JPH09286103A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the erosion of an electrode part, the deterioration of the characteristics of a piezoelectric vibrator and the baking of cover coat caused by overheating at the time of the soldering with a flexible cable. SOLUTION: An ink jet recording head is equipped with the pressure generating chambers communicating with nozzle orifices and common ink chambers and sealed on one surface side thereof by a lid member, piezoelectric vibrators formed on the lid member corresponding to the pressure generating chambers and drive electrodes and common electrodes supplying drive signals to the piezoelectric vibrators and the drive electrodes and the common electrodes are connected to an external drive means through flexible cables 30. In this case, the connection parts 68 of the conductive patterns 63-65 soldered to the common electrodes of the flexible cables 30 are divided into a plurality of parts to reduce heat capacity herein.

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 in which a nozzle plate, a flow path forming member, and a vibrating plate are laminated, and a flexural vibration mode piezoelectric vibrator is attached to the surface of the vibrating plate. The present invention relates to the structure of a flexible cable that supplies a drive signal to a piezoelectric vibrator.

[0002]

2. Description of the Related Art An ink jet recording head in which a nozzle plate, a flow path forming member, and a vibrating plate are laminated and a flexural vibration mode piezoelectric vibrator is attached to the surface of the vibrating plate is composed of most of these members made of ceramic. Because
By stacking each member in the state of a green sheet and fixing it by firing it without using an adhesive, there is an advantage that the joining process is unnecessary and the manufacturing process can be simplified. There is. In such a recording head, a flexible cable is connected to a connection terminal extended from a drive electrode of a piezoelectric vibrator by soldering, a drive signal is received from an external drive circuit, and an ink droplet is ejected in accordance with print data.

[0003]

However, in a recording head in which a large number of nozzles are formed in order to improve the printing quality and the printing speed, the number of drive electrodes becomes extremely large, which is accompanied by this. The soldering area of each drive electrode becomes smaller, and the solder used for connection with the flexible cable overflows from the connection terminal and flows out to the drive electrode, and the flexible metal, such as gold (Au), that constitutes the drive electrode. ) Etc. film is eroded by the molten solder, resulting in a “gold erosion phenomenon”. Although such a phenomenon of gold erosion can be tolerated to some extent, when the temperature locally rises, the erosion further progresses and the conductive relationship between the drive electrode and the connection terminal is broken, so that ink droplets are There is a problem that it becomes impossible to discharge. In addition, when the temperature rises, the cover coat forming the surface layer of the flexible cable burns, and when the temperature rises further, even the drive electrode side to be soldered overheats and the PZT.
Therefore, there arises a problem that the characteristics of the piezoelectric vibrator constituted by the above are affected and the print quality varies.

Particularly, these problems are caused in that the connection portion on the recording head side and the drive circuit board side of the connection pattern with the common electrode, one of which is formed as a wide pattern, has an area proportional to the width of the conductive pattern. Since it becomes large, it takes time to rise to the solder melting temperature, and the connection portion with the drive electrode, which is narrower than this, is overheated.

The present invention has been made in view of the above problems, and an object of the present invention is to cause corrosion of the drive electrode due to soldering of the drive electrode and the flexible cable, and piezoelectric due to overheating. An object of the present invention is to provide an ink jet recording head equipped with a flexible cable capable of eliminating a change in the characteristics of a vibrator and, further, a burn-in of a cover coat layer.

