JPH074941B2 - Halftone image forming method - Google Patents

Description

The present invention relates to a halftone image forming method that can be used in a copying machine, various printers, and the like.

[Conventional technology]

In recent years, 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. One of such recording methods is a heat-sensitive recording method. This method is widely used in recent years because the apparatus used is lightweight and compact, has no noise, and has excellent operability and maintainability.

Among these heat-sensitive recording methods, the heat-sensitive transfer recording method has recently attracted particular attention. This method of recording is generally
A heat-sensitive transfer medium obtained by applying a heat-transferable ink having a colorant dispersed in a heat-meltable binder on a sheet-shaped support is used, and the heat-sensitive transfer medium is used as a transfer medium. The transfer recording image according to the heat supply pattern is superimposed on the transfer medium so that they are in contact with each other, and heat is supplied from the support side of the thermal transfer medium by a thermal head or the like to transfer the melted ink layer to the transfer medium. It is formed on the transfer medium. According to this method, plain paper can be used as the transfer medium.

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. 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 to prevent a thermal stroke between the heat generating segments forming the thermal head surface. Theoretically, it was difficult to increase the amount of heat supplied from the thermal head. Therefore, high-speed recording has been difficult with the conventional thermal recording method.

In addition, since heat conduction has a slower response response than electricity or light, it is generally difficult to control the heat pulse until halftone can be reproduced when recording with a thermal head. Since the heat-sensitive transfer ink layer of No. 1 does not have transfer characteristics capable of expressing gradation, it was not possible to form a halftone recorded image for each pixel.

[Problems to be solved by the invention]

The present invention is an image forming method that solves the problems of the above-mentioned conventional thermal transfer recording method, that is, it is possible to form a high-quality transfer image on the most commonly used plain paper having a low surface smoothness, Another object of the present invention is to provide an image forming method capable of high-speed recording and capable of forming a halftone recorded image.

[Means for solving problems]

That is, the image forming method of the present invention changes the physical properties that control the transfer characteristics by applying a plurality of types of energy, and corresponds to the magnitude of the energy of at least one of the plurality of types of energy. A transfer recording medium having an image forming element in which the degree of change in physical properties that governs the transfer characteristic is changed in a transfer recording layer, and at least one kind of energy of the plurality of kinds of energy is recorded in the halftone recording information. And a step of forming a transfer image on the transfer recording layer by applying the plurality of kinds of energy while changing the conditions under the conditions, and a step of transferring the transfer image to a transfer medium.

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. Further, the transfer image formed in the transfer image forming step is
This image is formed by changing the physical properties that govern the transfer characteristics of the image-forming element in the transfer layer, rather than a mere property change image such as a heat-melt image. Therefore, this changed physical property difference is used in the transfer process. As a result, the transfer can be surely realized, and the transfer image can be faithfully transferred. For example, when a thermal fusion image is used as a transfer image, it is necessary to completely maintain the thermal fusion image from the transfer image forming step to the transfer step. Image blurring due to heat conduction to the periphery of the fusion image is inevitable. However,
In the case of the present invention, the transfer image is formed by changing the physical properties that govern the transfer characteristics, such as the melting point, softening point, viscosity at the same temperature, etc. of the image-forming element in the transfer recording layer.
This change in physical properties is stored up to the transfer step. Therefore, unless the energy for changing the physical properties is applied after the transfer image forming step, the transferability of the transfer image is not deteriorated and image blurring does not occur. Therefore, even when the surface smoothness of the transfer medium is low, it is possible to form a halftone image with high image quality, and the transfer image can be transferred to the transfer medium without degrading the image quality.

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 to the case where the signalized energy for is used as the energy for transfer at the same time,
The constraint conditions for energy application are greatly relaxed. For example, the energy for transfer image formation may be an amount enough to cause a change in the physical properties of the image forming element, and the energy for transfer may be a non-signaled uniform energy. The transfer speed can be increased according to the transfer speed, and high-speed recording can be easily realized.

