JPH08156366A - Thermal head supporting device - Google Patents

Abstract

PURPOSE: To provide a thermal head supporting device in which the heating line of the head can be easily regulated in parallel with the axial center of a platen per a head unit. CONSTITUTION: The thermal head supporting device comprises a head support 4 detachably coupled to a head pressing and releasing mechanism 17 at a predetermined play in the direction for varying the parallelism to the platen 2, a thermal head 1 so assembled with a mount 5 formed at the support 4 as to be displaced, locking pieces 10 each having a cutout 7 detachably engaged with a concentric circle 3 disposed coaxially near both ends of the platen 2 and formed integrally with both sides of the support 4, and a head unit 16 formed of a fine regulating member 13 for finely regulating the position of the head 1 to the support 4. The cutout 7 of the piece 10 formed integrally with the support 4 is engaged in a concentric part 3 while displaying the support 4 to the mechanism 17 in the range of the play.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head supporting device used in a thermal printer.

[0002]

2. Description of the Related Art In a thermal printer, when printing, when a thermal head is pressed against a sheet or an ink ribbon on a platen to insert the sheet or the ink ribbon between the platen and the thermal head, or when the sheet is conveyed. It is necessary to separate the thermal head from the platen. Therefore, various structures have been proposed in which the thermal head is supported so as to be freely separated from and attached to the platen.

For example, in Japanese Unexamined Patent Publication No. 2-139268, a frame supporting a thermal head is urged in a direction away from the platen, a cam presses the frame toward the platen, and the frame is thermally moved depending on a rotational position of the cam. The content of separating from the platen together with the head is described.

Further, in JP-A-2-281984, a head support plate to which a thermal head is fixed is swingably supported by a support shaft, and both sides of the head support plate are biased by independent springs. The thermal head is brought into pressure contact with the platen by rotating the head so that both ends of the spindle are finely moved together with the head support by the long grooves formed in the opposite side plates. It is described that the platen is pressed against the platen with a uniform pressure.

Further, in Japanese Patent Publication No. 55-39465 (Japanese Patent Laid-Open No. 52-119337), a thermal head is fixed to a block via a connecting member, and an assembly of the thermal head, the connecting member and the block is attached to a gimbal joint. The thermal head is pressed against the platen by a spring and the thermal head is brought into pressure contact with the platen, and the rod provided on the block is pulled to pull the thermal head away from the platen.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the invention described in Japanese Patent Publication No. 8, the frame for holding the thermal head is penetrated by the shaft serving as the fulcrum of rotation, so that it is difficult to attach and detach the frame together with the thermal head during assembly or maintenance. Also,
Although a large number of heat generating elements are arranged in the thermal head along the axial direction of the platen, it is impossible or extremely difficult to adjust the heat generating lines by these heat generating elements to be parallel to the platen.

Also in the invention described in JP-A-2-281984, it is difficult to attach / detach the thermal head together with the head support plate because the support shaft penetrates the side plate and the head support plate. Further, although the pressure contact force of the thermal head with respect to the platen can be made uniform, it is expected that it is very difficult to adjust the heat generation line of the thermal head in parallel with the platen.

In the invention disclosed in Japanese Patent Publication No. 55-39465, since the connecting member is held by the gimbal joint, it is expected that this connecting member will be replaced with the thermal head. However, this gimbal joint cannot adjust the heating line of the thermal head parallel to the platen in the paper transport direction.

Further, in the thermal head assembly described in each of the above publications, the heat generating line of the thermal head cannot be adjusted in parallel with the platen in the unit of the assembly when separated from the printer.

[0010]

SUMMARY OF THE INVENTION The present invention is detachably connected to a head pressing / releasing mechanism that is displaceably contactable and separable with respect to a platen in a direction in which parallelism with the platen changes with a predetermined play. A head support, a thermal head displaceably assembled to a mounting portion formed on the head support to face the platen, and a concentric circle portion coaxially arranged near both ends of the platen to be detachably fitted. A pair of left and right locking pieces that are integrally formed on both sides of the head support body with cutouts to be fitted, and a heating line formed by a number of heating elements arranged in the thermal head connects the centers of the cutouts. A thermal head supporting device in which a head unit is formed by a fine adjustment member for finely adjusting the position of the thermal head with respect to the head support in a direction parallel to That.

