JP2868375B2 - Thermal transfer printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer printer for printing by transferring ink on an ink ribbon to paper by the heat of a thermal head, and in particular, transferring the ink on an ink ribbon to an intermediate transfer member by a thermal head. The present invention relates to an intermediate transfer type thermal transfer printer that forms a primary recording image by re-transferring the primary recording image onto paper and performs desired printing.

[0002]

2. Description of the Related Art Conventionally, a thermal transfer printer which performs printing in a state where a thermal head is pressed against a platen via a sheet and an ink ribbon is often used. When printing on paper having a rough surface, it is necessary to press the thermal head with a strong pressing force, but the pressing force of the thermal head is limited due to its precise structure. Therefore, a primary recording image is formed on the intermediate transfer body by partially melting the ink of the ink ribbon by the heat generated by the thermal head and transferring the ink to the intermediate transfer body. 2. Description of the Related Art An intermediate transfer type thermal transfer printer is used in which an intermediate transfer member is transferred to a sheet by a pressure roller that presses the intermediate transfer member against the sheet with a pressing force.

FIG. 4 schematically shows such a conventional intermediate transfer type thermal transfer printer.
A cylindrical intermediate transfer roller 1 that constitutes an intermediate transfer member that is rotationally driven by a motor M is rotatably arranged. Inside the intermediate transfer roller 1, the intermediate transfer roller 1 is heated to a predetermined temperature. A heater 2 for heating is built in. In the vicinity of the intermediate transfer roller 1, a thermal head 3 is provided. This thermal head 3
Is arranged such that a plurality of heating elements 4 arranged in a straight line face the central portion of the intermediate transfer roller 1,
On both sides of the thermal head 3, a pair of ribbon rolls 7 </ b> A around which an ink ribbon 6 is wound around a bobbin 5 to guide the ink ribbon 6 substantially linearly between the intermediate transfer roller 1 and the thermal head 3. , 7B are provided. Of these, the ribbon roll 7A is on the supply side, and the ribbon roll 7B is on the winding side. Further, a pressure roller 8 that is pressed against the intermediate transfer roller 1 with a strong pressing force is rotatably disposed at a position diametrically symmetric with respect to the thermal head 3 of the intermediate transfer roller 1. A predetermined sheet 9 such as plain paper is inserted between the intermediate transfer roller 1 and the pressure roller 8, and the intermediate transfer roller 1 is driven to rotate, thereby transferring the sheet 9 to the intermediate transfer roller 1 and the pressure roller 8. And transported in the direction opposite to the running direction of the ink ribbon 6.

According to the above-described conventional thermal transfer printer,
A sheet 9 between the intermediate transfer roller 1 and the pressure roller 8
Is inserted, the pressure roller 8 is pressed against the intermediate transfer roller 1 with a strong pressing force, and the thermal head 3 is pressed against the intermediate transfer roller 1. In this state, the intermediate transfer roller 1 is driven to rotate, and 9 and the ribbon roll 7 on the winding side.
While the ink ribbon 6 is wound at a predetermined speed by B, the thermal head 3 is driven based on desired print data. As a result, the heating element 4 of the thermal head 3 generates heat and the ink of the ink ribbon 6 is partially melted and transferred to the surface of the intermediate transfer roller 1 to form a primary recording image. At this time, the primary recording image formed on the surface of the intermediate transfer roller 1 only needs to be held on the intermediate transfer roller 1, and since the surface of the intermediate transfer roller 1 is smooth, the thermal head 3 is moved to the intermediate transfer roller 1. It is not necessary to make pressure contact with 1 with such a strong pressure.

The heater 2 of the intermediate transfer roller 1
In a state where the ink transferred to the intermediate transfer roller 1 is heated to a constant temperature to generate a certain degree of viscosity in the ink, the primary recording image of the intermediate transfer roller 1 is applied to the paper 9 by the pressing force of the pressure roller 8. The desired printing can be performed on the paper 9 by retransfer. As a result, the image is retransferred onto the paper 9 by the pressure roller 8 with a strong pressing force, so that printing can be performed even on paper 9 having a rough surface such as bond paper.

