JP2003011374A - Electrostatic ink-jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic ink-jet head having a high leakage resistance, which can be produced easily. SOLUTION: A part of an anisotropic conductive film 18 jutting from a facing part 141 of a wiring conductor 14 in the electrode 13 longitudinal direction (the vertical direction in the figure) prevents leakage with respect to an electrode 13 adjacent to the electrode 13 to be connected with the wiring conductor 14 by forming an insulator between the wiring conductor 14 and the electrode 13 adjacent to the electrode 13 to be connected therewith.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a plurality of electrodes arrayed at a predetermined interval on a flat surface of a head body and a thin plate-shaped wiring conductor for supplying electric power to each electrode. The present invention relates to an electrostatic ink jet head in which a flat cable arranged in an array is connected to each other at its ends.

[0002]

2. Description of the Related Art In an electrostatic ink jet head 10, as shown in FIG. 6, a plurality of ink ejecting portions 12 are formed on an end surface of a plate-shaped head body 11 at a fine pitch (for example, 80 μm).
And a fine width (for example, 40 μm) that extends to the ink ejection portion 12 on the flat surface portion of the head main body 11 thereof.
m), the plurality of electrodes 13 are formed with a fine pitch (for example, the space between adjacent electrodes 13 is 40 μm).

The flat surface of the head body 11 has
An end portion of a power feeding wiring body 15 including a plurality of wiring conductors 14 and formed of a flat cable is arranged.
Each wiring conductor 14 of No. 5 is connected to the corresponding electrode 13 via a wire 16 by a connecting means such as wire bonding, and ink is applied to a space formed between the opposing cover body (not shown). It is supposed to be filled.

In the electrostatic ink jet head 10 having the above-mentioned structure, the drive signal supply portion is connected to the power supply wiring body 1.
A pulsed driving voltage is applied to the electrode 13 via 5,
When this drive voltage is applied to the ink ejecting unit 12 via the electrode 13, the ink ejecting unit 12 ejects the ink toward the recording paper disposed on the counter electrode having a potential difference between the drive voltage and the ink ejecting unit 12. Will be discharged.

However, in the electrostatic ink jet head configured as described above, the space between the electrodes 13 formed in the head body 11 is extremely narrow, for example, 40 μm, and therefore the mounting position of the power supply wiring body 15 is slightly small. However, if the wiring conductors 14 deviate in the left-right direction (arrangement direction of the ink ejection portions 12), the wiring conductors 14 are extremely close to the electrodes 13 adjacent to the electrodes 13 to be connected.

As described above, when the wiring conductor 14 is close to the electrode 13 adjacent to the electrode 13 to be connected, a certain wiring conductor 14 to which a driving voltage is applied and the wiring conductor 14 are provided.
There is a risk that a leak will occur between the electrode 13 to be connected to the electrode 13 and the electrode 13 adjacent to the electrode 13 and ink may be ejected from the ink ejection portion 12 corresponding to the electrode 13 adjacent thereto.
Conventionally, in order to suppress such malfunction, the insulating film 17
Was coated on the connecting portion between the electrode 13 including the wire 16 and the wiring conductor 14.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The above power supply wiring body 1
The work of connecting each wiring conductor 14 of No. 5 to the corresponding electrode 13 by a connecting means such as wire bonding via the wire 16 and the work of covering the insulating film 17 are the electrode 13 of the head body 11 and the power supply wiring body. This is one of the factors that reduce the productivity of the work of connecting the wiring conductors 14 to the wiring conductors 15.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrostatic ink jet head having high leak resistance while being easy to manufacture.

[0009]

According to another aspect of the present invention, there is provided an electrostatic ink jet head having a plurality of electrodes arranged at predetermined intervals on a flat surface of a head body, and a thin plate shape for supplying electric power to each electrode. In the electrostatic ink jet head in which the wiring conductors of the above are connected to each other at the ends thereof and the flat cables arranged in an array corresponding to the spacing, the flat portion of the head main body and the surface of the flat cable are The anisotropic conductive film for thermocompression bonding interposed between the electrodes and the wiring conductor at least in a region wider than the facing portion of the electrode and the wiring conductor has conductivity only in the facing portion of the electrode and the wiring conductor. It is characterized in that an electrode is connected to the wiring conductor.

