JPH11192737A - Method and apparatus for printing and erasing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To repeatedly and stably obtain a developed color image by using a color developing and erasing type recording medium. SOLUTION: In a printing/erasing method performing the rewriting of a printed recording medium with respect to a reversible thermal recording medium having a recording layer containing a leuco dye and a coupler and reversibly developing and erasing a color according to heating temp. and/or a cooling speed after heating in the order of an erasing process and a printing process, the recording layer of a strip like range with a width of 1.2-5.0 mm is heated to erasing temp. in the erasing process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing method for a reversible thermosensitive recording medium having a recording layer capable of reversibly forming a color-developing state and a decoloring state by controlling thermal energy and capable of repeatedly printing and erasing. The present invention relates to an erasing method and apparatus.

[0002]

2. Description of the Related Art A conventional hard copy is used to form an image by adhering and fixing a colorant such as ink or toner to a recording medium such as paper from the outside, or a base material such as paper such as thermosensitive recording paper. A permanent image was formed by providing a recording layer thereon and applying energy to form a visible image. However, recently, the spread of copiers and facsimile machines,
The output of information from a computer causes a rapid increase in the consumption of recording media, causing social problems such as destruction of nature and waste disposal. In order to solve this problem, a recording material which can erase a recorded visible image and can be used repeatedly has been attracting attention. For example, there is a recording medium capable of reversibly forming two states, transparent and cloudy, by utilizing a change in the light scattering property of a polymer film in which low-molecular organic crystal particles such as fatty acids are dispersed (for example, Japanese Patent Application Laid-Open No. 55-154198). Such). This recording medium has already been put to practical use as a content display section of a magnetic card. However, the displayed image is printed in white on a black or blue colored background or a light-reflective background such as an aluminum vapor-deposited film, so that it is not suitable for a normal hard copy.

To solve this problem, there has been proposed a thermosensitive recording medium capable of reversibly forming a color-printed image on a white background using a leuco dye capable of taking two states of color development and color erasure (for example, Japanese Patent Application Laid-Open No. 5-124360). issue). The coloring and decoloring of this recording medium is controlled by the heating temperature and the cooling rate after heating, and the leuco dye contained in the recording layer and the developer for coloring this are formed to form the colored state. After the temperature is raised to the temperature for melting and mixing, the color is formed by rapid cooling. Slow cooling does not provide sufficient color density. Also,
Decoloring occurs when heated to a temperature slightly lower than the coloring temperature.

However, the recording / erasing type recording medium cannot be printed unless it is rapidly cooled after being heated, and when the recording medium is used repeatedly, it is erased and immediately printed. If the recording medium is heated by the heating at the time of erasure, the printed portion is not rapidly cooled but is gradually cooled, so that a sufficient color density cannot be obtained. Therefore, for rewriting, for example, it is necessary to cool the recording medium by some method between erasing and printing, but it is not practical to simply cool the recording medium for a long time because the processing time becomes long. There is also a method of cooling the recording medium by contacting it with a metal plate or the like after erasing.However, if the temperature of the entire recording medium including the base material as well as the recording layer increases, the temperature of the metal plate gradually increases, A sufficient cooling effect cannot be obtained. For this reason, the color density is not stable due to the frequency of the rewriting process and the environmental temperature.

In addition, since the coloring / erasing type recording medium has a higher decoloring temperature than that of a conventional transparent / opaque type recording medium, the base material of the recording medium is deformed by heating with a hot stamp or the like. Insufficient or poor conveyance will occur. In addition, when the entire surface is heated by date and time such as hot stamping, the time from heating to printing greatly differs between near the leading edge and the trailing edge of the recording medium, resulting in a difference in the recording medium temperature during printing. A homogeneous record cannot be obtained.

Further, the following drawbacks have been pointed out in the conventional heating means (heating bar). That is, if the surface smoothness is poor, the recording medium is repeatedly scraped due to printing and running, and scum adheres to the heating bar, thereby lowering the erasing efficiency and the heating efficiency. Poor conveyance due to collision of the recording medium with the corner of the heating bar The scraping of the recording medium due to the rubbing of the corner of the heating bar occurs, and there is a decrease in the erasing efficiency due to the attachment of the shavings to the heated surface.

[0007]

As described above, the color-decoloring / decoloring type recording medium using a leuco dye has a property that a sufficient color density cannot be obtained unless the recording layer in the printed portion is rapidly cooled. Therefore, there is a problem that the processing time required for rewriting becomes long. In addition, there is a problem that a stable color image cannot be obtained even if a mechanism for cooling by making contact with a metal plate or the like after erasing is used. Furthermore, there has been a problem that no satisfactory heating means has been proposed.
An object of the present invention is to solve the problems of the conventional printing / erasing method and apparatus using such a reversible thermosensitive medium, to shorten the rewriting processing time, and to obtain printing / erasing in which printing with high color density can be obtained stably. Methods and apparatus are provided.

[0008]

According to the present invention, first, a recording layer containing at least a leuco dye and a developer is provided, and the recording layer is reversibly reversible by a difference in heating temperature and / or cooling rate after heating. For the reversible thermosensitive recording medium to be colored and decolored, rewriting of the printed recording medium is performed by an erasing step,
In the printing / erasing method performed in the order of the printing step, there is provided a printing / erasing method characterized in that the erasing step heats a recording layer in a band-like range having a width of 1.2 to 5.0 mm to an erasing temperature.

Second, printing is performed on a reversible thermosensitive recording medium which has a recording layer containing at least a leuco dye and a color developer, and which reversibly develops and decolors at a heating temperature and / or a cooling rate after heating. In the printing / erasing method in which the rewritten recording medium is rewritten in the order of the erasing step, the preheating step, and the printing step, the erasing step heats the recording layer in a band-like range having a width of 1.2 to 5.0 mm to the erasing temperature. A printing / erasing method is provided.

