JPH0714646B2 - Halftone image forming method and transfer recording medium for halftone image formation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming method capable of expressing a halftone used in a copying machine, various printers, etc., a transfer recording medium used in this direction, and The present invention relates to an image forming apparatus using the method.

[Prior Art] In recent years, along with the rapid development of the information industry, various information processing systems have been developed, and recording methods and apparatuses suitable for the respective information processing systems have been developed. There is a thermal transfer recording method as one of such recording methods. This method is widely used recently because the apparatus used is lightweight and compact, has no noise, and is excellent in operability and maintainability. .

This recording method generally uses a heat-sensitive transfer medium obtained by applying a heat-transferable ink having a colorant dispersed in a hot-melt binder on a support on a sheet, and the heat-sensitive transfer medium is used as the heat-transferable ink. The layer is superposed on the transfer medium so that the layer contacts the transfer medium, and heat is supplied from the support side of the heat-sensitive transfer medium by a thermal head or the like to transfer the melted ink layer to the transfer medium, thereby forming a heat supply pattern. A corresponding transfer recording image is formed on the transfer medium.

According to this method, plain paper can be used as the transfer medium.

[Problems to be solved by the invention]

However, such a conventional thermal transfer recording method is not without drawbacks. In the conventional thermal transfer recording method, the transfer recording performance, that is, the image quality is greatly affected by the surface smoothness of the transfer medium, and good printing can be performed on the transfer medium having high smoothness, but the smoothness is low. This means that the print quality is remarkably deteriorated in the transferred medium. Moreover, even the most common transfer medium, paper with high smoothness is rather special, and ordinary paper has various degrees of unevenness due to the entanglement of fibers. Therefore, in the case of paper with large surface irregularities, the heat-melted ink cannot penetrate into the fibers of the paper at the time of printing and adheres only to the convex parts of the surface or its vicinity, resulting in sharp edges of the printed image. Or the image was partially cut off and the print quality deteriorated.

Further, the transfer of the ink layer to the transfer medium is performed only by the heat from the thermal head, but generally the amount of heat that can be supplied from the thermal head is limited, and a large amount of recording signal is generated within a limited time. In order to convert and supply as a pulse, in order to prevent a time lag of cooling to a predetermined temperature within the heat pulse of the thermal head at the time of recording, and also a thermal stroke between the heat generating segments forming the thermal head surface. Moreover, theoretically, it was difficult to increase the amount of heat supplied from the thermal head. Therefore, high-speed recording is difficult with the conventional thermal transfer recording method.

Furthermore, heat conduction has a slower response response than electricity or light, so it is generally difficult to control the heat pulse until halftone can be reproduced when recording with a thermal head. The heat-sensitive transfer ink layer of No. 1 does not have transfer characteristics capable of expressing gradation. Therefore, it has been impossible to directly control the heat pulse and adjust the shading of the recorded image to express a halftone.

On the other hand, in the conventional thermal transfer recording method, from the viewpoint of the recording characteristics as described above, normally, only one binary expression (whether or not to print) can be expressed in one recording pixel, and a multi-step recording is performed in one recording pixel. Since it is not possible to express density gradation, when expressing halftones with this recording method, a matrix composed of a plurality of pixels is used as an image recording unit, and printing is to be recorded at each pixel forming the matrix. A so-called area gradation method has been mainly used in which halftones are expressed by controlling according to the shading of an image.

However, when such an area gradation method is used, it is difficult to obtain a good resolution.

That is, the resolution of an image is basically inversely proportional to the size of a matrix, which is a constituent unit of a recorded image, and in the thermal transfer recording by the conventional area gradation method, the halftone by the density gradation divided into more stages is produced. In order to express, the number of pixels forming the matrix must be increased. Moreover, since there is a limit to reducing the size of the pixel, the size of the matrix itself is inevitably increased, which exceeds the range suitable for obtaining good resolution.

On the other hand, one recording unit of a recorded image is expressed by one pixel, and one recording pixel enables multi-stage density gradation expression. In recent years, a thermal transfer recording method using a sublimation transfer type transfer recording medium for directly controlling the deposition amount of
It has a drawback that a special recording paper (transferred medium) must be used.

The present invention is a halftone image forming method that solves the problems of the above-mentioned conventional thermal transfer recording method, that is, high-speed recording is possible, halftone can be expressed with high resolution, and the surface smoothness is the lowest. It is a principal object of the present invention to provide a halftone image forming method capable of forming a high-quality transfer image even on a commonly used plain paper and a transfer recording medium used in the method.

[Means for solving problems]

The above object can be achieved by the present invention described below.

The present invention is characterized in that (a) it has a transfer recording layer in which two or more kinds of image-forming element bodies having different energy application conditions that change the physical properties that govern the transfer characteristics are mixed in a predetermined different mixing ratio. (B) a transfer image is formed on the transfer recording medium by applying two or more kinds of energy to the transfer recording medium under conditions corresponding to the optical density exhibited by the image forming element according to the recording information. Forming process,
And a step of transferring the transfer image to a transfer medium, which is a halftone image forming method.

That is, in the halftone image forming method according to the present invention, the transfer image forming step and the transfer step are separated, and the transfer image is already formed in the transfer step. Therefore, the restriction of selective energy application for image formation is released. Therefore, it is possible to apply the necessary and sufficient energy to the transfer recording medium in order to transfer a clear image, depending on the surface properties of the transfer medium. In addition, the transfer image formed in the previous step is not a mere property change image such as a heat fusion image, but an image formed by changing the physical properties that govern the transfer characteristics of the transfer layer. By using the difference in the transfer step, the transfer can be surely realized, and the transfer image can be faithfully transferred. For example, when a heat-melted image is used as a transfer image, it is necessary to completely maintain the heat-melted image from the transfer image forming step to the transfer step. However, a decrease in transferability due to a cooling phenomenon between both steps, Image blurring due to heat conduction to the periphery of the heat-melted image is inevitable. However, in the case of the present invention, the physical properties that govern the transfer characteristics, for example, the melting point, the softening point, the viscosity at the same temperature, etc. of the image forming element in the transfer recording layer are changed to form a transferred image. Is stored up to the transfer step, so that the transferability of the transferred image and image blurring do not occur unless energy for changing the physical properties is applied after the transfer image forming step. Further, even if the surface smoothness of the transferred medium is low, the transfer process can be independently performed under the conditions adapted to the surface smoothness, and it is possible to form an image with high image quality, and the image quality of the transferred image does not deteriorate. It can be transferred to a medium to be transferred.

Further, in the halftone image forming method according to the present invention, the application of signalized energy for transfer image formation and the uniform application of energy for transfer are functionally separated from each other. Compared with the case where the signalized energy for is simultaneously used as the energy for transcription,
The constraint conditions for energy application are greatly relaxed. For example, the amount of energy for transfer image formation may only cause a change in the physical properties of the transfer recording layer, and the energy for transfer may be a uniform energy that is not signaled, so that the desired transfer It can be increased according to the speed, and high-speed recording can be easily realized.

In the thermal head used in the conventional thermal transfer recording apparatus, the fastest thermal response speed is about 1 to 5 msec, and if it is driven at a repetition cycle faster than that, the temperature rises and falls. The image quality could not be fully achieved within one cycle, and the effect of heat storage appeared on the image quality without insufficient heating or conversely the temperature did not drop. This was one of the most important factors that hampered speeding up, but if a plurality of types of energy are used as in the present invention, for example, if a thermal head and light irradiation are combined, then the transfer characteristics will be governed even in the state where heat is stored. Since the effectiveness of the heating state in changing the physical properties can be set only at the time of light irradiation, by applying light only during a limited time zone near the peak temperature, the temperature after the peak temperature can be reduced as in the past. It becomes possible to make the influence of the descending speed less likely to occur, and even if the conventional thermal head is used, the recording operation can be performed in a shorter repetition period, and high-speed recording becomes easier.

Furthermore, the transfer recording medium of the present invention exhibits a predetermined optical density on the medium to be transferred, and two or more kinds of image forming elements having different energy application conditions that change the physical properties that govern the transfer characteristics have predetermined optical density. It has a transfer recording layer that is mixed on the substrate with different blending ratios, and the conditions for applying energy such as light and heat applied to the transfer recording layer are controlled according to the density of the image to be recorded. Depending on the blending ratio of each image forming element, for example, the transfer number of image forming elements exhibiting the same optical density, or the combination of image forming elements exhibiting different optical densities and the transfer number thereof are controlled. The density gradation of the image to be recorded is expressed by transferring this to the transfer medium.

