JPS61217263A - Thermal recorder - Google Patents

Abstract

PURPOSE:To make uniform and effective the transmission of thermal energy between a thermal head and a sheet-shaped member by applying, evaporating or impregnating a material fluidified through heating on the sheet-shaped member and heating the member for thermal recording. CONSTITUTION:Sheet-shaped member is thermally heated directly by a heating means such as thermal head 1 or other recording paper 4 indirectly using the sheet-shaped member as a medium. The sheet-shaped member such as ink donor film 22 has a material 223 which is thermally fluidified formed in thin film or impregnated on a surface contacting the heating means. The side thermal fluidified layer 223 which contacts the thermal head 1 in the sheet-shaped member such as ink donor film 22 is thermally fluidified so that the film becomes solid again after passing through a recording section. The member is not a material which is always liquedified and as such it is handled easily. Besides it does not foul the unit or an operator's hand.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a thermal recording device for thermally recording using a heating means such as a thermal head.

``Prior Art'' With the spread of office equipment such as computers and facsimile machines, recording of various types of information has become more and more commonplace. There are various recording methods for recording such various information. Among these, thermal recording devices that perform recording or display using thermal pulses have an excellent feature in that they can be manufactured inexpensively and compactly, and are widely used.

Typical thermal recording methods include a thermosensitive color recording method and a thermal transfer recording method. In these methods, recording is performed by applying a thermal pulse to a thermal recording paper or a thermal transfer recording medium using a heating means such as a thermal head.

Among these, in the thermal color recording method, recording is performed directly on a thermal recording paper, and in the thermal transfer recording method, recording is performed on a recording paper that is overlapped with a thermal transfer recording medium.

FIG. 1O shows the main parts of an example of a recording apparatus that performs recording using a thermal transfer recording method. An ink donor film 3 and a recording paper 4 are supplied in a superimposed state between a line type thermal head 1 and a counter roll 20 arranged in parallel therewith. As shown, the opposing roll 2 comes into contact with the recording paper 4 and serves to press it against the thermal head 1 via the ink donor film 3. Heat and transferable ink is applied to the surface of the ink donor film 3 on the side that contacts the recording paper 4, and when a heat pulse is applied to the ink donor film 3 by the thermal head 1, the corresponding part of ink will be transferred to the recording paper 4. The opposing roll 2 is rotated by a minute angle in the direction of the arrow in the figure each time one line is recorded, thereby performing sub-scanning. The recording paper on which recording has been completed and the ink donor film are separated at a location not shown, and the recording paper is ejected to a discharge tray, also not shown.

FIG. 11 is an enlarged view of the contact area between the thermal head and the ink donor film in such an apparatus. The heating element 5 of the thermal head 1 is formed on a ceramic substrate 6 and is further covered with a wear-resistant layer 7. The thickness of the wear-resistant layer is about 5 μm.

By the way, as shown in FIG. 11, the thermal head 1
The surface of the abrasion resistant layer is not completely smooth, and the same is true of the ink donor film 3 that comes into contact with the abrasion resistant layer. Therefore, gaps inevitably occur at these boundary areas, and air exists in these areas. If air exists between the thermal head 1 and the ink donor film 3, thermal energy will not be properly transferred to the ink donor film 3 in this area, resulting in blurred recording or density unevenness. Furthermore, there are cases where it is not possible to sufficiently increase the density of an image due to defective ink transfer due to poor thermal energy transfer, and it has generally been difficult to stably obtain high image quality due to the above reasons.

Therefore, in Special Publication No. 52-20142, sheet-like members (
In this case, a technique is disclosed for improving the adhesion with the thermal head 1 by increasing the smoothness of the thermal paper (in this case, thermal paper). Specifically, the smoothness of the top layer surface of thermal paper is expressed as Beck smoothness of 2.
00 to 1000 seconds to improve the color development of thermal paper.

Also, on page 90 of the magazine Nikkei Electronics 1983.2゜28, a technique is disclosed in which the surface of the thermal head 1 is polished closely and the heating element 5 is made into a protrusion to improve its adhesion to the sheet-like member. has been done. However, with any of these techniques, it is difficult to bring the sheet-like member such as the ink donor film 3 into stable contact with the thermal head 1 without any gaps, and it is inevitable that gaps of up to about 1 μm will occur in various places. Ta.

