JPH0120992B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thermal transfer recording device, and particularly to a thermal transfer recording device that can transfer and record images with gradation and color images. In recent years, with the development of information systems, various output formats are required for hard copies. In particular, there is a strong demand for colorization of hard copies, colorization of soft copies, and colorization of displays to accommodate the diversity of information. Furthermore, recording devices for obtaining these hard copies are required to have excellent operability, maintainability, and reliability, as well as to be compact and low-noise. In response to these demands, thermal recording devices using thermal recording paper are now widely used in facsimiles, printers, and the like. However, since thermosensitive recording paper contains coloring bodies in the paper itself, when a plurality of coloring bodies are included in the same paper, it is necessary to set the coloring temperature ranges of each coloring body so that they do not overlap. Therefore, it is not possible to superimpose multiple colors on the same surface, and it is also difficult to obtain gradation of density in each color, so it is difficult to obtain a color image obtained by superimposing monochromatic images with gradation. It is difficult to obtain with thermal recording. On the other hand, there is a thermal transfer recording device that can superimpose a plurality of colors by taking advantage of the advantages of thermal recording and using ink carriers of different colors.
The basic configuration of this device is shown in FIG. That is, the heat-melting colored ink layer 1 is placed on the base film 2.
The ink carrier 3 coated on the recording medium is placed on the recording medium 4 so that the colored ink layer 1 is in contact with the surface of the recording medium 4, and these are supplied between the platen rubber roller 5 and the thermal head 6. The carrier 3 and the recording medium 4 are connected to the thermal head 6.
The colored ink layer 1 is heated and melted by the thermal head 6 from the base film 2 side of the ink carrier 3 while being pressed against the base film 2 side. Since the heated and melted ink adheres to the recording medium 4, by separating the ink carrier 3 and the recording medium 4, an image 7 of the transferred ink is obtained on the recording medium 4. However, as is clear from FIG. 1, since the ink is peeled off from the interface between the base film 2 and the ink layer 1, most of the ink is transferred to the recording medium 4. It is quite difficult to control the amount of transcription. Therefore, in thermal transfer recording using conventional heat-melting ink, it is difficult to realize recording with density gradation, and color recording is also difficult. On the other hand, a thermal transfer recording method is also known in which a thermal printing unit sublimates and adheres the dye to a receiving sheet using an ink carrier on which an ink mainly composed of a dye with a sublimation temperature of less than 80°C is adhered to a base film. There is (Special Publication 51-23182). However, there is no disclosure of a method for obtaining an image with gradation. Transfer printing, textile printing (Special Publication No. 48-11409, etc.) and thermal copying method (Japanese Patent Publication No. 39-18793, etc.) using sublimation dyes are also known, but all of them have arbitrary gradation. No method of obtaining images is suggested. The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a thermal transfer recording device capable of producing an image with gradation or a color image on any recording medium. This invention uses an ink carrier that supplies a sublimable coloring material, and varies the heating time to control the amount of the sublimable coloring material that is sublimated and released and transferred to a recording medium according to the heating time. This makes it possible to obtain tonal images and color images. Fig. 2 shows an example of the relationship between the time when electricity is applied to the heat generating resistor of the head as a heating means in a thermal transfer recording device and the recording density of the transferred and recorded image, where the solid line A indicates the color material that is heat sublimable. This is the case where an ink carrier is used, and the broken line B is the case where an ink carrier having a conventional heat-melting coloring material is used. In the case of A using an ink carrier containing a sublimable coloring material, the recording density gradually changes depending on the length of the current application time, but in the case of B using an ink carrier containing a heat-melting ink. , it can be seen that the recording density changes rapidly after a certain energization time. That is, in the case of B, since the time width in which the concentration changes is extremely narrow, it is practically difficult to select it corresponding to each concentration. On the other hand, in the case of A, since the energization time range that causes a predetermined density change is wide, the time range that corresponds to the density can be easily selected, and an image with gradation can therefore be easily obtained. Become. FIG. 3 shows an embodiment of the present invention. As an ink carrier 13, a sublimable coloring material 11 is used as a base film 1.
2 is used. During recording, the ink carrier 13 is used as the sublimable coloring material 11 as in the conventional case.
is supplied between a platen rubber roller 15 and a thermal head 16 serving as a heating means in a state where it is overlapped with the recording body 14 so as to contact the surface of the recording body 14,
The ink carrier 13 and recording medium 14 are moved relative to the thermal head 16 while being pressed against the thermal head 16 by the platen rubber roller 15. Then, the heating resistor of the thermal head 16 is energized to generate heat, and the heat sublimates the sublimable coloring material 11 to form the base film 1.
