Image recording medium, method of producing image recording medium, and image forming apparatus

An image recording medium includes two sheets made of resin and a toner image interposed between the two sheets. The toner image serves as an adhesive to bond the two sheets together and includes an information image. At least one of the two sheets includes a transparent portion to enable the information image to be visible through the at least one of the two sheets.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application No. 2018-203911, filed on Oct. 30, 2018, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.

BACKGROUND

Technical Field

Embodiments of the present disclosure generally relate to an image recording medium produced by bonding two sheets, a method of producing the image recording medium, and an image forming apparatus.

Description of the Related Art

There is a technique to produce an image recording medium (recording medium) by bonding two sheets with toner serving as an adhesive using an image forming apparatus such as an electrophotographic color printer.

SUMMARY

Embodiments of the present disclosure describe an improved image recording medium that includes two sheets made of resin and a toner image interposed between the two sheets. The toner image serves as an adhesive to bond the two sheets together and includes an information image. At least one of the two sheets includes a transparent portion to enable the information image to be visible through the at least one of the two sheets.

The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. In addition, identical or similar reference numerals designate identical or similar components throughout the several views.

DETAILED DESCRIPTION

Embodiments of the present disclosure are described in detail with reference to drawings. It is to be understood that identical or similar reference numerals are assigned to identical or corresponding components throughout the drawings, and redundant descriptions are omitted or simplified below as required.

It is to be noted that the suffixes Y, M, C, K, and S attached to each reference numeral indicate only that components indicated thereby are used for forming yellow, magenta, cyan, black, and special color images, respectively, and hereinafter may be omitted when color discrimination is not necessary.

With reference toFIGS. 1 and 2, a configuration and operation of an image forming apparatus100is described below.

FIG. 1is a schematic view illustrating a configuration of the image forming apparatus100, which in the present embodiment is a printer, for example.FIG. 2is an enlarged view of a process cartridge6Y and the vicinity thereof in the image forming apparatus100illustrated inFIG. 1.

The image forming apparatus100according to the present embodiment is used to form an image on a sheet P such as plain paper, and also produces an image recording medium PT in which two sheets P1and P2that are overlaid and bonded. Hereinafter, the operation of the image forming apparatus100when an image is formed on a sheet P such as plain paper is mainly described below before descriptions of the image recording medium PT.

As illustrated inFIG. 1, toner supply devices90Y,90M,90C,90K, and90S are arranged in parallel on one side of an upper portion of the image forming apparatus100. Five toner containers32Y,32M,32C,32K, and32S of different types are removably installed in the toner supply devices90Y,90M,90C,90K, and90S, respectively. The toner containers32Y,32M,32C,32K and32S are substantially cylindrical in the present embodiment. Specifically, as illustrated inFIG. 1, the toner containers32Y,32M,32C (and the toner supply devices90Y,90M, and90C) corresponding to three colors (yellow, magenta, and cyan) are disposed in order of yellow, magenta, and cyan from the left. The toner container32K (and the toner supply device90K) for black is disposed to the right of the toner container32C for cyan, with a toner container32S (and the toner supply device90S) for special color disposed on the far right, to the right of the toner container32K.

In particular, the toner container32S for special color is often replaced with a toner container32S for another type of special color depending on usage before all of the toner contained therein is consumed. Accordingly, the toner container32S is replaced more frequently than the other toner containers32Y,32M,32C, and32K are, and for this reason, the toner container32S is disposed farthest to the right to facilitate replacement.

With reference toFIGS. 1 and 2, the toner supply device90K for black supplies black toner contained in the toner container32K for black to the developing device5K for black.

In addition, the three toner supply devices90Y,90M, and90C for yellow, magenta, and cyan supply color toners of yellow, magenta, and cyan contained in the toner containers32Y,32M, and32C for colors to the developing devices5Y,5M, and5C for colors, respectively.

The toner supply device90S for special color supplies a special color toner contained in the toner container32S for special color to the developing device5S for special color.

Any toner can be used as the black toner; the color toner of each of yellow, magenta, and cyan; or the special color toner.

In particular, the special color toner is different from the black toner and the color toners, and any white toner, clear toner (transparent toner, colorless toner, achromatic toner, no-pigment toner, or the like), gold toner, silver toner, or the like can be used as the special color toner depending on usage.

With reference toFIG. 1, five exposure devices7Y,7M,7C,7K, and7S are disposed in an upper section of the image forming apparatus100, and process cartridges6Y,6M,6C,6K, and6S corresponding to yellow, magenta, cyan, black, and special color are arranged in parallel under the exposure devices7Y,7M,7C,7K, and7S, facing an intermediate transfer unit15including an intermediate transfer belt8.

As illustrated inFIG. 1, in the basic arrangement, the five process cartridges6Y,6M,6C,6K, and6S are disposed in the order of the process cartridge6S for special color, the process cartridge6Y for yellow, the process cartridge6M for magenta, the process cartridge6C for cyan, and the process cartridge6K for black from upstream in the direction of rotation of the intermediate transfer belt8(hereinafter, referred to as “rotation direction”). However, the arrangement order (arrangement) is appropriately varied depending on usage.

The special color toner is not limited to one type, and in many cases, different types of toner containers32S for special colors are replaced depending on usage as appropriate. For example, the toner container32S for clear toner may be replaced with the toner container32S for white toner.

In such a case, depending on the type of the special color toner, preferably the process cartridge6S for special color is moved from an extreme upstream installation position to an extreme downstream installation position in the rotation direction of the intermediate transfer belt8. For example, the clear toner as the special color toner is often used for improving the glossiness of an image, and it is desirable that the clear toner be primarily transferred onto the intermediate transfer belt8first. Accordingly, as illustrated inFIG. 1, the process cartridge6S for special color is disposed at the extreme upstream installation position in the rotation direction of the intermediate transfer belt8. On the other hand, the white toner as the special color toner is often used for forming an image on a colored sheet P that is not white, and it is desirable that the white toner be secondarily transferred in the lowermost layer on the sheet P. Accordingly, the process cartridge6S for special color is disposed at the extreme downstream installation position in the rotation direction of the intermediate transfer belt8. With the rearrangement of the installation position of the process cartridge6S for special color, the installation position of the process cartridge6K for black is replaced with the installation position of the process cartridge6S. Users or technicians manually perform the rearrangement operation according to procedures displayed on a control panel disposed on an exterior of the image forming apparatus100.