Therefore, in the method of the present invention, for example, even when a recording unit of an image is represented by one recording pixel, the transfer number of the image forming element exhibiting the same optical density as described above or different optical density 2 is exhibited. Since one recording pixel is formed by controlling the combination of image forming elements of more than one kind and the transfer number thereof, it is possible to directly control the optical density exhibited by one recording pixel, and to extend the above-mentioned area gradation. The halftone can be expressed without lowering the resolution unlike the conventional thermal transfer recording method using the method, and the gradation of the image to be recorded can be faithfully reproduced.

In addition, the image forming method of the present invention basically determines the transfer number of the image forming element having the same optical density as described above.
Alternatively, a method of expressing a halftone by controlling a combination of two or more kinds of image forming elements exhibiting different optical densities and a transfer number thereof according to recording information and transferring the transferred image to a transfer medium, When the transfer image is formed on the recording layer, the conditions of energy to be applied such as heating temperature and time are adjusted stepwise, and the transfer amount per image forming element is controlled to divide the image into multiple stages. It is also possible to express the gradation of the generated light and shade.

Even when the above control is performed, in the image forming method of the present invention, high-speed recording is possible because energy such as light having a fast response response can be used together.

In the halftone image forming method according to the present invention, the transfer image is formed by changing the physical properties that govern the transfer characteristics of the image forming element. The physical properties are arbitrarily set according to the type of transfer recording medium used. For example, in the case of a transfer recording medium in which a transferred image is transferred in a heat-melted state, it is a melting temperature, a softening temperature, a glass transition point, or the like. In the case of a transfer recording medium that is transferred in the penetrating state, the viscosity is the same at the same temperature.

The plurality of types of energy used to form the transferred image are arbitrarily selected depending on the type of the transfer recording medium used, and for example, light, electron beam, heat, pressure and the like are appropriately combined and used.

Therefore, the transfer recording medium of the present invention is configured to have a transfer recording layer whose physical properties governing its transfer characteristics are changed in accordance with two or more kinds of applied energy, such as the one described below. Includes those that have a transfer recording layer that forms a transfer image by changing the physical properties that govern the transfer characteristics of the image forming element by heat and light energy, based on the principle described with reference to FIGS. 1a to 1d. Be done.

Next, the principle of the halftone image forming method of the present invention will be described with reference to FIGS. 1a to 1d, taking as an example the case where a transfer image is formed using light and thermal energy to form an image.

The time axes (horizontal axes) of the graphs in FIGS. 1a to 1d correspond to each other. Also, as a sensitive component in the transfer recording layer,
It contains a polymerizing component including a reaction initiator and a cross-linking agent which will be described later. FIG. 1a shows how the surface temperature of the heating element rises and the temperature drops thereafter when the heating means such as a thermal head is driven to generate heat for a period of O to t ₃ .
The transfer recording medium pressed against the heating element shows a temperature change as shown in FIG. 1b with a temperature change of the heating element. That is, the temperature rises with a time delay of t ₁ , similarly reaches the maximum temperature at a time of t ₄ later than t ₃ , and thereafter the temperature drops. This transfer recording layer has a glass transition point Tg ₀ ,
It rapidly softens and the viscosity decreases in the temperature range of g ₀ or higher. This situation is shown by the curve A in FIG. 1c. After reaching Tg ₀ at time t ₂ , the viscosity continues to decrease until time t _{4 with} respect to the maximum temperature, the viscosity increases again as the temperature decreases, and the viscosity sharply increases until time t ₆ when Tg ₀ decreases. In this case, the physical properties of the transfer recording layer did not basically change from those before heating, and the same change phenomenon of viscosity as described above was exhibited for the first time by heating at the temperature Tg ₀ or higher in the next transfer step. . Therefore, if the transfer recording layer is heated in contact with the medium to be transferred and heated for transfer, for example, Tg ₀ or higher, the transfer recording layer is transferred by a mechanism similar to the transfer mechanism of conventional thermal transfer recording. However, in the case of the present invention, as shown in FIG. 1d, when light is irradiated simultaneously with heating of the transfer recording layer from time t _{2, the} reaction initiator contained in the transfer recording layer is irradiated by light. When activated, the temperature has risen high enough to speed up the reaction,
The reaction initiator acts to generate an activated cross-linking agent, and the probability of cross-linking of the cross-linkable prepolymer is dramatically increased, and the transfer recording layer is cured.

When the heating and the light irradiation are simultaneously performed in this way, the thermal transfer recording layer behaves as shown by the curve B in FIG. 1c. The crosslinking reaction glass transition point increases with advances, crosslinking is changed to Tg 'from time t ₅ the Tg ₀ ends. This is shown in Figure 1d. Therefore, if heated in the next transfer process, T
There is a difference in physical properties (temperature dependence of viscosity) between the part changed to g ′ and the part not changed. Therefore, for example, Tg ₀ <Tr
When heated to a temperature Tr satisfying <Tg ′, a portion where the viscosity is lowered and a portion where the viscosity is not raised are generated, and only the portion where the viscosity is lowered is transferred onto the transfer medium. Although it depends on the temperature stability accuracy of the transfer step, Tg′-Tg _{0 at} this time is preferably about 20 ° C. or higher. In this way, the transfer image can be formed by controlling heating or non-heating according to the image signal and irradiating light at the same time. If the glass transition point changes, the softening temperature and the melting temperature also fluctuate with the same tendency. Therefore, the softening temperature and the melting temperature can be controlled by using the fluctuation range of the glass transition point as a guide.

In addition, the heating temperature in the transfer image forming step is set to 70 ° C. or higher, preferably 80 ° C. or higher for the transfer recording layer in order to accelerate the reaction rate at which the physical properties governing the transfer characteristics change and to carry out the reaction stably. Good results are obtained by heating to a temperature of ℃ or above.

An example of the halftone image forming method of the present invention will be described below with reference to the principle of the image forming method described above.

2a to 2d are schematic views showing the relationship between the transfer recording medium, the thermal head and the light irradiation in the transfer image forming step in the image forming method of the present invention.

In this example, the thermal energy modulated according to the image signal is applied to the transfer recording medium together with the optical energy of the wavelength selected corresponding to the optical density of the image forming element whose physical properties that govern the transfer characteristics are desired to be changed. To be done. Here, “modulation” refers to changing the position where energy is applied according to the image signal, and “together” may be the case where light energy and heat energy are applied simultaneously, or light energy and heat energy may be applied. The energy may be applied separately.

The transfer recording medium 1 for forming a halftone image of the present invention in this example is configured by providing a transfer recording layer 1a on a base film 1b. The transfer recording layer 1a has a predetermined optical density by itself.
Exhibit D _1, that is, the image forming element 1aa-1~1aa-3 when transcribed solely to a transfer medium which can provide an absorbance of D ₁ to the recording unit portion of the transfer medium are mixed It is a layer.

Each image forming element body 1aa contains, for example, a black coloring material (coloring component), and three kinds of image forming element bodies 1aa having different energy application conditions that change the physical properties that govern the transfer characteristics thereof.
-1 to 1aa-3, which are transfer layers 1a in this example.
In addition, it is contained in a compounding ratio of 1aa-1: 1aa-2: 1aa-3 = 1: 2: 3.

The type of each image forming element 1aa and the mixing ratio thereof are not limited as in this example, and may be appropriately selected according to the application of the recording medium.
The color tone and optical density exhibited by are not limited to black and D ₁ , and the type and content of the coloring material are such that the image forming element exhibits cyan, magenta, yellow or other color tone and optical density. May be appropriately selected and used.

In addition, in this example, a transfer recording medium configured to have a transfer recording layer made of an image forming element having the same optical density is used, but the present invention is not limited to this. Without any need, for example, a combination of image-forming elements that exhibit different optical densities according to the energy application conditions for changing the physical properties that govern the transfer characteristics, or the energy application conditions It is also possible to use a transfer recording layer in which image forming elements are mixed in a combination such that two or more of the same materials have different optical densities.

Each image-forming element 1aa has a sensitive component (polymerization component) as described below that changes physical properties that govern its transfer characteristics when light and heat energy is applied in addition to the coloring material.
Contains.

