JPS6253889A - Thermal transfer copying method - Google Patents

Abstract

PURPOSE:To reduce energy consumption for heating an ink, by providing a light-absorbing member on the side of an intermediate transfer body opposite to an ink image side, when laying a transfer body on the ink image side of an intermediate transfer body and heating through exposure to light, after obtaining the ink image on the intermediate transfer body as a mirror image of an original. CONSTITUTION:A film form light-absorbing member 22 is laminated on the side of an intermediate transfer body 12 opposite to an ink image 12a side, and is pressed against the body 12. The light-absorbing film 22 comprises a light-absorbing layer 24 on a base 23, which may be a thin film of a synthetic resin. The light-absorbing layer 24 may be constituted of carbon black. Exposure light (b) from a light source 21 is absorbed by the light-absorbing layer 24 of the member 22, resulting in heat generation in the layer. The heat (a) thus generated is transmitted to the ink image 12a through the intermediate transfer body 12 to contribute to melting of the ink image. As a result, energy consumption can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a thermal transfer copying method using a heat-melting ink sheet.

(Prior Art) Conventionally, there is a method shown in FIGS. 11 and 12 as a method of copying an original image by a thermal transfer method. In this method, as shown in FIG. 11, an original 1 and a transfer paper 5 as a transfer medium are brought into close contact with each other with an ink sheet 4 in between, and as shown in FIG. etc. are exposed.

When the light beam from the light source 6 is absorbed by the image area 3 (FIG. 11) of the original 1, the armpit area generates heat, and this heat generation melts the ink on the ink sheet 4 in the corresponding area and transfers it onto the transfer paper 5. transcribed.

In this conventional method, the light and heat from the light source 6 must pass through the original 1, so it is not possible to copy originals with images printed on both the front and back sides (double-sided originals), books, etc. There is a drawback. Further, in the case of a thick original, the heat generated in the image area 3 is easily diffused, and as a result, there is a drawback that a clear copy image cannot be obtained.

In order to eliminate these drawbacks, the present inventors created the following first invention, which has not yet become publicly known.

This first invention is a copying method having the following first step and second step.

In the first step, an original is placed on the ink support side of an ink sheet that includes a heat-melt ink layer and an ink support that supports the heat-melt ink layer, and an intermediate transfer member is placed on the ink layer side of the ink sheet. Each layer is laminated and the ink layer is selectively melted by exposure to light.

This is the process of obtaining an ink image that is a mirror image of the original on the intermediate transfer member.

The second step is a step in which the transfer body is placed on the ink image side of the intermediate transfer body, further heated, and the ink image is transferred to the transfer body.

In the first step, the exposure light is not passed through the document as in the past, but is applied directly to the document image surface through an ink sheet, so the document image can be imaged regardless of the shape, thickness, etc. of the document. It is now possible to copy.

In connection with the above-mentioned first invention, the present inventors have also created the following second invention, which is particularly improved in the second step. This second invention is also not publicly known.

The second invention attempts to heat the ink image by exposing the overlapping intermediate transfer member and transfer member to light when heating the ink image in the second step of the first invention.

As a method for heating an ink image, in addition to the second invention, there is also a method in which a layered intermediate transfer member and transfer member are passed between heated rollers, and the ink image is heated by the heat from the rollers. However, with this method, the time required for heating is relatively long, and as a result, there is a risk that "bleeding" of the image may occur due to the melted ink flowing out.

On the other hand, according to the second invention, since the ink image is thermally transferred in a short time by exposure, "bleeding" of the transferred image can be prevented.

As described above, according to the second invention, it is possible to obtain an exceptional effect that has not been seen before, but on the other hand,
Since exposure is performed in both the first and second steps, there is a problem in that a large amount of energy, generally electric power, is consumed for exposure.

(Objective) In view of the above points, the present invention provides a thermal transfer copying method having a first step and a second step comprising the above-mentioned constituent elements.
It is an object of the present invention to provide a copying method that reduces exposure energy for heating ink, and thus reduces energy consumption.