JP-A-59-196293 discloses an invention to solve the problem of thermal energy transmission failure caused by air existing in such a gap.

In this invention, the liquid substance is interposed between the base film constituting the sheet-like member and the thermal head, thereby filling the gap (void) described above with the liquid substance. This achieves uniform transmission of heat pulses and efficient heat conduction.

However, this liquid substance is supplied by an independent supply device. That is, for example, as shown in FIG. 12, a transfer sheet (sheet-like member) 1 is transferred from a tank 12 containing a liquid substance 11 such as silicone oil using an applicator roll 13.
4, or connect the tank 15 to the thermal head 1 through a pipe 16 as shown in FIG.
It is discharged from 7.

``Problems to be Solved by the Invention'' Thus, in this invention, a liquid substance is supplied to a sheet-like member to fill the voids with the liquid.

Therefore, a device for supplying the liquid substance is required, and when the thermal recording device is moved, there is a risk that the liquid substance will spill into the device.

In view of these circumstances, the present invention provides a thermal recording device that does not require a device for replenishing the liquid substance itself, and that makes the transfer of thermal energy between the thermal head and the sheet-like member uniform and efficient. Its purpose is to provide.

"Means for Solving the Problems" In the present invention, a sheet-like member is coated, vapor-deposited, or impregnated with a substance that becomes fluidized by heating, and thermal recording is performed while heating this with a heating means. Since the gap between the heating means such as a thermal head and the sheet-like member is filled with the fluidized substance, thermal energy is transferred uniformly and efficiently. Moreover, not only when the sheet-like member is coated or impregnated with a substance that becomes fluidized by the heat of potash, but also when this is coated or impregnated within the apparatus, there is no need for a device to replenish the liquid substance itself. .

"Example" The present invention will be described in detail with reference to Examples below.

"First Embodiment" FIG. 1 shows the main parts of a thermal recording apparatus according to a first embodiment of the present invention. This device supplies roll paper tube 2.
The ink donor film 22 unwound from 1 is guided by a guide roll 23, passes between the thermal head 1 and the opposing roll 2, and further passes between the drive roll 24 and the pinch roll 25, and is transferred to the take-up roll paper tube 26. It is designed to be rolled up. On the other hand, recording paper (plain paper) 4 is sent out one by one from a supply tray (not shown) and is overlapped with the ink donor film 22 near the guide roll 23. Then, as the ink donor film 22 is moved in the direction of the arrow by the drive roll 24, it passes between the thermal head 1 and the opposing roll 2, and thermal transfer recording is performed at this time.

The recording paper 4 on which recording has been completed is separated from the ink donor film 22 when passing through the drive roll 24, and is discharged to a discharge tray (not shown).

FIG. 2 shows an example of the structure of an ink donor film used in this device. This ink donor film 22A has an ink layer 222 formed on one side of a base material 221, and a heated liquefied layer 223 formed on the other side. The ink layer 222 is set in the thermal recording device so as to be in contact with the recording paper 4 (FIG. 1). That is, the heated liquefied layer 223 comes into contact with the heated portion of the thermal head 1.

The base material 221 of the ink donor film 22A is, for example, a polyethylene film or capacitor paper, and its thickness is, for example, 6 μm. The ink layer 222 is formed by applying a conventional thermal transfer ink that melts or sublimates upon heating to a thickness of, for example, 3 μm, and the melting point of the thermal transfer ink is, for example, 64'''C.

The heating liquefaction layer 223 is a layer with a thickness of about 1 μm coated with a substance that is solid at room temperature and liquefies when heated. High melting point waxes and crystalline polymers are suitable as these substances. The melting point and softening point need to be 180°C or less in relation to the temperature during heating of the thermal head 1, the melt viscosity is preferably 100 COpoise or less, and the surface energy is preferably about 35 dyne/cm or less. .

