Liquid ejection head

Abstract

To provide a liquid discharge head in which liquid resistance at an electrically connected part between a flexible wiring board and a contact wiring board is improved.SOLUTION: In the liquid discharge head, an electrically connected part between a flexible wiring board and a contact wiring board is formed at a second surface side at the opposite side of a first surface in which a contact pad is arranged, in the contact wiring board.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection head. [Background technology]

[0002] In the inkjet field, which records by ejecting liquids such as ink, recording applications have become increasingly diverse in recent years, creating a demand for heads capable of ejecting a wide variety of inks. While aqueous pigment color inks are generally alkaline, ensuring greater freedom in ink composition, such as neutral or acidic inks or inks with a high solvent ratio, is expected to enable expansion into special media and special applications, as well as improve print quality.

[0003] A known liquid ejection head has a configuration in which a liquid ejection element substrate that ejects liquid is electrically connected to the liquid ejection device main body via a flexible wiring board and a contact wiring board. Patent Document 1 discloses a configuration in which the electrical connection between the flexible wiring board and the contact wiring board is protected by a sealant. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-313831 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the liquid ejection head of Patent Document 1, the sealant covering the electrical connection parts is exposed to the outside, so the corrosion resistance against the liquid used depends on the performance of the sealant of the electrical connection parts, the amount of sealant applied, etc. Therefore, when an acidic liquid that easily corrodes the electrical connection parts or a liquid containing a solvent that has high permeability to or solubility in the sealant is used, there is a risk that the reliability of the electrical connection parts will be reduced due to the adhesion of the mist or liquid that occurs during liquid ejection.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a liquid ejection head in which the liquid resistance at the electrical connection between the flexible wiring board and the contact wiring board is improved. [Means for solving the problem]

[0007] The liquid ejection head of the present invention comprises a liquid ejection element substrate having ejection elements that eject liquid, a flexible wiring board electrically connected to the liquid ejection element substrate, a contact wiring board having a first surface on which contact pads for electrical connection to the outside are provided and electrically connected to the flexible wiring board, and a support member having a support surface that supports a second surface opposite the first surface of the contact wiring board, and is characterized in that the electrical connection portion between the flexible wiring board and the contact wiring board is provided on the side of the second surface of the contact wiring board. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a liquid ejection head in which the liquid resistance at the electrical connection portion between the flexible wiring board and the contact wiring board is improved. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a perspective view of a liquid ejection head. [Figure 2] 1 is a cross-sectional view showing a liquid ejection head according to a first embodiment. [Figure 3] FIG. 10 is a cross-sectional view of a liquid ejection head of a comparative example. [Figure 4] 10A and 10B are diagrams showing a mounting path when a liquid ejection head is mounted on a liquid ejection device main body. [Figure 5] FIG. 10 is a cross-sectional view showing a liquid ejection head according to a second embodiment. [Figure 6] FIG. 10 is a cross-sectional view showing a liquid ejection head according to a third embodiment. [Figure 7] FIG. 2 is a perspective view of a liquid ejection head. [Figure 8] FIG. 10 is a cross-sectional view showing a liquid ejection head according to a fourth embodiment. [Figure 9] FIG. 1 is a diagram illustrating an external appearance of a liquid ejection device. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described.

[0011] The liquid ejection head and liquid ejection device of the present invention can be applied to devices such as printers, copiers, facsimiles with communication systems, word processors with printer units, and industrial recording devices combined with various processing devices. The liquid ejection head and liquid ejection device of the present invention can also be used for applications such as biochip production, electronic circuit printing, and printing on non-absorbent media.

[0012] Furthermore, since each embodiment described below is a suitable specific example of the present invention, various technically preferable limitations are attached. However, as long as it is in line with the idea of ​​the present invention, the present embodiment is not limited to the embodiments in this specification or other specific methods. Furthermore, it is also possible to combine the configurations of each embodiment as appropriate.

[0013] (First embodiment) FIG. 1 is a perspective view of a liquid ejection head 200 according to a first embodiment to which the present invention can be applied, showing a top view of a recording element substrate 201 (liquid ejection element substrate) of the liquid ejection head 200. The surface of the recording element substrate 201 is provided with ejection ports for ejecting ink as a liquid, and ink is ejected approximately perpendicular to the surface of the recording element substrate 201 using recording elements (liquid ejection elements) provided on the recording element substrate 201. FIG. 2 shows a cross section taken along line II-II in FIG. 1. FIG. 2 is a view rotated 180 degrees from FIG. 1, with the surface of the recording element substrate 201 facing downward in the figure, and the liquid ejection head 200 is shown in the same position as when printing inside the main body of the liquid ejection device.