According to the above structure, since the end portions of the electrodes and the wiring conductors are connected by thermocompression bonding, the productivity is improved. Further, the anisotropic conductive film for thermocompression bonding interposed between the flat portion of the head main body and the surface of the flat cable in a region wider than at least the facing portion of the electrode and the wiring conductor is used for forming the electrode and the wiring conductor. Since only the facing portion has conductivity and the electrode and the wiring conductor are connected to each other, the anisotropic conductive film other than the facing portion is melted and then solidified around the facing portion. Therefore, the anisotropic conductive film, which is the insulator in this portion, prevents leakage between the wiring conductor and the electrode adjacent to the electrode to be connected, even if there is some displacement. The work of covering the insulating film is unnecessary, and the productivity can be improved.

In the electrostatic ink jet head according to the present invention, the dielectric breakdown voltage of the anisotropic conductive film is 12.5K.
It is characterized by being V / mm or more. According to the above structure, the dielectric breakdown voltage of the anisotropic conductive film is 12.5 KV.
/ Mm or more, leakage between the wiring conductor and the electrode adjacent to the electrode to be connected is reliably prevented.

An electrostatic ink jet head according to a third aspect of the invention is characterized in that the diameter of the conductive particles dispersed in the anisotropic conductive film is 10 μm or less. According to the above configuration, since the conductive particles dispersed in the anisotropic conductive film have a diameter of 10 μm or less, melting / heating when the anisotropic conductive film is thermocompression-bonded in a portion other than the facing portion. With the solidification, the conductive particles are not bonded to each other to have conductivity, and leakage between the wiring conductor and the electrode adjacent to the electrode to be connected is reliably prevented.

An electrostatic ink jet head according to a fourth aspect of the invention is characterized in that the conductive particles dispersed in the anisotropic conductive film are made of metal. According to the above configuration, since the conductive particles dispersed in the anisotropic conductive film are made of metal, it is possible to reduce the electric resistance between the electrode and the wiring conductor in the facing portion, and to impart to the electrode. The voltage that can be applied can be increased, and the ink ejection response can be improved.

[0014]

1 is a conceptual diagram of an anisotropic conductive film 18 applied to the present invention. The anisotropic conductive film 18 is configured by dispersing conductive particles 182 having conductivity in a binder resin 181 having an insulating property and mixing them. The binder resin 181 is, for example, an epoxy resin (E
P), and its dielectric breakdown voltage is, for example, 14.9.
KV / mm. The conductive particles 182 are, for example, nickel-made substantially spherical particles plated with gold, and the diameter thereof is, for example, 5 μm. Also,
The thickness of the anisotropic conductive film 18 is 25 μm, for example. The dielectric breakdown voltage of the anisotropic conductive film 18 is about the same as the dielectric breakdown voltage of the binder resin 181 (here, 14.9K).
V / mm).

FIG. 2 is an explanatory view of a thermocompression bonding process using the anisotropic conductive film 18 applied to the present invention.
3 is a sectional view in the width direction of FIG. (A) is an anisotropic conductive film 1
8 and the power supply wiring body 15 are aligned with each other, (b) shows a state where provisional pressure bonding and main pressure bonding are performed using the thermocompression bonding apparatus 70, and (c) shows thermocompression bonding. Shows the state after completion. First, as shown in (a), each wiring conductor 14 of the power supply wiring body 15 is aligned with a position facing the electrode 13 of the head body 11. Then, the anisotropic conductive film 18 is inserted between the electrode 13 and the wiring conductor 14.

Next, as shown in (b), the head main body 11 and the power supply wiring body 15 in which the anisotropic conductive film 18 is sandwiched are set in the thermocompression bonding apparatus 70. Thermocompression bonding device 70
Is a bed (not shown) that supports the head body 11 from below, a flat plate-shaped crimping portion 72 that uniformly presses and heats the head body 11 and the power supply wiring body 15 in the vertical direction,
The screw 73 for pressing down the crimping portion 72 and the crimping portion 7
2 and a heating unit 71 for applying heat.

When the pressing screw 73 is tightened, the pressure applied by the crimping portion 72 to the head body 11 and the power supply wiring body 15 can be increased, and when the pressing screw 73 is loosened, the crimping portion 72 is loosened. Is the head body 11
It is possible to reduce the pressure for pressing down the power supply wiring body 15. Further, the temperature of thermocompression bonding can be changed by changing the amount of heat applied from the heating unit 71 to the pressure bonding unit 72.