In the thermal head used in the conventional thermal transfer recording apparatus, even 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 maximum personnel for preventing 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, the transfer characteristics will be controlled 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.

In addition, the halftone image forming method according to the present invention forms a transfer image by applying plural kinds of energy.
Compared to the conventional method of forming a transfer image only by heat, the degree of change in the physical properties of the transfer image can be adjusted in stages, and the response response is quick and strong as one of multiple types of energy. The use of light that is easy to adjust stepwise facilitates the formation of an image that requires a halftone representation. For example, set the intensity or time of three stages of light irradiation,
When combined with heating, gradation expression of 4 steps (3 steps + non-heating) becomes possible.

Further, although it is desired that such control be performed at high speed, the fact that energy with a fast response response such as light can be used is also one factor that enables high-speed halftone recording. Of course, gradation expression is possible by dividing the heating time and heating temperature into a plurality of steps.

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, and this physical property is arbitrarily changed depending on the type of the image forming element used. For example, in the case of a transfer recording medium that transfers a transferred image in a heat-melted state,
It is a melting temperature, a softening temperature, a glass transition point, or the like, and is a viscosity at the same temperature in the case of a transfer recording medium in which a transfer image is transferred in an adhesive state or a penetrating state to a transfer medium.

Further, a plurality of types of energy used for forming a transfer image are also arbitrarily determined depending on the type of transfer recording medium to be used, and for example, light, electron beam, heat, pressure and the like are appropriately combined and used.

Next, for explaining the principle of the halftone image forming method of the present invention,
A halftone image forming method in which a transfer image is formed by applying light and heat energy will be described with reference to FIGS. 1a to 1f.

The time axes (horizontal axes) of the graphs in FIGS. 1a to 1d correspond to each other. Further, the image-forming element constituting the transfer recording layer contains, as a sensitive component, a polymerizing component containing a reaction initiator and a crosslinking agent 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 time 0 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 then the temperature decreases thereafter. The image forming element in this transfer recording layer has a glass transition point Tg ₀ , and is rapidly softened and its viscosity is reduced in a temperature range of Tg ₀ or higher. This state 1c
It is shown by curve A in the figure. After reaching Tg ₀ at time t ₂ , the viscosity continues to decrease until time t ₄ when the maximum temperature is reached, and the viscosity increases again with a decrease in temperature, and the viscosity sharply increases until time t ₆ when it decreases to Tg _0. . In this case, the physical properties of the image forming element are basically unchanged from those before heating, and when the temperature is raised to the temperature Tg ₀ or higher in the next transfer step, the same phenomenon of change in viscosity as described above is again exhibited. Therefore, if the image forming element is heated by being pressed against the medium to be transferred and heated for transfer, for example, Tg ₀ or more, the image forming element is transferred by a mechanism similar to the transfer mechanism of the conventional thermal transfer recording. However, in the case of the method of the present invention, as shown in FIG. 1d, when the transfer recording layer is heated and irradiated with light at time t _{2, the} reaction initiator contained in the image-forming element is irradiated with light. When activated and the temperature rises sufficiently to increase the reaction rate, the reaction initiator acts to produce an activated crosslinker, which dramatically increases the probability of crosslinking the crosslinkable prepolymer. And the curing of the image forming element progresses.

When the heating and the light irradiation are simultaneously performed in this way, the image forming element behaves as shown by the curve B in FIG. 1c. Then, as the crosslinking reaction proceeds, the glass transition point rises, and at the time t ₅ when the crosslinking ends, as shown in FIG. 1d, Tg ₀ to Tg ₁
Changes to.

The curves C and D show the cases where the light irradiation time was changed between t ₂ and t ₅ . In addition, Fig. 1e shows the viscosity vs. temperature characteristics when these are reheated. That is, the glass transition point of the image-forming element depending on the light irradiation time is Tg ₁ , T
Change to g ₂ or Tg ₃ .

On the other hand, the viscosity of the image-forming element and the optical density of the transferred image in the transfer step have a relationship as shown in FIG. 1f. The lower the viscosity, the higher the transfer efficiency, and the higher the transferred image density.

