JP3832097B2 - Thermal head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, an elongated heating element disposed on a substrate is pressed in the width direction of a thermal transfer ribbon, the ink on the thermal transfer ribbon is melted by the heat of the heating element, and the melted ink is applied to a recording medium on a platen. The present invention relates to a thermal head for transferring and printing.
[0002]
[Prior art]
This type of thermal head is configured by disposing a long and narrow heating element at the end of the surface of the substrate and attaching a metal support plate to the back surface of the substrate.
[0003]
In the thermal transfer printing apparatus, one end of the support plate is supported so as to be swingable, and when the support plate is swung, the heating element at the end of the substrate is pushed toward the platen via the thermal transfer ribbon. The thermal head is incorporated so that it can be applied. A recording medium is positioned on the platen.
[0004]
While the recording medium and the thermal head are moved relative to each other and the thermal transfer ribbon is run along with the relative movement, the ink on the thermal transfer ribbon is melted by the heat generated at a predetermined portion of a large number of heating elements constituting the heating element. The transferred ink is transferred onto the recording medium, whereby continuous printing on the recording medium is performed.
[0005]
In such a thermal head, since the thermal transfer ribbon is configured to travel along the heating element, the thermal transfer ribbon is required to travel stably along the heating element in order to ensure good printing. . In particular, when a wide thermal transfer ribbon is used, meandering is likely to occur. When the meandering occurs, wrinkles are generated on the thermal transfer ribbon, and the printing is distorted. Therefore, a guide for preventing the meandering by guiding the running of the thermal transfer ribbon to the thermal head is provided as necessary.
[0006]
Japanese Patent Publication No. 7-98399 proposes a thermal head provided with such a guide portion for preventing meandering. A concave groove guide having a width corresponding to the thermal transfer ribbon is provided on the downstream side in the running direction of the thermal transfer ribbon, and the both ends of the thermal transfer ribbon are applied to or aligned with both ends of the groove guide to prevent meandering. This type of thermal head.
[0007]
[Problems to be solved by the invention]
However, even if both ends of the thermal transfer ribbon are regulated by concave groove guides and a force to bring them to the center is applied to the both ends, the thermal transfer ribbon has a thin strip shape, so there is almost no execution force to prevent meandering. There was a problem. In particular, when a concave groove guide is applied to a wide thermal transfer ribbon, there is a problem that wrinkles are generated at both ends of the thermal transfer ribbon, and good printing cannot be maintained. Thus, the prevention of meandering and the prevention of wrinkles are contradictory requirements.
[0008]
The present invention has been made in view of the problems of the related art, and an object of the present invention is to provide a thermal head that can reliably prevent meandering of a thermal transfer ribbon and can prevent wrinkles as much as possible.
[0009]
[Means for Solving the Problems]
The invention according to claim 1, which solves the above problem, includes a substrate attached to a support plate,
An elongate convex heating element that extends in the width direction of the thermal transfer ribbon that can travel and is disposed on the substrate so as to be able to be pressed together with the thermal transfer ribbon toward the platen;
A protrusion formed integrally with the support plate and disposed on the downstream side in the running direction of the thermal transfer ribbon from the heating element on the substrate;
A guide portion that is provided on the protruding portion so as to protrude integrally toward the heating element, and that guides the thermal transfer ribbon after being placed along the heating element,
The guide portion is provided symmetrically on a parallel portion that is parallel to the heating element and guides a central portion of the thermal transfer ribbon, and on both side portions in the width direction of the parallel portion, with both end portions of the thermal transfer ribbon at both ends. The first and second inclined portions that are guided in a relaxed state,
Furthermore, the protruding end of the parallel part is
The heat transfer ribbon is arranged so that the heat transfer ribbon is wound around the convex heating element, and the heat transfer ribbon is moved away from a tangential plane on the recording medium including a pressing point of the heat generation element for pressing the heat transfer ribbon against the platen. There is a thermal head.