The sensitive components of the three types of image forming elements 1aa-1 to 1aa-3 are appropriately selected so that they have different wavelength dependences on light energy.

That is, the image forming element 1aa-1 (indicated by 1 in the figure) is
When heat and light of wavelength λ ₁ are applied, the crosslinking of the polymerizing component contained rapidly progresses and cures. Further, the image forming element 1aa-2 (indicated by 2 in the figure) receives heat and light of λ ₂ , and the image forming element 1aa-3 (indicated by 3 in the figure) adds heat and light of wavelength λ _3. When it is given, the cross-linking of the polymerizing components contained therein proceeds to cure. In the next transfer step, the cured image forming element 1aa does not decrease in viscosity even when heated and does not transfer to the transfer medium. Heat and light are applied according to the recorded information.

An image can be formed by the image forming method of the present invention as follows using the transfer recording medium having the above-described structure.

First, the transfer recording medium 1 is superposed on the thermal head 20, and light is irradiated so as to cover the entire heating portion of the thermal head 20 while changing the position to which thermal energy is applied according to the image signal. The irradiation light has a wavelength necessary for changing the physical properties that govern the transfer characteristics of the image forming element 1aa. In this example, the image-forming element 1aa is composed of three types, 1aa-1 to 1aa-3, which have different energy application conditions that change the physical properties that govern the transfer characteristics, so that the wavelengths set as described above are accordingly set. λ ₁ , λ ₂ and λ
The light of ₃ is sequentially irradiated.

That is, first, as shown in FIG. 2a, light of wavelength λ ₁ is emitted from the transfer recording layer 1a side of the transfer recording medium 1 and, for example, heat generating resistors 20b, 20c, 20f and 20g of the thermal head 20 are caused to generate heat. . Then, of the image forming element 1aa-1, the image forming element to which both heat and the light of the wavelength λ ₁ is applied (hatched. The cured image forming element is shown by hatching hereinafter. ) Hardens.

Next, as shown in FIG. 2b, the transfer recording layer 1a is irradiated with light having a wavelength λ ₂ , and the heating resistors 20a, 20e, 20f and
When 0 g of heat is generated, the image forming element body 1aa-2 of the image forming element body 1aa-2 to which heat and light of the wavelength λ ₂ are applied is cured. Further, as shown in FIG. 2c, when the heating resistors 20c, 20d, 20e and 20h are heated while being irradiated with light of wavelength λ ₃ , the image forming element body to which light and heat are applied is cured, Finally, a transfer image represented by a density gradation corresponding to the density of the image to be recorded on the transfer recording layer 1a is formed by the image forming element body (without hatching) which is not cured. This transfer image is transferred to the transfer medium 10 as shown in FIG. 2d in the next transfer step.

In the transfer step performed subsequent to the step of forming the transfer image shown in FIGS. 2a to 2c, the transfer recording medium on which the transfer image is formed is brought into contact with the transfer medium, and the transfer recording medium side or the transfer recording medium side is contacted. The image is formed by heating from the transfer medium side and selectively transferring the transfer image to the transfer target medium. The heating temperature at this time is selected so that only the transferred image having the physical properties that govern the transfer characteristics is selectively transferred. It is also effective to apply pressure simultaneously in order to efficiently perform transfer. Pressurization, in particular,
This is effective when a transfer medium having a low surface smoothness is used. When the physical property that governs the transfer characteristic is the viscosity at room temperature, the transfer can be performed only by pressure as the energy applied in the transfer step. Heating in the transfer process
It is suitable for obtaining a stable halftone image that is stable and has excellent storage stability.

In the transfer image thus formed, as shown in FIG. 2d, the number of image forming elements transferred is controlled in accordance with the mixing ratio of each image forming element according to the recorded image information. And is transferred to the transfer medium 10.

That is, the unit portion 10e in which the image forming element body 1aa is transferred alone exhibits the optical density D ₁ as described above, and only one kind of the image forming element body 1aa-2 is transferred in the unit portion 10c, that is, The portion where two image-forming elements have been transferred corresponding to the mixing ratio exhibits an optical density D ₂ , and the image-forming element 1aa-3
The unit portion 10f to which only one of the above is transferred, that is, the portion to which three image-forming elements have been transferred corresponding to the blending ratio has an optical density D ₃ .

Further, in the unit portion 10a to which the image forming elements 1aa-1 and 1aa-3 have been transferred, four image forming elements corresponding to the total of these compounding ratios are transferred, and the optical density D corresponding to this is transferred. _Four
Present. Similarly, in accordance with the image information, seven stages (non-recorded state 10 g according to the number of transfer of the image forming element 1aa-1 to -3 depending on the number of transfer of the image forming element according to the combination of the compounding ratios) Each recording unit of the transfer image is formed by the density gradation of (inclusive), and the transfer image in which the halftone is well expressed is formed.

In the above description, as shown in FIG. 2d, the image forming elements are discretely scattered on the transfer medium (recording paper etc.), but this is for convenience of explanation only. In form,
Actually, the transferred element spreads two-dimensionally on the surface of the medium to be transferred, and as a result, in the example of FIG. 2d, each unit part corresponding to each heating element (20a to 20g) of the thermal head. (10a
Correctly form ~ 10g).

Here, if each unit portion (10a to 10g) is made to correspond to one recording pixel, one recording pixel can be expressed by multiple density gradations, and as described above, the resolution can be reduced to the intermediate level. A toned image can be formed.

For example, according to the image forming method of the present invention, as shown in Table 5 of Reference Example 1 described later, the density of one recording pixel of the image transferred to the recording medium to be transferred is 0.06 to 0.06 in optical density.
It is possible to express up to 1.20 in 16 gradations.

As described above, in the example described in FIGS. 2a to 2d, the method of forming an image by irradiating the entire area of the thermal head 20 with light and selectively heating the heating resistors of the thermal head 20 is shown. Similarly, by heating a portion of the transfer recording medium uniformly (in the case of the thermal head 20 shown in FIG. 2a, all the heating resistors are heated) and selectively irradiating light, A halftone image can be formed. That is, light energy having a wavelength that is modulated according to a recording signal and that is selected according to the optical density exhibited by the image forming element whose physical properties dominate transfer characteristics is desired may be applied together with thermal energy.

Specifically, in the example shown in FIG. 2a, instead of causing the heating resistors 20b, 20c, 20f and 20g to generate heat, the thermal head 20 causes the entire heating element to uniformly generate heat, and the heating resistor 20
The light having the wavelength λ ₁ is applied to the positions corresponding to b, 20c, 20f and 20g. Further, when irradiating with light of wavelength λ _2, the entire thermal head 20 is caused to generate heat, and the heating resistors 20a, 20e, 20
Irradiate the position corresponding to f and 20g. Below, wavelength λ
_The same applies to the case of irradiating the light of ₃ .

In the above description, the thermal head is used for convenience as a means for uniformly heating the whole, but a uniform heating means such as a heat roll or a heating plate may be used.

It should be noted that the present invention is basically based on expressing a plurality of stages of halftones with one recording pixel in order to perform recording with good resolution, but of course, if desired, this pixel is distributed in a matrix to provide multi-gradation. It is possible to further increase the number of gradations by using the method of expressing.

Further, in the transfer image forming method described above, an example in which the image forming element has different spectral sensitivities was shown, but this characteristic is not essential in the present invention. For example, if you use two or more types of materials that have different temperature characteristics and that react to light and heat,
Even if the spectral characteristics are the same, they can be distinguished by the applied thermal energy. In other words, an image forming element body having a temperature dependency is used as the image forming element body, and the image forming element body is uniformly irradiated with light, and thermal energy is added while being changed depending on the recorded information and the optical density exhibited by the image forming element body. It doesn't matter if you do so.

The transfer recording medium of the present invention is a transfer recording medium in which two or more kinds of image forming elements exhibiting a predetermined optical density and different energy application conditions that change the physical properties that govern the transfer characteristics are mixed in a predetermined different mixing ratio. Use of a transfer recording medium having any structure as long as it has a recording layer and can form a transfer image by changing the physical properties of the image forming element according to application of plural kinds of energy. You can

Examples of the combination of the image-forming elements mixed in the transfer-recording layer of the transfer-recording medium of the present invention include, for example, a) a combination in which all the image-forming elements exhibit the same optical density, and b) each image-forming element. A combination in which an element body exhibits different optical densities according to energy application conditions that change the physical properties that control its transfer characteristics, c) Image formation under the same energy application conditions that change the physical properties that control its transfer characteristics A combination in which two or more of the element bodies have different optical densities can be mentioned.

