JP2000135810A - Imaging apparatus, imaging method and imaging body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize area gradation with right circle dots by providing a thermal head having right polygonal or circular heating part and transferring an ink layer onto an intermediate transfer medium, stacking dots of different color formed of a set of different color dots by the ink layer at same position and then transferring a record image from the intermediate transfer medium onto a medium being transferred. SOLUTION: Under a state where an intermediate transfer medium 6 and a thermal transfer ribbon 7 are laid on a platen roller 10, the thermal transfer ribbon 7 is heated selectively by means of a thermal head 38 thus transferring an ink layer on the thermal transfer ribbon 7 selectively onto the intermediate transfer medium 6. The thermal head 38 is heat concentrating type and has a substantially right polygonal or circular shape. Size of a dot to be formed is varied by regulating thermal energy being generated from the heating section of the thermal head 38 according to an image data being applied thereto. In other words, gradation can be imparted because the dot size is varied according to image information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming technique for forming a multicolor image by thermal transfer using an area gradation by dots, and in particular, to obtain dots of different colors in order to obtain a predetermined color. The present invention relates to an image forming apparatus, an image forming method, and an image forming body using a method of stacking at a place.

[0002]

2. Description of the Related Art Conventionally, as a method of writing an image on an intermediate transfer medium based on image information, a thermal transfer method, an electrophotographic method, and an ink jet method described in the present invention are used in addition to a printing method which is most frequently used in practice. Method, thermal destruction method, and various transfer recording methods using a photopolymerized recording material can be cited as technically possible examples. Then, it is difficult to form an image directly on a final recording medium (final product) to which an image is to be applied using these image forming methods, the mass productivity is poor, or the cost becomes high. When any problem is involved, as described above, a method of forming an image on an intermediate transfer medium and then applying the image to a final product by transfer is adopted.

In the case where the image forming method is a thermal transfer method using a sublimable dye, for example, a thermal transfer ribbon having a sublimable dye coated on a base film so as to be capable of thermal transfer is used for final recording. A heat transfer ribbon is selectively heated based on image data prepared by using a thermal head or the like, and a desired image is transferred onto the transfer object. It is widely known as a known fact to record. According to this means, for example, in the case where the face of each person is individually recorded on an individual transfer object, the recording of a large number of images different from each other can be easily performed as a rich gradation color image on the transfer object. An advantage not obtained by the printing method is obtained in that recording is possible. If it is attempted to print such a record of the face of each person by a printing method, it is generally uneconomical since a great deal of cost, labor and time are generally required.

However, thermal transfer recording methods using sublimable dyes also have disadvantages. That is, the materials that can be dyed with the sublimable material are limited, and can be applied only to a transfer target made of a limited material such as, for example, polyester, acrylic resin, and vinyl chloride resin.

[0005] In order to perform thermal transfer recording using a sublimable dye in spite of using a material other than these as a material to be transferred, for example, Japanese Patent Application Laid-Open No. As disclosed in JP-A-81093, in an image writing section using a transfer ribbon of a sublimable dye and a thermal head, first, an image is written on a film-like intermediate transfer medium having an adhesive layer, and then transferred. There has been proposed a method in which an image on an intermediate transfer medium is heated and pressed together with the adhesive layer on a transfer object by using a transfer roller in the section to transfer the image to the transfer object.

The above-mentioned method is an example in which a sublimable dye is used. However, even when another color material is used, an image is formed on an intermediate transfer medium once, and a layer on which the image is formed is formed. The method of transferring the entire recording medium to the transfer target is basically the same, and this recording method is hereinafter collectively referred to as an indirect transfer method. The indirect transfer method means, in a narrow sense, a method in which an image is formed and a layer existing on an intermediate transfer medium is transferred to a transfer object, and in a broad sense, a method in which only an image is transferred to a transfer object. This means that the intermediate transfer medium including the portion where the image is formed is punched (or cut out) to transfer the entire intermediate transfer medium onto the transfer target. By the way, for example, the thickness of the transfer object as the final product (recording medium) is not constant, or there are irregularities (typical examples are non-contact IC cards), semi-finished products such as book paper etc. (Typical example is a passport), etc., when it is impossible (or difficult) to form an image directly on a transfer target, or when an image is directly formed on a transfer target. It is not an exaggeration to say that image formation cannot be practically performed unless the above-described indirect transfer method is used in the case where it is difficult to form the image in a large amount of time and time.

If an electrophotographic method is used as a method for writing an image on an intermediate transfer medium based on image information, in order to form an image in full color, the photosensitive member is charged or charged onto the charged photosensitive member. Latent image formation by exposure to light, development of a toner image corresponding to a latent image on a photoconductor, image transfer to a transfer member such as a transfer drum for temporarily storing a toner image of each color, unnecessary charging unit on the photoconductor It is necessary to repeat the electrophotographic process such as erasing, cleaning on the photosensitive member, etc. three times (three color colors) or four times (four color colors). Therefore, in this case, a problem due to the instability of image formation due to the use of a very unstable material such as static electricity, although it takes time, and measures to prevent such a problem are required, which is a problem. Further, since the size of the dots of the toner image forming the image cannot be changed much, it is basically a binarized image. Therefore, unless a method of pseudo area gradation using a dither matrix such as a Bayer type or Fatton type (including a screw type) is used, a large change in image density cannot be achieved, and the image quality of the image itself is coarse. is there.

On the other hand, in the case of using an ink jet method, since an image is formed on an intermediate transfer medium using a liquid ink, it is necessary to dry the intermediate transfer medium, which causes a problem of nozzle clogging. Furthermore, since the size of the dot cannot be changed much in the case of the ink jet method,
Since a method of pseudo area gradation such as a dither matrix or an error diffusion method is used, the resolution of an image tends to be reduced. In addition, about the thermal destruction method,
At present, it is impossible to perform full color expression.

For these reasons, image formation by a thermal transfer method using a sublimable dye is simple, low cost, and can realize high image quality and high resolution. It can be said that this is excellent as an image forming method.

However, the thermal transfer method using a sublimable dye has a major drawback. It is said that the sublimation dye itself is a very low resistance coloring material such as heat resistance, light resistance, and solvent resistance.
The durability of the image on the transfer receiving body as a final product is very poor. For this reason, for example, a heat-resistant temperature of about 1
In the case of an IC card having a temperature of 20 ° C., a decrease in image density due to a phenomenon such as thermal decomposition or re-sublimation of a sublimation dye occurs even at about 80 ° C.
It is impossible to clear 0 ° C.

Further, when paper such as a passport is used for the object to be transferred, the image may be blurred from the back side of the paper on which the image has been transferred due to a solvent atmosphere such as paradichlorobenzene or naphthalene which is often used as an insect repellent. When the temperature is high, various problems occur such that the image density tends to decrease due to the sublimation of the sublimable dye from the paper fibers.

Furthermore, since the sublimation type printing method itself is widely used in the world, when used for security purposes such as passports, there is a tendency that fraudulent operations such as forgery and tampering are easily performed. Another problem is that it is difficult to distinguish between authenticity and authenticity even if tampering is performed.

In order to solve the unique problem of the sublimable dye and to realize simple, low cost, high image quality and high resolution by the thermal transfer method, the amount of heat generated by the thermal head used for the thermal transfer is required. The density gradation is performed by changing the size of the dot to be transferred. That is,
Area gradation can be achieved by changing the area where the ink on the ink ribbon is softened or melted depending on the amount of heat controlled from the thermal head.

For example, as an ink ribbon, for example, a resin such as polymethyl methacrylate, polybutyral, or vinyl chloride-vinyl acetate-copolymer may be added to a coloring resin such as an organic dye, an organic pigment, or an inorganic pigment. Add the ingredients as needed. If necessary, an ink containing a wax component or a filler is used. For example, polyethylene terephthalate (abbreviated as PET) or polyethylene naphthalate (abbreviated as PEN) or the like is used for the base film of the ink ribbon, and ink of a required color is printed thereon using a printing method or the like. Apply.

In this method, a dye or pigment other than a sublimable dye can be used as a coloring material, so that the durability such as heat resistance, solvent resistance, light resistance, etc. can be greatly improved. It can be said that it is a system that has very high requirement conformity in fields that require high durability as well as security, such as stickers such as visas, stickers such as visas to be attached to passports, cards such as credit cards, driver's licenses etc. .