With reference toFIG. 2, the process cartridge6Y for yellow is a single unit removably installed in the image forming apparatus100, includes the photoconductor drum1Y, and further includes a charger4Y, the developing device5Y, and a cleaner2Y disposed around the photoconductor drum1Y. Image formation processes, namely, charging, exposure, development, transfer, and cleaning processes are performed on the photoconductor drum1Y, and thus a yellow toner image is formed on the photoconductor drum1Y.

Note that the other four process cartridges6M,6C,6K, and6S have a configuration similar to that of the process cartridge6Y for yellow except for the color of toner used therein, and form magenta, cyan, black, and special color toner images, respectively. Thus, for brevity, only the process cartridge6Y is described below and descriptions of the other four process cartridges6M,6C,6K, and6S are omitted.

With reference toFIG. 2, it is to be noted that the photoconductor drum1Y is rotated counterclockwise inFIG. 2by a drive motor. The charger4Y uniformly charges a surface of the photoconductor drum1Y at a position opposite the charger4Y (a charging process).

When the surface of the photoconductor drum1Y reaches a position where the surface of the photoconductor drum1Y is irradiated with a laser beam L emitted from the exposure device (writing device)7Y, the photoconductor drum1Y is scanned with the laser beam L, and thus an electrostatic latent image for yellow is formed on the surface of the photoconductor drum1Y (an exposure process).

Then, the photoconductor drum1Y reaches a position opposite the developing device5Y, where the electrostatic latent image is developed with toner into a yellow toner image (a development process).

When the surface of the photoconductor drum1Y carrying the toner image reaches a position opposite a primary transfer roller9Y via the intermediate transfer belt8, the toner image on the photoconductor drum1Y is transferred onto the intermediate transfer belt8(a primary transfer process). After the primary transfer process, a certain amount of untransferred toner remains on the photoconductor drum1Y.

When the surface of the photoconductor drum1Y reaches a position opposite the cleaner2Y, a cleaning blade2acollects the untransferred toner from the photoconductor drum1Y into the cleaner2Y (a cleaning process).

Subsequently, the surface of the photoconductor drum1Y reaches a position opposite a discharger, and the discharger removes residual potentials from the photoconductor drum1Y to complete a sequence of image formation processes performed on the photoconductor drum1Y.

The above-described image formation processes are performed in the process cartridges6M,6C,6K, and6S similarly to the process cartridge6Y for yellow. That is, the exposure devices7M,7C,7K, and7S disposed above the process cartridges6M,6C,6K, and6S irradiate respective photoconductor drums1M,1C,1K, and1S of the process cartridges6M,6C,6K, and6S with the laser beams L based on image data. Specifically, the exposure devices7Y,7M,7C,7K, and7S includes light sources to emit the laser beams L. The laser beams L are directed to the respective photoconductor drums1Y,1M,1C,1K, and1S via the multiple optical elements while being deflected by the polygon mirror that is rotated by a motor.

Then, the respective single-color toner images formed on the respective photoconductor drums1Y,1M,1C,1K, and1S through the development process are primarily transferred to and superimposed on the intermediate transfer belt8. Thus, a desired multicolor toner image is formed on the intermediate transfer belt8.

InFIG. 1, the intermediate transfer unit15includes the intermediate transfer belt8, the five primary transfer rollers9Y,9M,9C,9K, and9S (seeFIG. 2), a drive roller, a secondary transfer backup roller, multiple tension rollers, a cleaning backup roller, and a belt cleaner. The intermediate transfer belt8is supported by and entrained around multiple rollers to rotate in the direction indicated by arrow A1illustrated inFIG. 1(clockwise) as one (the drive roller) of the multiple rollers rotates.

The five primary transfer rollers9Y,9M,9C,9K and9S are pressed against the corresponding photoconductor drums1Y,1M,1C,1K, and1S, respectively, via the intermediate transfer belt8to form primary transfer nips. A transfer voltage (primary transfer bias) opposite in polarity to the toner is applied to each of the primary transfer rollers9Y,9M,9C,9K, and9S.

The intermediate transfer belt8rotates in the direction indicated by arrow A1inFIG. 1and sequentially passes through the primary transfer nips of the primary transfer rollers9Y,9M,9C,9K, and9S. Then, the single-color toner images on the photoconductor drums1Y,1M,1C,1K, and1S are primarily transferred to and superimposed on the intermediate transfer belt8.

Subsequently, the intermediate transfer belt8carrying the multicolor toner image reaches a position opposite the secondary transfer roller19. At this position, the secondary transfer backup roller and the secondary transfer roller19press against each other via the intermediate transfer belt8, thereby forming a secondary transfer nip where images are formed on sheets P. The multicolor toner image on the intermediate transfer belt8is transferred onto a sheet P such as paper transported to the secondary transfer nip (a secondary transfer process). At that time, toner that is not transferred onto the sheet P remains on the surface of the intermediate transfer belt8.

The surface of the intermediate transfer belt8reaches a position opposite the belt cleaner. At this position, the belt cleaner collects the untransferred toner remaining on the intermediate transfer belt8to complete a series of image transfer processes performed on the intermediate transfer belt8.

As described above, the process cartridges6Y,6M,6C,6K, and6S, the exposure devices7Y,7M,7C,7K, and7S, the intermediate transfer unit15, the secondary transfer roller19, and the like function as an image formation device to form toner images on the sheets P.

With reference toFIG. 1, the sheet P is transported from a sheet feeding unit (sheet tray)26disposed in a lower portion of the image forming apparatus100to the secondary transfer nip where images are formed on sheets P, through a sheet feeding path K1along which a sheet feeding roller27and a registration roller pair28are disposed.