[0014] The power required for discharging ink is supplied to the recording element substrate 201 from a contact wiring substrate 209, which is disposed on the side of the head housing 214 and makes electrical contact with the liquid discharge device main body, via a flexible wiring substrate 208. The flexible wiring substrate 208 is manufactured by etching copper foil attached to the upper side of a base film 205 to form a wiring layer 207, and covering it with a cover film 206. The head housing 214 is also referred to as a support member that supports the contact wiring substrate 209.

[0015] The liquid ejection head 200 is fixed at a predetermined position in the apparatus body, thereby completing electrical contact with the apparatus body. Specifically, electrical connection with the apparatus body is achieved by bringing contact pins 217 (FIG. 4) provided on the apparatus body into contact with contact pads 213 arranged on a contact wiring board 209.

[0016] The flexible wiring substrate 208 has a flat shape around the periphery of the front surface of the recording element substrate 201 and also functions as a cap surface that abuts against a main body cap (not shown). By abutting the main body cap against this cap surface and applying reduced pressure or suction, it is possible to discharge viscous ink near the ejection ports and to prevent liquid from evaporating from the ejection ports when not in use. The cap surface is at a height approximately equal to or higher than the ejection port surface on which the ejection ports of the recording element substrate 201 are formed, and also functions to prevent stress from being applied to the ejection port surface and the recording element substrate 201 due to paper jams or the like during printing. In this embodiment, an adjustment plate 204 is disposed between the support member 202 and the flexible wiring substrate 208 to adjust the height of the cap surface relative to the support member 202 that supports the recording element substrate 201.

[0017] For this reason, the cap surface of the flexible wiring substrate 208, i.e., the surface of the flexible wiring substrate 208 located on the front side of the recording element substrate 201, is required to be made of a material that is strong and has excellent ink resistance. Typically, for manufacturing reasons, the base film 205 of the flexible wiring substrate 208 is thicker and stronger than the cover film 206. Therefore, it is preferable to position the base film 205 on the outside of the liquid ejection head 200 so that the cap surface is formed on the base film 205 side of the flexible wiring substrate 208, which uses a polyimide film that is strong and has excellent ink resistance. For example, in this embodiment, the thickness of the base film 205 is 50 μm, and the thickness of the cover film 206 is 4.4 μm.

[0018] The electrode pads 203 of the recording element substrate 201 are arranged on the same side as the ejection port surface on which the ejection ports for ejecting liquid are formed, and therefore, electrical connection and sealing protection with the flexible wiring substrate 208 constituting the cap surface arranged on the same side can be easily achieved. Specifically, the electrical connection between the recording element substrate 201 and the flexible wiring substrate 208 is achieved by using a bonder to connect the flying leads 207a of the flexible wiring substrate 208 to the electrode pads 203. This electrical connection is covered and protected by a sealant 215 that has high ink resistance.

[0019] In this embodiment, a thermosetting epoxy-based sealing material is used as the sealing material 215. In the heat-curing process of the sealing material, the recording element substrate 201, the support member 202 that supports it, the flexible wiring substrate 208, and the adjusting plate 204 that supports it are also heated. Therefore, when the heat-curing process of the sealing material 215 is performed, engineering resin or alumina material that has heat resistance (for example, 150°C or higher) is selected for the support member 202 and the adjusting plate 204.

[0020] Next, the configurations of the flexible wiring board 208 and the contact wiring board 209, and the electrical connection between these components will be described with reference to FIG.

[0021] The contact wiring board 209 is a two-layer board, and wiring layers 211 are provided on both sides of a glass epoxy board 210 serving as a base material. Part of the wiring layer 211 is exposed on the surface of the epoxy board 210 opposite to the surface facing the housing 214 (i.e., the outer surface of the liquid ejection head 200), forming contact pads 213. Electrode pads 211a for connecting to the flexible wiring board 208 are arranged on a surface 209b (second surface) opposite to the surface 209a (first surface) on which the contact pads 213 are provided of the contact wiring board 209. Areas other than the contact pads 213 and the electrode pads 211a are protected from ink mist and the like by a resist material 212.

[0022] In the flexible wiring board 208, a wiring layer 207 is etched on a base film 205, and is covered with a cover film 206. For connection with a contact wiring board 209, the wiring layer 207 is exposed at the end of the base film 205, and forms an electrode pad 207b.