Third, a reversible thermosensitive recording medium which has a recording layer containing at least a leuco dye and a color developer and reversibly develops and decolors depending on a difference in heating temperature and / or cooling rate after heating. In a printing / erasing method in which rewriting of a printed recording medium is performed in the order of a preheating step also serving as an erasing step and a printing step, the erasing step has a width of 1.2 to 1.2.
A printing / erasing method is provided in which a recording layer in a 5.0 mm band is heated to an erasing temperature.

Fourthly, a reversible thermosensitive recording medium which has a recording layer containing at least a leuco dye and a color developer and reversibly develops and decolors depending on a difference in a heating temperature and / or a cooling rate after heating. In a printing / erasing method in which rewriting of a printed recording medium is performed in the order of an erasing step, a cooling step, and a printing step, the erasing step sets a band-shaped recording layer having a width of 1.2 to 5.0 mm to an erasing temperature. A printing / erasing method characterized by heating is provided.

Fifth, a reversible thermosensitive recording medium which has a recording layer containing at least a leuco dye and a color developer and reversibly develops and decolors depending on a difference in a heating temperature and / or a cooling rate after heating. In a printing / erasing method in which rewriting of a printed recording medium is performed in the order of an erasing step, a cooling step, a preheating step, and a printing step, the erasing step has a width of 1.2 to
A printing / erasing method is provided in which a recording layer in a 5.0 mm band is heated to an erasing temperature.

Sixth, a reversible thermosensitive recording medium which has a recording layer containing at least a leuco dye and a color developer and reversibly develops and decolors depending on a difference in a heating temperature and / or a cooling rate after heating. In a printing / erasing method in which rewriting of a printed recording medium is performed in the order of a pre-heating step, a cooling step, and a printing step also serving as an erasing step, the erasing step has a width of 1.2 to 5.0 mm. A printing / erasing method is provided, wherein the recording layer is heated to an erasing temperature.

Seventh, in any of the first to sixth printing / erasing methods, the surface of the recording medium is brought into contact with a heating member having a fixed erasing step, and the recording medium is heated while heating the belt-shaped area. A printing / erasing method characterized by being transported is provided. Eighth, in any one of the fourth to seventh printing / erasing methods, the recording medium heated in the erasing step may be cooled by bringing a cooling member into contact with at least the surface of the recording medium in a stationary state. Characterized by printing
An erasure method is provided. Ninth, in any of the fourth to seventh printing / erasing methods described above, while conveying the recording medium heated in the erasing step, cooling is performed by bringing a cooling member into contact with at least the surface of the recording medium. And a printing / erasing method is provided.

Tenth, in any of the fourth to ninth printing / erasing methods described above, the temperature of the recording medium heated and conveyed in the erasing step is detected, and the recording medium is cooled according to the temperature of the recording medium. There is provided a printing / erasing method characterized by controlling a contact time with a member. Eleventh, the fourth to the above
In any one of the ninth printing and erasing methods, the recording medium heated in the erasing step is brought into contact with a cooling member, the temperature of the cooling member is detected, and the temperature of the recording medium and the cooling member is changed according to the temperature of the cooling member. A printing / erasing method characterized by controlling a contact time is provided. Twelfthly, in any of the fourth to ninth printing / erasing methods, the temperature of the recording medium and / or the temperature of the cooling member which is heated in the erasing step and subsequently cooled by the cooling member is detected. There is provided a printing / erasing method characterized by controlling a contact time between a recording medium and a cooling member according to a temperature.

Thirteenth, in any of the fourth to ninth printing / erasing methods described above, the temperature of the recording medium heated in the erasing step and subsequently cooled by the cooling member and / or the temperature of the cooling member is detected. And controlling the contact time between the recording medium and the cooling member in accordance with the temperature, and providing a printing / erasing method characterized in that the cooling control is performed by changing the conveyance speed of the recording medium. .

Fourteenthly, in any of the fourth to ninth printing / erasing methods, the temperature of the recording medium heated in the erasing step and subsequently cooled by the cooling member and / or the temperature of the cooling member is detected. The printing / erasing method is characterized by controlling the contact time between the recording medium and the cooling member according to the temperature, and performing this cooling control by changing the number of times of contact between the recording medium and the cooling member. Provided. Fifteenth, in any of the second, third and fifth to fourteenth printing / erasing methods described above, the pre-heating step comprises: The printing / erasing method is characterized in that the heating is performed uniformly so that

According to the present invention, in a sixteenth aspect, a reversible thermosensitive recording medium having a recording layer containing at least a leuco dye and a developer is reversibly heated by a difference in heating temperature and / or cooling rate after heating. Erasing means for heating the recording layer to an erasing temperature, printing means for printing on the erased recording layer using a thermal head, erasing means for the recording medium, and printing. A heating member for heating the erasing means in contact with the surface of the recording medium, and a conveying mechanism for conveying the recording medium in contact with the heating member. The width of the heating element is 1.2 to 5.0 in the recording medium transport direction.
mm is provided.

Seventeenth, in the sixteenth printing / erasing apparatus, the recording medium may be set between the erasing means and the printing means such that the temperature of the recording medium is 40 ° C. or lower, which is lower than the erasing lower limit temperature specific to the recording medium. A printing / erasing device provided with a preheating means for uniformly heating is provided. Eighteenthly, there is provided a printing / erasing apparatus according to the sixteenth or seventeenth aspect, wherein the erasing means also serves as a preheating means.

