JPH0781108A - Thermal transfer recorder and ink sheet used for the recorder - Google Patents

Abstract

PURPOSE:To provide a thermal transfer recorder capable of feeding stably smoothly an ink sheet by a method wherein a carrying means of the ink sheet can be avoided from being complicated by reducing frictional force between a thermal head and the ink sheet. CONSTITUTION:In a thermal transfer recorder which carries image receiving paper 3 and an ink sheet 4 by having a speed difference between them, a lubricative layer is provided on a surface of the ink sheet 4 on a contact side with a thermal head 1. Then, a heat roller 29 which performs a carrying guide function of the thermal head 1 or the ink sheet by being used doubly as a preheating means of the ink sheet for making the lubricative layer highly lubricative is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording apparatus which makes a difference in conveyance speed between an image receiving paper and an ink sheet, and an ink sheet used in this apparatus.

[0002]

2. Description of the Related Art In a printer, a copying machine, a facsimile or the like which employs a thermal transfer system of a melting type or a sublimation type, an image receiving paper and an ink sheet are each 1: 1 / n.
2. Description of the Related Art A thermal transfer recording apparatus is known that performs printing while conveying at a speed ratio of (n> 1). With such a recording device, it is possible to save the amount of ink sheet used,
Since it is possible to increase the number of printed sheets per roll of ink sheet, it has recently attracted attention as a low running cost type recording apparatus.

In a conventional thermal transfer recording apparatus which conveys an image receiving paper and an ink sheet at the same speed, for example, the image receiving paper is conveyed while controlling the speed by a platen roller or the like, and the ink sheet is received. It was configured to convey by friction with. Further, in such a thermal transfer recording apparatus, supply tension (braking the ink sheet) is applied to the ink sheet on the supply side (feeding side), and the take-up spool is driven via the torque limiter on the take-up side. , The ink sheet was wound up without applying appropriate tension.

Generally, in this type of conventional thermal transfer recording apparatus, the frictional force between the image receiving paper and the ink sheet is larger than the frictional force between the thermal head and the ink sheet. The ink sheet take-up side does not require so much torque, and it suffices to apply a tension to the ink sheet to the extent that wrinkles and winding slack do not occur.

However, in the above-mentioned thermal transfer recording apparatus in which a predetermined speed difference is provided between the image receiving paper and the ink sheet,
The frictional action between the image receiving paper and the ink sheet and the frictional action between the thermal head and the ink sheet must be properly adjusted. That is, it is necessary to set the friction coefficient between the image receiving paper and the ink sheet low so that sticking due to friction does not occur even when the image receiving paper and the ink sheet are conveyed with a difference in speed.

Therefore, for example, Japanese Patent Laid-Open No. 62-23793.
As disclosed in Japanese Unexamined Patent Publication (Kokai), a technique for reducing the frictional force between the image receiving paper and the ink sheet has been proposed.

However, with such a configuration, the ink sheet cannot be positively conveyed by the frictional force between the image receiving paper and the ink sheet, and the frictional force between the thermal head and the ink sheet is increased. Since the resistance of the ink sheet greatly acts on the ink sheet, the ink sheet cannot be smoothly and stably conveyed.

For this reason, in order to wind up the ink sheet, a large torque must be applied to the take-up side, which leads to complication of the ink sheet conveying means and eventually to enlargement of the apparatus. Further, if the frictional force between the thermal head and the ink sheet fluctuates, the feeding of the ink sheet becomes unstable and "streaks" and the like due to uneven feeding on the image occur, which hinders high image quality. Become.

[0009]

An object of the present invention is to reduce the frictional force between the thermal head and the ink sheet,
It is an object of the present invention to provide a thermal transfer recording apparatus capable of avoiding complication of an ink sheet conveying means and stably and smoothly feeding an ink sheet. Another object of the present invention is to provide an ink sheet that can reduce the frictional force between the thermal head and the ink sheet.

[0010]

To achieve the above object, the present invention sandwiches an image receiving paper and an ink sheet having a heat-meltable or heat-sublimable ink layer between a thermal head and a platen. In a thermal transfer recording apparatus that performs printing while transporting the image receiving paper and the ink sheet at a speed ratio of 1: 1 / n (n> 1), the side that contacts the thermal head as the ink sheet. On the surface of the ink sheet, an ink sheet having a slipping layer that exhibits high slipperiness by heating is used, and the ink sheet so that the slipping layer exhibits high slipperiness during printing operation including when there is no information to be recorded. The present invention proposes a thermal transfer recording apparatus including a means for preheating.