As the transfer recording medium of the present invention, as described above, the physical properties that govern the transfer characteristics are melting temperature, softening point, glass transition point,
Examples of the viscosity and the like include a transfer recording medium in which the image forming element contains a coloring component (coloring material) and a polymerizing component as a sensitive component. In this case, by polymerizing the polymerizing component of the image forming element, the melting temperature and the like increase, and the image forming element that is not polymerized forms a transferred image. The image-forming element contained in the transfer recording layer contains a sensitive component and a coloring component, and the sensitive component is one that initiates a reaction of physical property change when irradiated with light and thermal energy, or It is preferable to use a material whose reaction rate of changes in physical properties changes rapidly.

The polymerizing component is a component that causes a polymerization reaction or a crosslinking reaction, and typical examples thereof include the following monomers or polymers (a) to (c).

(A) Crosslinkable prepolymer, (b) Polymerizable prepolymer and crosslinker, (c) Polymerizable monomer or oligomer, Examples of the crosslinkable prepolymer include polyvinyl cinnamate, p-methoxycinnamic acid-succinic acid. Examples include half-esters, polyvinyl styrylpyridinium, polymethyl vinyl ketone, and the like.

Examples of the polymerizable prepolymer include epoxy resin, unsaturated polyester resin, polyurethane resin, polyvinyl alcohol resin, polyamide resin, polyacrylic acid resin, polymaleic acid resin, and silicone resin.

Examples of the cross-linking agent include ethylene glycol diacrylate, propylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol acrylate, and N, N'-methylenebisacrylamide.

Examples of the polymerizable monomer include methyl acrylate,
Methyl methacrylate, cyclohexyl acrylate,
Benzyl acrylate, acrylamide, methacrylamide, N-methylol acrylamide, N-diacetone acrylamide, styrene, acrylonitrile, vinyl acetate, ethylene glycol diacrylate, butylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6- Hexane diol dimethacrylate etc. are mentioned.

Examples of the polymerizable oligomer include diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol acrylate, polyethylene glycol dimethacrylate, polypropylene glycol diacrylate, and the like.

When a polymerizable monomer or oligomer is used, a polymer such as cellulose acetate succinate or methyl methacrylate-hydroxyethyl methacrylate copolymer may be contained in order to improve the layer forming property.

If necessary, a reaction initiator is added to cause the reaction of the polymerizing component. As the reaction initiator, examples of the initiator acting by light energy include benzophenone, benzyl, benzoin ethyl ether, 4-N,
Carbonyl compounds such as N'-dimethylamino-4-methoxy-4-benzophenone; organic sulfur compounds such as dibutyl sulfide, benzyl disfilled, decyl phenyl sulfide; peroxides such as di-tert-butyl peroxide, benzoyl peroxide Carbon tetrachloride, silver bromide, 2
-A halogen compound such as naphthalene sulfonyl chloride; a nitrogen compound such as azobisisobutyronitrile and benzenediazonium chloride; and the like.

Further, as a substance which receives thermal energy and acts as a reaction initiator, methyl hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, t
-Butyl cumyl peroxide, peroxyacetic acid, peroxybenzoic acid, acetyl peroxide, propionyl peroxide,
Examples thereof include isobutyryl peroxide, acetone peroxide, methyl ethyl ketone peroxide, diazoaminobenzene, dimethyl-2,2'-azoisobutyrate, diphenyl sulfide and benzoyl disulfide.

In particular, when the transfer recording layer is formed by receiving both light and thermal energy, the structure of the transfer recording layer has a temperature of reaction rate due to the reaction between the above-mentioned reaction initiator which acts upon receiving the light energy and the polymer compound. The types of the reaction initiator and the polymerizing component may be selected so that the combination is highly dependent.

For example, a combination of a polymerizable prepolymer having a functional group such as a copolymer of methacrylic acid ester or acrylic acid ester, a photosensitive cross-linking agent such as tetraethylene glycol diacrylate, and a reaction initiator such as benzophenone or Michler's ketone may be used. Can be mentioned.

The coloring component is a component contained to form an optically recognizable image, and various pigments and dyes are appropriately used. Examples of such pigments and dyes include inorganic pigments such as carbon black, brass, molybdenum red and red iron oxide, Hansa Yellow, Benzidine Yellow, Brilliant Carmine 6B, Lake Red C, Permanent Red F5R, Phthalocyanine Blue, Victoria Blue Lake, Examples thereof include organic pigments such as fast sky blue, colorants such as leuco dyes and phthalocyanine dyes.

When the coloring component is contained in the image forming element, for example, depending on the combination of the three types of the image forming element described above, the type of the image forming element may have the same or different optical density. And / or the content is changed.

In addition, the transfer recording layer may contain stabilizers such as hydroquinone, p-methoxyphenol, p-tert-butylicatechol, and 2,2-methylene-bis (4-ethyl-6-tert-butylphenol). good.

Further, sensitizers such as p-nitroaniline, 1,2-benzanthraquinone, p-p'dimethylaminobenzophenone, anthraquinone, 2,6-dinitroaniline, and Michler's ketone are transferred to enhance activation of the reaction initiator against energy. It may be included in the recording layer.

In the transfer recording medium used in the halftone image forming method of the present invention in which light energy is used, at least two kinds of image forming elements mixed in the transfer recording layer at a predetermined different mixing ratio are added to the transfer recording medium. It must have a different wavelength dependence on the applied light energy. For example, when the transfer recording layer is composed of n kinds of image forming elements having different wavelength dependences on light energy, light having a different wavelength for each kind of image forming element, that is, n.
The distribution layer of the image-forming element is constituted by a combination of sensitive components such that the reaction speed changes abruptly with light of different wavelengths. As a combination of such sensitive components, for example, as a sensitizer Something that is sensitive at about 400-500 nm, As described above, it is possible to obtain two types of image forming elements having different wavelength dependences by using a material that is sensitive to light at about 480 to 600 nm. In this case, at least one of the image forming elements
Since these are mixed in the transfer recording layer with different compounding ratios for each type, one recording pixel is selected from the combination of the transfer numbers of the image forming elements according to this compounding ratio, and one recording pixel has at least four kinds of optical density (no recording state That is, it can be expressed in four levels of density gradation.

In this case, the light-sensitive regions of both are regions of low sensitivity although the wavelength regions of 480 to 500 nm overlap, and the two can be almost completely separated by appropriately selecting the light source.

Furthermore, azo compounds and 300
By combining halogen compounds that are sensitive at up to 400 nm, it is possible to use three types of image forming elements having different wavelength dependences, and by transferring these in combination, one recording pixel can be used for at least eight types of optical elements. It can be expressed by the density (including the non-recorded state), that is, the density gradation of 8 steps.

The transfer recording medium used in the present invention can be manufactured, for example, as follows.

The same energy application conditions that change the physical properties that govern the transfer characteristics of the composition components such as polymerizable prepolymers having functional groups, photosensitive crosslinking agents, reaction initiators, sensitizers, stabilizers, and colorants. By the melt mixing method or spray drying method,
It is a minute image forming element. Further, together with a binder such as a polyester resin, two or more kinds of image-forming elements having different energy application conditions that change the physical properties that govern the transfer characteristics are mixed with a solvent such as ethyl methyl ketone or ethylene glycol near-set at a predetermined different mixing ratio. After thorough mixing in the solvent, solvent coating is applied onto a film of polyimide or the like, and the solvent is removed by further drying at 80 ° C. for 3 minutes to obtain the desired recording medium. .

The above example shows the case where the melting temperature and the like of the portion to which a plurality of types of energy are applied becomes high, but as a transfer recording medium, a functional component that softens by receiving a plurality of types of energy or has a low melting temperature and the like is used. When used, the energized portion forms a transfer image. Such sensitive components include polymethyl vinyl ketone, polyvinyl phenyl ketone, copolymers of methyl vinyl ketone and methyl isopropenyl ketone with ethylene and styrene, copolymers of ethylene and carbon monoxide, vinyl chloride, Examples thereof include copolymers of acrylate and carbon monoxide, polyvinyl phenyl ketone, polyamide-imide, polyamide-polysulfone and the like.