[0023] An end of surface 209b of contact wiring substrate 209 is joined to an end of base film 205 of flexible wiring substrate 208. Electrode pads 207b of flexible wiring substrate 208 and electrode pads 211a of contact wiring substrate 209 are provided on the same surface, i.e., on surface 209b opposite surface 209a of contact wiring substrate 209 on which contact pads 213 are provided. They are electrically connected by bonding with conductive wires 218 (gold wires). Electrical connection portions 220 between contact wiring substrate 209 and flexible wiring substrate 208 are covered and protected by sealing material 216.

[0024] As described above, in this embodiment, the electrical connection portion 220 between the flexible wiring substrate 208 and the contact wiring substrate 209 is disposed on the surface 209b of the contact wiring substrate 209 opposite the side on which the contact pads 213 are provided. As described above, the electrical connection portion 220 between the contact wiring substrate 209 and the flexible wiring substrate 208 is not exposed to the outside of the liquid ejection head 200, which makes it possible to provide a configuration that is more reliable against ink mist and the like. Furthermore, since the electrode pads 211a of the contact wiring substrate 209 and the electrode pads 207b of the flexible wiring substrate 208 face the housing 214 of the head 200, it is possible to ensure higher reliability against external impacts and the like.

[0025] Furthermore, the amount of protrusion of the sealing material 216 covering the electrical connection portion 220 toward the contact pad 213 can be reduced. The sealing material 216 may protect the outer surface of the flexible wiring substrate 208 (the surface opposite the surface facing the housing 214) near the end portion on the contact wiring substrate 209 side. In this case, too, it is possible to reduce the risk of the sealing material 216 running onto the surface of the contact pad 213. Specifically, as shown in FIG. 2, it is preferable that the sealing material 216 has a shape that does not protrude in the direction of the arrow from the imaginary line "a" representing the outermost surface of the contact pad 213. Even if the application path results in a shape that protrudes from the imaginary line a in the direction of the arrow, the amount of protrusion is reduced by the thickness of the flexible wiring substrate 208, making it possible to reduce the amount of protrusion.

[0026] Next, a liquid ejection head 100 of a comparative example will be described with reference to Fig. 3. Fig. 3 shows a cross-sectional view of the liquid ejection head 100 of the comparative example, including a recording element substrate 101 and a contact wiring substrate 109 that makes electrical connection with the liquid ejection device main body.

[0027] In the liquid ejection head 100 of the comparative example, a contact wiring board 109 and a flexible wiring board 108 are connected to supply power from the liquid ejection device main body to the recording element board 101. The flexible wiring board 108 uses a TAB tape or the like that is configured with a wiring layer 107 made of copper or the like on a base film 105 and a cover film 106 that covers the wiring layer 107.

[0028] For reliability reasons, the thick base film 105 of the substrate is exposed to the outside, forming a cap surface (not shown) for capping the periphery of the recording element substrate 101. The electrode pads 103 of the recording element substrate 101 are connected to flying leads arranged on the wiring layer 107 of the flexible wiring substrate using a bonder. The contact wiring substrate 109 and the electrode pads arranged on the wiring layer 107 of the flexible wiring substrate 108 are crimped and connected using an anisotropic conductive film (ACF) (not shown). These electrical connections are bonded using heat, vibration, and pressure. Even if gold-plated, liquids such as ink easily penetrate the copper wiring, potentially damaging electrical reliability. Therefore, these electrical connections are covered with sealants 115 and 116 to prevent liquid penetration and ensure electrical reliability. Since the sealant 115 comes into contact with ink, a highly ink-resistant epoxy resin sealant that hardens at temperatures exceeding 100°C is often used. On the other hand, since the sealant 116 is placed near the connection part with the main body, it is sufficient to prevent adhesion of floating mist and the like inside the printer main body, and a room temperature curing silicone sealant that has lower ink resistance than the sealant 115 may be used. This has the advantage that the sealing protection can be completed regardless of when it is applied, before or after fixing the contact wiring board 109 to the housing 114 of the liquid ejection head 100, and therefore the process sequence can be freely set without having to consider deterioration of accuracy due to thermal deformation, etc.

[0029] When electrode pads that can be pressure-bonded from the back side are formed on flexible wiring board 108 using wiring layer 107, the electrode pads are exposed on the side of cover film 106. Therefore, during ACF pressure bonding, the flexible wiring board is mounted on the same surface as contact pads 113 of contact wiring board 109. That is, in the comparative example, electrical connection portions 120 between flexible wiring board 108 and contact wiring board 109 are arranged on the same side as contact pads 113 of contact wiring board 109. Furthermore, sealing material 116 that covers this electrical connection portion 120 is arranged so as to protrude outward from the outermost surface of contact pads 113.