It is effective to use a thermal head as the preheating means.

It is effective to use, as the preheating means, a heat roller located near the thermal head, on the ink sheet supply side, and in contact with the ink sheet surface opposite to the ink layer surface. Is.

Further, the preheating means heats the ink sheet at a temperature equal to or higher than the temperature at which the slipping layer becomes highly slippery and at a temperature slightly lower than the temperature at which the ink in the ink layer begins to heat melt or sublimate. It is effective to preheat.

In order to achieve the above-mentioned object, another object of the present invention is to provide a flexible substrate having an ink layer formed on one surface, a heat-resistant layer formed on the surface of the substrate opposite to the ink layer, and the heat-resistant layer. An ink sheet for a thermal transfer recording apparatus, which comprises a slipping layer formed on the above, and which has a high slipping property at a temperature lower than a temperature at which the slipping layer starts thermal melting or sublimation of the ink layer. It is a thing.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing only a main part of a thermal transfer recording apparatus according to an embodiment of the present invention. In the figure,
Reference numeral 1 indicates a thermal head, and 2 indicates a roller-shaped platen. The image receiving paper 3 is fed toward the platen 2 from a paper feeding means (not shown), and while being wound around the platen 2,
Capstan 5 and pinch roller 6 which are image receiving paper conveying means
It is transported by. Of these, Capstan 5
It is driven via a power transmission means 8 by a motor 7 which is a drive source of the image receiving paper conveying means. The power transmission means 8 comprises a worm 9 directly connected to the motor 7, and a worm wheel 10 meshing with the worm 9 and coaxially integrated with the capstan 5.

The thermal head 1 is fixed to one end of a supporting member 12 which is swingably supported around a pivot 13. The thermal head 1 is a platen 2 during printing operation.
The pressure is applied to the platen 2, and the pressure is released during the non-printing operation so that the platen 2 is separated from the platen 2. That is, the worm 15 and the worm wheel 1 that are directly connected to the motor 14 are driven by the motor 14 that is the drive source of the head pressing / separating means rotating in the forward or reverse direction.
Worm wheel 1 via a drive transmission means consisting of 6
The rocking drive plate 17 whose base end is fixed to the shaft 16a of No. 6 rocks, and the pressure spring 1 mounted between this and the head 1
The head 1 is pressed against the platen 2 via 8,
It is separated from the platen 2.

The ink sheet 4 is wound around the supply side spool 19. The supply side spool 19 is driven at a constant speed by a driving means (not shown). The conveyance speed of the ink sheet 4 is controlled by the rotation speed of the spool 19.

On the other hand, the ink sheet 4 is the spool 2 on the take-up side.
It is also wound around 0. When the motor 22, which is a drive source for ink sheet conveyance, rotates, the take-up spool 20 passes through the motor gear 23, the idle large gear 24, the idle small gear 25, and the gear 26 coaxially provided on the take-up spool 20. Rotates, and the ink sheet 4 fed from the supply side spool 19 is wound around the take-up side spool 20.

A torque limiter 27 is incorporated in the drive transmission means, and an appropriate tension is applied to the ink sheet 4 after the printing operation, which will be described later, by the action of the torque limiter.

In FIG. 1, reference numeral 29 is a roller for guiding and conveying the ink sheet toward the platen 2.

The image receiving paper 3 and the ink sheet 4 are conveyed at a speed ratio of 1: 1 / n (where n> 1) while being sandwiched between the pressurized thermal head 1 and the platen 2. To be done. When the transport speed of the ink sheet 4 is V ₁ and the transport speed of the image receiving paper 3 is V ₂ , V ₁ = V ₂ / n (n
> 1). At this time, the printing unit 28 prints.

That is, the thermal transfer recording apparatus is a thermal line type printer which performs recording scanning linearly in the axial direction of the platen 2, and has a large number of heat generating elements (in the thermal head portion facing the platen 2). (Not shown) is selectively heated according to an image signal to melt or sublimate the ink of the ink sheet 4 and transfer it to the image receiving paper 3. By performing such an operation line by line, a predetermined image is formed on the image receiving paper 3.