Next, an example of the image forming process in the image forming method of the present invention will be described with reference to FIGS. 3 and 4.

FIG. 3 is a schematic view showing an example of an apparatus for carrying out the halftone image forming method of the present invention. This device selectively drives (modulates) a single heating means having a plurality of heating elements in accordance with an image signal, and also, at the position of the driven heating element, the density of an image to be recorded ( Optical density)
To irradiate different wavelengths of light corresponding to the above to form a transfer image in which halftone is expressed,
1 is, for example, two or more kinds of images in which a melting temperature or a softening point is raised by irradiating light such as ultraviolet rays in a state of being melted or softened by heating under a predetermined condition, and the irradiation condition of the light is different. An ink donor film (IDF), which is a transfer recording medium capable of halftone recording, in which a transfer recording layer 1a in which the formed elements are mixed in a predetermined different mixing ratio is provided on a film 1b. . As this IDF 1, in this example, the IDF 1 of the type described in FIGS. 2a to 2d, which has the transfer recording layer having the above-described structure a, was used.

2 is a supply roll around which the IDF 1 is wound, 3 is a light irradiation means such as a low pressure mercury lamp, a high pressure mercury lamp, a metal halide, a fluorescent lamp, a xenon lamp for uniformly irradiating the IDF 1 with light, and 4 is controlled based on an image signal A heating means such as a thermal head that generates a heat pulse by the circuit 5. As a heating method, it is also possible to use an energization heat generation type transfer recording medium which energizes the transfer recording medium to generate heat, and in this case, 4 is an energizing head for generating an electric pulse for energization.

The heating means 4 is provided with a plurality of heating elements (for example, the heating element refers to the heating resistor shown in FIG. 2a when the heating means is a thermal head, and refers to the electrode when the heating means 4 is an energizing head). ing. The heating elements may be arranged in one row, arranged in a matrix, or arranged in a plurality of rows. Further, the heating elements include those which are separated from each other and those in which a continuous rod-shaped electric heating material is separated by a plurality of electrodes, and any type thereof may be used.

Reference numerals 8 and 9 denote transfer means, 8 is a heat roll having a heater 7 therein, and 9 is arranged so as to face the heat roll 8, and a transfer medium 10 such as plain paper or an OHP sheet and the IDF 1 are provided.
A pinch roller that presses between and, 11 is ID after transfer recording
It is a winding roll that winds up F. The recorded image 12 is transferred onto the transfer medium 10 and separated from the IDF.

A thermal pulse based on an image signal is applied to the IDF 1 sent from the supply roll 2 by the thermal head 4. A thermal pulse is applied to the IDF 1 by the thermal head 4, and at the same time, lights having different wavelengths are sequentially emitted from the lamp 3 in synchronization with the thermal pulse based on the image signal. The principle of the transfer image forming process is as described in FIGS. 2a to 2c. The lamp 3 shown in the figure is a schematic one, and it is preferable that a plurality of lamps emit light having different wavelengths.

A transfer image is formed on the transfer recording layer 1a by the thermal head 4 and the lamp 3, and the transfer image is transferred to the transfer medium 10 by the heat roll 8 and the pinch roller 9.

In this case, it is basically one of the selective heating means such as a thermal head that is controlled based on the image signal as described above, and the control circuit can therefore be simplified.
As a result, a compact and highly reliable device can be realized, and stable image formation can be easily performed.

It is also possible to control (modulate) both heating and light irradiation according to the image signal. For example, heat from Figure 2a
Simultaneously with the addition as in the example shown in FIG. 2c, light is irradiated to the position corresponding to the heating resistor that has generated heat. That is, 2a
In the example shown in FIG. 2 to FIG. 2d, the light is uniformly irradiated, but when controlling both heating and light irradiation, the light irradiation position is controlled so as to coincide with the heat generation position of the thermal head. Thus, when the wavelength-dependent one is used as the image forming element, the wavelength of the light to be radiated is sequentially changed to the wavelength set corresponding to the predetermined mixing ratio of each image forming element. When the temperature-dependent one is used as the image forming element, the heating temperature is sequentially changed to the heating temperature set corresponding to the predetermined mixing ratio of each image forming element.

When both heating and light irradiation are controlled (modulated) as described above, it is advantageous to increase the contrast of changes in the physical properties of the transferred image, and a sharp image can be easily obtained. In addition, since the influence on the image when one of them is deteriorated is halved, it is easy to obtain a highly reliable device.

The image forming apparatus according to the method of the present invention may be provided with a plurality of steps for forming a transfer image, which is a particularly advantageous method for increasing the recording speed. In particular, when a heating means such as a thermal head that is driven according to an image signal is used, it is necessary to repeat heating and cooling of the image forming element at high speed in order to perform high speed image formation.

For example, when an image is formed using the transfer recording medium described above with reference to FIGS. 2a to 2d, the time required for heating and cooling the image forming element is set to 4 msec, and the transfer image forming step is performed. One heating / cooling is performed under different energy application conditions (wavelength dependence) for image forming elements 1aa-1 to 1aa-3
If processing is performed for each of the three processes shown in FIGS. 2a to 2d before processing each one of the above, a minimum of 4 msec × 3 = 12 msec is required to process one scan line. on the other hand,
There are three transfer image formation steps and they are far enough apart that there is no thermal effect and they process the imaging element 1aa-1, 1aa-2 or 1aa-3 corresponding to the above example. If the roles are shared, the processing for one scanning line is performed in parallel, which is possible in 4 msec. In this way, a high-speed recording apparatus that can easily perform high-speed processing and can express halftone can be obtained.

FIG. 4 is a schematic view of an apparatus for carrying out another aspect of the image forming method of the present invention. In the example shown in FIG. 4, light irradiation is controlled based on an image signal, and heat is uniformly applied.
That is, in the example shown in FIGS. 2a to 2d, instead of heating the heating resistors 20b, 20c, 20f and 20g, the entire thermal head 20 is uniformly heated to generate the heating resistor 20b. , 20c, 20f and 20g at wavelengths λ ₁
Irradiate the light of. Also when irradiating with light of wavelength λ ₂ , light is irradiated onto the positions corresponding to the heating resistors 20a, 20e, 20f and 20g. Hereinafter, the same applies to the case of irradiating the light of wavelength λ ₃ .

Accordingly, 14 may be a heater for uniformly heating the IDF 1, such as a heat roller like 8 or a heater having ceramics on a ceramic base material. Of course, a temperature sensor and a feedback heater control circuit may be provided for the purpose of highly accurate control of the heating temperature. On the other hand, 15 is a lamp array that is irradiated with light by a control circuit based on an image signal, and is selected according to the spectral sensitivity of the transfer recording layer 1a. , Laser arrays, liquid crystal shutter arrays, etc. A laser scanning system may be used instead of the lamp array.
Further, in the case of having sensitivity in the ultraviolet region, an ultraviolet lamp array or a method of scanning an ultraviolet ray with an optical system is used. In this case, it is easy to obtain high speed and high image quality because the light controlled basically on the basis of the image signal is light with excellent responsiveness and which can reduce diffusivity.

In addition, in the process mode shown in FIGS. 3 to 4, it is also possible to carry out light irradiation after heating and, conversely, heat after light irradiation. The heating and light irradiation surface may be in the same direction or may be opposite to the illustrated one.

Further, in addition to a pigment and a dye as a coloring component, a color former or a color developer that develops a color former may be used so that the image forming element exhibits a color tone. This color development reaction may be performed in the transfer image forming step, or may be performed in the transfer step or thereafter. Further, the recording medium to be transferred may contain, for example, a color developer so that the color is developed by the reaction with the transferred color developer. Examples of such color formers include leuco dyes and diazo groups.

On the other hand, in the case of containing a coloring component such as a pigment or dye that does not use a color-forming reaction, a high-quality halftone with high reproducibility, which is excellent in preservability of a medium before recording and image storability after recording, is generally used. It is easy to get a rendered image.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples and Examples.

