JPH06278296A - Thermal recording apparatus - Google Patents

Abstract

PURPOSE:To provide a small-sized inexpensive thermal recording apparatus stabilizing the transfer of ink even when an intermediate transfer roller having a small outer diameter is used. CONSTITUTION:A backup roller 21 is pressed to a pressing roller 14 on the side opposite to an intermediate transfer roller 1 and the pressing roller 14 is bent toward the intermediate transfer roller 1 in a protruding state and pressed to the ink image 17 on the intermediate transfer roller 1 so as to hold recording paper 16 along with the intermediate transfer roller 1 to transfer the ink image 17 to the recording paper 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording device used for a printer, a copying machine, a facsimile or the like for recording characters and images on recording paper.

[0002]

2. Description of the Related Art In recent years, as a method for improving recording characteristics on paper having poor surface smoothness, as disclosed in JP-B-59-16932 and JP-A-62-248669,
An apparatus has been devised in which an ink image is once formed on an intermediate medium and then transferred again onto a recording sheet.

An example of the above-mentioned conventional device will be described below with reference to the drawings. FIG. 5 is a side view showing a schematic configuration of a conventional device. In FIG. 5, 28 is an intermediate transfer roller having rubber formed on its surface, and 29 is a heater for heating the intermediate transfer roller 28. Three
Reference numeral 0 is an ink sheet on which heat-meltable ink is applied and formed. A recording head 31 is configured to press the ink sheet 30 against the intermediate transfer roller 28 and selectively heat the ink sheet 30 to record the ink on the intermediate transfer roller 28. A cooler 32 is composed of a Peltier element or the like for cooling the surface of the intermediate transfer roller 28. A pressing roller 33 is configured to press the recording paper 34 against the intermediate transfer roller 28 to transfer the ink recorded on the intermediate transfer roller 28 onto the recording paper 34. 35 is a cleaner,
This is for removing the ink remaining on the intermediate transfer roller 28 after the transfer of the ink to the recording paper. The intermediate transfer roller 28 and the pressing roller 33 are supported by bearings at both ends in the axial direction.

The operation of the recording apparatus constructed as above will be described below. Intermediate transfer roller 2
The heater 8 is kept at a predetermined temperature higher than the melting point of the ink on the ink sheet 30 by the heater 29. During recording, the intermediate transfer roller 28 rotates in the direction of the arrow shown in the drawing,
Before recording by the recording head 31, the surface of the intermediate transfer roller 28 is cooled to a temperature lower than the melting point of ink by the cooler 32. Then, the ink sheet 30 is selectively heated by the recording head 31 to record the ink on the intermediate transfer roller 28. After that, the surface temperature of the intermediate transfer roller 28 returns to a temperature higher than the melting point of the ink again, so that the ink on the intermediate transfer roller 28 becomes in a molten state.
Next, the ink on the intermediate transfer roller 28 is pressed by the pressing roller 33.
It is pressed by and is transferred onto the recording paper 34. here,
The ink remaining on the intermediate transfer roller 28 after the transfer is removed and cleaned by the cleaning device 35. The above operation is continuously performed with the rotation of the intermediate transfer roller (for example, Japanese Patent Laid-Open No. 62-248669).

[0005]

However, in the above apparatus, in order to transfer the ink from the intermediate transfer roller to the recording paper well, the ink is sufficiently adhered to the irregularities on the surface of the recording paper. Required, which requires high pressure. Therefore, it is necessary to increase the pressing force of the pressing roller with respect to the intermediate transfer roller. On the other hand, in order to reduce the size of the apparatus, it is necessary to reduce the outer diameter of the intermediate transfer roller. In addition, if the outer diameter of the intermediate transfer roller becomes large, a special recording head is required and the recording head becomes expensive. Therefore, from the viewpoint of cost reduction, the outer diameter of the intermediate transfer roller is required to be small. However, when the outer diameter of the intermediate transfer roller is reduced, a bending moment is generated due to the pressing force of the pressing roller, which causes bending. Therefore, in the intermediate transfer roller,
A pressure distribution occurs between the central portion and the end portion in the axial direction, and a phenomenon occurs in which high pressure is exerted at the end portion but only low pressure is exerted at the central portion. As a result, the transfer of ink becomes unstable in the central portion. Further, if an attempt is made to increase the pressure-bonding force of the pressure roller in order to stabilize the transfer of ink, it is necessary to use a large output as a drive source for driving the pressure roller, which results in an expensive device and an apparatus. Upsizing. In addition, depending on the conditions of the apparatus, even if the pressing force of the pressing roller is increased, the bending due to the bending of the intermediate transfer roller is increased, and as a result, the pressure in the central portion hardly changes, and the transfer of ink occurs. It cannot be stabilized.

