JP5157719B2 - Information display medium, printing apparatus and printing method - Google Patents

Description

  The present invention relates to an information display medium excellent in confidentiality, a printing apparatus, and a printing method.

  In recent years, leakage of confidential information printed on paper media has become a social problem. In order to solve this problem, a technique has been disclosed in which characters or the like printed on a paper medium are naturally erased with time (see, for example, Patent Document 1).

In this technique, a leuco dye and a developer are used as ink. The ink used in this technology has the characteristic that the color is naturally erased with time, and by using this feature, a paper medium is proposed in which confidential information is naturally erased and cannot be read. Has been.
JP 2004-223898 A

  However, in the technique disclosed in Patent Document 1, when the paper medium is heated after erasing, the ink is colored again, so it is difficult to ensure confidentiality.

  Also, with the technique disclosed in Patent Document 1, depending on the type of paper medium, the color of ink after completion of natural decoloring may not be completely transparent. For this reason, even after erasing, the information printed on the paper medium can be read lightly, that is, the information confidentiality is sometimes lost.

  The present invention has been made in view of the above problems. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an information display medium, a printing apparatus, and a printing method in which information cannot be read again once the color is erased.

  The inventor of the present invention uses a functional ink having a property of naturally decoloring and a property of developing color by adding a common physical operation, and displays information with the first functional ink in a colored state. It has been conceived that the above-described problems can be solved if an information display medium having a structure in which the second functional ink having the same color as the first functional ink in a decolored state is applied covering this information.

  Therefore, according to the information display medium of the present invention, the colors change from the first and second coloring states to the transparent first and second decoloring states over time, and the first and second functions. The first and second functional inks that change in color from the first and second decolored states to the first and second colored states, respectively, by applying a physical operation common to the functional inks on the ground Information is displayed.

  Here, the colors of the first and second functional inks in the first and second coloring states are in a state that is not visually distinguished from each other, and are in the first and second decoloring states. The respective colors of the second functional ink are indistinguishable from each other visually.

On the surface region of the base, information display regions are found provided, first functional ink, in the information display area is provided in a first color state and a second functional ink, It is applied in a second decolored state to the area on the base including the information display area, and is superimposed on the first functional ink in the information display area .

  In this information display medium, the base is preferably paper.

  In this information display medium, it is preferable that the first and second functional inks are heat-sensitive inks and the physical operation is heating.

  In this information display medium, it is preferable that the first and second functional inks contain a leuco dye and a developer as main components.

In this case , the second functional ink is a regular or irregular pattern that can prevent information from being read when the first and second functional inks are in the first and second decolored states, respectively. Thus, it is preferably applied in the information display area.

  The printing apparatus according to the present invention changes in color from the first and second coloring states to the transparent first and second decoloring states over time, and is common to the first and second functional inks. By applying a physical operation, information is printed on the ground using first and second functional inks that change colors from the first and second decoloring states to the first and second coloring states, respectively.

  Here, the colors of the first and second functional inks in the first and second coloring states are in a state that is not visually distinguished from each other, and are in the first and second decoloring states. The respective colors of the second functional ink are indistinguishable from each other visually.

  In addition, the printing apparatus prints the first functional ink in the information display area partitioned on the surface of the base and provides the first printing state in the first coloring state, and the second printing state in the second erasing state. And a second printing unit that applies functional ink to an area including the information display area.

  In the printing apparatus, the first printing unit includes a printing unit that prints the first functional ink in the first decoloring state, and a coloring unit that changes the printed first functional ink to the first coloring state. It is preferable to provide.

In this printing apparatus, it is preferable that heat-sensitive ink is used as the first and second functional inks, and that the coloring means is a heating means.
In this printing apparatus, it is preferable to further include a cooling unit that cools the first functional ink to a temperature lower than the coloring temperature between the first and second printing units.

  The printing method of the present invention is common to the first and second functional inks as the color changes over time from the first and second coloring states to the first and second decoloring states that are both transparent. Printing information on the ground using first and second functional inks that change color from the first and second decolored states to the first and second colored states by applying physical operations, respectively. It is.

  Here, the colors of the first and second functional inks in the first and second coloring states are in a state that is not visually distinguished from each other, and are in the first and second decoloring states. The respective colors of the second functional ink are indistinguishable from each other visually.

  This printing method includes a first printing step in which a first functional ink is printed in a first coloring state in an information display area partitioned on the surface of the base, and a second functionality in a second decoloring state. A second printing step of applying ink to a region including the information display region.

