JP3171219B2 - Inkjet recording head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head using a vibrator of a longitudinal vibration mode, and more particularly to a connection structure between a piezoelectric vibrator and an external drive circuit.

[0002]

2. Description of the Related Art In an ink jet recording head in which a vibrator vibrating in a longitudinal direction is brought into contact with a pressure generating chamber to fly ink droplets from nozzle openings, the width of the pressure generating chamber can be made extremely small. It is characterized in that the density can be increased to about 180 DPI and the size of the recording head can be reduced. Since such a recording head is extremely small, the circuit board on which the drive circuit is mounted and the connection means for the ink tank are both mounted on the base as shown in FIG. 13, and the base is mounted on the recording head and the carriage. It is configured to also serve as a base. By the way, when the recording density is increased to about 180 DPI, the arrangement pitch of the vibrators constituting the pressure generating means becomes extremely small as about 140 μm, so that a conductive pattern for supplying a drive signal for driving the piezoelectric vibrator is provided. There is a problem that erroneous connection or short circuit is easily caused when connecting the piezoelectric vibrator to the electrode.

In order to solve such a problem, for example, as shown in Japanese Patent Application Laid-Open No. 4-31867, a piezoelectric vibrator of a longitudinal vibration mode is formed by passing one end of the piezoelectric vibrator from a base. A part of the electrodes formed on the side surface of the vibrator is exposed to the circuit board side, and the exposed part is directly soldered to a circuit pattern or connected via a wire. However, as described above, when the recording density is improved, the distance between the piezoelectric vibrators becomes extremely small, so that it is extremely difficult to perform soldering on the side surfaces of the piezoelectric vibrators, thereby causing a connection error such as a short circuit. There is.

In order to avoid such a problem, as shown in FIG. 13, a flared lead frame 62 # is formed on a circuit board 60 side on which conductive patterns 61, 61, 61 # are formed.
A method of connecting directly or indirectly to the side surfaces of the piezoelectric vibrators 64, 64, 64 # via ‥ has been previously proposed. According to this, when the positioning between the substrate and the piezoelectric vibrator is performed, the work efficiency of the alignment is improved as compared with the conventional method of connecting each vibrator individually, but the lead frame 62 is still made of a hard material. However, there is a disadvantage that the alignment is relatively difficult, the working efficiency as a whole is low, and the electrode film of the connecting portion is peeled off, which easily causes a conduction failure. When focusing on workability, it is necessary to secure a sufficient size for the spacing between the conductive patterns 61, 61, 61 #, so that the lead frame 62 inevitably becomes large, and the communication of the ink tank connecting means 65 is inevitable. Hole 6
Between the nozzle frame 8 and the nozzle opening 67 is the lead frame 62.
Is increased by the height ΔH. That is, when the ink tank is pulled out of the ink tank connecting means 65 for ink supply or the like, the negative pressure of the head difference becomes larger than the surface tension in the communication hole 68, and air flows from the communication hole 68 to the ink supply path 69. There is a problem in that the intrusion occurs and printing failure occurs during subsequent printing. In particular, when the number of nozzle openings increases, the height ΔH dramatically increases.
On the other hand, in order to avoid this, it is necessary to mount the ink tank connecting means 65 below the circuit board 60, and to make the ink tank connecting means 65 project laterally as shown in FIG. Not only complicates the structure, but also increases the overall size of the head,
Accordingly, various problems such as a long ink supply path and a large pressure loss during ink ejection are caused.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and an object of the present invention is to simplify the operation of connecting a piezoelectric vibrator to an electrode, and to simplify the connection between a recording head and a recording head. An object of the present invention is to provide an ink jet recording head capable of solving the above-mentioned inconvenience by reducing a step with an ink supply means.

[0006]

Means for Solving the Problems] inkjet recording head of the present invention in order to solve such problems, a piezoelectric vibrating material and the electrode becomes one pole by alternately laminating electrode parallel <br/> column A piezoelectric vibrator having a common external electrode connected to the external vibrator and a driving external electrode connecting the electrode serving as the other pole in parallel is fixed on a fixed plate so that the end on which the driving external electrode is formed is a rear end. A piezoelectric vibrating unit fixed to the piezoelectric vibrator; an ink flow path forming member that abuts on a tip of the piezoelectric vibrator to generate ink droplets by elongating the piezoelectric vibrator; a base for fixing the ink flow path forming member on the side, and a connection circuit board conductive pattern is formed in accordance with the arrangement pitch of the piezoelectric vibrator
Wherein the connecting circuit board such that the conductive pattern to form a driving external electrode and the conductive relationship of the piezoelectric vibrator before
It is fixed to the other end of the base.

