JP4433911B2 - Dot line printer - Google Patents

Description

  The present invention relates to a dot line printer. More specifically, the present invention relates to a shuttle mechanism that improves the coil cooling efficiency of a linear motor while simultaneously increasing the speed of the reciprocating motion of the shuttle mechanism.

  The prior art of the conventional dot line printer will be described with reference to FIGS. FIG. 3 is a schematic perspective view of a main part of a conventional dot line printer, and FIG. 4 is a front view of a shuttle mechanism.

  As shown in FIGS. 3 and 4, the dot line printer includes a hammer bank 21 on which a plurality of printing elements are mounted, and a shuttle mechanism unit for reciprocating the hammer bank 21 in the digit direction (arrow direction in FIG. 3). 50, a paper feed mechanism that conveys the printing paper 31, and a ribbon mechanism (not shown) that drives the ink ribbon 32, and drives the printing element during the reciprocating motion. By hitting the printing paper 31 via the ink, the ink is transferred to the printing paper 31 and printing is performed. The printing speed, which is the most basic specification of the printing apparatus, is determined by the responsiveness of driving of the printing element of the hammer bank 21 and the time of reciprocating movement of the shuttle mechanism 50. Accordingly, in order to increase the speed of the printing apparatus, it is important to increase the reciprocating motion of the shuttle mechanism 50, and therefore it is common to employ a linear motor system that is excellent in high-speed reciprocating motion. .

  The linear motor type shuttle mechanism 50 includes a bush 16 that holds the hammer bank 21, a hammer shift plate 12 that maintains reciprocating accuracy, a coil 14 that drives the linear motor, and a magnet 11 that prevents leakage of magnetic flux. It consists of three main parts of the yoke 10 that are attached to a sheet metal.

  Further, as shown in FIG. 4, the yoke 10 is disposed so as to sandwich the coil 14. Furthermore, as shown in FIG. 4, with respect to the configuration of the three parts, since the yoke is the most rigid in configuration, it is common to install it sideways so that all parts are installed on the yoke 10. The parts described below are arranged.

  First, the bush 16 that holds the hammer bank 21 and the hammer shift plate 12 that maintains reciprocating accuracy are connected to the timing belt 13 and bridge the front and rear of the coil 14 that is horizontally disposed between the yokes 10. The coil shift plate 15 is fixed to the timing belt 13.

  Furthermore, in order to increase the speed of the shuttle mechanism 50, it is necessary to use the magnetic flux of the magnet 11 with high efficiency, and the efficiency of the yoke 10 is suppressed by keeping the gap between the coils 14 to about 0.5 mm on both sides. The speed was well realized.

  Further, since the shuttle mechanism 50 moves at a high speed from side to side, it causes a large vibration in the printing apparatus. Therefore, as shown in FIG. 4, the reciprocating motion in the left and right directions is performed in opposite phases via the timing belt 13 on the hammer bank 21 side and the coil 14 side. And in order to cancel the reversal motion and offset the energy to reduce the vibration, the hammer side and the coil side have the same mass so that the energy at the time of reversal is reduced. For this reason, a weight may be loaded to match the mass in a form contrary to the increase in the speed of the shuttle mechanism 50, and the mass reduction of the movable part is a big problem for the shuttle mechanism 50.

  In order to increase the speed of the shuttle mechanism unit 50, increasing the current flowing through the coil 14 is also a great means. However, increasing the current increases the amount of heat generated by the coil 14, and thus it is necessary to cool it. Yes, the cooling problem is a big issue. As shown in FIG. 4, the gap between the yoke 10 provided with the magnet 11 of the shuttle mechanism 50 and the coil 14 as the heat generation source has a vertical gap of only about 0.5 mm as described above. It was a big obstacle to cooling. In order to send cooling air into this gap, the capacity of a blower (not shown) that sends cooling air is increased, or in order to send cooling air to the gap, the tip of a duct (not shown) is narrowed as much as possible to increase the wind speed. Such measures are necessary. However, increasing the wind speed has also caused adverse effects such as insufficient air volume. For this reason, it has been difficult to easily increase the current to the coil 14, which is an effective means for realizing high speed of the shuttle mechanism 50.

Japanese Patent Laid-Open No. 06-040047

  In the prior art, in order to increase the speed of the shuttle mechanism part, the target shuttle mechanism part reciprocating time is caused by problems such as mass balance problems and coil currents that cannot be increased easily due to coil cooling problems. It took a lot of effort to realize the shortening of

  The present invention reduces the weight on the coil side, eliminates the need for countermeasures contrary to high speed, such as adding a weight for mass balance, and improves the cooling efficiency of the coil to increase the current and shuttle mechanism. The purpose is to easily realize the high speed.

  In order to solve the above problems, the present invention provides a hammer bank in which a plurality of dot printing hammers are arranged and reciprocates in the digit direction, and a magnet attached to a yoke as a drive source for the hammer bank and linear motor. In the dot line printer of a linear motor type shuttle mechanism supported by a bush and a coil shift plate that slide on a guide shaft, the coil reciprocates in a phase opposite to that of the hammer bank. The yoke and the coil are installed so as to face each other in the vertical direction, and the coil is connected to the coil shift plate installed above in a cantilever state.

