JPS61112655A - Ink dot printer - Google Patents

Abstract

PURPOSE:To prevent the occurrence of spark as well as keep good-quality printing by a method in which a smooth surface with small roughness is provided for the needle side face of an electrode in such a way as to eliminate the local concentration of electric field on the surface of the electrode and also to generate even electric field between the needle and the electrode. CONSTITUTION:An electrode 47 set in parallel with the scanning direction of a printing head 13 in the face of the head 13 is held on an electrode holder 48. The electrode 47 made of steel has a surface roughness of 25mum or less for its needle 24 side face, having a smoothly finished planar surface 47a. Since the surface 47a of the electrode 47 is of a roughness of 25mum or less, no local concentration of electric field between the electrode 47 and the needle 24 takes place. The occurrence of spark can thus be prevented, and the flying direction of ink 43 can be stabilized. The quality of printing can thus be raised.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ink dot printer that forms characters and figures with a collection of dots formed by ink.

Conventional Technology Generally, in this type of ink dot printer, ink is deposited on the tip of a needle that is selectively driven by a drive unit to reciprocate, and the tip of the needle collides with the surface of recording paper to form a dot. I'm letting you do it. That is, the eighth
As shown in the figure, a magnetic ink is used as the ink 1, an ink film 3 is formed by magnetic poles 2 spaced apart at a predetermined interval, and the tip 5 of the needle 4 is positioned within this ink film 3. . A recording paper 6 is placed opposite the tip 5 of the needle 4. The position of the tip 5 of this needle 4 is set so that there is a slight distance between it and the film surface 7 on the recording paper 6 side in the rest position shown in FIG. 8a. Then, the needle 4 is driven by a drive unit (not shown) and moves with the ink 1 attached to the tip 5 as shown in FIG. 8C. is brought into contact with the recording paper 6, and the ink 1 is brought into contact with the recording paper 6 to form dots.

Thus, the amount of ink 1 used to form the dots varies depending on the position of the tip 5 of the needle 4 within the ink film 3. That is, if the tip 5 protrudes toward the recording paper 6 side from the film surface 7, the amount of ink will be insufficient, and if the tip 5 is located in a direction away from the recording paper 6, even if the amount of ink increases, ink droplets will scatter. Therefore, good dots cannot be formed.

However, the type 2 dot printer has the disadvantage that the needle 4 collides with the recording paper 6, which generates a large amount of noise. For this reason, a non-contact type ink dot printer has been proposed in which the needle does not come into contact with the recording paper. In this case, the principle of dot formation is that a needle is provided so that it can reciprocate so that its tip does not come into contact with the recording paper, and an electrode is faced to the needle, and an electric field is created between the needle and the electrode. Apply.

The strength of the electric field is such that it has no effect on the stationary needle and causes the ink at the tip of the nearby needle to electrostatically fly toward the recording paper.

Another type of printer is to fix multiple needles and selectively apply sufficient voltage to cause ink to fly between the needles and the electrodes at the timing required for printing. There are some things.

Problems to be Solved by the Invention Both types use flat electrodes as electrodes, but if the surface of the needle is rough, a locally concentrated electric field is generated, and the electric field is uniform over the entire surface. This makes it impossible to obtain a suitable electric field, causing disturbances in the flight of ink, degrading print quality, and easily generating sparks.

Means for Solving the Problem The surface of the electrode 47 on the needle 24 side is made into a smooth flat surface 47a with small roughness.

Since the surface of the electrode 47 that the tip 34 of the working needle 24 faces is a smooth flat surface 47a with little roughness, even if a voltage is applied between the two to generate an electric field, a local electric field will not occur on the surface of the electrode 47. There is no concentration, which causes the needle 24 and electrode 4 to
A uniform electric field is generated between the print head and the print head 7 to maintain good printing quality, and no sparks are generated.

Embodiment First, inside the printer main body 8, a carrier shaft 9 and a guide shaft 10 are provided in parallel.

A carrier 11 is attached to these carrier shaft 9 and guide shaft 10 so as to be able to reciprocate. This carrier 11 has a print head 1 facing the recording paper 12.
3 is installed.

The print head 13 has a head mounting portion 15 having a mounting hole 14, and a head cover 16 is attached to the head mounting portion 15. This head cover 16 is made of a synthetic resin material, and a drive section 17 is attached to the circular portion at the rear. That is, the magnetic member 18 formed of a magnetic material and joined to the stepped portion of the head cover 16 has a flat partition wall 19, and the partition wall 19 has a plurality of cores 21 around which the coil 20 is wound.
are arranged on the same circumference, and a yoke 22 is formed on the outer periphery of each of these cores 21. The coil 20
The voltage applied to the coil 20 is 12 to 13 V based on the print signal.The yoke 22 has a rotatable base of an armature 23 facing each of the cores 21. Needles 24 are fixed to the tips of these armatures 23. These needles 24 consist of, for example, nine needles, the material of which is stainless steel, and the diameter of which is 0.2.
It is mm. A needle spring 25 is provided between the partition wall 19 of the drive section 17 and the armature 23.
is provided, and the needle 24 and the armature 23 are urged rearward by the needle spring 25. The needles 24 pass through through holes 26 formed in an annular arrangement in the partition wall i9, and are guided by an intermediate guide 27 and a tip guide 28 to penetrate the ink film forming means 29. The ink film forming means 29 includes magnetic poles 3o facing each other and a slit 31 formed by these magnetic poles 3o, and an ink film 32 is formed within the slit 31. The magnetic pole 30 extends upward along both sides of the head cover 16, and
A magnet 33 located on the top of the head cover 16
is connected to. The tip 34 of the needle 24 is formed into a spherical shape, and the end of the tip 34 is positioned so as to be in contact with the film surface 35 of the ink film 32 on the recording paper 12 side.