Then, the head main body 11 and the power supply wiring body 15 in which the anisotropic conductive film 18 set in the thermocompression bonding apparatus 70 is sandwiched are temporarily pressure-bonded so as not to be displaced during the main pressure-bonding. The condition of temporary pressure bonding is, for example, a pressure of 3 Kgf.
/ Cm ² , temperature is 60 ° C., time is 5 sec
Is. Next, the head body 11 and the power supply wiring body 15 that have been temporarily pressure-bonded are finally pressure-bonded. The conditions for the main pressure bonding are, for example, a pressure of 40 Kgf / cm ² and a temperature of 180 ° C.
And the time is 20 sec.

By the main pressure bonding, the binder resin 181 of the anisotropic conductive film 18 is melted and pressure is applied in the vertical direction, so that the power supply wiring body 15 approaches the head main body 11 in the vertical direction and the electrode 13 is formed. The conductive particles 182 are sandwiched between the wiring conductor 14 and the wiring conductor 14 and stop in a state where they are in contact with each other.

As a result, as shown in FIG.
And the conductive particles 182 are in contact with each other, and the conductive particles 182 and the wiring conductor 14 are in contact with each other, so that the electrode 13 and the wiring conductor 14 are in a conductive state. On the other hand, in a portion other than between the electrode 13 and the wiring conductor 14, the anisotropic conductive film 18 is
Since the conductive particles 182 are dispersed in the binder resin 181, they are electrically insulated. Further, since the binder resin 181 of the anisotropic conductive film 18 is melted and pressure is applied in the vertical direction, the head body 11 and the power supply wiring body 15 are mechanically pressure-bonded by the anisotropic conductive film 18. It

FIG. 3 is an explanatory view of thermocompression bonding using the anisotropic conductive film 18 of the present invention, and is a longitudinal sectional view of the electrode 13 near the thermocompression bonding portion. (A) is an anisotropic conductive film 18
2B shows a state in which the power supply wiring body 15 and the power supply wiring body 15 are aligned, and FIG. 6B shows a state in which the thermocompression bonding apparatus 70 is used for temporary pressure bonding.

As shown in (a), the anisotropic conductive film 18 is formed.
Has an area larger than the areas of the facing portions 131 and 141 where the electrode 13 and the wiring conductor 14 directly face each other, and is set in a state of being sandwiched at a position that covers the facing portion 141 of the wiring conductor 14. . The anisotropic conductive film 18 protrudes from the facing portion 141 of the wiring conductor 14 in the longitudinal direction of the electrode 13 (vertical direction in the drawing) by, for example, 1 mm. The facing portion 141 of the wiring conductor 14 is assumed to have the coating removed in advance. As shown in (b), heat and pressure are applied in the direction of the arrow in the figure (left and right direction in the figure) to perform temporary pressure bonding, whereby the anisotropic conductive film 18 and the power supply wiring are attached to the head body 11. The position with the body 15 is fixed. In addition,
The temperature of the temporary pressure bonding is the binder resin 18 of the anisotropic conductive film 18.
Since the pressure is set to be equal to or lower than the melting point of 1 and the pressure for temporary pressure bonding is set to a pressure small enough to fix the above position, the anisotropic conductive film 18 is not largely deformed by the temporary pressure bonding. .

FIG. 4 is a cross-sectional view and a plan view in the longitudinal direction of the electrode 13 near the thermocompression bonding portion after the thermocompression bonding (main compression bonding) using the anisotropic conductive film 18 of the present invention is completed. (A) is
FIG. 6B is a cross-sectional view of the electrode 13 in the longitudinal direction, and FIG. 6B is a plan view when the wiring conductor 14 is displaced from the electrode 13 in the width direction of the electrode 13 by, for example, 20 μm. Opposing portions 131 and 141 in which the electrode 13 and the wiring conductor 14 directly face each other
In the region 185 (referred to as a conductive region) sandwiched between the two, since the electrode 13 and the conductive particle 182 are in contact with each other and the conductive particle 182 and the wiring conductor 14 are in contact with each other, as described with reference to FIG. Electrically, the electrode 13 and the wiring conductor 14 are in a conductive state.