The transport speed of the ink sheet 4 is determined by the rotation speed of the supply side spool 19. At this time, the transport speed of the ink sheet changes depending on the winding diameter of the supply roll unit 4A, and the image receiving The ratio n to the paper transport speed also changes, but even if the value of this n changes slightly, it does not affect the image density to the left. In this case, of course, the rotation speed of the supply-side spool 19 may be controlled according to the winding diameter of the ink sheet supply roll portion 4A, and the energy applied by the thermal head 1 may be adjusted according to the n value. You may change it.

The thermal transfer recording apparatus of this example uses an ink sheet having a structure as shown in FIG. The ink sheet 4 has a flexible substrate (for example, a film base) 32 having an ink layer 31 formed on one surface, and a heat-resistant layer 33 formed on the surface of the substrate 32 opposite to the ink layer.
And a slipping layer 34 formed thereon. Among these, the ink of the ink layer 31 is of a heat melting property or a heat sublimation property. The heat-resistant layer 33 is for protecting the flexible substrate 32 from the heat of the thermal head 1. Thus, as the ink sheet, the ink sheet 4 having the heat-meltable or heat-sublimable ink layer 31 and the slipping layer 34
Is used.

In this example, the slipping layer 34 is made of a thermoplastic resin containing a slipping agent made of highly slipping molecules such as silicone oil. The slippery layer 34 has good slipperiness at room temperature, but when heated, the resin softens and the slippery agent therein floats up on the surface of the slippery layer 34 to exhibit higher slipperiness. In this way, the surface of the slipping layer 34 holds a slipping agent such as silicone oil. Then, when the ink sheet 4 is conveyed, the slipping layer 34 holding the slipping agent moves while contacting the thermal head 1 of FIG.

As described above, the thermal head 1 and the ink sheet 4 are prepared by using the ink sheet 4 having the slippery layer 34 exhibiting high slipperiness by heating on the surface in contact with the thermal head 1 as the ink sheet. The friction coefficient between and can be reduced significantly.

FIG. 4 shows the structure shown in FIG. 2, in which an ink sheet having a heat-fusible ink layer is used, and when the temperature is changed by heating the ink sheet, the relative temperature with respect to the thermal head 1 is obtained. It is a figure which shows how a friction coefficient changes. At the same time, the correlation characteristic between the temperature and the image density is also shown in this figure.

FIG. 5 is a characteristic diagram similar to that described above when the ink sheet having the structure shown in FIG. 2 and having the thermally sublimable ink layer is used.

In the former FIG. 4, the temperature T ₀ is the temperature at which the resin of the slipping layer 34 softens and the slipping layer exhibits high slipperiness. On the other hand, the temperature T is the temperature at which the ink in the ink layer 31 (FIG. 2) begins to thermally melt when the temperature of the ink sheet is increased.

In FIG. 5, the temperature T ₀ is the same temperature as described above, and the temperature T is the temperature at which the ink in the ink layer 31 starts thermal sublimation. As shown in FIGS. 4 and 5, the temperature T ₀ at which the resin of the slipping layer 34 is softened and the slipping layer 34 exhibits high slipperiness is lower than the temperature T at which heat melting or heat sublimation starts.

The temperature-friction characteristics shown in FIG. 4 or FIG. 5 can be obtained by variously adjusting and selecting the amount of highly slipping molecules (slipping agent) of the slipping layer 34 and the material of the resin. It is possible.

In any case, if the resin of the slipping layer is softened at a temperature lower than the temperature at which the ink of the ink layer begins to melt or sublime (transfer), and the slipping layer is made highly slippery, the ink layer It is possible to reduce the relative coefficient of friction between the thermal head and the ink sheet without thermally affecting the ink.

In order to achieve such high lubricity, it is necessary to preheat the ink sheet 4 itself by some means.

As a means for preheating the ink sheet 4, for example, the thermal head 1 can be used. That is, by the preheating means including the thermal head 1,
The ink sheet is preheated at a temperature slightly higher than the temperature at which the slippery layer becomes highly slippery and at a temperature slightly lower than the temperature at which the ink in the ink layer starts to be thermally melted or sublimated. When the thermal head is used as the preheating means, it is not necessary to provide another dedicated preheating means, and the recording apparatus can be further downsized.

