JPH0418550B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a printing apparatus that forms an image by selectively ejecting ink droplets using electrostatic means.

Prior Art Conventionally, ink dot printers that form images by ejecting ink droplets from nozzles have had a fatal defect in that the nozzles become clogged.

Therefore, in order to prevent ink clogging, there are conventional devices in which an image is formed by ejecting ink held in a slit instead of a nozzle. As an example of such a thing, as shown in FIG.
There is one described in Publication No. 42664.
That is, a large number of recording electrodes 2 are arranged within a slit 1 that holds ink, and a counter electrode 4 is arranged to face these recording electrodes 2 with a recording paper 3 interposed therebetween. A power source 6 is connected between the recording electrode 2 and the counter electrode 4, with a switching element 5 interposed between each electrode to generate a potential difference sufficient to cause ink to fly between the two. ing.

With such a configuration, when the switching element 5 is selectively turned on in response to a print signal, a potential difference is generated between each recording electrode 2. Then, the ink in the portion where the voltage is applied flies toward the counter electrode 4, thereby performing printing. At this time, since the ink is held within the slit 1, clogging of the ink is prevented.

Problems to be Solved by the Invention However, in the above-described structure in which the ink is held within the slit 1, the structure for releasing the ink droplets from the slit 1 is delicate.
Lacks stability. For this reason, it is difficult to always form dots at a fixed location, resulting in the disadvantage that stable printing cannot be performed.
In addition, in order to stabilize the flying state of ink even a little, it is necessary to place the slit 1 close to the recording paper 3. In this case, the ink in the slit 1 comes into contact with the recording paper 3 more easily, causing the recording paper 3 to It also has the disadvantage of getting dirty.

On the other hand, using magnetic ink,
A device in which this is magnetically held at the tip of a needle-shaped recording electrode is being considered. In this type of device, the electric field tends to concentrate at the tip of the needle-shaped recording electrode, and the recording electrode and the recording paper can be placed with some distance from each other, so there is no possibility of accidents that could stain the recording paper. few. However, since magnetic ink is a liquid containing iron oxide powder,
It has a ground color and has little freedom of coloring, making it unsuitable as an ink for color printing.

The present invention has been made in view of the above points, and an object of the present invention is to provide a printing device that can perform stable printing without staining recording paper.

Means for Solving the Problems The present invention forms a recording electrode in a member or shape that does not have an impregnating property, and also forms the tip of the recording electrode in a tapered shape. A holding hole with a rough inner peripheral surface was provided, and the tip of the recording electrode was held in this holding hole.

Function: The tip of the recording electrode is supplied with ink that has flowed between the recording electrode and the inner peripheral surface of the holding hole. Therefore, when a certain electric field is generated between the recording electrode and the counter electrode, the electric field is concentrated at the tip of the tapered recording electrode, and the ink supplied to that part is well-flyed. Therefore, printing can be performed without bringing the recording electrode close to the recording medium, and staining of the recording medium due to contact with the recording electrode is prevented. Furthermore, since the recording electrode is reliably positioned within the holding hole, the direction of ink flight is constant.
This ensures stable printing.

Embodiment of the Invention An embodiment of the present invention will be described based on FIGS. 1 to 8. Two guide shafts 11 are disposed horizontally within a housing-like case 10, and a carrier 12 is attached to these guide shafts 11 so as to be able to reciprocate in the left-right direction. A printing head 13 is placed on this carrier 12. A horizontally long counter electrode 14 is horizontally attached to the center of the case 10 so as to face the printing head 13. A tractor 16 is provided behind the counter electrode 14 to feed a recording paper 15 as a recording medium guided between the counter electrode 14 and the printing head 13. These tractors 16 are coupled with operating knobs 17 that protrude outward.

Here, details of the printing head 13 will be explained based on FIGS. 1 and 3. A housing-like head case 18 is provided, and an ink holding portion 20 for storing ink 19 is formed within the head case 18. The top surface of this ink holding portion 20 is covered with a lid 21 attached to the head case 18. Further, the front wall of the head case 18 serves as a holding plate 22 facing the counter electrode 14,
The rear wall serves as a thick support 23. A plurality of holding holes 24 are formed in the holding plate 22 at equal intervals in the horizontal direction, and communicate with the lower part of the ink holding section 20 . These holding holes 24 are formed in a tapered shape whose diameter decreases as it approaches the counter electrode 14. Further, the inner peripheral surface of the holding hole 24 is a rough surface. On the other hand, a plurality of support holes 25 are formed in the support body 23 at positions facing each of the holding holes 24 . Conductive terminals 26 are fitted and fixed at the rear ends of these support holes 25 .