2. The sublimable coloring material liberated in this way is received and transferred to the recording medium 14, thereby obtaining an image 17 on the recording medium 14. Here, the heating resistor of the thermal head 16 is
The gradation recording signal 18 controls the ON/OFF state of the energization and also controls the energization time.
As a result, when the sublimable coloring material 11 in the ink carrier 13 is released from the base film 12 and transferred to the recording medium 14, the amount of the transferred color changes in accordance with the gradation recording signal 18, so that eventually the recording body 14
As the image 17 obtained above, it is possible to obtain an image with gradation and density changes according to the recording signal 18. The method of supplying current to the heat generating resistor of a thermal head is usually a pulse current supply method having a time width within a range that does not damage the heat generating resistor over time. on the other hand,
The gradation of the original signal of the recording signal is expressed by its voltage value, and methods for converting this into the energization time to the heating resistor include analog conversion and digital conversion. Here, digital conversion will be explained as an example. FIG. 4 shows an example of a method for digitally converting the original signal voltage, which is the output of a reading element that optically reads the density of a document, into the energization time to a heating element. From the relationship between the output voltage value of the reading element and the original density shown in Figure 4a, and the relationship between the energization time to the heat generating resistor of the thermal head and the recording density shown in Figure 4b, the appropriate Select the recording density by several steps. Here, we set this number of steps to 4.
Explain as steps. Furthermore, in general, the correspondence between the reading element output voltage value and the energization time requires γ correction, but this will be omitted here. In short, depending on the selected recording density D ₁ , D ₂ , D ₃ , D ₄ , the read element output voltage values V ₁ , V ₂ , V ₃ , V ₄ and the energization times τ ₁ , τ ₂ , τ ₃ , τ The relationship with ₄ can be determined.
Specifically, as shown in Figure 4c, the output voltage value of the reading element is determined using four reference voltages V ₁ , V ₂ , V ₃ , and V ₄ , and the determination results are applied to the heating resistor as shown in Figure 4d. These are converted into reference current application times to the body τ ₁ , τ ₂ , τ ₃ , and τ ₄ respectively.
The gradation recording signal 18 is, for example, the fourth
It is applied to the thermal head 16 as a pulse train whose pulse width varies according to FIG. d. As a result, as shown in FIG. 4e, it is possible to obtain an image 17 with gradations expressed in four levels of recording density: D ₁ , D ₂ , D ₃ , and D ₄ . In the present invention, the sublimable coloring material in the ink carrier is generally fixed to the base film by a binder, and in this case, the relationship between the sublimation point of the sublimable coloring material and the softening point of the binder is important. This is because if the softening point of the binder is lower than the sublimation point of the sublimable colorant, the binder will begin to soften and melt before the sublimable colorant begins to sublimate due to heating, and the sublimable colorant layer containing the binder will start to soften and melt. This is because almost the entire amount is transferred onto the recording paper, and even if the heating time is changed, the recording density will change close to that shown by the broken line B in FIG. 2, making it difficult to record with gradation. Therefore, it is necessary that the sublimation point of the sublimable colorant be lower than the softening point of the binder that fixes the sublimable colorant to the base film. The sublimable coloring material in the present invention has a sublimation point of 70°C to 400°C.
The temperature range is preferably 200°C or less, particularly preferably 200°C or less. The product name is TS as a sublimable coloring material.
−Blue 603 [Sumitomo Chemical Co., Ltd.], Kayalon First Orange, Kayalon First Blue, Kayalon First Green [Nippon Kayaku
Co., Ltd.], Diamonds Fast Yellow [Mitsubishi Chemical Industries, Ltd.], Eisen QZ Red [Hodogaya Chemical Co., Ltd.], etc., quinarizan dyes, dispersed monoazo dyes, dispersed anthraquinone dyes, dispersed nitrodiphenyls. Examples include sublimable dyes such as amine dyes, anthracene dyes, and smoke dyes, and coloring substances using sublimable substances as carriers. on the other hand,
Recording materials that accept sublimation coloring materials include plain paper such as medium-quality paper and high-quality paper, nylon, polyester, polyimide, polyvinyl chloride, polycarbonate,
Plastic films such as polystyrene, polypropylene, synthetic paper, plain paper coated with synthetic resin, metallized or laminated paper or sheets can be used. The properties of the recording medium are related to the stability of the recorded image on the printable recording medium. The following table shows the results of comparing the stability of recorded images when thermally transferred to various types of recording media using an ink carrier using a coloring material containing a sublimable dye with a sublimation point of 90°C.

