Liquid ejection head

Abstract

To protect both a flow channel member and a heat radiation member from static electricity using a grounding member.SOLUTION: A head comprises: a flow channel member 10 in which a flow channel is formed with a nozzle at its tip, and constituted of a conductive material; an actuator member 20 having an actuator which imparts energy for discharging liquid from the nozzle, to the liquid in the flow channel; a driver IC 30 which is electrically connected to the actuator, and drives the actuator; a heat radiation member 40 thermally connected to the driver IC 30; and a grounding member 50 which is electrically grounded. The grounding member 50 is electrically connected to the flow channel member 10 via a connection part 53, and electrically connected to the heat radiation member 40 via an extension part 52.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection head including a flow path member, a heat dissipation member, and a grounding member. [Background technology]

[0002] Patent Document 1 discloses a recording head (liquid ejection head) equipped with a head chip (flow path member), a heat dissipation member, and a grounding terminal (grounding member). The heat dissipation member is thermally connected to the drive circuit of the head chip and electrically connected to the grounding terminal. This allows static electricity to be discharged to the ground through the grounding terminal, protecting the drive circuit, even if static electricity is discharged to the heat dissipation member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-223313 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the earth terminal portion (grounding member) is electrically connected to the heat dissipation member but not to the head chip (flow path member). Therefore, although the grounding member can protect the heat dissipation member from static electricity, it cannot protect the flow path member from static electricity.

[0005] An object of the present invention is to provide a liquid ejection head that can protect both the flow path member and the heat dissipation member from static electricity by using a grounding member. [Means for solving the problem]

[0006] The liquid ejection head of the present invention comprises a flow path member made of a conductive material in which a flow path having a nozzle at its tip is formed, an actuator that imparts energy to the liquid in the flow path to eject the liquid from the nozzle, a drive circuit that is electrically connected to the actuator and drives the actuator, a heat dissipation member that is thermally connected to the drive circuit, and a grounding member that is electrically grounded, and is characterized in that the grounding member is electrically connected to both the flow path member and the heat dissipation member. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a plan view of a printer 100 equipped with a head 1 according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of a head unit 1u including three heads 1. [Figure 3] FIG. [Figure 4] FIG. 2 is a perspective view of the head 1 with the holder 90 omitted. [Figure 5] FIG. 5 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. [Figure 7] 2 is a cross-sectional view showing a flow path 10x formed in a flow path member 10. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] First Embodiment First, with reference to FIG. 1, the overall configuration of a printer 100 equipped with a head 1 according to a first embodiment of the present invention will be described.

[0009] The printer 100 includes a head unit 1u including three heads 1, a platen 3, a transport mechanism 4, and a control unit 5.

[0010] The head unit 1u is a line type that is elongated in the paper width direction (a direction perpendicular to the vertical direction) and ejects ink onto paper 9 from nozzles 15 (see FIG. 7) while being fixed in position. Each of the three heads 1 is elongated in the paper width direction and is arranged in a staggered pattern in the paper width direction. A plurality of nozzles 15 (see FIG. 7) are opened on the underside of each head 1. When the driver IC 30 (see FIG. 5) of each head 1 is driven under the control of the control unit 5, ink is selectively ejected from the plurality of nozzles 15 of each head 1.

[0011] The platen 3 is a flat plate member that is disposed below the head unit 1u and extends in a direction perpendicular to the vertical direction.

[0012] The transport mechanism 4 has two pairs of rollers 4a and 4b arranged on either side of the platen 3 in the transport direction (the direction perpendicular to the vertical direction and the paper width direction), and a transport motor (not shown) that rotates the pairs of rollers 4a and 4b. When the transport motor is driven under the control of the control unit 5, the pairs of rollers 4a and 4b rotate while sandwiching the paper 9, and the paper 9 is transported in the transport direction.

[0013] The control unit 5 has a ROM (Read Only Memory), a RAM (Random Access Memory), and an ASIC (Application Specific Integrated Circuit). The ROM stores programs and data for the ASIC to control various operations. The RAM temporarily stores data used by the ASIC when executing a program. The ASIC executes recording processing according to the program stored in the ROM.

[0014] In the recording process, the control unit 5 controls the conveyance motor based on a recording command received from an external device (such as a PC) to carry out a conveyance process in which the paper 9 passes under the heads 1, and controls the driver IC 30 of each head 1 to selectively discharge ink from the multiple nozzles 15 of each head 1. In this way, an image is recorded on the paper 9.