Therefore, the coil spring 2 having conductivity at the rear end
A plurality of recording electrodes 28 are provided, each of which is wound and fixed. These recording electrodes 28 are made of a material that is electrically conductive but not impregnated with ink, and have tapered ends that match the holding holes 24 . The recording electrode 28 is connected to the support hole 2 on the side of the coil spring 27.
5 and is held by the force of the coil spring 27 pressing the tip against the holding hole 24.

Further, the holding hole 2 is provided on the front surface of the holding plate 22.
4 is sloped in a direction away from the counter electrode 14 from below, and this sloped portion serves as a slope surface 29. The starting portion of this inclined surface 29 is marked with an R. An ink escape groove 30 that hangs down from the lower end of the holding hole 24 and reaches the lower end of the inclined surface 29 is formed on the front surface of the holding plate 22 .

One end of a high voltage switch 32 is connected to the terminal 26 via a connector 31, and the other end of the high voltage switch 32 is connected to two separate high voltage sources 33 and 34. and is connected to the counter electrode 14. Moreover, the high voltage power supply 3
The connection midpoints of 3 and 34 are grounded.

In such a configuration, since the inner circumferential surface of the holding hole 24 is a rough surface, even if the recording electrode 28 is fitted therein, irregular gaps will be created between the two. The ink 19 in the ink holding section 20 is supplied to the tip of the recording electrode 28 through such a gap. Therefore, when the high voltage switch 32 is selectively turned on in accordance with the print signal, a potential difference exceeding a predetermined value is generated for each recording electrode 28, and the ink 19 at the tip of the recording electrode 28 to which the voltage is applied is transferred to the opposite electrode. Fly towards 14.
As a result, dots are formed on the recording paper 15, and printing is performed by a collection of these dots.

On the other hand, during printing, the dots formed on the recording paper 15 are always formed at accurate positions, and stable printing is performed. This means that the positioning of the recording electrode 28 is accurate and that the ink 19 is
This is because it is held only around the tip of 8.
That is, since the positions of the recording electrodes 28 are regulated by the holding holes 24, all the recording electrodes 28 are positioned at the correct positions set in advance, and the tips of such recording electrodes 28 have no ink droplets flying into them. Only enough ink 19 is supplied to do so.
This allows the recording electrode 28 to be accurately positioned.
The ink 19 flies straight from the tip toward the counter electrode 14, resulting in stable printing. In addition, the ink 19 easily separates from the tapered tip of the recording electrode 28, which also allows the ink 19 to fly in an accurate direction.

Furthermore, accidents such as the recording paper 15 being stained with ink 19 during printing are prevented. This is because the electric field tends to concentrate because the tip of the recording electrode 28 is tapered, and even if the recording electrode 28 and the counter electrode 14 are placed apart from each other, the ink does not flow from the tip of the recording electrode 28. This is because 19 will fly. In addition, even if an excessive amount of ink 19 flows out of the outlet of the holding hole 24, the ink 19 flows down through the ink escape groove 30 and does not stagnate around the outlet of the holding hole 24. Further, since the inclined surface 29 is inclined in a direction away from the counter electrode 14, the ink 19 is prevented from flying from this portion. Furthermore, the starting portion of the inclined surface 29 marked with R is spared from concentration of the electric field, and the ink 19 is similarly prevented from flying from that portion. In this way, from the above, undesirable flying of the ink 19 is prevented, and the ink 19
This prevents the recording paper 14 from being soiled by dirt.

Furthermore, since the recording electrode 28 is formed of a straight wire-like member except for a tapered tip, it has good workability. Moreover, such positioning of the recording electrode 28 can be easily performed by simply pressing the tip of the recording electrode 28 against the holding hole 24.