Also, the area gradation type fusion transfer method is very sensitive to the unevenness of the recording medium to be transferred, and if there is even a small amount of unevenness, the image cannot be directly transferred and formed. In other words, it can be said that it is almost impossible to obtain a high-quality image by the area gradation type fusion transfer method other than the indirect transfer method.

By the way, the above area gradation is converted into a color image,
That is, when forming with multicolor inks, the method of arranging the dots of each color (dot mapping) can be roughly divided into two types.

One is a screen method widely used in offset printing and the like, and the other is a method of arranging dots of each color at the same place, that is, a dot-on-dot method.

First, the screen method will be described. 2
When mapping dot images (stipples) of colors or more, each dot created by the thermal head has a substantially regular dot array. For example, if the main scanning direction is 300d
A thermal head of pi (dpi is a unit indicating the number of dots per inch) is used, and the
When mapping is performed by pi, a cluster of grids is formed at intervals of about 85 μm. In this specification, the main operation direction refers to a longitudinal direction in which the heat generating portions of the thermal head are arranged, and the sub-scanning direction refers to a direction orthogonal to the main scanning direction. When these regular clusters of dots are transferred and recorded on a recording medium (corresponding to image formation on an intermediate transfer medium in the present patent), a positional deviation (in the sub-scanning direction) is generally inevitable regardless of the degree. In many cases, this is due to speed fluctuations in the sub-scanning direction, slippage of the recording medium, or the like), which causes a slight shift in mapping of each color. And even if dots can be formed regularly with a single color, if there is a subtle misalignment when multiple colors are superimposed, the misalignment component will cause mapping and a beat phenomenon of each color,
There is a problem that undesired interference fringes (a typical example is moiré fringes) appear on the recorded image.

For this reason, the mapping position is shifted in advance for each color, for example, by changing the angle of the grid-like mapping (changing the screen angle) or changing the resolution of each color (for example, one dot for every two dots). In any case, the appearance of moiré fringes is suppressed by a method of intentionally performing dot mapping so that dot passes of each color do not overlap regularly, that is, a screen method.

However, when the screen method is used, the apparent resolution (gradation resolution) decreases (for example, 3
(These are equivalent to about 75 to 150 dpi with a thermal head of 00 dpi). Further, since the respective colors are arranged seemingly at random, a rough impression may be given.
Further, it is necessary to change each color image to each screen image, which places a heavy burden on a control CPU in the printer or a CPU such as a host computer which sends image data to the printer, and finally, the issuance time is greatly reduced. There is also the problem of getting lost. Also, passports, cards,
When an image is formed by this mapping means for security use in other areas, the image looks similar to that of offset printing or gravure printing, so it is difficult to use the features of the printing method as an effect to prevent unauthorized use such as falsification and forgery There is also.

On the other hand, the dot-on-dot method is a method of mapping dots of each color at almost the same position with high precision, and as long as there is no positional shift in each color, moiré fringes, color shifts due to color shifts, etc. Does not occur. In addition, since the image can be formed at the maximum resolution of the thermal head, the image mapping is basically not changed, so that the CPU is not burdened.
As a result, there are various merits such as an increase in issuance speed. However, a technique for accurately overlapping each color has not been established, and at present, this method has hardly been realized.

[0023]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has a function of holding a platen roller or the like for holding an intermediate transfer medium when performing transfer recording on the intermediate transfer medium. It is an object of the present invention to provide an image forming apparatus and an image forming method capable of realizing area gradation by using dots of almost perfect circle by dot-on-dot by devising a driving system of members and devising a thermal head as a writing device. This is the first purpose. Further, the present invention further provides an effect that can be formed by the image forming apparatus and the image forming method, and has a high effect of suppressing fraud such as forgery and tampering, or an effect of facilitating finding traces of such fraud. A second object is to provide a high image forming body.

[0024]

In order to achieve the above object, the present invention is directed to a photosensitive composition having a plurality of ink layers of different colors including a coloring material selected from the group consisting of pigments and dyes. An image forming apparatus using a thermal transfer ribbon and a long film-like intermediate transfer medium capable of transferring the ink layer from the thermal transfer ribbon, wherein (a) the intermediate transfer of the ink layer from the thermal transfer ribbon When transferring onto a transfer medium, a platen holding the intermediate transfer medium,
(B) a drive mechanism for driving the platen, comprising: a drive source; and a transmission member interposed between the drive source and meshing with each other and having a reduction ratio of an integral multiple. A heat generating portion having a polygonal or substantially circular shape, and selectively heating the thermal transfer ribbon in a state where the intermediate transfer medium and the thermal transfer ribbon are superimposed on the platen, thereby forming the ink layer. And (d) driving the thermal head in cooperation with the driving of the platen by the driving mechanism on the basis of image information, thereby forming a gradation image on the intermediate transfer medium. Control means for forming a recorded image on the intermediate transfer medium, wherein the gradation image is formed of a group of dots of different colors by the ink layer, and the dots of different colors are stacked at substantially the same location. And (e) superimposing the intermediate transfer medium, on which the recorded image is formed, and the object to be transferred, and applying heat and pressure thereto, thereby obtaining the recorded image. An image forming apparatus comprising: a heating and pressurizing unit for transferring the image from the intermediate transfer medium onto the transfer-receiving member; and all of the above (a) to (e).

It is to be noted that the shape of the heat generating portion in the present invention is a "substantially regular polygon" or "substantially circular" shape, of course, a true regular polygon (including a true square) or a true regular polygon. It also means a circle. However, these “substantially regular polygons” and “substantially circular” shapes are not necessarily limited to true regular polygons or perfect circles, and the whole view of the heating portion for one dot can be viewed macroscopically. , A regular polygon or a circle may be used. That is,
The corners of the polygon may be chamfered or rounded with a small radius, and the contour may be arranged even if part or all of the contour is not formed by straight lines or curves. To give a simple example, (1) an octagon having eight corners (not a regular octagon), but in the case where the four corners of a square have the same shape as a small chamfer, (2) ) A pentagon (not a regular pentagon), all four interior angles being 90
Degrees, but only one of the remaining interior angles is noticeably large (around 180 degrees) and nearly square, or
(3) It has a polygonal shape (or regular polygon) because it has a shape in which four corners of a square are rounded and there are no corners.
If this is not the case, it will eventually correspond to the shape of "substantially regular polygon" in the present invention. Strictly speaking, “substantially circular” may be an elliptical shape or a slightly distorted circular shape.

The number of corners of the regular polygon is irrelevant, and any number of corners may be used as long as it can be actually designed and manufactured. As the number of corners increases, the shape ultimately gradually approaches a perfect circle. Further, as for the number of corners of a regular polygon, while the number of corners is small, an even number is easier to obtain a good result in accordance with the object of the present invention than an odd number. But even for even numbers, there is no big difference. Also, as a balance of the dimensional ratio of the shape of the heat generating portion macroscopically, irrespective of the shape of “substantially regular polygon” or “substantially circular”, the width of the portion where the width of the shape can be the largest, and its width It is preferable that the ratio to the width in the direction orthogonal to the width direction is closer to 10:10. However, even if there is a slight difference in the ratio, there is a range in which a sufficiently favorable result can be obtained in practice, and this is not necessarily a limitable value, but as an approximate guide, 10: 7 to 10: It is in the range of about 10.

In reality, considering the ease of design and manufacture, the availability, the required cost, or the degree of influence for obtaining good results in accordance with the purpose of the present invention,
Squares, rectangles close to squares, or shapes close to these are generally preferred. Normally, one heat-generating portion forms one dot on the transferred object, but if the heat-generating portion for forming one dot on the transferred object is composed of a plurality of small heat-generating portions. 1 if configured
It is only necessary that the entire view of the plurality of small heat generating portions forming the dots is a “substantially regular polygon” or “substantially circular” shape when viewed macroscopically.

According to this, a thermal transfer recording medium having an ink layer using at least one of a pigment and a dye as a coloring material provided on a support is used, and the thickness of the ink layer is 1 μm or less. Therefore, the ink layer has good foil cut-off, and it is possible to easily perform area gradation, and since the shape of the heat generating portion of the thermal head is substantially square or substantially circular,
The formed dots are also substantially circular dots, and the area gradation can be easily performed. Further, since the heat generating portion of the thermal head for writing an image based on the image information has a substantially square or circular shape, a substantially circular dot can be realized.