Nineteenthly, in the sixteenth printing / erasing apparatus, a cooling means for cooling the recording medium heated in the erasing step is provided between the erasing means and the printing means. Is provided. Twentieth, in the printing / erasing apparatus of the seventeenth or eighteenth aspect, a cooling means for cooling the recording medium heated in the erasing step is provided between the erasing means and the preliminary heating means. A printing / erasing device characterized by the above features is provided. Twenty-first, in any one of the 16th to 20th printing / erasing device,
A printing / erasing apparatus is provided, wherein a cooling means is provided between the erasing means also serving as a preheating means and the printing means.

Twenty-second, in the printing / erasing apparatus according to any one of the sixteenth to twenty-first aspects, the temperature of the recording medium inserted in the apparatus is detected to control the temperature of the ceramic heater. A printing / erasing device is provided. Twenty-third, in the printing / erasing device according to any one of the sixteenth to twenty-second, the temperature of the recording medium inserted into the device is detected to control the contact time between the ceramic heater and the recording medium. A printing / erasing device is provided.
In the twenty-fourth, any one of the 16th to 23rd printing
In the erasing device, there is provided a printing / erasing device characterized in that a thermal head of the printing means also serves as the erasing means.

In the printing / erasing apparatus according to any one of the sixteenth to twenty-fourth aspects, the cooling means may be such that the cooling means contacts at least the surface of the recording medium heated by the erasing means and cools the cooling medium. Wherein the cooling member is a metal plate, a metal block, or a metal roller. In a twenty-sixth aspect, there is provided a printing / erasing apparatus according to any one of the sixteenth to twenty-fifth aspects, wherein the cooling member of the cooling means has a heat dissipation structure. Twenty-seventh, in the printing / erasing apparatus according to any one of the sixteenth to twenty-sixth aspects, in addition to the erasing means, the cooling means, the printing means, and the transporting means, further comprising an air cooling means. A printing / erasing device is provided.

In the printing / erasing apparatus according to any one of the sixteenth to twenty-seventh aspects, the heating member constituting the erasing means has a width of 1.2 to 5.0 mm on the ceramic substrate. A printing / erasing device is provided, which has a band-shaped heating resistor and is covered with a glass protective layer. 29. In the printing / erasing apparatus according to any one of the 16th to 28th, the edge R (chamfer) of the heating member in the recording medium moving direction is 0.01 to 1 mm. Is provided. Thirty, a printing / erasing apparatus according to any one of the sixteenth to twenty-ninth aspects, wherein the heating member has a surface roughness Rz of 0.01 to 1 μm. Is done.

Thirty-first, in the printing / erasing apparatus according to any one of the sixteenth to thirtyth aspects, when the leading end of the printing portion of the recording medium reaches the ceramic heater position of the erasing means, the platen roll is moved to the recording medium. And the pressure is released when the rear end of the printing section reaches the ceramic heater position of the erasing means. 32ndly, in the printing / erasing apparatus according to any one of the 16th to 31st, the transport speed of the recording medium by the platen in the erasing means is lower than the speed at which the recording medium enters the platen. A printing / erasing device characterized by the above features is provided. 33. In the printing / erasing apparatus according to any one of the 16th to 32nd, the unloading speed of the recording medium by the unloading roller pair in the erasing means is lower than the transport speed of the recording medium by the platen. And a printing / erasing device characterized by the following.

In the present invention, the preheating (hereinafter, sometimes referred to as pre-printing heating) refers to heating uniformly below the coloring temperature. More preferably, as described above, the erasing lower limit inherent to the recording medium. That is, heating is performed uniformly so that the temperature becomes 40 ° C. or lower. According to the printing / erasing method and apparatus of the present invention, in a rewriting process of a recording medium having a reversible color recording layer containing a leuco dye and a color developing material, a relatively narrow portion including the recording layer is heated and recorded. Since the medium is not heated unnecessarily, the recording medium can be easily cooled. Further, according to the present invention, since the recording medium can be easily cooled to a certain level, the temperature of the recording medium in the printing process can be stabilized. As a result, the printed portion is always cooled rapidly, so that printing with a high color density can be stably obtained, and the rewriting process can be performed quickly.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. As shown in FIG. 1, a recording medium 11 used in the present invention
Is a support 12 made of plastic, paper, synthetic paper, or the like.
And a transparent protective layer 14 for preventing the recording layer from deteriorating. In addition, if necessary, an adhesive layer (preventing peeling) between the support and the recording layer, an intermediate layer (preventing ultraviolet rays) between the recording layer and the protective layer, a colored printing ink layer on a part of the protective layer, In some cases, a transparent protective layer is provided to improve the surface transportability including the ink layer portion and the cleaning performance. The reversible thermosensitive recording layer 13 is formed by dispersing a leuco dye and a developer in a resin binder.

The leuco dye used in the recording layer is a known dye precursor such as a phthalide compound, an azaphthalide compound, a fluoran compound, a phenothiazine compound or a leuco auramine compound. Specifically, known leuco dyes described in JP-A-05-124360 can be used. The developer used in the recording layer has a structure having a color developing ability to develop a leuco dye in a molecule, for example, a phenolic hydroxyl group, a carboxylic acid group, a phosphoric acid group, and a structure controlling the cohesive force between molecules, for example, A compound having a structure in which long-chain hydrocarbon groups are linked. The linking part may be via a divalent group containing a hetero atom, or the long chain hydrocarbon group may contain a divalent group containing a hetero atom or an aromatic group. Specifically, Japanese Patent Application Laid-Open
Known developers described in, for example, JP-A-124360 can be used. The support 12 is magnetic, optical memory, magneto-optical, I
A C memory may be provided. Further, the recording medium 11 may have another thermosensitive recording layer and a reversible thermosensitive recording.

A recording medium using such a leuco dye and a developer develops and decolors in the process shown in FIG. Heating the initial colorless state (A) the temperature above T ₁ in leuco dye and the developer are colored by mixing and melting (B), it remains fixed in the colored state and quenching the state (C). As the coloring state (C) is heated, a temperature T ₂ lower than the coloring temperature T ₁ is obtained.
(D), and when cooled, the same decolored state as the initial state is obtained. Here, if the cooling from the molten color developing state (B) is gradually cooled, the concentration decreases in the course of the temperature drop, and in an extreme case, the color is almost completely erased.