On the other hand, an intermediate transfer type thermal transfer printer using an intermediate transfer belt 10 in place of the above-described intermediate transfer roller 1 is already known.

In this type of thermal transfer printer, FIG.
A cylindrical platen roller 11 is disposed so as to face, via an ink ribbon 6, a heating element 4 of the thermal head 3 which can move forward and backward in a direction indicated by an arrow. A heater 2A for heating 11 is provided. Further, a cylindrical backup roller 12 is disposed so as to face the pressure roller 8 which can move forward and backward in the direction shown by the arrow in order to press the intermediate transfer belt 10 and the paper 9 in contact with each other via the paper 9. A heater 2B for heating the backup roller 12 is provided in the roller 12, and the surface of the backup roller 12 is heated by the heater 2B.
Optimal for retransfer and at 40 ° C to 7 which does not melt ink
It is designed to be heated to a temperature of about 0 ° C.

[0008] The intermediate transfer belt 10 is wound around the platen roller 11 and the backup roller 12 under tension. Therefore, the intermediate transfer belt 10 and the paper 9 are interposed between the pressure roller 8 and the backup roller 12. The material of the intermediate transfer belt 10 may be a rubber sheet, a plastic sheet, a metal sheet, or a combination thereof, as long as it can temporarily hold a primary recording image formed of an ink layer and has a smooth surface. can do.

The platen roller 11 is driven to rotate by a motor M (not shown), and the rotation of the platen roller 11 causes the intermediate transfer belt 10 to rotate.
5, the paper 9 sandwiched between the intermediate transfer belt 10 and the pressure roller 8 also follows the travel of the intermediate transfer belt 10. Further, the ink ribbon 6 is moved in a direction indicated by an arrow by a transporting means (not shown).

[0010] Even with such a configuration, the intermediate transfer belt 10 is run in synchronization with the ink ribbon 6 and the paper 9, so that the heating elements 4 of the thermal head 3 generate heat on the intermediate transfer belt 10. The temporary recording image is formed by partially melting the ink, and then the temporary recording image on the intermediate transfer belt 10 is re-transferred to the paper 9 so that printing can be performed on the paper 9.

[0011]

As described above, the paper 9 in the prior art shown in FIG. 4 is transported by interposing the paper 9 sandwiched between the intermediate transfer roller 1 and the pressure roller 8 as described above. 1 is transmitted to the sheet 9 by friction.

However, when the sheet 9 is conveyed by such a configuration, the sheet 9 may be bent or the intermediate transfer roller 1 may be bent.
, The amount of rotation of the surface of the intermediate transfer roller 1 and the amount of conveyance of the sheet 9 do not always match.

That is, when the sheet 9 having a thickness t is in contact with the outer peripheral surface of the intermediate transfer roller 2 having a radius r and is conveyed without slipping on the outer peripheral surface of the intermediate transfer roller 2, the conveying speed V of the sheet 9 is ₀ is represented by V ₀ = (r + t / 2) · ω, where ω is the rotational angular velocity of the intermediate transfer roller 1.

The rotation speed of the motor M for driving the intermediate transfer roller 1 is calculated and set based on the transport speed V ₀ .

However, actually, the pressure roller 8
There since have been pressed by the force of pressure P ₁ to the intermediate transfer roller 1, the actual conveying speed V ₁ was made to be represented by a function F of the pressing force P ₁ as follows. V ₁ = F (P ₁ ) Further, the theoretical transport speed V ₀ and the actual transport speed V ₁ have a relationship of V ₀ <V ₁ . Here, the larger the pressure P _1, that increases substantially linearly actual conveying speed V ₁ is also confirmed.