[0006]

In order to solve such a problem, in the present invention, a pressure generating chamber communicating with an ink chamber common to a nozzle opening and having one surface sealed with a lid member, A piezoelectric vibrator array formed on the surface of the lid member so as to correspond to the pressure generating chambers, a drive electrode that supplies a drive signal to the piezoelectric vibrator, and a common electrode, and the drive electrode. In an ink jet recording head in which a common electrode is connected to an external drive unit via a flexible cable, a connecting portion of a conductive pattern to be soldered to the common electrode of the flexible cable is divided into a plurality of parts. Lower the heat capacity to enable soldering without overheating.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention will be described below with reference to illustrated embodiments. FIG. 1 is a view showing an embodiment of a recording head of the present invention as a sectional structure in the vicinity of one pressure generating chamber. In the drawing, reference numeral 2 is a first lid member having a thickness of 1
It is composed of a thin plate of zirconia of about 0 μm, a common electrode 4 serving as one pole is formed on its surface, and a PZT or the like is formed on the surface so as to face pressure generating chambers 3, 3 ′, 3, 3 ′ described later. The piezoelectric vibrators 5 and 5 ′ are fixed, and drive electrodes 6 and 6 ′ made of a relatively flexible metal layer such as gold are formed on the surface of the piezoelectric vibrators 5 and 5 ′. Auxiliary electrodes 21 and 21 ′, which electrically connect to 7 and 7 ′ and are electrically independent of each other, are driving electrodes 6,
It is formed at a position facing 6 '.

Reference numerals 7 and 7 are connection terminals formed on the sides of the first lid member 2, and are auxiliary electrodes 21 and 2 as shown in FIG.
When the drive electrodes 6 and 6'are formed through 1 ', a part of the drive electrodes 6 and 6'is drawn out to this point and is electrically connected to the drive electrodes 6 and 6'with a gap.

Reference numeral 8 denotes a spacer, which is formed by forming a through hole in a ceramic plate of zirconia (ZrO2) or the like having a thickness suitable for forming the pressure generating chambers 3 and 3 ', for example, 150 μm, which will be described later. Both surfaces are sealed by the second lid member 9 and the first lid member 2 to form the pressure generating chambers 3 and 3'described above.

Reference numeral 9 is a second lid member, which is also described later on the ceramic plate of zirconia or the like, and ink supply ports 13 and 13 '.
And communication holes 10, 10 'for connecting the pressure generating chambers 3 and 3'
And the nozzle communication holes 11 and 11 ′ that connect the nozzle openings 18 and 18 ′ and the other ends of the pressure generating chambers 3 and 3 ′, respectively, and are fixed to the other surface of the spacer 8.

These members 2, 8 and 9 are assembled in the actuator unit 1 without using an adhesive by molding a clay-like ceramic material into a predetermined shape and stacking and firing it. .

Reference numeral 12 denotes an ink supply port forming substrate which also serves as a fixed substrate of the actuator unit 1 and has a common ink chamber 1 which will be described later on one end side of the pressure generating chambers 3 and 3 '.
Ink supply ports 13 and 13 'for connecting the pressure generating chambers 3 and 3'to the pressure generating chambers 3 and 3'are provided, and nozzles for connecting to the nozzle openings 18 and 18' are provided on the other end side of the pressure generating chambers 3 and 3 '. Communication holes 14 and 14 'are provided.

Reference numeral 19 denotes a common ink chamber forming substrate, which is connected to the common ink chambers 15 and 15 'for receiving the inflow of ink from an ink tank (not shown) and the nozzle communication holes 16 and 16 for connecting the nozzle openings 18 and 18'. ′ Is provided, and the other surface is sealed by the nozzle plate 17 to form common ink chambers 15 and 15 ′.

Reference numeral 17 denotes the above-mentioned nozzle plate, which is the nozzle communication holes 11, 14, 16 and the nozzle communication holes 11 ', 1'.
Nozzle openings 18, 18 'are formed so as to communicate with the pressure generating chambers 3, 3'via 4', 16 '.

The ink supply port forming substrate 12, the common ink chamber forming substrate 19, and the nozzle plate 17 are fixed to each other with an adhesive layer such as a heat-welding film or an adhesive, and are assembled in the flow path unit 20. .

A recording head is constructed by fixing the flow path unit 20 and the actuator unit 1 described above with a heat-welding film, an adhesive or the like.

