JPH0634132Y2 - Thermal printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is a thermal printer, more specifically, an improvement of a thermal printer that prints on a heat-sensitive printing paper that passes over a platen roller while pressing a thermal head with the elastic force of a leaf spring. Regarding

(Prior Art and its Problems) Conventionally, Japanese Utility Model Laid-Open No. 55-42540 has been known as a structure for pressing a thermal head against printing paper using a leaf spring.

However, according to the above-described conventional structure, the leaf spring itself having a predetermined width is brought into contact with the head mounting plate of the thermal head. Therefore, when the leaf spring is mounted in a twisted state during processing or assembling process. In addition, since the grounding part of the leaf spring is offset from the center, the pressing force of the thermal head is not even on the left and right, and the print density on the left and right when printing on print paper may differ, especially when a bar code is printed. There was a problem that it could not be read by the scanner. It is therefore an object of the present invention to eliminate such a conventional problem and to provide a thermal printer that can even out the printing density evenly and improve the printing accuracy.

(Technical Means for Solving the Problems) In the thermal printer of the present invention, a support shaft is provided in parallel with the platen roller at a distance, and a head mounting plate having a thermal head is supported on the support shaft. The leaf spring is swingable in the circumferential direction and is swingably mounted in the vertical direction with respect to the widthwise center of the head mounting plate as a fulcrum, and biases the thermal head toward the platen roller. Is arranged approximately in the center in the width direction of the head mounting plate, and a pressing protrusion for reducing the contact area is formed at the tip of the plate spring to abut on the head mounting plate, and the rear end of the plate spring is mounted on the head. The leaf spring is rotatably mounted on the upper surface of the plate, and the leaf spring is installed in parallel with the head mounting plate. Further, the portion of the leaf spring between the tip pressing protrusion and the rear end mounting portion is projected in the head mounting plate direction. Adjustable size It is characterized in that it is pressed by a digit pressing member to generate an urging force on the leaf spring.

(Operation) According to the above-described configuration, since the head mounting plate can swing up and down with respect to the widthwise center of the plate, the thermal head can be used as a platen roller over substantially the entire widthwise direction. In this state, the tip of the leaf spring presses the center of the head mounting plate in the width direction so that the pressing force of the thermal head against the platen roller becomes even in the width direction. Can be secured evenly on the left and right.

Further, since the rear end of the leaf spring is rotatably mounted on the head mounting plate, no pressing force is generated by the tip end pressing protrusion when the pressing member does not press the plate spring, and the protruding amount of the pressing member is increased from this state. Is increased, the pressing force of the pressing protrusions is increased in proportion to this. Therefore, the pressing force of the tip pressing protrusion, that is, the adjustment range of the biasing force of the plate spring can be widened and finely adjusted, and the pressing force of the thermal head against the platen roller can be made more appropriate.

Further, since the head mounting plate is allowed to swing up and down in the width direction as described above, and the plate spring presses the substantially central portion of the head mounting plate in the width direction, the protrusion amount of the pressing member is changed. Even if the biasing force of the leaf spring is adjusted, the pressing force of the thermal head with respect to the platen roller is maintained without breaking left and right. Therefore, the work of adjusting the pressing force associated with the mounting and replacement of the thermal head is greatly simplified.

In addition, by installing the leaf spring in parallel with the head mounting plate, the height of the thermal head pressing mechanism is kept as small as possible, and the protruding stroke of the pressing member and A gap can be secured for the flexural deformation of the leaf spring.

In addition, since the tip of the leaf spring pushes the center of the head mounting plate in the width direction, even if the leaf spring is assembled in a twisted state, the pressing force of the thermal head is in the width direction. Since the head mounting plate is evenly provided on the left and right sides and the head mounting plate swings up and down with respect to the widthwise center of the platen as a fulcrum, the thermal head is brought into contact with the platen roller over the widthwise direction. Even if the roller or support shaft is mounted in a tilted state or the thermal head is warped, the tilting or warping can be absorbed and corrected. Therefore, the twist of the plate spring, the inclination of the platen roller, the support shaft, the warp of the thermal head, and the like do not pose a problem, so the processing accuracy and the assembly accuracy of the plate spring, the platen roller, the support shaft, and the thermal head are not required to be so high. Good workability and assembly.

(Embodiment) An embodiment of the present invention will be described with reference to the drawings.
In the figure, (1) is a platen roller, and (2) is a thermal head. The two (1) and (2) form a printing portion of a thermal printer, and heat-sensitive printing paper passing over the platen roller (1). The thermal head (2) is brought into contact with (a) in a pressed state to perform printing.

