JPS60264295A - Thermal transfer recording apparatus - Google Patents

Abstract

PURPOSE:To enable high quality printing, by using ink expanding by heating as the heat-meltable ink of an ink ribbon. CONSTITUTION:A substance generating thermal expansion at predetermined temp. is used in the ink of an ink ribbon. The ink 24 heated by a thermal head 21 expands by the gas, which is generated by the thermal decomposition of the blowing material contained in the ink 24, simultaneously with the softening of said ink or after softening and the ink reaches even the part, not contacted with the ink 24, of recording paper 22 and the adhesion of the ink in the heated region is secured. The heat resistance of the heated region abruptly increases by gas bubbles 30 due to the generated gas and the rising in the temp. of the ink except the heated region by the heat accumulation of the thermal head 21 is prevented and the adhesion of the ink to an unnecessary part is prevented. Even when the uneveness of an ink receiving surface is large, accurate ink transfer is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thermal transfer recording device, and particularly to a thermal transfer recording device with improved ink transferability to recording paper.

[Technical background and problems of the invention]

An ink ribbon coated with ink that is solid at room temperature and recording paper are overlapped with the ink side interposed, and a thermal head on the back of the ink ribbon selectively heats the ink according to the recording signal, softening the ink. Thermal transfer recording method, in which the material is melted and attached to recording paper and transferred, is being put to practical use in OA-related terminal equipment such as printers for CRT terminals, printers for personal computers, and word processor printers. There is an increasing demand for printers in this field to be capable of high-quality printing even on inexpensive plain paper commonly used in offices, such as PPC paper, or to be capable of color printing. However, in the hot melt type thermal transfer recording method, the ink surface of the ink ribbon and the surface of the recording paper are in pressure contact and the ink is attached.
Irregularities on the surface of recording paper greatly affect ink adhesion and transfer characteristics, that is, print quality. Generally, the surface of PPC paper has unevenness ranging from several micrometers to several tens of micrometers, making it difficult to clearly print complicated Chinese characters. In addition, in color printing, for example, as shown in Japanese Unexamined Patent Publication No. 57-174276, in order to obtain the necessary color by overlapping yellow and magenta fans, after the transfer of - color ink is completed, this transfer This is equivalent to forming an uneven surface on the surface of the recording paper using ink. Therefore, when transferring the second and subsequent colors, in most cases it must be applied to an uneven surface, and the adhesion is more reliable than monochrome printing.

Transferability is required. In particular, when color printing is performed using PPC paper, etc., the unevenness of the surface of the recording paper is also added, resulting in problems such as line breakage at the edge interface with the previously transferred ink or color unevenness, which can cause problems with thermal transfer recording devices. could not take full advantage of its advantages.

[Purpose of the invention]

This invention was made in view of the above-mentioned problems, and the PP
I'm a big fan of high-quality fp printing on inexpensive recording paper like C paper! The purpose is to do something.

(BeT red and white) + vomit τ [Summary of the invention] This invention is a method of heating the ink ribbon by heating means such as a thermal head provided on the back surface of the ink ribbon while the ink-applied surface of the ink ribbon and the recording paper are superimposed and pressed into contact with each other. 2. Description of the Related Art A thermal transfer recording device that performs recording by selectively applying heat to ink in accordance with a recording signal to adhere and transfer the ink to a recording paper or the like uses a substance that thermally expands at a predetermined temperature as the ink of the ink ribbon.

This material can be realized, for example, by a material containing a thermally foamed material. Any material may be used as long as it causes discontinuous portions 1, such as bubbles, in the ink when heated.

〔Effect of the invention〕

According to the present invention, it is possible to obtain high-quality printed records regardless of the roughness of the surface of the recording paper without adding any mechanical addition to the conventional thermal transfer recording device ψ.

[Embodiments of the invention]

Hereinafter, this invention will be explained in detail with reference to the drawings.

FIG. 2 shows an embodiment of the thermal transfer recording apparatus according to the present invention. Reference numeral 1 designates an ink ribbon, on which a substrate serving as an ink carrier is coated with ink that is solid at room temperature, softens or melts when heated, and at the same time rapidly expands thermally.