[0015] Next, the configuration of the head unit 1u and each head 1 included in the head unit 1u will be described.

[0016] As shown in FIG. 2, the head unit 1u includes a carriage 1c and three heads 1.

[0017] The carriage 1c holds the three heads 1 and corresponds to the "holding member" of the present invention. The carriage 1c is a rectangular plate-shaped member made of a conductive material such as metal, and is electrically grounded.

[0018] Each of the three heads 1 includes a holder 90 that fits into an opening formed in the carriage 1c, a flow path member 10, an actuator member 20, a driver IC 30, and a heat dissipation member 40 (see Figures 2 to 5) supported by the holder 90, a grounding member 50, and an ink tank (not shown).

[0019] The flow path member 10 and the heat dissipation member 40 are made of a conductive material such as metal, while the holder 90 is made of a non-conductive material such as resin. The flow path member 10 and the heat dissipation member 40 are electrically insulated from the carriage 1c by the holder 90 being interposed between them and the carriage 1c.

[0020] The grounding member 50 is made of stainless steel and is attached to the edge of the holder 90 and fixed to the carriage 1c via screws 61. The screws 61 are made of a conductive material such as metal. The grounding member 50 is electrically connected to the carriage 1c via the screws 61 and is electrically grounded.

[0021] 4 and 5, the flow path member 10 includes a first flow path member 11 and a second flow path member 12. The first flow path member 11 and the second flow path member 12 are both made of a conductive material such as metal (SUS, etc.), but are connected to each other via a non-conductive adhesive such as resin, and are electrically insulated from each other.

[0022] The first flow path member 11 is a rectangular frame-shaped member that houses the second flow path member 12 within the frame and holds the second flow path member 12. The first flow path member 11 has a flow path (not shown) formed therein for ink to flow from an ink tank to the second flow path member 12.

[0023] As shown in FIG. 7, the second flow path member 12 is made up of nine plates 101 to 109. The plates 101 to 109 are stacked in the vertical direction and bonded to one another with an adhesive. Each of the plates 101 to 109 has a through-hole formed therein that forms a flow path 10x. The flow path 10x includes a common flow path 13 common to the multiple nozzles 15 and individual flow paths for each nozzle 15, and is a flow path (a flow path having a nozzle 15 at its tip) that runs from the common flow path 13 to the nozzle 15 via the pressure chamber 14 of each individual flow path. The multiple nozzles 15 are opened on the lower surface of the second flow path member 12.

[0024] 7, the actuator member 20 includes two piezoelectric layers 21 and 22, a plurality of individual electrodes 23, and a common electrode 24. The piezoelectric layers 21 and 22 and the common electrode 24 are provided over the entire upper surface of the second flow path member 12. On the other hand, the individual electrodes 23 are provided for each pressure chamber 14, and overlap the pressure chambers 14 in the vertical direction.

[0025] A sealing member 19 is disposed between the actuator member 20 and the second flow path member 12. The sealing member 19 covers a plurality of pressure chambers 14 formed on the upper surface of the second flow path member 12. The sealing member 19 is made of a material with low ink permeability (stainless steel, etc.), and does not have a portion that functions as an actuator 20x, which will be described later.

[0026] As shown in Fig. 5, a COF (Chip On Film) 25 is disposed on the upper surface of the actuator member 20. The COF 25 has a central portion electrically connected to the individual electrodes 23 and the common electrode 24, and opposite end portions extending upward from both ends of the central portion in the paper width direction. A driver IC 30 is mounted on both end portions of the COF 25. The driver IC 30 is electrically connected to the individual electrodes 23 and the common electrode 24 via the COF 25.

[0027] The driver IC 30 maintains the potential of the common electrode 24 at ground potential while varying the potential of the individual electrode 23 between a predetermined drive potential and ground potential. Specifically, the driver IC 30 generates a drive signal based on a control signal from the control unit 5 and supplies the drive signal to the individual electrode 23. As a result, the potential of the individual electrode 23 varies between the predetermined drive potential and ground potential. At this time, the portion of the piezoelectric layer 21 sandwiched between the individual electrode 23 and the common electrode 24 (the actuator 20x) contracts in the planar direction due to the piezoelectric transverse effect. Accordingly, the portions of the actuator member 20 and the sealing member 19 that vertically overlap the pressure chamber 14 deform convexly toward the pressure chamber 14, thereby reducing the volume of the pressure chamber 14. Pressure is applied to the ink in the pressure chamber 14, causing the ink to be ejected from the nozzle 15. In this way, the actuator 20x applies energy to the ink in the flow channel 10x, causing the ink to be ejected from the nozzle 15. The driver IC 30 drives the actuator 20x as described above and corresponds to the "drive circuit" of the present invention.