When a fused transfer image is formed on the intermediate transfer medium by the above-described thermal head, a synchronous type drive transmitting means such as a timing belt or a gear, which does not generate a slip, is used as the drive transmitting means for the support. Since the drive reduction ratios are designed to be integral multiples of each other, since the ripple periods of the power transmission torque ripples of the respective reduction gears match,
It is easy to form an image by superimposing dot images of each color neatly. As a particularly preferable example of the heat-sensitive transfer recording medium, the invention disclosed in Japanese Patent Application Laid-Open No. HEI 7-117359 can be mentioned as a typical example. Notation). By using such a heat-sensitive transfer recording medium, it is possible to form an image with good area gradation by a heat-adhesive thin-film peeling method (indicated in the publication).

Of the thermal transfer ribbons (also referred to as ink ribbons), a traditional so-called hot-melt type is often called a wax type. In general, the ink of the wax-type ink ribbon includes materials other than the coloring material of the ink layer,
Materials having a very low melting point, such as waxes, are used very richly in proportion (weight proportion). On the other hand, materials other than the coloring material of the ink layer use a rich ratio of resins, and even if a material having a very low melting point, such as wax, is used, its use ratio (weight Some ink ribbons are very poor. The behavior of the ink at the time of thermal transfer is different between the wax type and the resin type. Therefore, the wax type is distinguished from the wax type by being referred to as a resin type (because the resin is rich). The thermal adhesive thin film peeling method and the like disclosed in the above publication also belong to the resin type.

However, the present invention can be applied to either a wax type or a resin type. However, in order to obtain a high-gradation, high-quality image, the thickness of the ink layer must be 1 in both cases.
It is generally good to use an ink ribbon having an extremely thin ink layer of about μm or less. If a high level of image durability is also required, a resin type is more preferable than a wax type. Both the wax type and the resin type are common in that the material other than the color material (mostly the binder material) in the ink layer is transferred to the image receiving layer side together with the color material. As described above, it goes without saying that the binder material is greatly different from the method in which only the sublimation dye, which is the remaining color material, migrates to the image receiving layer side on the base film side.

By the way, in the case of the first aspect of the present invention, especially when the platen is formed in a roller shape, the conveyance and transfer of the intermediate transfer medium are performed.
It is preferable that holding and image formation by thermal transfer are further facilitated. According to the first aspect of the present invention, particularly, in the vicinity of the heat-generating portion of the thermal head used for performing thermal transfer, there is no concave portion (dent, etc.) at a position in contact with the thermal recording medium (base surface of the ink ribbon). By doing so, it is easy to smoothly transfer good heat from the heat generating portion of the thermal head, and it is easy to contribute to the realization of dot-on-dot in which each color is overlapped with a good area gradation from small dots to large dots.

According to a second aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein the intermediate transfer medium has at least an image receiving layer on a substrate film, and Is formed on the image receiving layer and is transferred onto the transfer receiving body together with at least the image receiving layer. According to this, a layer containing a thermal transfer recording image is transferred from the intermediate transfer medium by transfer. It can be provided on the body, and the layer containing the thermal transfer recorded image also serves as a protective layer of the image, which is preferable. In addition, the heat at the time of providing the layer containing the thermal transfer recording image on the object to be transferred can also be used to form a good image with a relatively small amount of heat and temperature. This is advantageous in reducing the size of the image forming apparatus, simplifying the mechanism, and reducing the cost.

According to a third aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein the intermediate transfer medium heated and pressurized by the heating and pressurizing unit and the object to be transferred are formed. On the other hand, the image forming apparatus further comprises a punching means for punching out the intermediate transfer medium along the contour of the object to be transferred, so that the recorded image is transferred onto the object to be transferred together with the punched portion of the intermediate transfer medium. It is characterized by the following. According to this, the layer containing the thermal transfer recorded image on the intermediate transfer medium is adhered onto the transfer object, and simultaneously and / or thereafter, the intermediate transfer medium is punched along the contour of the transfer object, whereby the intermediate transfer medium is punched out. A portion of the area on the intermediate transfer medium, including the base film of the transfer medium, is provided with the thermal transfer recording image on the transferred body, so that the thermal transfer recorded image on the transferred body is Thick layers can be provided at once. That is, in consideration of providing a protective layer for protecting a thermal transfer recorded image, for example, a protective layer having high performance for protecting the image can be easily provided, which is preferable. For example, an appropriate design may be adopted, such as placing the transferred object on a die having a shape conforming to the contour of the transferred object, and punching out from above with a cutter matching the die.

According to a fourth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to third aspects, and in particular, the recording image formed on the intermediate transfer medium further includes a binary image. It is characterized by including. As a gradation image,
A representative example is to provide an image of a person's face as one of the visual information on a legitimate owner of a medium requiring security such as a passport or a card. Also,
As a binary image, as one of the visual information on the authorized owner, the person's first and last name, date of birth, affiliation, address,
Etc. are recorded. Binary images having a high image density contrast are also used for so-called OCR characters, symbols, etc. so that machine reading becomes easy.

According to a fifth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to third aspects, and in particular, the driving source is configured such that a reduction ratio of the transmission member to the transmission member is an integral multiple. It is a stepping motor driven by the number of steps. According to this, since the driving source of the intermediate transfer medium holding member is a stepping motor driven by an integral multiple of the number of steps of the speed reducer, for example, a stepping motor for moving one pitch of dots in the sub-scanning direction is used. Synchronous step feed such as 4 steps or 5 steps in the number of motor steps
The alignment accuracy of each color is further improved.

In the image forming apparatus according to the fifth aspect, it is preferable to use a damper in combination with the stepping motor. According to this, a damper for suppressing unnecessary vibration is used in the above-described stepping motor, so that the alignment accuracy of each color is further improved, and the step between each step is stopped during printing to perform the fusion transfer (this is referred to as “stopping”). This is particularly important because it depends on how to reduce unnecessary vibration between rotation and stop of the stepping motor or the like in a short time.

The image forming apparatus according to any one of claims 1 to 5, wherein the platen has a rigid layer made of a polymer compound on a surface side, and an elastic material made of a polymer compound is formed inside the rigid layer. It is preferred to have a layer. According to this, the intermediate transfer medium holding member is a roller, a rigid layer made of a polymer compound is formed on the surface side of the roller, and an elastic layer made of a polymer compound is provided inside the rigid layer. The heat-generating part of the thermal head does not sneak into the heat-sensitive transfer recording medium (ink ribbon) side, so good heat transfer can be realized and the rigid layer on the surface maintains the accuracy of the roller surface. High-precision color matching of each color can be performed.

On the other hand, when a holding member having no rigid layer on the surface, such as a so-called rubber simple substance, is used, the vicinity of the heat generating portion of the thermal head sinks into the heat-sensitive transfer recording medium side, and as a result, heat transfer is desired to be conducted. Not only can good dots not be formed because they are unexpectedly diverged, but also the intermediate transfer medium is held with high accuracy by unnecessary elastic changes of rubber or other elastic layers or temperature changes. As a result, it is difficult to accurately register each color.

According to a sixth aspect of the present invention, there is provided a thermal transfer ribbon having a plurality of ink layers of different colors including a color material selected from the group consisting of pigments and dyes, and the ink layer can be transferred from the thermal transfer ribbon. A long film-shaped intermediate transfer medium, the image transfer method comprising: (h) forming the intermediate transfer medium and the heat-sensitive transfer ribbon on a platen on the basis of image information. An image forming step of forming a recording image including a gradation image on the intermediate transfer medium by repeating an operation of selectively heating the thermal transfer ribbon by a thermal head for each color, wherein the gradation image is A color set by forming a group of dots of different colors by the ink layer and stacking the dots of different colors substantially at the same position, and a driving mechanism of the platen Using a drive source, and a transmission member interposed between the drive source and the platen, meshing with each other, and having a reduction ratio of an integral multiple, (i) the intermediate transfer on which the recorded image is formed. A heating and pressurizing step of transferring the recorded image from the intermediate transfer medium onto the transfer medium by superimposing the medium and the transfer medium and applying heat and pressure thereto; An image forming method characterized by including all of (i).

The invention according to claim 7 is based on the image forming method according to claim 6, and in particular, (nu) the intermediate transfer medium has at least an image receiving layer on a base film,
The recording image is formed on the image receiving layer and is transferred onto the transfer receiving body together with at least the image receiving layer.