The color density obtained in this way depends on the cooling speed, and an intermediate color development state in which the density is reduced is produced under the condition that the temperature is gradually cooled to some extent. This characteristic is obtained by utilizing the fact that the molecular assembly state in which the leuco dye interacts with the color developer is fixed by rapid cooling, and the decoloration utilizes the phase separation between the leuco dye and the color developer. Because it is. Under gradual cooling conditions, the color density is reduced because phase separation occurs during the cooling process. As mentioned above, the transparent / opaque recording medium differs from the coloring / erasing type recording medium to which the present invention is applied in this respect, and depends only on the heating temperature and not on the cooling rate. Therefore, the problem that printing must be heated and quenched is unique to this coloring / decoloring type recording medium, and the present invention is a printing / erasing method and apparatus that solves this problem.

The thermal recording medium is usually printed using a thermal head. In this method, if the recording medium is at room temperature, the heating time is as short as about milliseconds and the heating range is narrow. Quickly diffuses, substantially quenching conditions can be realized. Therefore, when only printing is performed, printing with a high density can be performed as long as the energy required for melting and coloring is given. However, the reversible thermosensitive recording medium is usually used to erase the color image already printed, and then perform another printing and rewrite.
The erasing step and the printing step are performed continuously. In the erasing step, the recording medium is heated to the erasing temperature.

In order to perform such heating, conventionally, FIG.
The erasing means 91 shown in FIG. This is a method in which a heating member 92, for example, a metal plate or a metal block, which is controlled to an erasing temperature by a heating resistor, is pressed against the entire portion of the recording medium 34 to be erased by a pressing member 94 having an elastic member 93 (hot stamping method). It is. Since hot stamp erasing erases the print surface of the recording medium all at once, the recording medium including the base material is heated over a wide range. Therefore, since the substrate is heated above the softening point,
Deformation and shrinkage occur, impairing the function of the recording medium.

In the erasing step of the present invention, heating is performed. The heating member is provided at a position in contact with the recording medium surface. As shown in FIGS. 5 and 6, the erasing platen roller 5 having a transport function is located at a position facing the heating member 51.
5, the heating member 51 sandwiches the recording medium 34 and presses the recording medium 34 against the platen roller 55 with a constant pressure. The heating member 51 may be fixed at a position where the recording medium is conveyed and at least the printing surface to be erased is in contact with the surface of the recording medium when the printing surface to be erased is at the platen roller position. There may be. According to such an erasing means, since the recording medium 34 moves and comes into contact with the heating member 51 to erase the printing surface, it is not necessary to heat the front surface of the printing surface all at once, and a relatively narrow portion can be heated. become. If the narrow portion is heated for a short time, the temperature of the base material of the recording medium does not rise so much, and only the recording layer can be efficiently brought to the erasing temperature. Therefore, the diffusion of heat in the heated portion after erasure is likely to occur,
The temperature can be easily lowered.

As described above, the recording layer is heated for the time required for erasing, the recording layer is efficiently heated, unnecessary portions are not heated as much as possible, and the width of the recording layer reaching the erasing temperature is made as narrow as possible. It is important to.
Since a substantial recording medium can be erased by heating for 1 second or less,
The contact with the heating member is performed for 1 second or less, preferably 0.1 to 1 second. By bringing the heating member into contact with the surface on the recording layer side, only the recording layer of the recording medium can be effectively heated. Also, by making the width of the heating member narrow in the recording medium conveyance direction and making the contact portion with the recording medium into a band shape having a width of 1.2 to 5 mm, effective cooling after heating becomes possible.

In practice, a plurality of lines of characters, for example, are printed on a recording medium, and a large area is generally used. If the character has a width of 5 mm or less, it can be erased by contacting the heating member having the above width line by line. However, it is not efficient to erase prints over a plurality of lines, so the recording medium is conveyed while being in contact with a fixed heating member having a width of 1.2 to 5.0 mm.
It is preferable to heat the entire portion to be erased while moving the belt-shaped heating portion. This can be achieved by the heating means of the above-mentioned heating and conveying system. In this case, the heating time is preferably such that the time during which the recording medium is in contact with a certain point on the recording medium is calculated from the transport speed and the width of the heating member, and the time is set to 1 second or less. The width of the heated part is 1.2 ~
5.0 mm is preferable, and if it is narrower, the transport speed must be reduced to secure a constant erasing time. When the width of the contact portion is reduced in this manner, uniformity of contact between the recording medium 34 and the heating member 51 is easily obtained, and the recording layer is uniformly heated to the erasing temperature. Are also obtained at the same time. In addition, the width of the contact portion with the recording medium does not match the width of the heating member,
It changes depending on the degree of elasticity of the platen roller and the pressing force.

FIG. 7 shows a state in which the entire recording layer of the recording medium 34 is erased and erased, and then heated before printing (preliminary heating), and subsequently printing is performed. This preheating is performed at a temperature not higher than the temperature at which the recording medium develops color. Preferably, the preheating is performed by uniformly heating the recording medium so as to have a temperature not lower than the erasing lower limit temperature inherent to the recording medium and not lower than 40 ° C. FIG. 8 shows a case where the recording medium is cooled after the heating for erasing is obtained and before the preliminary heating. FIG. 9 shows an example in which preliminary heating is also used for heating in the erasing step. FIG. 10 shows an example in which cooling means is provided between the erasing means and the printing means. As the cooling means, a Peltier element or the like is used in addition to a cooling fan and a metal block. In the example of FIG. 10, the erasing means may also serve as preheating.