As described above, there is a difference between the theoretical transport speed and the actual transport speed in transporting the paper 9, and the actual transport speed is higher than the theoretical transport speed. When printing is performed by setting the rotation speed of the motor M that drives the intermediate transfer roller 1 so that the paper 9 is transported at the transport speed, even if an attempt is made to print a perfect circle on the paper 9, as shown in FIG. A long ellipse is formed in the printing direction of the paper 9 and there is a problem that the printing accuracy in the transport direction of the paper 9 deteriorates.

On the other hand, the prior application of FIG. 5 has the same problem as that of FIG.

That is, when the intermediate transfer belt 10 having a thickness h is wound around the outer circumference of a platen roller 11 having a radius r and is running without slipping on the surface of the platen roller 11, the traveling speed of the intermediate transfer belt 10 is V ₂ is represented by V ₂ = (r + h / 2) · ω, where ω is the rotation angular velocity of the platen roller 11.

[0019] However, as described above with reference to FIG. 4, similar to the pressure roller 8 is pressed by the force of pressure P ₁ to the intermediate transfer roller 1, in fact, the thermal head 3
There since have been pressed with a force of P ₂ to the intermediate transfer belt 10 as shown in FIG. 5, the actual running speed V ₃ would be represented by a function F of the pressing force P ₂ by the following equation. V ₃ = F (P ₂ ) Further, the theoretical traveling speed V ₂ and the actual traveling speed V ₃ have a relationship of V ₂ <V ₃ . Here, the larger the pressure P _2, can be large almost linearly actual traveling speed V ₃ is also confirmed.

Further, in FIG. 5 as well, since the sheet 9 is theoretically held between the pressure roller 8 and the backup roller 12 via the intermediate transfer belt 10 as described with reference to FIG. Will be conveyed at a higher speed than the conveyance speed of.

As a result, in FIG. 5, the traveling speed of the intermediate transfer belt 10 and the transport speed of the paper 9 are each higher than the theoretical speed.
Similarly, the printing accuracy is deteriorated.

An object of the present invention is to provide a thermal transfer printer which overcomes the above-mentioned problems of the prior art and improves printing accuracy in an intermediate transfer system.

[0023]

According to a first aspect of the present invention, there is provided a thermal transfer printer comprising: a thermal head for partially melting ink on an ink ribbon in accordance with print data; A thermal transfer printer in which an ink ribbon is interposed and a pressure roller that is in pressure contact with the intermediate transfer body is provided, and the thermal head and the pressure roller can be freely moved toward and away from the intermediate transfer body. A motor for driving the intermediate transfer member is provided, and control means for controlling the rotation speed of the motor at a speed lower than a theoretically calculated value is provided.

According to a second aspect of the present invention, in the thermal transfer printer, an ink ribbon is interposed between a thermal head that partially melts the ink of the ink ribbon according to print data and the intermediate transfer member, and the intermediate transfer member is provided. A thermal transfer printer in which a pressure roller is provided to be in pressure contact with the intermediate transfer member, and a motor for driving the intermediate transfer member is provided. The feature is that the outer diameter of the body is made smaller than the theoretically calculated value.

Further, according to a third aspect of the present invention, there is provided a thermal transfer printer, comprising: a platen roller which faces, via the ink ribbon, a heating element of a thermal head which partially melts the ink of the ink ribbon by heat generated by the heating element in accordance with print data; The intermediate transfer belt is wound around the backup roller disposed at a distance from the platen roller while being tensioned, and a pressure roller for pressing a sheet against the intermediate transfer belt at an outer peripheral portion of the backup roller is disposed. In the thermal transfer printer described above, a motor for driving the intermediate transfer belt and control means for controlling the number of revolutions of the motor at a speed lower than a theoretically calculated value are provided.

Further, in the thermal transfer printer according to the present invention, the platen roller opposes, via the ink ribbon, a heating element of a thermal head which partially melts the ink of the ink ribbon by the heat of the heating element in accordance with print data. And a pressure roller for winding the intermediate transfer belt around the outer periphery of a backup roller disposed at a distance from the platen roller in a tension state, and pressing the sheet against the intermediate transfer belt at an outer peripheral portion of the backup roller. In the installed thermal transfer printer, a motor for driving the platen roller is provided, and the outer diameter of the platen roller is smaller than a theoretically calculated value.

