JPH05293983A - Thermal recorder - Google Patents

Abstract

PURPOSE:To compensate for a difference in direction between the curvatures of the generating lines of an intermediate drum, to make the diameter of the intermediate drum small, and to miniaturize a device, by carrying out thermal recording only when a pressure roller is being firmly pressed against the intermediate drum. CONSTITUTION:The title recorder is provided with: an intermediate drum 1; a pressure roller 7 which is firmly pressed against the intermediate drum 1; and a thermal recording head 6 which carries out thermal recording on the intermediate drum 1. A hot-melt ink image 9 is formed on the intermediate drum 1 by means of the thermal recording head 6. Thereafter a recording sheet 8 is passed between the intermediate drum 1 and the pressure roller 7, thereby transferring the ink image 9 on the intermediate drum to the recording sheet 8. Here, the thermal recording head 6 carries out image formation only when the pressure roller 7 is being firmly pressed against the intermediate drum 1. Further, the thermal recording head can also abut on the intermediate drum by being made to curve according to a warp in the intermediate drum caused when the pressure roller 7 is firmly pressed against the intermediate drum 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording apparatus for recording an image on an intermediate drum by heat-sensitive recording using a heat-melting ink and then transferring the image onto a recording sheet.

[0002]

2. Description of the Related Art In recent years, heat-sensitive recording apparatuses using heat-meltable ink have been popularized from low-priced fields to high-performance products by taking advantage of the simple apparatus configuration and maintenance-free. A major problem of this thermal recording apparatus is the improvement of the recording characteristics of plain paper, and various improvements have been made so far.

An example of the above-described conventional thermal recording apparatus will be described below with reference to the drawings.

FIG. 6 shows the recording principle of a conventional thermal recording apparatus. In FIG. 6, 51 is an intermediate drum, and a silicone rubber 52 is provided on the outer periphery of an aluminum tube 54. An infrared lamp 55 is disposed inside the intermediate drum 51 and is configured to heat the intermediate drum 51 to a predetermined temperature. Reference numeral 56 is a thermal head, and 53 is a sheet-like ink sheet coated with a heat-meltable ink. Reference numeral 57 is a pressure contact roller, which is a spring 61 via a lever 60.
The recording paper 58 is pressed against the intermediate drum 51 by the urging force of. 59 is a thermal head 56
It is an ink image formed on the intermediate drum 51 by.

The operation of the thermal recording apparatus having the above structure will be described below.

Before performing the recording operation, the intermediate drum 51 is heated and kept warm by the infrared lamp 55 until the surface temperature of the silicone rubber layer 52 reaches a predetermined temperature. In this state, the ink sheet 53 is sandwiched between the thermal head 56 and the intermediate drum 51, and at the same time, the intermediate drum 51 is rotated in the direction of the arrow to wind the ink sheet 53 in the direction of the arrow. Then, according to the image information, the thermal head 56
The heating element is heated and the ink sheet 53 is immediately separated. In this way, first, the ink image 59 is formed on the intermediate drum 51. After that, when the pressing roller 57 presses the recording paper 58 against the intermediate drum 51, the ink image 59 is transferred to the recording paper 58, and the recording of the image is completed. The predetermined temperature of the silicone rubber layer 52 in this case means that the ink image 59 is sufficiently fixed by the pressure of the pressure roller 57, and the cohesive force of the ink image 59 is the adhesive force between the ink image 59 and the silicone rubber layer 52. The temperature is higher than that (for example, Japanese Patent Laid-Open No. 3-227254).

