JPS6295258A - Printing apparatus - Google Patents

Abstract

PURPOSE:To provide a high speed and high quality thermal transfer recording apparatus without choice in the surface configuration of a receiving article, by constituting the title apparatus so that an ink heating means and an ink pressure transfer means are not operated at the same time. CONSTITUTION:The current supply thermal transfer film 13 delivered from a film supply roller 43 is contacted with a recording electrode 20 at the edge part 60 of a current supply recording head 21 and the resistance layer 14 of said transfer film 14 is strongly pressed to the recording electrode 20. At time time, because a substrate 80 is an elastomer, the selected part of an ink layer 11 is heated and melted by the current supply heating of the resistance layer perfectly independent of the surface state of receiving paper. Because ink has a hysteresis characteristic, a time is provided from a heating process to a transfer process and the ink holds melt viscosity even if cooled to the vicinity of room temp. by the atmosphere and, therefore, said ink can be transferred to receiving paper 12 by the pressure of a transfer mechanism 46. Because the leading end of the transfer mechanism has such a structure that a plurality of elastic fine wires 83 are embedded in a base part, the ink 11 of the current supply transfer film can be contacted with and pressed to the receissed parts 33 of the receiving paper.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a printing device using a thermal transfer recording method.

[Prior Art] As shown in FIG. 11(a), the thermal transfer recording method selectively heats and melts heat-melting ink 11 coated on a film-like substrate 10 using a thermal head 15 having an energized heating element 16. This is a printing method in which the ink 11 is simultaneously polymerized onto the transfer target 12 and transferred under pressure to obtain an image.

Further, FIG. 4(b) is a diagram for explaining an electric thermal transfer method which is a modification of the above-mentioned thermal transfer method, in which the film-like substrate 10
From a recording head 21 having an ink transport body 13 having the heat-melting ink 11 on one side and an energizing heat generating layer 14 on the other side, and a recording electrode 20 for passing a current through the energizing heat generating layer 14. Become.

Each recording method has features such as silent printing, the use of pigment-based ink, high-density printing, easy color printing, easy line-forming of the recording head, and high-speed printing. .

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, although good printing can be obtained for objects with smooth surfaces, it is not possible to obtain good impressions for objects with rough surfaces. There was a problem that a print could not be obtained.

The cause will be explained with reference to FIG. First, the heated and melted ink 31 does not come into contact with the concave portion 32 of the transferred object 12, so that a dot is missing. Secondly, since a gap 33 is created between the recording head 15 and the conveying body, heat cannot be efficiently transferred to the ink under the gap in the case of a thermal transfer method.
In the case of the energized thermal transfer method, the electrical contact between the recording electrode and the energized heat generating layer deteriorates, so that the ink is not melted sufficiently, resulting in defective transfer.

To solve the above problem, there is an idea to make the recording head an elastic body and make it follow the rough surface of the transfer paper, but since the recording head needs to be heat resistant, this idea is suitable for low-speed printing devices with little temperature. can only be applied.

Particularly, bond paper, which is used for official documents in Europe and the United States, cannot be printed due to the above-mentioned reasons, which is a factor preventing the spread of thermal transfer methods.

The present invention is intended to solve these problems, and its purpose is to provide a high-speed, high-quality thermal transfer recording device that can be used regardless of the surface shape of the object to be transferred.

[Means for Solving the Problems] The printing apparatus of the present invention is characterized in that the ink heating means and the pressure transfer means do not operate at the same time.

[Embodiment] FIG. 1 is a diagram showing the structure of an electric thermal transfer printing device in an embodiment of the present invention. Marked in Figure 1(a).

The overall mechanism of the ear device is shown in Fig. 1(b) and Fig. 1(a).
An enlarged view of the area within the broken line 41 is shown. Further, the conveyance speed of the transfer paper and the electrically conductive thermal transfer film was approximately 57 mm/sec. This corresponds to the speed at which 12 sheets of A4 paper can be printed in one minute.

Reference numeral 12 denotes a transfer paper, which is supplied by a transfer paper supply roller 42 . Reference numeral 13 denotes an electrically conductive thermal transfer film, which is fed out from a film supply roller 43, undergoes a printing process, and then is wound up by a film take-up roller 44. The structure of the electrically conductive thermal transfer film 43 includes a base layer 10 made of a 6 μm thick polyethylene terephthalate film (PET), a resistance layer 14 coated on one side of the base layer, and an ink layer 11 coated on the other side. The resistance layer 14 is made by dispersing 20% by weight of carbon powder in a resin. The resistance value was approximately 1.07 cm2. The ink 11 has a hysteresis characteristic in the relationship between temperature and viscosity as shown in FIG. 2. When the ink used is heated from room temperature, the viscosity decreases as shown by curve 50 in FIG. 2 and changes from the same phase to the liquid phase. However, even after cooling to room temperature, the liquid phase remains for a certain period of time as shown by curve 51. The retention period of the liquid phase of the ink used in this example was approximately 0.2 m5e.
It was c. Reference numeral 46 denotes a transfer mechanism for transferring the ink to the transfer paper, which holds and presses the transfer paper 12 and the electrically conductive thermal transfer film 13 between it and a platen 47. Transfer mechanism 4
6 is a brush-shaped tip 54 as shown in FIG. 1(b).
is fitted into the guide 53, and the tip 54 is pressed against the platen by a spring 55 from within the guide. Furthermore, an electric heater 56 for heating the transfer mechanism and a temperature sensor 57 for monitoring the temperature of the transfer mechanism are installed on the back near the tip of the transfer mechanism. 58 is a fulcrum for stabilizing the path of the electrically conductive thermal transfer film.