Further, when the light irradiation time to the image forming element in one pixel is changed, the area occupied in one pixel of the image forming element which changes to Tg ₁ shown in FIG. Gradation recording can also be performed by changing the amount of the image forming element transferred within one pixel.

After the halftone transfer recording image is formed in this way, in the transfer step, for example, the temperature Tr satisfying Tg ₀ , Tg ₂ , Tg ₃ <Tr <Tg ₁
When heated to, the viscosity changes as shown in Figure 1e,
Only the portion whose viscosity has decreased due to heating is transferred onto the transfer medium according to the degree of decrease in viscosity, and images with different optical densities are recorded (gradation recording). Although it depends on the accuracy of temperature stability in the transfer step, Tg ₁ -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.

Although the case where the light irradiation time is changed has been specifically described above, the formation of a similar halftone transfer image by changing the temperature as the energy that changes the characteristics that govern the transfer characteristics of the image forming element, The transfer can be performed. The reaction sensitivity S for a mixture of an acrylic acid ester copolymer as a polymerizable prepolymer, tetraethylene diacrylate as a cross-linking agent, benzophenone as a photoinitiator, and hydroquinone as a stabilizer is represented by the following formula S = A (T-Tg). This is reported in J. Pol. Sci. 20 847-861 (1982).

Therefore, the degree of progress of the crosslinking reaction is changed by changing the temperature, and the molecular weight of the polymer is increased with the progress of the crosslinking reaction, and the temperature characteristic of melt viscosity is changed in the same manner as in FIG. 1e shown above. However, it is possible to form a halftone image.

The halftone transfer recording medium used in the present invention changes the characteristics governing the transfer characteristics when a plurality of types of energy are applied, and corresponds to at least one of the plurality of types of energy. Any structure may be used as long as it has an image forming element in which the degree of change in physical properties that governs the transfer characteristics is changed. As the physical properties that govern the transfer characteristics, for example, the above-mentioned melting temperature is a softening point,
Examples include physical properties such as glass transition point and viscosity. Examples of the image-forming element body in which the degree of change in physical properties that govern the transfer characteristics are changed include an image-forming element body containing a coloring component and a polymer component as a sensitive component. By polymerizing the polymerizing component, the melting temperature and the like of the transfer recording layer at that portion becomes high, and the portion not polymerized forms a transfer image.

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 diacrylate 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 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. Examples of the initiator that acts by light energy as a reaction initiator include benzophenone, benzyl, benzoin ethyl ether, 4-N, N-
Carbonyl compounds such as dimethylamino-4'-methoxy-benzophenone; organic sulfur compounds such as dibutyl sulfide, benzyl disfilled, decyl phenyl sulfide; peroxides such as di-tert-butyl peroxide, benzoyl peroxide; carbon tetrachloride , Halogen compounds such as silver bromide and 2-naphthalenesulfonyl chloride; nitrogen compounds such as azobisisobutyronitrile and benzenediazonium chloride; and the like.

Further, examples of a substance that receives thermal energy and acts as a reaction initiator include, for example, methyl hydroperoxide and t-
Butyl hydroxy peroxide, di-t-butyl hydroperoxide, t-butyl cumyl peroxide, peroxyacetic acid, peroxybenzoic acid, acetyl peroxide, propionyl peroxide, isobutyryl peroxide, acetoperoxide, diazoaminobenzene, methyl ethyl ketone peroxide Examples thereof include oxide, dimethyl-3,2'-azoisobutyrate, diphenyl sulfide, benzoyl disulfide and the like.

In particular, the structure of the transfer recording layer in the case of forming a transfer image by receiving both light and thermal energy, the reaction rate of reaction rate by the reaction between the above-mentioned reaction initiator which acts upon receiving light energy and the polymerizing component. The types of the reaction initiator and the polymerizing component may be selected so that the combination is highly temperature-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, yellow lead, molybdenum red and red iron oxide, Hansa Yellow, Benzidine Yellow, Brilliant Carmine 6B, Lake Red C, Permanent Red F5R, Phthalocyanine Blue, Victoria Blue Lake. , Organic pigments such as Fast Sky Blue, and coloring agents such as leuco dyes and phthalocyanine dyes.