  In this printing method, the first printing step includes a printing sub-step for printing the first functional ink in the first decoloring state, and a coloring sub-step for changing the printed first functional ink to the first coloring state. Are preferably provided.

In this printing method, heat-sensitive ink is used as the first and second functional inks, and it is preferable to heat the first functional ink printed in the coloring sub-process.
In this printing method, it is preferable to further include a cooling step of cooling the first functional ink to a temperature lower than the color development temperature between the first and second printing steps.

  The present invention has the above-described configuration. Therefore, according to the information display medium, the printing apparatus, and the printing method of the present invention, an information display medium in which information cannot be read again when the color is erased is obtained.

  Embodiments of the present invention will be described below with reference to the drawings. Each drawing is merely a schematic representation of the shape, size, and arrangement relationship of each component to the extent that the present invention can be understood. Moreover, although the preferable structural example of this invention is demonstrated hereafter, the material of each component, a numerical condition, etc. are only a suitable example. Therefore, the present invention is not limited to the following embodiments. Moreover, in each figure, the same code | symbol is attached | subjected to a common component and the description may be abbreviate | omitted.

(Embodiment 1)
With reference to FIGS. 1-3, the information display medium of Embodiment 1 is demonstrated. FIG. 1A is a plan view of an information display medium according to an embodiment. FIG. 1B is a cut end view taken along line AA in FIG.

With reference to FIG. 1 (A) and (B), a base 12 on the information display medium 10, a first functional ink 14 that is displaying the information on the base 12, the information of the first functional ink 14 A second functional ink 16 applied to an area including the display area 18 is provided.

  In the example of FIG. 1, the base 12 is preferably paper having a thickness, for example, a rectangular planar shape. However, the base 12 is not limited to paper, and any suitable material according to the design, such as a plastic board, a wooden board, or a cloth, can be selected.

  The first main surface 12a of the base 12 is referred to as the upper surface or simply the surface. The surface area of the base is previously divided into an information display area 18 and a non-information display area 17, and a plurality of information display areas 18 are provided apart from each other although not shown. In the information display area 18, information is provided and displayed by the first functional ink 14 in the first coloring state (details will be described later). More specifically, information is printed with the first functional ink 14 in a pattern such as characters and figures. Here, the first functional ink 14 is shown as an example in which information is displayed with a character pattern “Hi” in hiragana.

  Further, the second functional ink 16 is applied to the first main surface 12a of the base 12, that is, the surface region. The second functional ink 16 may be applied to both the information display area 18 and the non-information display area 17 or may be applied only to the information display area 18. In the example shown in the drawing, both the information display area 18 and the non-information display area 17, and thus the entire surface area, are covered with the second decoloring state (details will be described later) so as to cover the first functional ink 14. The second functional ink 16 is applied.

  Next, the characteristics of the functional inks 14 and 16 will be described in detail.

That is, in the first functional ink 14, the color developed from the first color developing state to the first decoloring state is changed lightly over time, and finally the color disappears. . The organic by applying physical operation, basically, the colored non characteristic color to the first colored state which is colored with a color visible to the visible light and color from the first color erasing state changes doing.

  The characteristics of the first functional ink 14 will be described in more detail. The first functional ink 14 is in a first decolored state at room temperature, that is, in a state of high transparency under visible light. That is, the transmittance of light passing through the first functional ink layer which is an optical medium is large. In this case, when the base 12 is white, the information printed with the first functional ink 14 is less colored, that is, the degree is low, but the information may be readable when viewed with the naked eye. There is. Therefore, in this specification, it is referred to as “high transparency” or “high transparency” unless there is a problem including a state of high transparency including a state of being completely transparent.

  The first functional ink 14 in the first decolored state changes to a first colored state, that is, a colored state that can be seen with visible light, when a physical operation of heating to a coloring temperature higher than room temperature is applied. The degree or degree of coloring due to color development is deep, and the ink layer is opaque or in a state of low transparency. In this specification, such a state is referred to as “high color development” or “high coloration”. Further, the degree of coloring, that is, the state where the degree is low, is referred to as “low coloring degree” or “low coloring degree”.

  In addition, the first functional ink 14 is under physical conditions different from the conditions for color development. Therefore, for example, if the first functional ink 14 is left at room temperature in the first color development state, the color developed gradually becomes lighter and the coloring degree decreases. And it has the characteristic which changes to a 1st decoloring state (substantially transparent). The time required to change from the first coloring state to the first decoloring state can be adjusted by the composition of the first functional ink 14.