In view of the above problems, the present invention makes it possible to equalize the pressure at the transfer portion even if an intermediate transfer roller having a small outer diameter is used, and stabilizes the transfer of ink, as well as downsizing and cost reduction. It is possible to provide a device that achieves the following.

[0007]

In order to solve the above-mentioned problems, the present invention comprises an intermediate transfer roller having a surface made of flexible rubber, and an ink sheet having a row of heating elements for pressing an ink sheet against the intermediate transfer roller. A recording head that records ink on the intermediate transfer roller, a heating and heat-retaining device that heats and heats the intermediate transfer roller to a predetermined temperature at which the ink on the intermediate transfer roller causes adhesiveness, and the ink recorded on the intermediate transfer roller. And a pressing roller for pressing and transferring the recording paper to the recording paper, and pressing the pressing roller from the opposite side of the intermediate transfer roller, so that at least when the pressing roller presses the recording paper to the intermediate transfer roller, a convex shape is formed on the intermediate transfer roller side. The pressure roller is provided with a backup roller that causes bending and bending.

[0008]

According to the present invention, by pressing the pressing roller with the backup roller to cause the bending bending of the pressing roller, the pressing roller can be bent in a convex shape toward the intermediate transfer roller side. When the recording sheet is pressed against the intermediate transfer roller, it is possible to correct the bending and bending of the intermediate transfer roller and the concave shape with respect to the pressing roller, so that the pressure distribution in the axial direction can be made uniform. That is, when the pressing roller is pressed against the intermediate transfer roller, the axial distance between the rollers becomes large at the center of the roller due to the deflection of the rollers, whereas the pressing roller is previously set so that the axial distance at the central part of the roller becomes small. By flexing, the axial distance during pressing is made uniform and the pressure distribution is made uniform.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A recording apparatus according to a first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view showing a schematic configuration of a thermal recording apparatus according to a first embodiment of the present invention, FIG. 2 is a front view of the apparatus, and FIG. 3 is an explanatory view of an image forming section of the apparatus. Is. 1 and 2
Also, in FIG. 3, reference numeral 1 denotes an intermediate transfer roller having a width equal to or larger than the width of the recording paper and having an outer diameter of 24.2 m.
An intermediate transfer medium 2 made of silicone rubber having high releasability is provided on the outer peripheral surface of an iron tube having a diameter of m, an inner diameter of 19 mm, and a length of 300 mm. A known example of the silicone rubber used in the intermediate transfer medium 2 is US Pat.
836. The hardness of rubber is 20 to 70 degrees, and the thickness of rubber is 0.2 mm.
Although it is desirable to have the above values, in the present embodiment, a rubber hardness of 35 degrees and a rubber thickness of 0.4 mm are used. The intermediate transfer medium 2 is formed over a length of 220 mm,
The outer diameter of the intermediate transfer roller 1 in the portion where the intermediate transfer medium 2 is formed is 25 mm. Further, as shown in FIG. 2, both ends of the intermediate transfer roller 1 are supported by bearings 19. An infrared lamp 3 having a length corresponding to substantially the entire length of the intermediate transfer roller 1 is arranged inside the intermediate transfer roller 1, and an outer peripheral surface of the intermediate transfer roller 1 for detecting the surface temperature of the intermediate transfer medium 2. The thermistor 4 is installed in contact with the outside of a portion forming an image. A thermistor 5 for detecting the environmental temperature inside the device is installed inside the device. The infrared lamp 3, the thermistor 4, and the thermistor 5 are connected to a temperature control circuit 6, and the temperature control circuit 6 changes the set heat retention temperature of the intermediate transfer medium 2 in accordance with the temperature detected by the thermistor 5, and also the thermistor 4 Infrared lamp 3 according to the temperature detected by
Is turned on and off to keep the surface temperature of the intermediate transfer medium 2 at the preset heat retention temperature. Infrared lamp 3, thermistor 4, thermistor 5, temperature control circuit 6
And constitute the heat insulation means. Reference numeral 7 denotes an ink sheet, in which a heat-meltable ink layer 9 is uniformly applied to a base material 8 made of a plastic film having a thickness of about 3 to 9 μm. As the heat-meltable ink, a conventionally used natural or synthetic wax, a thermoplastic resin such as a polyamide resin or a polyacrylic resin is used as a binder, and carbon black or other coloring material is dispersed in the binder. . The melting point of the heat-meltable ink is preferably 50 to 160 ° C., and the ink using a binder having an uncertain melting point has a softening point of 40 to 180 ° C. according to the ring and ball method.
