JPH0747704A - Thermal transfer printer - Google Patents

Abstract

PURPOSE:To prevent the forced rising and falling of the head part of a thermal transfer printer by setting the contact angle of a thermal head with a platen corresponding to the displacement between the center the width of an ink ribbon and printing center. CONSTITUTION:Since an ink ribbon 3 is forcedly allowed to fall when printing is applied only to the upper stage of an ink ribbon, the contact angle of a thermal head 3 and a platen 1 is set so as to be inclined by theta deg. in the forcedly rising direction of the ribbon 3. Since the ribbon 3 is forcedly allowed to rise when printing is applied only to the lower stage of the ink ribbon 3, the contact angle of the thermal head 3 and the platen 1 is set so as to be inclined by theta deg.in the forcedly falling direction of an ink ribbon 4. Concretely, the angle & of inclination is pref. set to theta-(1/4-10/4)DELTA1 when the displacement between the center of the width of the ink ribbon 4 and printing center is set to DELTA1mm. By this constitution, the forced rising and falling of the ink ribbon 4 at the part of the thermal head can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer printer, and more particularly, to a thermal transfer printer in which an ink ribbon can be wound well.

[0002]

2. Description of the Related Art Since an ink ribbon used in a thermal transfer printer is generally composed of an extremely thin base film having a thickness of about 4 to 8 μm, the ink ribbon itself has no rigidity. When handling such an ink ribbon, an aligned winding technique for preventing the ribbon rising and falling phenomenon that occurs in the thermal head portion is extremely important as will be described later, but there are almost no documents that have touched this technique. Absent.

[0003]

Next, the rising and falling phenomenon of the ribbon which occurs in the thermal head and the mechanism of its occurrence will be described with reference to FIGS. 8 to 10. As an example in which the phenomenon of rising and falling occurs remarkably, the case where the ribbon is pressed to the platen by the thermal head is biased to the upper side or the lower side instead of the central portion of the ribbon.

First, the phenomenon of rising and falling and the mechanism of occurrence thereof are considered as follows.

First, the rising and falling phenomenon of the ribbon requires that appropriate tension be applied to the right and left sides of the thermal head, that is, both the winding side and the discharging side. The reason is that the ribbon has no rigidity at all.

Here, the tension on the side of the precious wheel is applied by the braking force with respect to the winding tension, that is, the back tension.

Therefore, the means for adding back tension is important.

Next, even when appropriate tension is applied to the winding side and the discharging side, the phenomenon of rising and falling may occur. This phenomenon remarkably occurs particularly when a wide ribbon is used for printing in a plurality of stages.

A case where this phenomenon is lowered will be described as an example with reference to FIGS. 8 to 10. In FIGS. 8 to 10, the head 3 presses only the upper portion of the ribbon (hatched portion in the drawing) against the platen. In this state,
The winding tension To acts on the ribbon in the direction of the arrow due to the winding of the ribbon winding core 6 in the ribbon cassette. At the same time, tension Ti acts from the back tension applying portion 9 for stably running the ribbon in the opposite direction via the head.

Here, the back tension Ti is a braking force, and the adding means thereof may be other means such as a shaft brake.

The tensions To and Ti try to act uniformly and evenly over the entire width of the ribbon width R, whereas the ribbon pressing position of the head is offset to the upper side. As shown, the tension is non-uniform and the tension acting on the lower side of the ribbon is greater than the tension acting on the upper side.

That is, in the head portion, a force W for lowering the ribbon downward is generated.

Therefore, as shown in FIG. 9, the ribbon is lowered at the thermal head portion.

Here, the ink ribbon is generally about 4-8.
The ink ribbon itself has no rigidity because it is composed of an ultra-thin base film of about μm.

For this reason, the ink ribbon, which has been lowered by the thermal head and has its position deviated, does not have the ability to correct the position by itself, and the ribbon take-up core is lowered while being lowered. It will be rolled up to 6.

As described above, when the ribbon is wound while being lowered, as shown in FIG. 10, the ribbon 4 wound around the winding core 6 becomes misaligned and the cassette case for storing the ribbon is formed. The inner wall of the ribbon will come into contact with the ribbon and it will not be possible to wind the ribbon.

Further, the rise and fall cause damage such as deformation and bending of the ribbon.

The above-mentioned explanation is about the sag phenomenon that occurs in the head portion when the upper side of the ribbon is biased and pressed against the platen by the thermal head. On the contrary, the lower side of the ribbon is biased and pressed. In this case, of course, a ribbon rising phenomenon may occur and a similar problem may occur.

Further, the phenomenon that the ribbon rises and falls causes a trouble different from the fact that the ribbon cannot be wound, as will be described below.

