JPH06286166A - Printing head for dot printer - Google Patents

Abstract

PURPOSE:To reduce an impact when an armature returns to a former position and to always stop the armature at an approximately constant former position irrespective of temperature increase. CONSTITUTION:A dot printer printing head 1 is provided with an armature 4 that is attracted by an electromagnetic drive means 5 for driving a printing wire 2 to a printing position and returned to a former position by a return spring 6 for driving the printing wire to a non-printing position and a cushioning member 8 for reducing an impact when the armature is returned to the former position. The cushioning member 8 is formed by overlapping a cushioning damper sheet 80 on a thickness correction plate 81 reducing in thickness in accordance with the thickness increase of the damper sheet caused by temperature increase. If the thickness of the damper sheet 80 is increased by temperature increase, the thickness of the thickness correction plate 81 substantially reduces to offset the increase of the thickness of the damper sheet. In this manner, the thickness of the cushioning member 8 can be always kept approximately constant irrespective of temperature increase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head for a dot printer.

[0002]

2. Description of the Related Art As a conventional print head for a dot printer, as shown in FIG. 5, for example, a printing position where a tip of a printing wire 60 fixed to a free end presses an ink ribbon (not shown) onto a printing paper surface. An armature 62 rotatable around the support shaft 61 between the end of the armature 62 and the original position (the non-printing position in FIG. 5) away from the ink ribbon, and the armature 62 wound around the core 63a (not shown). An electromagnetic drive means 63 for rotating the coil to the printing position by a magnetic attraction force generated when the coil is energized, a return spring 64 for returning the armature 62 to the original position, and a print head main body 65 and the armature 62. And a cushioning member 66 for cushioning an impact when the armature 62 returns to the original position, and the armature returning to the original position by the urging force of the return spring 64. 2 of impact is known which is configured to be alleviated by the buffer member 66.

[0003]

However, in the above-mentioned prior art, the cushioning member 66 is made of a material such as rubber, resin, or metal in the form of a sheet, and the cushioning member 66 expands due to a temperature rise to increase its thickness. Will end up. When the thickness of the cushioning member 66 increases as shown in FIG. 6 due to the temperature rise, the shock absorbing member 66 cushions the shock and stops the armature 62. Instead of returning to the printing position), as shown by the solid line in FIG. 6, it stops at a position displaced from the original position. As a result, when the armature 62 is returned to the original position, the printing wire 60 cannot be completely returned to the regular non-printing position, the tip thereof is caught by the ink ribbon, and malfunction occurs, or the armature 62 and the electromagnetic drive means 63. When the armature 62 is driven to the printing position by changing the distance between the core 63a and the core 63a, the magnetic attraction force acting on the armature 62 changes.
There was a problem that the force of pressing the ribbon at the leading edge of 0 was not constant, and high quality printing could not be performed.

The present invention has been made by paying attention to such conventional problems, and it is possible to reduce the impact when the armature returns to its original position (non-printing position) and to prevent the armature from increasing in temperature. It is an object of the present invention to provide a print head for a dot printer, which can always be stopped at a substantially constant original position.

[0005]

In order to achieve the above-mentioned object, according to the present invention, the printing wire is sucked by an electromagnetic driving means to drive the printing wire to a printing position and is returned to the original position by a return spring so that the printing wire is not moved. In a print head for a dot printer including an armature that drives to a printing position and a cushioning member that reduces the impact when the armature returns to its original position, the cushioning member includes a cushioning sheet for cushioning and a damper sheet for increasing temperature. Of at least one thickness correction plate, the thickness of which substantially decreases as the thickness of the plate increases.

As the thickness correction plate, a sheet formed of a material having a negative linear expansion coefficient, or a sheet having a large thickness that warps at room temperature and a small amount of warping according to a temperature rise, and the thickness substantially decreases. The bimetal thus formed is applicable.

[0007]

In the print head for a dot printer described above, the cushioning member includes a cushioning sheet for cushioning and at least one thickness correcting plate whose thickness is substantially reduced in accordance with an increase in the thickness of the damper sheet due to a temperature rise. As the thickness of the damper sheet increases due to the temperature rise, the thickness of the thickness correction plate is substantially reduced in response to this increase to offset the increase in the thickness of the damper sheet. As a result, the thickness of the cushioning member is always kept substantially constant regardless of the temperature rise.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In the description of each embodiment, the same parts will be denoted by the same reference numerals and redundant description will be omitted.

