JP2004255730A - Thermal printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal printer in which the print pressure can be adjusted suitably even if the thickness or hardness of a print medium is varied and degradation of print quality, e.g. blurring of a print, can be prevented. <P>SOLUTION: In the thermal printer for printing on a print medium held between a platen roller 7 and a print head 6 having a heating element 11, a rotating force f being applied to the heating element 11 can be adjusted by making a head supporting shaft 13 provided on one side of the print head 6 movable in the forward/reverse carrying direction of sheet with respect to an elongated hole 15 in an intermediate frame. Furthermore, a pressing force F directed toward the platen roller 7 can be adjusted by the inclining face 26 of an inclining member 21 provided above a head holding plate 12. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD 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]
Conventionally, in a thermal printer having a thermal head having a heating element in a direction intersecting with the transport direction of a print medium and a platen roller at a position opposed to the heating element of the thermal head, in a thermal printer, The print medium is conveyed by driving the platen roller while nipping the print medium, and arbitrary information is printed on the print medium by the heat generating action of the heating element of the thermal head. At this time, the thermal head presses the platen roller with a predetermined pressing force by the urging force of a spring provided on the head support member.
However, when printing on different types of print media, for example, labels or tags, the print pressure from the thermal head to the platen roller changes because the print media has different thicknesses, hardness, and the like. There is a problem in that suitable printing cannot be obtained, and print fading or printing collapse occurs.
[0003]
Here, the relationship between the printing medium and the printing pressure of the thermal head and the platen roller will be described with reference to FIGS.
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 mainly includes a platen roller 40 and a print head 45 provided 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 is rotatable about a head support shaft 42, a tag 50 is sandwiched between the print head 45 and the platen roller 40, The print head 45 is pressed by the elastic member 46 provided above the plate 43 with a predetermined pressing force F toward the platen roller 40. Since the tag 50 has a relatively high hardness and a large thickness, the pressing force F from the elastic member 46 is increased, and as shown in FIG. Is located downstream with respect to the sheet transport direction, the rotational force f of the platen roller 40 is applied to the heating element 44 as a printing pressure, so that good printing quality can be obtained. On the other hand, when the tag 50 having a relatively high hardness and a large thickness is used, as shown in FIG. 4B, the heating element 44 is located upstream of the center perpendicular 47 of the platen roller 40 with respect to the sheet transport direction. In this case, the rotational force f is not applied to the heating element 44 as the printing pressure, and the printing pressure is reduced, thereby causing print quality deterioration such as faint printing.
[0004]
FIG. 5 is an explanatory diagram showing an example in which a label 51 is used as a print medium. The label 51 has a relatively lower hardness than the tag 50 and a smaller thickness, so that the pressing force F from the elastic member 46 is weakened, and the label 51 is moved from the center perpendicular 47 of the platen roller 40 as shown in FIG. Also, when the heating element 44 is located on the downstream side in the transport direction, the label 51 does not come into contact with the heating element 44 due to the low hardness of the label 51, and the rotational force f of the platen roller 40 is applied to the heating element 44 as a printing pressure. However, the print quality was deteriorated such as blurred print. Further, as shown in FIG. 5B, the heating element 44 is located on the center perpendicular 47 of the platen roller 40 or on the upstream side of the center perpendicular 47 of the latin roller 40 in the transport direction of the print medium. When it is located, the rotational force f of the platen roller 40 is applied to the heating element 44 as a printing pressure, so that good printing quality can be obtained.
[0005]
As described above, when a relatively hard and thick print medium such as the tag 50 is used, the heating element 44 of the thermal head 45 is located downstream of the center perpendicular 47 of the platen roller 40 in the transport direction. Side, and the pressing force F is increased. On the other hand, when a printing medium having a relatively small hardness and a small thickness such as a label 51 is used, the heating element 44 of the thermal head 45 is connected to the center perpendicular to the platen roller 40. By setting the pressing force F to a lower position on the printing medium transport direction above the printing medium 47 or the center perpendicular 47 and to obtain a good printing quality for each printing medium.
