JPH11301051A - Thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform stable printing without being affected by part accuracy or assembling accuracy. SOLUTION: A thermal head 5 is arranged in opposed relation to a platen 3 to be provided to the front end part of a holding plate 7 and guide members 8 are respectively provided to the holding plate 7 on both sides of the central part 7a thereof. The guide shaft 10 fixed to a housing is fitted in the guide groove 8a of the guide member 8 determines the before and behind positions of the thermal head 5 to the platen 3. The support shaft 12 supporting the holding plate 7 laterally in a freely shakable manner is provided to the rear end part 7b of the holding plate 7. The thermal head 5 can be closely brought into contact with the platen 3 by the shaking of the holding plate 7 to enhance printing quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer for printing on printing paper, and more particularly to a thermal printer capable of improving printing quality.

[0002]

2. Description of the Related Art In a thermal printer for performing thermal printing on printing paper using a thermal head, the printing quality varies due to, for example, the inclination of the thermal head with respect to a platen.
That is, if the heating elements arranged in a straight line on the thermal head have different contact states with respect to the peripheral surface of the cylindrical platen, uneven printing density occurs.

For this reason, the conventional thermal head is configured such that the contact state of the thermal head with the platen can be changed. FIG. 5 is a plan view showing a conventional thermal printer, and FIG. 6 is a side view of the same. A platen 51 that is rotationally driven is pivotally supported by the housing 50. The platen 51 is provided with a thermal head 52 opposed thereto. The platen 51 is arranged so that the axial direction thereof coincides with the axial direction of the thermal head 52 (the arrangement direction of the heating elements).
Then, the printing paper R is transported and driven in the illustrated direction A, and printing is performed by the thermal head 52.

The thermal head 52 is fixed to one end 53a of a holding plate 53. Base end 53b of holding plate 53
Is fixed to a flat connector 53c that faces in a direction perpendicular to the axial direction of the thermal head 52. The connecting tool 53c is supported by a support plate 55 fixed to the apparatus via a shaft member 56. As a result, the holding plate 53 is rotatable in the direction B in the drawing, and the thermal head 52 can be opened and closed with respect to the platen 51. Further, the contact pressure of the thermal head 52 with the platen 51 can be varied by adjusting a spring (not shown).

[0005]

However, in the conventional thermal printer, the contact pressure of the thermal head 52 on the platen 51 cannot be made uniform, and the printing quality cannot be improved. These fluctuate based on variations in processing accuracy of parts, assembly errors, and the like.

For example, if the surface position of the mounting surface between the support plate 55 and the connecting member 53c is at an angle with respect to the transport direction A of the printing paper R, the thermal head 52
Will be shifted in the axial direction. Also, this connecting tool 53c
Is inclined (a state not perpendicular to the transport direction A of the printing paper R), the thermal head 5
2 cannot contact uniformly.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a thermal printer capable of performing stable printing without being affected by parts and assembly accuracy.

[0008]

According to a first aspect of the present invention, there is provided a thermal printer for performing a predetermined printing on a printing paper (R). A thermal head (5) having a predetermined length and having a plurality of heating elements (5a) for performing thermal printing on the printing paper; and a direction (A) disposed opposite to the thermal head and orthogonal to the arrangement direction of the heating elements. A platen (3) of a predetermined length for transporting the printing paper, and an axis in the arrangement direction of the heating elements of the thermal head with respect to a center position in the length direction of the thermal head as a center, with respect to the axis of the platen. And a biasing means (15) for biasing the thermal head in the direction of the platen.

The thermal head (5) is fixed to a holding plate (7) having a surface along a conveying surface of the printing paper (R), and the oscillating means is provided. ,
A guide member (8) provided on both sides of the holding plate and having guide grooves (8a) oriented in a direction perpendicular to the transport direction; and fixedly arranged at opposing positions of the guide member to guide the guide member. A guide shaft (10) that is inserted into the groove, positions the holding plate at a predetermined position in the transport direction of the printing paper, and enables the holding plate to swing;
The thermal head is provided at a central position in the length direction of the thermal head on the holding plate on an axis orthogonal to the length direction, and has an axis along the axis. A supporting shaft (12) for swinging in the direction,
The holding plate may be held at a total of three points of the two guide shafts and the one support shaft.

