JPH0852886A - Thermal transfer printer - Google Patents

Abstract

PURPOSE:To provide a thermal transfer printer easily controlling primary recording image forming temp. and re-transfer temp. to obtain an image having uniform density and dying obviate the cleaning mechanism of an intermediate transfer roller to reduce the cost for parts. CONSTITUTION:An intermediate transfer roller 3 is heated by a heater 4 so that the surface temp. thereof on a side forming a primary recording image is made higher than that on a re-transfer side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention selectively heats an ink layer of an ink ribbon by a thermal head and transfers it to an intermediate transfer roller to form a primary recording image, and the primary recording image is retransferred to a printing paper. The present invention relates to an intermediate transfer type thermal transfer printer.

[0002]

2. Description of the Related Art Conventionally, a thermal transfer printer has been widely used in which a thermal head is pressed against a platen via a printing paper and an ink ribbon to perform recording. In such a thermal transfer printer, the surface of bond paper or the like is used. When recording on a paper having a rough surface, it is necessary to press the thermal head against the paper on the platen with a strong pressing force, but the pressing force of the thermal head is limited due to its precise structure. Then, the heat generated by the thermal head selectively melts the ink layer of the ink ribbon and transfers it to the intermediate transfer body to form a primary recording image on the intermediate transfer body, and then the primary recording image on the intermediate transfer body. There is used an intermediate transfer type thermal transfer printer which performs recording by re-transferring to the printing paper which is pressed by a strong pressing force of a pressure roller.

FIG. 4 is a partial structural sectional view of a conventional intermediate transfer type thermal transfer printer. First, the intermediate transfer roller 3 in which the surface of a metal having a cylindrical cross section is covered with a rubber material
Are rotatably arranged, and the intermediate transfer roller 3
On the other hand, the thermal head 1 is arranged via the ink ribbon 2 so as to be able to move forward and backward in the directions of arrows A1 and A2. The intermediate transfer roller 3 also functions as a platen roller, and the hollow structure thereof has a temperature at which the ink layer 10 of the ink ribbon 2 can be transferred to the intermediate transfer roller 3 as a primary recording image. A heater 4 is provided for heating the recording image to a set temperature at which the recording image can be retransferred to the printing paper 6. The ink layer 10 of the ink ribbon 2 is written as a primary recording image on the intermediate transfer roller 3 by the selective heat generation of the thermal head 1, and is conveyed in the direction of arrow C as the intermediate transfer roller 3 rotates. It On the other hand, the ink ribbon 2 is conveyed in the direction of arrow D by frictional driving with the intermediate transfer roller 3, and is wound onto the winding-side bobbin 11 by a driving source (not shown). On the other hand, a pressure roller 5 which is capable of advancing and retracting in the directions of arrows B1 and B2 with respect to the intermediate transfer roller 3 via the printing paper 6 is provided. The pressure roller 5 moves in the direction of arrow B1 in order to retransfer the primary recording image onto the printing paper 6, and presses the printing paper 6 against the intermediate transfer roller 3 heated to a predetermined temperature. Is. The printing paper 6 thus retransferred is conveyed in the direction of arrow E.

In the case of such a thermal transfer printer, at the time of forming the above-mentioned primary recording image and at the time of retransfer, the surface of the intermediate transfer roller 3 is raised by the heating of the built-in heater 4 and each process is performed. It is designed to proceed smoothly.

[0005]

However, in reality, the optimum surface temperature of the intermediate transfer roller 3 for the progress of each process is such that the ink layer 10 is formed on the intermediate transfer roller 3 as a primary recording image. There is a difference between the case where this is performed and the case where this primary recording image is retransferred to the printing paper 6.

On the other hand, since the heater 4 built in the intermediate transfer roller 3 of the conventional thermal transfer printer is arranged substantially at the center of the intermediate transfer roller 3 as shown in FIG. It was impossible to heat the temperature for forming such a primary recording image and the temperature for re-transferring onto the printing paper 6 so as to be the respective optimum temperatures.