Specifically, the sheet feeding unit26contains a stack of multiple sheets P. As the sheet feeding roller27rotates counterclockwise inFIG. 1, the sheet feeding roller27feeds a top sheet P from the stack in the sheet feeding unit26to a roller nip between the registration roller pair28.

The registration roller pair (timing roller pair)28temporarily stops rotating, stopping the sheet P with a leading edge of the sheet P nipped between the registration roller pair28. The registration roller pair28rotates to transport the sheet P to the secondary transfer nip, timed to coincide with the arrival of the multicolor toner image on the intermediate transfer belt8. Thus, the desired multicolor toner image is transferred onto the sheet P.

Subsequently, the sheet P, onto which the multicolor image is transferred at the secondary transfer nip, is transported to a fixing device20. In the fixing device20, a fixing belt and a pressing roller apply heat and pressure to the sheet P to fix the multicolor toner image on the sheet P (a fixing process).

The sheet P is transported through an ejection path K2and ejected by an output roller pair to the outside of the image forming apparatus100. The sheets P ejected by the output roller pair are sequentially stacked as output images on a stack tray, thus completing a sequence of image formation processes in single-side printing performed in the image forming apparatus100.

With reference toFIG. 1, in single-side printing, the sheet P is ejected from the image forming apparatus100after the toner image is fixed on the front side of the sheet P. By contrast, in duplex printing to form toner images on both sides (front side and back side) of the sheet P, the sheet P after the fixing process of the front side is guided to a reverse path K3by a switching pawl. After a direction of conveyance of the sheet P is reversed in the reverse path K3, the sheet P is guided to a duplex-printing path K4. Subsequently, the sheet P guided to the duplex-printing path K4is again transported to the secondary transfer nip where images are formed on the sheet P. Then, through the image formation processes (image forming operations) similar to those described above, the toner image is transferred onto the back side of the sheet P at the secondary transfer nip and fixed thereon by the fixing device20, after which the sheet P is ejected from the image forming apparatus100via the ejection path K2.

Next, a configuration and operation of the developing device5Y of the process cartridge6Y are described in further detail below with reference toFIG. 2.

A casing of the developing device5Y to contain developer G is divided, at least partially, into two developer-containing compartments. The developing device5Y includes a developing roller51opposed to the photoconductor drum1Y, a doctor blade52opposed to the developing roller51, two conveying screws55respectively disposed in the developer-containing compartments, a density sensor56to detect a concentration (percentage) of toner in the developer G or toner density, and an opening57to supply toner to the developer-containing compartment. The developing roller51includes stationary magnets, a sleeve that rotates around the magnets, and the like. The developer-containing compartment contains the two-component developer G including carrier and toner.

The developing device5Y operates as follows.

The sleeve of the developing roller51rotates in the direction indicated by arrow A2inFIG. 2. The developer G is carried on the developing roller51by a magnetic field generated by the magnets. As the sleeve rotates, the developer G moves along a circumference of the developing roller51.

The percentage (concentration) of toner in the developer G (ratio of toner to carrier) in the developing device5Y is adjusted within a predetermined range. More specifically, the toner supply device90Y supplies toner from the toner container32Y to the developing device5Y through a toner conveyance path98as the toner in the developing device5Y is consumed.

While being stirred and mixed with the developer G by the two conveying screws55in the developing device5Y (or the developer-containing compartments), the supplied toner is circulated between the two developer-containing compartments, which are separated by a partition wall, in a longitudinal direction of the developing device5Y. The longitudinal direction of the developing device5Y is perpendicular to the surface of the paper on whichFIG. 2is drawn. The toner in the two-component developer G is triboelectrically charged by friction with the carrier and electrostatically attracted to the carrier. Then, the toner is carried on the developing roller51together with the carrier by the magnetic force generated on the developing roller51.

The developer G carried on the developing roller51is transported along an outer circumference of the sleeve in the clockwise direction indicated by arrow A2inFIG. 2to the doctor blade52. The amount of developer G on the developing roller51is adjusted by the doctor blade52, after which the developer G is carried to a development range opposed to the photoconductor drum1Y. The toner in the developer G is attracted to the electrostatic latent image formed on the photoconductor drum1Y due to the effect of an electric field generated in the development range. As the sleeve rotates, the developer G remaining on the developing roller51reaches an upper part of the developer-containing compartment, drops from the developing roller51, and returns to the developer-containing compartment.

Next, with reference toFIGS. 3A to 5C, image recording media PT according to the present embodiments are described below.

An image recording medium PT illustrated inFIG. 3Bis a composite sheet that includes two sheets P1and P2, and a toner image (information image X1) interposed between the two sheets P1and P2. The toner image (information image X1) serves as an adhesive to bond the two sheet P1and P2overlaid on each other.

According to the image recording medium PT of the present embodiment, the two sheets P1and P2are both made of resin, and a transparent portion is provided to enable the toner image (information image X1) to be visible through at least one of the two sheets P1and P2. In other words, the two sheets P1and P2are made of a water-resistant material, and the at least one of the two sheets P1and P2has the transparent portion to enable the toner image (information image X1) to be visible.

Note that the “transparent portion” (or the term “transparent” as used herein) can have a transparency (or transparent state) that is sufficient to allow an image on the opposite side of the transparent portion to be visible, and need not necessarily be 100% transparent.

Specifically, in the present embodiment, the two sheets included in the image recording medium PT are both transparent resin sheets (i.e., a first transparent resin sheet P1and a second transparent resin sheet P2). Hereinafter, the first and second transparent resin sheets P1and P2are also simply referred to as “two sheets P1and P2” or “two transparent resin sheets P1and P2”. That is, both sheets P1and P2are entirely transparent. The two transparent resin sheets P1and P2are made of a water-resistant transparent resin material such as polyethylene terephthalate (PET).

