JPH08156301A - Color thermal transfer recording device - Google Patents

Abstract

PURPOSE: To provide a color thermal transfer recording device in which slip phenomena of recording paper are not caused. CONSTITUTION: This color thermal transfer recording device is equipped with a conveyance roller 9 which is arranged on the downstream side of the contacting interval of a platen roller 6 and a thermal head and pressed into contact with the platen roller 6. When Z1 denotes number of teeth of the gear 15 in the platen roller 6, Z2 denotes number of teeth of the gear 16 in the conveyance roller 9, ϕB denotes roller diameter of the platen roller 6 and ϕA denotes roller diameter of the conveyance roller 9, the roller diameters of conveyance roller 9 and the platen roller 6 and the gear ratio of both gears 15, 16 are set up so as to satisfy the following inequality. (Z1 /Z2 )×(ϕA/ϕB)>1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color thermal transfer recording apparatus for transferring a recording paper while carrying it during recording.

[0002]

2. Description of the Related Art Generally, in a sublimation color thermal transfer recording apparatus, gradation recording is realized by controlling the number of dots of a plurality of colors existing within a certain range on a recording paper and the degree of dot superposition. . FIG. 3 is a schematic side view of a sublimation type color thermal transfer recording apparatus of this type. A sublimation type color thermal transfer recording apparatus will be described with reference to FIG.

The ink sheet 1 includes yellow, magenta,
Inks of a plurality of colors of cyan and black are sequentially applied in the longitudinal direction with substantially the same length as the recording area. The ink sheet 1 before recording is wound around an ink sheet roll 2.

The ink sheet 1 fed from the ink sheet roll 2 is guided by the first guide shaft 4a and the second guide shaft 4b, and wound around the ink sheet take-up roll 7.

Further, the ink sheet 1 after recording is sent between a conveying roller 10 and a pressure contact roller 11 arranged in contact therewith, and the conveying roller 10 conveys the ink sheet 1 to a take-up roll 7. . That is, the ink sheet 1 fed from the ink sheet roll 2 is
After being inserted between the thermal head 5 and the platen roller 6 through the guide shaft 4a, the conveyance roller 10
And the pressure roller 11 and the second guide shaft 4b, respectively.

The recording paper 3 is wound around a recording paper roll 8 and is fed out in sequence. The recording paper 3 fed from the recording paper roll 8 is transferred to the third guide shaft 4c and the fourth guide shaft 4c.
It is guided by the guide shaft 4d and is fed between the thermal head 5 and the platen roller 6 in a state of being superposed on the ink sheet 1. The recording paper 3 fed between the thermal head 5 and the platen roller 6 is conveyed by a conveying roller 9 provided on the downstream side of the platen roller 6.

The recording paper 3 conveyed by the conveying roller 9 is guided in the direction of the guide plate 12 by the guide plates 14a and 14b. The recording paper 3 to which the ink from the ink sheet 1 is transferred is guided by the guide plate 12 and is carried out of the recording apparatus. Further, a detection device 13 is provided at a position separated by a certain distance along the conveyance path of the recording paper 3, and the detection device 13 detects the leading end of the recording paper 3.

On the other hand, the thermal head 5 has a plurality of heating resistors arranged in a line in the direction perpendicular to the recording paper surface, and the platen roller 6 is in contact with the heating resistors in a line of the thermal head 5. Are arranged.

Next, description will be given of a case where recording is performed by using the above-mentioned sublimation type color thermal transfer recording apparatus.

From the state shown in FIG. 3, while the thermal head 5 is separated from the platen roller 6, the recording paper roll 8 is reversely driven and only the recording paper 3 is rewound, and the leading end of the recording paper 3 is detected. When detected by the device 13, the rewinding is stopped.

After the thermal head 5 is pressed against the platen roller 6, the recording paper 3 is conveyed by driving the conveying roller 9 and the platen roller 6. Further, the image signal is applied to a desired heating resistor on the thermal head 5 while the ink sheet 1 is conveyed at substantially the same speed as the recording paper 3 by driving the conveying roller 10 and the pressure contact roller 11.

As a result, the heating element generates heat, the ink dye on the ink sheet 1 sublimes, and the ink dye adheres to the recording paper 3 in a dot shape, whereby yellow recording is performed.

After the recording of yellow is completed, the thermal head 5 is separated from the platen roller 6 again, and only the recording paper 3 is rewound by the distance conveyed when the recording of yellow is performed. Rewinding is stopped at the position where the leading edge of the recording paper 3 is detected.

At this time, the magenta application area of the ink sheet 1 is conveyed to a position just upstream between the contact between the thermal head 5 and the platen roller 6, so that when the thermal head 5 is pressed again, the yellow color described above is applied. Magenta recording can be performed by superimposing it on the recording area.