Therefore, manually adjusting the thermal head by moving the thermal head by loosening the tightening screw of the thermal head, providing an eccentric cam on the mounting bracket of the thermal head, and rotating the eccentric cam to move the thermal head upstream or downstream in the paper transport direction 2. Description of the Related Art A positioning mechanism for a printing thermal head that allows a head to be moved and adjusted is known (for example, see Patent Document 1).
[0006]
[Patent Document 1]
No. 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 moving and adjusting the thermal head to the downstream side in the transport direction. The pressing force F in the heading direction requires manual adjustment such as tightening of a screw.
Such manual adjustment is complicated and takes time to adjust the pressing force to the optimum value. In addition, there is a problem that printing misalignment or blurring of printing occurs due to an adjustment error. That is, 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, the printing may be blurred, and printing may be 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 when applying, there is a problem that printing bleeding occurs and wear of the heating element of the thermal head is accelerated.
By moving the print head upstream or downstream in the transport direction with respect to the slot provided in the thermal printer, a thermal printer that can easily adjust the rotational force and pressing force suitable for the type of print medium To provide.
[0008]
[Means for Solving the Problems]
A thermal printer according to a first aspect of the present invention is 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 heating action of a heating element of the print head. A head holding plate for holding the head, a head supporting shaft for rotatably supporting the head holding plate and movably supporting the head holding plate with respect to a long hole provided in the thermal printer; It has a tilt member fixed to the head holding plate, and a pressing member for pressing the tilt member in the direction of the platen roller.
Further, the inclined member may have an inclined surface whose height gradually decreases toward the downstream side in the transport direction of the print medium.
Further, a fixing member for fixing the head support shaft to the elongated hole may be provided.
[0009]
BEST MODE FOR CARRYING OUT 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 FIG. 1, the thermal printer 1 includes a supply unit 2 that rotatably supports a print medium 8 wound in a roll shape, a light emitting unit that emits predetermined light, and a light that is 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 receiving an electric signal corresponding to the intensity of the received light (the amount of light received per unit time). A printing unit 4 for transporting and printing the printing medium 8, and a control unit 5.
[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. The printing is performed on the print medium 8 by controlling each unit by the control unit 5 and causing a heating element 11 of the print head 6 to be described later to generate heat.
[0011]
FIG. 2 is a side view of a main part of the thermal printer 1 shown in FIG. 1 in a state where the print head 6 is pressed against a platen roller 7, and FIG. 3 is a view showing the print head 6 shown in FIG. 2 as a platen roller (not shown). FIG. 4 is a perspective view of a main part in a retracted state with respect to 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 arranged in a direction intersecting the transport direction of the print medium, and is fixed to a head holding plate 12. At one end of the head holding plate 12, a head support shaft 13 for rotatably supporting the print head 6 is provided, and the head support shaft 13 is provided with a long hole 15 provided in an intermediate frame 14 of the thermal printer 1 shown in FIG. It is slidably provided. Further, a fixing screw 16 provided at an end of the head support shaft 13 enables positioning at an arbitrary position of the long hole 15. The long hole 15 has a shape that becomes longer in the paper transport direction.
[0013]
Above the head holding plate 12, an inclined member 21 for adjusting a pressing force F from the print head 6 toward the platen roller 7 is fixed. The inclined member 21 has an inclined surface 26 whose height gradually decreases toward the downstream side in the transport direction of the print medium 8 as shown in FIGS.
Further, two pressing blocks 23 and 24 (pressing members) for pressing the inclined surface 26 toward the platen roller 7, a rotating shaft 22 having the two pressing blocks 23 and 24 fixed at a predetermined interval, and A pressing mechanism 20 is provided at one end of the rotating shaft 22 and includes an opening / closing lever 25 for rotating the pressing blocks 23 and 24.