[0010] According to a third aspect of the present invention, the axis of the support shaft (12) may be provided at a position passing through a surface position of a heating element (5a) of the thermal head (5). .

According to the above configuration, the holding plate 7 is provided with the support shaft 1.
2, the platen 3 and the thermal head 5 can be aligned in the axial direction. Thereby, the thermal head 5 can be uniformly and closely contacted with the platen 3, and the printing quality can be improved.

[0012]

FIG. 1 is a side view showing a thermal printer according to the present invention, and FIG. 2 is a plan view thereof. A platen 3 is rotatably supported in a housing 2 of the thermal printer 1. The platen 3 is rotated by a drive mechanism (not shown) and transports the printing paper R in the direction A in the figure. Printing paper R
Has a superposed structure in which a plurality of rectangular printing paper bodies having a predetermined length are adhered on a long mounting paper.

A thermal head 5 is arranged at a position facing the platen 3. The printing paper R is printed by the thermal head 5.
The predetermined printing is performed on the printing paper body. The axial direction of the thermal head 5 (the arrangement direction of the heating elements 5a) and the axial direction of the platen 3 (the depth direction in the figure) are provided so as to match each other. The surface of the thermal head 5 (portion of the heating element 5a) is fixed to a platen 3 by a guide member 8 described later.
Are positioned so as to be orthogonal to the perpendicular line of the outer peripheral surface of (the tangential line).

The holding plate 7 is provided in parallel with the surface of the thermal head 5 (the surface of the heating element), and fixedly holds the thermal head 5 at the front end 7a. At the center of the rear end 7b of the holding plate 7, a downwardly bent piece 7d is formed to be bent at a right angle.

Guide members 8 are formed at right angles on both sides of the central portion 7c of the holding plate 7, respectively. The guide member 8 is formed with a guide groove 8a having a lower opening. The groove direction of the guide groove 8a has an angle perpendicular to the surface of the holding plate 7. A guide shaft 10 fixed to the housing 2 is fitted into the guide groove 8a to position the holding plate 7. The guide member 8 is positioned so that the axial direction of the platen 3 matches the axial direction of the thermal head 5.

A support shaft 12 is erected and fixed to a bent piece 7d provided at a rear end 7b of the holding plate 7. The support shaft 12 includes a screw 12a screwed and fixed to the bending piece 7d,
It is composed of a cylindrical collar 12b fitted into the screw 12a. The support shaft 12 is supported by a shaft hole 14 a opened in a fixture 14 fixed to the housing 2. FIG.
As shown in the front view, the axial position of the support shaft 12 is set at a height position substantially coincident with the surface position of the thermal head 5 (the surface of the heating element 5a).

Thus, the holding plate 7 can swing left and right (in the direction C in FIG. 3) about the axis of the support shaft 12. That is, the axial position of the thermal head 5 (with the arrangement direction of the heating elements 5 a as an axis) can be inclined with respect to the axial position of the platen 3. In other words, the distance between the axial ends of the platen 3 and the surface position of the thermal head 5 can be changed. The guide groove 8a is formed along the swing direction and does not hinder the swing.

At the front end 7a of the holding plate 7, biasing springs 15 are provided on both sides. One end 1 of the biasing spring 15
5a is held by the housing 2 and the other end 15b is held by the holding plate 7
Is pressed at the front end 7a. The biasing spring 15 causes the thermal head 5 to contact the platen 3 at a predetermined contact pressure.
The biasing spring 15 is not limited to a coil spring as shown in the figure, but is an example of a biasing unit made of another plate spring or an elastic body such as rubber.