As the heating member, a so-called ceramic heater in which a thin-film heating resistor is provided in a strip shape on a ceramic substrate, and the heating resistor is covered with a glass protective layer, is particularly preferable. The ceramic heater has a good rise in temperature up to the erasing temperature, and cools quickly when power supply is stopped. Therefore, heating to the erasing temperature can be performed only when the recording medium is inserted and erasing is performed, and since the heat storage is small, the rise in the internal temperature can be suppressed. This has a positive effect on the efficiency and stability of the cooling after this heating. In addition, uniform heating is possible with high surface smoothness.

Therefore, the printing / erasing apparatus of the present invention is a printing / erasing apparatus having erasing means for heating and erasing a recording medium to an erasing temperature using a ceramic heater and printing means for printing using a thermal head. Yes, as shown in FIG.
A thin-film heating resistor 52 is provided in a strip shape on the top, and a heating layer 52 is covered with a glass protective layer 53. Heat is generated by an energizing pulse, and the set temperature is controlled by the sensor 57 as a basis. Preheating may be performed because it takes time to energize.
The width d of the strip-shaped heating resistor 52 is 1.2 to 5.0 mm. As mentioned above, if the value of d is smaller than 1.2 mm, the erasing function is poor, and the processing speed becomes slow, which is not practical. Conversely, if the value of d is larger than 5.0 mm, uniform temperature control cannot be performed, resulting in erasure unevenness.

The ceramic heater has a surface degree Rz of 1 μm.
m or less, preferably 0.01 to 1 μm. If Rz is larger than 1 μm, the recording medium may be displaced or dust may adhere to the ceramic heater and cause erasure failure. The edge R of the ceramic heater in the recording medium moving direction is preferably in the range of 0.01 to 1 mm. If R is smaller than 0.01 mm, the conveyance failure due to the collision with the corner, the recording medium is displaced by the influence of the edge, and the adhesion of dust increases, resulting in erasure failure. Conversely, if R is larger than 1 mm, the effective contact width becomes narrow. In the ceramic heater, it is desirable that the length W of the peaks and valleys of the undulation (undulating state) is 1 μm or less per 450 mm in length.

The platen roll of the ceramic heater preferably has a hardness D = 60-90. If the recording medium is softer than 60, the recording medium is difficult to be conveyed during the heat treatment. As the value becomes 90, the accuracy of the straightness of the roll is 1 mm or less, the roundness is 1 mm or less, and the deflection is 1 mm or less. The material of the platen roll is preferably plastic, rubber, metal, or the like, and may be subjected to a conductive treatment or a flocking treatment.
The pressing pressure of the ceramic heater 51 or the platen roll 56 on the recording medium is suitably 0.01 to ² kg / cm ² , and is usually performed by lowering or raising the ceramic heater. 0.01 kg / cm ² less than the uniform erasure can not be performed, the transport of 2 kg / cm ² is greater than the recording medium becomes difficult.

Whether the printing speed and the erasing speed of the recording medium are the same,
It is desirable to make the erasing speed lower. Since erasing heats the entire surface, the heating temperature is lower than the printing temperature, but it requires more applied energy than the printing section, so the transport speed of the erasing section must be slower than the transport speed of the printing section. This is because such a setting is desirable in practical use. Erasing speed (ν) is 10 to 40
mm / s is appropriate. If the speed is lower than 10 mm / s, it is not practical. As in the case of hot stamping, the base material is deformed. If the speed is higher than 40 mm / s, erasure cannot be performed. As shown in FIG. 5, it is desirable that the incident angle (α) of conveyance of the recording medium to the ceramic heater be 0 to 45 degrees. When the angle is less than 0 degree, the recording medium and the ceramic heater are hardly in contact with each other.

Further, in the printing / erasing method apparatus according to the present invention, when the erasing means reaches the ceramic heater position at the leading end of the printing portion of the recording medium, the ceramic heater 51 or the pteran roll 56 presses the recording medium into contact with the recording medium to perform printing. When the pressure reaches the rear end, the pressure is released, which results in efficient power consumption. Further, the print erasing device of the present invention may be a device that performs a plurality of erasures two or more times. Further, the print erasing device of the present invention may include two or more erasing means, which are arranged in series on the recording medium conveying path, and the recording medium may be heated a plurality of times. These can be processed at high speed by an efficient erasing method.

The printing and erasing apparatus of the present invention may perform the erasing process again if the recording medium after the erasing process detects an erasing afterimage equal to or greater than a specified value. Further, the print erasing device of the present invention performs the printing process immediately after the erasing process. Further, the print erasing device of the present invention detects the temperature of the recording medium inserted into the device by, for example, a thermistor, a thermocouple, or an infrared sensor. If the temperature is low, the ceramic heater temperature may be controlled to a high temperature or the contact time may be increased to control the temperature. In addition, the print erasing device of the present invention detects the temperature around the device using, for example, a thermistor, a thermocouple, or an infrared sensor.If the temperature is higher than the standard, the ceramic heater temperature is controlled to a low temperature or the contact time is shortened. The temperature of the ceramic heater may be controlled to a high temperature or the contact time may be lengthened for control. Further, the print erasing apparatus of the present invention may use the thermal head of the printing means as an aid to the erasing means. Also, the thermal head may also serve as the erasing means,
In that case, it is desirable to make the transport speed at the time of erasing slower than at the time of printing. Further, the thermal head may also serve as the calling heating means.

As shown in FIG. 6A, the printing / erasing apparatus according to the present invention carries in the recording medium at a speed lower than the entering speed of the recording medium (v _2).
<V ₁ ) is advantageous in that the card is slowed down, and when it is hit, the card is weakly deformed and the contact area can be increased. In addition, as shown in FIG. 6B, when the card is conveyed at a speed higher than the carry-out speed (v ₂ > v ₃ ), when the card is pinched by the pair of conveying rollers, a weak deformation occurs, and the contact area can be increased. It is advantageous.