Such inks consist of a colorant, a binder, and an intumescent material. As the coloring material, any coloring material commonly used in the fields of printing and copying, such as pigments such as carbon black or various dyes, can be used.

Paraffins with various melting points are used as binders.

Waxes such as carnauba wax, beeswax, and candelilla wax, low molecular weight petroleum resins, high molecular polymers such as polystyrene, styrene-butadiene copolymers, and cellulose testers such as ethyl cellulose and cellulose acetate butyrate are used. Ru.

As the expansion material, one that expands rapidly at a predetermined temperature or upon heating is used. Such materials include foamed materials that generate gas upon thermal decomposition or self-oxidizing compounds such as nitrocellulose that combust rapidly when heated.

Foaming materials include organic foaming materials such as diazoamino derivatives, azo compounds, sulfone hydrazide compounds, and nitrone compounds;
Inorganic foaming materials include sodium bicarbonate, ammonium carbonate, and azide. As specific examples of organic foaming materials, diazoamino derivatives include 1.3. Bis-low biphenylyl triazine, diazoaminobenzene, 1-methyl-3-phenyl triazine, azo compounds such as azobishexahydrobenzodinitrile, azobisinbutyronitrile, diazoacetamide, sulfone hydrazide compounds such as benzenesulfone Acid hydrazide.

4.41-Bis(hydrazinosulfonyl)diphenyl ether and nitroso compounds include N,N'-dinitroso-N, Nl-dimethylterephthalamide, and the like. The thermal decomposition temperatures of these foam materials can be obtained over a wide temperature range from 60°C to 200°C or more. A foaming aid may be used in combination to lower the decomposition temperature and promote decomposition of the organic foam material. Unsaturated fatty acids and urea are used as foaming aids.

Urea derivatives, lead stearate, etc. are used.

For example, by using salicylic acid for dinitropentamethylenetetramine, which has a thermal decomposition temperature of 260°C or higher, the decomposition temperature can be lowered to about 100°C.

The properties of the foam material used in this invention are (1) that the decomposition temperature is not too high above the softening or melting temperature of the ink, especially the binder (2) that the decomposition rate is fast (
3) It has good storage stability. (4) It does not generate harmful gases. If the decomposition temperature is lower than the softening or melting temperature of the binder, the ink softens.

Foaming occurs before melting, and the resulting bubble layer acts as a heat insulating layer, impeding heat transfer, preventing the softening and melting state required for ink to adhere to recording paper, and thus adversely affecting transferability. cause deterioration. Since the softening temperature or melting temperature Tm of the ink or binder is usually set at 55°C to 150°C, the degree of decomposition Tg is 60°C to 160°C, and Tm≦
It is preferable to set it as Tg.

In addition, in a thermal transfer recording device, the ink heating time is usually less than IQms, and the ink cooling time is also several m8, so the time the ink is in a softened and molten state is about 1Qms, and the decomposition reaction progresses within this time. There is a need. As the substrate of the ink ribbon 1, a thin paper such as polyester, a polymer synthetic film with polyimide corners, or a capacitor paper can be used. For synthetic films if necessary.

A heat-resistant protective layer such as nitrocellulose may be provided on the surface opposite to the ink-applied surface.

The thickness of the substrate and ink layer that can be suitably used in this invention is desirably 20 μm or less and 10 μm or less, respectively.

A specific example of an ink ribbon for thermal transfer recording having such a structure is, for example, one in which 10% by weight of azobishexahydrobenzodinitrile is dispersed in a binder solution consisting of 60% by weight of carnauba wax and 40% by weight of a low molecular weight petroleum resin. Apply the ink solution mixed and dispersed with Car Pump 2222% by weight to a 6μ polyethylene terephthalate film,
One example is an ink ribbon for serial printers having a width of 8 m and having an ink layer of 4 μm thickness. 2 is a thermal head in which 24 heating elements (not shown) are arranged at a density of 7 dots/blend, and each heating element is arranged in a line perpendicular to the scanning direction of the thermal head 2. 3 is high quality recording paper.