  The first functional ink 14 is preferably a heat-sensitive ink containing, for example, a leuco dye and a developer.

  Here, leuco dyes include, for example, 2-anilino-3-methyl-6-diethylaminofluorane 2-anilino-3-methyl-6- (di-n-butylamino) fluorane, 2-anilino-3- Methyl-6- (Nn-propyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N-isopropyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N-isobutyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (Nn-amyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N-sec -Butyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (Nn-amyl-N-ethylamino) fluorane, 2-anilino-3-methyl-6- (N- so-amyl-N-ethylamino) fluorane, 2-anilino-3-methyl-6- (Nn-propyl-N-isopropylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexyl- N-methylamino) fluorane, 2-anilino-3-methyl-6- (N-ethyl-p-toluidino) fluorane, 2-anilino-3-methyl-6- (N-methyl-p-toluidino) fluorane, 2 -(M-trichloromethylanilino) -3-methyl-6-diethylaminofluorane, 2- (m-trifluoromethylanilino) -3-methyl-6-diethylaminofluorane, 2- (m-trichloromethylaniline) Lino) -3-methyl-6- (N-cyclohexyl-N-methylamino) fluorane, 2- (2,4-dimethylanilino) -3-me Lu-6-diethylaminofluorane, 2- (N-ethyl-p-toluidino) -3-methyl-6- (N-ethylanilino) fluorane, 2- (N-ethyl-p-toluidino) -3-methyl-6 -(N-propyl-p-toluidino) fluorane and the like are preferred.

In addition, as the developer, for example, the molecule has all the structures composed of a hydroxy aromatic hydrocarbon group, an ether bond, and a salt of a carboxylic acid and an amine at the same time . Specific examples of the developer include, for example, a carboxylic acid having at least one of a first hydroxy aromatic hydrocarbon group and a first ether bond, a second hydroxy aromatic hydrocarbon group, and a second A substance substantially consisting of a salt with an amine having at least one of ether bonds is preferred.

  In the second functional ink 16, the color developed from the second coloring state to the second decoloring state gradually changes over time, and under certain physical conditions, therefore, by applying a physical operation, The color developed from the second decoloring state to the second coloring state is changed to make the color darker, that is, the coloring degree is increased.

  The characteristics of the second functional ink 16 will be described in more detail. The second functional ink 16 is in the second decolored state, i.e., almost transparent, at room temperature. However, when the physical operation of heating above the coloring temperature higher than room temperature is applied, the second functional ink 16 is in the second coloring state, i.e., opaque or low in transparency. The transmittance changes to a small state.

  In addition, the second functional ink 16 is similar to the first functional ink 14 under physical conditions different from the above-described physical conditions for color development. If left untreated, the color developed gradually becomes lighter, the coloring degree is lowered, and the second decoloring state is changed. The time required to change from the second coloring state to the second decoloring state can be adjusted by the composition of the second functional ink 16.

  In this embodiment, in the first and second functional inks 14 and 16, the colors in the first and second coloring states are preferably the same color, that is, the same. In that case, in the first and second coloring states, the first and second functional inks 14 and 16 exhibit colors that are not visually recognized.

  The colors in the first and second decoloring states are preferably the same color, that is, the same. In that case, in the first and second decolored states, the first and second functional inks 14 and 16 exhibit a color that is not visually recognized.

  Even if the color to be developed is not the same color, it is sufficient that the layers of the first and second functional inks cannot be identified visually. Accordingly, here, “the colors are equal” means that between the two points corresponding to the first and second decolored states when the color is expressed as a point inside the conventionally known L * a * b * color sphere. The color difference ΔE between the two points corresponding to the first and second color development states is 0.3 or less, respectively.

  In general, when the color difference ΔE between two points in the L * a * b * color sphere is 0.3 or less, it is known that the two colors are in an indistinguishable state.

  Therefore, in this embodiment, it is preferable to use the same kind of heat-sensitive ink with the same color as the first and second functional inks 14 and 16, but the color to be developed is not the same color. Alternatively, different types of heat-sensitive inks having a color difference ΔE of both colors of 0.3 or less may be used.

  The temperatures at which the first and second functional inks 14 and 16 change from the first and second decoloring states to the first and second coloring states (hereinafter simply referred to as “coloring temperatures”), respectively. Are preferably equal to each other.