[0007]

[Function] A plurality of piezoelectric vibrators integrated in a unit are
Of the connection circuit board that is the drive signal supply member
It is conductively connected with as small a gap as possible.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and 2 show one embodiment of the present invention. In the drawings, reference numeral 1 denotes a nozzle plate having nozzle openings 2.2, 2２ ， formed at a predetermined pitch, for example, 180 DPI. . Numeral 3 is a spacer having through holes 4, 5, 5, 5 # which are sandwiched between a later-described diaphragm and the nozzle plate 1 to form a reservoir and a pressure generating chamber. Reference numeral 6 denotes a vibration plate which forms a pressure generating chamber facing the nozzle plate 1 with the spacer 3 interposed therebetween, and which comes into contact with a tip of a piezoelectric vibrator 7 described later and responds to expansion and contraction of the piezoelectric vibrator 7. is there.

Reference numeral 7 denotes the above-described piezoelectric vibrator. As shown in FIG. 3, one half is fixed to the fixed substrate 8 at a fixed pitch, and the other half is capable of vibrating in the longitudinal vibration mode.
It is summarized as. As shown in FIG. 4, each piezoelectric vibrator 7 is configured by alternately stacking a piezoelectric vibration material 10, a drive electrode 11, and a common electrode 12 in a sandwich shape. The drive electrodes 11, 11, 11 # are exposed from the end face on the rear end side of the piezoelectric vibrator 7, are connected in parallel by a drive external electrode 14 formed by vapor deposition or the like. , 12} are exposed on the free end side of the piezoelectric vibrator 7 and extend to the side.
5 are connected in parallel.

The driving electrodes 11, 11, 1 of each piezoelectric vibrator 7
The driving external electrodes 14 connected in parallel with each other are positioned so that the end faces thereof are substantially flush with the fixed substrate 8, and the common external electrodes 1 of the piezoelectric vibrators 7, 7, 7 # are connected.
Numeral 5 is connected via conductive members 17 to electrodes 19 on the rear end face of dummy vibrator 18 located on both sides of vibrators 7, 7, 7 # so as to have a conductive relationship. Damper vibrator 18
An electrode 19 is formed on the rear end surface in the same manner as the drive external electrode 14, and can be connected to a connection circuit board 30 described later.

Returning to FIG. 1 and FIG.
Stores the vibrator units 9 and 9 in the unit housing holes 21 so that the free end side of the piezoelectric vibrator 7 is exposed on the base,
Nozzle plate 1, spacer 3, diaphragm 7
Frame 2 that also serves as an electrostatic shield by positioning
2 to form a recording head body.

On the other hand, at the other end of the base 20, the driving external electrodes 14, 14, 14 # of the piezoelectric vibrators 7, 7, 7 # exposed from the unit accommodation hole 21 and the dummy vibrator 1
A connection circuit board 30 to be described later is connected to the electrodes 19 of 8, and further connected to a circuit board 34 via the board as necessary. The lead piece 23 of the frame 22 is connected to the ground of the circuit board 34 to provide a shield.

As described above, the recording head body is connected to the circuit board 34.
At this stage, the ink supply means 38 connected to the other end of the flow path forming member 37 having one end connected to the pressure generating chamber of the print head is fixed to form a print head. In this embodiment, the ink supply needle 39 is provided to penetrate the tank because the ink is supplied by the detachable tank C. However, in the case of a disposable type, the flow path constituting member 37 is connected to the ink tank. You may make it.

FIGS. 5 and 6 show an embodiment of the above-described connection circuit board. In the drawings, reference numeral 30 denotes the above-described connection circuit board, which is provided on the surface of a heat-resistant flexible film 42. One end has a piezoelectric vibrator 7, 7, 7 ° and a dummy vibrator 1
Lead-out portions 44 are formed in accordance with the arrangement pitch of 8, 18 and conductive patterns 48, 48, 48 # provided with divergent portions 46 so as to be continuous with the arrangement pitch of the connection ends of circuit board 34. , 49, 49 are formed in two layers on the front and back sides, and the conductive patterns facing each other on the front and back sides are connected via through holes. And among these conductive patterns,
The outer patterns 49, 49 are the dummy vibrators 18, 18
These are connected to the common external electrodes 15, 15, 15 # of the respective piezoelectric vibrators 7, 7, 7 # via the electrodes 19, and are slightly wider. In this embodiment, since two vibrator units 9 are accommodated in the base 20, two sets of conductive patterns are formed so as to be line-symmetrical in accordance with the accommodation form of the vibrator units 9, 9. ing.