Reference numeral 30 denotes a flexible cable, as shown in FIG. 2, a rolled copper foil 32 is laminated on one surface of a base material 31 made of a heat resistant flexible film such as polyimide, and the copper foil 32 is connected. An insulating layer 33 is formed in a region not facing the terminal 21, while a copper plating layer having good solder wettability is formed in a region facing the connecting terminals 7 and 7 ′ to form a connecting portion 34. Has been done.

FIG. 3 shows the flexible cable 3 described above.
1 shows an example of a connection portion and a conductive pattern formed at 0. Here, in order to clarify the configuration, the insulating layer 33 is removed and the conductive pattern is exposed. In this embodiment, a flexible cable used for ejecting four color inks of black ink, yellow ink, cyan ink, and magenta ink from one recording head will be described as an example. That is, since the black ink prints characters and the like at a high resolution, the nozzle openings in the two rows are arranged with a half pitch offset, and the nozzles that eject the yellow ink, cyan ink, and magenta ink have a black pitch. The nozzles are arranged so as to have a pitch twice as large as the pitch of the nozzles for ejecting ink, and to be arranged on the nozzle openings of two rows for ejecting black ink so as to be positioned on the same line as the nozzles of one row.

In the figure, an area indicated by reference numeral 40 is a connection area with the recording head, and an area indicated by reference numeral 41 is a connection area with a drive circuit board, and a lead area 42 is provided between these areas.
Are formed. In the lead region 42, the conductive pattern 60, 61, 62 connecting the connecting portion 34 and the connecting portion 50 at both ends for supplying a drive signal is located so as to be located farther than the conductive patterns 60-62. Wide conductive patterns 63, 64, and 65 are formed on.

In this embodiment, since the recording heads for ejecting inks of a plurality of colors are connected as described above, the slits 43 are provided between the adjoining portions so as to correspond to the array form of the piezoelectric vibrators for ejecting the inks of the respective colors. , 43 are provided, and the connecting portion 3
It is configured so that a short circuit does not occur between the four. Further, a concave portion 44 is formed on the lead region 42 side from the connection terminals 7 and 7 ′ for connection with the recording head, and a common electrode connection portion 45 connected to the common electrodes 4 and 4 is provided immediately outside the drive electrodes 6 and 6 ′. Four
6 are formed.

On the other hand, in the region 41 where the connection with the drive circuit board is made, on both sides thereof, similarly to the connection portion 34, the connection portions 50, 50 for supplying drive signals, which are made of a copper plating layer, are provided.
50 are formed in groups for each row of nozzle openings.

Then, as shown in FIG. 4, a patterning pattern 70 for positioning is formed in one connection portion 45 connected to the common electrode, and the other connection portion 46 connected to the common electrode is provided in the central portion. The slit 71 is provided and is divided into two connecting portions 46a, 46a so as to be bifurcated.

On the other hand, the area 4 for connecting to the drive circuit board
Among the conductive patterns with the lower electrode in No. 1, the conductive pattern 63 has a pattern cutout 72, and the conductive pattern 64 is provided with a slit 73 as shown in FIG. 67a, 67a, and a pattern cutout 74 is formed in the vicinity thereof.

As shown in FIG. 6, a plurality of conductive patterns 68 with the lower electrode for connection with the drive circuit board are provided, and in this embodiment, four areas 68a, 68a, 68a, 68a.
And a pattern cutout 75 is formed in the vicinity thereof. Incidentally, reference numeral 76 in the drawing indicates a pattern removal for positioning.

When the area 40 of the flexible cable is aligned with the recording head through the through hole 70 with the solder paste applied to the connecting terminal 7 or the connecting portion 34 thus constructed, the flexible cable 30 is connected. The parts 34, 45, 46 coincide with the connection terminals 7, 7 ′ of the actuator unit 1.

