JPH11301052A - 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 provided at the front end part 7a of a holding plate 7 at the position opposed to a platen 3 and a freely up-and-down movable adjusting plate 14 is connected to the rear end part 7b of the holding plate 7. The guide member 8 positioning the holding plate 7 is provided to the central part 7c of the holding plate 7. When the adjusting plate 14 is moved up and down by operating an adjusting jig, the rear end part 7b of the holding plate 7 is revolved to vary the contract angle of the thermal head 5 with the platen 3 and the thermal head 5 is finely moved in the before-and-behind direction of the platen 3.

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 depending on the position 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. 8 is a plan view showing a conventional thermal printer, and FIG. 9 is a side view thereof. 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 mounting position of the connecting member 53c shifts back and forth in the transport direction of the printing paper R, the contact position of the thermal head 52 with the platen 51 shifts back and forth, so that good printing cannot be performed. In addition, the support plate 55 and the connecting member 5
Due to the fitting accuracy of 3c, the thermal head 52 comes into contact with the platen 51 in an inclined state.

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]

In order to achieve the above object, a thermal printer according to the present invention is a thermal printer for performing predetermined printing on a printing paper (R), wherein a plurality of heating elements (5a A) a thermal head (5) having a predetermined length for thermally printing the printing paper, and a predetermined head which is disposed opposite to the thermal head and conveys the printing paper in a direction (A) orthogonal to the arrangement direction of the heating elements. A long platen (3) and a holding plate (7) for supporting the thermal head
Biasing means (15) for biasing the surface of the thermal head on which the heating element is provided in the direction of the platen; and holding the holding plate around the rotation axis of the holding plate. And moving means for rotating the contact point of the thermal head with the platen back and forth in the transport direction of the printing paper by rotating in a perpendicular direction.

Further, as described in claim 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 rotates integrally. The moving means is provided on both sides of the holding plate, and guides the holding plate in the rotation direction while positioning the holding plate at a predetermined position in the front-back direction of the printing paper transport direction. A guide member (8) having a groove (8a), a guide shaft (10) fixedly disposed at a position facing the guide member and inserted through a guide groove of the guide member, An adjusting plate (14), which is movable in the vertical direction, is connected to the rear part of the holding plate and rotates the holding plate, and an adjusting tool (12) for moving the adjusting plate in the vertical direction. be able to.

[0010] Further, the thermal head (5) may be provided with a swinging means for swinging the thermal head (5) in the axial direction of the platen (3).

According to the above configuration, by operating the adjusting tool 12, the adjusting plate 14 moves up and down. As a result, the rear end 7b of the holding plate 7 rotates, and the contact angle of the thermal head 5 with respect to the platen 3 is changed. Due to this angle change, the thermal head 5 slightly moves in the front-back direction of the platen 3. As a result, the heating element 5a of the thermal head 5 can be brought into close contact with the platen 3, and the printing quality can be improved.

[0012]

FIG. 1 is a side view showing a thermal printer of the present invention, FIG. 2 is a side view showing a main part of the thermal printer, FIG. 3 is a plan view of FIG. 2, and FIG. It is a front view. 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. The 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 (the heating element 5a portion) is positioned so as to be perpendicular to the outer peripheral surface of the platen 3 (positioned on a tangent 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 provided with the shaft hole 1 of the adjustment plate 14.
4d, it is supported so as to be movable in the front-rear direction of the transport direction of the printing paper R.

The adjusting plate 14 is formed of a plate extending vertically of the apparatus. The upper end of the adjusting plate 14 has a bent portion 14a parallel to the upper surface 2a of the housing 2. A bent portion 14c having a predetermined angle is provided substantially at the center. The lower end has the support shaft 12
Is formed. The shaft hole 14d is opened slightly larger than the shaft diameter of the support shaft 12, and
The end surface has a tapered inclined surface 14da. Thus, the axial direction of the support shaft 12 can be inclined at a predetermined angle in all directions in the shaft hole 14d.

A predetermined gap is provided between the upper surface 2a of the housing 2 and the bent portion 14a, and an adjusting tool 17 is provided between them. The adjusting tool 17 is constituted by a screw 17a shown in the figure, the head is exposed on the upper surface 2a, and the screw groove is screwed into the screw hole 14e of the bent portion 14a. A coil spring 17f is interposed in the screw 17a, and constantly urges the adjusting tool 17 downward, and prevents the screw 17a from loosening to maintain the adjusted vertical position of the adjusting tool 17 in a fixed state. I do.
By adjusting the screw 17a, the adjustment plate 14 can be moved up and down (in the direction D in the drawing). Note that the adjustment plate 14 has a configuration in which a side portion is guided by a guide member (not shown), and moves only in the vertical direction.

As shown in the front views of FIGS. 2 and 4, the axial position of the support shaft 12, the axial position of the guide shaft 10, and the surface position of the thermal head 5 (the surface of the heating element 5a) substantially coincide with each other. It is set to be located on a straight line. Thus, the holding plate 7 can swing left and right (in the direction C in FIG. 4) 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 5a as an axis) is
Can be tilted with respect to the axial position. 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.

The operation of the above configuration will be described. (1) Left and right swing As described above, the holding plate 7 is supported at two points on both sides by the guide member 8 and supported at one point at the rear end by the support shaft 12 for a total of three points. It has a configuration. 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. 5, when the axis of the platen 3 is inclined and the axial direction of 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.