The invention according to an eighth aspect is based on the image forming method according to the sixth aspect, and in particular, (l) the intermediate transfer medium and the transfer object heated and pressed by the heating and pressing means. And a punching step of punching the intermediate transfer medium along the contour of the transfer target to transfer the recorded image onto the transfer target together with the punched portion of the intermediate transfer medium. It is characterized by doing.

A ninth aspect of the present invention is based on the image forming method according to any one of the sixth to eighth aspects, and particularly includes a gradation image formed on the intermediate transfer medium in the image forming step. The recorded image further includes a binary image.

The tenth aspect of the present invention is the sixth to eighth aspects.
Based on the image forming method according to any of the above, in particular, the image forming step, as a binary image, a character, a number, a symbol, a mark, using a micro character using any one selected from the group consisting of a pattern A step of forming using a set of dots by the ink layer.

According to an eleventh aspect of the present invention, based on the image forming method of the ninth aspect, in the image forming step, when the recorded image is read by a scanner as the binary image, interference may occur. A step of forming a pattern for generating stripes by using a set of dots by the ink layer.

According to a twelfth aspect of the present invention, there is provided an image forming body, comprising: a base material, a recorded image, and a transparent resin disposed on the base material so as to cover the recorded image in a visible manner. Wherein the recorded image includes a gradation image and a binary image, and the gradation image is composed of a set of dots of different colors by the ink layer, and the dots of different colors are located at substantially the same location. By stacking, the binary image has a set color, and the binary image is formed by the group of dots, and is formed by using any one of a group that can be selected from a group consisting of letters, numbers, symbols, marks, and patterns. An image forming body comprising a character.

According to a thirteenth aspect of the present invention, based on the image forming body according to the twelfth aspect, in particular, the micro-character is individual information relating to a main portion of the recorded image.

According to a fourteenth aspect of the present invention, there is provided an image forming body, comprising: a base material, a recorded image, and a transparent resin disposed on the base material so as to cover the recorded image visually. Wherein the recorded image includes a gradation image and a binary image, and the gradation image is composed of a set of dots of different colors by the ink layer, and the dots of different colors are located at substantially the same location. By stacking, having a set color, the binary image has a pattern formed by the collection of dots, which generates interference fringes when the recorded image is read by a scanner, An image forming body characterized by the following.

A fifteenth aspect of the present invention is based on the image forming body according to the fourteenth aspect, and in particular, the pattern for generating the interference fringes includes a plurality of diagonal directions that differ depending on dots formed at a high resolution pitch. It is a pattern formed so that a thin line extends.

As described above, in the present invention, as one of the requirements for forming an image based on the area gradation, dots of different colors are basically formed at substantially the same place. The meaning of "location" is as follows:
It also includes very slight misregistration of stacked dots of different colors. That is, the “substantially the same portion” in the present invention means that the center-to-center distance of the color dot whose position is the most displaced among the stacked different color dots is approximately 1/1 / the dot formation pitch corresponding to the resolution. This includes the case where the deviation is very small within three. In the present invention, in order to obtain a high quality image with sharp image quality, it is preferable to form dots with extremely high positional accuracy so that the center-to-center distance is within 1/4 of the pitch. It is important that there is. In the present invention, if the size (diameter) of a dot is too small somewhere in the gradation image,
Even if there is a place where dots do not overlap between colors, apply the above-described method of examining the center-to-center distance, or make the dot size (diameter) sufficient from other places in the gradation image. Then, the method of examining the center-to-center distance described above is applied after selecting the place where the dots between the greatly different colors overlap.

[0051]

FIG. 1 is a schematic view showing an example of an image forming apparatus according to the present invention.
(1 ′) is set on the tray 2 (2 ′) via a silicone rubber base rubber sheet whose surface is coated with a fluorine-based polymer compound (not shown). In FIG. 1, the positions of the transfer target 1 and the tray 2 indicated by solid lines are positions when the image on the intermediate transfer medium 6 is heated and pressed on the transfer target 1 by the heat roller 40. The transfer of the non-transferred body is performed by the actuators (not shown) and the driving system so that the non-transferred body is moved by the wheels 4 (4 ′) and 5 (5 ′) along the rail 3. The transfer target 1 does not necessarily have to be designed to be transported on a tray depending on the situation. That is, when the transfer target is a booklet such as a passport or a passbook, or a sticker such as a visa, the flexibility is often considerably high because of the material used or the small thickness. On the other hand, when the transfer target is, for example, cards, the rigidity is often higher than that of the former, because the main material (generally, plastic is the main material) or the thickness is large. Considering these characteristics, cards require less use of trays than booklets and stickers in general. You can decide.

The intermediate transfer medium 6 is supplied to the supply reel 23
From the guide rollers 13, 15, 16, 39
And transport rollers 17 and 18 (if traveling, the rotation direction D
h), 20 and 19 (in the case of proceeding, the rotation direction Dd), the platen roller 10 which is transported to the take-up reel 24 and is coated with a fluoropolymer on a silicon-based elastomer layer when writing an image. The data is written while being held by the clamp rollers 8 and 9 above. Reference numeral 25 in the figure denotes a cleaning roller for removing dust on the platen roller.

In the example described here, the intermediate transfer medium 6 is
A long base film 61, a transparent resin protective layer 62 and a resin image receiving layer 6 laminated thereon as an example.
3 is provided. Here, the protective layer 62 also serves as a release layer that separates the base film from the base film, and the image receiving layer 63 is used when the intermediate transfer medium and the transferred body are heated and pressed after image formation. , Also serves as an adhesive layer exhibiting adhesiveness to the transfer-receiving body (that is, the image-receiving layer / adhesive layer 6).
3). Further, the intermediate transfer medium 6 has a security image layer using an image by a hologram or a diffraction grating in the layer structure. The intermediate transfer medium 6 is appropriately positioned on the platen roller by using the registration mark sensor 11 for positioning these images such as holograms. The cleaning roller 12 is used to remove dust and dirt on the surface of the intermediate transfer medium 6 on which the image is written.
In addition, a static elimination brush (not shown) is provided.

It is also preferable to appropriately provide a bending adjustment mechanism capable of adjusting the bending and tension (tension) of the intermediate transfer medium 6 in the middle of the conveyance path of the intermediate transfer medium 6. according to this,
In addition to simply adjusting the bending and tension (tension) of the intermediate transfer medium 6, the first stage of image formation (the image recording step on the intermediate transfer medium 6) and the second stage of image formation (the image of the intermediate transfer medium is This is also effective and preferable when the image forming step is independently performed in parallel with each other, or when the processing speed of the image recording operation for each color is repeatedly increased in the previous stage of image formation. .

In the embodiment of the present invention, image writing is performed by using an ink using an organic pigment or an inorganic pigment as a coloring material (a type in which a binder material or the like in an ink layer is transferred together with the coloring material) in this example. Performs thermal transfer. The thermal transfer ribbon 7 is selectively heated by the thermal head 38 in a state in which the intermediate transfer medium 6 and the thermal transfer ribbon 7 are overlaid on the platen roller 10, so that the ink layer on the thermal transfer ribbon 7 is selectively heated. The image is transferred onto the intermediate transfer medium 6.

According to the present invention, the thermal head 38 is a thermal concentration type thermal head, which is arranged in a line in the main scanning direction.
Each of them has a substantially regular polygon or a substantially circular shape. In one example, the outer surface of the heat generating portion has a plurality of heat generating portions 38a having a substantially planar shape. The outer surface of the heat generating portion of the thermal head 38 has few irregularities.
Some have a surface roughness of about 0 nm (center line average roughness). In this specification, the main scanning direction D1 refers to the longitudinal direction in which the heat generating portions of the thermal head 38 are arranged (the longitudinal direction of the line type thermal head), and coincides with the width direction of the intermediate transfer medium. The sub-scanning direction D2 is the main scanning direction D
The direction orthogonal to 1 is the same as the transport direction of the intermediate transfer medium.

In this example, the heat generating portion of the thermal head 38 has a rectangular shape which is almost a square, such as [main scanning direction D1] 70 μm × [sub-scanning direction D2] 80 μm. According to the image data applied to the heat generating portion of the thermal head 38, the heat energy generated from the heat generating portion is adjusted, and the size of the formed dot is arbitrarily changed. That is, the tone is given to the image by changing the size of the dot according to the image information. Note that the tone expression itself can be performed by using a mixture of a plurality of colors and using a mixture of colors, or by using a single color, or any other method.

