to a transfer object body.SOLUTION: An image formation apparatus 1 includes a secondary transfer failure detection unit 40 which detects whether a transfer failure portion due to a secondary transfer malfunction is left on an intermediate transfer foil 10 after the secondary transfer process. When the transfer failure portion is left, the image formation apparatus transfers and forms one or more ink layers so as to cover the whole screen to be transferred with a sensor mark contained to a screen where transfer failure of the intermediate transfer foil occurs.SELECTED DRAWING: Figure 1

Description

  The present invention uses an ink ribbon and an intermediate transfer foil to form an image on the transfer layer of the intermediate transfer foil by the thermal transfer method, and then transfers the image formed on the transfer layer onto the transfer material together with the transfer layer. An image forming apparatus that performs image formation by transferring, and in the event that a transfer failure occurs when an image is transferred from the intermediate transfer foil onto the transfer target, the information remaining on the intermediate transfer foil is made unreadable The present invention relates to a processing method for preventing diversion of an intermediate transfer foil.

  The image forming method using the intermediate transfer foil performs printing on the intermediate transfer foil at the time of image formation even when the substrate of the transfer target on which the image is finally provided is different, such as paper or plastic. Therefore, since the object to be printed is constant and stable image formation is possible, it has been studied as one of image forming means using an ink ribbon.

  For example, a method of forming an image by thermal head printing using an ink ribbon is already a well-known technique, and is used for various purposes such as printing on a card, printing of a photographic image, printing on a seal, and the like. . However, many of these printing methods have a problem in that a specific image receiving layer needs to be provided on the surface of the medium, and combinations thereof are limited.

  Therefore, an ink ribbon is used to form an image on an intermediate transfer foil having a specific image receiving layer (transfer layer), and then secondary transfer to a transfer target, so that the substrate of the final printing medium can be selected. An intermediate transfer method has been proposed as a method capable of forming a multicolor image (see, for example, Patent Document 1).

  The intermediate transfer method has been used mainly as a means for forming a multicolor image on different substrates such as a passport and an ID (Identification) card. However, passports and ID cards are often required to be used for a relatively long period of 5 to 10 years, and high durability is required. For this reason, a technique using a hot-melt ink ribbon using a pigment, instead of using a sublimable dye as the ink ribbon, has been proposed (for example, Patent Document 2).

Also, personal authentication media such as passports and ID cards are required to have high resistance against fraudulent acts such as forgery and tampering.
Therefore, even in an image forming method using an intermediate transfer method, a method of imparting high anti-counterfeit / tampering properties by providing an OVD (Optical Variable Device) layer such as a hologram in the intermediate transfer foil is used.

  On the other hand, in the image forming method using the ink ribbon, personal information remains as negative information on the ink ribbon side after the image is formed. Therefore, when the used ink ribbon is discarded, personal information protection is performed. From the point of view, certain management has been required for the storage method and processing method of the used ink ribbon.

  On the other hand, a method of making negative information left on the ink ribbon side unreadable has been proposed (for example, Patent Document 3). However, in the intermediate transfer method, in addition to the information remaining on the ink ribbon side, when transferring an image from the intermediate transfer foil to the transfer target, due to the influence of dirt or dust on the transfer target surface, image transfer failure As a result, a part of the personal information may be left on the intermediate transfer foil side, or a part of the OVD layer such as a hologram provided for preventing forgery or falsification may be left. .

Japanese Patent Laid-Open No. 4-72046 Japanese Patent Laid-Open No. 10-58728 Japanese Patent No. 4207682

  With respect to these problems, the present invention does not require any special post-processing when an image transfer from the intermediate transfer foil to the transfer object occurs, and the intermediate transfer foil side can be quickly used in the apparatus. It is intended to provide a method for preventing illegal use such as diversion of a part of personal information left in or an OVD layer provided to prevent forgery or tampering.

The present invention has been made to solve the above problems.
That is, according to the first aspect of the present invention, an intermediate transfer foil having a transfer layer on a substrate is disposed opposite to an ink ribbon formed by arranging a plurality of color ink layer regions in a predetermined order on a substrate. Then, a first heating unit composed of a thermal head that forms an image on the intermediate transfer foil and a transfer target are superimposed on the intermediate transfer foil on which the image is formed, and two images are transferred to the transfer target. An image forming apparatus having a second heating unit for subsequent transfer, wherein the intermediate transfer foil is provided with a transfer failure detecting unit for detecting a secondary transfer defective portion. .

