JP4242178B2 - Thermal printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal printer, and more particularly to a thermal printer that prints on a print medium sandwiched between a thermal head and a platen roller.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a thermal printer having a thermal head having a heating element in a direction intersecting with the conveyance direction of the print medium and a platen roller at a position facing the heating element of the thermal head, between the thermal head and the platen roller. The printing medium is conveyed by driving the platen roller while sandwiching the printing medium, and arbitrary information is printed on the printing medium by the heating action of the heating element of the thermal head. At this time, the thermal head is pressed against the platen roller with a predetermined pressing force by a biasing force of a spring provided on the head support member.
However, when printing on different types of printing media, for example, labels or tags, the printing pressure on the platen roller from the thermal head changes because the thickness and hardness of the printing media are different. There was a problem that a suitable print could not be obtained and the print was blurred or crushed.
[0003]
Here, the relationship between the printing medium and the printing pressure on the thermal head and the platen roller will be described with reference to FIGS.
4 and 5 are views showing a state in which the print head 45 is pressed against the platen roller 40 via a tag 50 or a label 51 as a print medium. As shown in FIG. 4A, the printing unit 41 has a platen roller 40 and a print head 45 provided mainly at a position facing the platen roller 40. The print head 45 has a heating element 44 and is fixed to a head holding plate 43 that can be rotated around a head support shaft 42. A tag 50 is sandwiched between the print head 45 and the platen roller 40, and the head is held. The print head 45 is pressed toward the platen roller 40 with a predetermined pressing force F by an elastic member 46 provided above the plate 43. Since the tag 50 has a relatively large hardness and a large thickness, the pressing force F from the elastic member 46 is increased, and the heating element 44 is more than the central vertical line 47 of the platen roller 40 as shown in FIG. Is positioned on the downstream side with respect to the sheet conveying direction, the rotational force f of the platen roller 40 is applied to the heating element 44 as a printing pressure, and good printing quality can be obtained. On the other hand, when the tag 50 having a relatively large hardness and a large thickness is used, the heating element 44 is located upstream of the central vertical line 47 of the platen roller 40 with respect to the sheet conveying direction as shown in FIG. The rotational force f is not applied to the heating element 44 as a printing pressure, and the printing pressure is reduced, which causes a decrease in printing quality such as fading.
[0004]
FIG. 5 is an explanatory diagram showing an example in which a label 51 is used as a print medium. Since the label 51 is relatively smaller in hardness than the tag 50 and has a small thickness, the pressing force F from the elastic member 46 is weakened, and the label 51 is removed from the central perpendicular 47 of the platen roller 40 as shown in FIG. However, if the heating element 44 is positioned downstream of the transport direction, the label 51 does not contact the heating element 44 due to the weak hardness, and the rotational force f of the platen roller 40 is applied to the heating element 44 as a printing pressure. In other words, it was a cause of printing quality deterioration such as fading. Further, as shown in FIG. 5B, the heating element 44 is positioned on the central vertical line 47 of the platen roller 40, or more upstream than the central vertical line 47 of the Latin roller 40 with respect to the conveyance direction of the print medium. When positioned, the rotational force f of the platen roller 40 is applied as a printing pressure to the heating element 44, and good printing quality can be obtained.
[0005]
As described above, when using a printing medium having a relatively large hardness and thickness, such as the tag 50, the heating element 44 of the thermal head 45 is located downstream of the central vertical line 47 of the platen roller 40 in the transport direction. In the case where a printing medium having a relatively small hardness and a small thickness such as the label 51 is used, the heating element 44 of the thermal head 45 is connected to the center perpendicular line of the platen roller 40. By placing the upper side 47 or upstream of the central perpendicular 47 with respect to the print medium conveyance direction and weakening the pressing force F, good print quality can be obtained for each print medium.
Therefore, manual adjustments such as moving the thermal head by loosening the tightening screw of the thermal head, or providing an eccentric cam on the thermal head mounting bracket, and rotating the eccentric cam, A positioning mechanism for a thermal head for printing that enables the head to be moved and adjusted is known (for example, see Patent Document 1).
[0006]
[Patent Document 1]
Actual Japanese Utility Model 1-175826 (Fig. 1)
[0007]
[Problems to be solved by the invention]
However, in the above-mentioned patent document, when the printing medium is thick paper, the printing pressure due to the rotational force f of the platen roller changes by adjusting the movement of the thermal head to the downstream side with respect to the transport direction, but the thermal head changes from the thermal head to the platen roller. The pressing force F in the heading direction requires manual adjustment such as tightening a screw.
