JPH0318590B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a dot printer using magnetic ink.

Technical background of the invention and its problems Conventionally, in a dot printer that prints by selectively driving a plurality of needles, a print head is mounted on a carriage that moves along recording paper wound around a platen. An ink film forming body that forms an ink film made of magnetic ink is attached to the head, and this ink film is formed between the tip of the needle of the printing head and the recording paper, and the tip of the needle is brought into contact with the recording paper to It has been proposed that magnetic ink adhered to the recording paper be deposited in the form of dots, and characters are formed by aggregation of these dots so that printing can be performed with low noise.

The ink film forming body consists of an electromagnetic coil and a pair of ink film forming plates connected to the electromagnetic coil, and these ink film forming plates each have different magnetic poles located at their edges facing each other to create a magnetic field slit. is forming. When magnetic ink is supplied to this magnetic field slit, an ink film is formed, and an ink tank is considered as a means for supplying magnetic ink to this magnetic field slit. First, it has been considered that the ink tank is located above the ink film forming plate and these are combined. The advantage of this is that magnetic ink can be supplied well even when the magnetic force is weak, but the disadvantage is that when the excitation is removed, the magnetic ink present in the magnetic field slit is discarded, resulting in a large consumption amount. Therefore, it has been considered that the ink tank is located below the ink film forming plate and these are combined. The advantage of this is that the magnetic ink can be recovered and its consumption is small, but the disadvantage is that the magnetic force must be strengthened to supply the magnetic ink.

Further, since it is desired that this ink tank has a large ink storage capacity, it is considered that the ink tank is formed to have a long shape in the direction of movement of the carriage. However, in such a device, when the carriage starts and stops moving, the magnetic ink in the ink tank shifts to one side, which causes a large change in the liquid level of the magnetic ink and changes the state of supply of the magnetic ink to the magnetic field slit. As a result, the thickness of the ink film increases or decreases, and the amount of magnetic ink that adheres to the tip of the needle increases or decreases, which in turn increases or decreases the amount of magnetic ink that adheres to the recording paper, resulting in variations in the density of each dot. This occurs and good printing cannot be performed.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a dot printer that can print with uniform density by reducing changes in the liquid level due to deviation of magnetic ink.

Summary of the Invention This invention provides a partition plate with a through hole formed inside an ink tank along a direction perpendicular to the direction of movement, thereby reducing changes in liquid level due to unevenness of ink, thereby reducing the magnetic field. The structure is such that the amount of magnetic ink supplied to the slit, the thickness of the ink film, and the amount of magnetic ink adhered to the slit are made uniform, thereby making it possible to print with uniform density.

Embodiment of the Invention An embodiment of the invention will be described based on the drawings. First, a platen 2 is installed horizontally in the housing 1 with its axis oriented in the left-right direction, and a carriage shaft 3 and a guide shaft 4 are installed parallel to the platen 2.
is provided. A carriage 5 is slidably attached to the carriage shaft 3 and the guide shaft 4. This carriage 5
is connected to a known carriage moving device (not shown) comprising a pulley, a wire wound around the pulley, and a motor connected to some of the pulleys.

A print head 6 is mounted on the carriage 5. A case 7 of the print head 6 is provided with an armature guide 8 and a yoke 9. A large number of armatures 10 are housed inside the armature guide 8 in a radial manner with their movable ends directed toward the center. In the yoke 9, a large number of electromagnets 11 serving as a driving section are arranged in an annular shape facing the armature 10. Also,
In the case 7, a petal-shaped leaf spring 12 and a stopper 13 are housed, which press the rear end of the armature 10 to urge the armature 10 away from the electromagnet 11. The stopper 13 is in contact with the tip of the armature 10, which is biased by the leaf spring 12. A PC board 14 for connecting an external circuit (not shown) and the electromagnet 11 and a guide frame 15 are attached to the front part of the case 7. A number of needles 16 corresponding to the number of armatures 10 are housed in the guide frame 15 so as to be movable toward the platen 2. The tips of these needles 16 are arranged in a straight line in the vertical direction, and the rear ends of these needles 16 are located inside the case 7 and are arranged in an annular shape facing the armature 10. These needles 16
A needle cap 17 is attached to the rear end of the
These needle caps 17 are connected to the needle 1
A spring 18 attached to the needle 16 is engaged, so that the needle cap 17 of the needle 16, which is biased rearward, is brought into contact with the armature 10. Further, an ink film forming body 19 is attached to the guide frame 15. The ink film forming body 19 consists of an electromagnetic coil 20 connected to an external circuit and a pair of ink film forming plates 21 attached to both ends of the electromagnetic coil 20. A connecting plate 22 extending downward is integrally formed at the tip, and a bent piece 23 is formed at the tip of the ink film forming plate 21 by bending it parallel to the platen 2. A magnetic field slit 25 is formed in each of these bent pieces 23 by making the respective magnetic poles 24 face each other with a gap between them. The tip of the needle 16 is located within this magnetic field slit 25. An ink film 27 made of magnetic ink 26 is formed on this magnetic field slit 25 .