  Next, the invention according to claim 2 is such that an intermediate transfer foil having a transfer layer on the substrate is opposed to an ink ribbon having a plurality of color ink layer regions arranged in a predetermined order on the substrate. Arranging and heating using a first heating unit comprising a thermal head to transfer each ink layer to a predetermined position of the transfer layer to form an image; and A process of superimposing a transfer medium on the intermediate transfer foil and forming a second transfer image on the transfer medium by a second heating unit to form an image; and a secondary transfer failure area on the intermediate transfer foil The intermediate transfer foil is rewound, and at least the secondary transfer defective part is covered in the first heating part. Used to transfer and form one or more ink layers The information protection method of the intermediate transfer foil.

  According to a third aspect of the present invention, there is provided a sensor mark at a position where the intermediate transfer foil is not transferred to the transfer target for every one screen, and the intermediate transfer foil has a secondary transfer defect. 3. The used intermediate according to claim 2, wherein one or more ink layers are transferred and formed so as to cover the entire area of one screen to be transferred to the transfer object, including the sensor mark. This is an information protection method for a transfer foil.

  According to a fourth aspect of the present invention, there is provided an ink layer that is transferred and formed on the intermediate transfer foil so as to cover at least a secondary transfer failure occurrence portion when a secondary transfer failure to the transfer target occurs. The method for protecting information on a used intermediate transfer foil according to claim 2 or 3, comprising ink and comprising one or more ink layers.

  According to the present invention, in an indirect transfer method using an intermediate transfer foil in an image forming method using a thermal transfer method, when an image formed on the intermediate transfer foil is secondarily transferred to a transfer target, for some reason. In the case where a part of the image or OVD or the like is left on the intermediate transfer foil, it is possible to prevent information leakage or misuse of the forgery prevention element.

1 is a conceptual diagram illustrating an example of an image forming apparatus of the present invention. It is a flowchart which shows an example of the information protection method of the used intermediate transfer foil of this invention. It is a top view which shows an example of the image formed on the intermediate transfer foil. (A) It is a top view which shows an example of the mirror image formed on intermediate transfer foil. (B) It is a top view which shows the example in which the mirror image shown to (a) was normally transcribe | transferred to the to-be-transferred body. (C) It is a top view which shows the example in which the mirror image shown to (a) was not normally transferred to a to-be-transferred body. FIG. 6 is a plan view illustrating an example of a transfer target that is finally formed with an image. It is a top view which shows the example which has the sensor mark of the intermediate transfer foil in which the malfunction occurred in the secondary transfer. It is a top view which shows the example which formed the ink layer with respect to the malfunctioning intermediate transfer foil which has a sensor mark. It is a top view which shows an example of an ink ribbon. It is sectional drawing which shows an example of the intermediate transfer foil by which the image was formed. It is sectional drawing which shows the example which formed the ink layer in the malfunctioning intermediate transfer foil.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. However, it will be apparent that one or more embodiments may be practiced without such specific details. In addition, in order to simplify the drawings, descriptions of well-known structures and devices are omitted.

  Note that, throughout all the drawings, the same reference numerals are given to components that exhibit the same or similar functions, and redundant descriptions are omitted.

  FIG. 1 shows a schematic diagram of an image forming apparatus 1 of the present invention. The present invention is intended for image formation by the indirect transfer method using the intermediate transfer foil 10.

  That is, the intermediate transfer foil 10 and the ink ribbon 20 are placed opposite to each other, a mirror image is formed on the transfer layer 12 of the intermediate transfer foil 10 using the first heating unit (thermal head) 50, and then the intermediate transfer foil winding is performed. While the intermediate transfer foil 10 is being wound by the take-up portion 10b, the image formed by the previous thermal head 50 is transferred from the intermediate transfer foil 10 to the transfer target 30 by the second heating portion (heat roll) 60. This is an image forming method in which the final transfer is performed after the next transfer.

  Here, after the secondary transfer by the heat roll 60, a secondary transfer defect detection unit 40 is provided for detecting whether the secondary transfer from the intermediate transfer foil 10 to the transfer target 30 has been carried out reliably. .

  This secondary transfer failure detection unit 40 can detect whether or not a secondary transfer failure has occurred due to the influence of dirt or dust on the surface of the transfer target 30.