The positions of such a plurality of needles 24 are determined by the tip guide 28 so that their tip portions are arranged close to each other in the vertical direction. Furthermore, a rear cover 36 is provided at the rear of the head cover 16.
The rear cover 36 is provided with a presser spring 37 that applies force in the return direction to the armature 23 and a stopper 38 that determines the return position of the armature 23. Further, a PWFi 40 having a connector 39 and forming an electric circuit for controlling energization to the coil 20 is attached to the head cable 16.

Further, an ink tank 41 made of synthetic resin is attached below the tip of the head cover 16. This ink tank 41 is provided with an ink impregnating material 42 and stores ink 43 therein, and a lower protrusion 45 of the magnetic pole 30 is inserted into a hole 44 formed on the upper surface.

This ink 43 is magnetic ink. Further, an ink cassette 46 containing a certain amount of ink 43 is detachably attached to the upper surface of the ink tank 41.

Next, an electrode #47 is provided facing the print head 13 and disposed parallel to the scanning direction of the print head 13 and held by an electrode holder 48. This electrode 47
is made of copper, and its surface on the needle 24 side has a roughness of 25 μm or less and is a flat surface 47a that is finished smoothly. Although not particularly shown, both ends of the electrode 47 are held with an insulating material.
and is supported by the side plate. A pair of paper presser guide rollers 49 are provided above and below this electrode 47 to tightly bond the recording paper 12 to the electrode 47, and further above and below these paper presser guide rollers 49 are paper feed rollers 50. and a paper tension roller 51 are disposed, the paper feed roller 50 is provided with a paper feed press roller 52 in a pair, and the paper tension roller 51 is provided with a paper press roller 53 in a pair. There is. Therefore, a constant electric field is applied between the needle 24 and the electrode 47 by the power supply section 54. The strength of this electric field is such that the tip portion 34 of the needle 24 is in a stationary state.
without causing the ink 43 to fly from the recording paper 1.
The setting is such that the ink 43 can be sucked from the tip 34 of the needle 24 close to the second side and made to fly.

In such a configuration, the print head 13 reciprocates and is given a print signal in response to the movement; however, by energizing the magnet 33, the ink 43 is pulled up into the slit 31 between the magnetic poles 30 and the ink film 32 The needle 24 that is to form dots projects toward the recording paper 12 side. At this time, the tip 34 of the needle 24 does not come into contact with the recording paper 12, but since an electric field is applied by the power source 54, the needle 24 near the electrode 47
The ink 713 adhering to the tip 34 of the recording paper 12 flies toward the electrode 47 due to the force of the electric field and forms a dot on the surface of the recording paper 12. In this case, since the end of the tip 34 of the needle 24 on the recording paper 12 side is in contact with the film surface 35 of the ink film 32 when it is stationary, no waves are generated on the film surface 35. Therefore, even if the two needles 24 operate at the same time, the ink between the needles 24 will not spill out. Further, the amount of ink 43 adhering to the tip 34 of the needle 24 is also constant, resulting in stable printing quality.

Therefore, the roughness of the flat surface 47a of the electrode 47 is 25 μm.
Therefore, no local concentration of electric field occurs between the needle 24 and the needle 24. Therefore, no sparks are generated, the flying direction of the ink 43 is also stable, and printing quality is improved.

In the above embodiment, the needle 24 is connected to the electrode 47.
Although the needles 24 are of the type that move forward and backward toward the target, these needles 24 are fixed.

The same applies to a type in which the ink 43 is selectively ejected by applying a voltage to each separately.

Effects of the Invention The present invention generates an electric field for causing ink to fly between a needle having ink attached to its tip and an electrode facing the needle, as described above, in which the needle side of the electrode Since the surface is a smooth flat surface with little roughness, there is no local electric field concentration on the electrode surface, which eliminates the generation of sparks due to dielectric breakdown and improves printing quality by stabilizing the flying state of the ink. It is something that can be done.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of a print head showing an embodiment of the present invention, FIG. 2 is a partially cutaway perspective view of the entire printer,
Figure 3 is a perspective view of the print head, Figure 4 is a rear view of the print head with the rear cover and armature removed;
Fig. 5 is a perspective view of the electrode part, Fig. 6 is a cross-sectional view for explaining the ink flying state, Fig. 7 is a partial cross-sectional view showing the relationship between the needle and the electrode, and Fig. 8 is a conventional example. FIG. 12・Recording paper, 24... Needle, 34・Tip part,
43...Ink, 47...Electrode, 47a...Plane ratio Request person Tokyo Electric Co., Ltd. drawing, 71 level (Contents: No changes) Around a-! i41 JLL Figure 36 Figure 35 (W'') Z Procedural Amendments (W) March 28, 1985 Mr. Manabu Shiga, Commissioner of the Patent Office■, Indication of Case Patent Application No. 59-233949 2, Name of Invention Ink Dot Printer 3. Relationship with the case of the person making the amendment Patent applicant 4. Agent 107 Address 5-9-15 Minami-Aoyama, Minato-ku, Tokyo 1985 2
Month 26th (shipment date) 6. Drawings subject to amendment 7. Contents of amendment

Claims (1)

[Claims] 1. It has a plurality of needles with ink attached to their tips facing the recording paper, and electrodes facing the tips of these needles, and between the electrodes and the needles. An ink dot printer that applies an electric field strong enough to cause the ink to fly toward the recording paper, characterized in that a surface of the electrode on the needle side is a smooth flat surface with small surface roughness. dot printer. 2. The ink dot printer according to claim 1, wherein the electrodes are arranged parallel to the scanning direction of the print head.