Note that in FIGS. 5 to 8, the recording electrode 28
Here are some examples of variations. First, in the device shown in FIG. 5, a recording electrode 28 is formed by forming a conductive thin film 41 in a line shape on a hard rod-shaped member 40 that does not have conductivity in alignment with the axial direction of the rod-like member 40. It is something. FIG. 6 shows a rod-shaped member 40 in which a conductive thin film 41 is formed on the entire surface thereof. On the other hand, in the case shown in FIGS. 7 and 8, a conductive member 42 is embedded in the center of a rod-shaped member 40 so as to be aligned in the axial direction. Here, the one shown in FIG. 7 is wire-shaped, and the one shown in FIG. 8 is plate-shaped with a cross section.
Moreover, the recording electrode 28 formed in this way is
Both have tapered tips.

Effects of the Invention The present invention provides a printing device in which an image is formed by selectively flying ink attached to the tip of a recording electrode as ink droplets by electrostatic means, in which the recording electrode is not impregnated with ink. The tip of the recording electrode is formed into a tapered shape, and a holding hole with a tapered shape and a rough inner peripheral surface is provided to match the tip of the recording electrode, and the tip of the recording electrode is held in the holding hole. Therefore, it is possible to prevent the recording medium from being contaminated with ink, and to perform good printing with accurate dot formation positions.
Processing and positioning of recording electrodes is also easier.
In addition, when a holding plate having holding holes is provided and an ink escape groove is formed on the surface of this holding plate so that the ink escapes downward from the lower end of the holding hole, excessive ink accumulated at the outlet of the holding hole should be quickly washed away. Therefore, the amount of ink supplied to the tip of the recording electrode can always be kept at an ideal amount, and the ink can be ejected consistently. When a portion is tilted in a direction away from the counter electrode and a radius is marked at the beginning of the slope, the electric field concentration on the portion is weakened, and ink is no longer ejected from unnecessary places, resulting in a recording medium. This has the effect of eliminating the possibility of contamination.

[Brief explanation of drawings]

Fig. 1 shows an embodiment of the present invention; Fig. 1 is a vertical cross-sectional side view showing the connection state between the printing head and the counter electrode, Fig. 2 is a perspective view of the entire printing head, and Fig. 3 is a cross-sectional view of a part of the printing head. FIG. 4 is a side view showing the tip of the recording electrode held in the holding hole, FIGS. 5 to 8 are perspective views showing some modifications of the recording electrode, and FIG. 9 is a conventional one. It is a perspective view showing an example. 14... Counter electrode, 15... Recording paper (recording body),
19... Ink, 22... Holding plate, 24... Holding hole, 28... Recording electrode, 30... Ink escape groove.

Claims (1)

[Scope of Claims] 1. When a counter electrode and a recording electrode having ink attached to the tip thereof are arranged facing each other with a recording body interposed therebetween, and the electric field between these recording electrodes and the counter electrode exceeds a predetermined value. In the printing device in which ink is ejected from the tip of the recording electrode to form an image on the recording medium, the recording electrode is formed of a member not impregnated with ink, and the tip of the recording electrode is tapered. 1. A printing device characterized in that the recording electrode is formed into a shape, and a tapered holding hole with a rough inner peripheral surface is provided to match the tip of the recording electrode, and the tip of the recording electrode is held in the holding hole. 2. A counter electrode and a recording electrode with ink attached to the tip thereof are arranged opposite to each other with a recording body interposed therebetween, and when the electric field between these recording electrodes and the counter electrode exceeds a predetermined value, the tip of the recording electrode In a printing device in which an image is formed on the recording medium by ink flying from a portion, the recording electrode is formed of a member that does not have ink-impregnating property, and the tip of the recording electrode is formed in a tapered shape, A holding plate having a tapered holding hole with a rough inner circumferential surface that coincides with the tip of the recording electrode is provided, and an ink escape groove is formed on the surface of this holding plate that passes downward from the lower end of the holding hole. A printing device characterized in that the tip of the recording electrode is held in the hole. 3. The printing device according to claim 2, wherein a portion of the holding plate below the holding hole is inclined in a direction away from the counter electrode. 4. The printing device according to claim 3, wherein the holding plate is rounded at the beginning of the slope.