In this state, when the surface of the base material 31 of the flexible cable 30 is heated to a temperature sufficient to melt the solder paste, the connecting portions 34, 34 with the drive electrodes,
The size of each is uniform and the width is narrow,
The solder in this area melts immediately. On the other hand, the connection portion 34
Even in the connecting portions 45 and 46 with the common electrode 4 which are remarkably wider than those in FIG. 1, since the heating required area is reduced by the pattern removal 70 and the slit 71, the soldering is performed in a solid state. Since the heat capacity is smaller than that of the conventional soldering, the temperature rises to a temperature sufficient to melt the solder in a short time, and the soldering is completed without overheating the connecting portion 34 with the drive electrode.

In this embodiment, since a relatively long recess 44 is formed near the connecting portion 45 of the conductive pattern 63 connected to the connecting portion 45, the thermal resistance of the region along the recess 44 is large. In comparison with the case where the slit 80 is simply provided as shown in FIG. 7, heat dissipation during soldering is prevented as much as possible, and unnecessary overheating of the connection portion 34 is prevented. There is.

Further, as shown in FIG. 8, in the conductive pattern 65 connected to the connecting portion 45 with the common electrode, the connecting portion 45 is provided.
By forming a relatively elongated rectangular pattern cutout 69 in the vicinity of, the case where at least one nozzle opening of a recording head having a plurality of nozzle opening rows is not used, that is, four nozzle opening rows are formed. If one printhead is built in, and three of these are used to eject ink of three colors, cyan, magenta, and yellow, and a different printhead is used for black ink, , The thermal resistance of the area along the pattern removal 69 increases,
Dispersion during soldering can be prevented as much as possible, and soldering can be completed promptly without the need for heating the connection portion 34 for a long time, and overheating of the surroundings can be prevented.

Further, even when it is not necessary to solder a part of the driving electrode as described above, a dummy conductive pattern is formed in the vicinity of the connecting portion 46 with the common electrode, so that the flexible cable can be formed. Not only can the thinning of the connecting portion 46 be prevented in the manufacturing process, but also the heat distribution at the time of soldering can be made equal to that of the other regions, and uniform soldering can be performed.

On the other hand, also in connection with soldering for connection to the drive circuit board, through holes 72 and slits 67 are also formed in the connecting portions 66, 67, 68 of the wide conductive patterns 63, 64, 65 in the same manner as described above. Is formed or is divided into the narrow connecting portions 68a, 68a, the connecting portion 50 for supplying a signal to the drive electrode does not overheat like the connecting region 40 with the recording head, and can be quickly The temperature rises to the solderable temperature.

The area 41, which has a longer soldering area than the connection area 40 with the recording head, receives a force such as contraction or expansion during soldering, but the slits 67, 67 provided near the central portion It is prevented from being absorbed and causing wrinkles and bending.

In the above-described embodiment, the case where the signal is supplied to one recording head has been described. However, as shown in FIG. 8, the arrangement in which two recording heads are arranged in the paper feeding direction is as shown in FIG. A slit 83 is formed between the connecting areas 81 and 82 of the respective recording heads to the drive electrodes, and the connecting portions 84a and 84a to the lower electrodes are formed therein, thereby forming the connecting area 41 to the drive circuit board. Similarly to the slit 67, the plurality of recording heads can be soldered without causing unnecessary overheating, wrinkles, and bending.

[0033]

As described above, in the present invention,
A pressure generating chamber that communicates with the nozzle opening and a common ink chamber and has one surface sealed with a lid member, a piezoelectric vibrator formed on the surface of the lid member so as to correspond to the pressure generating chamber, and a piezoelectric vibration. In an inkjet recording head, which includes a drive electrode and a common electrode for supplying a drive signal to a child, and the drive electrode and the common electrode are connected to an external drive unit via a flexible cable, the common electrode of the flexible cable is soldered. Since the connection part of the conductive pattern is divided into a plurality of parts, the heat capacity of the connection part connected to the common electrode is reduced, and the temperature can be raised at almost the same speed as the connection part of the drive electrode. By eliminating overheating of the connection portion, it is possible to prevent erosion, variation in characteristics of the piezoelectric vibrator, and seizure of the cover coat.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a structure of an ink jet recording head of the present invention near a pressure generating chamber.