The platen roller (1) is cantilevered on a substrate (4) whose shaft (1 ') is erected on a base plate (3), and the substrate (4) is provided behind the platen roller (1). Support shafts (5) are installed in parallel at intervals, and left and right arm plates (6c) formed at the rear end of the head fixing plate (6) on the support shaft (5).
(6c) is rotatably mounted and the rear end of the head mounting plate (7) is rotatably mounted, and the thermal head (2) is mounted on the head mounting plate (7).

At the rear end of the head mounting plate (7), a support plate (8) is welded and integrally projected at approximately the center in the width direction, and a shaft hole (8 ') is bored in the support plate (8). Is rotatably attached to the support shaft (5) so that the head mounting plate (7) can be swung in the vertical direction, more specifically, in the direction orthogonal to the axial direction of the thermal head (2) or the platen roller (1). (Fig. 3, 1st
Figure).

Further, at the rear end of the head mounting plate (7), ear pieces (7a) (7a) formed by bending both left and right sides downward are integrally provided, and guides are provided on the ear pieces (7a) (7a). The holes (9) and (9) are opened and the support shaft (5) is inserted therethrough.

The guide hole (9) has a long hole shape extending in the vertical direction so that the head mounting plate (7) can swing around the support plate (8), but the head mounting plate (7) in the front and rear direction. The hole size in the front-rear direction that restricts the movement of the head (Fig. 4), and the ear pieces (7a) (7a) are attached to the arm plate (6c) of the head fixing plate (6).
(6c) The position where the head mounting plate (7) is located close to the inner surface restricts the axial movement of the support shaft (5) (Fig. 3).

As a result, movement of the head mounting plate (7) in the front-rear direction and the width direction is restricted, and the thermal head (2) is positioned at a predetermined position with respect to the platen roller (1).

The head mounting plate (7) is swingably mounted in the width direction of the head mounting plate (7) by using the support plate (8) as a fulcrum and the guide hole (9) extending in the vertical direction as a guide. The rocking of the platen roller (1)
The inclination of the support shaft (5) or the warp of the thermal head (2) is absorbed and corrected, and the thermal head (2) contacts the platen roller (1) over substantially the entire width direction.

The guide holes (9) and (9) of the ear pieces (7a) and (7a), the support shaft (5), and the arm plates (6c) and (6c) form guide means for positioning the head mounting plate (7).

The head mounting plate (7) has a front surface-shaped pin mounting plate (10) fixed to the upper surface of its substantially central portion by welding, and a pin (10a) extending in the left-right direction is horizontally mounted on the mounting plate (10). At the very least, the left and right both ear pieces (11a) (11a) of the leaf spring mounting plate (11) are rotatably attached to this pin (10a).

The leaf spring mounting plate (11) is horizontally disposed at a substantially central surface of the head mounting plate (7) with a space, and the rear end of the leaf spring (12) is placed on the mounting plate (11). Place the retainer plate (14) on the top and secure it by holding it with the flat head screws (13), and attach the leaf spring (12) to the front.

The leaf spring (12) has a hemispherical or substantially spherical pressing protrusion (15) having an outer diameter smaller than the width of the leaf spring, which is attached to the lower surface of the tip by press fitting, caulking or welding, and the pressing protrusion (15) is attached to the head. Position the front end of the mounting plate (7) approximately at the center.

The head fixing plate (6) has connecting portions (6b) (6b) on both left and right sides of a flat plate portion (6a) covering substantially the front half of the head mounting plate (7).
The arm plate (6c) extending vertically at each rear end via b)
The arm plate (6c), which is formed by integrally forming (6c).
As described above, the lower end of (6c) is rotatably attached to the support shaft (5) so that it can swing vertically about the support shaft (5).

The head fixing plate (6) has an adjusting screw (16) penetrating up and down attached to a substantially central portion of its flat plate portion (6a) so that the adjusting screw (16) can be screwed freely, and the lower end of the screw (16) corresponds to the upper surface of the leaf spring (12). The engaging pin (17) is attached to the arm plates (6c) (6c) so as to be in contact with each other, and the head fixing plate (6) is attached to the pin (17).
Install a coil spring (18) that urges in the upward swing direction (release side). On the other hand, an L-shaped lock lever (19) is swingably attached to the base plate (4) by a pin (20) and a lock groove (19a) provided in the lever (19) is engaged with the head fixing plate (6). By fitting the dowel pin (17), the head fixing plate (6) is fixed to the closing side position, that is, the position where the head mounting plate (7) is covered against the elasticity of the spring (18). At the rear end of the lock lever (19) is the lever (19).
A coil spring (21) for urging the lock lever toward the lock side is attached. When the lock lever (19) is swung in the opposite direction (direction of arrow A in Fig. 1) against the elasticity of the spring (21), Since the dowel pin (17) is disengaged from the lock groove (19a) of the lock lever (19), the head fixing plate (6) can swing toward the release side by the spring (18).