(Structure) The above object is achieved by the present invention having the following structure. In other words, in the present invention, an original is placed on the ink support side of an ink sheet that includes a heat-melt ink layer and an ink support that supports the heat-melt ink layer;
A first step of laminating the intermediate transfer bodies on the ink layer side of the document and selectively melting the ink by exposure to obtain an ink image that is a mirror image of the original on the intermediate transfer body; and the ink image side of the intermediate transfer body. and a second step of heating the transfer body by overlapping the transfer body to transfer the ink image to the transfer body, and the heating of the ink image in the second step is performed by exposure, and during the exposure, the ink image on the intermediate transfer body is heated. This thermal transfer copying method is characterized in that a light-absorbing member is provided on the side where there is no light-absorbing member.

Hereinafter, the present invention will be explained based on Examples.

- FIG. 1 is a diagram for theoretically explaining the copying method according to the present invention, particularly the first step thereof. In the figure, an intermediate transfer body 12, an ink sheet 15, and a document 16 are stacked on top of each other in this order when viewed from a light source 11. In the figure, for illustrative purposes, each member is shown spaced apart from each other by m distances.

In reality, these are pressed from above and below in FIG. 1, and brought into close contact with each other so that no air pocket-like gap is formed between them.

The ink sheet 15 is formed by supporting an ink layer 14 by an ink support 13, and the ink layer 14 is overlapped with the intermediate transfer member 12, while the ink support 13 is overlapped with the original 16. The original documents 16 are stacked so that the image portion 16a to be copied is on the ink sheet 15 side.

When the intermediate transfer member 12 and the like are exposed by the light source 11 in this state, the light ray α from the light source 11 passes through the intermediate transfer member 12 and the ink sheet 15 and reaches the original 16 . This light ray α that has reached the original 16 is exposed to the background part (for example, white) of the original 16.
Then, part of the light is scattered like γ, and the other part is transmitted like γ', and neither part generates heat. On the other hand, 1
In the image area (for example, black) 16a, the light ray α is absorbed and heat generation occurs.

The heat β generated in the image area 16a is transferred to the ink support 1
3 to the ink layer 14 and melts the ink in the portion facing the 1 image portion 16a. This melted ink 1
7 is transferred to the intermediate transfer body 12 in close contact to form a mirror image of the image portion 16a. The above is the first step.

Next, the intermediate transfer body 12 on which the ink image 12a, which is a mirror image, is formed is peeled off from the ink sheet 15, and as shown in FIG. Certain sheets 18 (for example, plain paper) are overlapped and exposed to light by a light source 21. This exposure generates heat in the ink image 12a, and the ink image is thermally melted and transferred onto the transfer member 18 by this heat generation.

As a result, a copy image corresponding to the original image is obtained on the transfer body 18. This is the second step in another invention by the inventor, which is the basis of the present invention. The second step in the present invention is an improvement on this, and will be described in detail later.

In the copying method described above, the light sources 11 and 21 are preferably flash light sources such as xenon lamps capable of short-time exposure in order to prevent unnecessary diffusion of the generated heat.

As for the exposure method, instead of exposing the entire surface of the original 16 or the intermediate transfer member 12 in a single exposure, the surface of the original may be divided into several areas and each area may be exposed sequentially. Further, a curved reflector, a multifaceted reflector, a lens, etc. are arranged around the tubular light source to form an exposure slit in which the light rays from the light source 11 and 21 are converged, and by moving this slit, the surface of the document is A pseudo flash exposure method in which the entire surface is scanned with light may also be used. According to this method, it is possible to successively expose a fixed area to high energy light for short periods of time.

As the ink sheet 15, a thermal transfer ink sheet that has been used in printers and the like in recent years can be used as is. This general ink sheet is made of polyester 3
An ink layer 14 of about 1 to 6 .mu.m, which is made by dispersing dye or pigment in heat-melting wax, is provided on an ink support 13 of about 10 .mu.m. The lower limit of the softening point of the ink layer 14 is 70 to 90°C.

