JPS585263A - Multi-nozzle jet head for ink jet printer - Google Patents

Abstract

PURPOSE:To upgrade the quality of printing as well as reduce noise durig the operation period by removing the interaction between pressure chambers by pressingly providing an elastic material to the flexible walls of the pressure chambers. CONSTITUTION:In the first plate 1, a concaved part 1a is formed by etching and its thin-thickness part constitutes a flexible wall 1b. Also, in the space formed by the surface of the second plate 2 and the inner surface of the concaved part 1a, a pressure chamber 3 is formed, receiving ink 6 through a pipeline 5 from an ink storage chamber 4. Also, the flexible wall 1b of the first plate 1 is bonded with a piezo-electric crystal 7, and an elastic material 10 formed of a non-conductive rubber is provided in a compressed state between the flexible wall 11 and the cover 12. Thus, the vibration of the flexible wall 7 is quickly damped by the elastic material 10, and therefore, the vibration is not transmitted to the other pressure chamber 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a jetting head for an on-demand type inkjet printer. A multi-nozzle for an inkjet printer consisting of a mechanical conversion head as an image layer [relates to the ejection head].

Inkjet printers can be broadly divided into on-demand printers that eject a small amount of ink only when needed, and high-speed printers that eject a small amount of ink all the time. Comparing these three systems, in the case of the continuous type, a pressure power source on the order of kilovolts is required in order to generate a small ink deflection field of 1liii+t-. Furthermore, since ink is constantly ejected and a collection meeting for ink used for construction is also performed, the ink circulation mechanism becomes complicated. As a result, there is a drawback that the equipment becomes very difficult to operate. In comparison, the on-demand type can eject a small amount of ink with a low voltage (for example, about 100 V), and because it only ejects ink when it is necessary, the ink circulation mechanism is unfavorable. Since the feeding mechanism is very simple, it is possible to make klK smaller. The on-demand type, which has these advantages, also generally has a lower drive frequency than the continuous type, so the on-demand type has this advantage.

The jet head is made into a multi-nozzle by arranging multiple pressure chambers containing metal to increase the speed ratio and resolution of the inkjet printer by 1%. However, each pressure chamber is not completely independent from each other, and is connected to other pressure chambers through the pressure chamber walls and all ink valves.

For this reason, a phenomenon called pressure chamber interaction (or channel interaction) exists. This is because #RjllilI of the flexible wall of the pressure chamber propagates to other pressure chambers, so when driving multiple pressure chambers at the same time, compared to driving only one pressure chamber, , which is a phenomenon in which the flight speed of an ink droplet fluctuates sharply as the driving frequency increases.

Figure 7 is a frequency-time diagram to explain this dust phenomenon.
The horizontal axis shows the drive frequency of the pressure chamber, and the vertical axis shows the number of ink irregularities. The characteristic l1iIA in this figure represents the flight speed of the ink droplet ejected from the nozzle when only a single pressure chamber is driven. As is clear from this physical property curve, when only a single pressure chamber is driven, the flight speed of the ink droplet does not change much even if the driving frequency changes, but when other pressure chambers are driven at the same time. Then, as shown by the physical property -IwB, the characteristics and physical properties vary greatly as the driving frequency increases. Such large fluctuations in flight speed can lead to severe degradation of print quality and sometimes even stop the ejection of ink droplets.

The present invention has been made in view of these points, and by press-contacting an elastic body to the flexible wall portion, interaction between pressure chambers is eliminated, printing quality is improved, and the structure is simple and the drive is simple. The present invention provides an i-multi-nozzle ejection head for an inkjet printer that produces little noise.

The present invention will be described in detail with reference to Figure vE11i below.

FIG. 2 is a sectional view showing an embodiment of the jet head according to the present invention, and FIG. 3 is a cross-sectional view of FIG. It is a good road cob plate which is arranged opposite to the plate L.A recess/mdi is formed by the esonang in the above-mentioned 1st plate)/.
The thin part is flexible @/b. Further, the space formed by the surface of the #4 cob plate λ and the inward direction of the recessed portion /a constitutes a pressure chamber 3, and is supplied with an ink base from an ink storage Wi through a conduit j. 7 is the first plate l
An electrical/mechanical conversion element (hereinafter, a piezoelectric crystal is exemplified as #; 1) glued to the flexible wall of
．． (to be explained later), and is driven by a pulse generator @1 that sends out electric pulses in accordance with recorded information. This is a nozzle for ejecting ink 1t inside the pressure chamber 3 to the outside. A plurality of pressure chambers 3 are formed 9 in a direction perpendicular to the paper plane of FIG. 2, and each pressure chamber 3 is provided with the nozzle and the piezoelectric crystal 7.

10 is possible! @Wall portion//An elastic body placed in a compressed state between the flexible wall and its surrounding area, which also includes 7 tons of piezoelectric crystals, and the cover saw. It is formed of conductive rubber material. Since the elastic body IO is placed in a compressed state, the elastic body 10I/) will be pressed against the flexible wall portion.

The pressure chamber J of the ejecting head configured in this way, the interior of the nozzle, the ink storage chamber, and the pipe line! It is filled with 9 ink 1 supplied through. Therefore, when an electric pulse that causes the piezoelectric crystal 7 to deform inward is applied, the flexible wall lb also bends inward, the volume of the pressure chamber 3 rapidly decreases, and the ink base in the pressure chamber 3 is reduced. part is injected at high velocity to the outside through the nozzle. On the other hand, a part of the ink group passes through tji6jt and enters the ink storage chamber 4tIIl.
Return to 1. Immediately after ejection, the ink group ejected outward through the nozzle becomes a spherical ink droplet due to surface tension. The diameter of this ink droplet is determined by the inner diameter of the nozzle, the voltage level of the electrical pulse, the rise time constant, and the pulse width. The volume of the pressure chamber 3 is restored after a period of time corresponding to the pulse width of the above-mentioned demonic energy pulse has elapsed, and at the time of this restoration, the pressure chamber 3 is supplied with ink base from the ink storage chamber.