[0014]
The pressing blocks 23 and 24 are fixed to the rotation shaft 22 by a C ring or an 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 a direction toward the platen roller 7 as shown in FIG.
[0015]
The opening / closing lever 25 is fixed to one end of the rotating shaft 22, and by rotating the opening / closing lever 25 clockwise (the direction of the arrow shown in FIG. 3), the rotating shaft 22 and the pressing blocks 23 and 24 are interlocked. Then, the print head 6 is locked when the tip of the opening / closing lever 25 comes into contact with a locking member (not shown) provided on the printer main body.
The print head 6 is provided with a coil spring (not shown) so as to urge the print head 6 upward. When the open / close lever 25 is rotated counterclockwise, the pressing blocks 23 and 24 return to the positions shown in FIG. At the same time, the print head 6 is also moved upward by the coil spring.
[0016]
Next, a method for adjusting the printing pressure of the thermal printer 1 according to an embodiment of the present invention will be described with reference to FIGS. First, when a tag (not shown) having a large thickness and a high hardness is used as a print medium, for example, the head support shaft 13 is positioned downstream of the slot 15 with respect to the paper transport direction (left side in FIG. 2). 2), the fixing screw 16 is tightened and fixed to the intermediate frame 14, and the opening / closing lever 25 is rotated clockwise through the tag between the platen roller 7 and the print head 6 to rotate the print head 6 at the virtual position in FIG. To lock. At this time, the heating element 11 of the print head 6 is positioned slightly downstream with respect to the center line of the platen roller 7 with respect to the sheet conveyance direction, and the rotational force f of the platen roller 7 is applied to the heating element 11 by printing. It is applied as pressure.
[0017]
In addition, with the movement of the head support shaft 13, the inclined member 21 is also located at the virtual position in FIG. 2. In this state, the opening / closing lever 25 is rotated clockwise to push the pressing blocks 23 and 24 to the inclined surface 26 of the inclined member 21. , The heating element 11 of the print head 6 is pressed by the pressing blocks 23 and 24 having springs (not shown) through the inclined surface 26 toward the platen roller 7 with a predetermined pressing force F. Therefore, the rotational force f and the pressing force F are applied as printing pressure to the tag and the heating element 11, and high quality printing can be performed on the tag 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 small hardness is used as a print medium, for example, the head support shaft 13 is moved with respect to the long hole 15 in the reverse direction of the sheet conveyance, and the fixing screw 16 is tightened. The print head 6 is locked at the solid line position in FIG. 2 by rotating the opening / closing lever 25 clockwise through the label between the platen roller 7 and the print head 6. At this time, the heating element 11 of the print head 6 is positioned slightly upstream with respect to the transport direction with respect to the center perpendicular line of the platen roller 7, and an appropriate rotational force f by the platen roller 7 is applied to the label. It is applied as printing pressure.
[0019]
Further, with the movement of the head support shaft 13, the inclined member 21 also moves in the reverse direction (rightward in FIG. 2) in the sheet conveyance, and is positioned at the solid line position in FIG. 2, and in this state, the open / close lever 25 is turned clockwise. By moving, the pressing blocks 23 and 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 via the inclined surface 26 with a predetermined pressing force F. Therefore, the rotational force f and the pressing force F are applied as printing pressure to the label, and high-quality printing can be performed on the label by the heat generating action of the heating element 11 of the print head 6.
[0020]
As described above, when printing is performed on a printing medium such as a tag having a large thickness and a high hardness, the position of the heating element 11 with respect to the platen roller 7 is positioned by a very small amount on the downstream side in the transport direction. The rotational force f of the platen roller 7 applied to the heating element 11 increases, and the height of the inclined surface 26 that contacts the pressing blocks 23 and 24 is increased by moving the inclined member 21 downstream with respect to the transport direction. As a result, the pressing force F applied to the platen roller 7 by the pressing blocks 23 and 24 increases. Accordingly, in the case of a printing medium such as a tag having a large thickness and a high hardness, the printing force, which is the rotational force f and the pressing force F, is increased, so that the heat generated by the heating element 11 can be reliably transmitted to the printing medium. Can be surely prevented from being blurred.