  Next, the operation of this embodiment will be described with reference to FIGS. FIG. 2A is a plan view schematically showing the state of the information display medium immediately after printing. FIG. 2B is a plan view schematically showing the state of the information display medium when a predetermined time has elapsed from FIG. 2A and the first functional ink is in the first decolored state (substantially transparent). FIG. FIG. 2C is a plan view schematically showing the state of the information display medium after the heating operation is applied to FIG.

  Referring to FIG. 2A, immediately after printing, “a” character pattern as character information is formed as a pattern layer in the information display area 18 of the base 12 with the first functional ink 14 in the first coloring state (opaque). It is printed. In this case, the character pattern is colored black and is substantially in a state of low transparency. Then, the first functional ink 14 is covered and the area on the base 12 including the information display area 18, that is, both the information display area 18 and the non-information display area 17, are in the second decolored state. Bifunctional ink 16 is applied in layers. In this example, the second functional ink 16 is applied to the first main surface of the base 12, that is, the entire surface region 12a.

  In this case, since the layer of the second functional ink 16 applied to the entire surface of the first main surface 12a is in a state of low coloring and high transparency, it is in the first coloring state, that is, the transparency is low. By visually observing the information displayed on the base 12 with the layer of the first functional ink 14, the layer of the character pattern of the lower first functional ink 14 can be recognized through the layer of the second functional ink 16, and accordingly, It is possible to decipher the letter “A”.

  Next, the state of the information display medium 10 when the first functional ink 14 is changed to the first decolored state will be described with reference to FIG.

  The colored color of the first functional ink 14 in the first coloring state (the area partitioned by the dotted line) displaying information in the information display area 18 of the base 12 is gradually erased over time. It changes to the first decoloring state, that is, the state of low coloration and high transparency. On the other hand, the second functional ink 16 applied to the entire surface of the first main surface 12a of the base 12 remains in the second decolored state.

  By the way, since the materials of the first and second functional inks 14 and 16 are the same, the first decolored state of the first functional ink 14 and the second decolored state of the second functional ink 16 are described above. In this state, the colors are equal to each other, and are low in color and high in transparency, and in the same color and transparency. Accordingly, the information displayed in the information display area 18 with the first functional ink 14 in the first decolored state is, to say, the background of the same color, that is, the second functional ink 16 in the second decolored state is applied. As a result, the layers of the first functional ink 14 are camouflaged by the layer of the second functional ink 16 and become unreadable.

  Next, an example in which the information display medium 10 shown in FIG. 2B is heated to a color development temperature higher than room temperature will be described with reference to FIG.

  The physical operation of heating the information display medium 10 (FIG. 2 (B)) whose information has become unreadable due to the first functional ink 14 changing to the first decoloring state to a temperature higher than the coloring temperature is added. Suppose that

  In this case, both the first and second functional inks 14 and 16 are colored with the same color. That is, the first functional ink 14 changes to the first coloring state, and the second functional ink 16 changes to the second coloring state.

  By the way, the first colored state of the first functional ink 14 and the second colored state of the second functional ink 16 have the same color as described above, and have a high coloring degree and low transparency. And are in a state of equal coloring and transparency. Therefore, the information displayed in the information display area 18 with the layer of the first functional ink 14 is assimilated to the layer of the second functional ink 16 in the second coloring state as the background, so that the above-described disappearance. As in the case of the color state, the layer of the first functional ink 14 is just camouflaged with the layer of the second functional ink 16, and thus the information cannot be read by visual observation with the naked eye.

  In summary, the information display medium 10 of this embodiment has the following three features.

  (1) As shown in FIG. 2A, immediately after printing, the information displayed with the first functional ink 14 can be read.

  (2) As shown in FIG. 2B, after a predetermined time has elapsed and the first functional ink 14 displaying information has changed to the first decolored state, information is formed. The character pattern and the background are the same color, so the information as the character pattern becomes unreadable.

  (3) As shown in FIG. 2 (C), even if the information display medium 10 (FIG. 2 (B)) once unreadable is heated again above the coloring temperature higher than room temperature, the first and second Since both the functional inks 14 and 16 are colored, the character pattern and the background thereof are substantially the same color, so that the information as the character pattern becomes unreadable.