More specifically, as illustrated inFIG. 3A, the information image X1(toner image) intended by a user is formed on almost the entire surface of the first transparent resin sheet P1. The information image X1(toner image) is formed in single color or mixed multiple colors of yellow, magenta, cyan, black, and/or a special color. In the example ofFIG. 3A, the letter “R” is formed at the center of the surface of the first transparent resin sheet P1, and the other portion is formed in a different color. Then, the second transparent resin sheet P2, on which no image is formed, is overlaid on the first transparent resin sheet P1so that the information image X1formed on the surface (front surface) of the first transparent resin sheet P1is interposed between the two sheets P1and P2. At that time, pressure and heat (or only pressure) are applied to the two transparent resin sheets P1and P2that are overlaid, thereby producing the image recording medium PT illustrated inFIG. 3Bby the information image X1(toner image) serving as the adhesive.

In the image recording medium PT produced as described above, the information image X1formed on the first transparent resin sheet P1is visible in the direction indicated by the white arrow inFIG. 3Bwith the second transparent resin sheet P2as the front side.

On the other hand, in the example ofFIG. 4A, the inverted letter “R” (i.e., a mirror image of the image intended by a user) is formed at the center of the surface of the first transparent resin sheet P1, and the other portion is formed in different color. Then, the second transparent resin sheet P2is overlaid on the first transparent resin sheet P1so that the information image X1formed on the surface (front surface) of the first transparent resin sheet P1is interposed between the two sheets P1and P2, and pressure and heat are applied to the two transparent resin sheets P1and P2, thereby producing an image recording medium PT illustrated inFIG. 4B.

In the image recording medium PT produced as described above, the information image X1formed on the first transparent resin sheet P1is visible in the direction indicated by the white arrow inFIG. 4Bwith the first transparent resin sheet P1as the front side.

As described above, the image recording medium PT according to the present embodiment includes the two sheets P1and P2that are overlaid and bonded by the toner image as the adhesive. Accordingly, there are fewer restrictions, and the image recording medium PT is inexpensive and convenient and can be easily produced as compared with the case in which a different adhesive is used separately.

In addition, since the image recording medium PT according to the present embodiment is formed by bonding two transparent resin sheets P1and P2together, the image recording medium PT has high water resistance and high durability and is less likely to be scratched as compared with an image recording medium using plain paper. In addition, the image recording medium PT according to the present embodiment is formed by bonding two transparent resin sheets P1and P2made of the same material together. Accordingly, the degrees of expansion and contraction of the two sheets due to environmental changes are equivalent, and the image recording medium PT is less likely to curl as compared with a case in which two sheets made of different materials are bonded together.

Therefore, the image recording medium PT according to the present embodiment is suitable as a medium, on which information is recorded, used in a wet environment, an environment in which durability is required, or a fluctuating environment.

In the present embodiment, the information image X1is formed over almost the entire surface between the two sheets P1and P2, and the two sheets P1and P2are bonded by the information image X1(toner image) as the adhesive to form the image recording medium PT. However, an area of the toner image as the adhesive interposed between the two sheets P1and P2is not limited to the entire surface. For example, a toner image as the adhesive can be interposed only along the edges of the surface of the two sheets P1and P2with a substantially annular shape, and the central portion of the surface of the two sheets P1and P2can be seen through without a toner image interposed in the central portion. In such a case, the toner image serving as the adhesive may be a single color or multiple colors.

Here, in the present embodiment, the image recording medium PT is produced by the image forming apparatus100described above with reference toFIGS. 1 and 2. When an image recording medium PT is produced, the “special print mode” is selected by the control panel instead of the normal printing operations (image forming operations) described with reference toFIGS. 1 and 2.

Hereinafter, descriptions are provided of a method of producing the image recording medium PT and the image forming apparatus100to produce the image recording medium PT.

As described above with reference toFIGS. 3 and 4, in the image recording medium PT, the toner image (information image X1) is interposed between the first transparent resin sheet P1and the second transparent resin sheet P2. The first transparent resin sheet P1and the second transparent resin sheet P2are overlaid and bonded by the toner image (information image X1) serving as the adhesive.

Such a method of producing the image recording medium PT is roughly classified into an image forming process, a fixing process, and an adhesion process.

The image forming process is a process of forming a toner image on the front surface of the first transparent resin sheet P1and performed by the image forming device of the image forming apparatus100including: the process cartridges6Y,6M,6C,6K, and6S; the exposure devices7Y,7M,7C,7K, and7S; the intermediate transfer unit15; and secondary transfer roller19.

The fixing process is a process of applying pressure and heat to the toner image formed on the front surface of the first transparent resin sheet P1in the image forming process to fix the toner image on the front surface and performed by the fixing device20.

The adhesion process is a process of applying pressure, or pressure and heat to the two sheets P1and P2overlaid to bond the first transparent resin sheet P1and the second transparent resin sheet P2by the toner image as the adhesive. The second transparent resin sheet P2is overlaid on the front side of the first transparent resin sheet P1on which the toner image is fixed in the fixing process. In the present embodiment, the adhesion process is performed by at least one of the fixing device20and the registration roller pair28that transports the sheet P toward the image forming device. That is, the registration roller pair28and the fixing device20function as an adhesion device to bond the first transparent resin sheet P1and the second transparent resin sheet P2.

FIGS. 5A to 5Care schematic diagrams illustrating a process of producing the image recording media PT illustrated inFIGS. 3B and 4B.

When the image recording medium PT is produced, transparent resin sheets are set in the sheet feeding unit26. Further, the “special print mode” is selected by the control panel of the image forming apparatus100or a personal computer communicably connected to the image forming apparatus100. The information image X1to be formed on the image recording medium PT is also input by the control panel or the personal computer.

First, the image forming process and the fixing process are performed on the first transparent resin sheet P1, and the first transparent resin sheet P1is transported to the position of the registration roller pair28as illustrated inFIG. 5A. Specifically, similarly to the “duplex printing mode” described above with reference toFIG. 1, the image forming process and the fixing process are performed on the first transparent resin sheet P1fed from the sheet feeding unit26. The first transparent resin sheet P1on which the desired toner image (information image X1) is fixed is transported to the position of the registration roller pair28via the reverse path K3and the duplex-printing path K4. Thus, the first transparent resin sheet P1is on standby at the position. At that time, the toner image (information image X1) on the front surface of the first transparent resin sheet P1faces downward (the front surface of the first transparent resin sheet P1faces downward).