Preferably, cooling means is employed. This includes a blower that contacts a recording medium and a cooling member, and blows cool air onto the recording medium. The case where the former cooling member is used will be described below. In the cooling section,
The cooling member is brought into contact with the recording medium conveyed by the conveying roller from the erasing section to cool the recording medium to a temperature at which printing is possible. The cooling member is preferably a plate, a block, a roller, or the like of a metal having good heat conductivity such as aluminum or copper from the viewpoint of improving cooling efficiency. The cooling member needs to be provided at least on the printing surface side of the recording medium. In order to improve heat dissipation from the recording medium, the recording medium needs to be pressed against the cooling member. As shown in FIG. 8, a pressing member 72 using a force such as a spring is provided at a position facing the cooling member 71. The pushing member 72 may be a plate-shaped member or a roller-shaped member. The recording medium is pressed against the cooling member, and is efficiently cooled.

In the cooling step, the recording medium may be stopped once at the position of the cooling member and pressed against the cooling member, or may be pressed against the cooling member while transporting the recording medium. In the former case, either the cooling member or the extruding member waits at an upper or lower distant position, and moves and inserts when the recording medium is conveyed and stopped. In the latter case as well, it is preferable that the cooling member be brought into contact when the print portion of the recording medium to be erased comes to the cooling member position, and otherwise, the cooling member stand by at a position away from the pushing member. In this case, it is preferable that the surface of the cooling member is coated with a material having high lubricity such as Teflon so as not to hinder heat conduction. In the printing / erasing apparatus of the present invention, since no extra heat is applied in the erasing step, the load on the cooling step is small, but when the frequency of rewriting printing increases, heat is stored in the cooling member. Therefore, it is preferable that the cooling member has a heat dissipating structure 73 (cooling fin) having a large contact area with air by a large number of thin metal plates having good heat conduction. Further, in order to create a flow in the air in contact with the cooling fins and enhance the heat radiation effect, it is preferable to provide a blower cooling mechanism.

In order to stably form a print having a sufficient color density in the printing process, the temperature of the recording medium after the erasing process must be maintained at a constant level after the cooling process. What is necessary is just to detect the temperature and control the contact time with the cooling member in the cooling step according to the temperature. A temperature detector 81 is installed between the erasing step and the cooling step, and if the detected recording medium temperature is higher than the standard setting temperature, the contact time with the cooling member is lengthened, and if the detected temperature is low, the temperature is shortened. Thus, the temperature after the cooling step can be kept at a constant level. For the temperature detection, for example, a contact-type temperature detector such as a thermistor or a thermocouple, or a non-contact-type detector for detecting infrared rays from a recording medium may be used.

To further stabilize the temperature of the cooling step,
A temperature detector 82 may be provided on the cooling member to detect the temperature of the cooling member and control the contact time between the recording medium and the cooling member accordingly. If the temperature of the cooling member when the recording medium reaches the cooling member position is controlled to increase the contact time when the temperature is higher than the standard set temperature and to shorten the contact time when the temperature is low,
The temperature after the cooling step can be kept at a constant level. For the temperature detection, a thermistor or a thermocouple may be provided in contact with the cooling member 71.

To further stabilize the temperature after cooling, control of the contact time by detecting the recording medium after the above-mentioned erasing step,
The contact time control based on the detection of the cooling member temperature may be used in combination. Accordingly, the recording medium temperature during printing can always be adjusted to a constant level, so that printing with high color density can be stably obtained. The control of the contact time with the cooling member may be performed by changing the transfer speed or increasing or decreasing the number of times of contact with the cooling member even when the transfer speed is the same.

The printing means 42 comprises a thermal head 46 and a platen roller 47, and performs new printing on the recording medium conveyed from the erasing step, the cooling step or the preheating step. Since the recording medium is cooled to a level sufficient to rapidly cool the printed portion, printing with a stable density is always performed. The rewritten recording medium is discharged by the discharge roller 45.

[0050]

Next, an example in which the printing / erasing step of the present invention is applied to a card-type coloring / erasing recording medium having a size of 54 mm in length and 54 mm in width will be described. First, only the printing process was performed on the recording medium with sufficient energy without using the erasing means and the cooling means. As a result, the print density was 1.25, which was sufficient for the background density of 0.10. A good print image with high visibility was obtained. The recording medium has a black color. Next, using a printing and erasing device installed so as to continuously perform erasing means and printing means having a heating member of an aluminum block large enough to heat half the area of the recording medium at a time for comparison, Was rewritten and printed. The erasing conditions are 120 ° C. for 1 second, and the interval from erasing to printing is about 1 second. As a result, the previously printed portion became completely the same as the background density and was erased, and another pattern was newly printed. However, the print density was much lower than the initial print, with a density of 0.65. In order to obtain the same level of density as that of the apparatus, it was necessary to temporarily stop between erasing and printing, and to take an interval of about 12 seconds.

Subsequently, a cooling means was provided between the erasing means and the printing means of the printing / erasing apparatus. The cooling member of the cooling means is an aluminum block having a width of 30 mm and a thickness of 0.5 m.
It has 10 cooling fins made of an aluminum plate of m.
In the cooling step, the recording medium printing surface is conveyed at a speed of 20 mm / sec while contacting the cooling member. When a rewriting process was performed using this apparatus, a printed image having a color density of 0.82 was obtained. However, in order to obtain an image having a sufficient contrast, the transport speed had to be 10 mm / sec.