Thereafter, cyan and black recording is performed in the same manner as described above, and the recording of one screen is completed by superimposing and recording dots of each color.

[0016]

By the way, in the above recording, the platen roller 6 and the conveying roller 9 convey the recording paper 3, so that the conveying roller 9 is pressed against the platen roller 6 with a predetermined pressure. Then, despite the rotation, the recording paper is not conveyed in accordance with the rotation of the conveying rollers 9 and 6, a so-called slip phenomenon occurs, and the quality of the recording image quality is deteriorated.

This is because the printing surface of the recording paper used for the sublimation type recording device is slippery, and when comparing the Beck smoothness, general PPC paper etc. has about 150 sec, whereas the recording for the sublimation type recording device is The paper is 1000 seconds or longer. Therefore, the frictional force cannot be sufficiently transmitted to the recording paper 3 on the conveying roller 9 facing the printing surface of the recording paper 3 after recording, and the recording paper 3 wound around the platen roller 6 sags. This is because.

The present invention has been made to solve the above-mentioned problems, and color thermal transfer recording in which the slip phenomenon of the recording paper 3 does not occur by regulating the peripheral speed of the conveying roller 9 with respect to the platen roller 6. The purpose is to provide a device.

[0019]

SUMMARY OF THE INVENTION The present invention relates to a color thermal transfer recording apparatus for sequentially feeding an ink sheet coated with a plurality of colors of ink and recording a multi-color image on a recording medium by a recording head. A conveying roller, which is arranged on the downstream side of the contact with the recording head and is in pressure contact with the platen roller, makes the peripheral speed of the conveying roller faster than the peripheral speed of the platen roller to convey the recording medium in the forward direction. While performing recording, the diameters of the transport roller and the platen roller, and the drive of the transport roller and the platen roller are performed so that the peripheral speeds of the platen roller and the transport roller are made uniform and the recording medium is transported in the opposite direction. It is characterized by setting the gear ratio.

According to the present invention, the number of gear teeth of the drive gear of the platen roller is Z ₁ , the number of gear teeth of the drive gear of the transport roller is Z ₂ , the roller diameter of the platen roller is φB,
When the roller diameter of the conveying roller is φA, (Z ₁ / Z
₂ ) Set the roller diameters of the transport roller and the platen roller and the drive gear ratio of the transport roller and the platen roller so that the following condition is satisfied: x (φA / φB)> 1.

[0021]

According to the present invention, at the time of recording, the peripheral speed of the conveying roller is set to be higher than the peripheral speed of the platen roller, so that the slack of the recording paper wound around the platen roller is prevented and the contact between the platen roller and the recording paper is prevented. The area is increased and the frictional force between the conveying roller and the recording paper is increased.

Further, when the recording paper is fed backward, which is the non-recording state, the roll paper is wound in the positive direction, so that the platen roller and the conveying roller are rotated at a constant speed, and this portion becomes a load which becomes a back tension. be able to.

As described above, by controlling the peripheral speeds of the transport roller and the platen roller provided downstream of the transport of the recording position, it is possible to prevent the occurrence of slips and scratches on the recording paper.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. The present invention is an improvement of the portion for conveying the recording paper of the color thermal transfer recording apparatus of FIG. 3 described above, and the improvement will be mainly described. The same parts as those in FIG. 3 are designated by the same reference numerals.

FIG. 1 shows an essential part of the present invention and is an enlarged perspective view of the vicinity of a platen roller 6 and a conveying roller 9 for conveying the recording paper 3 after recording.

As shown in FIG. 1, the width of the platen roller 6 and the conveying roller 9 in this embodiment (in the direction perpendicular to the paper surface) are both 30 cm. The transport roller 9 and the platen roller 6 are made of rubber and have diameters of φA and φB, respectively. Then, the platen gear 15 having the number of teeth Z ₁ is attached to the roller shaft 6a of the platen roller 6, and the transport roller 9
A roller gear 9 having a number of teeth Z ₂ via a one-way clutch 17 is attached to the roller shaft 9a of
16 are in mesh.

The one-way clutch 17 also functions to lock when rotating in the direction of the arrow in the figure. Further, in the recording paper 3 fed between the platen roller 6 and the transport roller 9, the arrow direction in the drawing indicates the printing direction (normal transport direction).