Although medium-quality plain paper, 0) IF base paper, etc. can be used, PPC paper with a Beck smoothness of 50 seconds is supplied here. 4 is a platen roller that cooperates with the thermal head 2 to transfer the thermal head 2, ink ribbon 1. The recording paper 3 is held in a pressed state.

When not printing, a paper conveying motor (not shown) coupled to the platen roller 4 works to convey the recording paper 3 held on the platen roller 4 by a certain amount by a paper pressing roller (not shown). 5 is an ink ribbon guide pin, 6 is an ink ribbon peeling guide, 7 is an ink ribbon supply reel, and 8 is an ink ribbon take-up reel. It is installed on a carriage 9 together with the round head 2. The carriage 9 can be moved in a direction perpendicular to the paper feeding direction of the recording paper 3 by a carriage drive means (not shown) K.

Next, the recording operation of such a thermal transfer recording apparatus will be explained. When the power of the apparatus is turned on, the carriage 9 is set to the home position. At this time, the ink ribbon 11 (thermal head) 2 is separated from the recording paper 3 by the thermal head pressure control means (not shown).The carriage 8 moves to the printing start point in response to the print signal, and the thermal head is urged in the direction of the platen roller 4 by a thermal head pressure control means (not shown), and the thermal head 2,
Ink ribbon 1. The recording paper 3 is brought into close contact with the recording paper 3, and the heating element of the thermal head 2 is selectively heated by a thermal head drive circuit (not shown), so that the ink on the ink ribbon 1 is softened or melted and adhered to the recording paper 3. . After heating, the carriage 9 is moved by a predetermined amount in the direction of arrow A.

The same amount of ink ribbon/1 as this moving amount is supplied from the ink ribbon supply reel 7, and as the carriage 9 moves, the ink ribbon peeling guide 6 moves the ink ribbon 1
is peeled off from the recording paper 3, and the ink is transferred. The used ink ribbon is wound onto an ink ribbon take-up reel 8. The ink ribbon take-up reel 8 is coupled to an ink ribbon take-up means (not shown) and rotates to apply tension to the ink ribbon 1. By repeating this operation, when printing for one line is completed, the ink ribbon
The thermal head 2 is moved away from the recording paper 3 by a thermal head pressure control means (not shown), and the carriage 9 returns to its home position. During this time, the recording paper 3 is moved by one line by rotating the platen roller 4 in the direction of arrow B. By repeating these operations, a predetermined amount of printing is performed.

Next, the improvement of ink adhesion to recording paper, which is a feature of the thermal transfer recording apparatus according to the present invention, will be explained in detail. FIG. 1 schematically shows the state of ink when it is heated and when it is transferred to recording paper. FIG. 1(a) shows the case of a thermal transfer recording apparatus according to the present invention, and FIG. 1(b) shows the case of a conventional thermal transfer recording apparatus. 21 is a thermal head, 22 is a recording paper, 23 is an ink ribbon made of heat-melting foaming ink 24 and a base material 25, 26 is a conventional ink ribbon made of heat-melt ink 27 and a base material 25, 28. 29 is each transferred ink. 3o is a bubble generated by heating.

In the thermal transfer recording device of this invention, the thermal head 2
According to 1, the heated ink softens or melts at the same time,
Alternatively, the ink expands due to gas generated by thermal decomposition of the foamed material contained in the ink 24, and the ink reaches parts of the recording paper 22 that come into contact with the ink 24, as shown in FIG. and heating area (indicated by diagonal lines)
Ink adhesion is ensured. In addition, the thermal resistance of the heating area rapidly increases due to the bubbles 30 caused by the generated gas, which prevents the temperature of ink outside the heating area from rising due to heat accumulation in the thermal head 21, and prevents ink from adhering to unnecessary areas. In this way, even when the ink-receiving surface of the recording paper 22 has large irregularities, accurate ink transfer is performed.