  Here, as a detection device to be used, any device such as a line sensor or an imaging camera may be used. Further, as a detection target, not only the image portion 16 formed by the thermal head 50 but also a hologram or a diffraction grating OVD (Optical Variable Device) layer on the intermediate transfer foil 10, special printing whose color changes depending on the angle, When fluorescent materials are provided, it is desirable that these images can also be detected, and the wavelength range and arrangement position of illumination light required for detection by a line sensor or imaging camera are set according to the purpose. can do.

  Further, it is desirable that the secondary transfer failure detection unit 40 can detect whether or not a secondary transfer failure has occurred in the entire printing area 15. However, the entire print area 15 is not necessarily secondarily transferred to the transfer target 30, and an unprinted portion does not occur when final image formation is performed on the transfer target 30. As described above, the print area 15 may be set slightly larger than the image forming area on the transfer target 30.

  FIG. 2 is a flowchart showing an example of the information protection method for the used intermediate transfer foil of the present invention. In FIG. 2, the detailed description of the image forming unit by the first heating unit (thermal head) 50 is omitted, but a known method in the image forming method using the intermediate transfer foil is adopted as a whole. be able to. For example, a known method such as an image alignment method, a wrinkle generation prevention method, or an invisibility processing method for information remaining on the ink ribbon side can be employed. Can be used.

  In the information protection method for used intermediate transfer foil of the present invention, as shown in FIG. 2, when printing information is input to the image forming apparatus 1 side, first, the first heating unit (thermal head) 50 performs intermediate transfer. A mirror image is printed 101 on the foil 10.

  Thereafter, the intermediate transfer foil 10 is taken up by the intermediate transfer foil take-up unit 10 b, moves the printing region 15 to a position where the mirror image can be transferred to the transfer target 30, and a second heating unit (heat roll) 60. Thus, the image transfer 102 is performed on the transfer target 30.

  The intermediate transfer foil 10 is wound up by the intermediate transfer foil winding unit 10b at the same time as the secondary transfer is performed by the heat roll 60, and the secondary transfer failure detecting unit 40 determines whether there is a secondary transfer defective portion 103 or not. The determination is performed.

  As a result of the determination, if a secondary transfer failure has occurred, the printing area 15 where the secondary transfer failure has occurred on the intermediate transfer foil 10 is rewound 104 to the position of the first heating unit (thermal head) 50; At the same time, an output 105 indicates that a problem has occurred. As an output method at this time, the image forming apparatus 1 of the present invention is provided with a display unit (display or display lamp) and displayed, or output to a terminal such as a PC (Personal Computer) that controls the image forming apparatus 1. It is possible to arbitrarily set a method for performing the output or a method for performing output to both of them.

  The ink ribbon 20 is wound up by the ink ribbon winding unit 20b up to the print start position for the next screen without being rewound.

  Thereafter, the black ink Bk of the ink ribbon 20 is printed 107 by the thermal head 50 so as to cover at least the secondary transfer defect occurrence portion, and more preferably including the sensor mark 18 and the entire printing region 15.

  This makes it difficult to view confidential information such as personal information remaining on the intermediate transfer foil 10, and at the same time, ink ink Bk is provided on the entire surface even if the remaining portion such as the OVD layer is misused. Therefore, since it is clearly different from the genuine product, it is difficult to exploit it.

  Here, the ink printed so as to cover the entire printing area 15 is not necessarily limited to the black ink Bk. However, in the field of personal authentication media such as ID cards and passports such as identification cards, personal information such as name, ID number, date of birth, etc. is often printed with ink ink. In order to make it difficult, it is desirable to use ink of the same color tone. As an example of use other than the black ink Bk, a method of overprinting each color ink of cyan C, magenta M, and yellow Y can be used. Ink Bk, cyan C, magenta M, and yellow Y inks may be used alone or in combination of two or more colors. Furthermore, the pattern formed by the ink layer is not limited to a single-color solid pattern as long as it is difficult to visually recognize confidential information such as personal information, and any pattern can be arbitrarily set.

  As described above, after the black ink is printed on the secondary transfer failure occurrence portion of the intermediate transfer foil 10, the first heating portion (thermal head) until the position where a new mirror image is formed. The intermediate transfer foil 10 is taken up 108 and a mirror image having a secondary transfer failure is printed again based on the reprint instruction 109.

  The reprinting instruction 109 at this time may be automatically executed in the image forming apparatus 1 or may be automatically issued from a terminal side such as a PC that controls the image forming apparatus 1. Further, a method in which an instruction is issued by an operator who operates the image forming apparatus 1 may be used.