Then, as illustrated inFIG. 5B, the second transparent resin sheet P2is fed from the sheet feeding unit26toward the position of the registration roller pair28where the first transparent resin sheet P1is on standby. At that time, since the information image X1on the lower surface of the first transparent resin sheet P1is about to be sandwiched between the first transparent resin sheet P1and the second transparent resin sheet P2, a switching member29lifts the first transparent resin sheet P1upward. The switching member29has a shape that does not hinder the conveyance of the second transparent resin sheet P2.

Then, as illustrated inFIG. 5C, in a state in which the tip of the first transparent resin sheet P1and the tip of the second transparent resin sheet P2are aligned at the nip of the registration roller pair28, the registration roller pair28starts rotating, thereby transporting the two transparent resin sheets P1and P2. As a result, the pressure of the nip of the registration roller pair28causes the information image X1serving as the adhesive to bond the first and second transparent resin sheet P1and P2.

Specifically, since not much time has passed since the fixing process has been performed on the first transparent resin sheet P1on standby at the position of the registration roller pair28, the two transparent resin sheets P1and P2pass through the nip of the registration roller pair28with the information image X1(toner image) whose temperature is high to certain extent. Therefore, the information image X1(toner image) sufficiently functions as the adhesive even with only the pressure by the registration roller pair28, thereby bonding the two transparent resin sheets P1and P2. Thus, the image recording medium PT in which the two transparent resin sheets P1and P2are bonded is produced.

Thereafter, the image recording medium PT produced at the position of the registration roller pair28passes through the secondary transfer nip and then the fixing device20, and is ejected from the image forming apparatus100via the ejection path K2. At that time, pressure is applied to the two transparent resin sheets P1and P2in a state in which the information image X1(toner image) is heated and melted by the pressure and heat by the fixing device20. Therefore, the adhesive strength between the two transparent resin sheets P1and P2using the information image X1(toner image) as the adhesive is enhanced.

FIG. 6Ais a schematic view of first and second transparent resin sheets P1and P2according to Variation 1 as viewed from the front side, andFIG. 6Bis a side view of an image recording medium PT according to Variation 1 formed by bonding the first and second transparent resin sheets P1and P2.FIGS. 6A and 6Bcorrespond toFIGS. 3A and 3Bin the above-described embodiment, respectively.FIGS. 7A to 7Dare schematic diagrams illustrating a process of producing the image recording medium PT according to Variation 1, corresponding toFIGS. 5A to 5Cin the above-described embodiment.

Similarly to the above-described embodiment, the image recording medium PT according to Variation 1 is also formed by bonding together the two transparent resin sheets P1and P2using the toner image (information image X1) as the adhesive. However, there is a difference in the toner (information image) used as the adhesive.

In Variation 1, as illustrated inFIG. 6A, the information image X1(first toner image) intended by a user is formed on almost the entire surface of the first transparent resin sheet P1. The information image X1(first toner image) is formed in single color or mixed multiple colors among yellow, magenta, cyan, black, and special color. An information image X2(second toner image) that is a mirror image of the information image X1(first toner image) on the first transparent resin sheet P1is formed on the front surface of the second transparent resin sheet P2. That is, the toner image includes two information images X1and X2.

In the example ofFIG. 6A, the letter “R” is formed at the center of the surface of the first transparent resin sheet P1, and the other portion is formed in a different color. The information image X2obtained by inverting the information image X1on the first transparent resin sheet P1is formed on the surface of the second transparent resin sheet P2. Then, the first and second transparent resin sheets P1and P2are overlaid so that the information images X1formed on the front surface of the first transparent resin sheet P1and the information image X2formed on the front surface of the second transparent resin sheet P2are interposed between the first and second transparent resin sheets P1and P2while being superimposed one on another. At that time, pressure and heat (or only pressure) are applied to the two transparent resin sheets P1and P2that are overlaid, thereby producing the image recording medium PT illustrated inFIG. 6Bwith the information images X1and X2(first and second toner images) serving as the adhesive.

In the image recording medium PT produced as described above, the information images X1and X2formed on the first and second transparent resin sheets P1and P2are visible in the direction indicated by the white arrow inFIG. 6Bwith the second transparent resin sheet P2as the front side.

When the image recording medium PT according to Variation 1 is produced using the image forming apparatus100, in addition to the image forming process (i.e., first image forming process), the fixing process (i.e., first fixing process), and the adhesion process described above with reference toFIGS. 5A to 5C, a second image forming process and a second fixing process are performed.

The second image forming process is a process of forming the information image X2(second toner image) on the front surface of the second transparent resin sheet P2and is performed by the image forming device of the image forming apparatus100. The information image X2(second toner image) formed on the front surface of the second transparent resin sheet P2in the second image forming process is a mirror image of the information image X1(first toner image) of the first transparent resin sheet P1.

The second fixing process is a process of applying pressure and heat to the information image X2(second toner image) formed on the front surface of the second transparent resin sheet P2in the second image forming process to fix the information image X2(second toner image) on the front surface and performed by the fixing device20.

The adhesion process according to Variation 1 is a process of applying pressure, or pressure and heat to the overlaid two sheets P1and P2to bond the first transparent resin sheet P1and the second transparent resin sheet P2by the information images X1and X2(first toner image and second toner image) as the adhesive in a state in which the second transparent resin sheet P2on which the information image X2is fixed is overlaid on the first transparent resin sheet P1on which the information image X1is fixed while the front surface of the second transparent resin sheet P2and the front surface of the first transparent resin sheet P1face each other. Also in Variation 1, the adhesion process is performed by at least one of the registration roller pair28and the fixing device20.

FIGS. 7A to 7Dare schematic diagrams illustrating a process of producing the image recording medium PT illustrated inFIG. 6B.

First, the first image forming process and the first fixing process are performed on the first transparent resin sheet P1, and the first transparent resin sheet P1is transported to the position of the registration roller pair28as illustrated inFIG. 7A. Similar to the duplex printing mode described above with reference toFIG. 1, the first image forming process and the first fixing process are performed on the first transparent resin sheet P1fed from the sheet feeding unit26. The first transparent resin sheet P1on which the desired toner image (information image X1) is fixed is transported to the position of the registration roller pair28via the reverse path K3and the duplex-printing path K4. At that time, the first toner image (information image X1) on the front surface of the first transparent resin sheet P1faces downward.