[0030] In contrast to this comparative example, in the present embodiment as described above, the amount of protrusion of the sealant 216 is reduced. The effect of reducing the amount of protrusion of the sealant 216 will be described with reference to FIG. 4. FIG. 4 shows the mounting path when the liquid ejection head 200 is mounted to the liquid ejection device main body. FIG. 4(a) is a cross-sectional view showing the mounting path of the liquid ejection head 200 of this embodiment, and FIG. 4(b) is a cross-sectional view showing the mounting path of the liquid ejection head 100 of the comparative example shown in FIG. 3. The liquid ejection head 200 of this embodiment is intended to be replaced by the user. As shown in FIG. 4, the liquid ejection head 200 is rotated to mount the liquid ejection head 200 on the device main body, and contact pins 217 provided on the liquid ejection device main body are brought into contact with contact pads 213.

[0031] 4(b), if the sealing material 116 protrudes toward the surface of the contact wiring board on which the contact pads 113 are provided, there is a risk that the sealing material 116 will come into contact with the contact pins 117 when the head is attached. If the sealing material 116 is scraped off by such unexpected contact, electrical reliability may be impaired. Even if a high-strength sealing material such as thermosetting epoxy is used as the sealing material 116, contact between the contact pins 117 and the sealing material 116 is undesirable because scraping of the contact pins 117 or the adhesion of dust can reduce the reliability of the electrical connection.

[0032] In contrast to this, in this embodiment, the amount of protrusion of the sealing material 216 toward the surface 209a of the contact wiring substrate 209 on which the contact pads 213 are provided can be reduced, thereby reducing contact between the sealing material 216 and the contact pins 217. This ensures the electrical reliability of the electrical connection portion 220.

[0033] As explained in the comparative example, in order to ensure ease of assembly and process setup and reduce manufacturing costs, it is preferable to use a one-component, room-temperature-curing silicone-based sealant as the sealant 216. However, one-component, room-temperature-curing sealants often have a higher ink permeability than one-component, heat-curing sealants, and tend to result in lower reliability of the electrical mounting section. Furthermore, room-temperature-curing sealants often have lower strength than heat-curing sealants. Even when such a sealant 216 is used, the electrical reliability of the electrical connection section 220 can be ensured in this embodiment.

[0034] Furthermore, the smaller the device body becomes and the smaller the space available for mounting the liquid ejection head becomes, the greater the possibility of contact between the sealing material and the contact pins, so the configuration of this embodiment is also effective in terms of miniaturizing the device body.

[0035] Furthermore, it is preferable to provide a recess 219 on the support surface of the head housing 214 that supports the contact wiring substrate 209, and to configure the recess 219 so that the electrical connection portion 220 and the sealing material 216 that covers it can be accommodated therein. This makes it possible to prevent the liquid ejection head 200 from becoming larger. It is also preferable that the inner surface of the recess 219 and the sealing material 216 are spaced apart so as not to come into contact with each other. This reduces the risk of the sealing material 216 interfering with the head housing 214 and improves the reliability of the electrical connection portion 220. Furthermore, in this embodiment, when the contact wiring substrate 209 is viewed from above, the recess 219 is positioned offset from the contact pads 213. This allows the pressure from the contact pins 217 on the contact pads 213 to be received by the support surface of the contact wiring substrate 209 of the head housing 214.

[0036] Furthermore, the configuration of this embodiment, in which the electrical connection section 220 is not disposed on the outside of the liquid ejection head 200, is highly reliable against irregular damage caused by contact with the user or dropping the head, even when the head is not being attached.

[0037] The sealant 216 is not limited to a room temperature curing silicone sealant. For example, it is also possible to use a urethane sealant or a two-component room temperature curing sealant that has sufficient sealing performance when cured at room temperature. Furthermore, in the case of a system that ejects ink that is resistant to sealants such as strong acids, strong alkalis, and high-concentration solvents, a heat-curing epoxy sealant may be used as the sealant 216. (Second embodiment) 5 is a cross-sectional view of a liquid ejection head 300 according to the second embodiment. The appearance of the liquid ejection head 300 according to this embodiment is almost the same as that of the above-described embodiment, and FIG. 5 is a cross-sectional view of this embodiment corresponding to FIG.