In addition, the image-forming element may contain stabilizers such as hydroquinone, p-methoxyphenol, p-tert-butylicatechol 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 for increasing activation of the reaction initiator against energy are used. It may be contained in the transfer recording layer.

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

Composition of polymerizable prepolymer having functional group, photosensitive cross-linking agent, reaction initiator, sensitizer, stabilizer, colorant, etc. is made into minute image forming element by melt mixing method or spray drying method. . Furthermore, after thoroughly mixing the image-forming element with a binder such as polyester resin in a solvent such as methyl ethyl ketone or ethylene glycol near acetate, solvent coating is performed on a film such as polyimide, and further, for example,
The desired recording medium is obtained by drying at 80 ° C. for 3 minutes to remove the solvent.

As an example of the halftone image forming method of the present invention using such a transfer recording medium, the following embodiments are exemplified.

(1) Both heat energy and light energy are applied to a transfer recording medium while changing at least one of heat energy and light energy under the condition corresponding to halftone recording information, and the melting point, the solution viscosity, etc. are gradually changed. After forming the transfer image composed of the changed parts, the transfer recording medium is heated under conditions such that at least a part of the image forming element whose physical properties governing the transfer characteristics are changed is not transferred, and the transfer medium is transferred. A mode in which a transfer image is transferred to.

(2) A structure in which a reaction initiator that acts by heat and a polymerizing component are mixed at a portion under pressure (for example, the reaction initiator is encapsulated in a capsule, and the capsule is broken by the application of pressure to cause a reaction. (Initiator and polymeric component are mixed)
With respect to the transfer recording medium, while changing at least one of the pressure and the thermal energy under the condition corresponding to the halftone recording information, applying both the pressure and the thermal energy,
A mode in which a transfer image similar to that in the case of the above (1) is formed, and this transfer image is transferred in the same manner as in the above (1).

(3) For a transfer recording medium having a structure in which a reaction initiator that acts only by light energy and a polymerizing component are mixed in a portion under pressure, at least one of pressure and light energy is used as halftone recording information. Applying both pressure and light energy while changing under the corresponding conditions, the above (1)
A mode in which a transfer image similar to that in the case of (1) is formed and this transfer image is transferred in the same manner as in (1).

(4) At least one of pressure, heat, or light energy with respect to a transfer recording medium having a structure in which a reaction initiator that acts upon receiving heat and light energy and a polymerizing component are mixed at a portion under pressure. Is applied under the condition corresponding to the halftone recorded information, pressure, heat and light energy are applied to form a transfer image similar to the case of the above (1). A mode of transferring in the same manner as the above.

In the transfer step, the transfer recording medium on which such a transfer image is formed is brought into contact with the transfer receiving medium and heated from the transfer recording medium or the transfer receiving medium side, so that a portion having a high melting point, that is, a high molecular weight is polymerized. A halftone image is formed by selectively transferring a transfer image having halftone information, which is formed by the distribution of the melting point due to the non-polymerized part and the part not sufficiently polymerized, to the transfer medium. To do.
Therefore, the heating temperature in this transfer is set to such a temperature that only the transferred image having the halftone information is selectively transferred and the transfer amount is transferred by reflecting the halftone information of the transfer recording medium. There is a need.

It is also effective to apply pressure at the same time in order to efficiently perform the transfer. Pressurization is particularly effective when using a transfer medium having a low surface smoothness. The physical properties that govern the transfer characteristics are
When the viscosity is at room temperature, transfer is possible only by applying pressure.

The above example shows the case where the melting temperature or the like of the portion to which a plurality of types of energy are applied becomes high, but as a transfer recording medium, a sensitive component that is softened by receiving a plurality of types of energy or has a low melting temperature or 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, some examples of processes of the halftone image forming method of the present invention will be described with reference to FIGS.