Then, as illustrated inFIG. 7B, the first transparent resin sheet P1is further transported toward the position of the registration roller pair28via the reverse path K3and the duplex-printing path K4, and the second transparent resin sheet P2is fed from the sheet feeding unit26to form the information image X2at the secondary transfer nip in the second image forming process.

Thus, the second image forming process and the second fixing process are performed. Thereafter, as illustrated inFIG. 7C, the second transparent resin sheet P2on which the desired toner image (information image X2) is fixed is transported, via the reverse path K3and the duplex-printing path K4, toward the position of the registration roller pair28where the first transparent resin sheet P1is on standby. At that time, the information image X1(first toner image) on the front surface of the first transparent resin sheet P1faces upward, and the information image X2(second toner image) on the front surface of the second transparent resin sheet P2faces downward. Therefore, to superimpose the information image X1on the upper surface of the first transparent resin sheet P1and the information image X2on the lower surface of the second transparent resin sheet P2, the second transparent resin sheet P2is transported above the first transparent resin sheet P1positioned below under the gravity. The switching member29does not lift the first transparent resin sheet P1.

Then, as illustrated inFIG. 7D, in a state in which the tip of the first transparent resin sheet P1and the tip of the second transparent resin sheet P2are aligned at the nip of the registration roller pair28, the registration roller pair28starts rotating, thereby transporting the two transparent resin sheets P1and P2. As a result, pressure of the nip of the registration roller pair28causes the information images X1and X2as the adhesive to bond the first and second transparent resin sheet P1and P2.

Thereafter, the image recording medium PT produced at the position of the registration roller pair28passes through the secondary transfer nip and then the fixing device20, and is ejected from the image forming apparatus100via the ejection path K2. At that time, in the image recording medium PT, the two transparent resin sheets P1and P2are more strongly bonded by pressure and heat by the fixing device20.

In Variation 1, effects similar to those of the above-described embodiments are also attained.

FIG. 8Ais a schematic view of first and second transparent resin sheets P1and P2according to Variation 2 as viewed from the front side, andFIG. 8Bis a side view of an image recording medium PT according to Variation 2 formed by bonding the first and second transparent resin sheets P1and P2.FIGS. 8A and 8Bcorrespond toFIGS. 3A and 3Bin the above-described embodiment, respectively.

Similarly to the above-described embodiment, the image recording medium PT according to Variation 2 is also formed by bonding the two transparent resin sheets P1and P2using the toner image (information image X1) as the adhesive. In addition to the information image X1(toner image) as the adhesive, a background image Y1(solid image) is used, differing from the image recording medium PT of the above-described embodiment.

In Variation 2, as illustrated inFIG. 8A, the information image X1(toner image) that is a mirror image of an image intended by a user is formed on the front surface of the first transparent resin sheet P1. Additionally, the background image Y1as the solid image is formed so as to cover the information image X1. That is, the toner image includes the information image X1and the background image Y1.

In the example ofFIG. 8A, the information image X1that is a mirror image in which the letter “R” is inverted is formed on the surface of the first transparent resin sheet P1and the monochrome background image Y1as the solid image is formed in the entire area where images can be formed (i.e., area except for the margin defined by the setting of the image forming apparatus100or image-formable area) of the first transparent resin sheet P1. Then, the first and second transparent resin sheets P1and P2are overlaid so that the information image X1and the background image Y1formed on the front surface of the first transparent resin sheet P1are interposed between the first and second transparent resin sheets P1and P2. At that time, pressure and heat (or only pressure) are applied to the two transparent resin sheets P1and P2that are overlaid, thereby producing the image recording medium PT illustrated inFIG. 8Bby the information images X1and the background image Y1(toner image) serving as the adhesive.

In the image recording medium PT produced as described above, the information image X1on the background image Y1is visible when viewed from the first transparent resin sheet P1in the direction indicated by the white arrow inFIG. 8B.

As described above, in Variation 2, the toner image as the adhesive that bonds the two transparent resin sheets P1and P2includes the background image Y1(solid image) in addition to the information image X1.

In the image recording medium PT according to Variation 2, the background image Y1(solid image) is preferably formed in a color other than yellow, magenta, cyan, and black. This background image Y1makes the information image X1formed in a single color or a plurality of colors selected from yellow, magenta, cyan, and black recognizable. That is, the color reproducibility of the information image X1formed on the background image Y1is improved.

In particular, in the image recording medium PT according to Variation 2, when the background image Y1(solid image) is formed in white, the legibility of the information image X1formed on the background image Y1is further improved.

Here, the process of producing the image recording medium PT according to Variation 2 is substantially the same as the production process described above with reference toFIGS. 5A to 5C. However, the toner image formed on the front surface of the first transparent resin sheet P1in the image forming process includes the mirror image (information image X1) formed directly on the front surface of the first transparent resin sheet P1and the solid image (background image Y1) formed over the entire image-formable area of the first transparent resin sheet P1so as to cover the mirror image (information image X1).

In such an image forming process, the mirror image (information image X1) and the solid image (background image Y1) are superimposed on the intermediate transfer belt8, and then the superimposed images X1and Y1are transferred to the first transparent resin sheet P1at the position of the secondary transfer nip. In this case, when the same color toner (or the same process cartridge) is used to form the information image X1and the background image Y1, or when the information image X1is not overlaid on the background image Y1on the intermediate transfer belt8due to the arrangement of the process cartridges6Y,6M,6C,6K, and6S, the image forming process is performed so that the intermediate transfer belt8passes through the positions of the process cartridges6Y,6M,6C,6K, and6S twice or more.

In Variation 2, effects similar to those of the above-described embodiments are also attained.

