JPH02286272A - Thermal transfer recording device - Google Patents

Abstract

PURPOSE:To enable data to be thermally transferred to even paper with a low degree of smoothness, at high transfer efficiency and in excellent image quality by pressing a material to be transferred and a transfer medium using an adjacent pressure roller coated with an elastic material such as rubber immediately after the heating of a transfer medium with a recording head. CONSTITUTION:The pressure of a platen roller 1 and a pressure roller 2 is variable, and these rollers are equally loaded. In addition, the pressure can be cancelled out. Immediately after power is supplied to a recording head to print an image, a material to be transferred 9 and a transfer medium 4 are pressed with an adjacent pressure roller 2. After this, the material and the medium are peeled apart. A platen 1 should be as rigid as possible, and the surface is cured with metal or treated with a thin but hard rubber material. The surface of the pressure roller 2 is covered with an elastic material such as NBR, FPDM, CR, BR or silicon rubber. If the rubber material with a hard ness of 60 deg. to 90 deg. is used as a coating, it contributes to satisfactory image transfer.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to thermal transfer printers, copying machines, facsimile machines, and other thermal transfer recording devices, particularly relatively high-speed line-type thermal transfer recording devices that have low smoothness. The present invention relates to a thermal transfer recording device that can transfer good print quality and images even to plain paper.

[Conventional technology]

In recent years, thermal transfer recording has been used in many fields such as facsimiles, computer terminals, and recorders because it has the characteristics of being non-impact, noiseless, maintenance-free, low cost, small and lightweight, and capable of color printing.

Such a thermal transfer recording method melts and transfers ink onto a recording paper by heating the surface of the recording material with a thermal head or by heating an energized heat-generating resistive layer with a current-carrying head.
It provides prints or images, and a general configuration diagram of the vicinity of the recording section of the thermal transfer recording device is shown in FIG. 3.4.

However, when plain paper is used as the transfer paper, the transferability of this thermal transfer recording method is greatly influenced by the unevenness of the surface of the paper, the surface physical properties, the adhesive strength of the ink layer, the permeability, etc. Particularly in the case of paper with large surface irregularities, the thermally molten ink adheres only to the convex portions or the vicinity thereof, resulting in parts of the printed image being chipped off and degrading the print quality.

As a means to solve the above problems, it is possible to improve the composition and structure of the ink film, improve the paper contact by modifying the structure of the head, increase the contact pressure between the head and platen, or add vibration to the head. Various techniques have been proposed, such as adding

For example, regarding ink films, JP-A-60-264291, JP-A-60-26429
No. 5 or JP-A No. 61-244590, there are techniques in which a thermally decomposable or thermally expandable foaming agent is contained in the ink layer or release layer, and JP-A No. 63-67178. As shown in Japanese Patent Application Laid-Open No. 63-78792, etc., there is a technique in which a thermal transfer recording material is covered with a heat-melting coating material and an image forming element is thermally fused onto a substrate or exposed through a binding material. It has been devised.

Regarding heads, as shown in JP-A No. 58-59865, the glaze shape is raised in two stages to improve paper contact, and as shown in JP-A-61-110569, the glaze is formed on the edge of the substrate. Techniques for arranging heating elements have been devised.

Furthermore, in the printing mechanism, there is a method of setting the head pressure to a specific value or more as in JP-A No. 61-219665, and
-173956 or JP-A-61-164853
As shown in No. 2075, the aim is to heat the ink twice after transfer so that the ink penetrates into all four parts.
As in No. 9, a technique has been proposed in which a vibration oscillator is provided in the head and the transfer performance is improved by the vibration.

[Problem to be solved by the invention]

However, although improvements in printing quality have been seen with respect to the above-mentioned ink films and improvements in the head structure, they have not brought much effect even when used in conventional printing mechanisms.

In particular, regarding the printing mechanism, there was a drawback that when the head pressure was increased, the friction between the paper and the ink increased, causing background smearing, which significantly deteriorated the printing quality. In addition, the post-transfer heating method is based on the assumption that sufficient ink has been transferred to the paper during transfer, and with paper with low smoothness, it is important that the ink does not adhere to the paper surface during transfer. There was a problem.