Next, a tank mounting base 27a is attached to the guide frame 15. A rectangular parallelepiped-shaped ink tank 28 with a longer dimension in the left-right direction is attached to the tank mounting base 27a. This ink tank 28 has a fitting tube 29 whose tip is formed obliquely on the left side of the upper surface plate, and an inlet 3 that communicates with the fitting tube 29 and projects into the ink tank 28.
0 is formed. A cylindrical cartridge 31 is removably fitted into the fitting tube 29 in a watertight manner at its lower end opening. Further, an air hole 32 is formed on the top plate of the ink tank 28 near the inlet port 30, and an insertion hole 33 is formed slightly to the right side of the top plate along the left-right direction. The connecting plates 22 are inserted into each of the insertion holes 33, so that a passage hole 34 is formed in the insertion hole 33. Next, a through hole 35 which also serves as an air hole is formed in the upper surface plate of the ink tank 28 so as to be connected to the passage hole 34 .

Two partition plates 36 serving as partition plates are housed within the ink tank 28. These partition plates 36 are housed with the connection plate 22 in between, so that the distance between them is as small as possible, and they are housed along the front-rear direction, which is a direction perpendicular to the direction of movement of the carriage 5. A through hole 37, 38 is provided at the top and bottom of these partition plates 36, respectively.
is formed. The lower edge of the upper through hole 37 is formed to match the level of the liquid level when the magnetic ink 26 sways when the carriage 5 moves. The magnetic ink 25 flows through the through hole 38 .

In such a configuration, since the partition plate 36 is housed in the ink tank 28 along a direction perpendicular to the moving direction of the carriage 5, changes in the liquid level due to deviation of the magnetic ink 26 that occurs when the carriage 5 moves becomes smaller. In particular, changes in the liquid level around the connecting plate 22 are smaller because the partition plates 36 are housed with the connecting plate 22 in between to minimize the distance between them.

In this way, since the change in the liquid level of the magnetic ink 26 in the ink tank 28 becomes small, on the one hand, from the air hole 32, that is, in the ink tank 28
The magnetic ink 26 will not spill out. On the other hand, the amount of magnetic ink 26 supplied to the magnetic field slit 25, the thickness of the ink film 27, and the needle 1
The amount of the magnetic ink 26 attached to the recording paper 6 and the amount of the magnetic ink 26 attached to the recording paper (not shown) serving as the recording section are uniform, and printing with uniform density can be performed.

In addition, in this embodiment, the partition plate 36 is used as the partition plate.
However, the ink tank 28 may be formed of a water-permeable material, or ribs may be formed on the ink tank 28 to serve as a partition plate. Next, the through holes 37 and 38 of the partition plate 36 may be formed into a circular or semicircular shape as shown in FIG. 7, and the number thereof may be plural. In addition, the magnetic ink 26 from the air holes 32 etc.
In order to prevent the ink from spilling, the walls around the air holes 32 and the like may be extended upward so that the upper edges of the air holes 32 and the like are located above the top surface of the ink tank 28 .

Effects of the Invention Since the present invention is constructed as described above, it is possible to reduce the change in the liquid level of the magnetic ink. The amount can be made uniform, which has the effect that even if an ink tank with a large storage capacity is used, it is possible to print with uniform density.

[Brief explanation of the drawing]

FIG. 1 is an overall perspective view showing one embodiment of the present invention, FIG. 2 is a perspective view of its print head, FIG. 3 is a side view showing a partially cut away portion of the print head, and FIG. 4 is a perspective view of the print head. A plan view of the printing head, FIG. 5 is a longitudinal side view of the ink tank, and FIGS. 6a and b are longitudinal front views showing the state when the carriage is moved.
FIG. 7 is a longitudinal sectional side view showing a modification of the partition plate. 5...Carriage, 16...Needle, 21...
...Ink film forming plate, 26...Magnetic ink, 28...
... Ink tank, 32 ... Air hole, 33 ... Insertion hole, 36 ... Partition plate (partition part), 37-38 ...
Through hole.

Claims (1)

[Claims] 1. An ink tank whose shape is elongated in the direction of movement is provided on the carriage that moves along the recording section, and the upper surface plate of this ink tank has an insertion hole into which the lower part of the ink film forming plate for adhering magnetic ink to the needle is inserted, and the interior thereof. an air hole for supplying air to the ink tank, and two partition plates are arranged in a direction perpendicular to the direction of movement of the ink film forming plate inserted in the ink tank, sandwiching the ink film forming plate inserted into the ink tank; A dot printer characterized in that through holes are formed on the upper and lower sides of these partition plates, respectively, and the lower edge of the upper through hole is made to match the height of the liquid level of magnetic ink during rocking.