In other words, when the head portion rises and falls, a fatal defect that the ribbon comes off from the heating resistor on the thermal head is caused.

An object of the present invention is to prevent a fatal defect such as a ribbon rising and falling phenomenon of a head portion which occurs in a thermal transfer printer.

[0022]

The features of the present invention include a thermal head, a platen against which the thermal head is pressed, an ink ribbon having a surface coated with solid ink, a ribbon cassette for accommodating the ink ribbon, and the thermal head. In a thermal transfer printer composed of a carriage or the like that moves transversely, a contact angle of a thermal head with respect to a platen is set with respect to a deviation amount of the printing center of the ink ribbon width, and a back tension is applied to the entire width of the ink ribbon. There is a point.

[0023]

With this structure, it is possible to equalize the ribbon in-plane tension generated by the ribbon winding tension To and the back tension Ti.

[0024]

EXAMPLE An example of the present invention will be described below.

FIG. 4 shows an external view of the thermal transfer printer.

A shaft 12 is fixed between the side plates 10 and 11. A carriage 13 is slidable on the shaft 12.
And the ribbon cassette 5 and the thermal head 3 are mounted on the carriage 13.
The ink ribbon 4 is housed inside.

The carriage 13 is a carriage motor 1.
4 is configured to be movable in the left-right direction in the figure via the timing belt 15. A line feed motor 16 transmits a driving force to a gear 17 fastened to the shaft of the platen 1 to feed the transfer paper 2. Further, even if the platen knob 18 is manually turned, the paper can be fed in the same manner. Reference numeral 19 is a paper guide. By moving the release lever 20 in the front-rear direction, the paper pressing roller 22 slidably arranged on the shaft 21 is pressed against the paper surface or separated from the paper surface. Reference numeral 23 is a home position sensor, and 24 is a flat cable for energizing the thermal head 3 and the like.

This printer is a one-way printing system that prints only when the carriage 13 moves to the left and right, and does not take up the ink ribbon 4 when it moves to the right. Further, the carriage motor 14, the line feed motor 16, the home position sensor 2
3. It is assumed that the thermal head 3, the ribbon sensor (not shown) that detects the end of the ribbon, and the like are controlled by the CPU 25 related to the controller.

FIG. 4 is a plan view showing a plan view showing the internal structure of the ribbon cassette embodying the present invention, which is a plan view of the cassette from which the case is removed and which is seen from above. FIG. 5 shows an AA cross section of FIG.

The ribbon cassette 5 is a cassette upper case 7
The cassette lower case 8 and the cassette lower case 8 are configured to be a hollow case by a fixing screw (not shown) or the like, and inside thereof, the ink ribbon 4 and a back tension applying portion for applying a constant back tension to the ink ribbon 4 are provided. 9 and 36 are incorporated. Also, cassette case 7
The cassette case 8 is provided with insertion notches X and Y of the heat-sensitive bed 3 mounted on the carriage 13. Reference numeral 6 denotes a ribbon winding core, and a plurality of protrusions 6a provided on the inner periphery of the ribbon winding core 6 are engaged with a ribbon winding shaft provided on a carriage, which will be described later, when the entire cassette 5 is mounted on the carriage. It has become. This cassette 5 is constructed so as to support upper and lower printing of the ribbon 4, and when the cassette 5 is mounted on the carriage, printing is performed using only the upper half of the ribbon 4. . That is, when only the upper half of the unused transfer film wound on the ribbon delivery core 26 is transferred and all the one winding is wound on the winding core 6, the ribbon cassette 5 is turned upside down. , To be reattached to the carriage. Therefore, before the ribbon cassette 5 is inverted, the untransferred portion located in the lower half of the ribbon 4 is located on the upper side by the inversion, so that the transfer can be performed to this portion. At the same time, the winding core 6 used to wind the ribbon 4 before the reversal is used as the ribbon delivery core 26 by reversing. On the contrary, by reversing the ribbon delivery core 26 that was used for delivering the ribbon before reversing, it is used as the winding core 6 and engages with the winding shaft of the carriage. Therefore, the ribbon winding core 6 and the ribbon delivery core 26 are set to have the same shape. As shown in FIG. 6, the ribbon take-up core 6 and the ribbon delivery core 26 have a slight gap between the boss portion 8a provided on the cassette case 8 and the boss portion 7a provided on the cassette case 7. Open,
The structure is such that the cassettes 5 are supported by being sandwiched so that the vertical movement of the cores 6 and 26 does not occur when the cassette 5 is inverted. 27 is a screw hole for fastening the cassette case 7 to the cassette case 8. 28 is
This is a viewing window for checking the remaining amount of the transfer film wound around the ribbon delivery core 26. Reference numerals 29 and 30 denote guide rollers arranged on the traveling path of the ribbon 4, for positioning the ribbon traveling path and reducing traveling resistance during ribbon traveling. Since the cassette 5 is used upside down, the guide rollers 29 and 30 are provided at substantially symmetrical positions. Numeral 31 is mounted on a carriage and detects that the ribbon on the delivery side is gone, or the ribbon is detached from the head at the thermal head for some reason,
Alternatively, the ribbon sensor 32 for detecting a defect that the cassette is not installed when the printer is started is a sensor insertion hole for being inserted into the cassette 5. Since the cassette 5 is used upside down, it is also inserted in the cassette case 7.
(Not shown). Reference numeral 33 is a ribbon traveling guide portion, and in order to reduce the ribbon traveling resistance, only two protrusions 33a and 33b are in contact with the ribbon. When the cassette is inverted, the protrusions 33a and 33b are substantially symmetrical. It is configured so that it becomes the position of.