[0021]
On the other hand, when printing is performed on a printing medium such as a label having a small thickness and a small 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 by a very small amount in the reverse direction of the sheet conveyance. The rotational force f by the platen roller 7 decreases, and the inclined member 21 also moves in the reverse direction of the sheet conveyance, so that the height of the inclined surface 26 abutting on the pressing blocks 23 and 24 decreases. The pressing force F toward the roller 7 decreases. Therefore, in the case of a printing medium such as a label having a small thickness and a small hardness, it is possible to reduce the rotational force f and the printing pressure, which is the pressing force, to surely transfer the heat generated by the heating element 11 to the printing medium. Can be surely prevented from blurring in printing.
[0022]
The printing method in the present invention may be a thermal printing method for printing on thermal paper treated with a thermal coloring agent or a thermal transfer printing method for printing on paper using an ink ribbon.
Further, the tag has been described as an example of a print medium having a large thickness and high hardness, and a label has been described as an example of a print medium having a small thickness and low hardness. However, the present invention is not limited to this.
Further, by providing a scale indicating the thickness of the print medium near the long hole provided in the intermediate frame of the thermal printer, it is possible to easily set the print pressure on the print 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 applied to the heating element as the rotational force of the platen roller is optimized according to the thickness, hardness, etc. of the printing medium used The print quality can be adjusted to an appropriate value, and even if the type of print medium changes, it is possible to prevent the print quality from being blurred or blurred.
In addition, by providing the inclined member, the printing pressure applied to the heating element as the pressing force toward the platen roller can be adjusted to an optimum value according to the thickness, hardness, etc. of the printing medium to be used, and the type of printing medium can be adjusted. Even if the print quality changes, it is possible to prevent a decrease in print quality such as blurred print.
In addition, by providing an inclined member having an inclined surface whose height gradually decreases toward the downstream side with respect to the transport direction of the print medium, printing is performed when a thick and hard print medium is used. The rotational force and the pressing force can be easily adjusted only by moving the head downstream with respect to the sheet transport direction. Similarly, when a print medium having a small thickness and a small hardness is used, the rotational pressure and the printing pressure, which is the pressing force, can be easily adjusted only by moving the print head in the reverse direction of the sheet 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 and reverse directions 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.
FIG. 2 is an enlarged side view of the vicinity of a printing portion of the thermal printer in FIG.
FIG. 3 is a schematic perspective view of the vicinity of a printing unit when a print head in FIG. 2 is retracted from a platen roller.
FIG. 4 is an explanatory diagram illustrating 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]
REFERENCE SIGNS LIST 1 thermal printer 2 supply unit 3 sensor 4 printing unit 5 control unit 6 print head 7 platen roller 8 print medium 11 heating element 12 head holding plate 13 head support shaft 14 intermediate frame 15 long hole 16 fixing screw 20 pressure adjusting mechanism 21 inclined member 22 rotating shaft 23 pressing block 24 pressing block 25 opening / closing 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 heating action of a heating element of the print head,
A head holding plate for holding a print head,
A head support shaft that rotatably supports the head holding plate and movably supports the head holding plate with respect to a long hole provided in the thermal printer;
An inclined member fixed to the head holding plate,
A pressing member for pressing the inclined member in the direction of the platen roller,
A thermal printer comprising: 2. The thermal printer according to claim 1, wherein the inclined member has an inclined surface whose height gradually decreases toward the downstream side with respect to the transport direction of the print medium. 2. The thermal printer according to claim 1, further comprising a fixing member for fixing the head support shaft to the slot.

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