FIG. 2 is an enlarged view showing a structure of a connection terminal formed on a surface of an actuator unit and a connection portion of a flexible cable.

FIG. 3 is a diagram showing an example of a conductive pattern formed on a flexible cable connected to the ink jet recording head.

FIG. 4 is an enlarged view showing a connection area of the flexible cable on the recording head side.

FIG. 5 is an enlarged view showing a connection area on the drive circuit board side of the flexible cable of the above.

FIG. 6 is an enlarged view showing a connection area on the drive circuit board side of the above flexible cable.

FIG. 7 is an enlarged view showing an example of a flexible cable as a comparative example in the vicinity of a connection area of a recording head.

FIG. 8 is an enlarged view showing a connection area on the recording head side of the flexible cable of the present invention.

FIG. 9 is a diagram showing another embodiment of the flexible cable of the present invention.

[Explanation of symbols]

1 Actuator Unit 2 First Lid Member 3, 3'Pressure Generation Chamber 4, 4'Common Electrode 5, 5'Piezoelectric Vibrator 6, 6'Drive Electrode 7, 7'Connection Terminal 18, 18 'Nozzle Opening 20 Flow Path Unit 21 Auxiliary electrode 30 Flexible cable 34 Connection portion with drive electrode 40 Connection area with recording head 41 Connection area with drive circuit board 42 Conductive pattern area 44 Recesses 45, 46 Connection portion with common electrode 47 Dummy conductive pattern 50 Connection part of the conductive pattern connected to the drive electrode on the drive circuit board side 60, 61, 62 Conductive pattern 63, 64, 65 connected to the drive electrode Conductive pattern 67 connected to the common electrode 67 Slit 69 Pattern removal 70 Pattern removal for positioning

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Masayuki Kobayashi 3-3-5 Yamato, Suwa City, Nagano Seiko Epson Corporation

Claims (7)

[Claims] 1. A pressure generating chamber that communicates with a common ink chamber with a nozzle opening and has one surface sealed with a lid member, and a line on the surface of the lid member so as to correspond to the pressure generating chamber. An ink jet type in which a formed array of piezoelectric vibrators, drive electrodes for supplying drive signals to the piezoelectric vibrators and a common electrode are provided, and the drive electrodes and the common electrodes are connected to an external drive means via a flexible cable. In the recording head, an ink jet recording head in which a connecting portion of a conductive pattern to be soldered to the common electrode of the flexible cable is divided into a plurality. 2. The ink jet recording head according to claim 1, wherein a slit is formed in a connection portion of a conductive pattern to be soldered to the common electrode of the flexible cable. 3. The ink jet recording head according to claim 1, wherein the slit is formed in a central portion of a connection region. 4. The ink jet recording head according to claim 1, wherein a patterning hole for positioning is formed at a connection portion of a conductive pattern soldered to the common electrode of the flexible cable. 5. The ink jet recording head according to claim 1, wherein the conductive pattern is narrowed by cutting out the lead pattern side in the vicinity of the connection portion of the conductive pattern soldered to the common electrode of the flexible cable. . 6. The driving of the flexible cable soldered to a drive electrode of the piezoelectric vibrator array when a plurality of the piezoelectric vibrator arrays are provided, and at least one of the piezoelectric vibrator arrays does not participate in ink droplet ejection. The ink jet recording head according to claim 1, wherein a rectangular pattern punch is formed in a lead pattern near a connection portion of a conductive pattern that is soldered to the common electrode that is close to an electrode. 7. The drive of the flexible cable, comprising a plurality of the piezoelectric vibrator rows, wherein at least one of the piezoelectric vibrator rows is soldered to a drive electrode of the piezoelectric vibrator row when at least one row does not participate in ink droplet ejection. 2. A dummy pattern is formed on a lead pattern near a connecting portion of a conductive pattern which is soldered to the common electrode adjacent to the electrode.
3. The ink jet recording head according to item 1.