JPS5989162A - On-demand type ink jet head - Google Patents

Abstract

PURPOSE:To cause the electrode of a piezo element to positively contact with a flexible printed circuit board, remove high harmonic component and expedite the attenuation of vibration by interposing an electric conductive elastic member between the piezo element and the board. CONSTITUTION:A flexible printed circuit board 3 (EPC) is applied to piezo elements 2 of a head body 1 through electric conductive elastic members 10 (preferably electric conductive rubber) and they are compressed from both sides by head covers 4 through No.2 elastic members 5 applied to the back of FPC3. The FPC3 has a contact part 39 which is brought to contact with electrodes of piezo elements 2 and a wiring unit 37 connecting to external circuits, and this wiring unit 37 is coated with insulation covering 38. EFFECT:Even if individual piezo elements are uneven in height and the contact part 39 of FPC3 is lower than the insulation covering 39, the contact part 39 of FPC3 can be positively and electrically connected to piezo elements 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an on-demand type inkjet recording head, and more particularly to the structure of an electrical connection between a piezo element and a control circuit.

Conventionally, far-off connections between piezo elements and control circuits were carried out by soldering lead wires etc. to the electrical components of the piezo elements. In this connection structure, multiple piezo elements have The head had disadvantages in that it took many man-hours to solder each piezo element, and the vibration characteristics of the piezo element changed due to soldering electricity, making it impossible to eject ink uniformly.

The present applicant has proposed a method for solving this drawback in Japanese Patent Laid-Open No. 5
It was proposed that a flexible printed circuit board as shown in Japanese Patent No. 7-41960 be directly pressed against the piezo element to establish a pneumatic connection with the control circuit.

In this structure, as shown in FIG. 5, the piezo element 2KFPcs% on the head body 1 is brought into contact with the
The elastic member 5r valve is held down by the head cover 4. Reference numeral 6 denotes a supply port for supplying ink to a pressure chamber (not shown) formed in the head body 1.

According to the structure shown in FIG. 5, the disadvantages of the above-mentioned soldering structure can be completely eliminated in terms of drawing efficiency and vibration characteristics.

The present invention is an improvement over the previous proposal, and its purpose is to improve the contact area 44 between the electrode of the piezo element and the flexible printed circuit board.

The present invention is characterized in that a conductive elastic part is placed between the piezo element and the FPC, and the electrical connection between the two is adequate, and when the piezo element is driven, 9 harmonics are generated. This is aimed at suppressing vibrations and speeding up vibration damping.

One embodiment of the present invention is shown in FIG. FIG. 1 shows the various members constituting the inkjet head of the present invention.
FIG. 3 is a side view exploded for ease of use.

In FIGS. 1 to 3, the fifth
Components with the same number 7 as in the drawings indicate those with the same functions.

Reference numeral 10 denotes an elastic member having electrical conductivity, which is a feature of the present invention. As is clear from the figure, VPCS is applied to the piezo element 2 of the head body 1 via the conductive elastic member 10, and the VPCs are applied to the back side of the FFO 3. ) It is pressed from both sides by the head cover 4 via the elastic member 5.

Pressed state 11 - shown in FIG. Further, as shown in FIG. 3, the FFO 3 has a connection part 59 that contacts the electrode of the piezo element 2 and a wiring part 37 that connects to an external circuit (drive circuit, etc.), and this wiring part 37 is connected to an insulating coating 38. is coated.

The conductive member 10 may be any material as long as the conductor 1 is made of a polymeric material, conductive rubber, metal spring, or the like, and has an elastic material. Among these, conductive rubber is the most suitable because it is thin, has good connection performance, and does not require a lot of assembly work. This conductive rubber is made of metal or carbon mixed therein, has conductivity in the thickness direction V, or has 24F-TW conductivity only in the contact with the piezo element, and is sized to meet the piezo element. Just put it on top.

According to the above method, if the present invention is used, there will be a gap between the FPC and the piezo element! Even if the Lv1 individual piezo elements are uneven, the fc
Even if the connection portion 59 of the FPo is lower than the insulation coating 5B, the connection 8I139 of the FFO and the piezo element 2 can be reliably electrically connected.

Further, a voltage is applied to the piezo element 2 and the conductive member 10
Even if it is pushed in the opposite direction, the piezo element 2 and the connecting portion 39 will not come out of contact because they are pressed with elasticity.

In addition to improving connection reliability as described above, the conductive member having elastic properties of the present invention also has the following effects.

In an ink jet recording apparatus, the timing of ink jetting is determined by the vibration #iJJ characteristics of the vibration system including the piezo element, the head body, and the ink chamber. Since the j-note changes greatly, it is desirable that the S dynamic system has less harmonic vibration after ink ejection, and that the vibration is reduced quickly.

Figure 4 V? - shows the vibration characteristics of the vibration system when the conventional electrical connections are made (curve 11A) and the vibration characteristics of the vibration system when the electrical connections of the present invention are made (curve B). ing. As is clear from the figure, compared to the conventional example, an electrically conductive member having elasticity is interposed between the piezo element of the present invention and the FPC, and harmonic components are removed due to the structure, and vibrations are further reduced. Tears can also be made faster and stable ink jetting characteristics can be obtained.

[Brief explanation of the drawing]

Fig. 1 is an exploded side view showing a refreshing embodiment of the present invention, Fig. 2 is a partially enlarged view showing the densely layered state of wJ1 Fig. 5, and Fig. 5 is a #P rule diagram of FPC. . FIG. 4 is a diagram showing a comparison of the vibration characteristics of the conventional vibration system and the vibration system of the present invention. FIG. 5 shows a conventional example. 1...Head body 2...Piezo X-child 3...
FPO4... Head cover 5... Elastic member 10... 5 Abrasive guiding member having QI properties and above Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] It has a head body formed with a pressurizing chamber and a nozzle, and a piezo element disposed at a position facing the pressurizing chamber, and uses the light generated by applying tortoise pressure to the piezo element to In an on-demand inkjet head that ejects ink droplets from a nozzle, a flexible printed circuit board for connecting a front six piezo element and a control circuit that selectively generates a voltage signal; A first 9Iti material having conductive ridges disposed between the elements, a second elastic member bonded to the flexible printed circuit board, the piezo element, the first '31atJ material and the flexible printed circuit board. An on-demand inkjet head comprising a printed circuit board and a head cover that presses the second elastic member.