On the other hand, in the conventional thermal transfer recording device, as shown in Fig. 2(b)
Ink 2 in the heating area (indicated by diagonal lines) as shown in K.
7 solidifies and is transferred without being able to come into contact with the recessed portions of the ink receiving surface of the recording paper 22, so that the transfer to the recording paper becomes inaccurate with respect to the heated area. Furthermore, since there is little change in thermal resistance in both heated and non-heated areas of the ink due to heat accumulation in the thermal head 21, there is a risk that ink may adhere outside the heated area. The present invention overcomes these drawbacks.

Next, a color thermal transfer recording apparatus which is another embodiment of the present invention is schematically shown in FIG. 31 is a thermal head in which 1728 heating elements are arranged in one example at a density of 8 elements/, 32 is a support plate of the thermal head 31, 33 is an ink ribbon peeling roller attached to the support plate 32,
These form a recording head assembly 34. 3
Reference numeral 5 denotes a platen roller made of silicone rubber having a hardness (JIS hardness) of 40°, which is arranged opposite to the recording head assembly 34, and is rotated by a step motor (not shown) at a predetermined paper feeding speed. Reference numeral 36 denotes a recording head assembly pressure control means that presses the recording head assembly 34 against or separates it from the platen row 235 by the action of a spring and an electromagnetic lever.

Four colors of ink, yellow, magenta, cyan, and black, are used in the longitudinal direction at 210 ma in 37 hours, and as mentioned above, the heat-melting and heat-foaming ink is repeatedly displayed at 300 mm pitch. It's an ink ribbon. The color ink ribbon 37 is attached to the ink ribbon supply roll 3
The ink ribbon winding is guided from 8 to guide rollers 39 and 40, passes between the recording head assembly 34 and the platen row 235, and is driven by a motor (not shown) via a peeling roller 33 and a guide roller 41. It is wound up on a take-up roll 42. 43 is recording paper, which is PPC paper.

The recording paper 43 is fed out from the recording paper supply roll 44 and is fed between the recording paper pressure contact roller 45 and the platen roller 35 in a state in which it is in close contact with the surface of the platen roller 35. Reference numeral 46 denotes an ink ribbon sensor, and an ink color determination circuit (not shown) identifies the color of ink according to its output.

Next, the recording operation of the apparatus will be explained. When a start signal is input, yellow ink is detected by the ink ribbon sensor 46, and the ink ribbon sensor 46 is set so that its tip is located at the heat generating element of the thermal head 31. At this time, the recording head assembly 34 is in a state separated from the platen row 235, and only the ink ribbon 37 is transported by the drive of the ink ribbon take-up roll 42. Thereafter, by the action of the recording head assembly pressure control means 36, the recording head assembly 34 is lowered to the thermal head 31° and the ink ribbon 37. Recording paper 43. The platen row 235 is brought into pressure contact and ready for recording.

The heating element of the thermal head 310 is selectively caused to generate heat by a thermal head drive circuit (not shown) in response to a recording signal corresponding to yellow recording from a recording information source (not shown). After printing one line, the rotation of the platen roller 35 causes the ink ribbon 37 and the recording paper 43 to be conveyed by one line without being displaced. Printing 2 Printing is performed from repetition K of paper conveyance. Partially adhered ink ribbon 37
The recording paper 43 is peeled off by the peeling roller 33, and the ink is transferred to the recording paper.

By pressing in this manner, one screen is first recorded using yellow ink. During this time, the ink ribbon 37 and recording paper 43
is transported at a constant speed.

After the yellow recording is completed, the recording head assembly 34 is separated from the platen roller 35. The recording paper 43 is set at the initial position by K when the step motor connected to the platen roller 35 is driven in the reverse direction at twice the forward speed and the same number of forward steps.

During this time, magenta ink is set on the ink ribbon 37 by driving the ink ribbon take-up roll 42. Ink ribbon 37. After setting the recording paper 43,
The recording head assembly 34 again moves down to the thermal head 3.
1. The ink ribbon 37, the recording paper 43, and the platen roller 35 are brought into pressure contact, and magenta recording preparation is completed.

Similar to yellow recording, the thermal head 31 is driven by a recording signal corresponding to magenta recording from a recording information source (not shown), and magenta ink recording is superimposed on yellow recording. Similarly cyan record.