[0010]
A large number of heating elements constituting an elongated heating element disposed on the substrate so as to be able to be pressed together with the thermal transfer ribbon toward the platen are selectively heated, and the ink of the thermal transfer ribbon is transferred to a recording medium for printing. The thermal head provided with the heating element and the recording medium move relative to each other, and the thermal transfer ribbon also runs along with the relative movement.
[0011]
Since a guide portion that protrudes toward the heating element is provided at a protruding portion that is disposed downstream in the running direction of the thermal transfer ribbon, the thermal transfer ribbon that has finished printing due to the heat generated by the heating element is guided by the guide portion. The Since the parallel portion at the center of the guide portion is parallel to the heating element, the thermal transfer ribbon is pulled from the contact portion between the heating element and the recording medium according to the extent that the parallel portion protrudes toward the heating element. The peeling angle is determined. The degree to which the parallel part of the guide part protrudes toward the heating element is determined in advance so that the peeling angle is appropriate.
[0012]
Since the first and second inclined portions are symmetrically provided at both ends of the parallel portion of the guide portion, when the thermal transfer ribbon starts to meander, the end of the thermal transfer ribbon is more relaxed in one of the inclined portions, and the other The end of the thermal transfer ribbon is less relaxed at the inclined portion. As described above, when meandering occurs, the degree of relaxation at both ends of the thermal transfer ribbon becomes an ambassador, so that meandering is corrected so that the degree of relaxation at the first and second inclined portions is the same. Further, since both ends of the thermal transfer ribbon are not regulated and tensioned, but both ends are relaxed, the occurrence of wrinkles based on the relaxed portion is reduced. In addition, it is conceivable that the guide portion has only the first and second inclined portions having no parallel portion or a curved shape. However, even if it is effective in preventing meandering, the guide portion may be formed in the central portion of the thermal transfer ribbon. Wrinkles are likely to occur. Therefore, the trapezoid of the parallel part and the first and second inclined parts at both ends thereof is effective for correcting the meandering while preventing the generation of wrinkles.
[0013]
According to a second aspect of the present invention, the heating element has a print width for printing at a central portion excluding both end portions in the width direction, and the length in the width direction of the parallel portion is wider than the print width. 1 is a thermal head.
[0014]
The length in the width direction of the parallel part of the guide part is wider than the print width determined by disabling several dots at both ends of the many heat generating elements constituting the heat generating element in the control structure, so it corresponds at least to the print width Thus, the thermal transfer ribbon is not guided by the first and second inclined portions, and the flatness of the thermal transfer ribbon in contact with the print width of the heating element is ensured.
[0015]
A third aspect of the present invention is the thermal head according to the first or second aspect, wherein the substrate is provided with a second guide part that floats the thermal transfer ribbon directed toward the heating element so as not to rub against the substrate.
[0016]
Even when a driver IC or the like for driving a heating element is provided on the surface of the substrate, the thermal transfer ribbon is not rubbed against the substrate because the thermal transfer ribbon is guided and floated on the second guide portion. Therefore, the substrate provided with the heating element can be arranged in a posture as close to parallel as possible with respect to the platen. Then, the heating element can be disposed near the top of the semicircular projection on the edge of the substrate, for example, and the installation of the heating element on the substrate is performed in a well-balanced shape.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described together with illustrated examples. FIG. 1 is a perspective view of a thermal head of the present invention, and FIG. 2 is an enlarged side view of a portion where a heating element and a guide portion of the thermal head are located.
[0018]
In FIG. 1, the thermal head 1 includes a substrate 2 and a support plate 3 to which the substrate 2 is attached. The substrate 2 includes a heating element 11 and a second guide part 12. The support plate 3 is provided with a protruding portion 21 and a first guide portion 22. The first guide part 22 includes a parallel part 23 and first and second inclined parts 24 and 25 at both ends thereof. The support plate 3 has a function of radiating the heat generated from the heat generator 11 through the substrate 2 and is also called a heat radiating plate. Details of each part will be described below.