[0011]

According to the present invention, since the locking pieces having the notches are integrally formed on both sides of the head support for supporting the thermal head, the positional relationship between the head support and the notch with respect to the head support is accurate. Stipulated in. On the other hand, even when the head support is connected to the head pressing / releasing mechanism, the head support is allowed to move in the direction in which the parallelism with the platen changes, so the left and right cutouts are fitted to the concentric circles of the platen. Thereby, the parallelism between the platen and the heat generation line of the thermal head can be easily determined. Moreover, even if the variation in the size of the head support exceeds the allowable range, the parallelism between the heating line of the thermal head and the straight line connecting the cutout is corrected in units of the head unit by operating the fine adjustment member. .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the thermal head 1
A heating line 1a is formed by arranging a large number of heating elements along the axial direction of the platen 2. At both ends of the platen 2, bearings 3 that are concentric circles located on the axis thereof are provided.

Next, there is provided a head support 4 for movably supporting the thermal head 1 in the direction in which the parallelism with the platen 2 changes. That is, oval mounting holes 5 that are long in the vertical direction are formed as mounting portions on both sides of the head support 4, and mounting screws 6 that pass through these mounting holes 5 are formed on the back surface of the thermal head 1 ( The thermal head 1 is coupled to the head support body 4 by screwing (not shown). Further, on both sides of the head support 4, locking pieces 10 having notches 7 fitted into the bearings 3 and bearing fitting holes 9 for rotatably holding both ends of the ribbon guide roller 8 are integrally formed. Has been formed.

In addition, bent pieces 11 bent inward are formed at upper portions on both sides of the head support 4. The bent pieces 11 are brought into contact with the upward contact surface 12 of the thermal head 1 to support the heating line 1a of the thermal head 1 in a direction parallel to the straight line connecting the centers of the notches 7. Thermal head 1 for body 4
An adjusting screw 13 is screwed as a fine adjusting member for finely adjusting the position of.

The projecting length of the adjusting screw 13 projecting from the lower surface of the bending piece 11 is fixed in design.
Therefore, during assembly, the protruding length of the adjusting screw 13 from the lower surface of the bending piece 11 is made constant, and in this state, the adjusting screw 1
The contact surface 12 of the thermal head 1 is brought into contact with the lower end of the thermal head 3, and while maintaining this state, the mounting screw 6 passed through the mounting hole 5 is screwed into the rear surface of the thermal head 1 to connect the center of the notch 7. The straight line and the heat generation line 1a of the thermal head 1 are parallel to each other. The bearing 1 fitted in the bearing fitting hole 9
4, the both ends of the ribbon guide roller 8 are fitted to each other, and the retaining rings 15 are fixed to both ends of the ribbon guide roller 8 projecting to both sides of the locking piece 10, so that as shown in FIG. Is assembled.

Next, the structure of the head pressing / releasing mechanism 17 for bringing the head unit 16 into contact with and separating from the platen 2 will be described with reference to FIGS. 1, 3 and 4. The head pressing / releasing mechanism 17 includes a center shaft 18 driven by a head lift motor (not shown).
And a pressing plate 19 fixedly fitted to the center shaft 18. One end of a spring 20 that presses the head support 4 is held on both sides of the inner surface of the pressing plate 19, and a circular hole 22 into which a screw 21 is inserted is formed in the central portion. A screw 23 screwed into the head support 4 is formed at one end of the screw 21, and a flange 24 is formed at the other end. At the center of the center shaft 18, there is formed an annular groove 26 that detachably holds a semicircular mounting piece 25 formed at the center of the head support 4. The outer diameter of the bottom portion of the annular groove 26 is set to be slightly smaller than the semicircular inner diameter of the mounting piece 25, and the width of the annular groove 26 is set to be slightly larger than the plate thickness of the mounting piece 25. ing. As a result, the head support 4 has the head pressing / releasing mechanism 1 with a predetermined play in the direction in which the parallelism with the platen 2 changes.
7 is connected. Both ends of the center shaft 18 are rotatably supported by support members 27 as shown in FIGS.