Examples of such substances include low molecular weight polyethylene and polyethylene wax with an average molecular weight of 10,000 or less, low molecular weight polypropylene and polypropylene wax with an average molecular weight of 20,000 or less, and their oxides and halides. There are modified products and derivatives of.

In addition, the substances constituting the heated liquefied layer 223 include higher fatty acids of wax materials, fatty acid metal salts (e.g. zinc stearate, calcium stearate), fatty acid esters, fatty acid amides, higher alcohols, fluorine wax, silicone grease, etc. , silicone resin, and surfactant may also be used. When a surfactant is used, in addition to its original role of increasing thermal energy efficiency, it can also have an antistatic function.

Since the heating liquefied layer 223 is intended to improve thermal conductivity, a thermally conductive filler that contributes to this may be mixed into the above-mentioned materials. Such as A, ff2
03 (aluminum oxide), BN (boron nitride), S+
Ch (silicon dioxide), 5iC (silicon carbide), 5iN
(-nitride-silicon), B, C (boron carbide), T102
(Titanium dioxide), ZoO (zinc oxide), carbon black, graphite, ferrite, and other inorganic fine powders, inorganic fibers, etc. are suitable. In addition, if it is necessary to prevent the filming (adhesion) of wax or the like on the thermal head 1, for example, Al2O2 with a diameter of 1 μm or less is mixed into the polyethylene wax for liquefaction at a weight ratio of about 30% to form a heated liquefied layer. 223 may be formed. Such a heated liquefied layer has a polishing effect and can stabilize the performance of the thermal head 1 for a long period of time. The heating liquefaction layer for polishing does not need to be formed on the entire surface of the ink donor film 22A;
For example, they may be formed with a width of 5Qcm every 10m.

The ink donor film 2.2A described above can be manufactured by applying a thermally transferable ink to one side of the base material 221 and applying a heated heated liquefied substance to the other side. After the thermal transferable ink and the heated liquefied substance are solidified and their layers 222 and 223 are formed, they are wound up onto a supply roll paper tube to complete a supply roll to be set in the apparatus. The thermal transfer ink can also be applied by a conventional solvent coating method or hot melt coating method.

Application of a heated liquefied substance by a hot melt coating method is not necessarily suitable for forming a thin layer of about 1 to 2 μm as in this example, and a solvent coating method is suitable. In the case of a solvent coating method, for example, a low molecular weight wax or the like is dissolved in a solvent such as toluene and coated. In the case of polyethylene wax, etc., it is coated by dissolving it in hot decalin, hot toluene, etc. It is also possible to perform the coaching infrastructure with an aqueous emulsion or dispersion of waxes. If the particle size of the emulsion or dispersion is made small, it is easy to coat it in a thin layer.

Note that when the base material 221 is, for example, a polyethylene film, ordinary non-polar wax does not necessarily have good adhesion.

-COOH in such a case.

Introducing polar groups such as -01(, -X (halogen), NH2, etc. as the heated liquefied layer 223 is effective for forming a good layer. Examples of such groups include oxidized polyethylene wax, oxidized polypropylene wax, ester wax, etc. Of course, it is also possible to form the heated liquefied layer 223 by depositing a heated liquefied substance on the base material 221.

Experimental example Thermal transfer recording was performed under the following conditions.

■Thermal head: Thick film thermal head with 300 dots/inch and Δ3 size width.

■Ink donor film: The base material is a 6μm thick polyethylene sheet that has been heat-resistant to over 260°C. A wax with a melting point of 64°C was applied to this surface using the solvent method at a coating amount of 3.4/m2 to form a heated liquefied layer.

■Recording paper: Ordinary high-quality paper with a surface smoothness of approximately 100 seconds.

■Opposing roll: A rubber roll with a diameter of 25 mm using a rubber material with a hardness of 45 degrees and a stainless steel core with a diameter of 13 mm. A
Press a 3-size sheet with 8 kg against the thermal head.

■Thermal head drive = 2.4m5ec/line drive.