[0019]
The substrate 1 is formed by disposing a heating element 11 and a driver IC 13 for driving the heating element 11 on the surface of a rectangular plate made of ceramic or the like. The heating element 11 has a large number of heating elements arranged in a row in a length substantially matching the width W2 of the thermal transfer ribbon 4. As shown in FIG. 2, a rubbing portion 14 having a semicircular cross section made of glass or the like is attached to the end of the surface of the substrate 2 on the downstream side in the running direction of the thermal transfer ribbon 4. A heating element 11 having an arc-shaped cross section is attached to the surface of the rubbing portion 14 in an embedded state. The heating element 11 has an arc shape that has a center angle of ± α in the traveling direction with respect to the point A that presses against the recording medium 6 on the platen 5.
[0020]
Returning to FIG. 1, the wiring between the large number of heating elements constituting the heating element 11 and the driver IC 13 is formed on the substrate 2 as, for example, a printed wiring. The surface of this printed wiring is hardened with resin or the like. The driver IC 13 is attached to the end of the thermal transfer ribbon 4 on the substrate 2 on the upstream side in the running direction with the surface slightly protruding. Further, the wiring from the driver IC 13 is constituted by a flat and flexible wiring 15 and can be connected to a device (not shown).
[0021]
As shown in the drawing, the heating element 11 has a vertically long and elongated shape extending by the width of the thermal transfer ribbon 4. A large number of heating elements constituting the heating element 11 can be driven one by one by a driver IC 13 and a control unit (not shown). The actual printing width W1 is determined by the portion of the heating element 11 excluding several dots at both ends that are not driven.
[0022]
The second guide portion 12 is, for example, a stainless steel rod, and is fixed between the heating element 11 and the driver IC 13 and at a position closer to the driver IC 13 with an adhesive or the like. The second guide 12 is formed in such a thickness that the height in the fixed state is approximately equal to or higher than the height of the driver IC 13. The thermal transfer ribbon 4 traveling toward the heating element 11 is floated by the second guide 12 so that the thermal transfer ribbon 4 and the driver IC 13 do not contact each other.
[0023]
The support plate 3 is formed of a kind of metal that can perform heat dissipation satisfactorily, and includes a first portion 26 to which the back surface of the substrate 2 is attached, and a second portion 27 that is continuous with the first portion 26 and swings the whole. Become. The end of the second portion 27 located on the upstream side in the running direction of the thermal transfer ribbon 4 can be attached to the swing shaft 28. The wiring 15 extends to the vicinity of the swing shaft 28 through the second portion 27.
[0024]
The protruding portion 21 is formed integrally with the support plate 3 by projecting the first portion 26 further downstream from the end surface 2a of the substrate 2 located downstream of the thermal transfer ribbon 4 in the traveling direction. A first guide portion 22 that protrudes integrally from the protruding portion 21 toward the heating element 11 is further formed.
[0025]
The first guide part 22 is a trapezoidal mountain shape that competes toward the heating element 11, and includes a parallel part 23 in the center part, a first inclined part 24 arranged symmetrically at both ends of the parallel part 23, and a first part. 2 inclined portions 25. The parallel portion 23 is disposed so as to have an equal length in the width direction from the center position of the heating element 11. The parallel portion 23 has a top that is rounded in the running direction of the thermal transfer ribbon 4, and a ridge line that continues in the width direction of the top is parallel to the heating element 11. The width W3 of the parallel portion 23 in the width direction is slightly wider than the print width W1 of the heating element 11 and narrower than the ribbon width W2.