[0028] As shown in Fig. 5, the COF 25 is arranged along the lower surface and side surfaces of the support member 70. The support member 70 is made of a non-conductive material such as resin, and as shown in Figs. 4 and 5, supports the heat dissipation member 40 from below. The center of the COF 50 is pressed against the lower surface of the support member 70. Both ends of the COF 50 extend along the side surfaces of the support member 70 and are bent inward at the upper ends of the side surfaces of the support member 70.

[0029] 5, the driver IC 30 is in contact with the lower surface of the heat dissipation member 40 and is thermally connected to the heat dissipation member 40. The driver IC 30 and the heat dissipation member 40 are electrically insulated from each other by the presence of a non-conductive material between them.

[0030] 6, the grounding member 50 has a base 51 that is long in the conveyance direction, an extension 52 provided in the center of the base 51 in the longitudinal direction (conveyance direction), and a pair of connection parts 53 provided at one end and the other end in the longitudinal direction (conveyance direction) of the base 51. One of the pair of connection parts 53 corresponds to the "first connection part" of the present invention, and the other corresponds to the "second connection part" of the present invention.

[0031] 6, a hole 51y for attaching a screw 61 (see FIGS. 2 to 5) is provided in the center of the longitudinal direction of the base 51. The grounding member 50 is fixed to the carriage 1c at the center of the base 51 via the screw 61, and is thereby electrically connected to the carriage 1c and electrically grounded.

[0032] 6, two positioning holes 51x are further provided in the base 51. The two positioning holes 51x are arranged at positions sandwiching the center in the longitudinal direction of the base 51. The grounding member 50 is positioned relative to the holder 90, and ultimately the carriage 1c, by inserting the protrusions 91 of the holder 90 into the positioning holes 51x (see FIG. 3).

[0033] As shown in Fig. 5, the extending portion 52 extends obliquely downward from one end of the base portion 51 in the paper width direction toward the side surface of the heat dissipation member 40. The extending portion 52 is inclined with respect to the side surface of the heat dissipation member 40. As the grounding member 50 is made of stainless steel as described above, the extending portion 52 is flexible and makes point contact with the side surface of the heat dissipation member 40 at its tip 52t. The contact of the extending portion 52 with the heat dissipation member 40 electrically connects the grounding member 50 to the heat dissipation member 40, and electrically grounds the heat dissipation member 40.

[0034] 6, the extending portion 52 has a through-hole 52x formed therein, which is elongated along the direction in which the extending portion 52 extends from the base portion 51. A portion of the extending portion 52 including a tip 52t is rounded.

[0035] As shown in Fig. 6, the pair of connecting portions 53 are each provided with a through-hole 53x for attaching a screw 63 (see Figs. 4 and 5). The screw 63 is made of a conductive material such as metal, has an upper end connected to the connecting portion 53, and a lower end connected to the first flow path member 11, and connects the connecting portion 53 to the first flow path member 11. The grounding member 50 is electrically connected to the first flow path member 11 by fixing the pair of connecting portions 53 to the first flow path member 11 via the screws 63, and electrically grounds the first flow path member 11.

[0036] As described above, the second flow path member 12 is electrically insulated from the first flow path member 11, but is electrically grounded via the conductive ink flowing through the first flow path member 11 and the second flow path member 12.

[0037] As described above, according to this embodiment, the grounding member 50 is electrically connected to the flow path member 10 via the pair of connecting portions 53 and the conductive ink (see FIGS. 4 and 5), and is also electrically connected to the heat dissipation member 40 via the extending portion 52 (see FIG. 5). This allows the grounding member 50 to protect both the flow path member 10 and the heat dissipation member 40 from static electricity.

[0038] The grounding member 50 is in point contact with the heat dissipation member 40 (see FIG. 5). In this case, the contact area between the grounding member 50 and the heat dissipation member 40 can be reduced, and the contact strength between them can be increased. This reduces the electrical resistance between the grounding member 50 and the heat dissipation member 40, making it easier for electricity to flow, and therefore the heat dissipation member 40 can be reliably electrically grounded.

[0039] The portion of the grounding member 50 that comes into point contact with the heat dissipation member 40 (the portion including the tip 52t of the extension portion 52) is rounded (see FIG. 6). In this case, the tip 52t of the rounded portion can come into point contact with the heat dissipation member 40, thereby achieving point contact more effectively.

