JPH0717488Y2 - Thermal transfer recorder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a thermal transfer recording apparatus, and in particular, in order to prevent wrinkles of an ink sheet, the pressure contact force between a thermal head and a platen roller is closer to the center than both ends. The present invention relates to an enlarged thermal transfer recording device.

(Prior Art) A thermal transfer recording apparatus has a platen roller and a thermal head that abuts against the platen roller, and the platen roller and the thermal head are pressed against each other with a predetermined pressure by an urging means such as a spring. The thermal head has a plurality of heating elements arranged in a row in the axial direction of the platen roller, and the heating elements are selectively heated based on image data. The recording paper and the ink sheet are supplied in a state of being overlapped between the platen roller and the thermal head, and while being conveyed by the platen roller, the heat of the heating element of the thermal head transfers the ink of the ink sheet to the recording paper for recording.

However, the ink sheet is thin and easily wrinkles.

Therefore, conventionally, the coefficient of friction between the platen roller and the thermal head is made larger toward the central portion than at both end sides, and the tension at the central portion of the ink sheet is made larger than at both end sides,
Prevents the generation of wrinkles. An example of such a conventional thermal transfer recording apparatus is described in Japanese Utility Model Laid-Open No. 63-139944. In this conventional thermal transfer recording apparatus, in order to make the friction coefficient between the platen roller and the thermal head larger in the central part than in both ends, the central part of the thermal head is projected in the platen roller direction.

(Problems to be solved by the invention) However, in such a conventional thermal transfer recording apparatus, as a method of preventing wrinkles from occurring in the ink sheet, the central portion of the thermal head is projected toward the platen roller, and the central portion of the ink sheet is Since the friction coefficient of the thermal head was set to be larger than the friction coefficient of both ends, the pressure contact force between the thermal head and the platen roller, that is, the printing pressure becomes larger toward the central portion of the thermal head, and the amount of heat given to the ink sheet by the thermal head at the central portion It was more and less on both ends. As a result, the recorded image transferred onto the recording paper becomes darker in the central portion and lighter in both end portions, which causes uneven density in the recorded image and deteriorates the image quality.

(Purpose of the Invention) Therefore, the present invention is to increase the heat generation amount of the heating element of the thermal head toward both ends from the central portion so that the heat amount supplied from the thermal head to the ink sheet is uniform in the axial direction of the platen roller. As another object, it is intended to prevent the occurrence of density unevenness in the recorded image of the thermal transfer recording device and improve the image quality.

(Structure of the Invention) In order to achieve the above object, the present invention includes a platen roller, a thermal head including a plurality of heating elements arranged in a row in the axial direction of the platen roller, a platen roller and a thermal head. Urging means for press-contacting, the ink sheet and the recording paper are conveyed between the platen roller and the thermal head, and the heating element of the thermal head is selectively heated based on the image data to generate heat of the heating element. The ink of the ink sheet is transferred to the recording paper according to the amount of the recording, and the pressure contact force between the platen roller and the thermal head is made larger in the central portion than in both end portions to prevent the ink sheet from wrinkling. In the thermal transfer recording apparatus, the heat generation amount of the thermal head is set to be larger at both end portions than at the central portion.

Hereinafter, a detailed description will be given based on an embodiment of the present invention.

1 to 5 are views showing an embodiment of the present invention.

FIG. 1 is a configuration diagram of a main part of the thermal transfer recording apparatus 1. In FIG. 1, 2 is a platen roller. The platen roller 2 is rotatably supported by the thermal transfer recording apparatus 1 via its shaft (not shown), and is rotationally driven in the direction of the arrow in the figure by a drive motor (not shown). A thermal head 3 is arranged above the platen roller 2, and the thermal head 3
Is urged toward the platen roller 2 by a spring (urging means) 4. Therefore, the platen roller 2 and the thermal head 3 are pressed against each other by the spring 4. The thermal head 3 is provided with a plurality of heating elements 5 arranged in a row in the axial direction of the platen roller 2 (direction perpendicular to the paper surface in FIG. 1), and the heating elements 5 selectively generate heat based on image data. To do.