A voltage corresponding to the image information is applied to the heat generating portion of the thermal head 38 via the cable 36. In addition, a peel plate 35 is provided to satisfactorily peel off the thermal transfer ribbon 7 transferred by the thermal head 38 from the intermediate transfer medium 6.

In this example, the thermal transfer ribbon 7 has a long base film 71 and a plurality of ink layers 72 of different colors disposed thereon, and each of the ink layers 72
A color material selected from the group consisting of pigments or dyes (here, a pigment is selected and a resin-type ink layer is employed).
The ink layers 72 of the thermal transfer ribbon 7 are, for example, three color layers 72C, 72M, and 7 of C (cyan), M (magenta), and Y (yellow) for forming an area gradation image.
Y and Bk (black) layer 7 for forming a binary image
2B. The ink layers 72C, 72M, 7Y of a plurality of different colors of the thermal transfer ribbon 7 and the Bk layer 72B for forming a binary image are areas (surfaces) independent of a predetermined length along the ribbon supply direction. So that the base film 7
1 are arranged in a plane-sequential manner.

The thermal transfer ribbon 7 includes these C,
In addition to the ink layers of a total of four colors of M, Y and Bk, some coloring ink or any ink layer not related to the color is appropriately disposed on the same base film as the four color ink layers. You can do it. The above-mentioned four ink layers are, for example, so-called special colors such as gold or silver, or ink layers for security use which include a fluorescent material, a phosphorescent material, an infrared absorbing material, and the like. If the thermal transfer ribbon 7 is also provided with these ink layers other than the above four colors, these additional layers are, by design, three layers of CMY (or four colors of CMYBk) in the longitudinal direction of the ribbon. They may be arranged either before or after or between them. In the image formation according to the present invention, when it is desired to easily and surely obtain high-gradation images with good image quality, the thickness of the ink layer equivalent to the thickness of each dot is also extremely thin, 1 μm or less. It is preferable to use a thermal transfer ribbon 7.

The ink ribbon 7 is supplied from the supply reel 26, and is conveyed to the take-up reel 27 by the guide roller 36 and the conveyance roller 28 (in the rotating direction Dg when proceeding), 29, and the cleaning rollers 32 and 33 which also serve as the guide roller. Then, an image is formed on the intermediate transfer medium 6 based on the image information by the heat concentration type thermal head 34.

The ink ribbon 7 is distinguished and aligned by reading sensor marks formed on the ink ribbon in advance by the sensors 30 and 31 to distinguish each color.

The order in which a plurality of colors are thermally transferred depends on the characteristics (transparency, hue, transfer density, etc.) of the ink layer used, the purpose of image quality design, the characteristics of the apparatus, and the like. In consideration of the above, the order of colors to be thermally transferred may be appropriately designed.

As a typical example, on an intermediate transfer medium,
First, after recording a binary image in Bk (black),
An image forming method for forming a multicolor gradation image by area gradation with three colors in the order of CMY is also preferable. In this case, when the formed image is transferred onto the transfer target by heating and pressing using a heat roller in a subsequent step, the alignment between the intermediate transfer medium and the transfer target is determined by the optical sensors 100 and 101 (FIG. 1). It is convenient to form an alignment mark to be executed by using the ink of the first Bk, since Bk is easier to detect than in the case of other colors.

In one screen, the area where the gradation image is formed and the area where the binary image is formed are separated from each other along the longitudinal direction of the intermediate transfer medium. If the lengths are different, the start and end positions of the thermal transfer for each color do not necessarily have to match.
For example, the three colors of CMY may be the same, and only one color of Bk may be designed differently from the others, depending on the purpose and various circumstances.

The size of the dot of each color is determined based on the halftone of the image to be expressed at that location, and the ink dot is formed by thermal transfer corresponding thereto.

The intermediate transfer medium, on which an image has been formed on the intermediate transfer medium, is heated and pressurized on the transfer target 1 by lowering the heat roller 40 in the direction Db. Heat bonding layer), hologram layer,
A so-called image layer such as a protective layer (not shown) is transferred by heating and pressing. However, safety shutters 41 and 42 are provided between the heat roller 40 and the object 1 to be transferred, and the shutters 41 and 42 move in the directions Dc and Dc ′ only when the heat roller 40 descends in the direction Db. The shutters 41 and 42 are normally closed so that human hands or the like do not touch the heat roller 40 and do not get burned.

The heat roller 40 is a hollow cylinder having a halogen lamp heater 37 inside and a blackened inside of a section to absorb the heat radiation from the halon lamp heater. An inverted crown-shaped heat roller provided with a conductive fluorine-based polymer compound on the outermost surface. Then, by rotating the peripheral speed (rotation direction is Di) slightly faster than the transport speed of the intermediate transfer medium or the medium to be transferred, tension is intentionally generated outside the center of the intermediate transfer medium being heated, and the intermediate transfer medium is rotated. The generation of a transfer medium is prevented. The heat roller 40 detects the surface temperature with the temperature sensor 21 and keeps the surface temperature constant by a temperature controller or the like (not shown). Further, in order to keep the heat roller surface clean at all times, a cleaning roller is used. 22 are provided.

Then, other detailed conditions in this embodiment are presented as follows. Intermediate transfer medium properties: Multi-layer coated on 25 μm PET base. A mixed resin mainly composed of urethane resin, epoxy resin, etc. for the image receiving layer and thermal adhesive layer on the outermost surface. Ink ribbon characteristics: Uses organic pigment-based coloring material. In particular, Bk uses an inorganic pigment. The thickness of the ink layer is 0.
2 to 0.6 μm Base rubber sheet: Silicon rubber (rubber hardness JI
S (A): 50 °) The surface is coated with a tetrafluoroethylene polymer or a hexafluoropolypropylene polymer. Transfer object: paper base material with a thickness of 200 to 800 μm

Heat roller: Heat source; Halogen lamp heater Temperature control; Temperature control by detecting roller surface temperature Core metal; Hypertonic aluminum Inner blackening treatment Elastomer layer; Heat-cured silicone rubber Thickness 0.5mm Roller surface material; Copolymer of ethylene tetrafluoride and perfluoroalkylvinyl ether provided with a surface Roller surface shape; inverted crown type Circumferential speed is slightly higher than medium transport speed Roller surface temperature; 180 ° C Heating / pressing speed: 15 mm / sec Heating Pressing line load: 3.0 kgf / cm Thermal head: Heating part characteristics: Heat concentrated type Heating part density: 300 dots / inch Heating part shape: Almost square (70 μm × 80 μm)

When the image formed on the intermediate transfer medium 6 is transferred onto the transfer object 1, the area on the transfer object may be on the entire surface of the transfer object, or may be on the entire surface. It may be designed as appropriate, such as only a portion excluding a peripheral edge, or only a portion on a surface mainly including an image portion. In addition, in the case of frequently seen on cards, there is a local area that is difficult to cover over, such as a sign panel portion on a surface of the card as a transfer object or a terminal portion of an IC card. In some cases. In that case, it may be appropriately designed so as to provide a local non-image forming area on the transfer object.

As a specific measure, in order to transfer an image to a necessary area in accordance with an image forming area or a non-image forming area on the surface of a transfer target, basically, an image is formed in an image forming area. May be heated and pressurized on the surface of the transfer object, and the image may not be heated and pressurized on the surface of the transfer object in the non-image forming area. As an example, in the case of heating and pressing using a heat roller, the size (width and diameter) of the heat roller is appropriately designed, or the surface of the heat roller is appropriately designed to have irregularities. do it.

In this specification, the image receiving layer of the intermediate transfer medium has been described as a typical example in which the image receiving layer itself is both an image receiving layer and an adhesive layer having an adhesive property to a transferred body. In some cases, the combination of the image receiving layer and the material of the image receiving layer may not always exhibit adhesiveness due to poor compatibility between the material of the surface to be transferred of the object and the material of the image receiving layer. Therefore, in such a case, for example, (a)
An adhesive layer is provided on the image receiving layer on which the image is formed, or on the transfer surface of the transfer object (for example, by transferring the adhesive layer onto the surface, or by applying an adhesive, or the like). Or (b) an image receiving layer on which an image is formed;
A countermeasure may be appropriately taken such as superimposing the intermediate transfer medium and the transfer receiving member with the adhesive sheet interposed between the transfer receiving surface of the transfer receiving member and heating and pressing.