In the case of the above injection head based on Il, the flexibility Ii of the pressure chamber 3
Since the vibration of the pressure chamber 7 is rapidly attenuated by the elastic body io and is not transmitted to other pressure chambers 3, there is almost no interaction between pressure groups. Therefore, a frequency characteristic equivalent to that of a person in %/figure can be obtained.

Fig. 3 shows another embodiment of the present invention, which differs from the ejection head shown in Fig. 2 in that a pace plate T is provided and nozzles are arranged on both sides thereof. That is, λl is the base plate,
This is a side plate placed at # of the 2311-1 base plate V-to 2/. This side plate λλ,
A recess 5JullJJ& is formed in λ3, and the thin portions thereof are flexible M here b and Jjb. or,
The space formed by the surface of the base plate 1 and the inner surfaces of the concave S's a and 3a forms a pressure chamber, 2≠, λj, and is supplied with ink from an ink storage chamber. 24.27
are the piezoelectric crystals glued to the side plates λ, 23's flexible parts 82 and 3b, 21. -ta are nozzles for ejecting ink inside the pressure chambers to the outside.

A plurality of these nozzles λt, λ, pressure chambers KO, λj, etc. are provided in a direction perpendicular to the plane of the drawing of Me with the base plate 1 in between. 30 is possible! @An elastic body placed in a compressed manner between the wall portion 31 and the cover 32, 33 is OK!
It is an elastic body placed in a compressed manner between the wall portion 3 and the cover 35. Both elastic bodies 30. JJ and others, th
Since the flexible wall portions 3 and 3 are pressed against each other, no interaction occurs between the pressure chambers in this embodiment due to the same principle as in the M-diagram embodiment.

wJ! The figure is tA4! In Figure 0, which is a perspective view showing a specific example of the jetting head shown in the figure (the cover is not shown), 4tO is the laminated plate portion in which pressure fugin is formed %≠ / is the laminated plate portion 〇 This is the pulp section for supplying ink from the outside. The ink passing through the valve section -/f is temporarily stored in the common ink tank, and then sent to each pressure chamber. And, each pressure amount is possible! l! j
By the llK-contacted piezoelectric crystal da3,
From the nozzle, it is sprayed to the outside again. rij is an elastic body pressed against the flexible m* part, and the piezoelectric crystal≠3 is held by this. Of course, in this embodiment, no pressure chamber interaction occurs.

As described above, according to the present invention, since no pressure-chamber interaction occurs, it is possible to obtain an ejecting head' with high print quality. In addition, since the wall portion is covered with an elastic body, driving noise can be reduced.

Moreover, these effects are mainly achieved by the extremely simple structure of pressing the elastic body. Note that using non-conductive rubber as the elastic body is the most advantageous in terms of cost and properties.

[BRIEF DESCRIPTION OF THE DRAWINGS] Figure A: Frequency characteristic diagram of a conventional injection nozzle; 12- is a cross-sectional view showing an embodiment of the present invention; Figure 3 is a cross-sectional view of the Konko diagram; Fig. V is a sectional view showing another embodiment of the present invention, and Fig. 3 is a perspective view showing a specific example of the injection nozzle shown in Fig. 2. λ7~ko3... plate 3. Ko Hiro!・・・
・Specific force chamber/b, λb, JJb...flexible wall 7.2 &, core...piezoelectric crystal (electrical/mechanical conversion element), Jf, λri...nozzle 10. J.O., J.J.
...Elastic body //, 31. II...Flexibility *S min/2
．． JJ, Jj...f2 Bar patent applicant Roku I Konishi
X Koto Co., Ltd. Agent Bench Haruatsu Doijima 1 Figure 1 2 3 4 Drive frequency i number (kHzl Figure 2 Procedural amendment (voluntary) 1. Indication of matter f1 1982 Patent Application No. 100232M 2, Invention Name of inkjet printer tj3 multi-nozzle recording head 3, person making the correction, etc. Patent application Person address 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Name (Name) (127> Roku Konishi Photo Industry Co., Ltd. Representative: Nobuhiko Yomoto, 40s, 107 Address: Akasaka Mizutani City Plaza, Room 404, Room 5, 1-8-1 Akasaka, Minato-ku, Totobu Column and drawing 6, contents of amendment (1) Change [-pressure chamber] in line 8 of page 3 of the specification to [
"One Ti-horn room," he corrected. (2) “Part 1 of ink 6” on page 6, line 9 of the specification
11 is corrected to "a part of the ink filled in the force chamber 3". (3) [Rise time constant-] on page 6, line 14 of the specification
[, a falling time constant 1 is added between 1 and 1 and 1. (4) "Flexible membrane 1" in lines 17 to 18 on page 8 of the specification is corrected to "flexible wall." (5) Figure 1 of the drawings will be corrected as shown in the attached drawings. Below

Claims (2)

[Claims] (1) A multi-nozzle ejection head Ic for an inkjet printer consisting of an electromechanical transducer that bends in accordance with external No. 16 is adhered to the flexible wall of each pressure chamber, and an elastic body is attached to the flexible wall portion. A multi-nozzle ejection head for inkjet printers characterized by pressure contact. (2) A multi-nozzle ejection head for an inkjet printer according to claim 1, wherein the elastic body is a tube made of non-conductive rubber and t% mold.