【table】

[Table] However, ◎ is very good, ○ is good, △ is fair,
× indicates defective, and * eraser test means rubbing with sand eraser 20 times.
From this result, the recording medium used in the present invention is as follows:
It can be seen that polyester resin, polyvinyl chloride resin sheet, or resin-treated paper having an ink-receiving layer treated with these resins is particularly preferable. The heating means for heating the ink carrier in the present invention is not limited to a thermal head. For example, when a laser device is used as a heating means, the number of times the same point is irradiated is changed depending on the gradation recording signal by taking advantage of the fact that the number of laser irradiations on the ink carrier is proportional to the recording density. A recorded image with gradation can be obtained. Other heating means may be selected as required, such as a thermal pen or thermal printing type. As described above, according to the present invention, recorded images with gradation can be easily obtained. Also,
Since the basic configuration is the same as that of conventional thermal transfer recording devices, it can also be used for binary recording and is highly flexible. Furthermore, according to the present invention, by taking advantage of the fact that a recorded image with gradation is obtained, and by preparing a plurality of ink carriers each supplying a sublimable coloring material of a different color, multi-color or full-color recording is possible. You can also do this. FIG. 5 schematically shows an example of the configuration of a color thermal transfer recording apparatus as another embodiment of the present invention. A thermally sublimable cyan ink carrier 13a, a magenta ink carrier 13b, and a yellow ink carrier 13c are arranged in order in the traveling direction of the recording medium 14, and in this order, thermal heads 16a,
Color information 19a, 19 by 16b, 16c
The coloring material is transferred to the recording medium 14 according to the colors b and 19c. As shown in FIG. 6, the coloring material transferred to the recording medium 14 is a single color or a layered mixture of colors. For example, a portion 21 where three colors are mixed becomes black, and a portion 22 where cyan and yellow are mixed becomes green. In FIG. 6, C indicates the transferred color material, M indicates the transferred color material, M indicates the magenta, and Y indicates the transferred color material. In this way, full colors can be expressed by varying the amount of each coloring material.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional thermal transfer recording device.
FIG. 2 is a diagram comparing the relationship between current application time and recording density when using a heat-fusible ink carrier and a sublimable ink carrier, and FIG. 3 is a schematic diagram of an embodiment of the present invention. FIG. 4 is an explanatory diagram of its operation, FIG. 5 is a schematic diagram of another embodiment of the present invention, and FIG. 6 is a diagram showing how a color image is obtained on a recording medium in the same embodiment. 11...Sublimable coloring material, 12...Base film, 1
3, 13a-13c... Ink carrier, 14... Recording body, 15... Platen rubber roller, 16, 16a-
16c... Thermal head, 17... Transferred recorded image, 18... Gradation recording signal, 19a to 19c...
Color information.

Claims (1)

[Scope of Claims] 1. An ink carrier for supplying a sublimable colorant, a heating means for heating the ink carrier to sublimate the sublimable colorant and liberate it from a base film of the ink carrier; In a thermal transfer recording device comprising a recording body that receives a sublimable coloring material released from a base film of an ink carrier, the heating time of the heating means is variable, and the heating time is changed according to a recording signal to print the ink carrier. A thermal transfer recording device characterized in that it is configured to further control the amount of sublimable coloring material liberated. 2. The thermal transfer recording device according to claim 1, characterized in that the heating time of the heating means is controlled according to the gradation recording signal to obtain an image with gradation on the recording medium. . 3 A plurality of ink carriers supplying sublimable coloring materials of different colors are provided corresponding to a common recording medium, and the heating time of the heating means for heating each of these ink carriers is controlled according to the color information of the recording signal. 2. A thermal transfer recording apparatus according to claim 1, wherein a color image is obtained on a recording medium. 4. The thermal transfer according to claim 1, wherein the heating means is a thermal head having a heating resistor, and the heating time is made variable by controlling the time during which electricity is applied to the heating resistor. Recording device. 5. The ink carrier is a heat sublimable coloring material fixed onto a base film using a binder,
2. The thermal transfer recording apparatus according to claim 1, wherein the sublimation point of the sublimable coloring material is selected to be lower than the softening point of the binder. 6. The thermal transfer recording device according to claim 1, wherein the recording medium is a sheet made of polyester resin or polyvinyl chloride resin, or resin-treated paper treated with these resins.