Next, the drive transmission system will be described briefly. For example, in this embodiment, a platen roller is used as an intermediate transfer medium holding member, and a stepping motor is used as a driving source. However, each motor including the stepping motor uses some kind of reduction mechanism for two reasons. Things are normal. The speed reduction mechanism can be classified into an "asynchronous type" speed reduction mechanism using a V-belt or a flat belt, and a "synchronous type" speed reduction mechanism using a timing belt, a spur gear, a helical gear, or the like.
The two reasons are as follows: (a) In order to obtain a sufficient torque for rotationally driving the platen roller and the like, (b)
To reduce the speed to an appropriate drive speed.

However, the asynchronous speed reduction mechanism is not suitable for strict alignment because some kind of slip phenomenon such as belt slip occurs. On the other hand, in the case of a synchronous reduction mechanism such as a timing belt or a gear (an involute gear, a cycloid gear, etc.), basically, no slip phenomenon occurs because the teeth are engaged with each other. However, in the case of this synchronous type speed reduction mechanism, each tooth has an error such as a tooth profile error or a meshing error regardless of whether the gear or the timing belt is used, and these errors generate a “position shift”. Get out.

FIG. 2 shows an example of a timing belt deceleration timing in which the speed is reduced and the torque on the power side is increased by reducing the speed from N1 to N2.
In this example, the reduction ratio from N1 to N2 is an integral multiple such as 4: 1 in the ratio of the number of teeth. In the case of a timing belt, there is some variation depending on each manufacturer, but an error at the time of engagement between the pulley and the belt occurs periodically. The position shift (first-order integral component of the speed change) caused by these errors also has a periodic change synchronized with each tooth, such as V1 for N1, and V2 for N2.

When the speed reduction ratio between the timing belt and the pulley, that is, between the transmission members is set to be an integral multiple,
Since the meshing period of the teeth, that is, the cogging cycle of the positional shift is always synchronized, the cycle of the positional shift caused by the error of the meshing of the transmission members is also synchronized.

However, if the reduction ratio between the transmission members is not an integral multiple (for example, if the ratio of the number of teeth is 4: 1.33, etc.), the positional deviation cannot be synchronized, and the positional deviation itself is not obtained. Are accumulated, and it is very difficult to drive the transport system to the same position constantly. Alternatively, a step required for the countermeasure and a mechanism for the step are required, which is not preferable. The above is the description of the timing belt, but the same applies to the gear.

For example, in the case of an involute gear, if the tooth profile is an ideal shape, basically no speed fluctuation occurs, so that a position shift which is a first-order integral component should not occur. In particular, a periodic positional deviation always occurs due to the inability to ideally form the tooth profile, and the elastic deformation of the tooth profile and the tooth stripe deformation due to friction and wear during use. These are also applicable to cycloid gears and other synchronous type reduction gears in general.

Here, the platen roller drive system will be described by way of an example. FIG. 3 shows a stepping motor 50.
In this example, the drive is transmitted to the pulley 58 directly connected to the platen roller. First, the stepping motor 50 transmits the drive to the pulley 51 and the pulley 52 via the belt 53 at a reduced speed. Then, power is transmitted from a pulley 59 via a belt 54 to a pulley 55 of an electromagnetic clutch 60 that turns on and off the transmission of drive via a belt 54, and power is further transmitted from a pulley 56 to a pulley 58 directly connected to a platen roller via a belt 57.

Next, FIGS. 4 and 5 show examples of these transmissions. FIG. 4 shows the reduction ratios of the gears between the gear pulleys 51 and 52, between the gear pulleys 59 and 55, and between the gear pulleys 56 and 58 by the ratio of the number of teeth to 4: 1, 2: 1, respectively.
An example in which an integer multiple such as 7: 1 is set is shown. In the experiment, the deceleration pattern of FIG. 4 was applied to a stepping motor equipped with a damper 50d for suppressing unnecessary vibration. C,
When the platen roller 10 scans the M and Y colors in the sub-scanning direction at a pitch of 300 dpi with 8 pulses,
It was confirmed that good positional accuracy in which the dot position deviation of each color was within ± 5 μm could be realized.

In FIG. 5, the reduction ratio between the respective gear pulleys as in FIG.
They are set in integral multiples, such as 1, 2: 1, 7: 1. The platen roller 10 is set to 300 dp in the sub-scanning direction with 6 pulses
Except that scanning was performed at the i-pitch, the same procedure as in FIG. 4 was performed, and it was confirmed that high-accuracy positioning could be performed.

In general, an image-formed body prepared by using the present invention includes a multicolor image formed by area gradation on a substrate as a transfer-receiving member 1 and a black-and-white image formed by a binary image. Having. The reason is that these are generally required for an image forming body that requires security. According to the present invention, if necessary, an image forming body having no binary image can be created.

The dots of each color forming an image are 1
It has a thickness of less than μm. The substrate and the image are covered with a transparent resin layer derived from a layer that also serves as a protective layer of the intermediate transfer medium 6. The multicolor image portion based on the area gradation is, for example, a face image of the owner's personal, and the black and white portion is
For example, it is a character or symbol part including individual information relating to the owner. Representative examples of the individual information are the first and last name, date of birth, and affiliation of the genuine owner.

In consideration of the case where the image forming body is a certificate other than a passport, the individual information further encodes (or encrypts) information on a living body such as various code numbers, fingerprints, fine prints and retinas. ) Or any of these pieces of information and perform some conversion to barcode,
It may include two-dimensional barcodes and other patterns.

Incidentally, it is preferable that the characters and symbols for OCR to be machine-read are formed of a binary image using Bk ink in order to obtain a high-contrast image so as to be suitable for machine reading. A typical example is the OCR defined by ICAO, an international standard for passports.
It is also preferable to use the Bk ink for forming a binary image such as characters and symbols for printing.

According to the present invention, letters, numbers, symbols, and the like representing (or related to) general information and the above-mentioned individual information.
Micromarks with very small and sharp image quality can be suitably formed by using the marks and patterns as part of the recorded image.

FIG. 6 shows an example in which a micro character 85 is formed as a binary image by using a thermal head 38 and a set of dots 84 transferred using a Bk ink layer 72B. In other words, it is desirable to secretly form micro-characters in the recorded image, which are so small that they are difficult to find by mere visual observation. If the image forming body is a forged one, and if such micro-characters are not formed, it can be easily determined that the image is a forged one. Also, even if forgery is technically feasible, including micro-characters, the use of micro-characters reduces fraud such as counterfeiting because the labor, days, and cost required for counterfeiting increase. It is effective in preventing.

Note that the location, contents,
The number and the like can be appropriately changed depending on the design. In particular, when individual information is adopted as the content of the micro-character, the effect of preventing and suppressing forgery is enhanced. For reference, each dot pitch in the example in FIG. 6 is set to 300 dpi in both the main scanning direction D1 and the sub-scanning direction D2.
Also, by changing the dot diameter of the curved portion of the character, the character can be smoothed.

FIG. 7 is also an example of micro-characters,
Each dot pitch is 300 dpi in the main scanning direction D1,
Except that the sub-scanning direction D2 is set to 1200 dpi, it is the same as in FIG. In addition, changing the interval at which the heat-generating portions of the thermal head are lined arbitrarily usually requires that the thermal head itself be replaced with one having a different specification. That is, it is not realistic to appropriately change the dot interval in the main scanning direction D1. On the other hand, in the sub-scanning direction D2, the dot formation pitch can be changed by appropriately changing the conveyance pitch of the intermediate transfer medium 6.
Therefore, it is preferable to change the dot interval in the sub-scanning direction D2 to form dots densely and to enhance the smoothing performance of characters, in order to make micro-characters finer and improve resolution.

According to the present invention, when a recorded image is read by a scanner, a pattern that causes interference fringes in the output image can be formed as a part of the recorded image.

FIG. 8 shows an example in which a pattern 87 for generating interference fringes is formed as a binary image by using a thermal head 38 and a set of dots 84 obtained by rotating the Bk ink layer 73B.