[0026]
The first inclined portion 24 and the second inclined portion 25 have a top that is rounded toward the running direction of the thermal transfer ribbon 4. The ridge line extending in the width direction of the top is inclined so as to be sequentially away from the heating element 11 and toward the protruding portion 21. The thermal transfer ribbon 4 is hung on the first inclined portion 24 and the second inclined portion 25 by (W2-W3) / 2, and the thermal transfer ribbon 4 in this portion is in a relaxed state. It is preferable that the thermal transfer ribbon 4 is applied to 1/3 or more of the length of the first inclined portion 24 and the second inclined portion 25. Moreover, the 1st inclination part 24 and the 2nd inclination part 25 may incline along the curved shape of convex upwards instead of a straight inclination like illustration.
[0027]
The structure of another thermal head of the present invention will be described with reference to FIG. The part different from FIG. 1 is the shape of the first guide part. The illustrated first guide portion 32 is provided on the protruding portion 21 so as to protrude from the end surface 2 a of the substrate 2 toward the tip of the protruding portion 21. The first guide portion 32 includes a parallel portion 33 having a surface parallel to the end surface 2a, and a first inclined portion 34 and a second inclined portion 35 that are provided symmetrically at both ends of the parallel portion 33 and are curved toward the end surface 2a. It has become. Of the parallel part 33, the first inclined part 34, and the second inclined part 35, the part in contact with the thermal transfer ribbon 4 is processed to be rounded.
[0028]
The central portion of the thermal transfer ribbon 4 is guided in parallel with the heating element 11 on the ridge line 33 a of the parallel portion 33. Both end portions of the thermal transfer ribbon 4 are guided by ridge lines 34a and 35a of the first inclined portion 34 and the second inclined portion 35 so as to be relaxed toward the ends.
[0029]
Next, an outline of the structure of a serial thermal transfer printing apparatus to which the thermal head described in FIGS. 1 to 3 is applied will be described with reference to FIG.
[0030]
The thermal head 1 shown in FIG. 1 is attached to the print head 7 so as to be swingable toward the platen 5 by a swing shaft 28. Further, a ribbon cartridge 8 is attached to the print head 7 so as to be fitted from above the drawing. The thermal transfer ribbon 4 passes from the supply reel 41 through the guide 42, passes through the second guide portion 12, the heating element 11, and the first guide portion 22 of the thermal head 1, and reaches the take-up reel 44 through the guide 43. In the illustrated example, the thermal head 1 is swung in the direction of the arrow a <b> 2 and the heating element 11 is pressed against the platen 5 via the thermal transfer ribbon 4. When the print head 7 travels in the direction of the arrow a1, the thermal transfer ribbon 4 travels in the direction of the arrow a3, and printing is performed on the recording medium 6.
[0031]
In addition to the serial type described above, there are also line-type thermal transfer printing apparatuses. The thermal head described with reference to FIGS. 1 to 3 can also be applied to a line-type thermal transfer printing apparatus.
[0032]
Next, the operation of the thermal head 1 having the above-described structure will be described below. In FIG. 2, a number of heating elements constituting the heating element 11 pressed together with the thermal transfer ribbon 4 toward the platen 5 are selectively heated, and the ink on the thermal transfer ribbon 4 is transferred to the recording medium 6 for printing. Regardless of the serial type or the line type, the thermal head 1 and the recording medium 4 move relatively, and the thermal transfer ribbon 4 also travels along with the relative movement, and continuous printing is performed.
[0033]
The thermal transfer ribbon 4 after the ink at a predetermined location is transferred by the heating element 11 reaches the parallel portion 23 of the first guide portion 22 and is guided in contact with the point B shown in the drawing. Since the line formed by the contact point B of the parallel portion 23 continuously in the longitudinal direction of the paper and the line formed by the pressing point A of the heating element 11 continuous in the longitudinal direction of the paper are parallel to each other, they are parallel to the heating element 11. The peeling angle θ at which the thermal transfer ribbon 4 is peeled off from the point A which is the contact portion is uniquely determined by the position of the point B determined by the extent to which the portion 23 protrudes. The degree to which the parallel part 23 protrudes toward the heating element 11 is determined in advance so that the peeling angle θ is appropriate. As a result, the ribbon 4 after thermal transfer is peeled off immediately from the contact portion A, and good ink transfer from the thermal transfer ribbon 4 to the recording medium 6 is ensured.