However, in the present embodiment, a mixture of wax and a thermoplastic resin is used as a main binder and a melting point of 6 is used.
8 ° C (melting point peak temperature by DSC) and a melt viscosity at 100 ° C of 60 poise were used, and 8 on the substrate.
μm is applied. Reference numeral 10 denotes a thermal head which serves as a thermal image forming means, which has a large number of heating element rows 11 arranged in the width direction of the intermediate transfer roller 1 and is held so as to be separable from and in contact with the intermediate transfer roller 1 with the ink sheet 7 sandwiched therebetween. Is configured to be driven by the head drive circuit 18. Both ends of the ink sheet 7 are fixed to the supply roll 12 and the winding roll 13, respectively, and are wound around the supply roll 12 and the winding roll 13. At the time of recording, in a state where the thermal head 10 presses the ink sheet 7 against the intermediate transfer roller 1, the intermediate transfer roller 1 and the ink sheet 7 are configured to be rotated or wound in the directions of the arrows by driving means (not shown). ing. A transfer pressing roller 14 is rotatably held by a lever 15, and the lever 15 is configured to press the pressing roller 14 against the intermediate transfer roller 1 by a spring. Further, as shown in FIG. 2, the pressing roller 14 has both ends supported by bearings 20 and is arranged so as to be pressed against the intermediate transfer roller 1 from the side opposite to the thermal head 10. The pressing roller 14 is made of an aluminum material and has a length between bearings of 220 mm and an outer diameter of 20 mm. Reference numeral 21 denotes a backup roller, which is supported by a bearing on the roller shaft 22 and has an outer periphery made of resin. The backup roller 21 has a width of 10 mm and an outer diameter of 14 mm, and the end portion of the roller is rounded. Therefore, it is possible to prevent the surface of the pressing roller 14 from being scratched by the edge of the backup roller 21 when the pressing roller 14 is pressed. Further, the backup roller 21 is configured to press the pressing roller 14 at the central portion in the axial direction from the side opposite to the intermediate transfer roller 1. Roller shaft 22 has an outer diameter of 8 m
roller shaft 2
At both ends of 2, the axial distance between the end of the roller shaft 22 and the end of the pressing roller 14 is the backup roller 21 and the pressing roller 14.
Lever 15 at a position that is 3 mm shorter than the shaft distance of
It is screwed to. Therefore, as shown in FIG. 2, the roller shaft 22 is fixed in a bent state. At this time, the pressing roller 14 is bent in a convex shape with respect to the intermediate transfer roller 1 by the pressing force of the backup roller 21. The pressing roller 14 is normally held at a position away from the intermediate transfer roller 1 by a drive mechanism (not shown), and when the recording paper 16 is inserted at the time of transfer, the intermediate transfer in which the ink image 17 is formed with the recording paper 16 sandwiched therebetween is formed. While the recording sheet 16 is pressed against the roller 1, the recording sheet 16 is sequentially sent out in the direction of the arrow as the intermediate transfer roller 1 rotates. At this time, the pressing force of the pressing roller 14 against the intermediate transfer roller 1 is 30 k as a whole.
It is g.

Next, the operation of this embodiment will be described.
First, when the power source of the apparatus is turned on, the thermistor 5 measures the environmental temperature, and the temperature control circuit 6 sets the target value of the heating temperature of the intermediate transfer medium 2. Here, the temperature control circuit 6 controls the infrared lamp 3 to be turned on and off while the temperature of the intermediate transfer medium 2 is being detected by the thermistor 4 so as to reach a target heating temperature. Regarding the heat retention temperature of the surface of the intermediate transfer medium 2, the cohesive strength of the ink at this temperature is larger than the adhesive force between the ink and the intermediate transfer medium 2, and the ink on the intermediate transfer medium is softened so that the recording paper is It is set so that it can be attached to. Although an appropriate value for this heat retention temperature varies depending on the characteristics of the ink used, the material of the surface of the intermediate transfer medium 2, the recording conditions, etc., in this embodiment, it is set to 70 ° C. when the environmental temperature is 20 ° C. ing. Further, the set value of the intermediate transfer medium temperature is set to be high when the environmental temperature is low, and the set value of the intermediate transfer medium temperature is set to be low when the environmental temperature is high. The medium temperature is set to 75 ° C., and the intermediate transfer medium temperature is set to 65 ° C. when the environmental temperature is 40 ° C.

