JPH01152085A - Thermal transfer printer - Google Patents

Abstract

PURPOSE:To prevent generation of crease due to the heat contraction of ink film by providing a tension-giving means which gives tension to ink film between an ink film supply roll and a thermal head only when the thermal head is pressed into contact with a platen roller. CONSTITUTION:When a thermal head 10 is pressed into contact with a platen roller 5 for printing, the pawl 25a of a lever 25 is engaged with one of recessed parts between the teeth, 21a of a friction plate 21. Consequently, an ink film supply roll 7 is braked by friction force between the friction plate 21 and friction members 20, 22, and tension is supplied to ink film 6 between the thermal head 10 and the ink film supply roll 7. As a result, the heat of the thermal head 10 prevents the ink film 6 from thermally contracting, and thereby the generation of crease can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal transfer printer for printing images and the like.

[Prior Art] As one type of thermal transfer printer, there is a thermal transfer color printer that performs color printing by appropriately thermally transferring a plurality of color inks coated on an ink film onto printing paper.

As such a thermal transfer type color printer, those shown in FIGS. 3 to 5 are conventionally known.

In FIG. 3, reference numeral 1 indicates the main body of the printer.

On the back side of this printer main body l, a printing paper supply roll 3 on which printing paper 2 is wound is rotatably supported by a bracket la. As shown in FIG. 4, the printing paper 2 has feed holes 2a and 2a on both sides thereof.
... is the longitudinal direction of the printing paper 2 (in the figure, the vertical direction)
- A large number of sheets are formed in a straight line, and the portion pulled out from the printing paper supply roll 3 is a guide roller 4 provided inside the printer main body l, as shown in FIG.
After being wrapped around the platen roller 5, it is pulled out from near the center of the top surface of the printer main body l. The guide roller 4 and platen roller 5 are provided to feed the printing paper 2, and feed holes 2a, 2a, . . . for the printing paper 2 are provided at both ends of the outer peripheral surface thereof.
Smaller diameter sprocket bins 4a, 4a..., 5a,
5a... are formed at equal pitches, and these sprocket pins 4a, 4a, 5a, 5a...
It is engaged with the feed holes 2a, 2a of the printing paper 2 (see FIG. 4). Then, the platen roller 5
The shaft end of is connected to a motor (not shown), so that it can rotate forward (direction of arrow Y1 in the figure) and reverse (direction of arrow Y2 in the figure) around its axis.
The information is also transmitted to the guide roller 4 by a belt (not shown). The belt is wound around the guide roller 4 and the platen roller 5 so that their circumferential speeds are the same and their rotation directions are opposite.

On the other hand, an ink film 6 is provided below the guide roller 4.
An ink film supply roll 7 on which is wound up is rotatably attached. The ink film 6 is formed by repeatedly applying yellow, magenta, and cyan color inks, which are the primary colors for color image printing, in the longitudinal direction of the film, as shown in FIG. Then, the portion pulled out from the ink film supply roll 7 is wound around the outside of the printing paper 2 wound around the platen roller 5, further wound around the guide roller 8, and then transferred to the take-up roll 9. It is wound up.

The take-up roll 9 is driven by a motor (not shown).

A thermal head 10 is provided below the platen roller 5. This thermal head 10 is provided so as to be able to press against and separate from the outer circumferential surface of the platen roller 5, and sandwich the printing paper 2 between the platen rollers 5 and 5.
When the ink film 6 wrapped around the outer periphery is pressed against the ink film 6, a heat pulse is applied to the ink film 6 to perform 1. The color ink applied to the ink film 6 is thermally transferred to the printing paper 2.

In the thermal transfer color printer having the above configuration, color printing is performed according to the following procedure.

First, rotate the platen roller 5 in the forward direction (arrow Y1 direction in the figure).
and set the printing start position of printing paper 2 to the thermal head lO.
At the same time, the take-up roll 9 is rotated so that the tip position of the yellow color ink applied to the ink film 6 coincides with the printing position of the thermal head 10. Next, the thermal head 10 is brought into pressure contact with the ink film 6 wrapped around the outer peripheral surface of the platen roller 5 with the printing paper 2 interposed therebetween. Then, the platen roller 5 is rotated in the forward direction to send the printing paper 2 with the ink film 6 superimposed thereon to the paper ejection side, and heat pulses are appropriately applied to the thermal head 1O to apply yellow color ink to the printing paper 2. heat transfer to.

As described above, when yellow printing is completed, the thermal head 1O is separated from the ink film 6, and then the platen roller 5 is rotated forward again to separate the printing paper 2 and the ink film 6. Next, the platen roller 5 is rotated in the reverse direction (in the direction of arrow Y2 in the figure) to send the printing paper 2 to the paper supply side (to the right in the figure), and the printing start position of the printing paper 2 is returned to the printing position of the thermal head IO. , by slightly rotating the take-up roll 9 in the direction of arrow Y3 in the figure,
The tip of the magenta color ink applied to the ink film 6 is aligned with the mark n+1 position of the thermal head IO. Then, as in the case of yellow, the thermal head IO is brought into pressure contact with the ink film 6, the platen roller 5 is rotated forward, and the magenta color ink is thermally transferred to the printing paper 2 to print magenta, and then the above procedure is performed. Similarly, the printing paper 2 is reversely fed and the ink film 6 is
If cyan printing is performed by transporting the paper 2, a color image will be printed on the printing paper 2.