[0007]

However, in the above construction, in order to sufficiently fix the ink image 59 on the recording paper 58, the pressure contact roller 57 is usually 30 kgf to 50 kgf when the A4 paper is vertically fed. It is necessary to crimp. By using a color sheet in which multicolor inks are applied to the ink sheet 53 in a frame-sequential manner, the peripheral length of the intermediate drum 51 is adjusted to the length of the recording paper 58, and the multicolor ink images 59 are superimposed on the intermediate drum 51. In the case of the method of transferring to the recording paper 58 after forming the image, the diameter of the intermediate drum 51 becomes large, so that there is no problem even with this configuration. However, when recording in single color,
Alternatively, when the recording paper 58 is reciprocated and transferred to the recording paper 58 for each color, the transfer can be performed to the recording paper 58 immediately after the image formation on the intermediate drum 51. Although it is possible to reduce the size of
If the diameter of the intermediate drum 51 is reduced, the strength becomes smaller, and the intermediate drum 51 is bent by the pressure contact force of the pressure contact roller 57,
Since the contact pressure of the thermal head becomes non-uniform in the longitudinal direction, there is a problem in that image density and line width are uneven.

In view of the above problems, the present invention has an intermediate drum 51.
The present invention provides a thermal recording apparatus in which the contact pressure of the thermal head 56 becomes uniform even if the diameter of the recording head is reduced, and recording unevenness in the longitudinal direction can be eliminated.

[0009]

In order to solve the above-mentioned problems, a thermal recording apparatus of the present invention comprises an intermediate drum, a pressure roller which is in pressure contact with the intermediate drum, and a thermal recording head which performs thermal recording on the intermediate drum. The thermal recording head forms an image of heat-melt ink on the intermediate drum, and then the recording paper is passed between the intermediate drum and the pressure roller to transfer the intermediate drum-shaped ink image to the recording paper. In the thermal recording apparatus, the thermal recording head forms an image only while the pressure roller is in pressure contact with the intermediate drum.

Further, the heat-sensitive recording apparatus of the present invention has a structure in which the thermal recording head is curved and brought into contact with the intermediate drum in accordance with the deflection of the intermediate drum when the pressure roller is brought into pressure contact with the intermediate drum. is there.

Further, the heat-sensitive recording apparatus of the present invention has a structure in which the heating elements of the thermal recording head are arranged in accordance with the deflection of the intermediate drum when the pressure roller is brought into pressure contact with the intermediate drum.

Further, the heat-sensitive recording apparatus of the present invention has a structure in which the heating element of the thermal recording head is caused to generate heat by shifting the timing according to the deflection of the intermediate drum when the pressure roller is brought into pressure contact with the intermediate drum. It is a thing.

[0013]

According to the present invention, with the above-described structure, the image formation on the intermediate drum by the thermal recording head is always performed while the pressure roller is in pressure contact with the intermediate drum. When the diameter of the intermediate drum is reduced, the intermediate drum bends and returns due to pressure contact and separation of the pressure roller, but according to the present invention, the state of the intermediate drum and the thermal recording head during image formation is always constant. Therefore, by optimally setting the image forming condition for the intermediate drum in a deflected state, it is possible to suppress the adverse effect due to the pressure contact of the pressure roller.

Further, according to the present invention, since the thermal recording head is curved in accordance with the pre-expected deflection of the intermediate drum at the abutting position of the thermal recording head, the present invention makes it possible to bend the intermediate recording drum. The pressing force becomes constant, and good image formation becomes possible.

Further, at the abutting position of the pressure contact roller and at the position opposite thereto, the generatrix of the intermediate drum does not have a curvature in the circumferential direction, but at other positions, it has a curvature in the circumferential direction. According to the present invention, by arranging the heating element of the thermal recording head in accordance with the deflection of the intermediate drum which is expected in advance at the contact position of the thermal recording head, the present invention provides:
It is possible to compensate the dot shift in the sub-scanning direction caused by the circumferential deflection of the generatrix of the intermediate drum at the contact position of the thermal recording head.

Further, according to the present invention, since the heating element of the thermal recording head is caused to generate heat by shifting the timing in correspondence with the deviation of the generating line in the circumferential direction of the generating line due to the bending of the intermediate drum, the present invention can be applied at the pressing position of the pressing roller. It is possible to compensate the dot shift in the sub-scanning direction.