The pitch of the dots 84 in the example shown in FIG. 8 is set to 300 dpi in the main scanning direction D1 and 1200 dpi in the sub-scanning direction D2. A pattern in which fine lines extend in a plurality of different oblique directions is formed by utilizing the high positional accuracy at which dots are formed. As a result, no matter how the reading position (or reading direction) of the scanner is changed due to the relationship between this pattern and the reading pitch of the scanner, interference fringes always occur in the image output by performing the scanner reading. I will be.

In the recorded image (genuine product) formed according to the present invention, an interference fringe generating pattern 87 exists, but since there is no interference fringe, such a pattern 87 exists. I don't usually notice that I'm there.
However, in the case of copying using a scanner, for example, using a copying apparatus based on xerography, interference fringes occur in a portion corresponding to the pattern 87 on a genuine product.

By utilizing this fact, it is desirable to secretly form an interference fringe generation pattern that is difficult to find in a part of the recorded image. If such interference fringes occur on the image forming body, it is noticed that the image forming body has been forged through scanner reading. This is also effective in deterring and preventing fraud such as forgery. It should be noted that it is also possible to design in advance such that when the interference fringes appear, the pattern looks like a character such as "VOID", and to form the interference fringe generating pattern in such a manner. This is preferable because it is easier to find traces of fraud.

The resolution of the image according to the present invention is not limited to the examples shown in FIGS. 6 to 8, but can be determined variously depending on the design of the apparatus and the processing software. That is, the resolution is determined for each of the main scanning direction D1 and the sub-scanning direction D2.
It can be higher than in the examples of FIGS. 6 to 8 (by design). For example, the resolution is 300 to 24
About 00 dpi or more is possible by design. Changing the resolution in the main scanning direction (as described above)
Since the thermal head itself needs to be replaced, the degree of freedom of relative change is not as high as in the sub-scanning direction.

In the above-described example, only the passport was mainly described as the image forming body, but the present invention is applicable to various image forming bodies (transferred bodies). That is, today, many image forming bodies are required to have security from a market or social point of view. For example, it is desired that forgery is difficult or that forgery can be easily detected even if forged. ing. Examples of such an image forming body include a booklet represented by a passport or a bankbook, and a type of visa attached to a passport (visa).
Stutkers represented by, and credit cards,
Cash card, bank card, debit card, prepaid card, point card, various licenses, ID card, employee card, members card, student card, magnetic card, IC card (contact type, non-contact type, contact and non-contact type Card, such as a composite type, a composite type using contact and light, a composite type using contact and infrared light, and an optical card.

Note that the present invention can be applied to any image forming body other than the above-mentioned image forming body as long as security is required. Further, the present invention is not necessarily limited to the image forming body requiring security and the related image forming field, and can be applied to other fields as long as it is used for image forming. . However, when the present invention is applied to a field where security is required, the value of the present invention can be evaluated higher than when it is not.

[0099]

According to the present invention, the dots to be formed are also substantially circular dots, and the change of the dots due to the area gradation is a change in the dot diameter of a substantially perfect circle. Is very smooth, and it is easy to distinguish it from a conventional sublimation type image. For example, when the image is used in an ID printer such as a passport, it is easy to determine authenticity. That is,
Area gradation can be easily performed while performing thermal transfer. In addition, when a very thin ink layer having a thickness of 1 μm or less is used as the thermal transfer ribbon to be further used, the cutout of the foil is very good, and the area gradation by the thermal transfer becomes very easy.

Further, according to the present invention, since an image can be formed without applying a screen, there is basically no need to convert the image, and the load on the CPU is greatly reduced. Furthermore, since each dot is formed in a substantially round shape at the same position, it can be easily distinguished from a conventional sublimation type image. For example, when used for an ID printer such as a passport, it is very difficult to determine authenticity. Help.
This is because, in the method of driving the platen holding the intermediate transfer medium, for example, in the case of a drive transmission method using a synchronous type speed reducer such as a timing belt or a gear, the drive slip does not occur (or is extremely small). Since the speed reduction ratio of the speed reducer is set to an integral multiple, the ripple periods of the power transmission torque ripples of the speed reducers match and are synchronized, so that dot images of each color can be formed more clearly and superposed.

Further, according to the present invention, particularly when the platen is a roller member, it is possible to easily carry and hold the intermediate transfer medium and to form an image by fusion transfer. Particularly, in the case of a roller, since the adhesion between the intermediate transfer medium and the holding member is good, it is useful for mapping each dot with high accuracy.

Further, according to the present invention, in particular, when the appearance near the heat-generating portion of the thermal head is such that no depression (dent or the like) is present at a position in contact with the substrate film surface of the thermal transfer film (the depression is formed). When the number is small, the effect of smooth and direct heat transfer from the heat generating portion of the thermal head is high. Particularly, when a small diameter dot (corresponding to a highlight portion of an image) is formed, a small amount of heat is transferred to the heat-sensitive transfer film. It is important to conduct heat transfer in a short time and to soften or heat-melt only the small area of the ink layer of the thermal transfer film. Good visualization can be achieved. From this, it is possible to realize dot-on-dot in which good area gradation and color mixing from small dots to large dots and each color are superimposed.

According to the present invention, when a stepping motor driven by an integral multiple of the number of steps of a speed reducer is used as a driving source, for example, a stepping motor is used to move one pitch of dots in the sub-scanning direction. 4 motor steps
Since an appropriate step feed such as step or five steps can be performed in synchronization, the dot positioning accuracy of each color is further improved.

Further, according to the present invention, for example, if a damper for suppressing unnecessary vibration is used for the stepping motor, the alignment accuracy of dots of each color is further improved. Further, by this, in the case of performing "stop hitting" in which the steps are stopped during printing and the melt transfer is performed, the effect of reducing unnecessary vibration between rotation and stop of the stepping motor or the like in a short time is preferable, which is preferable. .

According to the present invention, for example, the configuration of the platen for holding the intermediate transfer medium is devised, and a rigid layer made of a polymer compound is formed on the surface side of the roller. When an elastic layer made of a molecular compound is formed, the vicinity of the heat generating portion of the thermal head does not sink into the thermal transfer recording medium (ink ribbon) side, and good heat transfer can be realized. Since it maintains the accuracy, it is highly effective in performing high-precision color matching of each color. If a holding member such as a so-called rubber simple substance having no rigid layer on the surface is used, the vicinity of the heat generating portion of the thermal head sinks into the thermal transfer recording medium side, and as a result, the heat transfer is performed by the original dot to be transferred. Not only can good dots not be formed because they diverge unexpectedly, but also the intermediate transfer medium can be held with high precision by unnecessary elastic changes or temperature changes of the elastic layer such as rubber. As a result, it becomes difficult to accurately register each color.

Further, according to the present invention, the image receiving layer can be transferred (depending on the layer structure of the intermediate transfer medium, layers other than the image receiving layer may be transferred together), so that the heat generated on the transfer receiving body is reduced. Good image formation can be achieved with a relatively small amount of heat and temperature, which is convenient in terms of device design.In addition, the number of other components can be reduced and the size of the image forming device can be reduced, the mechanism can be simplified,
This is advantageous for cost reduction. The transferred image receiving layer also serves to protect the image.

Further, according to the present invention, an image can be provided on an object to be transferred together with an image receiving layer and the like, including a base film of an intermediate transfer medium, by punching. It is also preferable that a protective layer can be easily provided.

In general, according to the present invention, when transfer recording is performed on the intermediate transfer medium, the drive system of a holding member such as a platen roller for holding the intermediate transfer medium and the thermal head as a writing device are improved. It is possible to provide an image forming apparatus in which dots of almost perfect circles are area-gradated by dot-on-dot [first object]. Further, according to the present invention, a device effective in suppressing fraud such as forgery or falsification, or having an effect of facilitating the discovery of traces of such fraud is provided by thermal transfer when forming an image on an intermediate transfer medium. It can be easily applied by image formation,
The second objective was also achieved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus according to the present invention.

FIG. 2 illustrates an example of an image forming apparatus according to the present invention;
Explanatory drawing which shows the deceleration timing of the timing belt which increases torque and reduces speed by decelerating from 1 side to N2 side.

FIG. 3 is an explanatory diagram illustrating a platen roller drive system in an example of the image forming apparatus according to the invention.

FIG. 4 is an explanatory diagram showing an example of transmission of driving of an example of the image forming apparatus according to the present invention. (The number with Z in the figure indicates the number of each tooth.)

FIG. 5 is an explanatory diagram showing another example of transmission of driving of an example of the image forming apparatus according to the present invention. (The number with Z in the figure indicates the number of each tooth.)