As described above, the thermal head 1 shown in FIG. 1 is provided with a heating element (not shown) arranged in the axial direction of the platen at a portion facing the platen 2. As shown in FIG. It shows the voltage pulse applied to. According to this figure, during the printing operation, there is no information to be recorded on the 3rd line after the writing scan on the 1st line and the 2nd line. Note that FIG. 3 is a voltage pulse diagram in the case of the sublimation type recording apparatus.

During the printing operation, a constant voltage V ₀ is applied to the previous heating element regardless of whether or not there is information to be recorded. The voltage V ₀ is lower than the temperature T at which the ink in the ink layer begins to melt or sublime, and is a voltage T _{0 at} which the slippery layer 34 becomes highly slippery. The gradation is expressed by the number of pulses applied to each line, and the voltage V ₀ is applied to the heating element as an offset value regardless of the number of pulses.

During the printing operation, the temperature of the thermal head 1 is always maintained at T ₀ (FIGS. 4 and 5) by the applied voltage V ₀ . In this case, the voltage V ₀ is controlled and the temperature T ₀ is kept substantially constant depending on the density of the print information before and after, the heat generation condition of the heat generating element in the axial direction of the platen, and the difference in the ambient temperature. It is desirable to keep it.

The thermal transfer recording apparatus of this example is provided with means for preheating the ink sheet so that the above-mentioned slippery layer exhibits high slipperiness during printing operation including when there is no information to be recorded. As such a preheating means, a thermal head to which the voltage V ₀ as described above is applied can be used as an example.

As described at the beginning, when the image receiving paper and the ink sheet are conveyed with a speed difference, it becomes difficult to positively convey the ink sheet by utilizing the frictional force with the image receiving paper. There is. In such a situation, the ink sheet cannot be stably and smoothly conveyed unless the frictional force between the ink sheet and the thermal head is greatly reduced.

In the thermal transfer recording apparatus of this example, the ink sheet 4 is preheated regardless of the presence / absence of printing information.
Since the slippery layer 34 becomes highly slippery and the ink sheet 4 becomes very slippery with respect to the thermal head 1, the ink sheet can be stably and smoothly conveyed, and further image quality is further improved. be able to. Further, since the torque of the ink sheet winding means can be small, it is not necessary to make the means large-scaled, and the recording apparatus itself can be downsized.

Although the reference numeral 29 in FIG. 1 is an ink sheet conveyance guide roller, it may be used as a heat roller as a preheating means. That is, the ink sheet conveyance guide function and the preheating function are combined. Hereinafter, the ink sheet conveyance guide roller 20 will be referred to as a “heat roller”.

The heat roller 29, as shown in FIG.
The heat roller 2 includes a hollow roller main body 29A and a heat pipe 29B integrally inserted therein.
9, both ends (only one end is shown) of the side plate 35, the bearing 36
It is rotatably supported via. Heat pipe 29
A heater 38 is provided at one end of B so as to cover this portion, and the heater 3 is operated by the switching element 37.
8 is energized only during the printing operation.

When the heater 38 is energized, it generates heat and is transferred to the heat pipe 29B. Roller body 29
A is made of a material with good thermal conductivity, and the heat pipe 29
The heat transferred to B is further transferred to the roller main body 29A, and the ink sheet in contact therewith is preheated. by this,
Due to the action of the above-mentioned lubricant, the relative friction coefficient between the thermal head and the ink sheet is reduced.

It is also possible to directly embed the heater in the solid roller body 29A without using the heat pipe 29B.
By using, it is possible to achieve uniform heating of the entire roller.

The heat roller 2 which performs such a function
As shown in FIG. 1, reference numeral 9 is a position near the thermal head 1, is located on the supply side of the ink sheet 4, and is provided so as to contact the ink sheet surface (sliding layer surface) opposite to the ink layer surface. It will be. When such a heat roller is used as the preheating means, the ink sheet can be preheated independently without depending on the temperature control during the printing operation of the thermal head 1.

When the thermal head 1 shown in FIG. 1 or the heat roller 29 also serving as the ink sheet guide shown in FIG. 6 is used as the preheating means, the preheating temperature of the ink sheet is controlled by the slippery layer having a high smoothness. Even if there is information to be actually printed, if the eye temperature is slightly lower than the temperature at which the ink in the ink layer starts to be thermally melted or sublimated, even if there is information to be actually printed, a small amount of heat is applied to the ink. By adding it to the sheet, desired printing can be performed, and the printing speed can be further increased. As the ink sheet, a sheet whose slippery layer becomes highly slippery at a temperature lower than the temperature at which thermal melting or thermal sublimation of the ink layer is started is used.