[0027]

According to the present invention, by setting the peripheral speed or running speed of the roller or belt as an intermediate transfer member or the conveying speed of the paper to be lower than the theoretically calculated value in consideration of the pressing force to be applied, The accuracy of printing formed thereon can be improved.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments shown in the drawings.

FIG. 1 shows a first embodiment of a thermal transfer printer according to the present invention. The configuration of this embodiment is almost the same as that of FIG. Therefore, only the configuration different from FIG. 4 will be described here.

In FIG. 1, an intermediate transfer roller 1 constituting an intermediate transfer member is driven to rotate by a motor M, and the motor M is driven by the control of a control means 13.

In this embodiment, the control means 13 controls the motor M so as to drive the motor M at a speed lower than the theoretically calculated value required for transporting the paper 9. The intermediate transfer roller 1 and the pressure roller 8 are formed by coating an outer periphery of a cylindrical metal base with an elastic material such as rubber as necessary. Although it depends on the materials of the intermediate transfer roller 1 and the pressure roller 8 and the pressing force of the pressure roller 8, it is preferably about 80 to 99%.

According to the above-described configuration, the actual transport speed V ₁ of the paper 9, which is increased by pressing the pressure roller 8 against the intermediate transfer roller 1 with the pressure P ₁ , is made equal to the theoretically calculated value. Can be.

Therefore, according to the present embodiment, the actual transport speed of the paper 9 can be made equal to the theoretical transport speed. As a result, as shown in FIG. It can be printed as a perfect circle on the top.

Instead of the configuration of the above-described embodiment, the motor M is driven by a theoretically calculated value necessary for transporting the sheet 9, and the diameter of the intermediate transfer roller 1 is changed from the theoretically calculated value. The paper 9 may be conveyed at a reduced speed.

FIG. 3 shows another embodiment of the present invention.

The intermediate transfer member in the thermal transfer printer of FIG. 3 is constituted by an intermediate transfer belt 10 composed of a sheet-like endless belt, similar to that of FIG. 5 described above, and the structure is substantially the same as that of FIG. . Therefore, only the configuration different from FIG. 5 will be described here.

In FIG. 3, the intermediate transfer belt 10 is run by rotating a platen roller 11 facing the heating element 4 of the thermal head 3 by rotation of a motor M. Control means 13
Is driven by the above control.

In this embodiment, the control means 13 controls the motor M so that the motor M is driven at a speed lower than the theoretically calculated value required for running the paper 9. The platen roller 11, the backup roller 12, and the pressure roller 8 are formed by coating an outer periphery of a cylindrical metal base material with an elastic material such as rubber as necessary. The slow speed depends on the material of the platen roller 11, the backup roller 12, and the pressure roller 8, and the pressing force of the pressure roller 8, but is preferably about 80 to 99%.

According to the configuration described above, the thermal head 3
The actual traveling speed V ₃ of the intermediate transfer belt 10, which is increased by being pressed by the intermediate transfer belt 10 with the pressure P ₂ , can be equal to the theoretically calculated value, and the pressure roller 8 applies the pressure P 2 to the intermediate transfer belt 10. the conveying speed V ₁ of the actual paper 9 be faster by being pressed can be made equal to the calculated value of the theoretical _one.

Therefore, according to the present embodiment, the actual traveling speed of the intermediate transfer belt 10 and the actual transport speed of the paper 9 can be made equal to the theoretical transport speed (travel speed). Similarly, as shown in FIG.
The perfect circle to be printed can be printed as it is on the paper 9 as a perfect circle.

It is to be noted that, instead of the configuration of the above-described embodiment, the motor M is driven with theoretically calculated values necessary for conveying the paper 9 and running the intermediate transfer belt 10, and
The diameter of the pressure roller 8 for driving the sheet 9 and the intermediate transfer belt 10 may be smaller than the theoretically calculated value, so that the transport speed of the sheet 9 and the traveling speed of the intermediate transfer belt 10 may be reduced.