FIG. 6 is an explanatory diagram showing a state in which micro characters are formed by dots in an example of the image forming body according to the present invention. (In the figure, the horizontal direction is the main scanning direction D1, and the vertical direction is the sub-scanning direction D.
2. )

FIG. 7 is an explanatory view showing another example in which micro characters are formed by dots in an example of the image forming body according to the present invention. (In the drawing, the horizontal direction is the main scanning direction D1, and the vertical direction is the sub-scanning direction D2. The resolution in the sub-scanning direction D2 is higher than in the case of FIG. 7.)

FIG. 8 is an explanatory diagram showing a state in which a pattern for generating interference fringes is formed by dots in an example of the image forming body according to the present invention. (In the figure, the horizontal direction is the main scanning direction D1 and the vertical direction is the sub-scanning direction D2.)

[Explanation of symbols]

1, 1 '... Transfer object 2, 2' ... Tray 3 ... Rails 4, 4 ', 5, 5' ... Wheels 6・ ・ ・ ・ ・ ・ Intermediate transfer medium 7 ・ ・ ・ ・ ・ ・ Ink ribbon 8,9 ・ ・ ・ ・ ・ ・ ・ ・ ・ Clamp roller 10 ・ ・ ・ ・ ・ ・ ・ ・ ・ Platen roller 11 ・ ・ ・ ・ ・ ・ Registration Mark sensor 12 Cleaning roller 13, 15, 16, 39 Guide roller 17, 18 Transport roller (rotation direction Dh when advancing) 20, 19 ····· Conveying roller (rotation direction Dd if advancing) 21 ····· Temperature sensor 22 ····· Cleaning roller 23 ····· Supply reel 24 ··· .... Take-up reel 25 ..... Cleaning roller 26 ······ Supply reel 27 ······ Take-up reel 28, 29 ······ Transport roller 28 (rotational direction Dg when advancing) 30, 31 ····・ Sensor 32,33 ・ ・ ・ ・ ・ Cleaning roller 34 ・ ・ ・ ・ ・ ・ ・ Guide roller 35 ・ ・ ・ ・ ・ ・ ・ Peel plate 36 ・ ・ ・ ・ ・ ・ ・ Cable (with socket. Thermal head control) 37 Halogen lamp heater 38 Thermal head 40 Heat roller (Descent direction D)
b, rotation direction Di) 41, 42... shutter (opening direction Dc, Dc ') 50... stepping motor 51, 52. ····· Belts 54,57 ····· Belts 55,56,58,59 ··· Pulley 60 ······ Electromagnetic clutch 100,101 ····· Optical sensor (projection Section and light receiving section)
N1, N2: Deceleration timing of the timing belt (deceleration from N1 to N2) V1, V2: Position shift (N1, N, respectively)
2) Da: The transport direction of the intermediate transfer medium (forward direction) Df: The transport direction of the ink ribbon (forward direction)

Claims (15)

[Claims] 1. A thermal transfer ribbon having a plurality of ink layers of different colors including a color material selected from the group consisting of pigments and dyes, and a long film-like intermediate member capable of transferring said ink layer from said thermal transfer ribbon. An image forming apparatus using: (a) a platen for holding the intermediate transfer medium when transferring the ink layer from the thermal transfer ribbon onto the intermediate transfer medium; and (b) driving. A drive mechanism for driving the platen, comprising: a source; and a transmission member interposed between the drive source and meshing with each other and having a reduction ratio of an integral multiple. A heating section having a substantially circular shape, and selectively heating the thermal transfer ribbon in a state where the intermediate transfer medium and the thermal transfer ribbon are overlaid on the platen, thereby selectively forming the ink layer. Intermediate rotation (D) driving the thermal head in cooperation with the driving of the platen by the driving mechanism based on the image information to thereby transfer the recorded image including the gradation image to the intermediate transfer; Control means for forming on a medium, wherein the gradation image is formed of a group of dots of different colors by the ink layer, and the different colors of dots are stacked at substantially the same position, so that a set color is (E) the intermediate transfer medium on which the recorded image is formed,
A heating and pressurizing means for transferring the recorded image from the intermediate transfer medium onto the transferred object by superimposing the transferred object and applying heat and pressure thereto; and (a) to (e) An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein the intermediate transfer medium has at least an image receiving layer on a base film, and the recorded image is formed on the image receiving layer and transferred onto the transfer receiving body together with at least the image receiving layer. The image forming apparatus according to claim 1, wherein: 3. The method according to claim 1, wherein the intermediate transfer medium heated and pressed by the heating and pressurizing means and the transferred body are punched out along the contour of the transferred body, thereby punching out the intermediate transfer medium. 2. The image forming apparatus according to claim 1, further comprising a punching unit that shifts a recording image onto the transfer target together with a punched portion of the intermediate transfer medium. 4. The image forming apparatus according to claim 1, wherein the recording image formed on the intermediate transfer medium further includes a binary image. 5. An image forming apparatus according to claim 1, wherein said driving source is a stepping motor driven by said transmission member at a step number of an integral multiple of a reduction ratio. apparatus. 6. A heat-sensitive transfer ribbon having a plurality of ink layers of different colors including a color material selected from the group consisting of pigments and dyes, and a long film-like sheet capable of transferring said ink layer from said heat-sensitive transfer ribbon. An image forming method using an intermediate transfer medium, wherein (h) the thermal transfer ribbon is placed on a platen based on image information in a state where the intermediate transfer medium and the thermal transfer ribbon are overlaid on a platen. Is an image forming step of forming a recorded image including a gradation image on the intermediate transfer medium by repeating an operation of selectively heating the color image for each color. Having a set color by stacking dots of different colors formed in a set of dots at substantially the same location, and a driving mechanism of the platen includes a driving source, Using a transmission member interposed between the source and the platen, meshing with each other, and having a reduction ratio of an integral multiple, (i) the intermediate transfer medium on which the recorded image is formed,
A heating and pressurizing step of transferring the recorded image from the intermediate transfer medium onto the transferred object by superimposing the transferred object and applying heat and pressure thereto; An image forming method comprising: 7. The intermediate transfer medium has at least an image receiving layer on a base film, and the recorded image is formed on the image receiving layer and transferred onto the transfer receiving body together with at least the image receiving layer. The image forming method according to claim 6, wherein: (8) The intermediate transfer medium heated and pressurized by the heating and pressurizing means and the object to be transferred are
A punching step of punching the intermediate transfer medium along the contour of the transfer target to transfer the recorded image onto the transfer target together with the punched portion of the intermediate transfer medium. The image forming method according to claim 6. 9. The image forming method according to claim 6, wherein the recording image including the gradation image formed on the intermediate transfer medium in the image forming step further includes a binary image. Image forming method. 10. The image forming step includes the steps of:
7. The method according to claim 6, further comprising the step of forming micro-characters using any one of a group consisting of letters, numbers, symbols, marks, and patterns by using a set of dots by the ink layer. 9. The image forming method according to any one of items 8. 11. The image forming step includes forming, as the binary image, a pattern that generates interference fringes when the recorded image is read by a scanner, using a set of dots formed by the ink layer. The image forming method according to claim 9, further comprising: 12. An image forming body, comprising: a base material; a recorded image; and a transparent resin layer disposed on the base material so as to cover the recorded image visually. The recorded image includes a gradation image and a binary image, and the gradation image is formed of a set of dots of different colors by the ink layer, and a color set by stacking dots of different colors at substantially the same location. Wherein the binary image includes micro-characters formed by the group of dots and using any one selected from the group consisting of letters, numbers, symbols, marks, and patterns. Image forming body. 13. The image forming body according to claim 12, wherein the micro characters are individual information related to a main part of the recorded image. 14. An image forming body, comprising: a base material; a recorded image; and a transparent resin layer disposed on the base material so as to cover the recorded image visually. The recorded image includes a gradation image and a binary image, and the gradation image is formed of a set of dots of different colors by the ink layer, and a color set by stacking dots of different colors at substantially the same location. An image forming body, comprising: a pattern formed by the group of dots, the pattern forming an interference fringe when the recorded image is read by a scanner. 15. A pattern according to claim 14, wherein said pattern for generating interference fringes is a pattern formed such that thin lines extending in a plurality of different oblique directions are formed by dots formed at a high resolution pitch. The image-formed body according to item 1.