[0034]
In FIG. 1, if the thermal transfer ribbon 4 starts to meander on the upper side of the drawing, the width at which the thermal transfer ribbon 4 is relaxed at the first inclined portion 24 is wider than the width at which the thermal transfer ribbon 4 is relaxed at the second inclined portion 25. Become. In this way, if there is a difference in the amount of relaxation at both ends of the thermal transfer ribbon 4, the thermal transfer ribbon 4 on the side having a small amount of relaxation is pulled in on the side having a large amount of relaxation, and the amount of relaxation on both ends is equalized. A force to move the whole in the width direction acts. In this manner, the meandering of the thermal transfer ribbon 4 is constantly corrected by the first and second inclined portions 24 and 25.
[0035]
Further, the length W3 of the parallel portion 23 is longer than the printing width W1 determined by disabling several dots at both ends of the heating element 11. Therefore, even if the thermal transfer ribbon 4 moves slightly in the width direction due to the meandering correction of the first and second inclined portions 24 and 25, the portion of the thermal transfer ribbon 4 that is actually used for printing is parallel to the heating element 11. As a result, the flatness of the thermal transfer ribbon 4 in the printed portion is maintained. In addition, since the meandering correction by the first and second inclined portions 24 and 25 is performed with a force over the entire thermal transfer ribbon 4, wrinkles are hardly generated from both end portions of the thermal transfer ribbon 4. As described above, the first guide portion 22 of the present invention simultaneously achieves seemingly contradictory demands for maintaining the flatness of the printed portion of the thermal transfer ribbon 4 and preventing the meandering of the thermal transfer ribbon 4.
[0036]
Further, the operation of the second guide portion 13 will be described below. As described with reference to FIG. 2, the heating element 11 is disposed on the rubbing portion 14. In order to arrange the heating element 11 satisfactorily, it is preferable to position the heating element 11 as close to the top of the semicircular rubbing portion 14 as possible. For this purpose, it is necessary to arrange the substrate 2 and the platen 5 as close to each other as possible.
[0037]
An example of the arrangement of such a thermal head 1 is shown in FIG. As shown in the drawing, when the substrate 2 and the platen 5 are brought close to each other in parallel, the thermal transfer ribbon 4 comes into contact with the driver IC 13 provided on the surface of the substrate 2. Although the surface of the driver IC 13 is hardened with resin, there is no flatness. Therefore, when the thermal transfer ribbon 4 comes into contact with the driver IC 13, the thermal transfer ribbon 4 is caused to meander.
[0038]
Therefore, the second guide portion 12 is provided in the vicinity of the driver IC 13 on the substrate 2 so as to be almost the same height as or higher than the driver IC, and the thermal transfer ribbon 4 is guided flatly by the second guide portion 12 without contacting the driver IC 13. Then, a gap is provided at point C to such an extent that the thermal transfer ribbon 4 guided by the second guide portion 12 does not contact the recording medium 6, and the thermal transfer ribbon 4 from a ribbon cassette (not shown) does not contact the driver IC 13. A gap is provided at the point, and the substrate 2, that is, the support plate 3 can be arranged as close to the platen 5 or the recording medium 6 as possible in parallel.
[0039]
As a result, in FIG. 2, the heating element 11 can be disposed near the top of the semicircular rubbing portion 14, and the heating element 11 is placed on the substrate 2 in a well-balanced manner, so that the heating element 11 It becomes possible to arrange with high accuracy.
[0040]
【Example】
When the width W2 of the heating element 11, that is, the thermal transfer ribbon 4 is 24 mm, and the printing width W1 determined by the inoperability of several dots at both ends of the thermal transfer ribbon 4 is 20 mm, each of the parallel portions having a width of 22 mm is provided at both ends. A first guide part 22 having first and second inclined parts 24, 25 of 4 mm was used. There was no blurring of the print that could be caused by the meandering of the thermal transfer ribbon 4, and the print was good.
