JPS62191165A - Mechanism for adjusting platen position of printer - Google Patents

Abstract

PURPOSE:To obtain the platen position adjusting mechanism of a printer capable of being always adjusted to within a tolerance suitable for printing, by adjusting the gap between the platen and the leading end of a printing head by automatically rotating an eccentric cam with a position adjusting member displacing in response to the change in environmental temp. CONSTITUTION:A platen 2 is supported in a rotatable menner by a platen support shaft 2a and a printing head 3 is arranged in opposed relation to the platen 2 through an ink ribbon 4 and continuous printing paper 1 so as to leave a constant gap. An eccentric cam 7 is arranged so as to be contacted with the platen support shaft 2a in order to arrange the platen 2 in opposed relation to the printing head 3 so as to provide the constant gap. A rotary lever 21 is fixedly arranged to said eccentric cam 7 and a spring like position adjusting member 23 comprising a shape memory alloy configurationally displacing in response to the temp. equal to or more than definite environmental temp. higher than ambient temp. and restored to the original shape at temp. equal to or less than said environmental temp. is provided between the rotary lever 21 and a base stand 22.

Description

[Detailed Description of the Invention] [Summary] The present invention provides a method for reducing heat generation in the print head when continuously operating an impact printer, particularly an impact line printer equipped with a print head that easily generates heat and has a large number of electromagnetically driven printing hammers. In order to solve the problem that the environmental temperature inside the device increases and the platen etc. thermally expands, the gap between the platen and the tip of the print head gets pinched and printing operation becomes impossible. A shape memory alloy that has a rotating lever installed on the eccentric cam that adjusts its position, and that changes its shape in response to temperatures above a certain environmental temperature and returns to its original shape at temperatures below that temperature. A position adjustment member is provided, and the eccentric cam is automatically rotated by the position adjustment member, which is displaced in response to changes in environmental temperature, so that the gap between the platen and the print head tip is always kept within a predetermined range. It is designed to be adjustable.

[Industrial application field]

The present invention relates to an improvement in the platen position adjustment mechanism of a printer, and in particular, in an impact-type line printer equipped with a large number of printing hammer mechanisms that are prone to heat generation, the gap between the platen and the head tip, which changes depending on the environmental temperature, is always maintained at an allowable value. This invention relates to a platen position adjustment mechanism that can be adjusted within the same range.

Impact type printers equipped with printing hammers, especially impact type line printers equipped with a large number of printing hammers, which are widely used as output devices for information data processing results in computer systems, are compatible with a large number of printing hammers. The electromagnetic drive units that drive these are also densely packaged, and the heat generated by these electromagnetic drive units during printing operations inevitably increases the environmental temperature inside the device. There is a problem that the gap between the head and the tip changes.

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

[Conventional technology]

In general, an impact type line printer has a large number of printed characters, which are supported on a head swinging shuttle 6 via an ink ribbon 4, facing a platen 2 along which a continuous printing paper 1 is placed, as shown in FIG. 3, for example. A print head 3 is arranged to include a hammer and an electromagnetic drive unit that drives the hammer.

The continuous printing paper 1 is intermittently transported by a tractor 5, and printing is performed by driving a head swinging shuttle 6 and a printing press 3.

A conventional platen position adjustment mechanism for adjusting the gap between the platen 2 and the tip of the print head 3 in such a line printer has a platen support shaft 2a that supports and rotates the platen 2, as shown in FIG. An eccentric cam 7 is rotatably disposed in contact with the print head 3, and by rotating the eccentric cam 7, the platen 2 is moved in parallel to the print head 3, thereby closing the gap between the platen 2 and the tip of the print head 3. It is constantly adjusted.

[Problem that the invention seeks to solve]

However, when a line printer, which uses a conventional platen position adjustment mechanism to adjust the gap between the platen 2 and the tip of the print head 3 to a constant value, continuously moves the print line, many print hammers in the print head 3 are driven. The electromagnetic drive unit generates heat, and the environmental temperature inside the printer rises.