Ribbon position guides 34 and 35 are provided to prevent malfunction of the ribbon sensor 32 when the ribbon is slackened when the ribbon is started or stopped, or when the head is pressed against the platen or pulled apart. is there.

Further, when the thermal head 3 moves to contact the platen after the ribbon starts traveling, the thermal head 3 pulls out the ink ribbon 4 at a large speed, so that the delivery core 26 excessively rotates due to its inertia, and becomes steady. A ribbon amount longer than that during traveling is discharged from the ribbon delivery core 26. Therefore, the winding amount of the winding core 6 cannot correspond to the feeding amount, and the ribbon sags. This slack occurs between the delivery core 26 and the back tension applying section 9. Therefore, the ribbon sensor 32 is provided at a portion where the slack of the ribbon does not occur, that is, between the back tension applying portion 9 and the thermal head 3 in the ribbon traveling path.

Next, the back tension applying portions 9 and 3
The structure of 6 will be described with reference to FIG. 7.

Friction materials (1), 3 such as felt are provided on the outer peripheral wall surface of the post 37 formed integrally with the cassette case 8.
Paste 8. On the other hand, the leaf spring 40 is attached using the post 39 as a support shaft. Then, another friction material (2) 41 such as felt is attached to the flat surface portion of the leaf spring 40.
The ink ribbon 4 is mounted between the friction materials (1) and 38 and the friction materials (2) and 41 so as to be sandwiched in a side-itch shape.
Here, the friction material (1) 38,
(2) The width T of 41 is set to be larger.
With the above-mentioned structure, even if the ribbon is displaced in the vertical direction, the friction members contact with each other at both ends.
This serves as a resistance against the displacement of the ribbon, and the displacement of the ribbon 4 at the back tension applying portion 9 or 36 can be prevented. Reference numeral 40a denotes a protruding pin contact portion that is provided integrally with the leaf spring 40. When this portion is pushed in the direction of arrow w in the figure, the friction material pushing force of the leaf spring 40 is released and the back tension is reduced. It is for canceling. When the cassette is mounted on the carriage, the protrusion pin contact portion 40a comes into contact with the outer periphery of the protrusion pin provided on the carriage to release the back tension. However, the protrusion pin (not shown) of the carriage ) Is provided at a position where the back tension of the back tension applying portion 36 on the winding side is released. Therefore, as will be described with reference to FIG. 8, the back tension of the feeding back side tension applying portion 9 acts on the ribbon, but the back tension of the winding side back tension applying portion 36 is released. Therefore, if the same back tension is applied to both the back tension applying portions 9 and 36, both in the forward traveling of the ribbon and in the backward traveling of the ribbon due to the inversion of the cassette,
Only the back tension on the sending side acts, and the size is the same, and stable ribbon running performance can be obtained.

In the cassette construction as described above, the ribbon traveling path will be described. The ink ribbon 4 unwound from the ribbon delivery core 26 has a back tension applying portion 9, a guide roller 29, a ribbon traveling guide portion 33, and a thermal head. 3, the guide roller 30, and the back tension applying portion 36 in this order, and the ribbon is wound around the ribbon winding core 6.

Next, the thermal head 3 which is the subject of the present invention
The contact angle θ ° between the platen 1 and the platen 1 will be described with reference to FIG. A ribbon cassette 5 that can be used in reverse is mounted on the carriage 13, a ribbon winding core 6 housed in the cassette 5, and a ribbon winding shaft 42 provided on the carriage 13.
Engage. The rotational force is transmitted to the ribbon winding shaft 42 through the timing belt 15, the pulley gear 43 engaged with the timing belt 15, and the winding power connection / disconnection mechanism 44 engaged with the pulley gear 43 when the carriage 13 traverses. Done. Reference numeral 45 is a ribbon winding solenoid for arbitrarily driving the ribbon winding power connecting / disconnecting mechanism 44 when the ribbon winding operation is necessary and not required.