Such manual adjustment is complicated and requires time to adjust the pressing force to the optimum value, and there is a problem that print blur or print blur occurs due to an adjustment error. In other words, when printing is performed on a printing medium having a large hardness and a thickness, if the pressing force F is adjusted to be lower than the optimum value, a blurring of printing occurs, and printing is performed on a printing medium having a small hardness and a small thickness. When the pressing force F is adjusted to be higher than the optimum value, there is a problem that printing blur occurs and wear of the heating element of the thermal head is accelerated.
A thermal printer that can easily adjust the rotational force and pressing force suitable for the type of print medium by moving the print head upstream or downstream in the transport direction with respect to the long hole provided in the thermal printer. It is to provide.
[0008]
[Means for Solving the Problems]
Thermal printer according to the present invention, there is provided a thermal printer for printing on a print medium by heating action of the heating element of supplying a printing medium to the printing unit print head having a print head and the platen roller, hold the print head It has a head holding plate for, provided on one end side of the head holding plate, and Ruhe head support shaft to support the head holding plate rotatably, a long hole that can slide the head support shaft An intermediate frame, an inclined member that is fixed above the head holding plate and has an inclined surface, and a pressing member that presses the inclined surface toward the platen roller.
Further, the inclined surface is characterized Life has name low <br/> gradually in height towards the downstream side with respect to the conveying direction of the print medium.
A fixing member that fixes the head support shaft to the long hole may be provided.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view of a thermal printer 1 according to an embodiment of the present invention. As shown in the figure, the thermal printer 1 includes a supply unit 2 that rotatably supports a printing medium 8 wound in a roll shape, a light emitting unit that emits predetermined light, and light emitted from the light emitting unit. And a sensor 3 for detecting the position of the print medium 8 based on the amount of light received by the light receiving unit, and a light receiving unit that outputs an electrical signal corresponding to the intensity of the received light (the amount of light received per unit time). The printing unit 4 that conveys and prints the printing medium 8 and the control unit 5 are provided.
[0010]
The printing unit 4 includes a platen roller 7 that conveys the print medium 8 leftward in FIG. 1 by driving a connected motor (not shown), and a print head 6 that presses the print medium 8 toward the platen roller 7. Thus, each part is controlled by the control unit 5 to heat the heating element 11 of the print head 6 described later, thereby printing on the print medium 8.
[0011]
FIG. 2 is a side view of a principal part in which the print head 6 of the thermal printer 1 of FIG. 1 is pressed against the platen roller 7. FIG. 3 shows the print head 6 of FIG. 2 as a platen roller (not shown). FIG. The printing unit and the pressing mechanism will be described with reference to FIGS.
[0012]
As shown in FIG. 2, the print head 6 has a heating element 11 disposed in a direction intersecting the conveyance direction of the print medium, and is fixed to the head holding plate 12. A head support shaft 13 that rotatably supports the print head 6 is provided on one end side of the head holding plate 12, and is provided with respect to a long hole 15 provided in the intermediate frame 14 of the thermal printer 1 shown in FIG. It is slidably provided. Further, it can be positioned at an arbitrary position of the long hole 15 by a fixing screw 16 provided at the end of the head support shaft 13. The long hole 15 has a shape that becomes longer in the paper conveyance direction.
[0013]
An inclined member 21 that adjusts the pressing force F from the print head 6 toward the platen roller 7 is fixed above the head holding plate 12. As shown in FIGS. 2 and 3, the inclined member 21 has an inclined surface 26 whose height gradually decreases toward the downstream side in the conveyance direction of the print medium 8.
Further, two pressing blocks 23 and 24 (pressing members) that press the inclined surface 26 toward the platen roller 7, and a rotating shaft 22 that fixes the two pressing blocks 23 and 24 at a predetermined interval; A pressing mechanism 20 is provided on one end side of the rotating shaft 22 and includes an opening / closing lever 25 that rotates the pressing blocks 23 and 24.
[0014]
The pressing blocks 23 and 24 are fixed to the rotating shaft 22 by a C ring or E ring (not shown) at a predetermined interval from each other. The pressing blocks 23 and 24 have springs (not shown), and press the print head 6 with a predetermined pressing force F by an urging force applied in the direction toward the platen roller 7 as shown in FIG.