FIG. 2 is a schematic diagram showing one embodiment of the halftone image forming method of the present invention in which a transfer image is formed using light and heat energy.

1 is a recording layer containing a transfer recording layer containing an image-forming element whose melting point or softening point increases depending on the heating state by irradiating light in a molten state or a softened state by heating. Ink donor film (IDF) which is a transfer recording medium formed by 2 is a supply roll around which IDF1 is wound,
3 is a light irradiating 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 a thermal head for generating a heat pulse by a control circuit 5 based on an image signal. Etc. are heating means. The magnitude or length of the heat pulse to the heating means 4 is controlled according to the halftone recording information. It is also possible to use an energized heat 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 energizing. This heating means 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 is an energizing head). There is. 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.

8 is a heat roll equipped with a heater 7 inside, and 9
Is placed facing the heat roll 8 and is a plain paper, OH
A pinch roller that presses the transfer medium 10 such as a P-sheet and the IDF1 together, and 11 is a take-up roll that winds the IDF after transfer recording, where IDF1 is Tg ₀ , Tg ₂ , Tg ₃ <Tr < The recording image 12 is heated to a temperature Tr satisfying Tg ₁ and is transferred onto the transfer medium 10 to be separated from the IDF 1.

FIG. 3 is a schematic view showing another embodiment of the halftone image forming method of the present invention in which a transfer image is formed by light, heat and pressure.
The IDF1 used in this case is mixed with the polymerizing component by the photoreaction initiator contained in the capsule being cleaved, and the same as in the previous embodiment depending on the magnitude of light and heat energy to be applied. A transfer recording layer containing an image-forming element whose melting point or softening point is increased is arranged on the film. 13 is an ID in the transfer image forming process
This is an ultraviolet-transparent pressure-bonding member for breaking the capsule by applying a pressure to F1 almost uniformly, and a member using quartz glass or the like can be used. Other configurations are the same as those shown in FIG.

FIG. 4 is a schematic view showing one embodiment of the halftone image forming method of the present invention in which a transfer image is formed by light and heat energy. In this embodiment, contrary to the case of FIG. 2, light irradiation is controlled based on the image signal, and heat is uniformly applied.
Therefore, 14 is a heater that heats IDF1 uniformly,
A heat roll such as No. 8 may be used, or a ceramic substrate provided with a heater may be used. 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 emits light by a control circuit based on an image signal, which is selected according to the spectral sensitivity of the transfer recording layer. When it has sensitivity in the visible light range, an LED array,
Examples include laser arrays and liquid crystal shutter arrays. 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 basically light that is excellent in responsiveness and can reduce diffusivity because it is controlled based on the image signal,
It is easy to obtain image quality at high speed and with clear gradation.

FIG. 5 shows a modified embodiment of the image forming method of the present invention in which a step of applying pressure to the IDF 1 is provided before the transfer step. Basically, it is almost the same as the case of FIG. That is, the third
A pressure roller 16 is provided in place of the ultraviolet-transparent pressure-bonding member 13 shown in the figure, and pressure is applied to the IDF 1 before the transfer image formation so that the IDF 1 can react with light and heat energy. Starting with the IDF1 used, the others are the same as in the case of FIG.

Further, in addition to a pigment and a dye, a color former or a color developer that develops the color former may be used as the colorant 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, when it contains a coloring agent such as a pigment or dye that does not use a coloring reaction, it is generally excellent in the preservability of the medium before recording and the image storability after recording, and at the same time, it is of high quality with high color reproducibility It is easy to get an image of.

〔Example〕

 Hereinafter, the present invention will be described more specifically based on Examples.

Example 1 90 parts by weight of an image-forming element composed of the components shown in Table 1 was dispersed in 10 parts by weight of a binder, and the thickness was 6 μm.
A transfer recording medium having a dry film thickness of 3 .mu.m was formed on the polyimide film as above to form a transfer recording layer, which was wound into a roll and incorporated as a supply roll into the transfer device shown in FIG.