  Further, a cooling mechanism for generating cooling air for cooling the coil is provided, and a cooling air passage for sending the cooling air between the yoke and the coil is provided in the lower part of the coil.

  It is possible to simplify the structural parts by changing the yoke provided with the magnet from the conventional horizontal position to the vertical position, and to take measures by easily reducing the mass on the coil side. In addition, by placing the yoke vertically, the cooling air can be blown from the lower side of the yoke. Further, the heat of the coil naturally rises, and air convection occurs in a very natural manner, so that the cooling air from the lower side can be easily sent to the coil.

  The problem of speeding up the shuttle mechanism, that is, reducing the mass accompanying the simplification of the part structure and improving the cooling efficiency, is achieved by arranging the yoke vertically.

  The present invention will be described with reference to FIGS. FIG. 1 is a schematic side view of a shuttle mechanism unit according to an embodiment of the present invention, and FIG. 2 is a front view of the shuttle mechanism unit of the present invention.

  The configuration of the dot line printer of the present invention is almost the same as the conventional configuration except for the shuttle mechanism 50, and the description of the prior art can be used.

  The linear motor type shuttle mechanism 50 includes a bush 16 that holds the hammer bank 21, a hammer shift plate 12 that maintains reciprocating accuracy, a coil 14 that drives the linear motor, and a magnet to prevent leakage of magnetic flux. 11 is attached to a sheet metal, and the yoke 10 is disposed so as to sandwich the coil 14.

  Further, the yoke 10 is arranged vertically, the bush 16 for holding the hammer bank 21 and the hammer shift plate 12 for maintaining the accuracy of reciprocating motion are connected to the timing belt 13 and the guide shaft is slidably installed. The coil 14 is connected to the coil 14 in a cantilevered manner from above via a coil shift plate 15.

  In the present embodiment, the coil shift plate 15 is cantilevered so that the mass can be reduced to about 1/2 of the conventional mass (about 300 g reduction).

  Therefore, it can be confirmed from the following expression that the driving acceleration of the shuttle mechanism 50, which is important for speeding up, is improved.

F = ntBLI (1)
Here, F: thrust, n: number of effective conductors (number of yokes: 2), B: magnetic flux density of magnet, L: effective length of magnet, I: current.

F = ma (2)
Here, m: moving part weight, a: acceleration.

  If the above equation (1) has the same conditions, the thrust F is constant, and the acceleration is determined by the mass of the movable part from equation (2).

  In the configuration of the present embodiment, since a reduction of about 300 g can be achieved, the mass that no longer needs a mass balance with respect to the conventional movable part mass of 4.8 kg (value obtained by adding the hammer side and the coil side) When included, a reduction of about 600 g was achieved, and the mass of the movable part was about 4.2 kg. Therefore, an acceleration improvement of about 15% by mass ratio can be realized.

  In the case of the horizontal placement of the prior art, if the mass of the coil shift plate 15 is reduced or if it is attempted to reduce the mass in another part, the rigidity is lowered. Then, the print quality is deteriorated due to the breakage of the movable parts or the decrease in rigidity. Therefore, the configuration in which the yoke 10 is placed vertically is advantageous.

  Further, when the current flowing through the coil 14 is increased in order to increase the speed of the shuttle mechanism 50, the yoke 10 is placed vertically as in this embodiment, so that the yoke 10 provided with the magnet 11 and the heat source. There is no need to forcibly feed cooling air into the gap with the coil 14. In the case of this configuration, the heated hot air naturally rises and escapes from the coil 14 portion, and the cooling air is sent from the lower side, so that natural air convection is generated and the cooling efficiency is improved.

  In the cooling method of the prior art, much effort is required to optimize the duct shape (not shown), and the duct (not shown) is expensive. However, with the configuration of the present invention, the cooling efficiency is improved, and the improved current can be increased.

  From the above formula (1), since the thrust is improved by the current improvement ratio, this configuration is very effective for increasing the speed of the shuttle mechanism 50.

It is a schematic side view of the shuttle mechanism part which shows the Example of this invention. It is a schematic front view of the shuttle mechanism part which shows the Example of this invention. It is a perspective view which shows the conventional dot line printer. It is a front view which shows the conventional shuttle mechanism part.

Explanation of symbols

10 is a yoke, 11 is a magnet, 12 is a hammer shift plate, 13 is a timing belt, 14 is a coil, 15 is a coil shift plate, 16 is a bush, 17 is a guide shaft, 21 is a hammer bank, 30 is a platen, 31 is printing Paper, 32 is an ink ribbon, and 50 is a shuttle mechanism.

Claims (2)

A hammer bank in which a plurality of dot printing hammers are arranged and reciprocates in the digit direction, a magnet affixed to the yoke as a drive source for the hammer bank and linear motor, and the hammer bank reciprocate in opposite phases. In the dot line printer of the linear motor type shuttle mechanism supported by the bush and the coil shift plate that slide on the guide shaft,
The dot line printer, wherein the yoke and the coil are installed vertically so as to face each other, and the coil is connected to the coil shift plate installed above in a cantilever state. The cooling mechanism for generating the cooling air for cooling the coil is provided, and a cooling air passage for blowing the cooling air between the yoke and the coil is provided in the lower part of the coil. The dot line printer described.

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