Reference numeral 21 denotes a current-carrying recording head consisting of a recording electrode 20 and its support 58. Reference numeral 80 denotes a base upon which the electrically conductive thermal transfer film 13 is pressed by the recording head 21. Recording electrode 20
In order to have good contact with the resistance layer 14, the material is sufficiently smooth and elastic, and a material to which the molten ink 11 does not adhere is used. In this embodiment, silicone rubber was used as the material.

Note that the recording frequency was set to 1 and 5 m5ec/Line.

Further, the distance from the contact point of the recording head with the energized thermal transfer film to the contact point of the transfer mechanism with the energized thermal transfer film is approximately 5 mm.Next, the effect of the above structure will be described. The energized thermal transfer film 13 fed out from the film supply roller 43 comes into contact with the recording electrode 20 at the edge portion 60 of the energized recording head 21 .

At this time, the resistive layer 14 of the current-carrying thermal transfer film is pressed more strongly against the recording electrode 20 by the a side 81 pressing the tip of the recording head against the current-carrying thermal transfer film 13 . At this time, the base 8
0 is an elastic body, so even if the linearity of the etched portion 60 of the recording head is somewhat poor, it can be followed without any problem. Therefore, good current conduction is possible between the recording electrode 20 and the resistance layer 14, and of course it does not depend on the surface condition of the transfer paper at all. In this manner, the selected portions of the ink layer 11 are heated and melted by the heat generated by energizing the resistance layer 140. Hereinafter, the process of heating and melting the ink by the recording head will be referred to as a heating process, and the process of transferring ink to the paper to be transferred by a transfer mechanism, which will be described later, will be referred to as a transfer process. In addition, the applied energy was determined to be such that the temperature of the ink within the area of the dot desired to be transferred was 70° C. or higher, taking into account the characteristics of the ink shown in FIG.

This is because when the ink has a viscosity of about 2000 CPS or less during transfer, it blends well with the surface of the paper to be transferred and has good adhesion.

As mentioned earlier, ink has hysteresis characteristics as shown in Figure 2, so there is a time delay (approximately 9 omsec in this example) from the heating process to the transfer process, and the ink is cooled to near room temperature by the atmosphere. Since it maintains its molten viscosity even when transferred, it can be transferred to the transfer paper 12 by applying pressure with the transfer mechanism 46. However, if the room temperature fluctuates, the temperature of the ink during transfer also changes and the optimum viscosity for transfer cannot be stably maintained, so the ink is appropriately heated through the transfer mechanism by an electric heater 56 and a temperature sensor 57 on the back of the transfer mechanism. In this example, the room temperature changes! liJ] -5 to 45°C
On the other hand, the temperature of the ink during the transfer process is 30-60°C.
It was controlled so that If the temperature is below 30°C, the viscosity of the ink melted during heating will increase, making transfer unstable.
Furthermore, if the temperature exceeds 60°C, the viscosity of the ink that is not melted during heating will cause smearing.

The tip of the transfer mechanism has a plurality of thin elastic wires 83 connected to the base 84.
embedded in. By adopting such a structure, it becomes possible to contact and press the ink 11 of the electrically conductive thermal transfer film also against the recessed portions 33 of the transfer paper. In this embodiment, tungsten wires 83 having a diameter of 100 μm were cut into 5 mm lengths and embedded in a resin base 84 in four rows at a pitch of 200 μm. When a tungsten wire is used, there are effects such as good heat conduction when performing the temperature control and less sliding wear with the resistance layer 14. By the way, the width of the concave portion of transfer paper (for example, bond paper) having a Bekk smoothness of 10 seconds or less is 50 to 200 μm, the depth is about 50 μm, and the distribution thereof is wide. Therefore, it was more effective to use the wire system of the above-mentioned elastic thin wire of 50 to 200 μm. In addition, the platen 47, which serves as the base upon which pressure transfer is performed by the transfer mechanism, should be hard in order to apply pressure efficiently.

In this example, the effect was further enhanced by using NBR with a hardness of 50 degrees or more.

By pressurizing the heated ink onto the paper to be transferred by the transfer mechanism having the above structure, the ink sufficiently contacts even the recesses on the surface of the paper to ensure ink transfer.

When we actually attempted printing using the configuration of the present invention described above, we found that while conventional printing was only possible on thermal transfer paper with a Beck smoothness of 200 seconds or more, it was possible to print well on bond paper with a Beck smoothness of 8 seconds or more. Good printing was possible.

[Effects of the Invention] As described above, according to the present invention, by separating the heating process and the transfer process, the range of selection of mechanisms for the heating method and the transfer method is expanded, and it is possible to transfer materials with rough surfaces. It is also effective for obtaining good prints.

Although this embodiment has been explained by taking the electrical thermal transfer recording method as an example, the present invention has similar effects in the thermal transfer recording method as well.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the structure of a printing apparatus according to the present invention. FIG. 2 is a diagram showing the characteristics of the ink used in this example. FIG. 3 is a diagram explaining the conventional problem. FIG. 4 is a diagram showing a conventional thermal transfer recording method. 12... Transferred object 13... Thermal transfer film 20... Recording electrode 21... Recording head 46... Transfer member 56... Heater 57... Temperature sensor or higher

Claims (1)

[Claims] A film-like recording medium having a layer of ink activated by thermal stimulation and selectively pressure-transferred to a printing medium, means for selectively heating the ink, and heating the ink activated by the heating means. 1. A printing device comprising pressure transfer means, wherein the ink is selectively heated on a substrate that does not have adhesive properties with the ink activated by the thermal stimulus.