In addition, since the color tone of the ink and the wavelength of light are closely related to this ink layer 14, dye-type ink, which absorbs less long-wavelength components of light, is generally better than pigment-type ink. preferable. For example, black pigments such as carbon black are undesirable for black ink because they have a high absorption rate for long wavelength components, and cyan is a dye color that absorbs only in the visible range.

A mixture of three colors, magenta and yellow, is preferably used.

As the intermediate transfer member 12, a sheet of polyethylene, terephthalate, polypropylene, polyethylene terephthalate, polyvinyl chloride, polyvinylidene chloride, nylon, or other material is used. In terms of characteristics, it is preferable to use a thin layer with high transmittance for long wavelength light and low thermal diffusion and heat insulation properties. Considering practicality such as operability and cost, 10 to 200μ
Further, the thickness is desirably about 40 to 60 μm. As an extreme example, a glass plate several tens of times thicker can also be used.

The exposure energy required to melt the ink varies greatly depending on the size of the original 16, the image density, the materials of the original 16 and the ink, the long wavelength absorption rate of the ink sheet 15 and the intermediate transfer body 12, etc. be done. Generally, it is considered that 500 to 2000 joules is sufficient for an A4-sized document, but as will be described later, according to the characteristic configuration of this embodiment, this can be kept lower.

When exposing the original 16 in FIG. 1, a reflective plate is placed on the back of the original 16 and around the light source 11, so that the light transmitted through the white part of the original 16 and reflected and scattered by the cover is reflected again. The light can be reflected by the plate and reach the image area 16a of the original 16 again. In this way, it is possible to improve energy efficiency.

In the first step, from the ink sheet 15 to the intermediate transfer body 1
The amount of ink transferred to 2 depends on the difference in ink adhesion. Ink sheet 1 from intermediate transfer body 12
When removing the ink sheet 5, as shown in FIG. 3, if the ink sheet 15 is bent at an acute angle, the image is less likely to deteriorate and a stable ink image can be easily obtained.

When copying an original with an image on only one side (a so-called single-sided original), the light source 11 exposes the original 1 in the first step.
It can also be done from the 6th side.

According to the above configuration, light and heat are applied to the document in the first step.
6, the exposure energy from the light source 11 reaches the image 16a without being influenced by unstable factors such as the material and thickness of the original 16. or.

Even if there is an image on the back side of the original 16, it does not affect copying of the image on the front side of the original 16. Furthermore, the ink support 13 of the ink sheet 15 is interposed as a heat transfer layer.
Moreover, this ink support 13 is a thin layer. Therefore, it is possible to minimize image deterioration due to heat diffusion in the heat transfer layer.

In the second step, since the transfer is performed from the intermediate transfer body 12 in the first step, the form of the original 16 is not restricted;
Also, copies can be obtained anywhere. Booth transfer body 1
It is also possible to weld the two together into a laminate, and it is also possible to weld it to a foam or the like.

Since copying is performed via the intermediate transfer body 12, it is possible to delete unnecessary information (unnecessary parts, dirt, etc.) at the stage of moving from the first step to the second step. Furthermore, it is possible to perform intermediate checks on image content and image quality, and to re-edit images without damaging the original.

If a transparent sheet is used as the intermediate transfer body 12, alignment becomes easy.

In this way, the first step shown in FIG. 1 and the second step shown in FIG.
The above-mentioned effects can be obtained through the process. However, since both processes require exposure to heat the ink, there is a problem in that a relatively large amount of energy for exposure, for example, electric power to be supplied to the light source, is required.

Particularly, as is clear from FIG. 1, in the first step, heat is generated in the image area 16a of the original 16 by the light transmitted through the ink sheet 15. Therefore, the ink sheet 15 needs to transmit light of a specific wavelength, and therefore, an ink sheet containing carbon black in the ink layer 14 cannot be used.