[Problems to be solved by the invention] By the way, in conventional thermal transfer color printers,
When the ink of the ink film 6 is thermally transferred to the printing paper 2 by the thermal head 10, the ink film 6 is thermally contracted by the heat of the thermal head 10, so that wrinkles occur. Therefore, there is a portion where the ink film 6 is brought into close contact with the printing paper 2 in a folded state. If thermal transfer is performed in such a state, the ink will be difficult to transfer on the folded parts of the ink film 6, so the transferred image may have uneven color or some parts may not be transferred, resulting in an undesired image. There was an inconvenience that it was not available. In color printing in which a plurality of colors are transferred in an overlapping manner, this phenomenon becomes noticeable as color unevenness in the image, resulting in poor image quality.

This invention was made in view of the above circumstances, and its purpose is to prevent the occurrence of wrinkles due to heat shrinkage of the ink film, thereby preventing uneven density and color unevenness in the transferred image. The purpose of the present invention is to provide a thermal transfer printer that can print desired characters and colors with good image quality without any parts being left blank.

[Meanings to be Solved by the Invention 1 &] In order to achieve the above object, the present invention provides an ink film supply roll that supplies an ink film, a take-up roll that winds up the ink film, a platen roller that transports printing paper, and an ink film supply roll that supplies an ink film. The platen roller is equipped with a thermal head that can be pressed against and separated from the platen roller, and with printing paper wrapped around the outer peripheral surface of the platen roller and an ink film wrapped around the outside of the printing paper, the thermal head is attached to the platen roller. In a thermal transfer printer that prints by thermally transferring the ink from the ink film to printing paper using the heat C of the thermal head, tension is applied to the ink film between the ink film supply roll and the thermal head only when the thermal head is pressed. A tension applying means is provided.

[Function] According to the present invention, since printing is performed while the ink film is being stretched, it is possible to prevent the ink film from shrinking due to the heat of the thermal head, and therefore, it is possible to prevent wrinkles from occurring. . This eliminates density unevenness, color unevenness, and untransferred areas in the transferred image.

Also, during printing, the ink film is transported by the platen roller, so the take-up roll only has to wind up the amount of ink film sent from the platen roller, so tension is not applied to the ink film between the ink film supply roll and the thermal head. Even if the winding roll is turned on, the take-up roll motor does not receive this extra torque.

On the other hand, when printing is not performed, no tension is applied to the ink film, so a conventional displacement motor is sufficient and a large torque motor is not required.

[Embodiment] An embodiment in which the present invention is applied to a thermal transfer color printer will be described below with reference to FIGS. 1 and 2.

Note that the same components as those in the conventional example are given the same reference numerals, and the explanation thereof will be omitted.

In FIG. 2, reference numerals 11S and 12 are holding shafts that hold the ink film supply roll 7. These holding shafts 11,
12 is rotatably attached to the printer main body l with the axes aligned. At the opposite shaft ends of the holding shafts 11.12, holding members 13.14 for holding the ink film supply roll 7 are respectively attached. The ink film supply roll 7 is attached between these holding members 13, 14, and is held by the biasing force of the coil spring 15, and the holding shaft 11, 12 and the ink film supply roll 7 rotate integrally.

A friction clutch 16 is attached to the other shaft end of the holding shaft 11. The friction clutch 16 is configured as follows. That is, a friction plate 19 is attached to a clutch shaft 18 that is fixed to the holding shaft j1 with a set screw 17. This friction plate 19 slides on the clutch shaft 18 in the axial direction by forming the holding shaft 11 in a vertical cross-sectional shape rDJ-shaped, and also forming the hole shape in the clutch shaft 18 in an rDJ-shape and fitting it. possible and rotates together with the clutch shaft 18. A friction member 20, a friction plate 21, and a friction member 22 are loosely fitted into the clutch shaft 18 between the friction plate 19 and a friction plate portion 18a formed in the shape of a collar on the clutch shaft 18. The outer periphery of the friction plate 21 has saw-shaped teeth 21a, 21a.
... is formed. Friction plate portion 18a, friction member 20
, friction plate 211 friction member 22, friction plate 19, friction plate 1
Coil spring 24 interposed between 9 and adjustment nut 23
It is pressed by. The adjusting nut 23 is threaded onto the clutch shaft 18 and can adjust the biasing force of the coil spring 24.

In FIG. 1, 25 is a lever rotatably attached to a fulcrum 26 attached to the printer main body l.

An engagement protrusion 25a is formed at the upper end of the lever 25, and this engagement protrusion 25a engages the teeth 21a of the friction plate 21.
, 21a... are adapted to engage with the recesses between them.