  As described above, the information display medium 10 of this embodiment cannot read the information again if the color is erased. That is, when compared with a conventional information display medium that can redisplay information by heating, the information display medium 10 of this embodiment has a markedly improved confidentiality.

  Next, a modification of the information display medium 10 of this embodiment will be described.

  In the example of the embodiment described above, the case where the same kind of functional ink is used as the first and second functional inks 14 and 16 has been described. However, the first and second functional inks 14 and 16 are different if the colors in the first and second erasing states are indistinguishable and the colors in the first and second coloring states are indistinguishable. Optical ink may be used.

  In this embodiment, the case where heat-sensitive ink is used as the first and second functional inks 14 and 16 has been described. However, the first and second functional inks 14 and 16 are not limited to heat-sensitive inks as long as the decolored state and the colored state are reversibly changed by a physical operation common to both inks. .

  For example, it may be an ink that develops or decolors with light such as ultraviolet light, or an ink that develops or decolors with pressure.

  In this embodiment, the case where the second functional ink 16 is applied to the entire surface of the first main surface 12a of the base 12 including the information display area 18 in a manner superimposed on the first functional ink 14 has been described.

  However, the region where the second functional ink 16 is applied is not limited to the entire surface of the first main surface 12a of the base 12. Any area may be used as long as the information displayed on the base 12 becomes unreadable after the first functional ink 14 is decolored.

  For example, as shown in FIG. 3A, the second functional ink 16 may be applied only on the inside of the information display area 18 so as to overlap the first functional ink 14.

  Further, for example, as shown in FIG. 3B, the second functional ink 16 is regularly arranged in a lattice shape by superimposing the first functional ink 14 on a region on the base 12 including the information display region 18. It may also be applied.

  In addition, for example, as shown in FIG. 3C, the second functional ink 16 has an irregular pattern superimposed on the first functional ink 14 in a region on the base 12 including the information display region 18. You may apply as.

  In this embodiment, the case where the second functional ink 16 is applied so as to overlap the first functional ink 14 has been described.

  However, the second functional ink 16 excludes the printing area of the first functional ink 14 on condition that the information displayed on the base 12 becomes unreadable after the first functional ink 14 is decolored. You may apply | coat to the area | region of the foundation | substrate 12 which it was.

  This point will be described in more detail with reference to FIG. FIG. 4 is a cut end view of the base 12 schematically showing a state in which the second functional ink 16 is printed outside the printing area of the first functional ink 14.

  Referring to FIG. 4, the layer of the first functional ink 14 and the layer of the second functional ink 16 do not overlap. Therefore, when the first functional ink 14 is changed to the first decoloring state, the color of the information pattern (first functional ink 14) and the background color (second functional ink 16) are completely equal. Become. Therefore, when the second functional ink 16 is applied in this way, the confidentiality of the information displayed with the first functional ink 14 is further increased.

(Embodiment 2)
With reference to FIG. 5, a printing apparatus and a printing method according to the second embodiment will be described. FIG. 5 is a schematic diagram schematically illustrating a configuration of a printing apparatus used for explaining the printing apparatus and the printing method.

  Referring to FIG. 5, the printing apparatus 50 of this embodiment includes a first printing unit 52 and a second printing unit 54 as main components. Further, the printing apparatus 50 includes a control unit (not shown) and a transport unit 57.

  Hereinafter, each component will be described.

  The first printing unit 52 further includes a printing unit 56 and a coloring unit 58.

  The printing unit 56 includes an ink tank 56a and a print head 56b. The printing unit 56 is provided on the most upstream side in the transport direction of the base 12 (arrow A in the drawing) (hereinafter simply referred to as “transport direction”).

  The ink tank 56a stores the first functional ink 14 in the first decolored state, and is connected to a print head 56b described later.

  The print head 56b prints information on the paper serving as the base 12 using the first functional ink 14 in the first decolored state, based on the information signal transmitted from the control unit. An appropriate amount of the first functional ink 14 is continuously supplied from the ink tank 56a to the print head 56b.

  The coloring unit 58 is provided on the downstream side in the transport direction from the printing unit 56. More specifically, the coloring unit 58 is disposed between the printing unit 56 and the second printing unit 54.

  The color developing unit 58 is a heating roller that heats the first functional ink 14 to a temperature equal to or higher than the color developing temperature. The peripheral surface of the coloring means 58 rotates in synchronization with the transport of the ground while contacting the surface of the ground to be transported.

