JPS6345955B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal transfer recording device that selectively transfers ink applied to a transfer master by heating, and particularly relates to an improvement of the ink application mechanism to the transfer master of this type of device. .

Thermal transfer recording has many advantages compared to normal thermal recording, such as better thermal responsiveness, the ability to record on plain paper, and excellent recording durability. There was a problem that the running cost increased due to consumption.

Therefore, as shown in FIG.
After selectively transferring and recording onto the recording paper 4,
It is conceivable that the ink can be used repeatedly by applying ink using the ink application mechanism 5.

As one of this type of device,
A device described in is known. In this case, as shown in FIG. 2, a cylindrical piece 12 of thermal ink is brought into contact with the ink-applied surface of the endless ribbon 11,
A high-temperature roller 13 is applied to this back surface to melt the ink of the heat-sensitive ink piece 12 and apply it to the endless ribbon 11.
Adjusted by.

However, according to this device, the thermal ink piece 12
Since a fixed amount of ink is overcoated regardless of the amount of residual ink on the endless ribbon, it is difficult to maintain the ink on the endless ribbon at a constant thickness without unevenness. or,
The thickness of this ink layer gradually increases, and in order to maintain a constant thickness, it is necessary to scrape off the ink on the endless ribbon, but in this way the excess ink is thrown away, making efficient use of ink. I couldn't do it.

However, if the thickness of the ink layer on the endless ribbon changes, the amount of ink transferred to the recording paper will change, resulting in a problem that a transferred image of uniform density cannot be obtained.

In addition, there are other types of ink applicators that are generally known, but these have a structure that pumps up ink using, for example, a combination of heat rollers in multiple stages, and are large in size. Since it is made for the purpose of coating onto a sheet to which no ink has been adhered, it is not suitable for repeated coating on a transfer master to which some of the ink has been transferred, as in the case of a thermal transfer recording device.

The present invention has been made in view of the problems of the conventional apparatus, and has a simple structure and can always keep the thickness of the ink layer on the endless transfer master constant, thus making it possible to maintain uniform density. It is an object of the present invention to provide a compact thermal transfer recording device that can obtain various types of transferred images.

The present invention is characterized in that (a plurality of) recesses are provided on the surface of a roller that pumps up ink melted by heating, the roller having the recesses is brought into pressure contact with a transfer master, and this pressed portion is heated.

Therefore, in the present invention, the shape of the concave portion of the roller,
Depending on the size, the amount of ink that can be accommodated in these is constant and the amount of transfer is constant, and the residual ink on the transfer master is removed by heating, so an ink layer of a constant thickness is always obtained on the transfer master. A transferred image with uniform density can be obtained.

By the way, the inventors have experimentally found that when a roller with a smooth circumferential surface is used as a roller for pumping up ink, the viscosity of the liquid heat-melting ink is low, and the relative relationship between the transfer master and the roller is low. If you reduce the speed and apply a surface pressure above a certain level,
It was confirmed that almost no ink adhered to the transfer master that came out after passing through this pressure contact area. Therefore, if a large number of minute recesses are provided on the circumferential surface of such a roller, the amount of ink that passes through the pressure contact portion and comes out on the opposite side is always limited to the volume of the recesses. If conditions such as the moving speed of the transfer master, the shape and size of the recess, and the materials of the ink and rollers are constant, the ink in the recess that has passed through the pressure contact area will always be transferred onto the transfer master at a constant rate. It was found that a coating amount of . The present invention was made based on this knowledge.

Examples of the present invention will be described below.

FIG. 3 shows the structure of a thermal transfer recording apparatus according to an embodiment of the present invention. The ink 22 stored in the tank 21 is pumped up by an ink pumping roller 23. Here, the ink 22 and the ink pumping roller 23 are heated to a temperature higher than the melting point of the ink by a heating means (not shown). Fine recesses 24 are formed almost uniformly over the entire surface of the ink pumping roller 23, and the ink 22 is pumped up by rotation in the direction of arrow a.

On the other hand, the endless transfer master 25 is indicated by the arrow b
It moves and rotates in the direction. An ink layer 26 is formed on the outer surface of the transfer master 25, and the ink of this ink layer 26 is selectively transferred to the recording paper in a recording portion (not shown). Therefore, in the ink layer that has passed through the recorded portion, ink remains partially as shown at 27. In this way, the transfer master 25 with the residual ink layer is pressed against the ink pumping roller 23 by the platen roller 28.
The platen roller 28 is also heated to a temperature higher than the melting point of the ink by, for example, a built-in heater, and melts the remaining ink on the transfer master 25 at the pressure contact portion.