As a result, the energy of the applied pulse per dot was reduced to 0.1
I was able to make good recordings by setting it to 8W x 0.7mS. When an ink donor film without the heating liquefaction layer 223 was used under the same conditions, almost the same density (dot diameter) was obtained by increasing the energy of the applied pulse to 0.25 W x 0.7 mS. In other words, in this example, the energy per 1 mm2 was reduced from 19 mJ to 1
It was possible to reduce it to 3.4 mJ. Moreover, as shown in FIG. 3 corresponding to FIG. 11, the heated liquefied layer 223 is temporarily liquefied at the location where the applied pulse is supplied,
and wear-resistant layer 7 completely. Therefore, in the ink donor film 22Δ of this example, the density unevenness that occurs in the ink donor film without a heating liquefaction layer did not occur, and the image quality was uniform. In addition, the images became sharper and clearer.

"Second Embodiment" FIG. 4 shows the main parts of a thermal recording device in a second embodiment of the present invention. In this figure, the same parts as in FIG. 1 are denoted by the same reference numerals, and their explanation will be omitted as appropriate. In this device, the same ink donor film 3 as conventionally used is wound around the supply roll paper tube 21. That is, in this ink donor film 3, as shown in FIG. 5, an ink layer 222 is formed on one side of a base material 221, but a heating liquefaction layer is not formed on the other side. The ink donor film 3 fed out from the supply roll paper tube 21 is placed between the thermal head 1 and the opposing roll 2 with its ink layer 222 side facing the opposing roll 2.
The paper passes between the paper tubes and is wound up onto a take-up roll paper tube 26.

Incidentally, in this apparatus, a coating roll 32 is provided between two guide rolls 31 and 23 that guide the ink donor film 3 to the recording section, and is in contact with the base material 221 of the ink donor film 3. A guide plate 33 having a predetermined inclination is arranged near the coating roll 32. A solid heated liquefied substance 34 is placed on the guide plate 33, and its tip portion is constantly in contact with the application roll 32 due to its own weight.

The application roll 32 is a silicon roll with a built-in heater, and when a print start button (not shown) of the apparatus is pressed, electricity is started and rotation is started. The heating liquefied substance 34 may be the same substance as the substance pointed out in the previous embodiment as a material that can constitute the heating liquefied layer, and the coating roll 3
The contact portion is melted by heating 2 and applied to the ink donor film 3. The applied heated liquefied substance 34 solidifies again on the surface of the base material 221, forming an ink donor film having the same structure as the ink donor film 22A shown in FIG. The heated liquefied substance 34 of the ink donor film 3 is liquefied when heated by the thermal head 1, and plays the same role as described in the previous embodiment.

Note that in the apparatus of this second embodiment, a coating roll 32 may be arranged instead of the guide roll 23.

In this case, the solid heated liquefied substance 34 may be pressed upward against the coating roll 32 using a spring or the like. Depending on the device, the guide roll 23 may have a built-in heat source to ensure uniform application of the heated liquefied substance 34 and also to coat the ink layer 222.
It is also possible to preheat the

"Possibility of Modification of the Invention" In the first and second embodiments described above, a layer of a heat-liquefied substance that liquefies when heated is formed on one side of the ink donor film to improve heat transfer. It may also be used to impregnate a shaped member.

FIG. 6 shows the case of an ink donor film, and this ink donor film 22B is made of a fibrous base material 22.
4 is impregnated with a heated liquefied substance 36. Heat-sensitive recording paper can also be coated or impregnated with heat-liquefied substances.

Figure 7 shows another example of capsule 3 containing a substance that is liquid at room temperature.
7 shows an ink donor film 22C in which the capsules 37 are placed in a base material. The capsule 37 will melt or rupture upon heating, and liquid will be supplied to the thermal head. Capsule 37 is base material 2
They may be arranged in layers on one side of 25. A similar configuration is possible in the case of thermal recording paper.

FIG. 8 shows a modification of the recording section. In this modification, grooves 39 are provided on both sides of the thermal head IA, which is disposed facing the opposing roll 2. This is to release the excess when the amount of heated liquefied substance is large. Since the temperature of the groove 39 increases due to the heat storage effect of the thermal head IA, the heated liquefied substance can be collected in a tank (not shown). Since the heated liquefied material solidifies when the device is powered off, the heated liquefied material will not spill out during transportation of the thermal recording device.