This temperature rise causes the platen or the head member to expand, resulting in a change in the gap between the platen 2 and the tip of the print head 3.

When this phenomenon becomes excessive, the gap narrows significantly, causing problems in that the continuous printing paper 1 and the ink ribbon 4 cannot be transported normally, and printing is also impossible.

In view of these conventional drawbacks, the present invention has a simple configuration that automatically rotates an eccentric cam when the environmental temperature inside the printer exceeds a certain temperature to constantly maintain 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 novel printer platen position adjustment mechanism that can be adjusted to within a printing tolerance.

[Means for solving problems]

In order to achieve the above object, the present invention is directed to a platen support shaft 2a that supports and rotates a printing bed 3, an ink ribbon 4, and a platen 2 facing each other via a continuous printing paper 1, as shown in FIG. A rotating lever 21 is provided on the eccentric cam 7 which is placed in contact with the eccentric cam 7, and the shape is displaced between the rotating lever 21 provided on the eccentric cam 7 and the base 22 in response to a temperature above a certain environmental temperature, The structure includes a spring-like position adjustment member 23 made of a shape memory alloy that restores to its original shape at a temperature below this temperature.

[For production]

The platen position adjustment mechanism of the printer of the present invention has a configuration in which the shape is displaced between the rotating lever 21 provided on the eccentric cam 7 and the base 22 in response to a temperature above a certain environmental temperature, and returns to the original shape below the temperature. Since the spring-like position adjustment member 23 made of a shape memory alloy that restores its original shape is provided, when the environmental temperature inside the printer exceeds a certain temperature, the platen etc. naturally expand, but the shape memory alloy The spring-shaped position adjustment member 23 also responds to the environmental temperature and is displaced, for example, in the direction of extension (or in the direction of contraction), so that the rotation lever 2
1 is automatically rotated to slightly rotate the eccentric cam 21.

As a result, the platen 2 moves parallel to the print head 3 in a 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 adjustment member 23 made of the shape memory alloy is restored to its original shape, and the rotation lever 21 is automatically rotated in the opposite direction to prevent the eccentric cam 21 from rotating. By rotating the platen slightly, the gap between the platen 2 and the tip of the print head 3 is restored to the predetermined gap when it was first adjusted, and the gap between the platen and the tip of the spatula is not affected by the environmental temperature. It can always be maintained within predetermined tolerances.

〔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 adjustment mechanism of a printer according to the present invention.

In the figure, 2 is a platen rotatably supported by a platen support shaft 2a, and 3 is a print head disposed opposite to the platen 2 with an ink ribbon 4 and continuous printing paper 1 in between with a certain gap. .

Reference numeral 7 designates an eccentric cam that is placed in contact with the platen support shaft 2a in order to place the platen 2 facing the printing plate 3 with a certain gap therebetween.

A rotating lever 21 is fixedly disposed on the eccentric cam 7, and the shape is displaced between the rotating lever 21 and the base 22 in response to a temperature higher than a certain environmental temperature higher than room temperature, and when the temperature is lower than that temperature, the rotating lever 21 is fixedly arranged. A spring-like position adjustment member 23 made of a shape memory alloy that restores to its original shape; in this embodiment, it expands in response to a temperature above a certain environmental temperature that is higher than room temperature, and contracts and restores to its original shape below that temperature. A spring-like position adjustment member 23 made of a shape memory alloy is provided.

In addition, the relationship between the eccentric cam 7 placed in contact with the support shaft 2a of the platen 2 in the above configuration and the rotating lever 21 that rotates the eccentric cam 7 is as follows as the rotating lever 21 rotates in the direction of the arrow. It is necessary that the diameter of the eccentric cam 7 that comes into contact with the support shaft 2a of the platen 2, that is, the diameter from the rotation center of the eccentric cam 7 to the point of contact with the platen support shaft 2a, is the minor diameter. Further, it is important that the degree of expansion and contraction of the spring-like alignment member 23 made of a shape memory alloy, which is sensitive to the environmental temperature, is adjusted to the amount of thermal expansion of the platen 2.

Next, the function of the platen position adjustment mechanism configured as described above will be explained.

When a line printer equipped with such a platen position adjustment mechanism is operated for continuous printing, an electromagnetic drive section that drives a large number of printing hammers in the printing pad 3 generates heat, and the environmental temperature inside the printer rises. At this time, the second
As shown in the figure, for example, the platen 2 thermally expands as shown by the chain line, and in the conventional case, the gap with the tip of the printing bend 3 is narrowed, but in this embodiment, it rotates in parallel with the thermal expansion of the platen 2. The spring-like position adjusting member 23 made of the shape memory alloy provided between the lever 21 and the base 22 also extends in response to the temperature, and rotates the lever 21 for rotation in the direction of the arrow.

This rotation of the rotation lever 21 causes the eccentric cam 7 to rotate in the short diameter direction, causing the platen 2 to move backward, and the gap between it and the tip of the printing bend 3 to be automatically corrected to a specified 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-like position adjustment member 23 made of the shape memory alloy also contracts, causing the rotation lever 21 to move as shown in the arrow. The platen 2 is rotated in the direction opposite to A, and the eccentric cam 7 is rotated in the major axis direction to move the platen 2 forward, and the gap between the print head and the tip of the rad 3 is automatically returned to the original predetermined gap.

In this way, according to the mechanism of this embodiment, even if the environmental temperature inside the printer changes, the change in environmental temperature is reversely utilized with a simple configuration to increase the gap between the platen 2 and the tip of the 7-d 3. automatically adjusts to a predetermined gap with specified tolerances,
It becomes possible to maintain

In the above embodiments, the spring-like position adjustment member 23 is made of a shape memory alloy that expands in shape in response to a temperature above a certain environmental temperature higher than room temperature, and contracts and restores to its original shape below the temperature. Although the present invention is not limited to shape memory alloys having such characteristics, for example, the shape shrinks in response to a certain environmental temperature higher than room temperature, and Needless to say, it is possible to apply shape memory alloys that restore the original shape.

Further, the shape of the position adjustment member 23 made of a shape memory alloy is not limited to the spring shape described in this embodiment, but it goes without saying that it can be modified in various ways.

〔Effect of the invention〕

As is clear from the above description, according to the platen position adjustment mechanism of the printer according to the present invention, the distance between the platen and the print head tip narrows due to thermal expansion of the platen, etc. due to the increase in the environmental temperature inside the printer. The problem of difficult printing operations is solved by a simple configuration, and the gap between the platen and the print head tip αlid can be automatically adjusted and maintained at a specified gap with a specified tolerance (direction). Has excellent advantages.

Therefore, various impact type serial printers using electromagnetic drive type print heads, which tend to increase the environmental temperature inside the device,
Alternatively, it is extremely advantageous to apply to various impact type line printers, and has excellent practical effects.

[Brief explanation of drawings]

FIG. 1 is a schematic side view showing an embodiment of the platen position adjustment 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 the platen position adjustment mechanism for a printer according to the present invention. 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 adjustment mechanism of a conventional printer. In Figures 1 and 2, 1 is 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 shows the position adjustment member in Figure 1;

Claims (1)

[Claims] The gap between the tip of the print head (3) and the opposing platen (2) is divided by an eccentric cam (
In the mechanism adjusted by rotation of 7), a rotation lever (21) is provided on the eccentric cam (7), and a mechanism is provided between the eccentric cam (7) and the base (22) that is sensitive to a temperature above a certain environmental temperature. A position adjustment member (23) made of a shape memory alloy whose shape is displaced by a change in temperature and restored to its original shape at or below the temperature is provided, and the position adjustment member (23) which is displaced in response to changes in environmental temperature allows the eccentric cam to (7) automatically rotates,
A platen position adjustment mechanism for a printer, characterized in that the gap between the platen (2) and the tip of the print head (3) is always adjusted to a constant gap.