JPH07382B2 - Printer platen position adjustment mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention is directed to heat generation of an impact printer, particularly when an impact line printer having a print head having a large number of electromagnetically driven printing hammers that easily generates heat is continuously operated. The ambient temperature inside the device rises, and the gap between the platen and the print head tip is narrowed due to thermal expansion of the platen and the like, which makes it impossible to perform the printing operation. A shape memory alloy that is provided with a rotation lever on an eccentric cam that adjusts the position, the shape is displaced between the rotation lever and the base in response to a temperature above a certain environmental temperature, and the shape is restored to the original shape below the temperature. Between the platen and the tip of the print head by automatically rotating the eccentric cam by the position adjusting member that is displaced in response to changes in environmental temperature. Always it is obtained by adapted to be adjusted to within a predetermined range.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a platen position adjusting mechanism of a printer, and particularly in an impact type line printer having a large number of printing hammer mechanism parts that easily generate heat, a platen and a head tip which change depending on an environmental temperature. The present invention relates to a platen position adjusting mechanism that can always adjust the gap of the platen to within an allowable value.

In impact type printers equipped with printing hammers, particularly impact type line printers equipped with many printing hammers that are widely used as output devices for processing results of information data in computer systems The electromagnetic drive units that drive the printers are also mounted at high density, and it is inevitable that the environmental temperature inside the device will rise due to the heat generated by these electromagnetic drive units during printing operation. There is a problem that the gap with the tip of is changed.

Therefore, a simple mechanism that can always adjust the gap between the platen and the tip of the head, which changes depending on the environmental temperature, within an allowable value is required.

[Conventional technology]

In general, an impact type line printer is provided with a large number of printing hammers which face a platen 2 along a continuous printing sheet 1 and are supported on a head swing shuttle 6 via an ink ribbon 4 as shown in FIG. And a print head 3 including an electromagnetic drive unit for driving these units.

The continuous printing paper 1 is intermittently transferred by the tractor 5, and the head swing shuttle 6 and the printing head 3 are driven to print.

A conventional platen position adjusting mechanism for adjusting the gap between the platen 2 and the tip of the print head 3 in such a line printer is a platen support shaft 2a for supporting and rotating the platen 2 as shown in FIG. The eccentric cam 7 is rotatably arranged in contact with the eccentric cam 7, and the platen 2 is moved in parallel with the print head 3 by rotating the eccentric cam 7 so that the gap between the platen 2 and the tip of the print head 3 is increased. It is adjusted to a certain level.

[Problems to be solved by the invention]

However, when the line printer in which the gap between the platen 2 and the tip of the print head 3 is adjusted to be constant by the conventional platen position adjusting mechanism is continuously operated for printing, a large number of printing hammers in the print head 3 are driven by electromagnetic waves. The driving unit generates heat and the environmental temperature inside the printer rises.

This temperature rise has a drawback that the platen or the head member expands and the gap between the platen 2 and the tip of the print head 3 changes.

If this phenomenon also becomes excessive, the above-mentioned gap becomes so narrow that the continuous printing paper 1 and the ink ribbon 4 cannot be transferred normally, and printing is impossible.

In view of such conventional drawbacks, the present invention automatically rotates the eccentric cam when the environmental temperature inside the printer becomes a certain temperature or more by a simple configuration, and always maintains the gap between the platen and the head tip that changes depending on the environmental temperature. It is an object of the present invention to provide a new platen position adjusting mechanism for a printer, which can be adjusted within an allowable value suitable for printing.

[Means for solving problems]

In order to achieve the above object, the present invention is directed to a platen support shaft 2a for supporting and rotating the platen 2 facing the print head 3, the ink ribbon 4 and the continuous printing paper 1 as shown in FIG. The rotation lever 21 is provided on the eccentric cam 7 that is disposed so as to abut, and the shape is displaced between the rotation lever 21 and the base 22 provided on the eccentric cam 7 in response to a temperature equal to or higher than a certain environmental temperature, A spring-like position adjusting member 23 made of a shape memory alloy that restores its original shape at a temperature below the temperature.
Is provided.