[0015]
The opening / closing lever 25 is fixed to one end of the rotation shaft 22, and the rotation shaft 22 and the pressing blocks 23, 24 are interlocked by rotating the opening / closing lever 25 in the clockwise direction (the arrow direction shown in FIG. 3). Then, the print head 6 is locked by rotating in the clockwise direction and the tip of the opening / closing lever 25 coming into contact with a locking member (not shown) provided in the printer main body.
The print head 6 is provided with a coil spring (not shown) so as to urge upward, and the pressing blocks 23 and 24 return to the positions shown in FIG. 3 by turning the open / close lever 25 counterclockwise. At the same time, the print head 6 is also moved upward by the coil spring.
[0016]
Next, a printing pressure adjustment method for the thermal printer 1 according to an embodiment of the present invention will be described with reference to FIGS. 2 and 3. First, when a tag (not shown) having a large thickness and a large hardness is used as a printing medium, for example, the head support shaft 13 is located downstream of the long hole 15 in the paper conveyance direction (left in FIG. 2). 2), the fixing screw 16 is tightened and fixed to the intermediate frame 14, the opening / closing lever 25 is rotated clockwise through the tag between the platen roller 7 and the print head 6, and the print head 6 is rotated at the virtual position in FIG. Lock. At this time, the heating element 11 of the print head 6 is positioned on the downstream side with respect to the sheet conveying direction with respect to the central perpendicular of the platen roller 7, and the rotational force f by the platen roller 7 is printed on the heating element 11. It comes to be added as pressure.
[0017]
Further, as the head support shaft 13 is moved, the inclined member 21 is also positioned at the virtual position in FIG. 2, and in this state, the opening / closing lever 25 is rotated in the clockwise direction so that the pressing blocks 23 and 24 are inclined to the inclined surface 26 of the inclined member 21. , The heat generating element 11 of the print head 6 is pressed toward the platen roller 7 with a predetermined pressing force F via the inclined surface 26 by pressing blocks 23 and 24 having springs (not shown). Therefore, the rotational force f and the pressing force F are applied as the printing pressure to the tag and the heating element 11, and the tag can be printed with high quality by the heating action of the heating element 11 of the print head 6.
[0018]
On the other hand, when a label (not shown) having a small thickness and a low hardness is used as the print medium, the head support shaft 13 is moved in the direction opposite to the sheet conveyance with respect to the long hole 15 and the fixing screw 16 is tightened. Then, it is fixed to the intermediate frame 14, and the opening / closing lever 25 is rotated clockwise through a label between the platen roller 7 and the print head 6 to lock the print head 6 at the solid line position in FIG. At this time, the heating element 11 of the print head 6 is positioned on the upstream side in the transport direction with respect to the center perpendicular of the platen roller 7, and an appropriate rotational force f by the platen roller 7 is applied to the label. It is added as printing pressure.
[0019]
Further, as the head support shaft 13 moves, the inclined member 21 also moves in the reverse direction of the sheet conveyance (right direction in FIG. 2) and is positioned at the solid line position in FIG. 2, and in this state, the open / close lever 25 is rotated clockwise. By moving, the pressing blocks 23, 24 are brought into contact with the inclined surface 26 of the inclined member 21. Pressing blocks 23 and 24 having springs (not shown) press the heating element 11 of the print head 6 toward the platen roller 7 with a predetermined pressing force F via the inclined surface 26. Therefore, the rotational force f and the pressing force F are applied as the printing pressure on the label, and high-quality printing can be performed on the label by the heating action of the heating element 11 of the print head 6.
[0020]
As described above, when printing on a printing medium such as a tag having a large thickness and a high hardness, the heating element 11 is positioned with respect to the platen roller 7 by a small amount on the downstream side in the transport direction. Further, the rotational force f by the platen roller 7 applied to the heating element 11 is increased, and the inclined member 21 is also moved to the downstream side with respect to the conveying direction, so that the height of the inclined surface 26 contacting the pressing blocks 23 and 24 is increased. The pressure F increases toward the platen roller 7 by the pressing blocks 23 and 24 and increases. Accordingly, in the case of a printing medium such as a tag having a large thickness and a high hardness, the printing pressure, which is the rotational force f and the pressing force F, is increased, and the heat generated by the heat generating action of the heating element 11 is reliably transmitted to the printing medium. Can be surely prevented from fading.