According to the above configuration, the holding plate 7 has a total of three support structures in which two points on both sides are guided and supported by the guide member 8 and one point on the rear end is supported by the support shaft 12. ing.
A swing means is constituted by the guide member 8 and the support shaft 12, and the holding plate 7 is swingable right and left around the axial direction of the support shaft 12. Accordingly, the axial position of the thermal head 5 can be inclined with respect to the axial position of the platen 3, and the entire surface of the thermal head 5 can be brought into contact with the outer peripheral surface of the platen 3.

For example, as shown in the operation diagram of FIG. 4, even when the axis of the platen 3 is inclined and the axial direction of the platen 3 and the The head 5 swings to be able to coincide with the axial direction of the platen 3. This allows
Even if there is a processing error of the parts, an assembly error, etc., these error components can be absorbed, and the linear heating elements 5a provided on the thermal head 5 are all arranged on the platen 3 with a uniform contact pressure.
Will be able to contact In addition, the thermal head 5
It is urged in the direction of the platen 3 by the urging spring 15,
The thermal head 5 is always in close contact with the platen 3.

In the above description, the state before and after the printing paper issuance operation has been described, but the same applies during the printing paper issuance.
During printing, the thermal head 5 can come into close contact with the platen 3 with the printing paper R interposed therebetween, and the printing quality can be improved.

In the above embodiment, the structure in which the support shaft 12 is fixed to the holding plate 7 has been described.
2 may be fixed to the fixture 14 side, and a shaft hole may be opened and supported on the holding plate 7 side. Further, the guide groove 8a is provided on the holding plate 7 side, and the guide shaft 10 is provided on the housing 2 side. However, the guide groove 8a is provided on the housing 2 side, and the guide shaft 10 is provided on the holding plate 7 side. It may be configured. In any case, the same operation and effect as described above can be obtained.

[0023]

According to the present invention, since the thermal head has a structure capable of swinging in the arrangement direction of the heating elements, the entire thermal head can always contact the platen with a uniform pressure. As a result, an effect is obtained in which stable printing can be performed without being affected by parts or assembly accuracy.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of a thermal printer of the present invention.

FIG. 2 is a plan view of the thermal printer.

FIG. 3 is a front view of the thermal printer.

FIG. 4 is an operation diagram of the thermal printer.

FIG. 5 is a plan view showing a conventional thermal printer.

FIG. 6 is a side view of the conventional thermal printer.

[Explanation of symbols]

1: thermal printer, 2: housing, 3: platen, 5:
Thermal head, 5a: surface provided with a heating element, 7: holding plate, 8: guide member, 10: guide shaft, 12: support shaft,
R: printing paper.

Claims (3)

[Claims] 1. A thermal printer for performing a predetermined printing on a printing paper (R), comprising a plurality of heating elements (5a) arranged linearly, and a thermal head (5) having a predetermined length for performing thermal printing on the printing paper. ), A platen (3) of a predetermined length which is arranged to face the thermal head and conveys the printing paper in a direction (A) orthogonal to the arrangement direction of the heating elements, and a central position in the length direction of the thermal head Swinging means for swinging the axis of the thermal head in the arrangement direction of the thermal head with respect to the axial direction of the platen; and biasing means (15) for biasing the thermal head in the platen direction. A thermal printer comprising: 2. The thermal head (5) is fixed to a holding plate (7) having a surface along a conveying surface of the printing paper (R), and the swing means is provided on both sides of the holding plate. Guide members (8) each having a guide groove (8a) oriented in a direction orthogonal to the transport direction; and fixedly arranged at positions opposing the guide member, and inserted through the guide grooves of the guide member, A guide shaft (10) for positioning the holding plate at a predetermined position in the conveyance direction of the printing paper and for allowing the holding plate to swing, and a center position in the length direction of the thermal head and orthogonal to the length direction. A support shaft (12) that is pivotally supported by the holding plate on the axis of the platen and has an axis along the axis, and swings the holding plate in the axial direction of the platen. The total of the two guide shafts and the one support shaft Thermal printer according to claim 1, wherein which is configured to hold the holding plate at a point. 3. The thermal printer according to claim 2, wherein an axis of said support shaft is provided at a position passing through a surface position of a heating element of said thermal head.