JPS5989164A - Multi-nozzle ink jet head unit - Google Patents

Abstract

PURPOSE:To simplify the manufacture of the titled unit by such an arrangement wherein a flexible printed substrate is connected to a head through an electric conductive both side adhesive tape and this joined portion is molded and by this, the manufacture of a head is simplified by reducing the number of parts and the necessity for a high accuracy of processing of elastic members, etc. is eliminated. CONSTITUTION:A flexible substrate (FPC)1 is composed by providing an etched copper foil 3 on a substrate film 2. The edge 4 of this copper foil 3 corresponds to piezo elements 8 of an ink jet head, and a piece of electric conductive both side adhesive tape 5 is pasted to the edge 4. The FPC1 is laid over the head 7 so that the edge 4 of the copper foil 3 corresponds to piezo elements 8 arranged at positions opposing to a pressure chamber 72 interconnecting to nozzles 71 formed on the head 7, and they are pressed together. With this, piezo elements 8 and the edge 4 are pasted together through the tape 5 and the head 7 and FPC1 are integrated. After that, the integrated unit is molded 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-nozzle inkjet head unit having a plurality of ejection nozzles, and particularly to a connection structure between an inkjet head and an FPC for applying a driving electric signal to the inkjet head.

Conventionally, several types of inkjet systems have been proposed in principle, but the present invention is not applicable only to a specific method among them, but as a multi-nozzle inkjet, a voltage is applied to a piezo element. On-demand inkjet and RAD, which eject ink droplets by utilizing the deflection caused by this, are well known, and the following embodiments will be explained using this type of head.

Conventionally, in this on-demand type inkjet head, the electrical connection between the piezo element and the control circuit is performed by soldering a lead wire or the like to the electrode of the piezo element to transmit signals.

With this connection structure, in a head with multiple piezo elements, the work surface is bulky due to soldering to each piezo element, and the vibration characteristics of the piezo element change depending on the amount of soldering. This method has the disadvantage that uniform ink jetting cannot be performed.

As a method to overcome this drawback, the present applicant has proposed
An idea was taken to connect an FPC directly to the piezo element by pressing it as shown in Japanese Patent No. 7-41968. According to this $117 structure, it is possible to completely eliminate the above-mentioned problems in the soldering structure in terms of workability and vibration resonability, and the elastic part H prevents ink from entering the electrical connection part. At the same time, we were able to create a seal structure that prevents such problems.

The present invention aims to reduce the number of parts compared to the above structure, simplify N'j, and easily manufacture the shapes of the elastic part side and head cover without requiring high processing precision. .

This invention creates a reliable and stable connection with a very simple structure by interposing a conductive double-sided adhesive tape between the piezo element and the PC and PC to electrically and mechanically connect them. In addition to molding this connection part, it prevents ink from penetrating into the connection part, and the head unit can be assembled into a variety of shapes depending on the characteristics of the head, as described later. be.

The present invention will be described in detail below as an example (Z), Figure 8A1 d
The FPCL used in the embodiment of the present invention is shown.The FPCL is composed of a copper foil 3 etched in a predetermined shape on a substrate film 2, and the end 4 of the copper foil 3 is attached to a piezo element of an inkjet head. A double-sided conductive tape 5 is attached to this end. Further, the FPC 1 is coated with an overlay 6 for insulation except for the end portion 4 of the copper foil 3.

FIG. 2 is a side view showing electrical connection with the head using this FFCl, and shows a nozzle 71 formed on the head 7.
By stacking and pressing the end portion 4 of the copper foil 3 of Ff'C1 so as to correspond to the piezo element 8 disposed opposite the pressure chamber 720 communicating with the piezo element 8, the conductive double-sided adhesive tape is attached to the piezo element. 8 and the end 4 are electrically connected, and are also mechanically bonded.
PCI Toka becomes one. Next, this electrical connection part is molded 9 in order to protect it from ink and the like. This mold 9 allows the head 7 and the FPCI to be more strongly integrated. The above configuration is sufficient for the head unit, but it is necessary to fix the head unit to the carriage in order to fix the recording device i'J Ic 1. Cased with a pair of headcover rivers, II.

In the above configuration, since the conductive double-sided adhesive tape is attached to each end of the FPC after it is manufactured, it can be treated as one component when assembling the head unit, and furthermore, it is possible to simply press the FPC and head together and press them together. Since the head and FPC can be integrated electrically and mechanically, a reliable and stable connection can be achieved with a very simple configuration. Furthermore, by molding the connection part, it can be protected from ink, etc., so there is no need to consider sealing etc. as a head cover, so a simple shape is sufficient, and high processing precision is not required. have

Conductive double-sided adhesive tape is a double-sided adhesive tape used for office purposes that contains a conductive material (e.g. carbon powder,
Various methods have been devised for tape base materials and adhesives that are likely to be contaminated with conductive materials. In addition to the above-mentioned type that simply presses, there are also types that use heat and press to increase the adhesive strength.