[Work]

In the platen position adjusting mechanism of the printer of the present invention, the shape is displaced between the rotation lever 21 provided on the eccentric cam 7 and the base 22 in response to a temperature equal to or higher than a certain ambient temperature, and the original shape is maintained at a temperature lower than the temperature. Since the spring-like position adjusting member 23 made of a shape memory alloy that restores to the temperature is provided, the platen and the like naturally expand when the environmental temperature inside the printer exceeds a certain temperature. The spring-like position adjusting member 23 also moves in response to the ambient temperature, for example, in the extending direction (or in the contracting direction) to automatically rotate the rotation lever 21 and minutely rotate the eccentric cam 21.

As a result, the platen 2 moves in parallel to the print head 3 in the direction in which it spreads, and the gap between the platen 2 and the tip of the print head 3 can be adjusted to a predetermined gap.

Further, when the environmental temperature inside the printer falls below a certain temperature, the spring-like position adjusting member 23 made of the shape memory alloy is restored to its original shape, and the eccentric cam 21 is automatically rotated by rotating the lever 21 for reverse rotation. Is slightly rotated to restore the gap between the platen 2 and the tip of the print head 3 to the predetermined gap when initially adjusted, and the gap between the platen and the tip of the head is not affected by the ambient temperature, It can be maintained within a predetermined tolerance.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic side view showing an embodiment of a platen position adjusting mechanism of a printer according to the present invention.

In the figure, 2 is a platen which is rotatably supported by a platen support shaft 2a, and 3 is a print head which is opposed to the platen 2 with an ink ribbon 4 and a continuous print sheet 1 at a constant gap. .

Reference numeral 7 denotes an eccentric cam which is disposed in contact with the platen support shaft 2a in order to dispose the platen 2 facing the print head 3 with a constant gap.

A rotation lever 21 is fixedly arranged on the eccentric cam 7, and the shape is displaced between the rotation lever 21 and the base 22 in response to a temperature higher than a certain ambient temperature higher than room temperature and below the temperature. A spring-shaped position adjusting member 23 made of a shape memory alloy that restores to its original shape, and in this embodiment, is stretched in response to a temperature above a certain environmental temperature higher than room temperature and contracts and returns to its original shape below that temperature. A spring-like position adjusting member 23 made of a shape memory alloy is provided.

In addition, with respect to the support shaft 2a of the platen 2 in the above configuration,
The relationship between the eccentric cam 7 arranged in contact with the rotating lever 21 for rotating the eccentric cam 7 is that of the eccentric cam 7 contacting the support shaft 2a of the platen 2 as the rotating lever 21 rotates in the direction of arrow A. It is necessary to make the diameter, that is, the diameter from the center of rotation of the eccentric cam 7 to the contact point with the platen support shaft 2a short. Further, it is important that the degree of expansion and contraction of the spring-shaped position adjusting member 23 made of a shape memory alloy, which is sensitive to the ambient temperature, is matched with the amount of thermal expansion of the platen 2.

Next, the function of the platen position adjusting mechanism having the above configuration will be described.

When the line printer equipped with such a platen position adjusting mechanism is continuously operated for printing, the electromagnetic driving unit for driving a large number of printing hammers in the print head 3 generates heat, and the environmental temperature inside the printer rises. At this time, as shown in FIG. 2, for example, the platen 2 thermally expands as shown by a chain line, and the gap between the platen 2 and the tip of the print head 3 is narrowed in the conventional case. A spring-like position adjusting member 23 made of the shape memory alloy provided between the rotation lever 21 and the base 22 in parallel with the same also extends in response to the temperature, and the rotation lever 21 is moved in the direction of arrow A. Rotate.