[0041]
【The invention's effect】
As described above, according to the first aspect of the present invention, the parallel portion of the guide portion guides while ensuring the flatness of the thermal transfer ribbon, and the inclined portion of the guide portion guides while correcting the meandering of the thermal transfer ribbon. Further, it is possible to ensure a stable running property that the thermal transfer ribbon does not meander and to perform good printing while preventing the generation of wrinkles. For example, in a wide thermal transfer ribbon having a width of 15 mm or more, since it is not effective for meandering to restrict both ends of the ribbon like a concave groove, it consists of a parallel portion and first and second inclined portions at both ends. The ribbon guide part is particularly effective.
[0042]
In addition, since the peeling angle when the thermal transfer ribbon is peeled off from the contact portion between the heating element and the recording medium is determined by the degree of protrusion of the parallel part with respect to the heating element in the guide part, the thermal transfer ribbon is stably pulled from the recording medium. The ink is peeled off, and the transfer of the ink to the recording medium is also performed reliably.
[0043]
According to the invention of claim 2, at least the thermal transfer ribbon corresponding to the print width is guided by the parallel portion without hanging on the inclined portion, and the flatness of the thermal transfer ribbon corresponding to the print width of the heating element is ensured. The influence on the printing by the thermal transfer ribbon relaxed at the inclined portion can be cut off, and good printing by the heating element can be secured.
[0044]
According to the invention of claim 3, the second guide portion allows the substrate provided with the heating element to be arranged in a posture as nearly parallel to the platen as possible, and the installation of the heating element on the substrate is balanced in shape. As a result, it is possible to accurately dispose the heating element on the thermal head, and it is possible to ensure good printing by the heating element.
[Brief description of the drawings]
FIG. 1 is a perspective view of a thermal head of the present invention.
FIG. 2 is an enlarged side view of a portion where a heating element and a guide portion of a thermal head are located.
FIG. 3 is a perspective view of another thermal head of the present invention.
FIG. 4 is a top view of a main part of a printing apparatus in which the thermal head of the present invention is incorporated.
FIG. 5 is a top view showing a preferred example of incorporation of the thermal head of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Thermal head 2 Board | substrate 3 Support plate 5 Platen 11 Heating body 12 2nd guide part 13 Driver IC
21 Protruding portions 22, 32 First guide portions 23, 33 Parallel portions 24, 34 First inclined portions 25, 35 Second inclined portions

Claims (3)

A substrate attached to a support plate;
An elongate convex heating element that extends in the width direction of the thermal transfer ribbon that can travel and is disposed on the substrate so as to be able to be pressed together with the thermal transfer ribbon toward the platen;
A protrusion formed integrally with the support plate and disposed on the downstream side in the running direction of the thermal transfer ribbon from the heating element on the substrate;
A guide portion that is provided on the protruding portion so as to protrude integrally toward the heating element, and that guides the thermal transfer ribbon after being placed along the heating element,
The guide portion is provided symmetrically on a parallel portion that is parallel to the heating element and guides a central portion of the thermal transfer ribbon, and on both side portions in the width direction of the parallel portion, with both end portions of the thermal transfer ribbon at both ends. The first and second inclined portions that are guided in a relaxed state,
Furthermore, the protruding end of the parallel part is
The heat transfer ribbon is arranged so that the heat transfer ribbon is wound around the convex heating element, and the heat transfer ribbon is moved away from a tangential plane on the recording medium including a pressing point of the heat generation element for pressing the heat transfer ribbon against the platen. thermal head are.   2. The thermal head according to claim 1, wherein the heating element has a print width for printing at a central portion excluding both end portions in the width direction, and a length in the width direction of the parallel portion is wider than the print width.   3. The thermal head according to claim 1, wherein a second guide portion is provided on the substrate to float the thermal transfer ribbon toward the heating element so as not to rub against the substrate.

Images