  Further, the timing at which the reprint instruction 109 is issued does not necessarily have to be immediately after the occurrence of the secondary transfer failure. After the information is recorded and held in the memory for storing the failure occurrence information and a new printing process is performed, The reprint instruction 109 may be issued at an arbitrary timing.

  The transferred object 30 finally formed with an image is inspected 106 by another inspection unit provided in the image forming apparatus 1 to determine whether or not there is a problem with the formed image. Outputs 105 that a problem has occurred and a reprint instruction 109 is issued. At this time, for the steps 105 and 109, the same method as described above can be used.

  Here, as a problem of the image formed on the transfer target 30 that cannot be detected by the secondary transfer failure detection unit 40, for example, when it occurs in the first heating unit 50, or to the intermediate transfer foil side at the time of secondary transfer Although no residual image remains, there is no problem with secondary transfer failure due to wrinkles or the like, or there is no problem with the first heating unit 50 or the second heating unit 60. There may be a case where the personal information recorded on the recording medium or the like does not match the printed image.

  However, with respect to the problem occurring in the first heating unit 50, if there is a problem after image inspection is performed after the mirror image printing 101 by the first heating unit, the transfer by the second heating unit is performed. It is desirable to shift to the step 104 without performing the image transfer 102 to the body 30. This is to reduce the loss of the expensive transfer target 30.

  The to-be-transferred body 30 in which any defect has occurred receives the information from the secondary transfer failure detection unit 40 or the information from the image inspection unit provided separately, and the secondary transfer is normally performed. It is preferable that the data is output to another output unit different from the output unit of the transfer target and is not mixed.

  When the secondary transfer failure detection unit 40 determines that a secondary transfer failure has not occurred, the secondary transfer failure detection unit 40 outputs the transferred image as a transfer target 30 on which secondary transfer has been normally performed, and is based on the next input information. Output work is performed.

  Further, when the power is turned off while the image forming apparatus 1 is in operation for some reason, the same operation procedure as the process shown in FIG. 2 is performed when the image forming apparatus 1 is turned on. Initialization operation (initialization) is performed.

  FIG. 3 is a diagram schematically showing an example of the mirror image formed on the intermediate transfer foil 10 and the intermediate transfer foil after the secondary transfer.

  FIG. 3A shows an example in which a mirror image is formed on the intermediate transfer foil 10, and FIG. 3B shows that the mirror image formed in FIG. It is the figure which showed the state of the intermediate transfer foil 10 after being done.

  Here, a part of the printing area 15 remains even after the secondary transfer to the transfer target 30. This is generally the case when image formation using an intermediate transfer foil is performed on an ID card or the like. In some cases, an unprinted portion such as a border portion is not set on the card surface, and the entire surface may be printed. Therefore, in order to prevent the occurrence of an unprinted portion due to misalignment during secondary transfer, This is because the print region 15 is set with an area slightly larger than the area.

  FIG. 3B shows a state in which the secondary transfer defective portion is not left in the secondary transfer region 17, and an example of the transfer target 30 that has been secondarily transferred is shown in FIG. 4.

  FIG. 3C shows an example in which a defect occurs in the secondary transfer. In this example, a part of the printed image remains on the intermediate transfer foil 10 side without being secondarily transferred to the transfer body 30 due to the influence of the surface contamination of the transfer body 30. As shown in FIG. 3C, when a part of the personal information is left on the intermediate transfer foil 10 side and discarded as it is, there is a possibility that it is misused by a malicious third party.

  FIG. 5 shows an intermediate transfer foil 10 provided with a sensor mark portion 18 that is used for specifying a position when a mirror image is formed on the intermediate transfer foil 10 or when the obtained mirror image is secondarily transferred to the transfer target 30. Fig. 2 shows an example in which a secondary transfer failure occurs.

  As shown in FIG. 5, in the case of the intermediate transfer foil 10 having the sensor mark portion 18, if it is discharged outside by disposal or the like while including a portion not subjected to the secondary transfer, it is illegal to use a similar image forming apparatus. May be issued a personal authentication medium.

  In order to avoid such a risk, as shown in FIG. 6, the black ink Bk covers the entire printing area 15 including the sensor mark portion 18 used for specifying the position by the image forming apparatus 1. It is desirable to form an ink layer.

  This makes it difficult to read the sensor mark by the image forming apparatus, and even when the similar image forming apparatus is abused, the secondary transfer operation can be disabled.

  In FIGS. 5 and 6, an alternate long and short dash line is drawn on the periphery of the print region 15 and a broken line is drawn on the periphery of the sensor mark portion 18, but these lines actually exist. It is drawn for convenience in order to clarify the positional relationship.