[0017]

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

FIG. 1 is a schematic configuration diagram of a thermal recording apparatus according to the first embodiment of the present invention. In FIG. 1, 1 is an intermediate drum, and a silicone rubber 2 is provided on the outer circumference of an aluminum tube 4.
Is provided. A halogen lamp 5 is disposed inside the intermediate drum 1 and is configured to heat the intermediate drum 1 to a predetermined temperature. 6 is a thermal head, 3
Is a sheet-shaped ink sheet coated with a heat-meltable ink. The thermal head 6 is connected to the spring 13 via the lever 12.
The intermediate drum 1 with the ink sheet 3 sandwiched by the urging force of
Is pressed by. A pressure contact roller 7 is configured to press the recording sheet 8 against the intermediate drum 1 by the urging force of the spring 11 via the lever 10. 9 is a thermal head 6
2 is an ink image formed on the intermediate drum 1.

The operation of the thermal recording apparatus having the above structure will be described below with reference to FIGS. 1, 2 and 3.

In the standby state, the temperature control means (not shown) controls the blinking of the halogen lamp 5 to keep the silicone rubber layer 2 of the intermediate drum 1 at a predetermined temperature.
At this time, the thermal head 6 and the pressure contact roller 7 are brought into contact with and separated from the intermediate drum 1 by a contacting means (not shown).

In the recording operation, first, the intermediate drum 1
Rotates in the direction of the arrow, the pressing roller separating / contacting means is released, and the pressing roller 7 is pressed against the intermediate drum 1. Next, the thermal head separating / contacting means is released, the thermal head 6 is pressed against the intermediate drum 1 with the ink sheet 3 sandwiched therebetween, and the ink sheet 3 is wound in the direction of the arrow. The thermal head 6 generates heat from the heating element according to the image information, and the ink sheet 3
The melted ink forms an image and is formed in an intermediate drum shape. The recording paper 8 is sent to the pressure contact portion between the pressure contact roller 7 and the intermediate drum 1 at the timing of the beginning of the image, and the ink image 9 is transferred.

FIG. 2 is a timing chart during the recording operation, showing the timing of the pressure contact of the pressure contact roller 7, the pressing of the thermal head 6, and the recording enable signal of the thermal head 6. In Figure 2, at time T ₁ disjunction means of the press roller 7 is released, the thermal head 6 to time T _2,
The connecting / disconnecting means of is released. At time T ₃ , a recording enable signal is issued and the thermal head 6 starts image formation. Time t from the time T ₁ until T _{3 1} is disjunction means pressing roller 7 is intermediate drum 1 since the the release of the pressure contact roller 7
It is the time until the intermediate drum 1 is completely pressed and pressed, and the intermediate drum 1 is flexed and stabilized by the pressing force. At the end of recording, the recording enable signal is turned off at time T ₄ , the separating / contacting means of the thermal head 6 is activated at time T ₅ , and further the separating / contacting means of the pressure contact roller 7 is activated at time T ₆ . The time t ₂ from time T ₄ to T _{6 is} the time until the end of the ink image 9 formed on the intermediate drum 1 reaches the pressure contact portion between the pressure contact roller 7 and the intermediate drum 1. That is, the thermal head 6
The image formation is performed only while the pressure contact roller 7 is in pressure contact with the intermediate drum 1 and the intermediate drum 1 is flexed.

FIG. 3 is a view of the thermal head 6 as seen from the direction of arrow A. In FIG. 3, the levers 12 are fixed to both ends of the thermal head 6. Reference numeral 14 denotes a fulcrum shaft of the lever 12, which is fixed to the substrate shown by hatching. During the recording operation, the intermediate drum 1 is bent by the pressure contact force of the pressure contact roller 7. For example, when the press contact roller 7 is pressed against the aluminum intermediate drum 1 having an outer diameter of 30 mm and a wall thickness of 5 mm with a press contact force of 30 kgf, the maximum deflection amount at the center is about 50 μm. Become. In the present embodiment, as shown in FIG. 3, the thermal head 6 is supported at both ends thereof, so that the flexure of the intermediate drum 1 is absorbed by the elastic deformation of the thermal head 6 to alleviate the uneven pressing force.

