JP3661357B2 - Thermal printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a small line thermal printer used for electronic equipment such as a receipt issuing machine.
[0002]
[Prior art]
Conventionally, small electronic line thermal printers have been widely used in electronic devices such as receipt issuing machines. In the case of a thermal printer, the thermal head is pressed against the platen roller. If this pressing load is too small, the printing becomes thin, and if the pressing load is large, the load on the mechanism is large and the durability may be impaired. Generally, this important pressing load is given by a spring member. However, when the spring member is assembled to the printer, it is necessary to apply a stronger force to the spring than when it is operated to deform the spring. Therefore, conventionally, it has been difficult to detach and attach the spring member. Therefore, as disclosed in Japanese Utility Model Laid-Open No. 1-156041, a technique for facilitating attachment / detachment of the spring member has been proposed. The technique described in the above publication is a technique in which the biasing force applied to the spring is changed by a screw and a spring holding member so that the biasing force does not act on the spring and then the spring is detached.
[0003]
[Problems to be solved by the invention]
However, such a conventional technique has the following problems although it is easy to attach and detach the spring member.
[0004]
That is, since a separate part for changing the urging force of the spring is required, the mechanism itself becomes complicated, which naturally increases the cost.
[0005]
Furthermore, the load accuracy is easily affected by the presence of another part.
[0006]
The present invention has been made in order to solve the problems of the prior art, and the object of the present invention is a thermal printer with good head pressing load accuracy and a complicated separate part. It is an object of the present invention to provide a thermal printer that is easy to detach and attach a spring member for pressing the head without being provided, and that is easy to assemble and replace.
[0007]
[Means for Solving the Problems]
Thermal printer of the present invention for achieving the above object is rotatably supported on the frame supporting the support Maruheddo, a head fixing plate having a re blanking in the longitudinal direction and a position of substantially parallel the platen, both ends arm portion and having a torsion coil spring for urging the head fixing plate engaged with Li blanking to the platen side.
[0008]
According to the above arrangement, even if somewhat the shape and mounting position of the torsion coil spring varies, the biasing force of the torsion coil spring is always to be added to the rib, the load accuracy is stabilized.
[0009]
Further, the torsion coil spring, the coil portion is supported through a support shaft supported in the frame, the arm portion of both ends engage the re blanking, the arm of the central portion is formed by bending a frame It is a torsion coil spring of a double torsion spring shape that engages with the support portion .
[0010]
According to the above configuration, since the support shaft is disposed so as to penetrate the coil portion of the torsion coil spring, the torsion coil spring is detached from the support shaft even when the engagement between the torsion coil spring and the support portion is released. There is no end to it. Further, since the load is applied at two locations on the arm portions at both ends, it is easy to apply a uniform load in the line direction.
[0011]
Furthermore, the torsion coil spring can be moved in the axial direction of the support shaft by releasing the engagement of the support portion.
[0012]
According to the above configuration, the torsion coil spring can be passed through the support shaft in a state where the torsion coil spring is not deformed with a strong force.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of a thermal printer according to the present invention will be described below in detail with reference to FIGS.
[0014]
FIG. 1 is a plan view showing the overall configuration of the thermal printer according to the present embodiment, and FIG. 2 is a side view showing the configuration of the printing portion, in which the thermal head presses the platen roller by tilting the lever member. FIG. 3 is a perspective view of the thermal printer at that time. FIG. 4 is a perspective view showing a state during the assembly of the printer, specifically, a state before the spring member for pressing the head is set at a predetermined position.
[0015]
As shown in FIG. 1, a thermal printer 1 according to the present embodiment has a main body frame 2 made of a sheet metal press member such as a plated steel plate. The main body frame 2 includes a printing unit 3, a platen roller 4, and a platen. A drive motor 5 for driving the roller 4 is attached.
[0016]
The main body frame 2 is formed by bending a bottom portion 2c and a pair of side wall portions 2a, 2b by sheet metal processing. A paper guide portion 21 to be described later is formed on the rear side of the main body frame 2. The spring support 2d is formed by being bent from the bottom 2c of the main body frame 2. Therefore, the hole 2e is opened beside the spring support 2d.
[0017]
The printing unit 3 includes a thermal head 30 and a fixed plate 31. A predetermined electrode is formed on the surface of the thermal head 30, and this electrode is connected to a circuit board (not shown). The thermal head 30 is bonded and fixed to, for example, a long flat plate-like fixing plate 31 made of a metal such as a soft iron plate with a double-sided tape or the like.
[0018]
The fixed plate 31 is formed with ribs 31 d having a length substantially equal to that of the platen roller 4 in parallel to the axial direction of the platen roller 4, that is, in the line direction. The rib 31d has a semicircular cross-sectional shape as shown in FIG. 2, and the same cross-sectional shape over the entire length of the rib 31d. The ribs 31d are formed by half punching pressing of the fixed plate 31. The rib 31d increases the rigidity of the fixing plate 31 in the line direction and is difficult to deform.