Therefore, in actuality, the temperature has been set to a proper temperature while considering a certain allowable range with respect to the optimum temperature of both temperatures. For this reason, the surface temperature of the intermediate transfer roller 3 fluctuates up and down with respect to the set temperature, and when the temperature becomes lower than the set temperature, retransfer is not properly performed and the intermediate transfer roller 3 does not retransfer. When the ink layer 10 remains, or on the contrary, the temperature becomes higher than the set temperature, the ink layer 10 melts on the intermediate transfer roller 3,
The primary recording image was not formed well, and the print density on the print paper 6 became uneven.

As means for avoiding the problem of ink remaining on the intermediate transfer roller 3, for example, Japanese Patent Laid-Open No. 62-62
Various cleaning mechanisms such as those disclosed in Japanese Patent No. 248669 are provided to treat stains on the residual ink, but there has been a problem that the cost of parts and the like for that purpose becomes expensive.

Therefore, the present invention overcomes the problems of the prior art described above, and can easily control the formation temperature and retransfer temperature of the primary recording image to obtain an image of uniform density and the intermediate transfer. An object of the present invention is to provide a thermal transfer printer that can reduce the cost of parts by eliminating the roller cleaning mechanism.

[0010]

In order to achieve the above object, in the thermal transfer printer according to claim 1 of the present invention, the thermal head is pressed into contact with the intermediate transfer roller composed of a rotating body having a built-in heater for selection. Is heated to form a primary recording image of the ink layer of the ink ribbon on the intermediate transfer roller, and the primary recording image is heated on the intermediate transfer roller and pressed by a pressure roller to form a printing paper. A thermal transfer printer for retransfer is characterized in that the intermediate transfer roller is heated by the heater so that the surface temperature of the intermediate transfer roller is higher on the retransfer side than on the side on which the primary recording image is formed. There is.

Further, a thermal transfer printer according to a second aspect of the present invention is characterized in that, in the first aspect, the heater is arranged at a position closer to the side of retransfer than the center of the intermediate transfer roller.

A thermal transfer printer according to a third aspect of the present invention is characterized in that, in the first and second aspects, a fixing tool for fixing the printing paper is provided on the outer circumference of the pressure roller.

[0013]

According to the thermal transfer printer of the present invention, when the ink layer of the ink ribbon is formed as a primary recording image on the intermediate transfer roller by selective heating by the thermal head,
Since the surface temperature of the intermediate transfer roller is lower than the temperature of the portion re-transferred by the heater and the temperature is maintained at a temperature suitable for forming the primary recording image, the primary recording image can be reliably formed. On the other hand, when the primary recording image is re-transferred onto the printing paper, the surface temperature of the intermediate transfer roller is higher than that of the primary recording image forming portion by the heater, and the intermediate transfer roller is heated and maintained at an appropriate temperature for re-transfer. Therefore, stable retransfer is possible.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in FIGS. It should be noted that the same components as those of the conventional one described above are denoted by the same reference numerals in the drawings, and description thereof is omitted.

FIG. 1 is a partial structural sectional view of a first embodiment of a thermal transfer printer of the present invention. First, the surface of a metal having a cylindrical cross section is coated with a rubber material, and the surface of the rubber is covered. Intermediate transfer roller 3 coated with an intermediate transfer member
Are rotatably arranged by a drive source (not shown).
From the experimental results, it is optimal that the rubber thickness is 1 to 2 mm, and the coating thickness is 10 to 500 μm.
m is suitable, and more preferably 100 to 200.
It was in the range of μm. The intermediate transfer roller 3 also functions as a platen roller, and a heater 4 such as a halogen lamp for heating the intermediate transfer roller 3 is provided inside the intermediate transfer roller 3 rather than the center position of the intermediate transfer roller 3, which will be described later. It is arranged at a position closer to the 5 side. The heater 4 heats the intermediate transfer roller 3 and raises the surface temperature thereof, whereby the thermal head 1
Thus, the ink layer 10 of the ink ribbon 2 can be reliably formed on the intermediate transfer roller 3 as a primary recording image, and the primary recording image can be stably retransferred onto the printing paper 6. Then, the thermistor 7 for detecting the surface temperature of the intermediate transfer roller 3 is
It is arranged so as to contact with.