Next, in the apparatus having the above-mentioned erasing means, cooling means, and printing means, only the erasing means was changed, and the heating member was a ceramic heater having a strip-shaped heating resistor having a width of 5 mm, and the temperature was set to 125 ° C. The width of the contact portion between the ceramic heater and the recording medium was 3.5 mm. A recording medium that has been printed in advance is inserted, and the erasing step is carried out at a speed of 30 mm / sec while being conveyed at a speed of 30 mm / sec to make contact with the heating member for erasing. In addition, thermal head printing was performed in the printing process.
The first print was completely erased, and the newly formed print had sufficient visibility at a color density of 1.10.

Next, the width of the heating resistor of the ceramic heater of the erasing means is set to 2 m in the printing / erasing apparatus of the present invention.
m, and the width of the contact portion with the recording medium was 1.2 mm. When the heater temperature is set to 125 ° C. and the conveying speed is set to 20 mm / sec through the erasing process, the first print can be completely erased,
A color density of 1.22 was obtained. This is almost the same density as when only printing is performed with sufficient energy.

[0054]

According to the printing and erasing method and apparatus of the present invention, a high-density printed image can be stably obtained in rewriting a coloring / erasing type recording medium, and the rewriting processing time can be shortened. can do. In addition, there is almost no deformation of the recording medium, and the image erasing efficiency is good.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of a color-developing / erasing type recording medium according to an embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating a color developing / erasing process of a color developing / erasing type recording medium according to an embodiment of the present invention.

FIG. 3 is a diagram schematically showing a configuration of a hot stamp type erasing means.

FIG. 4 shows a positional relationship between a heating member (ceramic heater) and a heating resistor used in the present invention.
Is a bottom view, (b) is a right top view, and (c) is a side view.

FIG. 5 is a diagram illustrating a state in which a card-shaped recording medium is transported between a ceramic heater and a platen roll.

FIGS. 6A and 6B are diagrams showing a state in which a card-shaped recording medium is transported between a ceramic heater and a platen roll.

FIG. 7 is a diagram schematically illustrating a configuration of a printing / erasing apparatus according to an embodiment of the present invention.

FIG. 8 is a diagram schematically illustrating a configuration of a printing / erasing device according to an embodiment of the present invention.

FIG. 9 is a diagram schematically illustrating a configuration of a printing / erasing device according to an embodiment of the present invention.

FIG. 10 is a diagram schematically illustrating a configuration of a printing / erasing apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 11 Color-decoloring type recording medium 12 Base material 13 Recording layer 14 Protective layer 31 Erasing means 32 Preheating means 34 Recording medium 42 Printing means 43 Supply roller 44 Transport roller 45 Discharge roller 51 Heating member 55 Platen roller 52 Heating resistor 53 Glass Protective layer 54 Ceramic substrate 56 Platen roller 57 Sensor 58 Ceramic heater 71, 71 'Cooling member 72 Cooling pressing member 73 Heat dissipation structure 81 Recording medium temperature detector 82 Cooling member temperature detector 91 Erasing means 92 Heating member 93 Elastic member 94 Pressing member

Continued on the front page (72) Inventor Fumio Kawamura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Kyoji Tsutsui 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Masafumi Torii 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Masaru Shimada 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Invention Person Hiroaki Matsui 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (33)