The connection circuit board 30 thus configured
Means that the tip of the pattern is a piezoelectric vibrator 7, 7, 7 ‥‥,
The electrodes are aligned so as to match the electrodes 14, 14, 14 #, 19, 19 formed on the rear end surfaces of the dummy vibrators 18, 18, respectively (FIG. 7). The welding means T such as a metal is pressed against to apply energy necessary to melt the easily melted metal forming the conductive patterns 48 and 49 (FIG. 8).

As a result, the connection circuit board 30 receives the pressing force and receives the piezoelectric vibrators 7, 7, 7 # and the dummy electrodes 19.
All the drive external electrodes 1 are appropriately bent according to the end face shape of the
4 and each conductive pattern 48, 4
8, 48 {49, 49 withdrawing portions 44, 44, 44}
The surface of ‥ is dissolved, and each conductive pattern 48, 48, 48 ‥
‥, 49, 49 are welded to the end faces of the piezoelectric vibrators 7 and the dummy electrodes 18 (FIG. 9). Naturally, the thickness of the easily soluble metal layer such as solder forming the conductive pattern is 2
Since it is about 10 μm, it does not flow out into a gap that secures a pitch of about 180 DPI to short-circuit adjacent driving external electrodes by a bridge.

At the stage where the connection circuit board 30 is welded to the recording head body in this manner, if necessary, the second board 34 is interposed and reinforced, and then the conductive patterns 48, 48,
When the other ends of 48 °, 49, and 49 are welded to the pattern of the circuit board 34 on which the drive circuit is mounted in the same manner, each piezoelectric vibrator 7 is connected to the drive circuit. According to this embodiment, the bottom surface of the vibrator unit 9 and the circuit board 34
Can be fixed at substantially the same height, so that the head difference between the nozzle opening and the ink supply port can be made smaller by ΔH than when a lead frame is used.

In the above-described embodiment, the conductive patterns are formed on both sides of the flexible film 42 forming the connection circuit board 30. However, as shown in FIG. A conductive pattern 44 'similar to that described above is formed only on the surface, that is, on the side of the piezoelectric vibrator facing the driving external electrodes 14, 14, 14 # and the common external electrode 19, and electronic components and the like are mounted. When the circuit board 34 made of a hard material is mounted on the base 20 of the recording head, the driving external electrodes 14, 14, 14
(4) By providing the through holes 45 for exposing the common external electrode 19, the circuit board 34 is mounted on the base 20, and then the conductive pattern of the connection circuit board 30 is
It is apparent that the same effect is obtained even when the connection is made at 4, 14 ° and 19 in opposition.

Further, in the above-described embodiment, the connection is made directly to the conductive pattern formed on the connection circuit board. However, a tab such as a copper foil is formed at the end of the conductive pattern, and the tab or the like is formed. It is clear that the same effect is obtained even when a solder cream is applied to the electrodes of the piezoelectric vibrator and connected by a soldering method. In addition, by mounting the drive IC on the connection circuit board 30 itself, the circuit board 34 for mounting electronic components can be eliminated to reduce costs.

FIG. 11 shows a second embodiment of the connection circuit board used in the present invention.
A substrate 52 provided with windows 51 for exposing at least the piezoelectric vibrators 7, 7, 7 # of the vibrating units 9, 9 exposed from the bottom surface of the recording head body and the end faces of the dummy vibrators 18, 18 includes: The conductive patterns 53, 53, 53 # connecting the piezoelectric vibrators 7, 7, 7 # and the driving external electrodes 14, 14, and the electrodes 19, 19 of the dummy vibrators 18, 18 with the pattern of the circuit board 34. , 54, 54 are formed.

The connection circuit board 50 thus configured
With the conductive patterns 53, 53, 53 #, 54, 54 facing up, the respective conductive patterns 53, 53, 53 #, 5
4, 54 and 54 are positioned so that the connection points thereof face the piezoelectric vibrators 7, 7, 7 # (FIG. 12).
7, 7}, and electrodes 14, 14, 14 of the dummy vibrator.
‥‥, 19, 19 are connected by wires 56, 56, 56 by a wire bonding method. According to this embodiment, not only is the degree of freedom of alignment between the connection circuit board 52 and the vibrator units 9 and 9 relatively high, but also the rigidity of the connection circuit board 50 and the base 20 If the substrate 50 is fixed with an appropriate adhesive, the substrate 50 can also be used as a circuit substrate for mounting the drive circuit, and the cost can be reduced.