On the other hand, in a region (referred to as an insulating region) other than the region sandwiched between the facing portions 131 and 141 where the electrode 13 and the wiring conductor 14 directly face each other, the anisotropic conductive film 18 is contained in the binder resin 181. Since the conductive particles 182 are dispersed, they are electrically insulated. In particular, the anisotropic conductive film 18 in a portion protruding from the facing portion 141 of the wiring conductor 14 in the longitudinal direction of the electrode 13 (vertical direction in the drawing) is
By forming the insulating region 186 between each wiring conductor 14 and the electrode 13 adjacent to the electrode 13 to be connected, leakage between each wiring conductor 14 and the electrode 13 adjacent to the electrode 13 to be connected is prevented. To be done.

The reason why the leakage is prevented will be described more specifically. The voltage applied to the electrode 13 during printing is 200V here. In addition, since the space between the adjacent electrodes 13 is 40 μm and the wiring conductor 14 is displaced from the electrodes 13 by 20 μm in the width direction of the electrodes 13, the wiring conductors 14 adjacent to the electrodes 13 to be connected to each wiring conductor 14 are connected. The minimum value of the distance from the electrode 13 is 20 μm. Therefore, each wiring conductor 1
The maximum value of the electric field applied between the electrode 4 and the electrode 13 adjacent to the electrode 13 to be connected is 10 KV / mm (200 V / 20
μm). On the other hand, since the dielectric breakdown voltage of the anisotropic conductive film 18 is about 14.9 KV / mm, no leak occurs.

The diameter of the conductive particles 182 is 5 μm, which is smaller than the minimum value (= 20 μm) between the wiring conductors 14 and the electrode 13 adjacent to the electrode 13 to be connected. Conductive particles 18 in anisotropic conductive film 18 between conductor 14 and electrode 13 adjacent to electrode 13 to be connected
2 does not cause a leak. Furthermore, since the conductive particles 182 are nickel-made substantially spherical particles plated with gold, the electric resistance of the conductive region is almost negligible, and the electric resistance between the electrodes and the wiring conductors in the facing portion is small. The electrical resistance can be reduced, the voltage that can be applied to the electrodes can be increased, and the ink ejection response can be improved.

FIG. 5 is a diagram for explaining an example of the printing operation of the electrostatic ink jet head 10 configured as described above. That is, the electrostatic ink jet head 10 is arranged so that the ink ejecting unit 12 side faces the rotating drum 60 that is a counter electrode held at a negative potential, for example.

In this state, a pulsed drive voltage (for example, 200 V) having a positive potential is applied from the drive signal supply section 62 to the electrode 13 via the flat cable 15 corresponding to the image data to be printed. As a result, a pulsed driving voltage having a positive potential is supplied to the corresponding ink ejecting unit 12, and the coloring material particles 64 in the ink liquid charged positively (+).
Is attracted to the rotating drum 60 side and adheres to the recording paper (recording medium) 66 arranged on the peripheral surface of the rotating drum 60, whereby printing for one line is performed.

When the printing for one line is completed, the rotary drum 60 rotates for the next one line, and then a pulsed driving voltage having a positive potential is supplied to the predetermined ink ejecting section 12 to carry out the next step. Printing for one line is performed. By repeating these operations, the predetermined printing operation is completed. In addition, when performing color printing, at least three electrostatic inkjet heads 10 are arranged in a state of being superposed on each other. As a result, the color material particles 64 corresponding to the respective color inks adhere to the recording paper 66 from the predetermined ink ejecting portions 12 of the respective electrostatic ink jet heads 10 corresponding to the color image data, thereby performing color printing.

The present invention can take the following forms. (A) In the present embodiment, the case where the binder resin 181 of the anisotropic conductive film 18 is an epoxy resin has been described, but another type of resin having a large dielectric breakdown voltage may be used. (B) In this embodiment, the case where the conductive particles 182 of the anisotropic conductive film 18 are nickel-made substantially spherical particles plated with gold is described. It may be made of metal or conductive resin. (C) In the present embodiment, the case where the conductive particles 182 of the anisotropic conductive film 18 have a diameter of 5 μm has been described, but the size may be sufficiently smaller than the space between the adjacent electrodes 13. Good.