As described above, according to this embodiment, the image formation by the thermal head 6 is performed only while the pressure contact roller 7 is in pressure contact with the intermediate drum 1, and the thermal head 6 is supported at both ends thereof. With such a configuration, uneven pressing of the thermal head 6 due to bending of the intermediate drum 1 by the pressure contact roller 7 can be alleviated, and the diameter of the intermediate drum 1 can be reduced.

A second embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a schematic configuration diagram of a thermal recording apparatus showing a second embodiment of the present invention. The difference from the configuration of FIG. 1 is that the contact position of the thermal head 6 is set to the pressure roller 7
Is a point provided at a position 90 degrees away from the position where it is pressed against the intermediate drum 1.

The operation of the thermal recording apparatus having the above structure will be described below with reference to FIGS. 4 and 5.

During the recording operation, the intermediate drum 1 is bent by the pressure contact force of the pressure roller 7 as in the first embodiment. In this embodiment, since the thermal head 6 is in contact with the contact position of the pressure roller 7 at a position of 90 degrees, unevenness of the pressing force due to the bending of the intermediate drum 1 is almost eliminated. For example, even if the maximum amount of deflection of the intermediate drum 1 is 100 μm, the waviness in the axial direction is only 1 μm or less at the position of 90 degrees.

FIG. 5 is a plan view of the thermal head 6 in the second embodiment. In FIG. 5, reference numeral 15 denotes an array of heating elements formed on the substrate of the thermal head 6.
At the abutting position of the thermal head 6, the generatrix of the intermediate drum 1 has a curvature in the circumferential direction due to the deflection of the intermediate drum 1, but at the abutting position of the pressure contact roller 7, it becomes the radial direction and becomes linear in the circumferential direction. Becomes Therefore, the array of heating elements 1
By setting the curvature of 5 to match the deflection of the intermediate drum 1, the deviation of dots in the main scanning direction is corrected.

As described above, according to this embodiment, the contact position of the thermal head 6 is provided at a position 90 degrees away from the position where the pressure contact roller 7 is pressed against the intermediate drum 1, and Since the array 15 has a curvature adapted to the flexure of the intermediate drum 1, it is possible to eliminate the unevenness of the pressing force of the thermal head 6 due to the flexure of the intermediate drum 1 and to correct the dot deviation in the main scanning direction. The diameter of the intermediate drum 1 can be reduced, and a small thermal recording device can be realized.

In the first embodiment, the thermal head 6 supports both ends of the thermal head 6 to support the intermediate drum 1.
Although it is supposed to follow the flexure of the intermediate drum 1, the thermal head 6 may be forcibly adjusted to the flexure of the intermediate drum 1 by fixing the thermal head 6 to a supporting member having a curvature matching the flexure curve of the intermediate drum 1. Further, the heating elements of the thermal head 6 may be arranged on the surface having a curvature that matches the deflection curve of the intermediate drum 1 in the contact direction.

In the second embodiment, the arrangement of the heating elements of the thermal head 6 is set to have a curvature that matches the deflection of the intermediate drum 1, so that the dot deviation in the main scanning direction is corrected. The array 15 may be linear, and the order of time division for each block of the heating element may be corrected so as to be directed from the outer sides toward the center. Further, the contact position of the thermal head 6 is upstream of the contact position of the pressure contact roller 7, but the contact position of the thermal head 6 may be downstream of the contact position of the pressure contact roller 7, and in that case. It goes without saying that the direction of time division of the heating element may be set to the outside from the center.

In the first and second embodiments, the intermediate drum 1 is kept at a predetermined temperature by the halogen lamp 5, but this temperature should be set according to the characteristics of the ink used. Needless to say, some of them exhibit good fixing properties even at room temperature, and in that case, it is not necessary to keep them warm. Further, the heat retaining means is not limited to the internal halogen lamp 5, but may be a planar heater or an external heating method.

