JPS61104863A - Ink dot printer - Google Patents

Abstract

PURPOSE:To make possible a stable dot formation to be carried out by providing a surface potential maintaining means which maintains the surface potential constant in a non-contacting ink dot printer. CONSTITUTION:An electrode 47 is provided being held by an electrode holder 48 made of insulation material having a small contacting resistance such as a plastics opposite to a printing head 13. A press down plates 49 are provided as a surface potential maintaining means contacting with a recording paper 12 to the surface of the electrode holder 48 closely, at the upper and lower portions disposed on a side directed to the printing head of a surface of this electrode 47. The recording paper 12 is supplied together with an advancement of a printing operation, an electric charge of the printing paper 12 is in free condition, and the surface potential thereof is constant, since it is contacted to the electrode 47 by the press down plates closely.

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 first
As shown in Figure 5, a magnetic ink is used as the ink 1, an ink film 3 is formed by magnetic poles 2 spaced apart at a predetermined distance, and the tip 5 of the needle 4 is positioned within this ink film 3. There is. 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 side of the recording paper 6 in the static position shown in FIG. 15a. and.

The needle 4 is driven by a drive unit (not shown),
As shown in FIG. 15, ink 1 is applied to the tip 5 of the needle 4 and the needle is moved, and as shown in FIG. The dots are formed by contacting the 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, this type of 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. The electric field is applied so that the electric field has no effect on the stationary needle, and the ink at the tip of the needle that is close to the recording paper is electrostatically ejected.

Problems to be solved by the invention In such a non-contact type ink dot printer,
The flying state of the needle changes depending on the strength of the electric field between the needle and the electrode. However, what actually determines the flight state is the electric field strength between the needle and the surface of the recording paper. The surface potential of this recording paper changes significantly depending on whether or not the recording paper is in close contact with the electrodes. That is, if the recording paper is not in close contact with the electrodes, the movement of charges on the surface of the recording paper will be hindered, and the surface potential of the recording paper will not rise sufficiently.

In addition, the ink flying from the needle is charged because it is in an electric field, but when the ink reaches the recording paper, the polar charge force that was charged on the ink accumulates on the surface of the recording paper, and the needle The Coulomb force with the side weakens,
Ink becomes difficult to fly.

Means for Solving the Problem One or more needles 24 and the needles 24 are reciprocated toward the recording paper 12 by a drive unit 17 with ink 43 attached to the tip end 34 facing the recording paper 12.
The ink 43 is directed toward the recording paper 12 from the tip 34 of the needle 24 close to the recording paper 12 between the electrode 47 and the needle 24. In an ink dot printer that applies an electric field strong enough to cause the ink to fly, the surface potential maintaining means 49 brings the recording paper 12 into close contact with the electrode 47 to maintain its surface potential constant.

During the printing operation, the recording paper 12 is brought into close contact with the electrode 47 by the surface potential maintaining means 49, so that the charge on the surface of the recording paper 12 can move freely, so that it is not regulated by the voltage of the electrode 47. The surface potential of the electrode 47 is maintained, and even if charged ink 43 adheres, the charge is transferred to the electrode 47.
The surface potential of the recording paper 12 is maintained constant by moving the recording paper 12 to the side.

Embodiment First, a first embodiment of the present invention will be described based on FIGS. 1 to 10. A carrier shaft 9 and a guide shaft 10 are provided in parallel inside the printer main body 8.
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 13V, although the current supply to the coil 20 is based on a print signal. The bases of armatures 23 facing the cores 21 are rotatably attached to these yokes 22, and needles 24 are fixed to the tips of these armatures 23. These needles 24 are made of, for example, nine needles, made of stainless steel, and have a diameter of 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 annularly arranged through holes 26 formed in the partition wall 19, and are guided by an intermediate guide 27 and a tip guide 28 to penetrate the ink film forming means 29. This ink film forming means 29 consists of opposing magnetic poles 30 and a slit 31 formed by these magnetic poles 3o, and an ink film 32 is formed within this 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
I'm connected to it. 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 distal end guide 28 so that the distal end portions of the plurality of needles 24 are arranged close to each other in the vertical direction. Further, a rear cover 36 is attached to the rear part of the head cover 16, and the rear cover 36 is provided with a presser spring 37 that applies force in the direction of returning the armature 23, and a stopper 38 that determines the return position of the armature 23. I'm here. Further, a PW board 40 is attached to the head cover 16 and has a connector 39 and is formed with an electric circuit for controlling energization to the coil 20 .

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 held by an electrode holder 48 made of an insulating material with low contact friction, such as synthetic resin. That is, it is embedded in the center of the electrode holder 48. This electrode 47 is made of copper, and an insulating film made of polyimide resin is formed on the contact surface with the recording paper 12. Further, although not particularly shown, both ends of the electrode 47 are held by an insulating material and supported by a side plate.

Pressing plates 49 as surface potential maintaining means for keeping the recording paper 12 in close contact with the surface of the electrode holder 48 are provided above and below the surface of the electrode 47 on the print head 13 side. A paper feed roller 5o and a paper tension roller 51 are disposed, and the paper feed roller 50
A paper feed press roller 52 is provided in a pair on the paper tension roller 51, and a paper press roller 53 is provided in a pair on the paper tension roller 51. 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 ink 43 does not fly from the tip 34 of the needle 24 in a stationary state, and the ink 43 does not fly from the tip 34 of the needle 24 close to the recording paper 12. It is set to such an extent that it can be sucked in and sent flying.