[0038] Power is supplied to the recording element substrate 301 from a contact wiring substrate 309 via a flexible wiring substrate 308. The flexible wiring substrate 308 includes a base film 305, a wiring layer 307, and a cover film 306. In this embodiment, a polyimide film is used for the base film 305, and a polyimide film is also used for the cover film 306.

[0039] The recording element substrate 301 and the flexible wiring substrate 308 are electrically connected by connecting the electrode pads 303 formed on the recording element substrate 301 to the flying leads 307a formed at the ends of the wiring layer 307 using a bonder.

[0040] On a surface 309b of the contact wiring substrate 309 opposite to the surface 309a on which the contact pads 313 are arranged, electrode pads 311a are provided, whereby the wiring layer 311 is exposed from the resist material 312. Furthermore, on the flexible wiring substrate 308, electrode pads 307b are provided, whereby the wiring layer 307 formed on the base film 305 is exposed from the cover film 306. The electrode pads 311a and 307b are pressure-bonded together via an anisotropic conductive film (ACF) (not shown) to form an electrical connection 320, electrically connecting the contact wiring substrate 309 and the flexible wiring substrate 308. That is, an end of the surface 309b of the contact wiring substrate 309 and an end of the flexible wiring substrate 308 are joined. In this embodiment, as in the above-described embodiment, the electrical connection 320 is covered and protected by a sealant 316. It is preferable to use a room-temperature curing silicone sealant as the sealant 316. Furthermore, similar to the above-described embodiment, the head housing 314 is provided with a recess 319, and the electrical connection part 320 and the sealing material 316 that covers it are housed inside this recess 319, so as to avoid interference between the head housing 314 and the sealing material 316. This makes it possible to prevent the liquid ejection head 300 from becoming too large.

[0041] Flying lead bonding and ACF compression bonding for electrical connection have shorter manufacturing cycle times than wire bonding using gold wires or the like, and are expected to reduce production costs. However, in order to connect the contact wiring board 309 and the flexible wiring board 308 by ACF compression bonding, as in this embodiment, the electrode pads 311a and 307b are arranged to face each other. In order to arrange the electrical connection portion 320 on the side opposite the surface 309a on which the contact pads 313 are provided, the electrode pads 307b exposed from the cover film 306 of the flexible wiring board 308 are arranged to face the outside of the head 300. That is, in the liquid ejection head 300, the contact wiring board 309 is arranged so that the cover film 306 is located on the outside. As a result, the externally exposed surface of the flexible wiring board 308 and the cap surface surrounding the recording element substrate 301 are formed by the cover film 306. When cover film 306 is disposed on the outside in this manner, in order to ensure the strength of cover film 306, it is preferable that cover film 306 has a thickness equal to that of base film 305 or a thickness required for durability. In this embodiment, cover film 306 is formed by stacking two films, each having a thickness of 4.4 μm, for example.

[0042] However, stacking multiple general-purpose cover films or custom-ordering a thicker cover film to increase the thickness can increase the component cost of the flexible wiring board. While it is possible to use a polyimide film, like the base film 305, for the cover film 306, this tends to be more expensive than an aramid film. Therefore, this embodiment is preferably applied when inks other than those mentioned above are used, rather than when more reliable inks, such as those containing strong acids, strong alkalis, or high-concentration solvents, are used. When inks other than those mentioned above are used, the total cost can be reduced by appropriately setting the thickness of the cover film 306 of this embodiment.

[0043] Furthermore, similarly to the above-described embodiment, this embodiment can prevent the sealing material 316 from protruding from the outer surface 309a of the contact wiring substrate 309, or can suppress the possibility of the sealing material 316 protruding from the outer surface 309a of the contact wiring substrate 309.

[0044] One difference from the above-described embodiment is that, compared to the above-described embodiment, if there is unexpected contact that scrapes off the sealant 316, there is a possibility that the electrode pads 307a of the electrical connection portions 320 may be exposed. However, in this embodiment, even if the thickness of the sealant 316 is increased by the thickness of the contact wiring substrate 309, it is possible to maintain a head outer shape that is approximately the same as the configuration of the liquid ejection head 300 shown in the comparative example in FIG. 3. In other words, this embodiment can prevent the head 300 from becoming larger while suppressing the risk of the electrical connection portions 320 being exposed by increasing the thickness of the sealant 316. Such an increase in the thickness of the sealant 316 delays ink penetration into the electrical connection portions 320, and is therefore also effective in improving ink resistance.