FIG. 9Ais a schematic view of first and second transparent resin sheets P1and P2according to Variation 3 as viewed from the front side, andFIG. 9Bis a side view of an image recording medium PT according to Variation 3 formed by bonding the first and second transparent resin sheets P1and P2.FIGS. 9A and 9Bcorrespond toFIGS. 3A and 3Bin the above-described embodiment, respectively.

Similarly to Variation 2, in the image recording medium PT according to Variation 3, the toner image as the adhesive that bonds the two transparent resin sheets P1and P2includes a background image Y2(solid image) in addition to the information image X1. In the production process, the background image Y2(solid image) is formed on the second transparent resin sheet P2, differing from the image recording medium PT in the Variation 2.

In Variation 3, as illustrated inFIG. 9A, the information image X1(first toner image) is formed as the mirror image on the front surface of the first transparent resin sheet P1. A background image Y2(second toner image) as a solid image is formed on the front surface of the second transparent resin sheet P2.

In the example ofFIG. 9A, the information image X1that is the mirror image in which the letter “R” is inverted is formed on the surface of the first transparent resin sheet P1and the monochrome background image Y2as the solid image is formed in the entire image-formable area (i.e., area except for the margin defined by the setting of the image forming apparatus100) of the second transparent resin sheet P2. Then, the first and second transparent resin sheets P1and P2are overlaid so that the information images X1formed on the front surface of the first transparent resin sheet P1and the background image Y2formed on the front surface of the second transparent resin sheet P2are interposed between the first and second transparent resin sheets P1and P2. At that time, pressure and heat (or only pressure) are applied to the two transparent resin sheets P1and P2that are overlaid, thereby producing the image recording medium PT illustrated inFIG. 9Bby the information images X1and the background image Y2(first and second toner images) serving as the adhesive.

In the image recording medium PT produced as described above, the information image X1on the background image Y2is visible when viewed from the first transparent resin sheet P1in the direction indicated by the white arrow inFIG. 9B.

Note that, the background image Y2(solid image) formed in a color other than yellow, magenta, cyan, and black (in particular, formed in white) improves the color reproducibility of the information image X1formed on the background image Y2.

Here, the process of producing the image recording medium PT according to Variation 3 is substantially the same as the production process described above with reference toFIGS. 7A to 7D. However, the second toner image formed on the front surface of the second transparent resin sheet P2in the second image forming process is the solid image (background image Y2) formed over the entire image-formable area of the second transparent resin sheet P2.

In Variation 3, effects similar to those of the above-described embodiments are also attained.

FIG. 10Ais a schematic view of first and second transparent resin sheets P1and P2according to Variation 4 as viewed from the front side, andFIG. 10Bis a side view of an image recording medium PT according to Variation 4 formed by bonding the first and second transparent resin sheets P1and P2.FIGS. 10A and 10Bcorrespond toFIGS. 3A and 3Bin the above-described embodiment, respectively.

Similarly to Variations 2 and 3, in the image recording medium PT according to Variation 4, the toner image as the adhesive that bonds the two transparent resin sheets P1and P2includes the information image X1and the background images Y1and Y2(solid image). In addition to the information image X1visible when viewed from one side of the image recording medium PT, the information image X2is formed so that the information image X2is visible when viewed from the other side of the image recording medium PT, differing from the image recording media PT in the Variations 2 and 3. That is, in the image recording medium PT according to Variation 4, the two information images X1and X2are formed on the front surfaces of the first and second transparent resin sheet P1and P2, respectively, so as to sandwich the background images Y1and Y2(solid images). That is, the information image X1is formed on one side of the image recording medium PT with respect to the background images Y1and Y2, and the information image X2is formed on the other side of the image recording medium PT with respect to the background images Y1and Y2. As a result, the information images X1and X2are visible when viewed from the one side and the other side, respectively.

In Variation 4, as illustrated inFIG. 10A, the information image X1as the mirror image formed on the front surface of the first transparent resin sheet P1. Additionally, the background image Y1as the solid image is formed so as to cover the information image X1. That is, the first toner image includes the information image X1and the background image Y1. The information image X2as the mirror image formed on the front surface of the second transparent resin sheet P2. Additionally, the background image Y2as the solid image is formed so as to cover the information image X2. That is the second toner image includes the information image X2and the background image Y2.

In the example ofFIG. 10A, the information image X1that is the mirror image of the intended image in which the letter “R” is inverted is formed at the center of the surface of the first transparent resin sheet P1, and the background image Y1as the solid image is formed in the entire image-formable area where images can be formed of the first transparent resin sheet P1so as to cover the information image X1(mirror image). Further, the information image X2that is a mirror image of an intended image in which the character “N” is inverted is formed at the center of the surface of the second transparent resin sheet P2and the background image Y2as the solid image is formed in the entire image-formable area where images can be formed of the second transparent resin sheet P2so as to cover the information image X2(mirror image).

Then, the first and second transparent resin sheets P1and P2are overlaid so that the information images X1and the background image Y1formed on the front surface of the first transparent resin sheet P1and the information image X2and the background image Y2formed on the front surface of the second transparent resin sheet P2are interposed between the first and second transparent resin sheets P1and P2. At that time, pressure and heat (or only pressure) are applied to the two transparent resin sheets P1and P2that are overlaid, thereby producing the image recording medium PT illustrated inFIG. 10Bby the information images X1and X2and the background images Y1and Y2serving as the adhesive.

In the image recording medium PT produced as described above, the information image X1on the background image Y1is visible when viewed from the first transparent resin sheet P1, and the information image X2on the background image Y2is visible when viewed from the second transparent resin sheet P2in the direction indicated by the white arrow inFIG. 10B.

The background images Y1and Y2(solid images) may be formed in any color (for example, yellow, magenta, cyan, and black). However, the background images Y1and Y2(solid images) formed in a color other than yellow, magenta, cyan, and black (in particular, formed in white) improves the color reproducibility of the information images X1and X2formed on the background images Y1and Y2, respectively.

Here, the process of producing the image recording medium PT according to Variation 4 is substantially the same as the production process described above with reference toFIGS. 7A to 7D. However, the second toner image formed on the front surface of the second transparent resin sheet P2in the second image forming process includes the mirror image (information image X2) formed directly on the front surface of the second transparent resin sheet P2, and the solid image (background image Y2) formed over the entire image-formable area of the second transparent resin sheet P2so as to cover the mirror image (information image X2).