FIG. 1 shows a print head for a dot printer according to the first embodiment of the present invention. As shown in FIGS. 1 and 2, in a dot printer print head 1, a print position at which the tip of a print wire 2 fixed to a free end presses an ink ribbon (not shown) onto a printing paper surface and the tip thereof is an ink. An armature 4 which is rotatable around a support shaft 3 between an original position (non-printing position shown in FIG. 1) away from the ribbon, and an electromagnetic driving means for rotating the armature 4 to the printing position by a magnetic attraction force. 5, a return spring 6 for returning the armature 4 to the original position, and a cushioning member 8 arranged between the print head main body 7 and the armature 4 to mitigate the impact when the armature 4 returns to the original position. Is equipped with.

A coil (not shown) is wound around the core 5a of the electromagnetic drive means 5, and the magnetic attraction force generated when the coil is energized causes the armature 4 to move from the original position shown in FIG. 1 to the printing position. It is adapted to be rotated clockwise in the figure.

The cushioning member 8 is a damper sheet 80 for cushioning.
And a thickness correction plate 81 whose thickness decreases as the thickness of the damper sheet 80 increases due to the temperature rise. This cushioning member 8 is a damper sheet 80.
Are arranged on the lower side, that is, on the armature 4 side.

The thickness correction plate 81 is made of a material having a linear expansion coefficient opposite to that of the damper sheet 80, that is, a negative linear expansion coefficient whose sign is opposite to that of the damper sheet 80 and whose absolute value is substantially equal. It is a sheet. An example of such a thickness correction plate 81 is a negative linear expansion coefficient (−23.6).
There is a sheet formed of Fe-Pt alloy having / 10 ^-4 K ^-1 ).

The armature 4 and the core 5a are
A plurality of buffer members 8 are radially arranged, and the buffer member 8 is formed in a ring shape.

In the dot printer print head 1 of the first embodiment having the above-described structure, the cushioning member 8 has a cushioning damper sheet 80 and a thickness that decreases in accordance with an increase in the thickness of the damper sheet 80 due to a temperature rise. Since the correction plate 81 and the correction plate 81 are arranged so as to overlap each other, when the thickness of the damper sheet 80 increases due to a temperature rise, the thickness of the thickness correction plate 81 decreases by an amount corresponding to the increase in the thickness of the damper sheet 80. Then, the increase in the thickness of the damper sheet 80 is offset, so that the thickness L (see FIG. 2) of the cushioning member 8 is always kept substantially constant regardless of the temperature rise.

Therefore, the shock when the armature 4 is returned to the original position shown in FIGS. 1 and 2 is alleviated by the damper sheet 80 of the cushioning member 8 by the urging force of the return spring 6, and the armature 4 is cushioned by the cushioning member 8. As a result, it is always stopped at a substantially constant original position (non-printing position) regardless of the temperature rise. As a result, the magnetic attraction force of the armature 4 does not change due to the change in the distance between the armature 4 and the core 5a due to the change in the thickness of the cushioning member 8, which ensures that the print quality is always proper and of good quality regardless of the temperature rise. When the armature 4 is returned to its original position, the printing wire 2 can be returned to a substantially constant regular non-printing position regardless of the temperature rise. It is possible to prevent malfunctions such as catching on the ink ribbon.

FIG. 3 shows a print head 1 for a dot printer according to the second embodiment of the present invention. In the second embodiment, instead of the thickness correction plate 81 in the first embodiment, it is formed so that at normal temperature, the thickness is large and the amount of warp is small in accordance with the temperature rise, and the thickness is substantially reduced. The used bimetal 81 'is used. Other configurations are the same as those in the first embodiment.

As such a bimetal 81 ', for example, its warp amount changes constantly in the range of -20 ° C to 250 ° C (JIS, C-2530, Ni-Mn-Fe /
There is a bimetal of 38Ni-Fe).