Regarding the vibration method, there are doubts about its practical application, as it causes wrinkles in the ink transport.

Therefore, the present invention has been made in order to solve the above-mentioned problems regarding the printing mechanism and more clearly utilize the technologies proposed for ink films and thermal heads. It is an object of the present invention to provide a thermal transfer recording device using a new printing method that can print images with excellent print quality on low-smooth paper without causing such occurrence and placing no burden on the printing mechanism.

[Means to solve the problem]

In the thermal transfer recording device of the present invention, a recording head and a pressure roller whose surface is coated with an elastic body are opposed to the platen roller with the object to be transferred and the transfer medium interposed therebetween. It is characterized by a structure in which the transferred object and the transfer medium are pressed by adjacent pressure rollers, and then the transferred object and the transfer medium are peeled and separated.

The press force of the platen roller and the pressure roller is variable and uniformly loaded, and the press force can be released.

[Effect]

The surface unevenness of paper, which is generally called rough paper, is such that the depth of the grooves is 20 to 40 μm and the width of the grooves is about 200 μm. With conventional ink films, it was impossible to transfer only one dot into a deep and wide groove. This relationship is shown in Figure 5. In Figure 0, 9' is the paper surface, and the black area corresponds to one dot.As is clear from Figure 0, there is a high probability that the ink melted part will not come into contact with the paper. Naturally, there are irregularities in the paper that result in voids and self-drops in both the main scanning direction and the sub-scanning direction, and no matter how much pressure is applied with a rigid thermal head, the ink melting part does not come into contact with the paper surface. It is not possible.

In contrast, the recording apparatus of the present invention presses the ink surface with an elastic body such as a rubber body, and uses the elasticity to cause the ink layer to follow the unevenness of the paper surface.

An explanatory diagram is shown in FIG. 2. In Figure 0, reference numeral 2' denotes an elastic body of a pressure roller, which deforms to conform to the surface of the paper by pressure. The ink film that is the transfer medium has a support of 3 to 6 μm,
Since the ink layer is extremely thin at 1 to 5 μm, transfer to the uneven surface of paper is achieved without generating any rigid properties. 4a
is a preheated ink that can be pressed onto the paper surface and transferred neatly. After the transfer, the medium is peeled off from the paper surface along the pressure roller, and the ink 4a adheres to the paper surface side. At this time, in order to improve the peelability from the ink support film, a release intermediate layer may be inserted between the ink layer and the support.

〔Example〕

An embodiment of the present invention is shown in FIG. 1, in which 1 is a platen;
2 is a pressure roller. It is desirable for the platen to be as rigid as possible, and if the surface is treated with rubber, as in the conventional example, it is not desirable because it may cause conveyance misalignment or deformation of the platen, and therefore the surface may be more likely to be scratched. Metal hardening treatments are used to make them more durable, or surfaces are treated with extremely thin and hard rubber-based materials.

Pressure rollers are NBR, FPDM, CR, and BR.

The surface is covered with an elastic material such as silicone rubber.

- Covering the inside of the shell with a rubber material with a hardness of 60 to 90" will give better results in terms of transferability. However, since it also depends on the properties of the ink film, hardness cannot be determined unconditionally. difficult.

It also has a mechanism that can pressurize and release it. Also, it is more desirable to have an adjustment function that allows you to adjust the pressure depending on the type of paper used and the type of ink film.

Reference numeral 3 denotes a line thermal print head for recording, and in this embodiment, in order to shorten the distance between the recording position and the pressurizing position as much as possible, a head of a type in which a heating element is formed at the end of the head is used.

4 is an ink film, using a PET film as a support, and the ink layer is a mixture of a thermoplastic resin and wax with an appropriate amount of pigment added. In order to enhance the pressurizing effect, a material with a relatively long melting retention time after heating is used.

Furthermore, if an ink film with a foaming function is combined, it is predicted that even higher effects will be produced.

With this basic configuration, comparisons were made with the conventional example under various printing conditions.