Further, the lever 25 is connected to a rod 28 by a connecting pin 27 provided between the engagement protrusion 25a and the fulcrum 26, and this rod 28 is connected to an actuator 29 that moves the rod 28 in the direction of arrow Y4 in the figure. They are connected by pins 30. The actuator 29 is connected to a control device (not shown) and is activated only when the thermal head 10 is pressed against the platen roller 5. When the actuator 29 operates, the lever 25 rotates about the fulcrum 26 in the direction of arrow Y5 in the figure, and the locking protrusion 25a is engaged with one of the recesses between the teeth 25a of the friction plate 21. Further, the lever 25 is connected to a coil spring 32 by a locking pin 31 provided below the fulcrum 26, and the coil spring 32 is fixed to the printer main body l. When the actuator 29 stops operating, this coil spring 32
As a result, the lever 25 is rotated in the direction opposite to the arrow Y5 in the figure, and is separated from the friction plate 21.

In the thermal transfer color printer configured as described above, when the thermal head 10 presses against the platen roller 5 to perform printing, one of the recesses between the teeth 21a of the friction plate 21 engages with the engagement protrusion of the lever 25. 25a is engaged, the ink film supply roll 7 is braked by the frictional force between the friction plate 21 and the friction member 20.22, and the thermal head 1
Tension is applied to the ink film 6 between the roller 0 and the ink film supply roll 7. This allows the thermal head l
The ink film 6 can be prevented from shrinking due to the heat of O, and wrinkles can be prevented.

Therefore, the transferred image has no density unevenness, color unevenness, or untransferred portions, and desired characters and colors with good image quality can be reliably printed.

Furthermore, during printing, since the ink film 6 is conveyed by the platen roller 5 together with the printing paper 2, the take-up roll 9 only has to take up the amount of ink film 6 sent from the platen roller 5. Even if tension is applied to the ink film 6 between the heads 1O, no additional torque is applied to the motor of the take-up roll 9. On the other hand, when printing is not performed, the lever 25 is separated from the friction plate 21 and the ink film supply roll 7 is not braked, so no tension is applied to the ink film 6. Therefore, a conventional capacity motor can be used, and a large torque motor is sufficient. do not need. Therefore, there is an advantage that high-quality images can be obtained without increasing the size of the motor that drives the take-up roll 9.

[Effects of the Invention] As explained above, in this invention, a tension applying means is provided that applies tension to the ink film between the ink film supply roll and the thermal head only when the thermal head is pressed against the ink film. Since printing is performed while the ink is being heated, it is possible to prevent the ink film from shrinking due to the heat of the thermal head.
Therefore, it is possible to prevent wrinkles from forming.

Therefore, the transferred image has no density unevenness, color unevenness, or untransferred portions, and desired characters and colors with good image quality can be reliably printed.

Furthermore, during printing, the ink film is transported by the platen roller, so the take-up roll only has to take up the amount of ink film sent from the platen roller, so tension is not applied to the ink film between the ink film supply roll and the thermal head. Even if the winding roll is turned on, the take-up roll motor does not receive this extra torque.

On the other hand, when printing is not performed, no tension is applied to the ink film, so a conventional capacity motor is sufficient and a large torque motor is not required. Therefore, there is an advantage that high-quality images can be obtained without increasing the size of the motor that drives the take-up roll.

[Brief explanation of the drawing]

1 and 2 are views showing one embodiment of the present invention, in which FIG. 1 is a schematic side view showing the configuration of the printer mechanism section, and FIG. 2 is a sectional view of the ink film supply roll section. , FIGS. 3 to 5 are diagrams showing a conventional thermal transfer color printer, in which FIG. 3 is a schematic side view showing the configuration of the printer mechanism, and FIG. 4 is a diagram showing printing paper and sprocket pins of the platen roller. FIG. 5 is a plan view showing the engaged state, and FIG. 5 is a plan view of the ink film. 2... Printing paper, 5... Platen roller, 6... Ink film, 7... Ink film supply roll, 9... Winding roll , IO... Thermal head, 11...
・Holding shaft, 16...Friction clutch, 21...
...Friction plate, 21a... Teeth, 25...
・Lever, 25a...Engagement protrusion, 29...
...actuator.

Claims (2)

[Claims] (1) It is equipped with an ink film supply roll that supplies an ink film, a take-up roll that winds up the ink film, a platen roller that transports printing paper, and a thermal head that is attached to the platen roller so as to be able to press against it and separate from it. With the printing paper wrapped around the outer circumferential surface of the platen roller and the ink film wrapped around the outside thereof, the thermal head is pressed against the platen roller, and the ink film is heated by the heat of the thermal head. A thermal transfer printer that prints by thermally transferring ink to the printing paper, characterized in that a tension applying means is provided for applying tension to the ink film between the ink film supply roll and the thermal head only when the thermal head is in pressure contact with the ink film. A thermal transfer printer. (2) The tension applying means is such that a friction clutch is attached to the holding shaft of the ink film supply roll, and the friction force of the friction clutch applies tension only when the thermal head is pressed into contact with the thermal head. Thermal transfer printer according to scope 1.