The platen roller 28 is rotating in the direction of arrow c, and at the pressure contact portion, the melted residual ink on the transfer master 25 and the ink pumped up by the ink pumping roller 23 merge to form an ink layer of a predetermined thickness. form.

Although the platen roller 28 and the ink pumping roller 23 may be driven, only the transfer master 25 may be driven, and one or both of the platen roller 28 and the ink pumping roller 23 may be used as idlers.

Here, if we focus on the part of the ink pumping roller 23 and the transfer master 25 that are in pressure contact, by applying a surface pressure above a certain level, the ink that passes through this pressure contact part will essentially remain on the transfer master 25. It does not depend on the amount of ink drawn, but is limited to the volume of the recess formed on the ink pumping roller 23. The ink held in this recess is transferred to the transfer master 25 side at a constant rate when the ink pumping roller 23 and the transfer master 25 are separated on the exit side. The transferred ink may adhere to the transfer master 25 with some unevenness depending on the shape of the recesses on the ink pumping roller 23, but in this case, heat is applied as necessary by an appropriate heating means. By doing so, it is possible to impart fluidity to the ink and make the thickness of the ink uniform.

One method is to increase the contact distance with the heated platen roller 28. The ink layer thus formed is solidified before reaching the recording section.

By the way, the shape of the recess formed on the ink pumping roller 23 may be circular as shown at 31 in FIG. In addition, triangular, square, or hexagonal depressions, such as those used in gravure coaters, or spiral grooves with a triangular cross section can be freely selected.

A nylon cloth of 109 mesh is wrapped around the surface of the roller, which has a smooth surface, and a large number of recesses with a pitch of 233 μm are essentially formed.Ink with a melting point of 65°C is used, and a heater installed at the bottom of the ink tank is heated to a temperature of 150°C.
℃, the surface temperature of the roller 23 is 100℃, the surface temperature of the heat roller 28 whose surface is covered with heat-resistant rubber is 100℃ as the pressure means, the ink pumping roller 23 and the heat roller 28 are both Andrar, and the surface pressure is 30g/ cm ² , and the transfer master 25 is moved at 10 mm/sec to 40 mm/sec by a driving means (not shown).
When the transfer master 25 was reproduced, an ink layer with a thickness of 5 to 8 μm was formed. When this was recorded with a recording section having a thermal head of 6 lines/mm, a clear record was obtained.

In the above embodiment, the transfer master is an endless transfer master, but a long belt may be wound and used repeatedly.

Further, the heating means for melting the ink in the tank, the ink on the roller, and the ink on the used transfer master to be recycled consists of a heater and a heat roller provided below the tank as in the above embodiment. Ink pumping and pressure rollers may be used, or other forms may be used, such as those using radiation, such as heating with infrared lamps. or,
Some of these may be used in combination, or the entire regeneration device may be housed in a sealed container and the entire air within the container may be maintained at a high temperature.

As described above, in the present invention, a concave portion is provided on the circumferential surface of the roller that pumps up the ink, and the ink that is pumped up by this roller is heated at the part where it comes into pressure contact with the transfer master, and the remaining ink on the transfer master is heated. The ink is melted and integrated to form an ink layer of a constant thickness on the transfer master. Therefore,
According to the present invention, it is possible to obtain a compact thermal transfer recording device that can obtain a transferred image with uniform density.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a thermal transfer recording device that repeatedly uses a transfer master, FIG. 2 is a perspective view of a transfer master reproducing section of a conventional thermal transfer recording device, and FIG. 3 is a configuration diagram of an embodiment of the present invention. FIGS. 4a and 4b are diagrams showing the shape of recesses on the circumferential surface of an ink pumping roller according to an embodiment of the present invention. 21...Tank, 22...Ink, 23...Ink pumping roller, 24...Recess, 25...Transfer master, 26...Ink layer, 28...Platen roller.

Claims (1)

[Claims] 1 In a thermal transfer recording device that selectively transfers ink attached to a transfer master to recording paper by heating, there is a tank containing ink that melts by heating, and a peripheral surface partially immersed in the ink in this tank. A rotatable roller having a concave portion, a means for pressing the roller and the transfer master, and an ink heating means for keeping at least the ink in the portion pressed by the means and the ink in the concave portion of the roller in a molten state. A thermal transfer recording device comprising: