JPS646954B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention is directed to a printing hammer as disclosed in Japanese Patent Application Laid-open No. 51-40221 or a printing wire as disclosed in Japanese Patent Publication No. 52-5250, and a driving means for driving these. This invention relates to a dot printer that moves a hammer bank back and forth along a printing position and prints during the process of this back and forth movement.

[Background of the Invention] In a dot line printer that moves the hammer bank back and forth along the printing position and drives the printing hammer etc. during this back and forth movement to print, the hammer bank has a large mass and a large moving speed. It is necessary to provide a counterweight to offset the inertial force of the bank to minimize printer vibration.

A configuration devised for reciprocating the hammer bank and counterweight in opposite phases will be described with reference to FIGS. 3 and 4.

A camshaft 1 rotatably supported by a frame 2 via a bearing 3 is rotationally driven by a motor 11 via a driven pulley 7, a belt 9, and a drive pulley 10. A flywheel 8 is attached to the rear end of the camshaft 1 to reduce rotational fluctuations of the camshaft 1.
A pair of substantially elliptical cams 5 and 6 are mounted on the front end of the camshaft 1 so that their major axes are perpendicular to each other.

The camshaft 1 is supported by the frame 2 via a linear slide bearing 4 so as to be able to reciprocate in a direction perpendicular to the camshaft 1, and is mounted on two guide shafts 20 and 30 provided above and below the camshaft 1, respectively. The C-shaped slides 21 and 31 each have two arms extending on both sides in a direction perpendicular to the cam shaft 1 of the cams 5 and 6. Rollers 22 and 32 are rotatably attached to the ends of the arms via nuts 23 and 33, respectively. The arm of the upper slider 21 extends downward so that its pair of rollers 22 abut against the rear cam surface of the first cam 5 and the front cam surface of the second cam 6, respectively. Also, the lower slider 31
The arm extends upward such that the pair of rollers 32 abut the front cam surface of the first cam 5 and the rear cam surface of the second cam 6, respectively.

Bolts 24 and 3 are attached to the front of the sliders 21 and 31.
L-shaped holders 25 and 35 are respectively attached via 4. A hammer bank 40 and a counterweight 50 are attached to arms extending forward of the holders 25, 35 via blocks 26, 36. The hammer bank 40 holds a plurality of printing hammers indicated by reference numerals 41 provided along the printing position and a driving means for driving the printing hammers. The mass of the counterweight 50 is set to be approximately equal to the total mass of the hammer bank 40 including the printing hammer, its driving means 41, and the like.

The platen 60 is provided along the printing position so as to face the printing hammer via the paper 61 and the ink ribbon 62.

The rollers 22, 32 are connected to the cam 5, as described above.
Since it is in contact with the cam surfaces on both sides of camshaft 1
When the sliders 21 and 31 rotate, the sliders 21 and 31 reciprocate horizontally in opposite directions in FIG. 4. That is, each time the cams 5 and 6 rotate once, the sliders 21 and 31 reciprocate twice. Accordingly, the hammer bank 40 and the counterweight 50 also reciprocate together with the sliders 21 and 31 in directions perpendicular to the plane of the paper in FIG. 3 in opposite directions, that is, in opposite phases. As a result, hammer bank 40
Since the mass and acceleration of the counterweight 50 and the counterweight 50 are the same, the counts are balanced against each other and the printer does not vibrate.

Although the above configuration almost eliminates printer vibration caused by the reciprocating movement of the hammer bank,
There are new problems as shown below.

As described above, the hammer bank 40 and the counterweight 50 reciprocate with a phase difference of 180 degrees, canceling out reaction forces generated by acceleration and preventing the entire printer from vibrating. However, the counteracting reaction force is only in the acceleration direction of the hammer bank 40 and the counterweight 50;
Couples due to reaction forces cannot cancel each other out.

Figure 5 is a model of the mass arrangement of the reciprocating members in Figure 3, where GB and MB are hammer banks 4
Indicates the center of gravity and mass of 0. Similarly, GW and MW are the center of gravity of counterweight 50, mass, GSU,
MSU is the center of gravity, mass and GSL of the slider 21,
MSL indicates the center of gravity and mass of the slider 31, respectively.
Since it is a counterbalance mechanism, (MB+
MSU) = (MW + MSL).