Finally, FIG. 9 shows another example of a mechanism for applying a heated liquefied substance to a thermal head. A heated liquefied substance 42 is contained in the tank 41, and is heated and liquefied by a heater (not shown) when the device is powered on.

The liquefied heated liquefied substance 42 is transferred to a pair of rotating application rollers 43.
．． 44 to the base material 221 of the ink donor film 3 (
(see Figure 5). In this example as well, since the heated liquefied substance 42 solidifies when the device is not in use, there are no inconveniences that occur with conventional devices.

"Effects of the Invention" As explained above, according to the present invention, the side of a sheet-like member such as an ink donor film that comes into contact with the thermal head is fluidized by heating, so that it solidifies again after passing through the recording section. Therefore, unlike substances that are always in a liquid state, they are easy to handle, and in this respect, they do not stain the equipment or the operator's hands. In addition, in the present invention, by applying the heated liquefied substance to the sheet-like member within the apparatus, the sheet-like member is preheated immediately before the recording section, so the energy applied to the heating element of the thermal head can be reduced, and the head can have a long lifespan. can be further extended.

[Brief explanation of drawings]

1 to 3 are for explaining the first embodiment of the present invention, of which FIG. 1 is a schematic configuration diagram of a thermal recording device;
FIG. 2 is a side view of the ink donor film, FIG. 3 is an enlarged explanatory view showing the contact area between the ink donor film and the thermal head, and FIGS. 4 and 5 are for explaining the second embodiment of the present invention. 4 is a schematic diagram of the thermal recording device, FIG. 5 is a side view of the ink donor film, and FIGS. 6 to 9 show various modifications of the present invention.
Of these, Figures 6 and 7 are side views of the ink donor film, Figure 8 is a sectional view of the recording section, Figure 9 is a principle diagram showing another coating principle of the heating liquefied substance coating mechanism, and Figure 10. ~
Figure 13 is for explaining a conventional thermal recording device.
Of these, Figure 1O is a side view of the recording section in the thermal transfer recording method, Figure 11 is an enlarged explanatory view of the contact area between the ink donor film and the thermal head in Figure 10, and Figure 1
FIG. 2 is a schematic diagram of a thermal recording device using a coating roll, and FIG. 13 is a schematic diagram of a thermal recording device that supplies liquid through a pipe. 1...Thermal head, 3.22...Ink donor film, 4...
... Recording paper, 32.43.44 ... Application roll, 36.42
...Heat liquefied substance, 37...Capsule, 221.224.225...Base material, 222...
... Ink layer, 223 ... Heating liquefaction layer.

Claims (1)

[Claims] 1. Using a heating means and a sheet-like member whose surface in contact with the heating means is formed into a thin film or impregnated with a substance that becomes fluidized by heating, the sheet-like member is heated from the heating means. A thermal recording device characterized in that thermal recording is performed directly on a member or indirectly on another recording paper using this sheet-like member as a medium. 2. The sheet-like member is a thermal recording medium for performing thermal transfer recording, and the thermal transferable ink applied to the surface of the thermal transfer recording medium opposite to the side heated by the heating means is melted or 2. The thermal recording apparatus according to claim 1, wherein recording is performed by sublimating the ink and transferring the ink to a recording surface disposed opposite to the ink. 3. The multicolor recording device according to claim 1, wherein the sheet-like member is a heat-sensitive recording paper for recording using a heat-sensitive coloring method. 4. The thermal recording device according to claim 2, wherein a substance that becomes fluidized by heating is applied in advance to the surface of the supporting base of the thermal recording medium. 5. The thermal recording device according to claim 1, further comprising coating means for coating the thermal recording medium with a substance that becomes fluidized by heating. 6. The thermal recording device according to claim 2, wherein the thermal recording medium contains a substance that is solid at room temperature and becomes fluid when heated. 7. A microcapsule that fluidizes or ruptures when heated contains a liquid therein, and is disposed on one surface of the thermal recording medium on the side that comes into contact with the heating means. The thermal recording device according to item 2.