  The information printed with the first functional ink 14 in the first decolored state is heated to a temperature equal to or higher than the color development temperature by the color development means 58, and the color changes to the first color development state. As a result, the information printed on the base 12 can be read.

  In summary, the first printing unit 52 prints the first functional ink 14 on the base 12 in the first coloring state.

  The second printing unit 54 is provided on the downstream side in the transport direction with respect to the coloring unit 58.

  The second printing unit 54 includes an ink tank 54a and a print head 54b.

  The ink tank 54a stores the second decolored second functional ink 16 and is connected to a print head 54b described later.

  The print head 54b applies the second functional ink 16 in the second decolored state to an area including the information display area 18 of the base 12 based on the information signal transmitted from the control unit. That is, the second functional ink 16 in the second decolored state is applied to the entire surface of the first main surface 12a of the base 12 so as to cover the information printed in a readable state by the first printing unit 52.

  Next, the printing method of this embodiment will be described as an operation of the printing apparatus 50 with reference to FIG.

  The foundation 12 is conveyed in the conveying direction through the printing apparatus 50 by the conveying means 57.

(First printing process)
The first printing process is further subdivided into a printing sub-process and a coloring sub-process.

  In the printing sub-process, the printing unit 56 prints information in the first decolored state using the first functional ink 14 on the conveyed base 12. At this stage, since the first functional ink 14 is in the first decolored state, the information printed on the base 12 is unreadable.

  The coloring sub-process is performed after the printing sub-process. In other words, the base 12 conveyed in the conveyance direction through the printing sub-process subsequently reaches the coloring unit 58. Then, the base 12 is heated to a temperature equal to or higher than the coloring temperature of the first functional ink 14 by coming into contact with the heating roller of the coloring means 58.

  As a result, the first functional ink 14 changes from the first decoloring state to the first coloring state. Thereby, the information printed on the base 12 using the first functional ink 14 can be read.

(Second printing process)
The base 12 that has undergone the first printing step is transported in the transport direction and reaches the second printing unit 54. In the second printing step, the second functional ink 16 in the second decolored state is applied to the area including the information display area 18 of the base 12 by the second printing unit 54. That is, the second functional ink 16 in the second decolored state is applied so as to cover the information printed in a state that can be read by the first printing unit 52.

  Thereby, the information display medium 10 as shown in FIG. 1A is obtained.

  As described above, according to the printing apparatus and the printing method of this embodiment, it is possible to obtain the information display medium 10 that cannot read information again if the color is erased. That is, when compared with a conventional information display medium that can redisplay information by heating, the information display medium 10 with significantly improved confidentiality can be obtained.

  In this embodiment, the case where the printing apparatus (printing direction) includes only the first printing unit 52 (first printing process) and the second printing unit 54 (second printing process) has been described. In particular, when a leuco dye is used as the ink, the first functional ink 14 is cooled between the first printing unit 52 (first printing step) and the second printing unit 54 (second printing step). It is more preferable to provide a cooling means (cooling step) or the like for promoting.

  By doing so, the first functional ink 14 heated to a temperature equal to or higher than the coloring temperature by the coloring means 58 (coloring sub-process) of the first printing unit 52 (first printing process) is rapidly reduced below the coloring temperature. Can be cooled to a temperature of

  In general, leuco dyes are known to develop color more smoothly by rapid cooling after heating to a temperature higher than the color development temperature. Thus, the cooling function (the first function is provided by providing a cooling step). The color development of the conductive ink 14 can be further promoted.

  In addition, since the temperature of the base 12 is lowered by providing the cooling means (cooling process), the second functional ink 16 is erroneously colored in the second printing unit 54 (second printing process). Can be prevented in advance.

  Moreover, in this embodiment, the case where the 2nd functional ink 16 was printed on the 1st functional ink 14 in the 2nd printing process was demonstrated. However, the printing area of the second functional ink 16 may be an area excluding the printing area of the first functional ink 14.

  In this case, for example, the control unit outputs a command to print the “drawing” area to the first printing unit 52, and the “ground” area to the second printing unit 54. What is necessary is just to comprise so that the command to print may be output.

  By configuring in this way, as already explained in the section of the effect of the first embodiment, both the first and second functional inks 14 and 16 are decolored (FIG. 2B). The illegibility of information is further improved.