A thermal head 1 having a width larger than the width of the printing paper 6 is arranged on the intermediate transfer roller 3 via the ink ribbon 2 so as to be movable back and forth in the directions of arrows A1 and A2. Then, the ink layer 10 of the ink ribbon 2 is written as a primary recording image on the intermediate transfer roller 3 by the selective heat generation of the heating element of the thermal head 1, and as the intermediate transfer roller 3 rotates, an arrow mark is formed. C
Is conveyed in the direction. On the other hand, the ink ribbon 2 is conveyed in the direction of arrow D by frictional drive with the intermediate transfer roller 3.

The ink ribbon 2 conveyed in the direction of the arrow D is taken up by driving the take-up bobbin 11, and the take-up speed at this time is the take-up bobbin 11.
Since it varies depending on the size of the winding radius of the intermediate transfer roller 3, it is necessary to make it faster than the conveying speed of the intermediate transfer roller 3. This is absorbed by providing a slip mechanism (not shown) in the winding mechanism of the winding side bobbin 11. It is supposed to do.

On the other hand, a pressure roller 5 is provided which is capable of advancing and retracting in the directions of arrows B1 and B2 with respect to the intermediate transfer roller 3 via the printing paper 6. The pressure roller 5 moves in the direction of arrow B1 to retransfer the primary recording image onto the printing paper 6 and presses the printing paper 6 against the intermediate transfer roller 3 heated to a predetermined temperature. is there. The printing paper 6 thus retransferred is conveyed in the direction of arrow E.

Next, the structure of the heater 4 built in the above-mentioned intermediate transfer roller 3 will be described.

The heater 4 heats the intermediate transfer roller 3 from the inside and raises the surface temperature of the intermediate transfer roller 3 to form a primary recording image of the ink layer 10 on the intermediate transfer roller 3 without fail. This is for keeping the primary recording image at a temperature at which it can be retransferred to the printing paper 6.

Therefore, the set temperature of the intermediate transfer roller 3 is set to the ink layer 10 when the primary recording image is formed.
The melting point should be lower than the melting temperature in consideration of the material characteristics, and the pressure contact force of the pressure roller 5 can be made as small as possible when the primary recording image is retransferred to the printing paper 6. Consideration must be given to the temperature so that the pressure contact does not adversely affect others.

However, if the temperature of the intermediate transfer roller 3 is set to be too low as the temperature at which the ink layer 10 of the ink ribbon 2 is not melted, it is suitable for forming the primary recording image, but the primary recording image is formed. Is re-transferred onto the printing paper 6, the pressure contact force must be increased by the lower temperature of the intermediate transfer roller 3, and the impact thereof adversely affects precision parts and shortens the life. However, the cost increases due to the use of parts that can withstand the strength.

On the other hand, if the temperature of the intermediate transfer roller 3 is set high in order to reduce the pressure contact force of the pressure roller 5, the ink layer 10 is melted at the time of forming the primary recording image, and this ink layer is melted. 10 cannot be formed on the intermediate transfer roller 3 as a primary recording image.

According to the experimental results in consideration of the above, the optimum temperature for forming the primary recording image on the intermediate transfer roller 3 is in the range of 50 ° C. to 60 ° C., and the primary recording image is retransferred to the printing paper 6. The optimum temperature for this is in the range of 60 ° C. to 75 ° C., and it can be seen that the optimum temperatures of the two are slightly different. Therefore, it is necessary to set and control the temperature to 60 ° C. which satisfies the optimum temperature for both the temperature for forming the primary recording image and the temperature for retransfer, but this is technically difficult.

Therefore, in this embodiment, the mounting position of the heater 4 is arranged closer to the pressure roller 5 side than the center position of the intermediate transfer roller 3 as shown in FIG. The surface temperature of the pressure roller 5 is higher on the pressure roller 5 side than on the thermal head 1 side. The extent to which the heater 4 is moved from the center of the intermediate transfer roller 3 to the pressure roller 5 side depends on the relationship between the temperature for forming the primary recording image and the temperature for retransferring the primary recording image, and the platen. It is determined by the relationship between the outer diameter and the inner diameter of the intermediate transfer roller 3 which also functions as a roller.