Also, in the timing chart of the recording operation,
Kick time T₁, T₂, T_Five, T₆Is T ₁<T₂, T_Five<T₆When
However, if there is no obstacle to running the ink sheet 3,
This relationship is not limited to this.

Further, the recording means for the intermediate drum 1 is the thermal head 6, but the recording method may use other means, for example, a resistance sheet and an electric recording head. Further, the surface layer of the intermediate drum 1 is the silicone rubber layer 2, but this material should be selected according to the characteristics of the ink, and any material can be used as long as it is good in image formation and transfer.

[0035]

As described above, according to the present invention, the image formation by the thermal recording head is performed only when the pressing roller is completely pressed against the intermediate drum, and the image due to the deformation of the intermediate drum is formed. Since the change in the forming conditions can be eliminated, the diameter of the intermediate drum can be reduced, and a small thermal recording device can be realized.

Further, according to the present invention, since the thermal recording head is configured to be curved in accordance with the flexure of the intermediate drum, stable image formation can be performed on the flexed intermediate drum, so that the diameter of the intermediate drum can be reduced. It becomes possible to
A small thermal recording device can be realized.

Further, according to the present invention, by arranging the heating elements of the thermal recording head according to the deflection curve of the intermediate drum, it is possible to compensate for the difference in the direction of curvature of the generatrix of the intermediate drum during image formation and transfer. Since it is possible to reduce the diameter of the intermediate drum, a small thermal recording device can be realized.

Further, according to the present invention, the heating element of the thermal recording head is caused to generate heat by shifting the timing according to the deflection of the intermediate drum, so that the direction of curvature of the generatrix of the intermediate drum at the time of image formation and transfer is different. Can be compensated for
The diameter of the intermediate drum can be reduced, and a small thermal recording device can be realized.

[Brief description of drawings]

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

FIG. 2 is a timing chart during recording operation of the thermal recording apparatus according to the first embodiment of the present invention.

FIG. 3 is a view of the thermal head in FIG.

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

5 is a plan view of the thermal head in FIG.

FIG. 6 is a schematic configuration diagram of a heat-sensitive recording device in the related art.

[Explanation of symbols]

 1 Intermediate Drum 2 Silicone Rubber Layer 3 Ink Sheet 4 Aluminum Tube 5 Halogen Lamp 6 Thermal Head 7 Pressure Contact Roller 8 Recording Paper 9 Ink Image

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihisa Fujimori 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Soichiro Mima, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Nobuyoshi Taguchi 1006, Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. An intermediate drum, a pressure contact roller that is in pressure contact with the intermediate drum, and a thermal recording head for performing thermal recording on the intermediate drum. The thermal recording head records an image on the intermediate drum. In a heat-sensitive recording apparatus that transfers the image onto the recording sheet by passing the recording sheet through a pressure contact portion between the intermediate drum and the pressure contact roller, while the pressure contact roller is in pressure contact with the intermediate drum. A thermal recording apparatus, wherein recording is performed only by the thermal recording head. 2. The heat-sensitive recording apparatus according to claim 1, wherein the thermal recording head is curved and abuts against the intermediate drum in accordance with the deflection of the intermediate drum when the pressure roller is pressed against the intermediate drum. .. 3. The heat-sensitive recording apparatus according to claim 1, wherein the heating elements of the thermal recording head are arranged in accordance with the deflection of the intermediate drum when the pressure roller is pressed against the intermediate drum. 4. The heat-sensitive recording apparatus according to claim 1, wherein the heating element of the thermal recording head is configured to generate heat by shifting the timing according to the deflection of the intermediate drum when the pressure roller is pressed against the intermediate drum. .. 5. The heat-sensitive recording apparatus according to claim 1, wherein the surface layer of the intermediate drum is made of silicone rubber.