The present invention is not limited to the above-described embodiments, and various modifications can be made as necessary. For example, in the case where an intermediate transfer roller is used as the intermediate transfer member, the rotation of the intermediate transfer roller and the conveyance of the sheet may be performed by driving a pressure roller by a motor. In the case where the intermediate transfer belt is used as the intermediate transfer member, the running of the intermediate transfer belt and the conveyance of the paper may be performed by driving a backup roller or a pressure roller by a motor.

[0043]

As described above, according to the present invention, the transport speed of the sheet and the transport speed of the intermediate transfer body when the intermediate transfer body is a belt are set to be lower than the normal calculated values, so that the actual Is made equal to the normal calculated value, so that the effect that the printing accuracy can be improved in the intermediate transfer method can be achieved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a thermal transfer printer according to the present invention.

FIG. 2 is an explanatory view showing the operation of the embodiment of FIG. 1;

FIG. 3 is a configuration diagram showing another embodiment of the thermal transfer printer according to the present invention.

FIG. 4 is a configuration diagram illustrating an example of a conventional thermal transfer printer.

FIG. 5 is a configuration diagram showing another example of a conventional thermal transfer printer.

FIG. 6 is an explanatory view showing the operation of the conventional example of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Intermediate transfer roller 3 Thermal head 6 Ink ribbon 8 Backup roller 9 Paper 10 Intermediate transfer belt 11 Platen roller 12 Backup roller 13 Control means

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-62-248669 (JP, A) JP-A-3-227254 (JP, A) JP-A-57-191075 (JP, A) JP-A 63-248 172671 (JP, A) JP-A-62-109669 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/325 B41J 29/38

Claims (4)

(57) [Claims] An ink ribbon is interposed between a thermal head that partially melts the ink of the ink ribbon in accordance with print data and an intermediate transfer member, and a pressure roller that is pressed against the intermediate transfer member is provided. A thermal transfer printer in which the thermal head and the pressure roller can be freely moved toward and away from the intermediate transfer member, respectively.
A thermal transfer printer, comprising: a motor for driving the intermediate transfer member; and control means for controlling the rotation speed of the motor to be lower than a theoretically calculated value. 2. An ink ribbon is interposed between a thermal head that partially melts the ink of the ink ribbon in accordance with print data and an intermediate transfer member, and a pressure roller that is pressed against the intermediate transfer member is provided. A thermal transfer printer in which the thermal head and the pressure roller can be freely moved toward and away from the intermediate transfer member, respectively.
A thermal transfer printer, further comprising a motor for driving the intermediate transfer member, wherein the outer diameter of the intermediate transfer member is smaller than a theoretically calculated value. 3. A platen roller facing the heating element of a thermal head that partially melts the ink of the ink ribbon by the heat of the heating element according to print data via the ink ribbon, and is disposed at a distance from the platen roller. A thermal transfer printer in which an intermediate transfer belt is wound around the outer periphery of the backup roller in a tension state and a pressure roller for pressing a sheet against the intermediate transfer belt at an outer peripheral portion of the backup roller is provided.
A thermal transfer printer, comprising: a motor for driving the intermediate transfer belt; and control means for controlling the rotation speed of the motor to be lower than a theoretically calculated value. 4. A platen roller facing the heating element of the thermal head which partially melts the ink of the ink ribbon by the heat generation of the heating element in accordance with print data via the ink ribbon, and is disposed at a distance from the platen roller. A thermal transfer printer in which an intermediate transfer belt is wound around the outer periphery of the backup roller in a tension state and a pressure roller for pressing a sheet against the intermediate transfer belt at an outer peripheral portion of the backup roller is provided.
A thermal transfer printer comprising: a motor for driving the platen roller; and an outer diameter of the platen roller is smaller than a theoretically calculated value.