In such a configuration, in FIG.
By rotating the center shaft 18 together with the pressing plate 19 in the counterclockwise direction, the pressing plate 19 is rotated by the screw 21.
The head unit 16 is separated from the platen 2 because the flange 24 is pressed to the right. In this state, a sheet (not shown) and an ink ribbon (not shown) can be inserted between the platen 2 and the thermal head 1.

After that, when the center shaft 18 and the pressing plate 19 are rotated clockwise, the spring 20
Is compressed, and the thermal head 1 presses the paper on the platen 2 and the ink ribbon by the compression force. In this state, by driving the thermal head 1, the ink of the ink ribbon is transferred to the paper. That is, printing is performed. The paper is conveyed by a feed roller (not shown), and the ink ribbon is wound by a ribbon reel (not shown). Therefore, the paper and the ink ribbon are separated on the ribbon guide roller 8.

By the way, since the locking pieces 10 having the notches 7 are integrally formed on both sides of the head support 4 for supporting the thermal head 1, the head support 4 and the position of the notch 7 with respect to the head support 4 are formed. The relationship is accurately defined. On the other hand, due to the play between the annular groove 26 of the center shaft 18 and the mounting piece 25, the head support in the direction in which the parallelism with respect to the platen 2 changes even when the head support 4 is connected to the head pressing / releasing mechanism 17. Since the movement of the body 4 is allowed, the parallelism between the platen 2 and the heat generation line 1a of the thermal head 1 is easily determined by fitting the left and right cutouts 7 into the bearing 3 of the platen 2. In addition, even when the dimensional variation of the head support 4 exceeds the allowable range, the mounting screw 6 is loosened to adjust the protruding length of the adjusting screw 13 from the lower surface of the bending piece 11, and the lower end of the adjusting screw 13 is again adjusted. By abutting the abutting portion 12 of the thermal head 1 and refastening the mounting screw 6, the parallelism between the heating line 1a of the thermal head 1 and the straight line connecting the notch 7 is corrected in units of the head unit 16. .

Further, when the paper and the ink ribbon are separated on the ribbon guide roller 8, the paper may be pulled by the adhesive force of the ink ribbon. In this case, if the axis of the ribbon guide roller 8 is not parallel to the platen 2, the sheet will be fed obliquely.

However, according to this embodiment, the bearing 3
The notch 7 and the ribbon guide roller 8 fitted to the bearing 1
Since the bearing fitting hole 9 that supports the through hole 4 is formed integrally with the locking piece 10 in the head support body 4, the notch 7
It is possible to accurately determine the degree of parallelism between the straight line connecting the lines and the line connecting the bearing fitting holes 9. Therefore, the platen 2 and the ribbon guide roller 8 are maintained parallel to each other, whereby the paper and the ink ribbon that have passed through the platen 2 can be separated on the ribbon guide roller 8 that is perpendicular to the paper transport direction. Therefore, skew of the paper can be prevented.

Next, a second embodiment of the present invention will be described with reference to FIGS. The same parts as those in the above embodiment are designated by the same reference numerals, and the description and the drawings are omitted. Square mounting holes 28 are formed on both sides of the head support 4 as mounting portions for mounting the thermal head 1 with the mounting screws 6.
A quadrangular collar 29 as a fine adjustment member fitted in these mounting holes 28 is provided. These color 2
9 has a through hole 30 having a size substantially equal to the thickness of the mounting screw 6, but the distance from the center of the through hole 30 to the four sides is changed stepwise. The mounting screw 6 is inserted into the through hole 30 and screwed into the screw hole formed on the back surface of the thermal head 1.
It is sized to cover the surroundings.