The thermal head 4 is a line type of A4 size of 8 dots / mm and has a heating element array arranged at the edge part. The transfer recording medium is arranged so that the base material side is in contact with the heating resistor and the transfer is performed. The tension of the recording medium 1 was pressed against the heating resistor. On the other hand, a 2 kw high-pressure mercury lamp was placed 2 cm away from the transfer recording medium at a portion facing the heating element.

Using such a device, negative recording was performed according to halftone recording information. That is, the control of the thermal head 4 is performed by the control circuit 5 when the mark signal is the strongest (black), not energized, and when the mark signal is weak or absent (white to gray), heat is generated. The energy applied to the heating element of the thermal head 4 was about 0.8 w / dot for 4 msec depending on the halftone recording information. In this way, the thermal head 4 is controlled and driven according to the image signal while uniformly irradiating the light with the high pressure mercury lamp, and the transfer recording medium is synchronized with the stepping motor and the drive rubber roll in a repeating cycle of 5 msec / line. Transported.

In this way, the transfer recording medium 1 on which the transfer image formed by partially raising the melting point of the image forming element is formed is conveyed to the transfer step, and the transferred surface is a plain paper having a surface smoothness of 10 to 30 seconds. The medium 10 was superposed on the transfer image forming surface of the medium to be transferred, and the heat transfer was carried out by the heat roll 8 and the pinch roll 9. The heat roll 8 is an aluminum roll having a built-in heater of 300 W, the surface of which is coated with silicon rubber having a thickness of 2 mm and a hardness of 80 °, and the heater is controlled so as to keep the surface at 90 to 100 ° C. The pinch roll 9 facing the heat roll 8 is an aluminum roll covered with a silicone rubber roll having a hardness of 50 °, and a pressure of 1 to 1.5 kg / cm ² is not shown between the heat roll 8 and the pinch roll 9 so as not to be shown. It was adjusted by the mechanism.

The recorded image formed in this manner was clear and had excellent fixability and gradation expression.

Example 2 10% by weight of microcapsules in which p-phenylenebis (α-cyanobutadienecarboxylic acid), which is a polymerization initiator, is wrapped with a wall agent capable of being cleaved by pressure, the following formula: Unsaturated polyester resin having a polymerized unit represented by
80% by weight and 10% by weight of carbon black are mixed in a solvent (methyl ethyl ketone) to form a transfer recording medium having a transfer recording layer by a solvent coating method on a polyester film having a thickness of 6 μm so that the dry film thickness is 5 μm. did.

The microcapsules were prepared by mixing p-phenylenebis (α-cyanobutadienecarboxylic acid) and paraffin oil in 200 ml of distilled water together with 1 g of a nonionic surfactant having an HLB value of 12, gelatin 1 g, and gum arabic 1 g. After mixing and stirring at 8000 to 10000 rpm with a homomixer, pH is set to 11 or more by adding ammonia to obtain a microcapsule slurry, which is then solid-liquid separated with a Nutsche filter and vacuum dried at 35 ° C. It was dried in a machine for 10 hours to obtain microcapsules. The size of the obtained microcapsules is such that the average particle size is about 10 μm and the initiator mixed with paraffin oil is coated with gelatin and gum arabic.

This transfer recording medium is wound into a roll and incorporated into a transfer device as a supply roll, and the transfer recording medium is supplied while being adjusted so that a pressure of ^{2 to 4} kg / cm ² is applied between the glass plate and the rubber roller. From the side of the glass plate, an argon laser with a wavelength of 488 nm is used to record ² to 5 mJ / cm ² according to the halftone recording information.
The laser beam was scanned through the polygon mirror with the energy of 1 to form a transfer image on the transfer recording medium.