In addition, on the upper surface of the head mounting plate (7), the guide plates (22) (2) protruding above the flat plate portion (6a) of the head fixing plate (6) are provided.
When the head fixing plate (6) swings to the release side, the flat plate portion (6a) pushes up the guide plates (22) and (22). The head mounting plate (7) is released together with the head fixing plate (6), and the thermal head (2) is separated from the platen roller (1) so that its inspection and replacement can be performed. Further, in the figure, (23) is a cutter attached to the front surface of the head fixing plate (6), (24) is a guide roller attached to the front surface of the head fixing plate (6) via an attachment plate (25), (26 ) Is a dispenser attached to the substrate, (27) is a window hole opened in the substrate (4) for allowing the engagement pin (17) to swing, and (28) is a screw for attaching the spindle (5) , (29) is a retaining ring. When the head fixing plate (6) is locked to the closing side as shown in FIG. 1, the lower end of the adjusting screw (16) is the leaf spring (15).
The leaf spring (12) is pushed downward by grounding on the upper surface, and the elastic force of the leaf spring (12) acts on the head mounting plate (7) in the substantially axial center thereof via the pressing protrusion (15) to cause the thermal head. The thermal head (2) is pressed and brought into contact with the printing paper (a) on the platen roller (1) by urging (2) downward.

The pressing force of the thermal head (2) can be adjusted by screwing the adjusting screw (16) to change the downward protruding length thereof.

The contact area of the pressing protrusion (15) with the head mounting plate (7) is smaller than that in the case where the flat plate spring is directly grounded. Regardless of the width of the spring (12), even when the leaf spring is attached by being twisted, the deviation from the center is extremely small and the left and right pressing forces can be made substantially equal.

Incidentally, in the above-mentioned embodiment, regarding the guide means for positioning the head mounting plate (7), the ear piece (7
Although a long hole-shaped guide hole (9) is shown in (a) and (7a), it is not limited to the ear piece structure having the long hole, and the guide hole (9) can be placed above and below the spindle. The movable guide piece may be pressed against the support shaft in the same direction.

Next, FIGS. 5 to 11 show modified examples of the pressing protrusion.

The pressing protrusion (15a) of FIG. 5 is formed into a hemispherical shape by drawing on the tip of the leaf spring (12a), and the pressing protrusion (15b) of FIG. 6 is drawn on the tip of the leaf spring (12b) by drawing. It is a structure formed in a short column shape.

The pressing protrusion (15c) in FIG. 7 is a member different from the leaf spring (12c) and formed in an inverted conical shape, and is attached to the tip of the leaf spring (12c). The pressing protrusions (15
In the structure d), the tip of the leaf spring (12d) is bent downward at a right angle, the bent part is formed into an inverted triangle, and the lower end is formed into an arc.

The pressing protrusion (15e) shown in FIGS. 10 and 11 extends in the direction orthogonal to the axial direction of the platen roller (1) by drawing the tip of the leaf spring (12e), that is, in the longitudinal direction of the leaf spring (12e). The structure is made to project in an elongated shape, and its width is smaller than the width of the leaf spring (12e).

When the pressing protrusion is formed as a member different from the leaf spring, the material thereof is metal, resin material, hard rubber material or the like, and the attachment method is press fitting, caulking, welding, adhesion or the like.

Next, an optimum embodiment of a thermal type label printer using the present invention will be described with reference to FIG. 12. In the figure, (100) is a case, (101) is a label position detector, (102) is a guide roller, ( 103) a printing section including the main part of the present invention, (104)
Is a label issuing port, (105) is a motor for driving and rotating the platen roller (1), (106) is a label roll paper (107)
A roll paper support device for supporting the
(109) A motor for driving the winding shaft.

The label roll paper (107) has a label (a), which is a heat-sensitive printing paper, adhered on the mount paper at regular intervals, and is pulled out from the supporting device (106) by the rotation of the platen roller (1). (1) Required data is printed by the thermal head (2) when passing over, the label (a) is peeled from the mount (b) through the dispenser (26) and is issued from the label issuing port (104), The mount (b) is wound around the winding shaft (108) through the guide roll (102).

(Effect) Since the thermal printer according to the first to third aspects of the present invention is configured as described above, the following effects can be obtained.

The head mounting plate swings up and down in the width direction to bring the thermal head into contact with the platen roller over substantially the entire width direction, and in this state, the tip pressing protrusion of the leaf spring causes the head mounting plate to move in the width direction substantially. By pressing the center, the pressing force of the thermal head with respect to the platen roller is made uniform in the left-right direction in the width direction, and the printing density by the thermal head can be ensured evenly in the left-right direction. Therefore, the uniformity of the print density is ensured to improve the printing accuracy, and even when the bar code is printed, the print density on the left and right is made uniform and the reading rate by the scanner is improved.