In such a structure, the relative positional relationship between the thermal head 1 and the mounting screw 6 screwed to the thermal head 1 is fixed, and one side of the collar 29 is brought into contact with the upper edge or the lower edge of the mounting hole 28. In this state, the mounting screw 6 inserted into the through hole 30 of the collar 29 is screwed into the thermal head 1, so that the head support 4 is held between the head of the mounting screw 6 and the thermal head 1. That is, the thermal head 1
And the head support 4 are assembled. In this case, a straight line connecting the heat generating line 1a of the thermal head 1 and the centers of the left and right cutouts 7 when assembled in a state in which one side of the collar 29 defined by design is in contact with the upper edge or the lower edge of the mounting hole 28. And are parallel to each other.

However, in manufacturing, when the variation in the size of the thermal head 1 or the head support 4 exceeds the allowable range, the position of the collar 29 in the mounting hole 28 is set to 9 mm.
The relative position of the thermal head 1 with respect to the head support 4 is changed by changing the angle by 0 ° and selecting the side that contacts the upper edge of the mounting hole 28. Thereby, the heating line 1a
And the parallelism with the straight line connecting the centers of the left and right cutouts 7 is finely adjusted. In order to perform such fine adjustment, a polygonal collar or a circular collar such as an eccentric cam (not shown) may be used in place of the square collar 29.

The adjusting screw 13 in the first embodiment
And the fine adjustment by the color 29 in the second embodiment,
The head unit 16 may be adjusted by using a jig or the like, or the notch 7 of the locking piece 10 may be fitted to the bearing 3 of the platen 2 and may be adjusted while checking the print result. Further, since the bearings 3 that rotate smoothly as concentric circles are used near both ends of the platen 2, it is possible to smoothly fit the notches 7 and the bearing 3 by the rotational movement of the bearing 3 when the bearing 3 is fitted. Of course, the same effect can be obtained by rotatably fitting a cylindrical member instead of the bearing 3 in the vicinity of both ends of the platen 2.

[0026]

According to the present invention, as described above, since the locking pieces having the notches are integrally formed on both sides of the head supporting body for supporting the thermal head, the head supporting body and this head supporting body are formed. The positional relationship of the notch with respect to can be accurately determined, and on the other hand, even when the head support is connected to the head pressing / releasing mechanism, the movement of the head support in the direction in which the parallelism to the platen changes is allowed. By fitting the left and right cutouts to the concentric circles of the platen, the parallelism between the platen and the heat generation line of the thermal head can be easily determined, and the variation in the size of the head support exceeds the allowable range. In this case, by operating the fine adjustment member, it is possible to correct the parallelism between the heating line of the thermal head and the straight line connecting the cutout in units of the head unit. That.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a relationship between a head unit and a head pressing / releasing mechanism according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a head unit.

FIG. 3 is a side view showing a relationship between a head unit and a head pressing / releasing mechanism.

FIG. 4 is a rear view showing the relationship between the head unit and the head pressing / releasing mechanism.

FIG. 5 is a perspective view of a head support according to a second embodiment of the present invention.

FIG. 6 is a rear view of the head support.

[Explanation of symbols]

 1 Thermal Head 2 Platen 3 Concentric Circle Part 4 Head Support 5 Mounting Part 7 Notch 10 Locking Piece 13 Fine Adjusting Member 16 Head Unit 17 Head Pressing / Release Mechanism 28 Mounting Part 29 Fine Adjusting Member

Claims (1)

[Claims] 1. A head support body removably connected to a platen pressing / releasing mechanism that is movable in and out of contact with a platen in a direction in which parallelism with the platen changes, with a predetermined play, and the head supporter. A thermal head that is displaceably assembled to a mounting portion formed on the body and faces the platen; and a notch that is detachably fitted to concentric circles coaxially arranged near both ends of the platen. In a direction in which a pair of left and right locking pieces integrally formed on both sides of the head support and a heating line formed by a large number of heating elements arranged in the thermal head are parallel to a straight line connecting the centers of the notches. A thermal head supporting device, wherein a head unit is formed by a fine adjustment member for finely adjusting the position of the thermal head with respect to the head support.