Then, when a recording command is input, the thermal head 10 presses the intermediate transfer roller 1 with the ink sheet 7 sandwiched therebetween, and at the same time, the intermediate transfer roller 1 and the ink sheet 7 start moving in the arrow directions. When print signals are sequentially input to the heating element array 11 in this state, the ink in contact with the heated portion is melted and adheres to the intermediate transfer medium 2 due to an adhesive force. Then, as shown in FIG. 3, the ink sheet 7 is immediately separated from the intermediate transfer roller 1 and wound up by the winding roll 13. A portion that is not heated by the thermal head 10 comes into contact with the intermediate transfer medium 2 and is heated and softened. However, since the intermediate transfer medium 2 is made of silicone rubber having high releasability, the adhesive force to the ink is weak. . Further, at the heat-retaining temperature of the intermediate transfer medium 2, the cohesive strength of the ink is higher than the adhesive force, and the adhesive force between the ink and the base material 8 is higher than the adhesive force between the ink and the intermediate transfer medium 2. Since it is high, the ink does not transfer to the intermediate transfer medium 2. On the other hand, the ink heated and melted by the thermal head 10 has a sufficiently lower viscosity than the other parts, and the cohesive strength of the ink causes the adhesive force between the ink and the base material 8 and the ink and the intermediate transfer medium 2. The ink is cohesively destroyed in the layer and transferred as an ink image 17 to the surface of the intermediate transfer medium 2 because the ink is less than the adhesive force between them. By the operation as described above, the image formation of the ink image 17 on the intermediate transfer medium 2 is successively performed. Next, the ink image 17 formed on the surface of the intermediate transfer medium 2 is carried to a position facing the pressing roller 14 by the rotation of the intermediate transfer roller 1. Here, the recording paper 16 is fed, the pressing roller 14 is pressed against the intermediate transfer roller 1 with the recording paper 16 sandwiched therebetween, and the recording paper 16 is fed sequentially as the intermediate transfer roller 1 rotates. At this time, the pressing roller 14 is the backup roller 2
It is pressed by the intermediate transfer roller 1 while being pressed by 1. At this time, the ink image 17 on the surface of the intermediate transfer medium 2 becomes the same temperature as the heat retention temperature of the intermediate transfer medium 2 and softens to have an adhesive force to the recording paper 16, and this adhesive force is intermediate. Since the ink image 17 is configured to have a larger cohesive strength than the transfer medium 2 at the heat-retaining temperature and an adhesive force between the intermediate transfer medium and the ink, the ink image 17 does not undergo cohesive failure between the ink layers and is intermediately transferred. It is separated from the interface of the medium 2 and transferred onto the recording paper 16. At this time, since the intermediate transfer medium 2 is made of flexible silicone rubber, the flexibility of the ink image 1
7 can be closely adhered to the irregularities on the surface of the recording paper 16. As a result, good transferability can be obtained even on paper with low surface smoothness and large unevenness. At this time, the intermediate transfer roller 1 bends in a concave shape with respect to the pressing roller 14 due to the pressing of the pressing roller 14, but the backup roller 21 previously bends the pressing roller 14 in a convex shape with respect to the intermediate transfer roller. Therefore, when the pressing roller 14 is pressed, the axial distance between both rollers can be made substantially uniform at any position of the rollers, and the pressure distribution between the rollers can be made uniform. Further, the backup roller 21 is pressed against the pressing roller 14 by the elastic force due to the bending of the roller shaft 22 and is fixed in a preloaded state, so that the number of parts is small and the structure is inexpensive and simple. Is something that can be.

In order to make the pressure distribution uniform, it is conceivable to press the backup roller against the intermediate transfer roller from the side opposite to the pressing roller. In this case, the backup roller is placed on the surface of the intermediate transfer roller. It will come into direct contact, which may affect the functional deterioration of the intermediate transfer roller. In addition, since the surface of the intermediate transfer roller is made of a flexible rubber material, if the backup roller is left in pressure contact with the intermediate transfer roller when the apparatus is stopped, the rubber material is deformed and distorted, which causes a defect in recording transfer. Will occur. For this reason, the backup roller has to be configured to be pressure-bonded only when the intermediate transfer roller is rotating, resulting in a complicated configuration. Further, the backup roller, the pressing roller, and the thermal head are pressed against the intermediate transfer roller, so that the outer diameter of the intermediate transfer roller must be increased, and the apparatus becomes large. .
On the other hand, according to the configuration of the present invention, since the backup roller is pressed against the pressing roller,
The backup roller does not directly contact the intermediate transfer roller, and the pressure can be made uniform without affecting the intermediate transfer roller. Further, it is possible to provide a structure in which the backup roller is constantly pressed against the pressing roller, and it is possible to supply an inexpensive device with a simple structure. Further, it is not necessary to increase the outer diameter of the intermediate transfer roller, and a small device can be configured.