GU indicates the entire center of gravity including the hammer bank 40, slider 21, holder 25, etc., and GL indicates the entire center of gravity including the counterweight 50, slider 31, holder 35, etc. As is clear from the figure, the centers of gravity GU and GL are far apart. Since the hammer bank 40 and the counterweight 50 accelerate in opposite directions perpendicular to the plane of the paper as described above, a force couple is generated by the reaction. When the acceleration of the hammer bank 40 and the counterweight 50 is α, the generated couple M is as follows.

M=α×(MB+MSU)× This force couple M causes the printer to vibrate at the reciprocating period of the hammer bank 40, thereby generating vibrations. Since the acceleration α increases in proportion to the square of the reciprocating speed, the higher the speed of the printer, the greater the force couple and the greater the vibration. Therefore, there is a drawback that it is difficult to increase the speed of the printer.

[Object of the Invention] The object of the present invention is to eliminate the drawbacks of the above-mentioned prior art, reduce the vibration caused by the couple by reducing the force couple to almost zero, and thereby enable higher speeds. It is.

[Summary of the Invention] The present invention focuses on the fact that as the distance between the centers of gravity GU and GL becomes smaller, the couple becomes smaller, and the present invention focuses on the fact that as the distance between the centers of gravity GU and GL becomes smaller, the couple becomes smaller, The present invention is characterized in that the positions of the hammer bank moving means and the counterweight moving means are set so that the lines connecting the centers of gravity of the means intersect with each other.

[Embodiments of the invention] FIG. 1 is a diagram showing an embodiment of the present invention.

The hammer bank 40 is attached to the block 8 by a holder 85 attached to the lower slider 31 via a bolt 84.
It is attached via 6. Further, the counterweight 50 is attached via a block 96 to a holder 95 attached to the upper slider 21 via a bolt 94.

Similar to FIG. 5, FIG. 2 is a model of the mass arrangement of the reciprocating members in the configuration shown in FIG.
Line connecting GSL and center of gravity GW of counterweight 50
The lines connecting GSU and the center of gravity of the slider 21 intersect near the center in the vertical direction.

Therefore, as is clear from the figure, the center of gravity GL of the entire body including the hammer bank 40, slider 31, holder 85, etc. and the center of gravity GU of the entire body including the counterweight 50, slider 21, holder 95, etc. are very close to each other. The distance between the centers of gravity becomes almost zero. Therefore, the couple M also becomes almost zero.

In other words, with the configuration shown in FIG. 1, not only can the reaction force in the acceleration direction be canceled out, but also the couple due to the reaction force can be canceled out, and even if the reciprocating speed of the hammer bank 40 becomes high, it can be canceled out. This makes it possible to increase the speed.

[Effects of the Invention] As described above, according to the present invention, vibrations caused by force couples can be reduced to almost zero, making it possible to increase the speed of the printer. Furthermore, since vibrations can be reduced, noise can be reduced and a quiet printer can be achieved.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing one embodiment of the main part of the present invention, Fig. 2 is a front view modeling and showing the mass arrangement of the reciprocating member shown in Fig. 1, and Fig. 3 is a proposal made before the present invention. FIG. 4 is a side view of FIG. 3 seen from the hammer bank side, with the lower slider lowered for ease of understanding. Fifth
This figure is a front view showing a model of the mass arrangement of the reciprocating member shown in FIG. 3. In the figure, 1 is a camshaft, 5 and 6 are cams, 11 is a motor, 21 and 31 are sliders, 40 is a hammer bank, 50 is a counterweight, and 85 and 95 are holders.

Claims (1)

[Scope of Claims] 1. A hammer bank holding a plurality of printing hammers arranged in line along a printing position and a driving means for driving the printing hammers is reciprocated along the printing position, and the reciprocating movement is A dot printer provided with a counterweight that is moved back and forth in an opposite phase to the hammer bank so as to print in the process and cancel the inertial force of the hammer bank, the bank moving means for moving the hammer bank back and forth, and the counterweight. and a weight moving means for reciprocating the bank moving means and the weight moving means, and the positions of the bank moving means and the weight moving means are determined by a line connecting the respective centers of gravity of the hammer bank and the bank moving means and the respective centers of gravity of the counterweight and the weight moving means. and the center of gravity of the hammer bank and the bank moving means as a whole and the center of gravity of the counterweight and the weight moving means as a whole in a direction perpendicular to the reciprocating direction of the hammer bank. A dot printer.