Make a black record. With this color thermal transfer recording device, a color image with good gradation, no color unevenness, and excellent color reproducibility can be obtained. The improvement in adhesion of recording paper and ink when they are superimposed will be described in detail, which will clarify the characteristics of the color thermal transfer recording apparatus according to the present invention.

Figure 4 is a book that schematically shows the state of ink heating and the state of ink transferred to recording paper when magenta ink is superimposed on yellow ink for recording, and Figure 4 (a) is based on this invention. In the case of the thermal transfer recording device shown in FIG. 4(b),
is the case of a conventional thermal transfer recording device. 51 is a thermal head, 52 is a recording paper, 53 is a previously printed yellow ink, and 54 is a heat-melting foaming magenta ink 55
and a base material 56, 57 is a conventional color ink ribbon consisting of heat-melting magenta ink 58 and base material 56, 59 and 60 are respectively transferred magenta inks, and 61 is a color ink ribbon formed by heating. It is a bubble.

In the thermal transfer recording device of the present invention, the magenta ink (hatched portion) heated by the thermal head 51 is expanded by gas generated by thermal decomposition of the foaming material contained in the magenta ink 55, simultaneously with or after softening or melting. As shown in FIG. 3(a), the softened or melted magenta ink reaches even near the step on the end surface of the yellow ink 53 where the magenta ink 55 and the recording paper 52 are not in contact, and heats the area (hatched area). This ensures reliable ink adhesion. In addition, the thermal resistance of the heating area rapidly increases due to the bubbles 61 caused by the generated gas, which prevents the temperature of the ink from rising outside the heating area due to heat accumulation in the thermal head 51, prevents ink from adhering to unnecessary areas, and prevents ink from adhering to the color edges. You can get sharpness. on the other hand,
In the conventional color thermal transfer recording device, in the heating area (shaded area) as shown in FIG. , the magenta ink is transferred only onto the first-arrived yellow ink or onto the convex portions of the recording paper (magenta ink is missing in the dashed line area relative to the heating area), resulting in line breakage.

The color unevenness and image quality were significantly impaired.

When overlapping ink, the problem that the later printed ink does not contact the recording paper at the edge of the first ink often occurs even when the unevenness of the recording paper surface is extremely small (the thickness of the transferred ink is about 2μ to about (up to 6μ). Therefore, the color thermal transfer recording device of the present invention solves the problem of the melt transfer type thermal transfer recording device, which performs color recording by overlapping thick ink regardless of the unevenness of the ink-receiving surface of the recording paper. be.

Therefore, the recording medium may be plain paper as in the embodiment, but is not limited to this.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the percentage characteristics of ink transfer when using the ink ribbon of the present invention, and FIG. 2 is a schematic diagram of a thermal transfer recording device using the ink ribbon having the characteristics shown in FIG. FIG. 3 is a schematic diagram of a color thermal transfer recording apparatus to which the present invention is applied, and FIG. 4 is a diagram for explaining features of the color thermal transfer recording apparatus of FIG. 3. 1.23...Thermofusible 2-foamable ink ribbon, 2.
21...Thermal head, 3.22...Recording paper, 3
1.51...Line thermal head, 37, 54.
・・Thermofusible 9 foaming color ink ribbon, 43°5
2... Recording paper. Agent: Patent Attorney Noriyuki Chika (and 1 other person) No. 4
Figure-529-

Claims (3)

[Claims] (1) An ink ribbon coated with heat-fusible ink is placed over a recording medium, and the heat-fusible ink is selectively applied to the recording paper by thermal means in accordance with a recording signal. 1. A thermal transfer recording device that transfers images to obtain a recorded image, the thermal transfer recording device using an ink that expands upon heating as a heat-melting ink of an ink ribbon. (2) The thermal transfer recording device according to claim 1, wherein the ink ribbon is coated with a heat-melting ink containing a foaming agent. (3) The thermal transfer recording apparatus according to claim 2, characterized in that an ink ribbon is used in which the relationship between the thermal decomposition temperature Tg of the foam material and the softening or thermal melting temperature Tm of the ink is Tm≦Tg.