The roll-shaped recording paper 6 and the ink sheet 7 are superposed and fed between the platen roller 2 and the thermal head 3, and the ink sheet 7 is positioned on the thermal head 3 side. The ink sheet 7 is sent from the sending roller 8 to the take-up roll 9,
The roll recording paper 6 and the ink sheet 7 are guide rollers.
It is supplied between the platen roller 2 and the thermal head 3 via 10. The roll-shaped recording paper 6 recorded by the thermal head 3 is cut into a predetermined length by a cutter (not shown), and then discharged to the outside of the thermal transfer recording apparatus 1 by a discharge roller. The ink sheet 7 used for recording by the thermal head 3 is wound around the winding roll 9 via the guide roller 11.

In order to prevent wrinkles from occurring in the ink sheet 7, the thermal head 3 has its central portion projected toward the platen roller 2 side rather than both ends thereof, as shown in FIG. The coefficient of friction between the ink sheet 7 and the ink sheet 7 becomes larger toward the center of the thermal head 3. Therefore, the tension when the ink sheet 7 is wound on the take-up roll 9 is large at the central portion of the thermal head 3 as shown by arrows Ta and Tb in FIG.
The tension Tb on both sides of the thermal head 3 becomes smaller and the wrinkles on the ink sheet 7 are prevented from occurring.

As shown in FIG. 4, a plurality of heating elements 5 of the thermal head 3 are arranged in a row in the axial direction of the platen roller 2, and each heating element 5 has an individual electrode 12 and a common electrode. 13 are connected. A constant voltage V is applied between the common electrode 13 and the individual electrode 12, and when the individual electrode 12 is turned on based on image data by a switching mechanism (not shown), such as a shift register and a latch, the individual electrodes turned on. electrode
The drive current 1 is supplied to the heating element 5 connected to 12.
The individual electrodes 12 are, as shown in FIG.
It is formed so as to be thinner toward the center portion with respect to both end sides, and the resistance value R is larger for the individual electrode 12 at the center portion.

Next, the operation will be described.

The thermal transfer recording apparatus 1 conveys the roll-shaped recording paper 6 by the platen roller 2 and winds the ink sheet 7 by the take-up roll 9, while the heat of the thermal head 3 melts the ink of the ink sheet 7 and roll-shaped recording paper. Recording is performed by transferring to No. 6.

At this time, as shown in FIG. 2, the central portion of the thermal head 3 projects in the platen roller 2 direction more than both ends thereof, so that the tension T acting on the ink sheet 7 is as shown in FIG. As shown, the tension Ta at the central portion becomes larger than the tension Tb at both ends thereof (see FIG. 5A), and wrinkles are prevented from occurring on the ink sheet 7.

However, since the central portion of the thermal head 3 projects toward the platen roller 2 more than both ends thereof, the force (pressure contact force) with which the thermal head 3 is pressed against the platen roller 2 by the spring 4 becomes larger toward the central portion. The printing pressure acting on recording by the thermal head 3 also increases toward the central portion of the thermal head 3. As a result, when the heating element 5 of the thermal head 3 is made to generate the same amount of heat,
Density unevenness occurs in the width direction of the roll-shaped recording paper 6.

Therefore, in the present invention, the heat generation amount of the heat generating element 5 is increased in the both end directions than in the central portion of the thermal head 3 to prevent the occurrence of density unevenness in the width direction of the thermal head 3. That is, in the present embodiment, as shown in FIG. 4, the thickness of the individual electrode 12 connected to each heating element 5 is made thicker at both end sides than in the central part (thinner in the central part), and as shown in FIG. As shown in (b), the resistance value R of the individual electrode 12 is made smaller toward the both ends than the central part. Therefore, at the time of recording, with respect to the constant voltage V supplied between the individual electrode 12 and the common electrode 13, the drive current I flowing through the heating elements 5 has the same resistance value of each heating element 5 in each heating element 5. Therefore, the amount of heat generated by the heating element 5 is larger on both ends than on the central part, and the amount of heat generated by the heating element 5 is larger on both ends than the central part of the thermal head 3. As a result, the change in the printing pressure in the width direction of the thermal head 3 can be corrected by the change in the amount of heat generated by the heating element 5, and the density of the recorded image is as shown in FIG. It becomes uniform in the width direction. Therefore, it is possible to prevent the occurrence of density unevenness of the recorded image in the width direction of the thermal head 3, and it is possible to improve the image quality of the recorded image of the thermal transfer recording apparatus 1.