Specifically, when the outer diameter of the intermediate transfer roller 3 is 24 mm, the inner diameter is 18 mm, and the diameter of the heater 4 is 8 mm, the position of the heater 4 is from the center of the intermediate transfer roller 3. It may be brought to the pressure roller 5 side by about 2 to 3 mm. When the heater 4 is controlled to about 50 ° C. by the thermistor 7, the actual temperature of the intermediate transfer roller 3 is 5 on the thermal head 1 side.
0 ° C to 60 ° C, 60 ° C to 7 on the pressure roller 5 side
It becomes a temperature range of 5 ° C. and can be maintained at each appropriate temperature.

Next, the operation of this embodiment will be described.

First, the thermal head 1 is moved in the direction of arrow A1 to bring the ink ribbon 2 into pressure contact with the intermediate transfer roller 3. At this time, the surface temperature of the portion of the intermediate transfer roller 3 where the ink layer 10 is brought into pressure contact with the thermal head 1 has a surface temperature of the ink layer 10 of the ink ribbon 2 by the heater 4.
Is an appropriate temperature that does not melt, that is, 50 ℃ according to the experiment
It is kept warm by heating to ~ 60 ° C.

Then, in this state, the thermal head 1
By selectively heating a plurality of heating elements of the ink layer 10, the ink layer 10 is transferred onto the surface of the intermediate transfer roller 3,
It is held and a primary recording image is formed. When the intermediate transfer roller 3 is rotated in the direction of arrow C by a drive source (not shown), the ink ribbon 2 is conveyed in the direction of arrow D at a constant speed due to the frictional force with the intermediate transfer roller 3.

On the other hand, when the primary recording image transferred onto the intermediate transfer roller 3 is conveyed to the position where it contacts the pressure roller 5 by the rotation of the intermediate transfer roller 3, the pressure roller 5 causes the arrow B1 to move. Moving in the direction, the printing paper 6 and the primary recording image are pressed against the intermediate transfer roller 3. At this time, the surface temperature of the portion of the intermediate transfer roller 3 which is pressed against the pressure roller 5 is kept at a temperature suitable for retransfer by the heater 4, that is, 60 ° C. to 75 ° C. according to experiments. Therefore, the primary recording image can be reliably retransferred to the printing paper 6. Also, this pressure roller 5
The pressure contact force of the ink ribbon 2 depends on the material of the ink ribbon 2, the retransfer temperature,
In the experiment, a load of at least 1 kg / cm 2 or more was required, although it depends on the conditions such as the hardness of the intermediate transfer roller 3. After that, the printed printing paper 6 is conveyed in the direction of arrow E according to the rotation of the intermediate transfer roller 3, and when the pressure roller 5 retreats in the direction of arrow B2 to open the printing paper 6, the printing by the thermal transfer printer is finished. .

Next, the case of performing color printing according to the above-described first embodiment will be described. First, in order to print the first color, the ink ribbon 2 is cueed. That is, the ink ribbon 2 used for color printing is Y
(Yellow), M (magenta), C (cyan), and B (black) are sequentially coated with ink for an area corresponding to one screen.
The head portion of the Y ink layer 10 or each ink layer 10
A marker for sensing is printed on the border of the. Therefore, a sensor (not shown) detects this marker and the color printing is started. Then, similar to the monochrome printing described above, first, the thermal head 1 presses the color ink ribbon 2 against the intermediate transfer roller 3 heated to a suitable temperature of 50 ° C. to 60 ° C. by the heater 4, and the thermal head is heated. By selectively heating the first heating element, a primary recording image is formed on the intermediate transfer roller 3. Then, when this primary recording image is conveyed in the direction of arrow C and sent to the position in contact with the pressure roller 5, the pressure roller 5 moves in the direction of B1 and is heated by the heater 4 to an appropriate temperature of 60 ° C to 75 ° C. The printing paper 6 and the primary recording image are brought into pressure contact with the surface portion of the intermediate transfer roller 3 thus formed, and the primary recording image is retransferred onto the printing paper 6. In this way, color printing by the Y (yellow) ink layer 10 of the first color is completed.