Reference Example 1 Image-forming element body composed of the components shown in Tables 1 to 4
1aa-1 to 1aa-4 (particle size; 8 to 12 μm) in polymethylmethacrylate (PMMA), each containing 1aa-1: 1aa-2: 1a
a-3: 1aa-4 = 1: 2: 4: 8 (weight ratio), and dispersed on a base material 1b made of polyimide having a thickness of 6 μm to give a dry film thickness of about 10 to 14 μm. Thus coated and dried to obtain a transfer recording layer 1a shown in FIG. The image forming elements 1aa-1 to 1aa-4 are formed so that the individual optical densities of the image forming elements 1aa-1 to 1aa-4 are substantially equal to each other.

The sensitizers or photoinitiators in the image forming elements shown in Tables 1 to 4 are about 450 to 600 nm, about 380 to 450 nm, and about 340, respectively.
It absorbs light in the band of ~ 380 nm and about 280-340 nm and starts the reaction.

In addition, since the sensitizer contained in the image forming element 1aa-1 having the composition shown in Table 1 has a magenta taste, a black color is obtained when the image forming element is transferred to the transfer medium. As shown in the table, phthalocyanine green is further added as a coloring agent, and the image forming element 1aa of the composition shown in Table 2 is added.
In -2, benzoin contained as a sensitizer has a yellowish tint, and therefore phthalocyanine blue is further added as a colorant so that the image-forming element exhibits black when transferred to a transfer medium. There is.

The transfer recording medium 1 thus created was wound into a roll and incorporated into the apparatus as a supply roll 2.

As shown in FIG. 5, the thermal recording head 4 of the transfer recording medium is used by using a thermal head 4 which is a line type of A4 horizontal size of 8 dots / mm and in which heating resistors (heating elements) are arranged in a line at the edge portion. The material 1b side was arranged so as to be in contact with the heating resistor, and was pressed by the heating resistor by the tension of the transfer recording medium 1.

On the other hand, in the portion of the thermal head 4 facing the heat-generating resistor, four types of light sources 3a to 3d each having the spectral characteristic shown in FIG. 6 were placed 2 cm apart from the transfer recording medium.

Light source 3a is (La, Ce, Tb) ₂ O ₃ · 0.2SiO ₂ · 0.9P activated by Tb ³⁺
_{It is} a 40w high color rendering green fluorescent lamp using ₂ O ₅ as a phosphor, and irradiates the light having the spectral characteristic shown by a in FIG. 6 to process the image forming element body 1aa-1. The light source 3b is Eu as a phosphor.
⁺⁺ A 60w fluorescent lamp for a diazo copier that uses activated (SrMg) ₂ P ₂ O _{7 and} has a sharp cut filter L-38 (manufactured by Hoya Glass Co., Ltd.) shown in FIG. The image forming element body 1aa-2 is processed by irradiating light having the spectral characteristic shown in FIG. 6B through the filter provided. The light source 3c is a 60w black light 3c (trade name, made by Toshiba), and a sharp cut filter L-1A (made by Hoya Glass Co., Ltd.) shown at 19 in FIG. 5 is provided on the front surface thereof. The image forming element body 1aa-3 is processed by irradiating the light having the spectral characteristic shown by c in FIG. 6 through the filter. Further, the light source 3d is a 40w health ray lamp (trade name, manufactured by Toshiba), and irradiates light having the spectral characteristic shown by d in FIG. 6 to process the image forming element 1aa-4.

In this reference example, the thermal head 4 is controlled so that the image forming element is not energized when the image forming element is transferred to the heating resistor, and is energized to generate heat when the image forming element is not transferred. When this heat is generated, the energizing energy is 0.8w / dot × 2.0msec.

First, in order to form the non-recorded portion, all the heating resistors are energized, and the light sources 3a to 3d are sequentially placed at intervals of 1 msec for 4 msec.
And transfer all the image forming elements of the transfer recording layer 1a to a state in which they are not transferred, and then the transfer target medium 1 is heated by a stepping motor (not shown) and a heat roll 8 and conveyed by the amount of light irradiation processing. To move forward, and perform the same process again. Further, this operation was repeated to form a non-recorded portion (No. 1 in Table 5) on which the image forming element was not transferred.

Next, all the heating resistors are energized, and the light sources 3b, 3c, and 3d are sequentially irradiated at intervals of 1 msec for 4 msec each, and the image forming element 1aa-
After changing all of 2, 1aa-3, and 1aa-4 to the non-transferred state, the transferred medium 1 is conveyed by a stepping motor (not shown) and a heat roll 8 and the same process is performed again. The image forming element 1aa-1 corresponds to a solid printing portion (No. 2 in Table 5), that is, 1 of the whole image forming element 1a-1 according to the mixing ratio of the image forming element 1aa-1. A transfer image consisting of / 15 was formed.

Further, all the heating resistors are energized, and the light sources 3a, 3c, and 3d are sequentially irradiated at intervals of 1 msec for 4 msec each to form an image forming element body.
After changing all of 1aa-1, 1aa-3, and 1aa-4 to the non-transferred state, the transferred medium 1 is conveyed by a stepping motor (not shown) and a heat roll 8 and the same process is performed again. By repeating this operation, the image forming element 1aa
Corresponding to the solid print section consisting of -2 (No. 3 in Table 5),
That is, a transfer image composed of 2/15 of the entire image forming element was formed according to the mixing ratio of the image forming element 1aa-2.

Hereinafter, except that the respective light sources 3a to 3d are combined and irradiated as shown in Table 5, the solid printing section No. 4 including the combination of the image forming elements as shown in Table 5 is similarly used. ~ 16
And a transfer image corresponding to the above was formed.

The portion of the transfer recording medium where the transferred image is formed has a heater 7 of 300w inside, a heat roll 8 made of an aluminum roll coated with 2 mm thick silicone rubber, and a pinch roll 9 which is a silicone rubber roll having a hardness of 50 °. Transported by
The plain paper 10 having a surface smoothness of 10 to 30 seconds and the transferred image surface are overlapped with each other, and heated to 90 to 100 ° C. by the heat roll 8, the plain paper 10 is pinched by the pinch roll 9 to 1 to 1.5 kg / cm ²
The transfer image of that portion was transferred to plain paper, and solid print portions No. 2 to 16 composed of a combination of image forming elements as shown in Table 5 were sequentially formed.

The optical density of a minute portion corresponding to the heat-generating resistor of the thermal head in the obtained solid print portion was measured using a microdensid photometer, and the results are shown in Table 5.

As shown in Table 5, in this reference example, 16 kinds of optical density gradations (0.06 to 1.20) could be expressed including the part in the non-recorded state.

Example 1 Using the recording apparatus and the transfer recording medium used in Reference Example 1, an image in which halftone was expressed was formed as follows.

In the case of the present embodiment, since the transfer recording layer 1a whose light and heat are applied to raise the glass transition point is used, negative recording is performed. In this embodiment, the control of the thermal head 4 does not energize when there is a mark signal (printing is done), and energizes to generate heat when there is no mark signal (printing does not occur). When this heat is generated, the energizing energy is 0.8w / dot × 2.0msec.

FIG. 7 shows a drive timing chart of the apparatus in the transfer image forming process in this embodiment.

The image signal input to the apparatus is an image to be recorded (original image) based on the relationship between the combination of the image forming elements obtained in Reference Example 1 and the optical density of the recorded image. Is obtained by analyzing. Therefore, in the present embodiment, the recorded image is represented by 16 density gradations.

First, at the start of transfer image formation, the image forming element 1aa-1
Based on the image signal according to the mixture ratio of, the heating resistor corresponding to the mark signal is not energized, and the heating resistor not corresponding to the mark signal is energized for 2 msec to generate heat and at the same time the light source 3a is turned on. , The state where the light is uniformly radiated for 4 msec and one of the image forming elements 1aa-1 on one line 1 of the thermal head, which is on the heating resistor which is generating heat, is not transferred in the subsequent transfer process. Change to.

When 1 msec has elapsed after the irradiation with the light source 3a is completed, the process for the image forming element body 1aa-2 is started next.

That is, based on the image signal according to the mixture ratio of the image forming element 1aa-2, the heating resistor corresponding to the mark signal is not energized, and the heating resistor not corresponding to the mark signal is 2 msec.
The light source 3b is turned on at the same time to turn on the heat to irradiate the light for 4 msec, and the light is evenly emitted for 4 msec. The image forming element 1aa-2 on one line of the thermal head is on the heat generating heating element. Change things into a non-transferred state.