(2) Forward / backward movement of the thermal head 5 By moving the adjusting plate 14 up and down, the thermal head 5 in contact with the platen 3 can be moved (finely adjusted) back and forth in the transport direction of the printing paper R. This forward / backward movement is achieved by moving means having the respective configurations of the guide member 8, the guide shaft 10, the support shaft 12, the adjustment plate 14, and the adjustment tool 17.
When the screw 12a of the adjusting tool 12 is rotated in one direction, FIG.
As shown in the operation diagram, the adjustment plate 14 moves upward (in the direction D1 in the figure). Correspondingly, the support shaft 12 is pulled up. On the other hand, the front of the holding plate 7 is urged by an urging spring 15. As a result, the rear end 7b of the holding plate 7 rotates upward (in the direction of E1 in the figure) around the point where the platen 3 and the thermal head 5 are in contact. In FIG. 6, a solid line indicates a position before the movement of each part, and a two-dot chain line indicates a position after the movement.

As a result, the contact angle of the thermal head 5 with the platen 3 has a predetermined angle between the angle (X0) before the movement and the angle (X1) after the movement. Since the outer periphery of the platen 3 has an arc shape having a predetermined diameter, the contact position of the thermal head 5 with respect to the peripheral surface of the platen 3 moves forward (slightly moves) based on the angle difference. As a result, the position of the heating element 5 a is relatively rearward with respect to the platen 3.

FIG. 7 shows an operation diagram when the screw 12a is rotated in the other direction. As a result, the adjustment plate 14 descends (in the direction D2 in the figure). Correspondingly, the support shaft 12 is pushed down, and the holding plate 7 pivots downward (in the direction of E2 in the figure) on the rear end portion 7b side. The contact angle of the thermal head 5 with the platen 3 is equal to the angle (X
0) and the angle (X2) after the movement, a predetermined angle is generated, and after the movement, the contact position of the thermal head 5 with respect to the peripheral surface of the platen 3 moves backward (fine movement). As a result, the position of the heating element 5 a is relatively forward with respect to the platen 3.

The amount of movement of the thermal head 5 in the front-rear direction can be continuously varied according to the amount of rotation of the screw 12a. Then, the adjustment plate 14 is moved up and down relatively large to rotate the rear end 7b of the holding plate 7 up and down to finely move the contact point between the thermal head 5 and the platen 3 on the front end 7a side. The movement of the thermal head 5 in the front-rear direction can be finely and finely adjusted by rotating the screw 12.

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 adjustment plate 14 side, and an axial 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 8 is provided on the holding plate 7 side. 10 may be provided. Further, the guide member 8 and the guide shaft 10 are provided on both sides of the holding plate 7, respectively. However, the present invention is not limited to this. For example, a single block-shaped guide member 8 having a predetermined length (a predetermined length in a direction orthogonal to the conveying direction of the guide shaft print paper R) is provided at the center of the holding plate 7. And
The guide member 8 forms a guide groove 8 a upwardly with respect to the surface of the holding plate 7. A guide shaft 10 fixed to the housing 2 is inserted into the guide groove 8a. Also in this configuration, the holding plate 7 rotates up and down, and the thermal head 5 can be moved in the front-back direction. In each of the above-described modifications, the same operation and effect as described above can be obtained.

[0030]

According to the present invention, the thermal head can be finely adjusted in the front-rear direction of the printing paper conveyance direction, so that the position of the heating element of the thermal head with respect to the platen can be adjusted to an optimum position. Become. As a result, an effect is obtained in which stable printing can be performed without being affected by component tolerances 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 side view showing a main part of the thermal printer.

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

FIG. 4 is a front view of the thermal printer.

FIG. 5 is an operation diagram of the thermal printer.

FIG. 6 is an operation diagram showing forward movement of the thermal head.

FIG. 7 is an operation diagram showing backward movement of the thermal head.

FIG. 8 is a plan view showing a conventional thermal printer.

FIG. 9 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,
14 ... Adjustment plate, R ... Print 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 thermally printing the printing paper. ), A platen (3) arranged opposite to the thermal head and transporting the printing paper in a direction (A) orthogonal to the arrangement direction of the heating elements, and a holding plate (7) supporting the thermal head. ), An urging means (15) for urging the surface of the thermal head on which the heating element is provided in the direction of the platen, and a conveying surface of the printing paper on the holding plate about a rotation axis of the holding plate. And a moving means for rotating the contact point of the thermal head with the platen back and forth in the transport direction of the printing paper by rotating in a direction perpendicular to the printing paper. 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 rotates integrally therewith. Guide grooves (8) provided on both sides of the plate to guide the holding plate in the rotation direction while positioning the holding plate at a predetermined position in the front-rear direction of the printing paper transport direction.
(a), a guide shaft (10) fixedly disposed at a position facing the guide member and inserted through a guide groove of the guide member, and a vertical direction with respect to a conveying direction of the printing paper. An adjusting plate (14), which is movable to the rear of the holding plate and rotates the holding plate, and an adjusting tool (12) for moving the adjusting plate in the vertical direction.
2. The thermal printer according to claim 1, comprising: 3. The thermal printer according to claim 1, further comprising swing means for swinging the thermal head (5) in an axial direction of the platen (3).