Next, in the case of performing color printing with the second color M (magenta) ink layer 10, first, the thermal head 1 is retracted in the direction of arrow A2 and brought into contact with and separated from the intermediate transfer roller 3, and the color is transferred. The ink ribbon 2 is set in a free state, the color ink ribbon 2 is wound around the winding side bobbin 11, and the M (magenta) ink layer 10 is formed.
Cue out. Then, the printing paper 6 is back-fed by the amount of the printing operation carried by the driving source (not shown) and returned to the printing start position. Then, color printing is performed in the same manner as the printing of the first color. The other C (cyan) and B (black) ink layers 10 are also printed in the same manner to obtain the final printed matter.

According to the first embodiment, the temperature optimum for the formation of the primary recording image and the optimum temperature for the retransfer can be easily controlled by only one heater 4 and one thermistor 7, so that the cost is low. Moreover, since the formation and retransfer of the primary recording image are stably performed, an image having a uniform print density can be obtained.

Further, since the retransfer is surely performed under the optimum temperature, the ink layer 10 does not remain on the intermediate transfer roller 3 and the cleaning mechanism of the intermediate transfer roller 3 is not necessary, and the parts cost can be reduced. .

Next, a second embodiment of the thermal transfer printer of the present invention will be described.

In this embodiment, as the pressure roller 5, a drum 8 around which the print paper 6 is wound around by a fixing device such as a clamper 9 is arranged so as to be movable back and forth in the directions of arrows F1 and F2. The perimeter of this drum 8 is
In order to be able to wrap one page of the paper around the outer circumference, it is formed to have a length equal to or more than the length of one sheet of paper.
For example, in the case of A4 paper, the diameter of the drum 8 is 100
Need to be mm. Further, the clamper 9 which is the fixing device can be opened and closed by a driving source (not shown), and fixes or releases the printing paper 6 to the drum 8. Other than that, the basic configuration and operation are the same as those of the above-described first embodiment. That is, the heater 4 of the intermediate transfer roller 3 is set so that the surface temperature of the intermediate transfer roller 3 is maintained at the optimum temperature in the portion where the primary recording image of the ink layer 10 is formed and the portion where the retransfer is performed. It is arranged closer to the drum 8 than the center. The ink layer 10 of the ink ribbon 2 is transferred onto the intermediate transfer roller 3 by pressing the thermal head 1 against the intermediate transfer roller 3 via the ink ribbon 2 and selectively heating it. As a result, a primary recorded image is formed. When this primary recording image is conveyed to the position where it is pressed against the drum 8 as the intermediate transfer roller 3 rotates, the drum 8 moves in the direction of arrow F1 and is higher than the temperature of the primary recording image forming portion. The printing paper 6 is transferred to the intermediate transfer roller 3 which is maintained at an appropriate temperature.
And press the primary recorded image. The pressure contact force at this time varies depending on the material of the ink layer 10, the retransfer temperature, the hardness of the intermediate transfer roller 3 and the like, but in this embodiment, at least 1 kg / cm @ 2 or more is required as in the first embodiment. It was

Thereafter, as the intermediate transfer roller 3 rotates in the direction of arrow C, the printing paper 6 also rotates with the drum 8, and the primary recording image is retransferred to the printing paper 6. When the printing of one page is completed by repeatedly forming and retransferring the primary recording image as described above, the clamper 9 releases the printing paper 6 by a driving source (not shown) to obtain the final printed matter. Become. At this time, since the outer circumference of the drum 8 is formed to be slightly longer than the length of the printing paper 6, the drum 8 makes one rotation.

On the other hand, when performing color printing in the second embodiment, the ink ribbon 2 is replaced with the color ink layer 10.
Is Y (yellow), M (magenta), C (cyan), B
The color ink ribbon 2 formed in the order of (black) is used. Then, the printing with the Y (yellow) ink layer 10 of the first color may be performed in the same process as the monochrome printing described above.