[0019]
Therefore, by providing this rib 31d, the fixing plate 31 can be made of a thinner material than before. Further, the fixing plate 31 is formed by bending arm portions 31 a and 31 b at both ends thereof so as to have a width substantially equal to the inner width of the main body frame 2. The arm portions 31 a and 31 b are rotatably attached to a support shaft 6 that is spanned in parallel with the platen roller 4 on both side portions of the main body frame 2.
[0020]
Further, a torsion coil spring 7 for the thermal head 30 to press the platen roller 4 is attached to the support shaft 6. In this case, as shown in FIG. 1, the torsion coil spring 7 is a double torsion spring having a substantially U-shaped engaging portion 7a at an intermediate portion and arm portions 7b and 7c formed on both sides thereof. I am doing. The support shaft 6 is configured to penetrate through the coil portion of the torsion coil spring 7, and the arm portions 7d and 7e are urged at predetermined intervals to the rib 31d formed on the fixed plate 31, The engaging portion 7a is biased and locked to a spring support portion 2d provided by bending from the bottom portion 2c of the main body frame 2.
[0021]
As a result, as shown in FIG. 2, the thermal head 30 is pressed from above toward the platen roller 4. Note that the spring hooking position of the support portion 2d is higher than the bottom portion 2c of the frame 2, and when the engagement between the torsion coil spring 7 and the support portion 2d is released, the engagement portion 7a of the torsion coil spring 7 becomes the frame. The biasing force applied to the torsion coil spring 7 is weakened by moving to the bottom 2c side.
[0022]
This embodiment is characterized in that the pressing force of the thermal head 30 against the platen roller 4 is obtained by the torsion coil spring 7 coming into contact with the rib 31d, and the torsion coil spring 7 has a certain shape due to processing problems. Even if it varies, the point to apply the urging force is determined and the load accuracy is improved. Further, in the present embodiment, a double torsion spring is used, and the thermal head 30 is pressed against the platen roller 4 evenly in the line direction because the load is urged evenly at the two left and right positions. The Therefore, there is no defect that one side in the line direction becomes thin due to the contact of the thermal head.
[0023]
In addition, a protruding portion 31 c that engages with the guide portion 80 of the lever member 8 to cause the fixing plate 31 is integrally formed at the end of the fixing plate 31 on the lever member 8 side. The protruding portion 31 c is formed with a tongue-like portion so as to protrude from one side wall portion 2 b of the main body frame 2, and the tongue-like portion is bent to the side opposite to the fixed side of the thermal head 30. It is formed.
[0024]
On the other hand, the platen roller 4 is rotatably attached to both side walls 2a and 2b of the main body frame 2 via platen bearings 41a and 41b. As shown in FIG. 1, the torque of the rotating shaft 50 of the drive motor 5 is transmitted to the gear 9 fixed to one end of the platen shaft 40 of the platen roller 4 via the gears 10, 11, and 12. Configured to be The drive motor 5 is connected to a circuit board (not shown) via a lead wire 51 and a connector 52.
[0025]
At the other end of the platen roller 4, a lever member 8 for switching the pressing or releasing of the thermal head 30 against the platen roller 4 is rotatably attached. When the lever member 8 is operated, the protruding portion 31 c of the fixing plate 31 and the cam portion 80 formed on the lever member 8 are engaged with each other, and the fixing plate 31 is caused to move between the thermal head 30 and the platen roller 4. There is a gap.
[0026]
On the rear side of the bottom portion 2 c of the main body frame 2, a paper guide portion 21 for guiding the roll paper S, in which the thermal recording paper is wound in a cylindrical shape, to the contact position between the thermal head 30 and the platen roller 4, is the bottom portion 2 c. It is formed by curving a part of.
[0027]
By introducing the paper guide portion 21 to the platen roller 4 side, an introduction portion 21a along the shape of the platen roller 4 is formed. In this case, the end portion 21c of the introduction portion 21a is configured to enter the contact portion between the thermal head 30 and the platen roller 4, that is, the vicinity of the printing position.
[0028]
On the other hand, as shown in FIG. 1, groove portions 24 and 25 are formed on both sides of the rear end portion of the paper guide portion 21, and the platen roller 4 is formed between the groove portions 24 and 25. Bending portions 21b are formed so as to protrude to the side. The bend raising portion 21b is substantially parallel to the platen roller 4, that is, extends in the width direction of the roll paper S, and has a substantially mountain-like cross section by bending, for example, and serves as an inlet portion for the roll paper S. Yes. This bending raising portion 21d secures a predetermined platen winding angle and prevents the roll paper S from slipping when the roll paper S is tensioned due to the load of the paper path to the roll paper S supply unit and the printer entrance. There is a role to prevent. Further, the width of the frame side wall portions 2a and 2b is slightly larger than the width of the roll paper S, and the frame side wall portions 2a and 2b serve as guides for regulating the width direction of the roll paper S.