[Claims] 1. A reversible thermosensitive recording medium having a recording layer containing at least a leuco dye and a color developer and reversibly developing and erasing colors depending on a difference in a heating temperature and / or a cooling rate after heating. In the printing / erasing method of performing the rewriting of the recording medium in the order of the erasing step and the printing step,
A printing / erasing method, wherein the erasing step heats a recording layer in a band-like range having a width of 1.2 to 5.0 mm to an erasing temperature. 2. A reversible thermosensitive recording medium which has a recording layer containing at least a leuco dye and a color developer and which reversibly develops and decolors at a heating temperature and / or a cooling rate after heating. In a printing / erasing method in which rewriting of a recording medium is performed in the order of an erasing step, a preheating step, and a printing step, the erasing step heats a recording layer in a band-like range having a width of 1.2 to 5.0 mm to an erasing temperature. A printing / erasing method characterized by the following. 3. A printing method on a reversible thermosensitive recording medium having a recording layer containing at least a leuco dye and a color developer, and reversibly developing and erasing colors depending on a difference in heating temperature and / or cooling rate after heating. In the printing / erasing method in which the rewriting of the recorded recording medium is performed in the order of the preheating step also serving as the erasing step and the printing step, the erasing step has a width of 1.2 to 5.0 m.
A printing / erasing method comprising heating a recording layer in a band-like range of m to an erasing temperature. 4. A reversible thermosensitive recording medium which has a recording layer containing at least a leuco dye and a color developer and reversibly develops and decolors depending on a difference in heating temperature and / or cooling rate after heating. In the printing / erasing method of rewriting the recorded recording medium in the order of an erasing step, a cooling step, and a printing step, the erasing step heats a recording layer in a band-like range having a width of 1.2 to 5.0 mm to an erasing temperature. A printing / erasing method characterized by the following. 5. A reversible thermosensitive recording medium having a recording layer containing at least a leuco dye and a color developer and reversibly developing and erasing colors depending on a difference in heating temperature and / or cooling rate after heating. In a printing / erasing method in which the rewritten recording medium is rewritten in the order of an erasing step, a cooling step, a preheating step, and a printing step, the erasing step has a width of 1.2 to 5.0.
A printing / erasing method comprising heating a recording layer in a strip-shaped range of mm to an erasing temperature. 6. A printing method for a reversible thermosensitive recording medium having a recording layer containing at least a leuco dye and a color developing agent and reversibly developing and erasing colors depending on a difference in heating temperature and / or cooling rate after heating. In the printing / erasing method in which the rewriting of the recorded recording medium is performed in the order of the preheating step, the cooling step, and the printing step also serving as the erasing step, the erasing step has a width of 1.2.
A printing / erasing method comprising heating a recording layer in a band-like range of up to 5.0 mm to an erasing temperature. 7. The recording medium according to claim 1, wherein the surface of the recording medium is brought into contact with the heating member to which the erasing step is fixed, and the recording medium is conveyed while heating the belt-shaped area. Printing / erasing method. 8. The recording medium according to claim 4, wherein the recording medium heated in the erasing step is cooled by bringing a cooling member into contact with at least the surface of the recording medium in a stationary state. Printing / erasing method. 9. The recording medium heated in the erasing step, while being conveyed, is cooled by bringing a cooling member into contact with at least the surface of the recording medium.
The printing / erasing method according to any one of the above. 10. The temperature of a recording medium heated and conveyed in an erasing step is detected, and a contact time between the recording medium and a cooling member is controlled according to the temperature of the recording medium. The printing / erasing method according to any one of the above. 11. A method in which a recording medium heated in an erasing step is brought into contact with a cooling member, a temperature of the cooling member is detected, and a contact time between the recording medium and the cooling member is controlled in accordance with the temperature of the cooling member. The printing / erasing method according to any one of claims 4 to 9, wherein: 12. A temperature of a recording medium which is heated in an erasing step and subsequently cooled by a cooling member and / or a temperature of the cooling member, and a contact time between the recording medium and the cooling member is controlled in accordance with the detected temperature. The printing / erasing method according to any one of claims 4 to 9, wherein: 13. A temperature of a recording medium heated in an erasing step and subsequently cooled by a cooling member and / or a temperature of the cooling member, and a contact time between the recording medium and the cooling member is controlled in accordance with the detected temperature. The printing / erasing method according to any one of claims 4 to 9, wherein the cooling control is performed by changing a conveyance speed of the recording medium. 14. A temperature of a recording medium heated in an erasing step and subsequently cooled by a cooling member and / or a temperature of the cooling member, and a contact time between the recording medium and the cooling member is controlled according to the detected temperature. 10. The printing / erasing method according to claim 4, wherein the cooling control is performed by changing the number of times of contact between the recording medium and the cooling member. 15. The preheating step in which the recording medium is uniformly heated so that the temperature of the recording medium is equal to or lower than the erasing lower limit temperature of the recording medium and equal to or higher than 40 ° C. 15. The printing / erasing method according to any one of 5 to 14. 16. A reversible thermosensitive recording medium having a recording layer containing at least a leuco dye and a developer,
Or, a device for reversibly developing and erasing colors according to the difference in cooling rate after heating, erasing means for heating the recording layer to an erasing temperature, and printing for printing on the erased recording layer using a thermal head Means, a conveying means for conveying the recording medium in the order of the erasing means and the printing means, and further comprising a heating member for heating the erasing means in contact with the surface of the recording medium, and a conveying means for bringing the recording medium into contact with the heating member. A printing / erasing apparatus comprising a transport mechanism, wherein the width of the heating element of the heating member is 1.2 to 5.0 mm in the recording medium transport direction. 17. A pre-heating means for uniformly heating a recording medium to a temperature of 40 ° C. or lower, which is lower than the erasing lower limit temperature specific to the recording medium, is provided between the erasing means and the printing means. 17. The printing / erasing device according to claim 16, wherein 18. The printing / erasing apparatus according to claim 16, wherein the erasing means doubles as a preheating means. 19. The printing / erasing method according to claim 16, wherein cooling means for cooling the recording medium heated in the erasing step is provided between the erasing means and the printing means. apparatus. 20. The printing / erasing apparatus according to claim 17, wherein a cooling means for cooling the recording medium heated in the erasing step is provided between the erasing means and the preliminary heating means. . 21. The printing / erasing apparatus according to claim 16, wherein cooling means is provided between the erasing means also serving as preheating means and the printing means. 22. The printing / erasing apparatus according to claim 16, wherein the temperature of the recording medium inserted into the apparatus is detected to control the temperature of the ceramic heater. 23. The printing / erasing according to claim 16, wherein the temperature of the recording medium inserted into the apparatus is detected to control the contact time between the ceramic heater and the recording medium. apparatus. 24. The printing / erasing apparatus according to claim 16, wherein the thermal head of the printing means also serves as the erasing means. 25. A cooling device comprising a cooling member for cooling at least a surface of the recording medium heated by the erasing device, the cooling member being a metal plate, a metal block or a metal roller. Claim 16
25. The printing and erasing device according to any one of to 24. 26. The printing / erasing apparatus according to claim 16, wherein the cooling member in the cooling means has a heat radiation structure. 27. The printing / erasing apparatus according to claim 16, further comprising an air cooling unit in addition to the erasing unit, the cooling unit, the printing unit, and the conveying unit. 28. A heating member constituting the erasing means, having a band-shaped heating resistor having a width of 1.2 to 5.0 mm on a ceramic substrate and covering the heating resistor with a glass protective layer thereon. The printing / erasing device according to any one of claims 16 to 27. 29. The printing / erasing apparatus according to claim 16, wherein an edge R (chamfer) of the heating member in a recording medium moving direction is 0.01 to 1 mm. 30. A heating member having a surface roughness Rz of 0.01 to
The printing / erasing apparatus according to any one of claims 16 to 29, wherein the thickness is 1 µm. 31. When the leading end of the printing portion of the recording medium reaches the ceramic heater position of the erasing means, the platen roll presses and contacts the recording medium, and the pressure is released when the rear end of the printing portion reaches the ceramic heater position of the erasing means. The printing / erasing device according to any one of claims 16 to 30, wherein: 32. The printing / erasing apparatus according to claim 16, wherein a transport speed of the recording medium by the platen in the erasing means is lower than a speed at which the recording medium enters the platen. 33. The printing / erasing apparatus according to claim 16, wherein the speed of carrying out the recording medium by the pair of carrying-out rollers in the erasing means is lower than the speed of carrying the recording medium by the platen.