  FIG. 7 is a view showing an example of the ink ribbon 20 used in the image forming apparatus 1 of the present invention. Each ink region of black ink Bk, cyan ink C, magenta ink M, yellow ink Y, and primer ink P is sequentially provided on the base material.

  As the ink ribbon used in the present invention, a sublimation transfer type ink ribbon using a sublimation dye and a heat melting type ink ribbon using a pigment are conceivable.

  In personal authentication media such as passports and ID cards, it may be assumed to be used for a long period of 5 to 10 years. Considering the durability of the printed image formed, a hot-melt ink ribbon using a pigment is used. Is more desirable.

When a hot-melt ink ribbon is used, various known pigments can be used as the pigment used in each ink layer, such as carbon black, azo, phthalocyanine, quinacridone, thioindigo, and anthraquinone. And isoindolinone pigments. These may be used in combination of two or more, and a known dye may be added for hue adjustment.

  Examples of the binder resin for each ink layer having these coloring materials include butyral resin, polyamide resin, polyethyleneimine resin, sulfonamide resin, polyester polyol resin, petroleum resin, epoxy resin, styrene resin, styrene and its derivatives, methyl Methacrylic acid esters such as methacrylate, ethyl methacrylate, hydroxy methacrylate, hydroxyethyl methacrylate, etc. and acrylic acid esters such as methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, vinyl monomers such as vinyl chloride and vinyl acetate alone or A copolymer or the like can be used. These resins can be used in combination of two or more.

  In addition to the pigment and the binder resin, additives such as a release agent, a softening agent, and a surfactant can be appropriately added to each color ink layer.

  Examples of the base material of the ink ribbon 20 formed in this way include paper such as capacitor paper, polyester film, polystyrene, polycarbonate, acrylic, polypropylene film, cellophane, and the like, and particularly heat resistance and easy handling. Considering the properties, a polyester film is preferable, and specifically, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), and the like are preferable. The thickness of the substrate is preferably 2 to 50 μm, more preferably 2 to 16 μm, from the viewpoint of mechanical strength, ease of handling, and availability.

  Further, the substrate can be provided with a backcoat layer on the side opposite to the respective color ink layers as necessary. The backcoat layer is a layer that is in close contact with the heat source of the thermal head 50, and is mainly Although heat resistance and slipperiness are required, an acrylic resin, a urethane resin, an acrylic silicone resin, a urethane silicone resin, or a known material obtained by adding silicone oil, wax, fats and oils, or the like to these can be appropriately selected.

  Here, after forming a mirror image on the intermediate transfer foil 10, the primer ink P is subjected to secondary transfer on the transfer target 30, and the material and surface of the transfer target 3 depending on the application and user's request. This is for obtaining stable characteristics of the final printed matter because the processing situation may be different.

  As the resin used for the primer ink P, for example, butyral resin, polyamide resin, polyethyleneimine resin, sulfonamide resin, polyester polyol resin, petroleum resin, epoxy resin, styrene resin, styrene, and the like, as with each color ink Derivatives, methacrylic esters such as methyl methacrylate, ethyl methacrylate, hydroxy methacrylate, hydroxyethyl methacrylate, etc., and acrylic monomers such as methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, vinyl monomers such as vinyl chloride and vinyl acetate These can be used alone or as a copolymer. These resins can be used in combination of two or more. In addition, additives such as various fillers may be added as appropriate.

  FIG. 8 is a cross-sectional view illustrating an example of the intermediate transfer foil 10 after the first heating unit 50 forms an image.

Here, the intermediate transfer foil 10 includes a substrate 11 and a transfer layer 12 as shown in FIG.

  The base material 11 of the intermediate transfer foil 10 is preferably PET or PEN as in the case of the base material of the ink ribbon 20, and the thickness thereof is not particularly limited. In consideration of formation of a multicolor image by the thermal head 50 and heating with a hot roll at the time of transfer to a transfer target, the thickness is more preferably 12 to 100 μm.

  The transfer layer 12 is a thermoplastic resin, a styrene resin such as polystyrene or poly-α-methylstyrene, an acrylic resin such as polymethyl methacrylate or polyethyl acrylate, polyvinyl chloride, polyethyl acetate, vinyl chloride-acetic acid. Synthetic resins such as vinyl copolymers, vinyl resins such as polyvinyl petital and polyvinyl acetal, polyester resins, polyamide resins, epoxy resins, polyurethane resins, petroleum resins, ethylene acrylic copolymers, and ethylene-acrylic ester copolymers One or two or more thermoplastic resins such as rosin, styrene butadiene rubber, butyl rubber, butadiene acrylonitrile rubber, polychlorinated olefin, and cellulose derivative can be used as a main component.