[0029]
Next, assembly of the thermal printer 1 will be described. First, when assembling the platen roller 4, the lever member 8, the drive motor 5, and the like to the main body frame 2, when assembling the printing unit 3 including the thermal head 30 and the fixed plate 31, the support shaft 6 is fixed to the fixed plate. 31 and the torsion coil spring 7 and span the left and right side walls 2 a and 2 b of the main body frame 2. Then, the state shown in FIG. 4 is obtained. At this time, it is not necessary to apply a force against the spring force to the torsion coil spring 7, it is only necessary to pass it through the support shaft 6, and the operation is easy. The torsion coil spring 7 is movable in the axial direction around the support shaft 6 and is not firmly fixed. That is, it is a temporarily fixed state. From the state shown in FIG. 4, the assembly operator pulls up the engaging portion 7 a of the torsion coil spring 7 and slides the torsion coil spring 7 slightly in the axial direction, while hanging on the spring support portion 2 d provided on the main body frame 2. Stop. This completes the assembly of the printer. This state is shown in FIG.
[0030]
In general, in the assembly of a thermal printer, it is the most difficult work to assemble a spring member for pressing the head. In this embodiment, the spring member can be latched in the final process of assembly. When the member is latched, the structure is such that the torsion coil spring 7 can be slid by using the support shaft 6 as a guide. Therefore, the operation of latching the engaging portion 7a on the spring support portion 2d is easy. Further, the spring member does not come off when the spring member is hooked.
[0031]
Further, in the present embodiment, since the hole 2e is opened on the bottom of the printer next to the spring support 2d, the spring can be latched even by passing a tool from the bottom of the printer to the hole 2e. This is particularly effective in the case where work from the upper part of the printer cannot be performed or is difficult due to, for example, an auto cutter unit or the like disposed on the upper part of the printer.
[0032]
As described above, the thermal printer of this embodiment has good load accuracy of the head pressing, which greatly affects the print quality and the reliability of the printer, and also has a good assembly of the printer.
[0033]
【The invention's effect】
According to the present invention, as described in claim 1, the configuration of the torsion coil spring and the mounting position of the torsion coil spring is configured such that the arm portion of the torsion coil spring abuts against the rib of the fixing plate and presses the thermal head against the platen. Even if there is some variation, the pressing load is accurately determined, and a thermal printer with high print quality and reliability can be obtained.
[0034]
Further, when configured as described in claims 2 and 3, when applying a force to the torsion coil spring and detaching it from the support portion, the spring does not spring out and jump out, and it has excellent workability and thermal performance. It is possible to provide a thermal printer in which the print quality is improved with no head contact.
[0035]
Further, since the torsion coil spring can be hooked or removed from the support portion while the torsion coil spring is slid in the axial direction, the spring hooking operation is facilitated. The improved workability of the spring hook is not only effective in manufacturing the printer at the factory, but also effective when the thermal head is replaced after service.
[0036]
As described above, the present invention provides a thermal printer that has an extremely simple structure and excellent print quality and assembly workability.
[Brief description of the drawings]
FIG. 1 is a plan view showing the overall configuration of an embodiment of a thermal printer according to the present invention.
FIG. 2 is a side view showing a configuration of a printing portion in the same embodiment, showing a state in which a lever member is tilted.
FIG. 3 is a perspective view of the thermal printer in the same embodiment.
FIG. 4 is a perspective view showing a state during assembly in the same embodiment;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Thermal printer 2 Main body frame 2a, 2b Side wall part 2c Bottom part 21 Paper guide part 21a Introduction part 21b Bending part 21c Tip part 3 Printing part 30 Thermal head 31 Fixing plate 4 Platen roller 5 Drive motor 7 Torsion coil spring 8 Lever member S Roll paper

Claims (1)

A thermal head for printing on a recording paper; a head fixing plate for supporting the thermal head; a frame for rotatably supporting the head fixing plate; and a spring for biasing the head fixing plate while being supported by the frame. And a thermal printer comprising a platen pressed against the thermal head and the recording paper by the biasing force of the spring ,
A rib formed integrally with the head fixing plate at a position substantially parallel to the longitudinal direction of the platen, and a support shaft supported by the frame, and arm portions at both ends are combined with the rib and at the center portion. A torsion coil spring having a shape of a double torsion spring in which an arm unites with the frame, and a support united with a central arm unit of the torsion coil spring, and bending the frame A thermal printer which is movable in the axial direction of the support shaft by releasing the system of the formed support portion and the torsion coil spring and the support portion .

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