In the second step, the ink forming the ink M14 forms an ink image 12a on the intermediate transfer body 12, as shown in FIG.
As a result, it is exposed to light from the light source 21. Originally,
It is desired that all of this exposure light be absorbed by the ink image 12a and converted into heat, contributing to the melting of the ink. However, as mentioned above, since the ink forming the ink image 12a transmits light in a specific wavelength range, a part of the irradiated light α passes through the ink image 12a like the light ray δ, and is wasted. The light ray α' is irradiated onto a portion of the ink image 12a, and this light ray α' transmitted through the intermediate transfer body 12
' is the transmitted light δ' when the transfer body 18 is translucent;
On the other hand, if the transfer member 18 is white and highly reflective, such as plain paper, the reflected light will be scattered as shown by δ'.

In this example, in order to effectively utilize the transmitted light δ that was wasted in the second step as shown in FIG.
As shown in the figure, a film-like light-absorbing member 22 is laminated on the surface of the intermediate transfer body 12 where the ink image 12a is not present (that is, the surface on the light source 21 side), and is further pressed into close contact with the surface. The light-absorbing film 22 has a light-absorbing layer 24 provided on a support 23. As the support 23, a thin film made of synthetic resin can be used. Carbon black can be used as the light absorption layer 24.

As a manufacturing method, carbon black is coated on the support 23 by baking, or dispersed in a solvent or wax.

In FIG. 4, the irradiated light from the light source 21 is absorbed by the light absorption layer 24 of the light absorption member 22, and the layer generates heat. This heat is transferred to the ink image 12a via the intermediate transfer member 12, and contributes to melting of the ink image. In this way, according to this embodiment, even though the ink layer 14 itself is semi-transparent,
The light from the light source 21 can be reliably converted into heat. As a result, reduction in energy consumption can be achieved.

The general characteristics of the intermediate transfer body 12 have been described above, but as described above, in the second step, the intermediate transfer body 12
plays a role as a heat transfer layer, so it is desirable that it has high thermal conductivity. For this purpose, it is preferable to form a thin layer with a thickness of about 3 to 6 μm, for example.

The light absorption layer 24 is not limited to the above carbon black. It suffices to have an absorption region only within the wavelength range of light that passes through the ink image 12a. This is because heat transfer loss occurs even if the light absorbing member 22 is a thin layer, so the loss is smaller when the ink image 12a absorbs light of a wavelength that can be absorbed by the ink image 12a.

FIG. 5 is a graph showing the results of exposing and heating the ink image 12a for each of the states shown in FIGS. 2 and 4. FIG. The horizontal axis is the exposure energy per unit area,
The vertical axis indicates the ratio of the amount of ink transferred from the intermediate transfer member 12 to the transfer member 18 (plain paper). The ink used was a commercially available magenta wax type ink film. The thickness of the intermediate transfer member 12 is 6 μm, and the step of forming the ink image 12a thereon is based on the first step shown in FIG.

Curve A in the figure shows the state shown in FIG. 2, that is, when the transfer was performed without using a light-absorbing member, and curve C shows the state shown in FIG. The transfer was performed using a wax-type ink film, and curve B is the state shown in FIG. 4, in which the transfer was performed using a commercially available black wax-type ink film as the light-absorbing member 22. It is something that

As is clear from the figure, when the black (B) light absorbing member 22 is used, the desired transfer can be performed with approximately 1/2 the energy, and even when the cyan (C) light absorbing member 22 is used, the desired transfer can be performed with approximately 1/2 the energy.
A 30% energy reduction is achieved.

Although not an embodiment of the present invention, there is a method shown in FIG. 6 as a means for heating the ink image 12a in the second step. In this method, the intermediate transfer body 12 and the transfer body 18, which are superimposed on each other, are passed between a heating roller 19 having a built-in heater lamp 19a and a pressure roller 20, and during this passing process, the ink on the intermediate transfer body 12 is Image 12a is transfer body 1
A copy image corresponding to the original image is obtained on the transfer body. There is also a method of heating using an iron instead of a heating roller.

However, in heating using a heat roller, generally 10-odd m5
It takes a heating time of 100 m5 ec to several 100 m5 ec, whereas when an iron is used, it takes several seconds. If the ink image is heated for a relatively long period of time in this way, there is a risk that the ink image will flow out and cause "bleeding" of the image. On the other hand, according to this embodiment in which the ink image 12a is heated by exposure in the second step, the heating work can be completed within a short time, and as a result, the image " It can prevent "bleeding".