By rotatably mounting the leaf spring rear end on the head mounting plate and installing the leaf spring parallel to the head mounting plate, the range of adjustment of the leaf spring biasing force by the pressing member can be widened and fine adjustment can be performed. By making the pressing force of the thermal head against the platen roller, that is, the pressing force of the thermal head against the heat-sensitive printing paper appropriate, it is possible to further improve the printing accuracy.

As described above, since the head mounting plate is allowed to swing up and down in the width direction and the plate spring presses the substantially central portion of the head mounting plate in the width direction, the protruding amount of the pressing member is changed. Even if the spring biasing force is adjusted, the pressing force of the thermal head with respect to the platen roller is maintained without breaking left and right evenness. Therefore, mounting the thermal head,
The adjustment of the pressing force associated with replacement or the like is simplified, and workability during assembly and maintenance can be significantly improved.

By installing the leaf spring in parallel with the head mounting plate, the height of the thermal head pressing mechanism can be made as small as possible, and the protrusion stroke of the pressing member and the leaf spring by the protruding height of the tip pressing protrusion. Since a gap for flexural deformation of the printer can be secured, while facilitating the simplification of the inside of the printer due to the thinning around the printing portion and the miniaturization of the printer,
The effects (1) to (3) above can be achieved.

Since the twist of the leaf spring, the platen roller, the inclination of the support shaft, the warp of the thermal head, etc. are not a problem, the leaf spring,
Since the platen roller, spindle, and thermal head are not required to have high processing accuracy and assembly accuracy, it is possible to reduce the defective rate in processing and shorten the assembly time.
Manufacturability can be greatly improved.

According to the second aspect, the positioning of the thermal head with respect to the platen roller is accurately performed, and the point of action of the pressing protrusion on the head mounting plate is accurately positioned to further ensure the above-mentioned effect. According to the item (3), it is possible to secure the desired effect by minimizing the necessary amount.

[Brief description of drawings]

FIG. 1 is a sectional side view of the present invention, which is shown in FIG.
-(I) line sectional view, FIG. 2 is a (II)-(II) line sectional plan view of FIG. 1, FIG. 3 is a (III)-(III) line sectional view of FIG. 2, and FIG. Is a sectional view taken along line (IV)-(IV) of FIG. 3, FIGS. 5 and 6 are sectional views showing modified examples of the pressing protrusions, and FIGS. 7 and 8 are further modified examples of the pressing protrusions. Side view, 9th
8 is a front view of FIG. 8, FIG. 10 is a plan view showing a further modification of the pressing protrusion, FIG. 11 is its plan view, and FIG. 12 is a sectional side view of a label printer using the present invention. In the figure (1) …… Platen roller (2) …… Thermal head (5) …… Spindle (6) …… Head fixing plate (7) …… Head mounting plate (6c) …… Arm plate (8)… Support plate (9) Guide holes (12) (12a) (12b) (12c) (12d) (12e) …… Leaf springs (15) (15a) (15b) (15c) (15d) (15e) …… Pressing protrusion (10a) …… Pin (11) …… Leaf spring mounting plate (16) …… Adjustment screw

Claims (3)

[Scope of utility model registration request] 1. A thermal printer which prints on a heat-sensitive printing paper passing over a platen roller while pressing a thermal head by the elastic force of a leaf spring, wherein a spindle is provided in parallel with the platen roller and the spindle is provided. In addition, the head mounting plate with the thermal head mounted thereon is swingable with respect to the circumferential direction of the support shaft, and is mounted so as to be swingable vertically with respect to the widthwise center of the head mounting plate as a fulcrum.
The leaf spring for urging the thermal head toward the platen roller is arranged substantially in the center of the head mounting plate in the width direction, and a pressing protrusion for reducing the contact area is formed at the tip of the leaf spring to contact the head mounting plate. The leaf spring is attached to the head mounting plate so that the leaf spring is rotatably attached to the upper surface of the head mounting plate, and the leaf spring is installed parallel to the head mounting plate. A thermal printer characterized in that a portion between the two is pressed by a pressing member that is provided so as to adjust the protrusion size in the head mounting plate direction to generate an urging force on the plate spring. 2. The head mounting plate has guide means which is swingably mounted on the support shaft through a support plate provided substantially in the center in the width direction and which is positioned at a predetermined position with respect to the platen roller. The thermal printer according to item 1. 3. The thermal printer according to claim 1, wherein the pressing projection has a shape in which a contact area is reduced at least in the axial direction of the platen roller.