[0031]

According to the first aspect of the invention, the productivity is improved because the ends of the electrodes and the wiring conductors are connected by thermocompression bonding. Further, the anisotropic conductive film for thermocompression bonding interposed between the flat portion of the head main body and the surface of the flat cable in a region wider than at least the facing portion of the electrode and the wiring conductor is used for forming the electrode and the wiring conductor. Since only the facing portion has conductivity and the electrode and the wiring conductor are connected to each other, the anisotropic conductive film other than the facing portion is melted and then solidified around the facing portion. Therefore, the anisotropic conductive film, which is the insulator in this portion, prevents leakage between the wiring conductor and the electrode adjacent to the electrode to be connected, even if there is some displacement. The work of covering the insulating film is unnecessary, and the productivity can be improved.

According to the second aspect of the invention, since the dielectric breakdown voltage of the anisotropic conductive film is 12.5 KV / mm or more, it is possible to connect the wiring conductor to the electrode adjacent to the electrode to be connected. The leak can be surely prevented.

According to the third aspect of the invention, since the diameter of the conductive particles dispersed in the anisotropic conductive film is 10 μm or less, the anisotropic conductive film is heated at a portion other than the facing portion. The conductive particles do not combine to have conductivity due to melting and solidification during pressure bonding, and leakage between the wiring conductor and the electrode adjacent to the electrode to be connected can be reliably prevented.

According to the invention as set forth in claim 4, since the conductive particles dispersed in the anisotropic conductive film are made of metal,
It is possible to reduce the electric resistance between the electrode and the wiring conductor in the facing portion, increase the voltage that can be applied to the electrode, and improve the ink ejection response.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an anisotropic conductive film applied to the present invention.

FIG. 2 is an explanatory diagram of a thermocompression bonding process using an anisotropic conductive film applied to the present invention. (A) shows a state in which the anisotropic conductive film and the power feeding wiring body are aligned with each other,
(B) shows a state in which temporary pressure bonding and main pressure bonding are performed using a thermocompression bonding device, and (c) shows a state after the thermocompression bonding is completed.

FIG. 3 is an explanatory diagram of thermocompression bonding using the anisotropic conductive film of the present invention.

FIG. 4 is a cross-sectional view and a plan view in the electrode longitudinal direction near the thermocompression bonding portion after thermocompression bonding using the anisotropic conductive film of the present invention is completed.

FIG. 5 is a diagram for explaining an example of a printing operation of the electrostatic inkjet head.

FIG. 6 is a perspective view of a conventional electrostatic inkjet head.

[Explanation of symbols]

10 Electrostatic inkjet head 11 head body 12 Ink ejection section 13 electrodes 14 wiring conductor 15 Power supply wiring (flat cable) 17 Insulation film 18 Anisotropic conductive film 181 binder resin 182 conductive particles 185 Conductive area 186 Insulator area

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Fumihiko Nakamura             No. 1 at 579 Umehara, Wakayama City, Wakayama Prefecture             Inside Ritsu Koki Co., Ltd. (72) Inventor Yuji Yamamoto             No. 1 at 579 Umehara, Wakayama City, Wakayama Prefecture             Inside Ritsu Koki Co., Ltd. F-term (reference) 2C057 AG84 BD07

Claims (4)

[Claims] 1. A flat plate in which a plurality of electrodes arrayed at a predetermined interval on a flat surface of the head body and thin plate-shaped wiring conductors for supplying electric power to each electrode are arrayed on the surface in conformity with the interval. In an electrostatic ink jet head in which a cable and a cable are connected to each other at their ends, the electrostatic inkjet head is wider than a flat portion of the head main body and a surface of the flat cable and is at least larger than a portion where the electrode and the wiring conductor face each other. An electrostatic ink jet head in which an anisotropic conductive film for thermocompression bonding interposed in a region has conductivity only in a portion where the electrode and the wiring conductor face each other and connects the electrode and the wiring conductor. 2. The dielectric breakdown voltage of the anisotropic conductive film is 1.
2. It is at least 2.5 KV / mm.
The electrostatic ink jet head described in 1. 3. The electrostatic ink jet head according to claim 1, wherein the conductive particles dispersed in the anisotropic conductive film have a diameter of 10 μm or less. 4. The electrostatic ink jet head according to claim 1, wherein the conductive particles dispersed in the anisotropic conductive film are made of metal.