[0040] In the grounding member 50, the extending portion 52 extending from the base portion 51 toward the heat dissipation member 40 is flexible (see FIG. 6). In this case, even if there is some misalignment between the grounding member 50 and the heat dissipation member 40, point contact between the grounding member 50 and the heat dissipation member 40 can be achieved.

[0041] Through holes 52x are formed in the extending portion 52 (see FIG. 6). In this case, the flexibility of the extending portion 52 can be increased, and the reliability of contact between the grounding member 50 and the heat dissipation member 40 can be improved even if the positions of the grounding member 50 and the heat dissipation member 40 are misaligned.

[0042] The extension 52 is made of stainless steel. Since stainless steel has high elasticity, the flexibility of the extension 52 can be increased.

[0043] The extension portion 52 is inclined with respect to the side surface of the heat dissipation member 40 (the surface including the portion that makes point contact with the tip 52t of the extension portion 52 on the heat dissipation member 40) (see Figure 5).In this case, compared to when the extension portion 52 is perpendicular to the surface, an appropriate contact strength is obtained and the reliability of contact against misalignment between the grounding member 50 and the heat dissipation member 40 can be improved.

[0044] A pair of connecting portions 53 provided at both longitudinal ends of the base 51 are connected to the flow path member 10 (see FIGS. 4 and 5). In this case, the grounding member 50 and the flow path member 10 are electrically connected by the pair of connecting portions 53 provided at both longitudinal ends of the base 51, thereby improving the reliability of the electrical connection therebetween.

[0045] The grounding member 50 is electrically connected to the carriage 1c by being fixed to the carriage 1c at the center of the base 51 (see FIGS. 2 and 3). In this case, by fixing the center of the base 51 to the carriage 1c, the base 51 is fixed in a more balanced manner than when one end of the base 51 is fixed to the carriage 1c, and a stable electrical connection between the carriage 1c and the grounding member 50 can be achieved.

[0046] Two positioning holes 51x are provided at positions sandwiching the center in the longitudinal direction of the base 51 (see FIG. 6). In this case, the carriage 1c and the grounding member 50 can be reliably positioned (see FIGS. 2 and 3).

[0047] Second Embodiment Next, a head according to a second embodiment of the present invention will be described.

[0048] In the first embodiment, only the first flow path member 11 of the flow path member 10 is electrically connected to the grounding member 50 via a screw 63 (the "connecting member" of the present invention) (see Figures 4 and 5), and the second flow path member 12 is electrically grounded via conductive ink flowing through the first flow path member 11 and the second flow path member 12.

[0049] In the second embodiment, the ink flowing through the first flow path member 11 and the second flow path member 12 is non-conductive ink (for example, UV ink), and a conductive adhesive is provided at the lower end (other end) of the screw 63 (see FIGS. 4 and 5). The screw 63 is electrically connected to the first flow path member 11 by having its lower end attached to the first flow path member 11, and is also electrically connected to the second flow path member 12 via the conductive adhesive provided at its lower end.

[0050] According to this embodiment, the screw 63 and the second flow path member 12 are electrically connected to each other by the conductive adhesive interposed between the lower end of the screw 63 and the second flow path member 12. This makes it possible to achieve electrical grounding of the flow path member 10 (both the first flow path member 11 and the second flow path member 12) even when non-conductive ink (for example, UV ink) is used.

[0051] <Modification> Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design modifications are possible within the scope of the claims.

[0052] In the above-described embodiment (see FIG. 5), the extending portion 52 extends obliquely downward from the base portion 51, but it may extend obliquely upward from the base portion 51. Furthermore, the extending portion 52 is not limited to being linear, and may be bellows-shaped (i.e., having at least one portion extending obliquely upward and one portion extending obliquely downward). Furthermore, the extending portion 52 may be perpendicular to the side surface of the heat dissipation member 40.

[0053] The portion of the grounding member 50 that comes into point contact with the heat dissipation member 40 (see FIG. 6: the portion including the tip 52t of the extension portion 52) does not have to be rounded. For example, the tip 52t may be configured with an acute angle or may be configured with a horizontal surface.

[0054] The extending portion 52 does not necessarily have to have the through-hole 52x (see FIG. 6).

[0055] The extension 52 does not have to be flexible. The extension 52 is not limited to being made of stainless steel, but may be made of iron or any other material.