Even in the above-mentioned embodiments, if the heat-pressing jig is devised, a highly reliable head unit can be constructed using this type of conductive double-sided adhesive tape.

Furthermore, the configuration described above can be implemented in various ways in various inkjet heads depending on the characteristics of the head, as described below. FIG. 3 shows one embodiment of the present invention, in which the head 21 is made of a fragile material such as glass or ceramic, and the head 21 and FPC 22 are connected in the same configuration as in FIG. 2. Head 21 and FPC
After the parts 22 are integrated, they are molded into a sawn mold, and several holes 24 for the carriage etc. are also formed at the same time, and the head cover described in FIG. 2 is omitted.

FIG. 4 shows another embodiment, which is applied to an inkjet head 5 made of plastic, and the head 5 has several holes 26.
is formed from the beginning, so head 5 and p p c
27 was connected in the same manner as described above, and only the necessary parts were molded. It is very effective in that it implements the advantages of an inexpensive, mass-produced ink-shed head made using Buostick's injection molding in this very simple and easily automated method.

FIG. 5 shows still another embodiment, in which head addition and F P
C31 is connected in the same way as each side above, but F P
A head drive mechanism C32 is mounted on C31.

Methods for mounting ICs on FPCs, such as face-down bonding, have already been put into practical use, and this technology is often used.

As shown in the block diagram of Fig. 6, the head driver IJIj C32 reads the electrical signals for driving each piezo element of the head 30 serially and outputs them in parallel, thereby producing a multi-nozzle system with multiple nozzles. The number of drive signal terminals for the nozzle inner jet head can be reduced.

For example, in a head with 24 nozzles, if such an IC is not mounted, add +1 (1 digit ') as an FPC terminal.
+f) J ground fin) is necessary, but this work C32
If you use , you will only need about 6 terminals as described below.

Note that the reference numeral 33 is the one molded with a mold, as described in FIG.

By molding the mounting portion of the head drive IC 32 at the same time when molding the connection portion between the head (g) and the F p c 31 in this way, the effect of this molding is further enhanced.

FIG. 6 shows a block diagram of the head drive mechanism C32 used here. 34 is a shift register into which serial data is input from one data input terminal 35.

Naturally, this data reading is performed in synchronization with the clock input to the clock input terminal 36. A latch 37 latches the contents of the shift register 34 to the input of a latch clock 38. and head fiber with latched data.
39 is ON-OFF controlled, and its output 40 selectively de-fibs the piezo element of the head. Note that VI) D is the power supply terminal (usually 5V) for the logic part of the shift register 34Φ], and VH is the high voltage power supply terminal for the head fiber (100V).
-200V), which is the ground terminal for all GNld circuits.

The above is the head gA mounted on the FPC shown in Fig. 5!
This is an example of the IC, but by using such an IC, apart from the power supply fin, it is possible to control the data output 35, clock power 36, and latch clock 38; It is possible to transfer print data and drive the head.

The present invention has been described above with reference to various embodiments, but as stated at the beginning, the principle of the present invention is that it can be applied to any multi-nozzle head other than an on-demand inkjet head that ejects ink by driving a piezo element. It should be clear from this.

As described above, the present invention is directed to a multi-nozzle inkjet head for driving 1 (l, pP
C is connected to the head by intervening double-sided gradient tape.By molding this connection part, a reliable and stable connection can be made with a very simple configuration.Sudden bending can be done mechanically. In addition, the mold protects it from ink, etc., and it is also highly compatible with a variety of heads.
This contributes to higher reliability and lower cost of inkjet heads.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an FPC used in one embodiment of the present invention, FIG. 2 is a diagram showing one embodiment of an inkjet head unit of the present invention, and FIG. 3 is a diagram showing another embodiment of the present invention. The figure shows still another embodiment of the invention, FIG. 5 shows still another embodiment of the invention, and FIG. 6 shows a block diagram of a head drive IC used in the embodiment of FIG. 1. @FPC 5. Conductive double-sided adhesive tape 7. Inkjet head 91 mold lfl, 11". Head holder 32.. Head drive IC Applicant Nibunon Co., Ltd. Agent Patent Attorney Mogami 24 Figure 3 Figure 4

Claims (1)

[Claims] an inkjet head having a plurality of ejection nozzles and a pressure chamber communicating with the ejection nozzles; a piezo element disposed opposite to the pressure chamber; a flexible printed circuit board for applying an electric signal to drive the piezo element; A multi-nozzle inkjet head characterized by comprising a conductive double-sided adhesive tape interposed between the piezo element and the flexible printed circuit board for electrical and mechanical connection, and a molding material that covers at least the electrical connection portion. unit.