In the dot printer print head 1 of the second embodiment having the above structure, the cushioning member 8 has a cushioning damper sheet 80 and a thickness substantially corresponding to the increase in the thickness of the damper sheet 80 due to the temperature rise. Since the thickness of the damper sheet 80 is increased by increasing the thickness of the damper sheet 80, the bimetal 81 'serving as a thickness correcting plate is arranged so as to overlap with the bimetal 81'. The warp amount of 81 'is reduced and the thickness thereof is reduced to offset the increase in the thickness of the damper sheet 80,
As a result, the thickness L (see FIG. 4) of the cushioning member 8 is always kept substantially constant.

Therefore, the shock when the armature 4 is returned to the original position shown in FIG. 3 by the urging force of the return spring 6 is mitigated by the damper sheet 80 of the cushioning member 8, and
The armature 4 is always stopped at the substantially constant original position (non-printing position) by the buffer member 8 regardless of the temperature rise. As a result, also in this embodiment, the magnetic attraction force of the armature 4 does not change due to the change in the distance between the armature 4 and the core 5a due to the change in the thickness of the buffer member 8 as in the first embodiment. With this, it is possible to always perform proper and high-quality printing regardless of the temperature rise, and when the armature 4 is returned to the original position, the printing wire 2 is always substantially constant regardless of the temperature rise. Back to the print wire 2
It is possible to prevent malfunctions such as the tip of the paper being caught in the ink ribbon.

The thickness compensating plate 81 in the first embodiment and the bimetal 81 'as the thickness compensating plate in the second embodiment may be arranged so as to overlap each other.

[0021]

As described above in detail, according to the print head for a dot printer of the present invention, the cushioning member has a cushioning sheet for cushioning, and the thickness of the cushioning sheet increases as the temperature of the damper sheet increases. Since it has a configuration in which at least one thickness correction plate that is substantially reduced is arranged in an overlapping manner,
When the thickness of the damper sheet increases due to the temperature increase, the thickness of the thickness correction plate substantially decreases in response to this increase, and the increase in the thickness of the damper sheet is offset, thereby increasing the thickness of the cushioning member regardless of the temperature increase. Without being kept almost constant. Therefore, the impact when the armature returns to the original position (non-printing position) can be mitigated, and the armature can always be stopped at the substantially constant original position regardless of the temperature rise. As a result, the magnetic attraction force of the armature does not change due to the change in the distance between the armature and the electromagnetic driving means due to the change in the thickness of the cushioning member, and thus, proper and high quality printing is always performed regardless of the temperature rise. Moreover, when the armature is returned to the original position, it is possible to prevent a malfunction such that the tip of the print wire is caught by the ink ribbon.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram illustrating a print head for a dot printer according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a schematic configuration diagram showing a print head for a dot printer according to a second embodiment of the present invention.

FIG. 4 is a partially enlarged view of FIG.

FIG. 5 is a schematic configuration diagram showing a conventional print head for a dot printer.

6 is a partially enlarged view of FIG.

[Explanation of symbols]

 1 Print Head for Dot Printer 2 Print Wire 4 Armature 5 Electromagnetic Drive Means 6 Return Spring 8 Cushioning Member 80 Cushioning Damper Sheet 81 Thickness Correction Plate 81 'Bimetal (Thickness Correction Plate)

Claims (3)

[Claims] 1. An armature that is suction-operated by electromagnetic driving means to drive a printing wire to a printing position and is returned to an original position by a return spring to drive the printing wire to a non-printing position, and the original position of the armature. In a print head for a dot printer, comprising: a cushioning member for cushioning a shock at the time of returning to a shock absorber, the cushioning member has a cushioning sheet for cushioning, and the thickness of the damper sheet is substantially increased according to an increase in the thickness of the damper sheet due to a temperature rise. A print head for a dot printer, characterized in that at least one thickness correcting plate, which is reduced in number, is arranged in an overlapping manner. 2. The print head for a dot printer according to claim 1, wherein the thickness correction plate is a sheet formed of a material having a negative linear expansion coefficient. 3. The thickness compensating plate is a bimetal formed so as to have a large thickness when warped at room temperature and a small amount of warping as the temperature rises to substantially reduce the thickness. A print head for a dot printer according to claim 1.