JPH0312524Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing hammer drive device used in a dot printer such as that disclosed in Japanese Patent Application Laid-Open No. 51-40221.

As shown in FIG. 3, the printing hammer driving device includes a printing hammer consisting of a plate spring 5 having a printing pin 6 and a plunger 7 made of magnetic material attached to the printing surface and the back surface thereof, respectively, a permanent magnet 1, a front yoke 2,
It consists of a rear yoke 3 and a release coil 4 wound around an upper leg portion or pole portion 31 of the rear yoke 3, and a magnetic circuit structure that attracts and holds the plunger 7 or leaf spring 5. Note that the lower end of the plate spring 5 is connected to the fixing screw 8.
It is attached to the lower end of the yoke spacer 9 via.

The leaf spring 5 is always attracted and held by the pole portion 31 of the rear yoke 3 by the magnetic attraction force of the permanent magnet 1. When the release coil 4 is energized, the magnetic attraction force is canceled out, and the leaf spring 5 flies due to its elastic force, causing the printing pin 6 to collide with a platen (not shown) via a sheet of paper (not shown) and an ink ribbon (not shown). As a result, dots are printed on the paper.

A plurality of such printing hammer drive devices are arranged in the row direction to form a hammer bank, and the hammer bank is reciprocated in the row direction and the paper is intermittently fed one dot row at a time for printing.

The printing hammers are arranged in the row direction at approximately equal intervals. For this reason, the shapes of the rear yoke 3 and the yoke spacer 9 are minimized, and their lengths are equal to the distance that the printing hammers are lined up.

As described above, the hammer bank is reciprocated by a drive source (not shown), so increasing the speed of such a printer is to shorten the period of this reciprocating movement. However, if the weight of the hammer bank is large, a large capacity drive source is required and it is difficult to achieve high speed. In other words, reducing the weight of the hammer bank is essential for increasing speed. However, in order to reduce the weight of the hammer bank, that is, the printing hammer drive device, the rear yoke 3 and yoke spacer 9 are constructed with a minimum cross-sectional area so as not to saturate the passage of magnetic flux, but the bending rigidity in the longitudinal direction of the hammer bank decreases. However, the hammer bank, that is, the hammer drive device is deformed by the reaction force during printing and the collision force when the leaf spring 5 returns to the pole 31, and the initially set distance between the printing pin 6 and the platen changes. As a result, the printing hammer did not exhibit desired operating characteristics, resulting in problems such as printed dots becoming thin or, in the worst case, no printing at all.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to improve the cooling effect of the printing hammer drive device.

In order to improve the rigidity of the printing hammer drive device, the present invention adds a member to the printing hammer drive device that is sufficiently rigid against deformation directions that are inconvenient for printing, and also changes the shape of the additional member to accommodate the increased rigidity. This design is designed to minimize the increase in mass due to the pressure drop and to make the temperature rise of the printing hammer drive device uniform in the longitudinal direction. The present invention will be described below with reference to the drawings.

1 and 2 show an embodiment of the present invention, and the same reference numerals as in FIG. 3 above indicate the same parts. A reinforcing plate 10 extending in the longitudinal direction, that is, along the printing position, is attached to a screw 1 below the yoke spacer 9.
It is attached via 1. The reinforcing plate 10 has a shape that is very long in the longitudinal direction relative to its thickness in order to sufficiently improve rigidity and minimize increase in weight. That is, as shown in FIG. 2, the reinforcing plate 10 has a wing shape in which the width in the direction perpendicular to the longitudinal direction widens from both ends toward the center, and the center part has a width of 1/3 to 1/3 of the total length in the longitudinal direction. The width is the same in the /4 range.

When all the printing hammers are driven, a reaction force is applied to the printing hammer driving device as described above, and the load form becomes a uniformly distributed load. However, for this loading condition, the weight increase is greater when the wing shape is used, such as a rectangular shape, etc. less than other shapes. Further, the temperature rise of the printing hammer drive device shows a distribution in which the temperature rise is large in the center and small at both ends, but since the reinforcing plate 10 is wing-shaped as described above and acts as a heat dissipation fin, the cooling effect in the center is The temperature increase distribution becomes almost uniform along the longitudinal direction.

As described above, according to the present invention, it is possible to improve the overall rigidity without increasing the weight of the printing hammer drive device, so that it is possible to increase the speed of the printer and eliminate the defective phenomenon of deterioration in print quality. In addition, as the temperature rise value in the center decreases and becomes uniform along the longitudinal direction, printing was previously restricted to prevent the temperature from rising above the specified value, but this restriction condition has been eased, so it becomes more uniform in the longitudinal direction. The printing speed can be improved.

[Brief explanation of the drawing]

1 and 2 are a sectional view and a perspective view showing an embodiment of the device of the present invention, and FIG. 3 is a sectional view showing an example of a conventional device. In the figure, 1 is a permanent magnet, 2 is a front yoke, 3 is a rear yoke, 31 is a pole, 4 is a release coil, 5 is a leaf spring, 6 is a printing pin, 7 is a plunger, 8 and 11 are fixing screws, and 9 is a yoke. Spacer,
10 is a reinforcing plate.

Claims (1)

[Claims for Utility Model Registration] 1. A permanent magnet extending along the printing position, a yoke spacer extending substantially parallel to the permanent magnet and provided in front of the permanent magnet, and a lower end attached to the yoke spacer. a leaf spring having a printed pin at its upper end; a rear yoke extending substantially parallel to the permanent magnet and provided on its rear surface; the rear yoke branches into at least a number equal to the number of leaf springs, the upper end of which A pole extending close to the back surface below the printing pin of the leaf spring,
1. A printing hammer driving device comprising a release coil wound around the pole, the printing hammer driving device comprising a reinforcing plate attached to the yoke spacer. 2. The printing hammer drive device according to claim 1, wherein the reinforcing plate has a shape that is very long in the longitudinal direction with respect to its thickness. 3. The printing hammer drive device according to claim 1, wherein the reinforcing plate is shaped like a wing.