Then, in the case of color printing using the second color ink layer 10, the thermal head 1 is first brought into contact with and separated from the intermediate transfer roller 3 after the printing of the first color is completed. The ribbon 2 is set in a free state, and the winding-side bobbin 11 is rotated by a drive source (not shown) to be conveyed in the winding direction, and the second color M (magenta) ink layer 10 is indexed.

On the other hand, although it is necessary to return the printing paper 6 to the printing start position, in the present embodiment, the drum 8 may be rotated by a predetermined correction value without back feeding. That is, at the end of printing the first color,
Since the drum 8 is stopped at a position where it makes almost one rotation, the next color printing can be easily started by rotating the drum 8 so as to correct the error between this position and the printing start position. Further, the printing paper 6 is conveyed while being fixed by the clamper 9 and wound around the drum 8 during the color printing, and when the color printing by the last color ink layer 10 is completed, the clamper 9 is carried out. 9
And released from the drum 8.

According to the second embodiment as described above, the optimum temperature for forming the primary recording image and the optimum temperature for retransfer can be easily controlled with only one heater 4 and one thermistor 7, so that the cost is low. An image of uniform density can be obtained.

Further, since the retransfer is stably performed at the optimum temperature, the ink layer 10 does not remain on the intermediate transfer roller 3 and the cleaning mechanism for the intermediate transfer roller 3 is not required, and the cost of parts can be reduced.

Further, since the printing paper 6 is wound around the drum 8 having a circumference of about one page of the printing paper 6 as the pressure roller 5 and the printing paper 6 is conveyed, the printing paper 6 can be easily moved to the printing start position. It can be conveyed, and color printing of the second and subsequent colors can be started quickly.

The present invention is not limited to the above embodiment, but can be modified as necessary.

For example, instead of changing the arrangement of the heater 4 for heating the intermediate transfer roller 3, the heater 4 having a high heating power is provided on the pressure roller 5 side and the heater 4 having a low heating power is provided on the thermal head 1 side. You may make it arrange | position and you may make it produce a temperature difference.

[0046]

As described above, according to the thermal transfer printer of the present invention, it is possible to easily control the optimum temperature for forming the primary recording image and the optimum temperature for retransfer, and obtain an image of uniform density. be able to.

Further, since the retransfer is performed under the optimum temperature, the ink layer does not remain on the intermediate transfer roller, the cleaning mechanism for the intermediate transfer roller is not required, and the parts cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a partial configuration of a thermal transfer printer according to a first embodiment of the present invention.

FIG. 2 is a partial configuration sectional view of a thermal transfer printer according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram regarding a position of a heater in the embodiment of the present invention.

FIG. 4 is an explanatory diagram regarding a position of a heater in a conventional thermal transfer printer.

[Explanation of symbols]

 1 Thermal Head 3 Intermediate Transfer Roller 4 Heater 5 Pressure Roller 6 Printing Paper 7 Thermistor 8 Drum 9 Clamper 10 Ink Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Goto No.7 Yukiya Otsuka-cho, Ota-ku, Tokyo Alps Electric Co., Ltd. (72) Toshiaki Amano No.7 Yukiya-Otsuka-cho, Ota-ku, Tokyo Alp Su Electric Co., Ltd.

Claims (3)

[Claims] 1. A primary recording image of an ink layer of an ink ribbon is formed on the intermediate transfer roller by selectively contacting a thermal head with an intermediate transfer roller, which is a rotating body containing a heater, and is selectively heated. In a thermal transfer printer in which the primary recording image is heated on the intermediate transfer roller and is re-transferred to a print sheet by pressing with a pressure roller, the surface temperature of the intermediate transfer roller is higher than that on the side on which the primary recording image is formed. A thermal transfer printer, characterized in that the intermediate transfer roller is heated by the heater so that the transfer side becomes higher. 2. The thermal transfer printer according to claim 1, wherein the heater is arranged at a position closer to the side of retransfer than the center of the intermediate transfer roller. 3. The thermal transfer printer according to claim 1, wherein a fixing tool for fixing the printing paper is provided on the outer circumference of the pressure roller.