Thereafter, the image forming elements 1aa-3 and 1aa-4 are similarly processed at intervals of 1 msec after the irradiation of the light source 3b according to the drive timing chart shown in FIG. (Latent image) is formed, and the above operations are repeated in accordance with the image signal to complete the formation of all transfer images.

The transfer image formed on the transfer recording medium is conveyed by the heat roll 8 and the pinch roll 9 in synchronism with the repeating cycle of 20 msec / line of the drive chart shown in FIG.
By the same operation as above, the images were sequentially transferred onto plain paper 10 having a surface smoothness of 10 to 30 seconds.

The image obtained in this example was clear, had a good fixing property, and was a high-quality image in which the halftone was reproduced faithfully to the shading of the original image.

Reference Example 2 Imaging element bodies 1aa-5 and 1aa-6 (particle size; 8 to 12 μm) composed of the components shown in Tables 6 and 7 were added to 1aa-5: 1aa-5 in polymethylmethacrylate (PMMA). Dispersed so that 1aa-6 = 1: 3, this was applied on a base material 1b made of polyimide having a thickness of 6 μm so that the dry film thickness was 2 to 3 μm, and dried to obtain a transfer recording layer 1a. . The image forming element
1aa-5 and 1aa-6 are formed such that their individual optical densities are substantially equal to each other.

The sensitizer in the image forming element 1aa-5 having the composition shown in Table 6 absorbs light in the band of about 350 to 440 nm and starts the reaction. Further, since this sensitizer has a yellowish tint, the image forming element further contains dark blue as a coloring agent so that it exhibits black when transferred to the transfer medium.

On the other hand, the sensitizer in the image forming element 1aa-6 having the composition shown in Table 7 absorbs light in the band of about 500 to 600 nm and starts the reaction. Further, since this sensitizer has a magenta taste, this image-forming element further contains phthalocyanine green as a coloring agent so that it exhibits black when transferred to the transfer medium.

The transfer recording medium obtained as described above was set in an apparatus as shown in FIG.

The heating means for the transfer recording medium in this apparatus is a heater 14 that uniformly heats the A4 lateral size from the side of the base material 1b of the transfer recording medium 1. , A liquid crystal shutter array 21 having an A4 lateral size and a plurality of shutters 23 arranged in two rows as shown in FIG.
Is provided. The aperture size of each shutter 23 is 0.4 × 0.4 mm, and the arrangement pitch is vertical and horizontal.
It is 0.5 mm. Also, the shutter array 2 shown in FIG.
Each shutter 23 of the shutter array 21a on the front side in the traveling direction of the transfer recording medium 1 of 1 is provided with a blue filter (trade name; Fuji Filter SP 1, manufactured by Fuji Photo Film Co., Ltd.) that passes a large amount of light of 500 nm or less. , And shutter array
Each shutter 23b of 21b is provided with a yellow filter (trade name: Fuji Filter SC 50, manufactured by Fuji Photo Film Co., Ltd.) that transmits a large amount of light of 500 nm or more. Furthermore, a 2 kw xenon lamp is installed above the shutter array 21, and a light shield (not shown) is used so that the light emitted from this will pass only through the shutter array, that is, not to irradiate the transfer recording medium. It is shielded from light.

Using the apparatus having the above-mentioned configuration, four types of solid printing portions formed by combining the image forming elements shown in Table 8 were formed as follows.

First, with the light source 20 turned on, the heater 14 heats a portion of the transfer recording medium corresponding to the heater to 95 ° C., and simultaneously opens each shutter 23 of the shutter array 21a for 28 msec. Is irradiated with light that has passed through the blue filter, and the portion of the image-forming element 1aa-5 that has been irradiated with light is changed to a state where it is not transferred in the subsequent transfer step.

Next, all shutters are closed for 12 msec, and during that time, the transfer recording medium 1 is advanced by the width processed under the shutter array 21a by being conveyed by a stepping motor (not shown) and a heat roll 8. Then, the portion of the transfer recording medium processed under the shutter array 21a is the shutter array 21.
b under the shutter array 21a, transfer recording layer
The unprocessed part of 1a moves.

Here, all the shutters of the shutter arrays 21a and 21b are opened for 28 msec and light is emitted. By this irradiation processing, the shutter array 2 already under the shutter array 21b is
The part that was processed with the light of the blue filter under 1a is further processed with the light of the yellow filter, and the image forming element of this part
1aa-6 also reacts, and as a result, all the image-forming elements in this portion are not transferred in the subsequent transfer step. At the same time, under the shutter array 21a, the operation of processing the image forming element body 1aa-5 performed first is repeated. Further, by repeating the above operation, the non-recorded area (8th
A portion corresponding to No. 17) in the table was formed on the transfer recording layer 1a.

Next, the unprocessed portion of the transfer recording medium that has moved to below the shutter array 21a is passed through the shutter array 21a without being irradiated by the shutter array 21a, that is, without performing the irradiation processing by the blue filter. When moving to the lower side of 21b, all the shutters of the shutter array 21b are opened for 28 msec to irradiate light passing through the yellow filter, and the image forming element of this part
Only 1aa-6 is allowed to react, leaving it untranscribed. Further, by repeating the above operation, the image forming element body 1aa-5
A transfer image corresponding to the solid printing portion No. 18 formed from only the image forming element body 1aa-5 was formed on the transfer recording layer 1a by 1/4 of the whole image forming element body according to the mixing ratio of the image forming element body 1aa-5. .

Further, the unprocessed part of the transfer recording medium 1 which has moved to the lower part of the shutter array 21a is irradiated with a blue filter by opening all the shutters of the shutter array 21a for 28 msec, and only the image forming element 1aa-5 of this part is processed. When the area is moved below the shutter array 21b by reacting it so that it is not transferred, all the shutters of the shutter array 21b are kept closed, that is, they are passed through without being irradiated by the yellow filter. The image forming element 1a is repeated by repeating the above operation.
Corresponding to the solid printing section No. 19 formed only from a-6,
That is, a transfer image composed of 3/4 of the whole image forming element 1a-6 was formed on the transfer recording layer 1a according to the mixing ratio of the image forming element 1aa-6.

Finally, without performing light irradiation processing under the shutter arrays 21a and 21b, that is, all of the image forming element of the transfer recording layer 1a is passed under the shutter array 21 as a state to be transferred in a later transfer step, Imaging element bodies 1aa-5 and 1aa
A transfer image corresponding to the solid printing portion No. 20 formed from No. 6, that is, a transfer image formed from all the image forming elements 1aa-5 and 1aa-6 was formed on the transfer recording layer 1a.

The portion of the transfer recording medium where the transferred image is formed has a heater 7 of 300w inside, a heat roll 8 made of an aluminum roll coated with 2 mm thick silicone rubber, and a pinch roll 9 which is a silicone rubber roll having a hardness of 50 °. Transported by
1 to 1.5 kg / cm ^{2 of} plain paper 10 by pinch roll 9 while being superposed on plain paper 10 having a surface smoothness of 10 to 30 seconds from the transfer image side and heated to 90 to 100 ° C. by heat roll 8.
Then, the transferred images in that portion were sequentially transferred to plain paper, and solid print portions No. 18 to 20 composed of a combination of image forming elements as shown in Table 8 were formed.

Each shutter of the shutter array of the obtained solid printing part
The optical density of the portion corresponding to the size of 23 was measured using a microdensid photometer, and the results are shown in Table 8.

As shown in Table 8, in this reference example, it was possible to express four kinds of optical density gradations (0.06 to 1.20) including the non-recorded state portion.

Example 2 Using the recording apparatus and the transfer recording medium used in Reference Example 2, an image expressing halftone was formed as follows.

In the case of the present embodiment, since the transfer recording portion 1a in which light and heat are applied to raise the glass transition point is used, negative recording is performed.

The image signal input to the apparatus is based on the relationship between the combination of the image forming elements obtained in Reference Example 2 and the optical density of the image to be recorded (the original image). ) Is obtained. Therefore, in the present embodiment, the recorded image is represented by four density gradations.

In this embodiment, the image signal of one line is divided into a signal for processing the image forming element body 1aa-5 and a signal for processing the image forming element body 1aa-6, and these are divided by the shutter array with a time difference of 40 msec. Filled in 21a and 21b in this order.