Through the above explanation, the thermal transfer copying method according to the present invention has been understood in principle. Next, a description will be given of an apparatus that actually utilizes the method of this invention, that is, a copying apparatus.

FIG. 7 is a perspective view of a portable copying device 51, which is an example of such a copying device. As shown in the figure, the portable copying device 51 includes, from the top of the device, an electrical control section 52 that incorporates electronic components on a board, an operation section 53 such as a display lamp switch,
It has a charging part 54 mainly consisting of a capacitor etc. that stores the light emission energy of a flash lamp, a light emitting part 55 having a flash lamp 11 as a light source, a reflecting plate 82, etc., and a translucent platen plate 61, a translucent buffer member 62, etc. Translucent platen portions 56 are arranged in a stacked manner.

The translucent platen portion 56 is as shown in FIG.

This is the part that presses the original 16 and the transfer sheet 77 when they are brought into close contact with each other. The transfer sheet 77 is previously formed integrally by bringing the intermediate transfer body 12 and the ink sheet 15 into close contact with each other, as shown in FIG. As explained in connection with FIG. 1, the ink sheet 15 is made up of the ink support 13 and the ink layer 14 supported thereon. Intermediate transfer body 12 and ink sheet 15
A frame 75 is used between the two as necessary. The frame 75 is placed around the intermediate transfer body 12 as shown in FIG.

In FIG. 10, first, a transfer sheet 77 is placed on l@i16 to be copied so that the ink sheet 15 side faces the original 16 side. The portable copying device 51 is placed thereon so that the platen portion 56 is in close contact with the transfer sheet 77. The copying device 51 is connected to a power source such as a commercial 100V power source or a rechargeable battery, and the flash charging capacitor is charged to a preset potential level by this power source.

Due to the weight of the copying device i51 and the pressure applied through the copying device 51, the platen portion 56 of the copying device 51 and the transfer sheet 7
7, and each of the originals 16 is uniformly pressed and brought into close contact with each other. When the flash lamp trigger switch is turned on in this state, the flash lamp 11 emits light and the original 16 is exposed through the platen section 56 and the transfer sheet 77.

The details of the subsequent copying work are the same as those described in connection with FIGS. 1 to 4.

(Effects) According to the present invention, in the second step, light is converted into heat by the light-absorbing member, and the heat is used to convert the light into heat.

Since the ink images on the eight transfer bodies were heated, the energy of light was efficiently utilized as thermal energy, and as a result, the exposure energy could be reduced.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the principle of the first step of the copying method according to the present invention, FIG. 2 is an explanatory diagram showing the second step of the copying method according to another invention which is the basis of the present invention, and FIG. An explanatory diagram showing the method of peeling off the intermediate transfer member and the ink sheet in the copying method according to the present invention, FIG. 4 is an explanatory diagram showing the principle of the second step of the method of the present invention, and FIG. A diagram showing the relationship between exposure energy and transfer rate, FIG. 6 is an explanatory diagram of related technology for the second step, FIG. 7 is a perspective view of an example of a copying apparatus for carrying out the method of the present invention, and FIG. 8 9 is a side sectional view of a transfer sheet used in this copying device, FIG. 9 is a perspective view of this transfer sheet, FIG. 10 is an explanatory diagram of how to use this copying device, and FIGS. 11 and 12 are a conventional copying method. FIG.

Claims (1)

[Scope of Claims] An original is placed on the ink support side of an ink sheet that includes a heat-fusible ink layer and an ink support that supports the hot-fusible ink layer, and an intermediate transfer member is placed on the ink layer side of the ink sheet. They are laminated and the ink is selectively melted by exposure to light.
The method includes a first step of obtaining an ink image that is a mirror image of the original on the intermediate transfer member, and a second step of stacking the transfer member on the ink image side of the intermediate transfer member and heating it to transfer the ink image to the transfer member. A thermal transfer copying method, characterized in that the ink image in the second step is heated by exposure, and during the exposure, a light-absorbing member is provided on the side of the intermediate transfer body where there is no ink image.