In the transfer step, the same transfer medium as that used in Example 1 was overlaid on the transfer image forming surface of the transfer recording medium, and the surface was covered with silicon rubber while adjusting so that a pressure of 1 kg / cm ² was applied. The transfer was performed by sandwiching the heat roll and the pinch roll and controlling the surface temperature of the heat roll to be 100 to 120 ° C.

The recorded image thus formed was a high-quality image that was clear and excellent in gradation expression.

Example 3 10% by weight of microcapsules containing methyl ethyl ketone peroxide, which is a polymerization initiator, prepared by the same method as in Example 2 and wrapped with a pressure-cleavable wall agent, 80% by weight of unsaturated polyester resin, and lake red. C10% by weight
Is mixed in a solvent (methyl ethyl ketone) and the thickness is 3.5μ
A transfer recording medium provided with a transfer recording layer by a solvent coating method so that the dry film thickness was 5 μm was formed on a polyimide film of m.

This transfer recording medium is wound into a roll and incorporated into a transfer device as a supply roll, and the transfer recording medium is supplied while being adjusted so that a pressure of ^{2 to 4} kg / cm ² is applied between the thermal head and the rubber roller. A transfer image was formed by supplying 0.8 w / dot of energizing energy as a heat pulse of 1 to 3 msec to the heating resistor of the thermal head according to the halftone image signal.

In the transfer step, the same transfer medium used in Example 1 was overlaid on the transfer image forming surface of the transfer recording medium, and silicon rubber having a surface hardness of 45 ° was prepared while adjusting the pressure of 1 kg / cm ^2. Transfer was carried out by sandwiching a roll coated with an aluminum core material with a thickness of 3 mm and a similar heat roll having a heater inside, and controlling the surface temperature of the heat roll to be 80 to 100 ° C.

The recorded image thus formed was a high-quality image that was clear and excellent in gradation expression.

〔The invention's effect〕

As described above, in the present invention, a transfer recording medium having an image forming element whose melting point, melt viscosity, or the like, which is a characteristic that governs transfer characteristics only when a plurality of types of energy are simultaneously applied, is used. Since the transfer is performed after the transfer image is formed, the stability to the environment is higher and the stability is always higher than that in the conventional method in which transfer is performed only by applying heat affected by the environmental temperature. It becomes possible to obtain a highly accurate image, and 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 response of the system, and it takes a long time to give the energy required for image formation to the transfer recording medium by 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, since the transfer image is formed by a plurality of types of energy, it becomes easy to adjust the degree of change in physical properties forming the transfer image stepwise, and stable and highly accurate halftone image recording can be performed.

Further, since the step of forming a transfer image, the step of transferring and the step of fixing are independent, conditions suitable for transferring the transfer image to the transfer medium with high quality and stability are set. Can be set independently of and. Therefore, as the transfer medium, not only plain paper but also a wide range of transfer media such as low surface smoothness paper and transparency can be applied to obtain a high-quality image, and at the same time, the fixing property is improved. It has become possible.

[Brief description of drawings]

1a to 1f are graphs for explaining the principle of forming a transfer image by light and thermal energy. Second
FIG. 5 to FIG. 5 are schematic views each showing an embodiment of the image forming method of the present invention. 1: Transfer recording medium, 2: Supply roll 3: Lamp, 4: Thermal head 5: Control circuit 7: Heater, 8: Heat roller 9: Pinch roller, 10: Transfer medium 11: Take-up roll, 12: Recorded image 13: UV transparent pressure bonding member 14: Heater, 15: Lamp array 16: Pressure roller

Claims (1)

[Claims] 1. A physical property that governs a transfer characteristic is changed by applying a plurality of types of energy, and the transfer characteristic is changed according to the magnitude of energy of at least one of the plurality of types of energy. In a transfer recording medium having an image forming element in which the degree of change of the physical properties that change is changed in a transfer recording layer, at least one kind of energy of the plurality of kinds of energy is supplied under a condition according to halftone recording information. A halftone image forming method, comprising: a step of applying a plurality of types of energy while changing the rate to form a transfer image on a transfer recording layer; and a step of transferring the transfer image to a transfer medium.