In the above embodiment, in order to change the heating value of the heating element 5 in the width direction of the thermal head 3, the individual electrode 12
The thickness of the is changed, but is not limited to this. For example, as shown in FIGS. 6A and 6B, the resistance value of the heating element 5 itself may be changed. In FIG. 6, the sixth
As shown in FIG. 6 (b), a cross section taken along the line BB of FIG. 6 (a) shows that the thickness of the heating element 5 is made thicker at both ends than in the central part, and the resistance value of the heating element 5 is set at the central part Is smaller on both ends. Therefore, with respect to the constant voltage V supplied between the individual electrode 12 and the common electrode 13, the current value of the drive current I flowing through the heating element 5 becomes larger on both end sides where the resistance value is smaller,
The amount of heat generated increases toward both ends. As a result, similarly to the above-described embodiment, it is possible to prevent the occurrence of density unevenness of the recorded image in the width direction of the thermal head 3, and it is possible to improve the image quality.

Therefore, it is only necessary that the heat generation amount of the heating element can be changed according to the change of the printing pressure, and the present invention is not limited to the above-mentioned respective embodiments.

Further, in the above embodiment, the thermal transfer recording apparatus in which the thermal head 3 is projected in the platen roller 2 direction has been described, but the thermal transfer recording device in which the platen roller 2 is projected in the thermal head 3 direction to prevent the wrinkles of the ink sheet 7 is generated. The same can be applied to the recording device.

(Effect) According to the present invention, the amount of heat supplied from the thermal head to the ink sheet can be made uniform in the axial direction of the platen roller, and uneven density of the recorded image in the thermal transfer recording device can be prevented. it can. As a result, the image quality can be improved.

[Brief description of drawings]

1 to 5 are views showing an embodiment of the thermal transfer recording apparatus of the present invention. FIG. 1 is a schematic view of the essential parts of the thermal transfer recording apparatus, and FIG. 2 shows the platen roller and the thermal head. FIG. 3 is an enlarged view showing a relationship, FIG. 3 is an explanatory view of tension acting on the ink sheet, FIG. 4 is an enlarged view of a heating element portion thereof, and FIG.
(A), (b) and (c) are explanatory views of the operation of the thermal transfer recording apparatus. 6 (a) and 6 (b) are views showing another embodiment of the thermal transfer recording apparatus of the present invention. FIG. 6 (a) is an enlarged view of the heating element portion thereof, and FIG. FIG. 6 is a sectional view taken along the line BB of FIG. 1 ... Thermal transfer recording device, 2 ... Platen roller, 3 ...
Thermal head, 4 ... Spring (biasing means), 5 ...
... Heating element, 6 ... Roll recording paper, 7 ... Ink sheet, 8 ... Delivery roller, 9 ... Winding roll, 10 ... Guide roller, 11 ... Guide roller.

Claims (1)

[Scope of utility model registration request] 1. A platen roller, a thermal head having a plurality of heating elements arranged in a row in the axial direction of the platen roller, and an urging means for press-contacting the platen roller and the thermal head. The ink sheet and the recording paper are conveyed between the platen roller and the thermal head, the heating elements of the thermal head are selectively caused to generate heat based on the image data, and the ink of the ink sheet is transferred to the recording paper according to the amount of heat generated by the heating element. In the thermal transfer recording device, which transfers and records to the platen roller and the thermal head, the pressure contact force between the platen roller and the thermal head is made larger toward the center than at both ends to prevent the occurrence of wrinkles in the ink sheet. The thermal transfer recording apparatus is characterized in that the number of ends is larger than that of the central part.