JPH0316909B2 - - Google Patents

Description

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

Technical Background of the Invention and Problems There are conventional dot printers such as wire dot type and inkjet type. The wire dot method has the advantage of reliable printing. The disadvantage is that noise is generated due to the impact on the recording paper. The inkjet method has the advantage of not generating noise. The disadvantage is that the structure is complicated and manufacturing is difficult due to the requirement for precision.

Although each method has its advantages and disadvantages, ink dot printers that are designed to combine the features of these methods have recently been considered. Its structure is shown in FIGS. 1 to 3. A printing head 2 is provided which is movable along a platen (not shown) around which recording paper 1 is wound. This print head 2 is made up of a combination of a drive section 3, a guide section 4, and an ink supply section 5.

The drive section 3 has a case 6. A yoke 7 is housed within this case 6. A number of electromagnets 8 corresponding to the number of needles to be described later are attached to the yoke 7 in an annular manner. An armature 9 is provided opposite each of these electromagnets 8.

The guide section 4 has a guide case 10. A plurality of needles 11 are housed in this guide case 10. The tips of these needles 11 are arranged linearly in the vertical direction. These needles 11 are curved so as to open in an annular shape toward the rear. Each of the rear ends of these needles 11 is in contact with the movable end of the armature 9. These needles 11
A spring 12 is fitted in each of the needles 11 to urge each needle 11 in the return direction.

The ink supply section 5 includes an excitation coil 13, a pair of magnetic pole plates 14, an ink tank 15, and a tank holding plate 16. Specifically, the magnetic pole plate 14 is attached to the guide case 10. The excitation coil 13 is attached to the rear of the magnetic pole plate 14. A magnetic pole 17 is formed on the front part of such a magnetic pole plate 14 by bending the respective ends and facing each other.
As a result, the magnetic field slit 18 is formed vertically. The tip of the needle 11 is located in this magnetic field slit 18. The tips of these needles 11 are positioned in the same vertical plane. Further, the tank holding plate 16 is attached to the guide case 10. The ink tank 15 is detachably attached to the tank holding plate 16. Magnetic ink 19 is stored in this ink tank 15 . This ink tank 15 has an insertion hole 20 formed therein. The magnetic pole plate 14 is inserted into this insertion hole 20.
A downwardly extending connecting plate 21 integrally formed with each of the connecting plates 21 is inserted. Further, a card cartridge 22 storing the magnetic ink 19 is detachably attached to the ink tank 15 in a watertight manner.

Next, the operation of the ink dot printer having such a structure will be explained. First, excitation coil 1
When 3 is excited, the magnetic pole plate 14 is magnetized. As a result, the magnetic ink 19 from the ink tank 15 is attracted to the magnetic field slit 18, thereby forming a magnetic ink film 23 on the magnetic field slit 18 between the recording paper 1 and the needle 11. When the electromagnet 8 is excited in this state, the needle 11 flies and comes into contact with the recording paper 1. Since magnetic ink 19 is held in this needle 11, the magnetic ink 19 adheres to the recording paper 1 in the form of dots, and by repeating this operation, characters and figures are printed with low noise.

However, since the magnetic ink film 23 is formed against gravity, its thickness becomes thinner toward the top. Further, the tips of the needles 11 existing within the magnetic ink film 23 are located on the same vertical plane. Therefore, due to these, the distance between the tip of each needle 11 and the surface of the magnetic ink film 23 on the recording paper 1 side becomes smaller as the position increases, and the amount of magnetic ink 19 retained by the needle 11 increases as the position increases. As time goes by, the amount becomes smaller. As a result, shading occurs above and below the dots on the recording paper 1.

OBJECTS OF THE INVENTION The object of the present invention is to provide an ink dot printer that can make the density of dots formed by a needle uniform on the upper and lower sides.

SUMMARY OF THE INVENTION In this invention, the tips of the needles are positioned at equal distances from the recording section side surface of the magnetic ink film, so that the amount of magnetic ink held by each needle during printing is made uniform. By making the amount of magnetic ink that adheres to the recording area uniform for each dot,
The structure is such that the density on the top and bottom of the dot can be made uniform.

Embodiment of the Invention A first embodiment of the invention will be described based on FIG. The same reference numerals are used for the same parts as those described above, and the explanation is omitted (the same applies below). In this embodiment, the tips of the needles 24 are positioned at equal distances from the surface of the recording paper 1 side of the magnetic ink film 23 whose thickness decreases upward. That is, the needle 24
The tip is shifted backward as it goes upwards. Therefore, during printing, the amount of magnetic ink 19 held by the needle 24 is uniform regardless of whether it is upper or lower, so that the density of the upper or lower dots formed by the needle 24 is equalized.

Next, a second embodiment of the present invention will be explained based on FIGS. 5 to 7. Guide case 10
Shafts 25 that extend laterally are formed on both sides of the front portion. Magnetic pole plates 26 are rotatably attached to these shafts 25, respectively. The shaft 2 is located at the rear lower part of one of these magnetic pole plates 26.
A track-shaped long hole 27 is formed along the radial direction of the hole 5 . A cam 29 having a knob 28 is inserted into the elongated hole 27 . This cam 29 is attached to the guide case 10 with screws 30. Further, the magnetic pole 31 is formed such that the length of the magnetic path from the excitation coil 13 becomes shorter as it goes upward. Such a magnetic pole 31 is formed so as to be inclined rearward and downward so that the surface on the side of the recording paper 1 becomes a vertical plane when the magnetic ink film 23 is formed.

In such a configuration, when the excitation coil 13 is excited, a magnetic ink film 23 is formed on the magnetic field slit 18, but the length of the excitation from the excitation coil 13 becomes shorter as the magnetic pole 31 moves upward. A formed magnetic field gradient is provided and
Since the magnetic pole 31 is formed so as to be inclined backwardly and downwardly, the surface of the magnetic ink film 23 on the recording paper 1 side becomes a vertical surface. Since the tips of the needles 11 existing in the magnetic ink film 23 in this state are located on the same vertical plane, the tips of each needle 11 are located at equal distances from the surface of the recording paper 1 in the magnetic ink film 23. located in position. Therefore, the amount of magnetic ink 19 held by each needle 11 during printing is made uniform, and the density of the upper and lower dots formed by the needles 11 is made uniform.

If the density of the magnetic ink 19 changes due to an external cause such as a rise in temperature and the surface of the magnetic ink film 23 on the recording paper 1 side cannot be maintained in a vertical plane, the cam 29 is rotated by the knob 28. Then, the magnetic pole plate 26 rotates about the shaft 25, and the magnetic pole 31
The inclination angle is adjusted so that the surface of the magnetic ink film 23 on the recording paper 1 side is a vertical plane.

In this embodiment, the surface of the magnetic ink film 23 on the side of the recording paper 1 was not formed to be a vertical surface only by the magnetic field gradient due to the length of the magnetic path, but the difference could be made by changing the length of the magnetic path. If materials with different magnetic permeabilities are used, etc., it is possible to make the surface of the magnetic ink 23 on the recording paper 1 side perpendicular even by the magnetic field gradient.

Effects of the Invention As described above, in this invention, the tip of each needle is positioned at the same distance from the surface of the recording section side in the magnetic ink film, so the amount of magnetic ink retained by each needle during printing is This makes it possible to make the density of the dots formed by the needle uniform on the top and bottom, and also to make the magnetic field gradient so that the surface of the magnetic ink film on the recording section side becomes a vertical plane. Since the tip of each needle is positioned at the same distance from the surface of the magnetic ink film on the recording section side, the amount of magnetic ink retained by each needle during printing can be made uniform.
This makes it possible to equalize the density above and below the dots formed by the needle.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an ink dot printer;
FIG. 2 is a partially cutaway side view, FIG. 3 is a partially enlarged side view, FIG. 4 is a side view of the first embodiment of the invention, and FIG. 6 is a plan view showing a second embodiment of the present invention, FIG. 6 is a side view thereof, and FIG. 7 is a side view showing the state when the magnetic ink film is formed. 1... Recording paper (recording section), 3... Drive section, 11
...Needle, 14...Magnetic pole plate, 17...Magnetic pole,
18...Magnetic field slit, 19...Magnetic ink, 2
4... Needle, 26... Magnetic pole plate, 31... Magnetic pole.

Claims (1)

[Claims] 1. A magnetic field slit in which a magnetic ink film made of magnetic ink is formed is formed in the vertical direction by opposing the magnetic poles of a pair of magnetic pole plates, and is selectively driven by a driving section. A plurality of needles that move toward the recording section are arranged along the magnetic field slit, and each tip of the needle is positioned at a position equidistant from the surface of the magnetic ink film on the recording section side. An ink dot printer characterized in that it is provided with an ink dot printer. 2. A magnetic ink film made of magnetic ink is formed by making the magnetic poles of a pair of magnetic pole plates face each other. A magnetic field slit is formed in the vertical direction, and a recording section is provided to face the magnetic ink film, and a recording part is provided to face the magnetic ink film. A magnetic field gradient is provided so that the surface of the magnetic ink film on the side of the recording section is a vertical plane, and a plurality of needles that are selectively driven by a driving section and move toward the recording section are moved through the magnetic field slit. An ink dot printer characterized in that the needles are arranged along the magnetic ink film, and each tip of the needle is positioned at a position equidistant from the surface of the magnetic ink film on the side of the recording section.