(A) is a top view of the information display medium of an embodiment. (B) is a cut end view along the AA line of (A). (A) is a top view which shows typically the mode of the information display medium immediately after printing. (B) is a plan view schematically showing the state of the information display medium when a predetermined time has elapsed from (A) and the first functional ink is in a first decolored state (substantially transparent). (C) is a top view which shows typically the mode of the information display medium after adding heating operation to (B). (A)-(C) are the figures which show the modification of the information display medium of Embodiment 1. FIG. FIG. 9 is a cut end view of the base, schematically showing a state in which the second functional ink is printed outside the print area of the first functional ink, showing a modification of the information display medium of Embodiment 1. FIG. 6 is a schematic diagram schematically illustrating a configuration of a printing apparatus provided for explanation of a printing apparatus and a printing method according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Information display medium 12 Ground 12a 1st main surface 14 1st functional ink 16 2nd functional ink 17 Non-information display area 18 Information display area 50 Printing device 52 1st printing part 54 2nd printing part 56 Printing means 54a, 56a Ink tanks 54b and 56b Print head 58 Coloring means

Claims (13)

By changing the colors from the first and second coloring states to the transparent first and second decoloring states over time, and by applying physical operations common to the first and second functional inks. The information is displayed on the ground using the first and second functional inks that change colors from the first and second decoloring states to the first and second coloring states, respectively.
The colors of the first and second functional inks in the first and second coloring states are visually indistinguishable from each other, and the first and second decoloring states are in the first and second decoloring states. The colors of the first and second functional inks are visually indistinguishable from each other,
Wherein the surface area of the base, information display regions are al provided,
Wherein the first functional ink, in the information display area, the provided first colored state, and the second functional ink, area on the base including the information display area, the first 2. An information display medium that is applied in a decolored state and is superimposed on the first functional ink in the information display area .   The information display medium according to claim 1, wherein the base is paper.   The information display medium according to claim 1, wherein the first and second functional inks are heat-sensitive inks, and the physical operation is heating.   4. The information display medium according to claim 3, wherein the first and second functional inks contain a leuco dye and a developer as main components. Before Stories second functional ink, when each of the first and second functional ink of the first and second decolorized state, in regular or irregular patterns can be prevented readability of the information the information display medium according to claim 1, characterized in that it is applied in the information display area. By changing the colors from the first and second coloring states to the transparent first and second decoloring states over time, and by applying physical operations common to the first and second functional inks. A printing apparatus for printing information on a base using the first and second functional inks that change colors from the first and second decoloring states to the first and second coloring states, respectively. ,
The colors of the first and second functional inks in the first and second coloring states are visually indistinguishable from each other, and the first and second decoloring states are in the first and second decoloring states. The colors of the first and second functional inks are visually indistinguishable from each other,
A first printing unit that prints the first functional ink in the first color development state in the information display area partitioned by the surface area of the base;
A printing apparatus comprising: a second printing unit that applies the second functional ink in the second decolored state to an area on the base including the information display area. The first printing unit includes a printing unit that prints the first functional ink in the first erasing state, and a coloring unit that changes the printed first functional ink into the first coloring state. The printing apparatus according to claim 6 , further comprising: 8. The printing apparatus according to claim 7 , wherein the first and second functional inks are heat-sensitive inks, and the color developing unit is a heating unit. The printing apparatus according to claim 8, further comprising a cooling unit that cools the first functional ink to a temperature lower than a coloring temperature between the first and second printing units. By changing the colors from the first and second coloring states to the transparent first and second decoloring states over time, and by applying physical operations common to the first and second functional inks. A printing method for printing information on a base using the first and second functional inks that change colors from the first and second decoloring states to the first and second coloring states, respectively. ,
The colors of the first and second functional inks in the first and second coloring states are visually indistinguishable from each other, and the first and second decoloring states are in the first and second decoloring states. The colors of the first and second functional inks are visually indistinguishable from each other,
A first printing step in which the first functional ink is printed and provided in the first coloring state in the information display area partitioned into the surface area of the base;
And a second printing step of applying the second functional ink in the second decolored state to an area including the information display area. The first printing step includes a printing sub-step for printing the first functional ink in the first decoloring state, and a coloring sub-step for changing the printed first functional ink to the first coloring state. The printing method according to claim 10 , further comprising: The printing method according to claim 11 , wherein a heat-sensitive ink is used as the first and second functional inks, and the printed first functional ink is heated in the coloring sub-step. The printing method according to claim 12, further comprising a cooling step of cooling the first functional ink to a temperature lower than a coloring temperature between the first and second printing steps.

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