(Example 1) The platen roller is made of stainless steel, the pressure roller is made of steel and coated with 60° NBR, the head is an A4 size product with a heating element formed at the head edge, and the ink film is Pigment content 20%
Using a monochrome film with a resin-rich composition,
Printing was performed under the following conditions.

(1) Platen-pressure roller pressure 2 to 12 kg/cm Total pressure 28 kg to 280 kg (2) Platen-head pressure Og to 40 g/cm Total pressure Og to 920 g/cm (3) Pulse period 3 m sec/li
n e (4) Applied energy 0.21 mj/dot (
5) Time from pulse application to pressurization 177 m5 (6) Platen diameter 40 mm in diameter (7) Pressure roller diameter 10 mm in diameter Rubber thickness 2 m
/ m In the above content, the higher the pressure roller pressure, the better the transfer efficiency, but bleeding was observed in the print quality, and the lower the head pressure, the less variation in the transfer rate. By examining the ink composition, it was confirmed that the print quality could be improved by increasing the resin content. Therefore, pressure roller pressure 1
0 kg/cm, head pressure 5 g/c
m was the optimal condition.

(Example 2) Based on the results of Example 1, images were printed on the following three types of paper while changing the rubber hardness of the pressure roller.

Paper name Beck smoothness (1) Lancaster bond paper 2-3 seconds (2) Xerox 4024 paper 18-30 seconds (3) Thermal transfer paper
The printing conditions for 110 to 120 seconds are as follows: (1) Platen-pressure roller pressure 10 kg/am (total pressure 230 kg) (2) Platen-head pressure 5 g/cm (total pressure 125 g) (3) Pulse period, Applied energy Others are Example 1
The results were as shown in Table 1, and a hardness of 60° to 75° was suitable. Also, from the results in the table, it can be seen that there is a certain tendency in the print quality on paper depending on the rubber hardness. In other words, for paper with low smoothness, it is better to use rubber with low hardness.In reality, it is difficult to change the roller hardness for each paper, so the pressure on the pressure roller should be made variable. It is desirable to deal with this by

Table 1 Relationship between rubber hardness and print quality [Effects of the invention] As explained above, after the transfer medium is heated by the recording head, the transferred material is immediately heated by the adjacent pressure roller whose surface is covered with an elastic material such as rubber. By pressurizing the transfer medium, we provide a thermal transfer recording device that achieves high transfer efficiency and excellent print quality even on paper with low smoothness, greatly expanding the possibilities of printout technology using thermal technology. It is something that expands.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of a thermal transfer recording apparatus according to the present invention. FIG. 2 is an explanatory diagram of the principle of the present invention, FIGS. 3 and 4 are basic configuration diagrams of a conventional thermal transfer recording apparatus, and FIG. 5 is an explanatory diagram of the principle of the conventional system. 1... Platen 2... Pressure roller 2'... Rubber-like elastic body 3... Thermal head 4... Ink film (transfer medium) 4a... Molten ink layer 4b... Solid ink layer 5... Unwinding side film roll 6... Winding side film roll 7... Pull roller (for paper) 8... Film peeling roller/guide roller 9... Paper (transferred material) 17...・Paper, film guide roller 18...Film guide roller and above Applicant Seiko Epson Co., Ltd. Agent Patent attorney Kizobe Suzuki and 1 other person Figure 1 Convex Figure 3

Claims (4)

[Claims] (1) A line thermal head is used as the recording head, and the recording head and pressure roller are arranged facing each other on the platen,
In a thermal transfer recording device having at least a structure in which the transferred object and the transfer medium pass between the platen, the recording head, and the pressure roller, the platen is made of a rigid metal body, and the pressure roller has a metal shaft with hardness. A thermal transfer recording device characterized in that the rubber-like elastic body is covered with a structure in which the rubber-like elastic body is wound at an angle of 30 degrees or more. (2) The pressing force between the platen roller and the pressure roller is
The thermal transfer recording device according to claim 1, characterized in that it is variable. (3) The thermal transfer recording apparatus according to claim 1, wherein the pressure roller applies a uniform load over the entire surface of the platen roller. (4) The thermal transfer recording apparatus according to claim 1, wherein the pressure roller and the platen roller are capable of releasing pressure.