The rotation of the rotation lever 21 causes the eccentric cam 7 to rotate in the minor axis direction to retract the platen 2, and the gap between the platen 2 and the tip of the print head 3 is automatically corrected to a predetermined gap.

Further, when the environmental temperature inside the printer drops to, for example, room temperature and the thermal expansion of the platen 2 returns to its original state, the spring-shaped position adjusting member 23 made of the shape memory alloy also contracts at this time, and the rotation lever 21 moves in the arrow direction. The platen 2 is rotated in the direction opposite to A, the eccentric cam 7 is rotated in the major axis direction, the platen 2 advances, and the gap with the front end of the print head 3 is automatically returned to the original predetermined gap.

As described above, according to the mechanism of this embodiment, even if the environmental temperature inside the printer changes, the gap between the platen 2 and the tip of the print head 3 is always defined by utilizing the change in the environmental temperature in reverse with a simple configuration. It is possible to automatically adjust and maintain the predetermined gap with allowance.

Incidentally, in the above embodiment, as the spring-shaped position adjusting member 23,
The case of using a shape memory alloy in which the shape is elongated in response to a temperature equal to or higher than a certain ambient temperature higher than room temperature and shrinks and restores to the original shape at the temperature or lower is described, but the present invention has such characteristics. It is not limited to shape memory alloys,
For example, it is needless to say that a shape memory alloy that is capable of shrinking its shape in response to a temperature equal to or higher than a certain ambient temperature higher than room temperature and recovers its original shape at the temperature or lower can be applied.

The shape of the position adjusting member 23 made of a shape memory alloy is not limited to the spring shape described in the present embodiment, and it is needless to say that various modifications can be made.

〔The invention's effect〕

As is clear from the above description, according to the platen position adjusting mechanism of the printer according to the present invention, the space between the platen and the tip of the print head is narrowed due to the thermal expansion of the platen or the like accompanying the increase of the environmental temperature inside the printer. The problem that the printing operation becomes difficult is solved by a simple configuration, and it is possible to automatically adjust and maintain the gap between the platen and the tip of the print head at a predetermined gap that always has a specified tolerance. Have advantages.

Therefore, various impact type serial printers that use an electromagnetically driven print head, in which the environmental temperature inside the device easily rises,
Alternatively, it is extremely advantageous when applied to various impact type line printers, and exhibits excellent effects in practical use.

[Brief description of drawings]

FIG. 1 is a schematic side view showing an embodiment of a platen position adjusting mechanism for a printer according to the present invention, and FIG. 2 is a schematic side view for explaining an embodiment of the operation of a platen position adjusting mechanism for a printer according to the present invention. A side view, FIG. 3 is a schematic perspective view for explaining an impact type line printer, and FIG. 4 is a schematic side view for explaining a platen position adjusting mechanism of a conventional printer. In FIGS. 1 and 2, 1 is a continuous printing paper, 2 is a platen, 2a is a platen support shaft, 3 is a print head, 4 is an ink ribbon, 7 is an eccentric cam, 21 is a rotation lever, and 22 is a base. , 23 are position adjusting members, respectively.

Claims (1)

[Claims] 1. A mechanism for adjusting a gap between a front end of a print head (3) and a platen (2) facing the print head (3) by rotating an eccentric cam (7) abutting on a platen support shaft (2a). 7) is provided with a rotation lever (21), and the shape is displaced between the eccentric cam (7) and the base (22) in response to a temperature equal to or higher than a certain ambient temperature, and the shape returns to the original shape at a temperature lower than the temperature. Position adjustment member (23) made of shape memory alloy to be restored
Is provided, and the eccentric cam (7) is automatically rotated by the position adjusting member (23) which is displaced in response to a change in environmental temperature, so that the gap between the platen (2) and the tip of the print head (3) is always kept. A platen position adjusting mechanism for a printer, which adjusts to a constant gap.