The ink sheet 4 may be coated with a lubricant such as silicone oil on the side in contact with the thermal head 1 and held evenly on that side. In this case, this lubricant constitutes the lubricant layer. Even in the case of such an ink sheet, the relative coefficient of friction between the thermal head and the ink sheet can be reduced.

[0049]

According to the thermal transfer recording apparatus of the first aspect of the present invention, the ink sheet is preheated and the slippery layer is made highly slippery regardless of the presence or absence of printing information, and the ink sheet is a thermal head. On the other hand, since it becomes very slippery, the ink sheet can be stably and smoothly conveyed regardless of the presence or absence of the printing information, and further higher image quality can be achieved. Further, since the torque of the ink sheet winding means can be small, it is not necessary to make the means large-scaled, and the recording apparatus itself can be downsized.

According to the thermal transfer recording apparatus of the second aspect, it is not necessary to provide a dedicated preheating means, and the recording apparatus can be further downsized.

According to the thermal transfer recording apparatus of the third aspect, the ink sheet can be preheated independently without depending on the temperature control during the printing operation of the thermal head.

According to the thermal transfer recording apparatus of the fourth aspect, even when there is information to be printed, predetermined printing can be performed by applying a slight amount of heat to the ink sheet. It is possible to further speed up copying.

According to the ink sheet of claim 5,
When such an ink sheet is used in a thermal transfer recording apparatus, the coefficient of relative friction between the thermal head and the ink sheet can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing only a main part of a thermal transfer recording apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of an ink sheet used in the thermal transfer recording apparatus.

FIG. 3 is a diagram showing recording voltage pulses applied to a thermal head.

FIG. 4 is a diagram showing how a relative friction coefficient between an ink sheet and a thermal head changes when a heat-meltable ink sheet is used and the temperature is changed by heating the ink sheet.

FIG. 5 is a diagram showing how a relative friction coefficient between an ink sheet and a thermal head changes when a thermally sublimable ink sheet is used and the temperature is changed by heating the ink sheet.

FIG. 6 is a cross-sectional view showing another example of preheating means.

[Explanation of symbols]

 1 Thermal Head 2 Platen 3 Image Receiving Paper 4 Ink Sheet 29 Heat Roller 31 Ink Layer 32 Flexible Base 33 Heat Resistant Layer 34 Sliding Layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B41M 5/38 9121-2H B41M 5/26 101 J

Claims (5)

[Claims] 1. An image receiving paper and an ink sheet having a heat-melting or thermally sublimable ink layer are sandwiched between a thermal head and a platen, and the image receiving paper and the ink sheet are
In a thermal transfer recording apparatus that performs printing while conveying each at a speed ratio of 1: 1 / n (n> 1), the surface of the ink sheet that is in contact with the thermal head has a smooth surface that exhibits high lubricity by heating. Transfer type recording apparatus comprising an ink sheet having a flexible layer, and means for preheating the ink sheet so that the slipping layer exhibits high slipperiness during printing operation including the time when there is no information to be recorded. . 2. The thermal transfer recording apparatus according to claim 1, wherein a thermal head is used as the preheating means. 3. A heat roller used as a preheating means, which is located in the vicinity of the thermal head, on the ink sheet supply side, and in contact with the ink sheet surface opposite to the ink layer surface. The thermal transfer recording apparatus according to. 4. The preheating means heats the ink sheet at a temperature equal to or higher than a temperature at which the slipping layer becomes highly slippery, and at a temperature slightly lower than a temperature at which the ink in the ink layer starts to be thermally melted or sublimated. The thermal transfer recording apparatus according to claim 1, which is preheated. 5. A flexible substrate having an ink layer formed on one surface, a heat-resistant layer formed on the surface of the substrate opposite to the ink layer, and a slipping layer formed on the heat-resistant layer. Consists of
An ink sheet for a thermal transfer recording apparatus, wherein the slippery layer becomes highly slippery at a temperature lower than the temperature at which thermal melting or sublimation of the ink layer starts.