Similarly to the first image forming process described in Variation 2, the second image forming process may be performed so that the intermediate transfer belt8passes through the positions of the process cartridges6Y,6M,6C,6K, and6S twice or more, as required.

In Variation 4, effects similar to those of the above-described embodiments are also attained. In particular, in Variation 4, the duplex printed image recording medium PT can be provided that has high water resistance and durability and is less likely to curl.

FIG. 11Ais a schematic view of first and second transparent resin sheets P1and P2according to Variation 5 as viewed from the front side, andFIG. 11Bis a side view of an image recording medium PT according to Variation 5 formed by bonding the first and second transparent resin sheets P1and P2.FIGS. 11A and 11Bcorrespond toFIGS. 3A and 3Bin the above-described embodiment, respectively.

Similarly to Variation 2, in the image recording medium PT according to Variation 5, the toner image as the adhesive that bonds the two transparent resin sheets P1and P2includes the information image X1and the background image Y1(solid image). Further, the background image Y2(solid image) is formed on the second transparent resin sheet P2, differing from the image recording medium PT in the Variation 2.

In Variation 5, as illustrated inFIG. 11A, the information image X1as the mirror image is formed on the front surface of the first transparent resin sheet P1. Additionally, the background image Y1as the solid image is formed so as to cover the information image X1. That is, the first toner image includes the information image X1and the background image Y1. The background image Y2(second toner image) as the solid image is formed on the front surface of the second transparent resin sheet P2.

In the example ofFIG. 11A, the information image X1that is the mirror image of the intended image in which the letter “R” is inverted is formed at the center of the surface of the first transparent resin sheet P1, and the background image Y1as the solid image is formed in the entire image-formable area, where images can be formed, of the first transparent resin sheet P1. Further, the background image Y2as the solid image is formed in the entire image-formable area on the surface of the second transparent resin sheet P2.

Then, the first and second transparent resin sheets P1and P2are overlaid so that the information images X1and the background image Y1formed on the front surface of the first transparent resin sheet P1and the background image Y2formed on the front surface of the second transparent resin sheet P2are interposed between the first and second transparent resin sheets P1and P2. At that time, pressure and heat (or only pressure) are applied to the two transparent resin sheets P1and P2that are overlaid, thereby producing the image recording medium PT illustrated inFIG. 11Bby the information image X1and the background images Y1and Y2serving as the adhesive.

In the image recording medium PT produced as described above, the information image X1on the background images Y1and Y2is visible when viewed from the first transparent resin sheet P1in the direction indicated by the white arrow inFIG. 11B.

The background images Y1and Y2(solid images) may be formed in any color (for example, yellow, magenta, cyan, and black). However, the background images Y1and Y2(solid images) formed in a color other than yellow, magenta, cyan, and black (in particular, formed in white) improves the color reproducibility of the information image X1formed on the background images Y1and Y2.

Here, the process of producing the image recording medium PT according to Variation 5 is substantially the same as the production process described above with reference toFIGS. 7A to 7D. However, the second toner image formed on the front surface of the second transparent resin sheet P2in the second image forming process is the solid image (background image Y2) formed over the entire image-formable area of the second transparent resin sheet P2.

In Variation 5, effects similar to those of the above-described embodiments are also attained. In particular, in Variation 5, since the background images Y1and Y2are layered, the legibility of the information image X1is further improved.

As described above, the image recording medium PT according to the above-described embodiments includes the two sheets P1, P2and a toner image interposed between the two sheets P1and P2. The toner image serves as an adhesive to bond the two sheets P1and P2and includes an information image X1. At least one of the two sheets P1and P2has a transparent portion to enable the information image X1to be visible through the at least one of the two sheets P1and P2.

With this configuration, an image recording medium having high water resistance can be provided. Therefore, according to the present disclosure, an image recording medium having high water resistance, a method of producing the image recording medium, and an image forming apparatus can be provided.

In the present embodiment, the two sheets (first and second transparent resin sheets P1and P2) are bonded by the toner image to form the image recording medium PT, in which entire areas of the two sheets are transparent. Alternatively, two sheets, in which a part of areas of the two sheets are transparent, can be bonded by the toner image to form the image recording medium.

In such configurations, effects similar to those described above are also attained.

In the above-described embodiments, the two transparent resin sheets P1and P2are bonded by the toner image to form the image recording medium PT. However, both of the two sheets P1and P2of the image forming recording medium PT are not necessarily transparent water-resistant sheets. Even when one of the two sheets P1and P2is a transparent water-resistant sheet and the other is an opaque water-resistant sheet, effects similar to those described above are also attained.

For example, a transparent resin sheet and a white resin sheet (a white sheet made of resin that is a water-resistant material) can be bonded by the toner image to form the image recording medium PT. In this case, an information image (single-sided image) can be visible only when viewed from the transparent resin sheet. However, the legibility of the information image (single-sided image) can be improved as compared with the case in which a white solid image (background image) is formed between the two sheets and an information image is formed between the white solid image and the transparent resin sheet.

Further, a transparent resin sheet and a black resin sheet (a black sheet made of resin that is a water-resistant material) can be bonded by toner to form the image recording medium PT. In this case, an information image formed in colors other than black (in particular, formed in white) can be visible only when viewed from the transparent resin sheet. However, the legibility of the information image (single-sided image) can be improved as compared with the case in which a black solid image (background image) is formed between the two sheets and a white information image is formed between the black solid image and the transparent resin sheet.

The above-described embodiments are illustrative and do not limit the present disclosure. Thus, numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that within the scope of the present disclosure, the present disclosure may be practiced otherwise than as specifically described herein. The number, position, and shape of the components described above are not limited to those embodiments described above. Desirable number, position, and shape can be determined to perform the present disclosure.

In the present disclosure, the term “mirror image” is defined as an image obtained by inverting an image intended by a user to be formed (or inverting an original image) as if the image is reflected in a mirror.