That is, with the light source 20 turned on, the heater 14 heats the portion of the transfer recording medium in contact with the heater to 95 ° C., and at the same time, processes the image forming element 1aa-5 of the image signal L _1. A predetermined shutter of the shutters 23 of the shutter array 21a is opened for 28 msec according to the signal to irradiate the transfer recording medium 1 with light, and the portion of the image forming element 1aa-5 where the light is irradiated is not transferred in the subsequent transfer step. Changed to the state.

Next, all shutters are closed for 12 msec, and during that time, the transfer recording medium 1 is advanced by the width processed under the shutter array 21a by being conveyed by a stepping motor (not shown) and a heat roll 8. Then, the portion of the transfer recording medium processed under the shutter array 21a is the shutter array 21.
It moves to the bottom of b, and the unprocessed part moves to the bottom of the shutter array 21a.

Here, a predetermined shutter of the shutter array 21b is opened for 28 msec according to a signal for processing the image forming element body 1aa-6 of the image signal L ₁ , and the transfer recording medium 1 is irradiated with light, and the portion irradiated with the light is irradiated. The image forming element 1aa-6 is changed to a state in which it is not transferred in the subsequent transfer step. Then, a latent image (transfer image) according to the image signal L ₁ was formed in this portion.

On the other hand, at the same time as the processing under the shutter array 21b,
Under shutter array 21a, for the second row of the formation of the image, processing in accordance with the signal for treating the imaging element 1aa-5 of Eshingo L ₂ is performed. Further, the above-described operation was repeated according to the image signal, and transferred images were sequentially formed.

The transfer recording medium on which the transfer image is formed has the light irradiation timing as described above, that is, 28 msec with an interval of 12 msec.
The transfer recording medium is conveyed by the heat roll 8 and the pinch roll 9 in synchronism with the repetition cycle of 40 msec, which is the irradiation of the image.
It was sequentially transferred to plain paper 10 for 10 to 30 seconds.

The image obtained in this example was clear, had a good fixing property, and was a high-quality image in which the halftone was reproduced faithfully to the shading of the original image.

〔The invention's effect〕

As described above, in the present invention, the transfer recording medium whose properties change rapidly when a plurality of types of energy are simultaneously applied is used, so that the heat affected by the environmental temperature as in the conventional method is used. Compared with the method using only the recording medium or the method using the transfer recording medium that changes the characteristics only by the light energy, the environmental stability is higher, and it is possible to always obtain a stable and highly accurate image. Further, for this reason, the preservability of the transfer recording medium and the preservability of the recorded image are improved.

Further, for example, in the method using only heat, the recording speed is governed by the thermal responsiveness of the system, and it takes a long time to give the energy necessary for image formation to the transfer recording medium with only one energy. On the other hand, the present invention is suitable for high speed recording because it is controlled by two or more energies.

Further, in the present invention, a transfer image can be formed by continuously irradiating light having different wavelengths in a short time, and the transfer number of the image forming element exhibiting the same optical density or different optical numbers can be obtained. Directly controlling the amount of a coloring component forming a recorded image by transferring to a transfer target material while controlling the combination of two or more kinds of image forming elements exhibiting density and the transfer number thereof according to the recording information. The density gradation can be expressed by changing the optical density of one recording pixel as desired, and the conventional area gradation method using the matrix composed of a plurality of pixels to express halftone is used. It is possible to form a high-quality image in which halftone is well expressed in a short time without lowering the resolution as in the thermal transfer recording method.

Further, since the step of forming the transfer image and the step of transferring the transfer image are independent, conditions suitable for transferring the transfer image to the transfer medium with high quality and stably are independent of the conditions for forming the transfer image. It can be set freely. Therefore, it is possible to obtain a high-quality image by using not only plain paper but also paper having low surface smoothness or a wide range of transfer media such as transparency as the transfer medium. At the same time, excellent fixability can be obtained.

[Brief description of drawings]

FIGS. 1a to 1d are graphs for explaining the principle of forming a transfer image by light and thermal energy.
FIGS. 2 to 2d are schematic views showing the relationship between the transfer recording medium, the thermal head and the light irradiation in the transfer image forming step in the present invention, and FIG. 3, FIG. 4, FIG. 5 and FIG. Are schematic views of the apparatus used in the image forming method of the present invention, FIG. 6 is a graph showing the spectral characteristics of the light source used in the apparatus shown in FIG. 5, and FIG. FIG. 9 is a drive timing chart of the apparatus shown in the figure, and FIG. 9 is a plan partial view of a liquid crystal shutter array used in the apparatus shown in FIG. 1: Transfer recording medium, 1a: Transfer recording layer 1aa: Image forming element, 1b: Substrate 2: Supply roll, 3: Lamp 3a: High color rendering green fluorescent lamp 3b: Diazo copying machine fluorescent lamp 3c: Black light, 3d: Health line lamp 4: Thermal head, 5: Control circuit 7: Heater, 8: Heat roller 9: Pinch roller, 10: Recording paper 11: Take-up roll, 12: Recorded image 14: Heater, 15: Lamp array 16, 17: Lighting control circuit 18: Sharp cut filter L-38 19: Sharp cut filter L-1A 20: White light source 21: Liquid crystal shutter array 21a: Shutter array 21b: Shutter array 22: Shield control circuit, 23: Shutter 24a: Blue Filter 24b: Yellow filter

Claims (17)

[Claims] 1. A transfer recording medium having a transfer recording layer in which two or more kinds of image forming elements having different energy application conditions for changing the physical properties governing the transfer characteristics are mixed at a predetermined different mixing ratio. A step of forming a transfer image on a transfer recording medium by applying two or more kinds of energy under conditions corresponding to the optical density exhibited by the image forming element according to the record information, and transferring the transfer image to the transfer medium. A halftone image forming method. 2. The halftone image forming method according to claim 1, wherein each of the image forming elements exhibits the same optical density. 3. The halftone image forming method according to claim 1, wherein each of the image forming elements exhibits a different optical density depending on an energy application condition that changes a physical property that governs a transfer characteristic of the image forming element. 4. The halftone image formation according to claim 1, wherein two or more kinds of image forming elements having the same energy application conditions for changing the physical properties that govern the transfer characteristics exhibit different optical densities. Method. 5. The energy applied to the transfer recording medium to form a transfer image is two or more kinds selected from the group consisting of heat, light and pressure. The halftone image forming method according to any one of 1. 6. The halftone image forming method according to any one of claims 1 to 4, wherein the energy applied to the transfer recording medium to form a transfer image is heat and light. 7. The halftone image forming method according to claim 6, wherein the different energy application conditions for each of the two or more types of image forming elements are different wavelengths of light energy. 8. The method according to claim 7, wherein the thermal energy modulated according to the recorded information is applied together with the optical energy of the wavelength selected according to the type of the image forming element whose physical properties governing the transfer characteristics are desired to be changed. The halftone image forming method described. 9. The intermediate according to claim 7, wherein light energy having a wavelength which is modulated according to recording information and which is selected according to the kind of image forming element whose transfer characteristics are desired to be changed is applied together with heat energy. Toning image forming method. 10. The halftone image forming method according to claim 9, wherein the thermal energy is also modulated according to the recorded information. 11. The halftone image forming method according to claim 6, wherein the energy application condition different for each of the two or more image forming elements is a temperature at which the thermal energy is different. 12. A single heating means provided with a plurality of heating elements is selectively driven according to recording information, and at least the position of the driven heating element is adjusted to the optical density of an image to be recorded. 7. The halftone image forming method according to claim 6, which irradiates light of different wavelengths to form an image in which halftone is expressed. 13. A transfer recording layer in which two or more kinds of image forming elements having different energy applying conditions for changing the physical properties that govern the transfer characteristics are mixed in a predetermined different mixing ratio. Transfer recording medium. 14. The transfer recording medium according to claim 13, wherein each of the image forming elements exhibits the same optical density. 15. The transfer recording medium according to claim 13, wherein each of the image forming elements exhibits a different optical density depending on an energy application condition that changes a physical property that governs a transfer characteristic of the image forming element. 16. Two of the image forming elements having the same energy application condition for changing the physical properties that govern the transfer characteristics.
14. The transfer recording medium according to claim 13, wherein one or more kinds exhibit different optical densities. 17. The energy for changing the physical properties governing the transfer characteristics of the image forming element is two or more kinds selected from the group consisting of heat, light and pressure. Item 17. The transfer recording medium according to any one of items 16.