In the above-described embodiment, the wires are connected to the conductive pattern formed on the connection circuit board. However, a tab such as a copper foil is formed at the end of the conductive pattern and the tab is formed. Obviously, a similar effect can be obtained even if the connection is made by a wire via the wire.

[0023]

As described above, in the present invention,
Piezoelectric vibrators with common external electrodes connected to the piezoelectric vibrating material and the electrode becomes one pole by alternately laminating electrode in parallel, the driving external electrodes connecting the electrode serving as the other pole in parallel
And a piezoelectric vibration unit configured to secure the ends of drive Dogaibu electrode is formed on the fixed plate so as to the rear end,
The tip of the piezoelectric vibrator comes into contact with the tip of the
An ink flow path forming member that generates ink drops, and a piezoelectric vibrating unit.
The ink flow path forming member is fixed to one end side by housing the ink cartridge.
Conductive pattern matching the base and the pitch of the piezoelectric vibrator
Comprising a connection circuit board for down are formed, a conductive pattern to form a driving external electrode and the conductive relationship of the piezoelectric vibrator
Uni connection circuit board than is fixed to the other end of the base, it can be carried out connecting work to the end face being open in comparison to the transducer side, the recording with high reliability and workability header
And a part that supplies drive signals to the piezoelectric vibrator.
Material can be pulled out perpendicular to the piezoelectric vibrator,
The height of the entire recording head can be kept low.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a pressure generating member of the same device.

FIG. 3 is a perspective view showing one embodiment of a vibrator unit.

FIG. 4 is a cross-sectional view showing one embodiment of a piezoelectric vibrator.

FIG. 5 is an enlarged perspective view showing one embodiment of a connection circuit board.

FIG. 6 is a perspective view showing the relationship between the connection circuit board and the recording head main body;

FIG. 7 is an explanatory view showing a connection process of the connection circuit board.

FIG. 8 is an explanatory diagram showing a connection process of the connection circuit board.

FIG. 9 is an enlarged view showing a connection state between the connection circuit board and the piezoelectric vibrator.

FIG. 10 is a cross-sectional view showing a structure when a connection circuit board having a conductive pattern formed on one surface is used.

FIG. 11 is an explanatory view showing another embodiment of the connection circuit board of the present invention.

FIG. 12 is a diagram showing a connection state by the connection circuit board according to the first embodiment;

FIG. 13 is a cross-sectional view illustrating an example of a conventional recording head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle plate 2 Nozzle opening 3 Spacer 6 Vibrating plate forming member 7 Piezoelectric vibrator 8 Fixed substrate 9 Vibrator unit 11 Drive electrode 12 Common electrode 14 Drive external electrode 15 Common external electrode 20 Base 30 Connection circuit board 34 Circuit board 38 Ink supply means 48, 49 Conductive pattern T Welding means

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 2/045 B41J 2/055 B41J 2/01

Claims (5)

(57) [Claims] 1. A common external electrode for alternately stacking piezoelectric vibrating substances and electrodes and connecting one electrode as a parallel electrode , and a driving external electrode for connecting the other electrode as a parallel electrode.
And the piezoelectric vibrator, the driving and the piezoelectric vibrating unit configured to end the external electrodes are formed by fixing the fixing plate to the rear end, the piezoelectric in contact with the tip of the piezoelectric vibrator An ink flow path forming member for generating ink droplets by vibrating the vibrator, a base for accommodating the piezoelectric vibration unit and fixing the ink flow path forming member on one end side , and an arrangement pitch of the piezoelectric vibrators. comprising a connection circuit board conductive pattern is formed, the Te, the conductive pattern is driven outside of the piezoelectric vibrator
The connection circuit board is formed so as to form a conductive relationship with an electrode.
An ink jet recording head fixed to the other end of the base ; 2. The ink jet recording head according to claim 1, wherein said drive external electrode is directly connected to an end face thereof and a conductive pattern of a connection circuit board by welding. 3. The ink jet recording head according to claim 1, wherein said connection circuit board is formed of a flexible film. Wherein said the connection circuit board be formed the degree of window exposing the end face of the piezoelectric vibrator, the drive
It has a dynamic external electrode and the conductive pattern is connected by a thin wire
The ink jet recording head according to claim 1 . 5. The ink jet recording head according to claim 4, wherein said connection circuit board is formed of a hard material.