As described above, according to the present invention, the backup roller is pressed against the pressing roller from the side opposite to the intermediate transfer roller to cause the bending bending of the pressing roller. The distribution can be made uniform, and the transfer of the ink onto the recording paper can be stabilized. Further, it is possible to supply a small-sized and inexpensive device with a simple structure.

Next, a second embodiment of the present invention will be described. FIG. 4 is a front view showing a schematic configuration of the thermal recording apparatus of the second embodiment of the present invention. The configuration of the device is almost the same as that of the device of the first embodiment, but in this embodiment,
The backup roller 21 is configured to have the same length as the pressing roller 14 and has a medium-thick shape in which the central portion is thicker than the end portions, and both end portions are supported by bearings 23 so that the backup roller 21 can rotate. The point is different. Also, in the first embodiment, the backup roller 2
While the roller shaft serving as the first support shaft is bent to apply the pressing force, the backup roller 21 itself is bent to apply the pressing force in this embodiment. Also in this embodiment, the same effect as that of the first embodiment can be exhibited.

Further, in the second embodiment, the backup roller may be formed in a straight roller shape, and the backup roller may be attached so as to be inclined so as to intersect the pressing roller at the central portion of the roller. In this case, it is possible to bend the pressing roller by applying a pressing force to the central portion of the pressing roller by mounting the rollers so as to cross each other. Even in such a configuration, the same effect as that of the above-described embodiment can be exhibited.

[0017]

As described above, according to the thermal recording apparatus of the present invention, the backup roller is pressed against the pressing roller from the side opposite to the intermediate transfer roller, and the pressing roller is bent in a convex shape with respect to the intermediate transfer roller. By doing so, the deflection of the intermediate transfer roller when the recording sheet is pressed against the intermediate transfer roller by the pressing roller can be corrected to make the pressure distribution uniform in the axial direction and stabilize the transfer. It is possible. Further, the diameter of the intermediate transfer roller can be reduced, and a small and inexpensive device can be supplied.

[Brief description of drawings]

FIG. 1 is a side view showing a schematic configuration of a thermal recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a front view of the same device.

FIG. 3 is a diagram showing an ink image forming process in the apparatus.

FIG. 4 is a front view showing a schematic configuration of a thermal recording apparatus according to a second embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a conventional recording device.

[Explanation of symbols]

 1 Intermediate Transfer Roller 2 Intermediate Transfer Medium 3 Infrared Lamp 7 Ink Sheet 10 Thermal Head 14 Pressing Roller 16 Recording Paper 17 Ink Image 18 Head Drive Circuit 21 Backup Roller 22 Roller Axis

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location 9113-2C B41J 29/00 H (72) Inventor Yoshihisa Fujimori 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Sangyo Co., Ltd. (72) Inventor Nobuyoshi Taguchi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. An intermediate transfer roller whose surface is made of flexible rubber, and an ink sheet coated with a heat-meltable ink,
A recording head, which has a row of heating elements, presses the ink sheet against the intermediate transfer roller and selectively heats the ink sheet to record ink on the intermediate transfer roller, and ink on the intermediate transfer roller Heating and heat retaining means for heating and retaining the intermediate transfer roller to a predetermined temperature that causes adhesion, a pressing roller for pressing and transferring the ink recorded on the intermediate transfer roller onto a recording sheet, and a side opposite to the intermediate transfer roller. The pressure roller to press the pressure roller, and at least when the pressure roller presses the recording sheet to the intermediate transfer roller, the backup roller bends the intermediate transfer roller so that the pressure roller has a convex shape when viewed from the front of the pressure roller. Thermal recording device equipped with rollers. 2. A structure in which a pressing force against a pressing roller is generated by an elastic force due to bending bending of a backup roller itself or a support shaft of the backup roller, and the backup roller is constantly pressed against the pressing roller. The thermal recording apparatus according to claim 1, wherein the thermal recording apparatus is a thermal recording apparatus.