In such a configuration, the print head 13 reciprocates and is given a print signal in response to the movement; however, when the magnet 33 is energized, 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 43 adhering to the tip 34 flies toward the electrode 47 due to the force of the electric field, forming 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 of the ink film 32. Therefore, even if two needles 24 operate at the same time, the ink between the needles 24 will not splash out, and the amount of ink 43 adhering to the tip 34 of the needle 24 is also constant, resulting in stable printing quality. becomes.

As the printing operation progresses, the recording paper 12 is fed, but since it is kept in close contact with the electrode 47 by the presser plate 49,
The charge on the recording paper 12 is in a free state, and its surface potential is constant. In particular, even if the charged ink 43 flying from the needle 24 adheres to the recording paper 12, the charge is neutralized by the voltage of the electrode 47 and does not change the surface potential.

Next, the holding plate 49 shown in FIG. 7 has an inclined edge on one side, and the holding plate 49 shown in FIG. 8 has an arcuate edge between the holding plate 49 and the electrode holder 48. It is being formed. Further, the presser plate 49 shown in FIG. 9 has one side edge curved, and the presser plate 49 shown in FIG.
is bent to the side of the electrode holder 48.

Next, a second embodiment of the present invention will be described based on FIGS. 11 and 12. The same parts as in the previous embodiment are designated by the same reference numerals, and the description thereof will be omitted. In this embodiment, a presser plate 49 is attached to the print head 13 side, and is formed of an elastic thin plate into an oval shape.
It is fixed at

Furthermore, the square shown in FIG. 13 is a third embodiment of the present invention, in which through holes 55 as negative pressure means are formed in the upper and lower parts of the electrode holder 48 that holds the electrode 47, and these through holes are A negative pressure generating means 56 is connected to 55.

Therefore, the recording paper 12 is always subjected to negative pressure at the through hole 55 portion and comes into close contact with the electrode 47. As a result, the recording paper 12
The surface potential of is maintained constant.

Moreover, what is shown in FIG. 14 is a fourth embodiment of the present invention, in which another electrode plate 57 is placed above and below the electrode 47 and embedded in the electrode holder 48 to serve as a surface potential maintaining means. It is something. That is, this electrode plate 57 is an electric field generating means and is connected to a power supply circuit (not shown) to generate the recording paper 1.
2 is electrostatically attracted to the electrode 47 side.

Effects of the Invention As described above, the present invention provides one or more needles that are reciprocated toward the recording paper by a drive unit, with ink attached to the tip facing the recording paper, and the tip of the needle. In an ink dot printer, an electric field is applied between the electrode and the needle with a strength that causes the ink to fly toward the recording paper from the tip of the needle close to the recording paper. Since a surface potential maintenance means is provided to keep the surface potential of the recording paper constant by bringing the paper in close contact with the electrode, the recording paper does not become detached from the electrode and its surface potential changes. The flying of ink is compensated for, and even if charged ink adheres to the recording paper, there is no effect, and stable dot formation can be achieved.

[Brief explanation of the drawing]

FIG. 1 shows a first embodiment of the present invention, and is a longitudinal sectional side view of a print head, FIG. 2 is a partially cutaway perspective view of the printer, FIG. 3 is a perspective view of the print head, and FIG. The figure is a rear view of the print head with the rear cover and armature removed, Figure 5 is a perspective view of the electrode section, Figure 6 is an enlarged sectional view of the tip of the needle, and Figures 7 to 10 are the presser foot. FIG. 11 is a perspective view of a portion of a modified example of the plate, FIG. 11 is a perspective view of a print head showing a second embodiment of the invention, FIG. FIG. 14 shows a partial vertical side view of the fourth embodiment of the present invention, and FIG. 15 shows a partial vertical side view of a conventional example. FIG. DESCRIPTION OF SYMBOLS 12... Recording paper, 17... Drive unit, 24... Needle, 34... Tip part, 43... Ink, 47...
- Electrode, 49... Pressing plate (surface potential maintenance means), 55
...Through hole (negative pressure generating means), 57...Electrode plate (electric field generating means) Applicant: Tokyo Electric Co., Ltd. Engraving on page 1 (no change in content) 3. Amendment document filed March 28, 1985 1, Indication of the case Japanese Patent Application No. 59-225532 2, Name of the invention Ink dot printer 3, Person making the amendment Relationship with the case Patent applicant 4, Agent Address: 107 Address 5-9-15 Minami Aoyama, Minato-ku, Tokyo 1985 2
Month 26th (shipment date) 6. Subject to correction

Claims (1)

[Scope of Claims] 1. One or more needles whose tips facing recording paper have ink adhered to them and are reciprocated toward the recording paper by a drive unit, and electrodes facing the tips of the needles. In an ink dot printer, an electric field is applied between the electrode and the needle with a strength that causes the ink to fly toward the recording paper from the tip of the needle close to the recording paper. An ink dot printer characterized in that a surface potential maintaining means is provided for maintaining a constant surface potential of the recording paper by bringing the recording paper in close contact with the electrode. 2. The ink dot printer according to claim 1, wherein the surface potential maintaining means is a presser plate. 3. The ink dot printer according to claim 1, wherein the surface potential maintaining means is a negative pressure means that acts on the recording paper. 4. The ink dot printer according to claim 1, wherein the surface potential maintaining means is an electric field generating means acting on the recording paper.