Now, referring to FIG. 2, the continuous recording paper 3 of A3 size (420 mm × 297 mm) fed from the recording paper roll 8 is used by using the recording apparatus having the above-mentioned structure,
In order to obtain a recording image length L of 395 mm in the longitudinal direction, the pressure contact force between the thermal head 5 and the platen roller 6 is set to 6 kgf (0.2 kgf / cm), and the conveyance roller 9 and the platen roller 6 are pressure contacted. The force f is set to 1.2 and 3 kgf, and the ratio v ₂ / v ₁ of the peripheral speed v ₂ of the transport roller 9 to the peripheral speed v ₁ of the platen roller 6 is ₁ to 1.3.
FIG. 6 is a characteristic diagram showing a change in the recorded image length L when changed within the range.

As can be seen from the characteristic diagram of FIG. 2, when the peripheral speed ratio is set to 1.1 or more, the recording paper 3 is not printed at the time of recording regardless of the strength of the pressing force f of the conveying roller 9 to the platen roller 6. No slippage occurs and a recorded image of a desired length can be obtained.

This is because when the peripheral speed ratio v ₂ / v _{1 is set} to 1.1 or more, the frictional force between the platen roller 6 and the recording paper 3 increases and the slip of the recording paper 3 in the conveying direction is released. I can guess that.

On the other hand, the pressure contact force is 3 k under the same conditions as above.
It was found that only when the gf and the peripheral speed ratio v ₂ / v ₁ were set to 1.2 or more and recording was performed, a slight scratch was generated on the recording paper 3 after the recording was completed.

Based on the above facts, the present invention controls the peripheral speeds of the platen roller 6 and the conveying roller 9 as follows. That is, as described above, the platen roller 6 has the platen gear 15 (the number of teeth Z ₁ ) and the conveying roller 9 has the conveying gear 16 (the number of teeth Z ₂ ) via the one-way clutch 17.
Are attached and mesh with each other. Further, assuming that the angular velocities of the platen roller 6 and the transport roller 9 are ω ₁ and ω ₂ , respectively, the following formula can be used to satisfy v ₂ > v ₁ at the time of recording.

[0033]

[Formula 1] v ₁ = ω ₁ · (φB / 2) (1) v ₂ = ω ₂ · (φA / 2) (2)

[0034]

[Equation 2] ω ₂ = (z ₁ / z ₂ ) · ω ₁ (3)

From equation (3), equation (2) becomes as follows.

[0036]

[Formula 3] v ₂ = (z ₁ / z ₂ ) · ω ₁ · (φA / 2) (4)

From v ₂ > v ₁ , the gear ratio and roller diameter are as follows.

[0038]

[Formula 4] (z ₁ / z ₂ ) · ω ₁ · (φA / 2)> ω ₁ · (φB / 2)… (5) ∴ (z ₁ / z ₂ ) · (φA / φB)> 1… (6)

When the conditions of the platen roller 6 and the conveying roller 9 are set to the conditions shown in the above equation (6), the one-way clutch 17 works in the locking direction and operates.

On the other hand, when the recording paper is fed backward, the one-way clutch 17 does not act and v ₂ = v ₁ , and this portion has a constant back tension, and the recording paper roll 8 of the paper setting unit has a constant tension. The recording paper 3 does not slack because it is pulled back by.

In the above embodiment, the present invention is applied to the sublimation type recording apparatus, but the present invention is not limited to this, and the present invention can be applied to the recording apparatus using the recording paper having the recording surface of high smoothness.

[0042]

As described above, according to the present invention, each condition (z ₁ / z ₂ ) · (φA / φB)> 1 of the conveying roller and the platen roller provided downstream of the recording position is satisfied. As a result, it is possible to prevent slips and scratches on the recording paper, and as a result, dot misalignment does not occur and image reproducibility is improved.

[Brief description of drawings]

FIG. 1 is an enlarged view of the vicinity of a transport roller and a platen roller of the present invention.

FIG. 2 shows changes in the recording image length L in the conveyance direction of the recording paper after recording when the roller peripheral speed ratio v ₂ / v _{1 of the} present invention and the pressure contact force of the conveyance roller to the platen roller are changed. It is a characteristic diagram.

FIG. 3 is a schematic side view of a sublimation type color thermal transfer recording apparatus.

[Explanation of symbols]

 6 Platen roller 9 Transport roller

Claims (1)

[Claims] 1. A color thermal transfer recording apparatus for sequentially feeding an ink sheet coated with a plurality of colors of ink and recording a multi-color image on a recording medium by a recording head, between a platen roller and a recording head. Recording is performed while the recording medium is conveyed in the forward direction by making the peripheral speed of the conveying roller faster than the peripheral speed of the platen roller by the conveying roller arranged on the downstream side and in pressure contact with the platen roller. The roller diameters of the transport roller and the platen roller and the drive gear ratio of the transport roller and the platen roller are set so that the peripheral speeds of the roller and the transport roller are constant and the recording medium is transported in the opposite direction. Color thermal transfer recording device.