[0056] The ground member 50 is not limited to being in point contact with the heat dissipation member 40 (see FIG. 5), but may be in line contact with the heat dissipation member 40.

[0057] In the above-described embodiment (see FIGS. 5 and 6), the ground member 50 is connected to the flow path member 10 at two locations (the pair of connection portions 53) and to the heat dissipation member 40 at one location (the tip 52t of the extension portion 52), but is not limited to this. For example, the ground member 50 may be connected to each of the flow path member 10 and the heat dissipation member 40 at one location.

[0058] The material forming the flow path member 10 and the carriage 1c (holding member) may be a conductive material, and may be graphite, a conductive polymer material, or the like, in addition to metal.

[0059] The head 1 is not limited to a line type, but may be a serial type (a type in which liquid is ejected from nozzles onto a recording medium while moving in a scanning direction parallel to the paper width direction).

[0060] The recording medium is not limited to paper 9, but may be cloth, a substrate, or the like.

[0061] The actuator 20x is not limited to a piezoelectric type using a piezoelectric element, but may be of another type (for example, a thermal type using a heat generating element, an electrostatic type using electrostatic force, etc.).

[0062] The liquid ejected from the nozzles 15 is not limited to ink, but may be any liquid (for example, a treatment liquid that aggregates or precipitates components in the ink, etc.).

[0063] The printer 100 includes three heads 1 in the embodiment described above (see FIG. 1), but may include one, two, four or more heads 1.

[0064] The present invention is not limited to printers, but can also be applied to facsimiles, copiers, multifunction machines, etc. The present invention can also be applied to liquid ejection devices used for purposes other than image recording (for example, liquid ejection devices that eject conductive liquid onto a substrate to form a conductive pattern). [Explanation of symbols]

[0065] 1 head 1c Carriage (holding member) 10 Flow path member 15 nozzles 10x flow channels 20 Actuator member 20x Actuators 30 Driver IC (drive circuit) 40 Heat dissipation material 50 Grounding member 51 Base 51x Locating Holes 52 Extension 52t tip 52x through holes 53 Connection part (first connection part, second connection part) 63 Screws (connecting parts)

Claims

1. a flow path member made of a conductive material in which a flow path having a nozzle at a tip is formed; an actuator that applies energy to the liquid in the flow path to eject the liquid from the nozzle; a drive circuit electrically connected to the actuator and configured to drive the actuator; a heat dissipation member thermally connected to the drive circuit; a grounding member that is electrically grounded, The liquid ejection head is characterized in that the grounding member is electrically connected to both the flow path member and the heat dissipation member.

2. 2. The liquid ejection head according to claim 1, wherein the grounding member is in point contact with the heat dissipation member.

3. 3. The liquid ejection head according to claim 2, wherein the portion of said grounding member that comes into point contact with said heat dissipation member is rounded.

4. the grounding member includes a base portion and an extension portion extending from the base portion toward the heat dissipation member, the extension portion having the point contact portion at a tip end thereof; 4. The liquid ejection head according to claim 2, wherein the extending portion is flexible.

5. 5. The liquid ejection head according to claim 4, wherein a through hole is formed in the extending portion.

6. 6. The liquid ejection head according to claim 4, wherein the extending portion is made of stainless steel.

7. 7. The liquid ejection head according to claim 4, wherein the extending portion is inclined with respect to a surface including a portion of the heat dissipating member that comes into point contact with the tip of the extending portion.

8. the extension portion is provided at the center of the base portion in the longitudinal direction, the grounding member further includes a first connection portion provided at one end of the base in the longitudinal direction and a second connection portion provided at the other end of the base in the longitudinal direction, 8. The liquid ejection head according to claim 4, wherein the first connecting portion and the second connecting portion are each connected to the flow path member.

9. the first connection portion and the second connection portion are each connected to the flow path member via a connection member, the connecting member has one end connected to the first connecting portion or the second connecting portion and the other end connected to the flow path member, 9. The liquid ejection head according to claim 8, wherein the connecting member is electrically connected to the flow path member by a conductive adhesive interposed between the other end and the flow path member.

10. a holding member that holds the flow path member and the heat dissipation member and is made of a conductive material that is electrically insulated from the flow path member and the heat dissipation member, the holding member is electrically grounded; 10. The liquid ejection head according to claim 8, wherein the grounding member is fixed to the holding member at the center of the base portion, thereby being electrically connected to the holding member.

11. 11. The liquid ejection head according to claim 10, wherein two positioning holes are provided at positions sandwiching the center in the longitudinal direction of the base portion.

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