On the other hand, the pressing operation of the thermal head 3 against the platen 1 is given by the head pressing solenoid 46. That is, a shaft 3 for supporting the entire carriage 13 and for moving the carriage 13 in a transverse direction in parallel with the platen shaft.
A head support plate 48 is arranged so as to be able to rotate by using the outer circumference of a bearing 47 provided integrally with the carriage as a guide on the outer circumference.
The thermal head 3 is mounted on the head support plate 48. The pressing operation of the thermal head 3 against the platen 1 is
The head pressing solenoid 46 attracts the plunger 49 to rotate the solenoid lever 50 engaged with the plunger 49 so that the head pressing pin 51 causes the head pressing plate 51 to move.
It is given by pressing the thermal head 3 through 8.

Here, when the thermal head 3 is pressed against the platen 1, the width dimension P of the flat portion formed on the platen surface is slightly larger than the width dimension H of the heating resistor 3a provided on the thermal head 3. Set the head pressing force, platen diameter, platen rubber hardness, etc. so that And the flat portion P
The mounting position of the heat-sensitive head 3 is set so that the center of the heat generating head 3 and the center of the width H of the antibody 3a, that is, the center of printing, substantially coincide with each other. The width R of the ink ribbon 4 is set to be at least twice the width P of the flat portion so that the upper and lower stages of the ribbon 4 can be printed.
Also, the center of the ribbon 4 width R and the print center are Δ1 as shown in the figure.
Only the upper part of the ribbon 4 is printed by shifting the position. With such a configuration, as described in detail in the section of the outline of the invention, the tension distribution acting on the ribbon surface becomes non-uniform in the upper and lower stages of the ink ribbon 3, and the lower tension is larger than the upper tension. Then, the ink ribbon 3 is slid down at the contact portion of the head 3. Therefore, as in the case of the conventional method of printing the contact angle θ ° when the thermal head 3 is pressed against the platen 1 in the center of the ribbon,
Instead of pressing it at a right angle to the platen 1, as shown in the figure, the platen 1 is tilted by θ ° and pressed.

FIGS. 2 and 3 schematically show the main points of the present invention. FIG. 2 shows a case in which only the upper stage of the ink ribbon 3 is printed. In this case, since the ribbon 3 descends, the contact angle between the thermal head 3 and the platen 1 is inclined by θ ° in the direction in which the ribbon rises as shown in the figure. To set. FIG. 3 shows a case where only the lower part of the ink ribbon is printed. In this case, since the ribbon rises, the contact angle between the thermal head 3 and the platen 1 is set by inclining the ribbon by θ ° in the direction in which it descends as shown in the figure. To do. According to the experiment, the tilt angle θ
It is preferable that the angle θ is set to approximately θ ° = (1/4 to 10/4) Δ1 (the numerical values themselves match) when the deviation amount between the ribbon width center and the printing center is Δ1 mm.

[0040]

According to the present invention, it is possible to prevent the phenomenon of the ribbon rising and falling at the head portion.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a head portion showing an embodiment of the present invention.

FIG. 2 is a sectional view of a head portion showing an embodiment of the present invention.

FIG. 3 is a sectional view of a head portion showing an embodiment of the present invention.

FIG. 4 is an external view of a printer.

FIG. 5 is a diagram illustrating an internal structure of a cassette.

6 is a cross-sectional view taken along the line AA of FIG.

FIG. 7 is a perspective view of the back tension applying portion of FIG.

FIG. 8 is a diagram illustrating tension of an ink ribbon.

FIG. 9 is a diagram for explaining how the ink ribbon descends.

FIG. 10 is a diagram illustrating a winding state of an ink ribbon in a cassette.

[Explanation of symbols]

3 ... Thermal head, 3a ... Heating resistor, 4 ... Ink ribbon, 5 ... Ribbon cassette, 52 ... Platen having a substantially rectangular cross-sectional shape.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location B41J 33/52 35/04 Z B41J 25/28 Z (72) Inventor Sogeji Kitagishi 1 Higashitaga-cho, Hitachi, Ibaraki 1-chome, Hitachi Ltd. Taga Factory, Hitachi Ltd.

Claims (1)

[Claims] 1. A thermal head, a platen facing the thermal head, an ink ribbon holding solid ink on the surface, the thermal head mounted, and a transverse movement operation while pressing the ink ribbon against the transfer paper by the thermal head. In a thermal transfer printer equipped with a carriage for performing the above, the contact angle of the thermal head with respect to the platen is set corresponding to the amount of deviation between the center of the ink ribbon width and the print center, and the back tension is applied to the entire width of the ink ribbon. A thermal transfer printer characterized in that