[0021]
On the other hand, when printing on a printing medium such as a label having a small thickness and a low hardness, the heating element 11 is added to the heating element 11 by positioning the heating element 11 with respect to the platen roller 7 in the reverse direction of the sheet conveyance. The rotational force f by the platen roller 7 is reduced, and the inclined member 21 is also moved in the reverse direction of the sheet conveyance, and the height of the inclined surface 26 contacting the pressing blocks 23 and 24 is lowered. The pressing force F toward the roller 7 is reduced. Therefore, in the case of a printing medium such as a label having a small thickness and a low hardness, the printing pressure, which is the rotational force f and the pressing force, can be reduced, and the heat generated by the heat generating action of the heating element 11 can be reliably transmitted to the printing medium. This can surely prevent printing bleeding.
[0022]
The printing system in the present invention may be a thermal printing system that prints on thermal paper processed with a thermal color former or a thermal transfer printing system that prints on paper using an ink ribbon.
Further, the tag has been described as an example of a printing medium having a large thickness and a high hardness, and a label has been described as an example of a printing medium having a small thickness and a low hardness. However, the present invention is not limited to this.
In addition, by setting a scale indicating the thickness of the printing medium in the vicinity of the long hole provided in the intermediate frame of the thermal printer, it is possible to easily set the printing pressure for the printing medium.
[0023]
【The invention's effect】
The head holding plate that holds the print head can be moved with respect to the long hole provided in the thermal printer, and the printing pressure on the heating element is optimized as the rotational force of the platen roller according to the thickness and hardness of the print medium to be used. Therefore, even if the type of the printing medium changes, it is possible to prevent printing fading or deterioration of printing quality due to printing blur.
Also, by providing the inclined member, it is possible to adjust the printing pressure applied to the heating element as the pressing force toward the platen roller according to the thickness, hardness, etc. of the printing medium to be used. Even if it is changed, it is possible to prevent deterioration in print quality such as fading.
In addition, by providing an inclined member having an inclined surface whose height gradually decreases toward the downstream side with respect to the conveyance direction of the print medium, printing is performed when a print medium having a large thickness and a large hardness is used. The rotational force and the pressing force can be easily adjusted simply by moving the head downstream with respect to the paper transport direction. Similarly, when a print medium having a small thickness and a low hardness is used, the print pressure, which is a rotational force and a pressing force, can be easily adjusted simply by moving the print head in the reverse direction of the paper conveyance.
Further, since the fixing member for fixing the head support shaft to the long hole of the intermediate frame is provided, the print head can be firmly fixed in the forward / reverse direction of the sheet conveyance.
[Brief description of the drawings]
FIG. 1 is a schematic side view of a thermal printer according to an embodiment of the present invention.
2 is an enlarged side view of the vicinity of a printing unit of the thermal printer in FIG. 1. FIG.
3 is a schematic perspective view of the vicinity of a printing unit in which the print head in FIG. 2 is in a retracted state with respect to a platen roller.
FIG. 4 is an explanatory diagram for explaining a printing pressure when a printing medium is a tag.
FIG. 5 is an explanatory diagram illustrating a printing pressure when a printing medium is a label.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Thermal printer 2 Supply part 3 Sensor 4 Printing part 5 Control part 6 Print head 7 Platen roller 8 Print medium 11 Heating body 12 Head holding plate 13 Head support shaft 14 Intermediate frame 15 Long hole 16 Fixing screw 20 Pressure adjustment mechanism 21 Inclination member 22 Rotating shaft 23 Press block 24 Press block 25 Open / close lever 40 Platen roller 41 Print head 42 Head support shaft 43 Head support plate 44 Heating element 45 Thermal head 46 Elastic member 47 Center perpendicular 50 Tag 51 Label

Claims (3)

A thermal printer that supplies a print medium to a print unit having a print head and a platen roller, and prints on the print medium by a heat generating action of a heat generating element of the print head,
A head holding plate for holding the print head,
Provided on one end side of the head holding plate, and Ruhe head support shaft to support the head holding plate rotatably,
An intermediate frame having a long hole that allows the head support shaft to slide;
An inclined member fixed above the head holding plate and having an inclined surface ;
And a pressing member that presses the inclined surface toward the platen roller. The inclined surface is a thermal printer according to claim 1, wherein the are I Do lower gradually in height towards the downstream side with respect to the conveying direction of the print medium. Furthermore, according to claim 1 or 2, wherein the thermal printer, characterized in that a fixing member for fixing the head support shaft with respect to the elongated hole.

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