  Moreover, there is no problem even if the intermediate transfer foil 10 is provided with a release layer, an anchor layer, a printing layer, an OVD layer, etc. as other layers.

  FIG. 9 is a cross-sectional view showing an example in which an ink layer is provided in the intermediate transfer foil 10 when a failure in secondary transfer occurs. Here, an example is shown in which an ink layer is transferred and formed on the remaining image portion that has not been secondarily transferred.

  As shown in FIG. 9, a new ink layer is formed so as to cover the printing portion 16 remaining without being secondarily transferred, and to cover the primer layer provided for improving the adhesion to the transfer target 30. (Ink ink Bk in FIG. 9) is formed.

  As a result, it becomes difficult to visually recognize the information that remains without being secondarily transferred, and at the same time, when a malicious third party obtains a used intermediate transfer foil that is discarded, Since the primer layer that improves the adhesion to the transfer target 30 is covered, sufficient adhesion cannot be obtained, and it becomes difficult to create a counterfeit product.

  Further, even if it can be adhered to the transfer medium by some method, it is recognized that the black ink layer Bk is formed so as to cover the entire printing portion 16 and is not genuine at first glance. be able to.

  From the above, by taking the information protection method of the used intermediate transfer foil of the present invention, the disposal of the used intermediate transfer foil does not require a troublesome work, and the information protection processing is performed in the printing apparatus. Simple disposal work becomes possible.

DESCRIPTION OF SYMBOLS 10 ... Intermediate transfer foil 10a ... Intermediate transfer foil winding part 10b ... Intermediate transfer foil winding part 11 ... Base material 12 ... Transfer layer 15 ... Print area 16 ... Print part 17 ... Secondary transfer area 18 ... Sensor mark part 20 ... Ink ribbon 20a ... Ink ribbon unwinding section 20b ... Ink ribbon winding section Bk ... Black ink C ... Cyan ink M ... Magenta ink Y ... Yellow ink P ... Primer ink 30 ... Transfer target 40 ... Secondary transfer failure detection section 50 ... 1st heating part (thermal head)
60 ... 2nd heating part (heat roll)

Claims (4)

An intermediate transfer foil having a transfer layer on the substrate is disposed opposite to an ink ribbon in which a plurality of color ink layer regions are arranged in a predetermined order on the substrate, and an image is formed on the intermediate transfer foil. A first heating unit comprising a thermal head;
An image forming apparatus including a second heating unit that superimposes a transfer target on the intermediate transfer foil on which an image is formed, and secondarily transfers the image to the transfer target;
An image forming apparatus comprising a transfer failure detection unit for detecting a secondary transfer failure portion on the intermediate transfer foil. First heating comprising a thermal head by placing an intermediate transfer foil having a transfer layer on a substrate opposite to an ink ribbon formed by arranging a plurality of color ink layer regions in a predetermined order on a substrate. Forming the image by transferring each ink layer to a predetermined position of the transfer layer by heating using a portion; and
A step of superimposing a transfer medium on the intermediate transfer foil on which an image has been formed, and performing a secondary transfer on the transfer medium by a second heating unit to form an image;
Detecting whether or not there is a secondary transfer failure portion on the intermediate transfer foil,
When there is a secondary transfer defective portion, the intermediate transfer foil is rewound, and one or more ink layers are transferred and formed in the first heating portion so as to cover at least the secondary transfer defective portion. A method for protecting information on a used intermediate transfer foil.   A sensor mark is provided at a position where the intermediate transfer foil is not transferred to the transfer target for each screen, and the intermediate transfer foil including the sensor mark is provided for the intermediate transfer foil in which a secondary transfer failure has occurred. The method for protecting information on a used intermediate transfer foil according to claim 2, wherein one or more ink layers are transferred and formed so as to cover the entire area of one screen to be transferred to the transfer body.   An ink layer transferred and formed on the intermediate transfer foil so as to cover at least a secondary transfer failure occurrence portion when at least a secondary transfer failure to the transfer object occurs includes at least black ink and one or more inks The method for protecting information on a used intermediate transfer foil according to claim 2 or 3, comprising a layer.