[0045] As a modification of this embodiment, in a configuration in which electrical connection is made by pressure bonding or a bonder from the side of base film 305, the ACF and flying leads 307b may be replaced with conductive bumps (gold bumps) to form a so-called COF (Chip On Film) connection. Even with such a connection configuration, the same effects as those described above can be obtained.

[0046] (Third embodiment) 6 is a cross-sectional view of a liquid ejection head 400 according to a third embodiment. The appearance of the liquid ejection head 400 according to this embodiment is substantially the same as that of the above-described embodiment, and FIG. 6 is a cross-sectional view of this embodiment corresponding to FIG. 2. In this embodiment, as in the second embodiment, a contact wiring board 409 and a flexible wiring board 408 are electrically connected by pressure-bonding via an ACF on a surface 409b opposite to a surface 409a of the contact wiring board 409 on which contact pads 413 are provided. An electrical connection portion 420 at which electrode pads 411a of the contact wiring board 409 and electrode pads 407b of the flexible wiring board 408 are connected is covered and protected by a sealant 416 and is housed in a recess 419 provided in a housing 414.

[0047] The electrical connection between the recording element substrate 401 and the flexible wiring substrate 408 is different from that in the above-described embodiment. Specifically, the electrode pads 403 of the recording element substrate 401 are bonded to electrode pads 407a formed by a wiring layer 407 etched on the base film 405 of the flexible wiring substrate 408 using gold wires 418. Wire bonding involves discharging electricity at the tip of the gold wire to melt the metal and form a ball, and then using heat, ultrasound, pressure, or the like to complete the connection. Therefore, wire bonding is performed while the recording element substrate 401 and the flexible wiring substrate 408 are fixed in place. Therefore, in this embodiment, wire bonding is performed while the recording element substrate 401 and the flexible wiring substrate 408 are fixed to the support member 402. In the above-described embodiment, the flexible wiring substrate constituted a cap surface around the recording element substrate. However, in this embodiment, a face cover 404 (plate) for forming a cap surface is arranged on the surface of the flexible wiring substrate 408 facing the recording element substrate 401. In the configuration of this embodiment, a cover film 406 is disposed on the externally exposed side of flexible wiring board 408, but since the cap surface is formed by face cover 404, there is no need to make the cover film 406 thicker than necessary. The number of components is almost the same as in the configurations of the other embodiments, so the configuration can be achieved without incurring additional component costs.

[0048] (Fourth embodiment) Fig. 7 is a perspective view showing a liquid ejection head 500 according to a fourth embodiment to which the present invention can be applied, showing a recording element substrate 501 from above. Fig. 8 is a cross-sectional view taken along line VIII-VIII shown in Fig. 7. In this embodiment, a contact wiring substrate 509 has at least three wiring layers 511. Furthermore, a flexible wiring substrate 508 has a plurality of wiring layers 507.

[0049] In the liquid ejection head 500, a contact wiring board 509 having contact pads 513 for connecting to the printer body is disposed on the side of a head housing 514 so that power can be supplied from the printer body to the recording element substrate 501. Power is supplied to the recording element substrate 501 from the contact wiring board 509 via a flexible wiring board 508. Because the recording element substrate 501 has a large number of nozzles, if electrode pads were disposed only on the short sides of the recording element substrate 501, the width of the recording element substrate 501 would need to be increased, resulting in a reduced number of nozzles. For this reason, in this embodiment, the electrode pads 503 are disposed on the edges of the long sides of the recording element substrate 501. As in the third embodiment, the recording element substrate 501 and the flexible wiring board 508 are electrically connected by wire bonding 518, and the electrical connection is covered and protected by a sealant 515.

[0050] The flexible wiring board 508 uses an FPC (Flexible Printed Circuit) that has multiple wiring layers 507 made of copper or the like on a base film 505 and multiple cover films 506 that cover the wiring layers 507. In this embodiment, LVDS (Low Voltage Differential Signaling) high-speed differential signals are used for drive control of the recording element substrate 501, rather than single-ended signals. This configuration reduces the number of wiring lines for drive control and the cost by miniaturizing the flexible wiring board 508. In this embodiment, to improve the noise resistance characteristics of the LVDS signal lines, a microstrip is formed by the two wiring layers 507 of the flexible wiring board 508. A microstrip is a structure in which a ground plane is provided on one side and signal lines are arranged on the opposing side, sandwiching an insulating layer such as the base film 505. The flexible wiring board 508 has electrode pads 507b formed by exposing the wiring layer 507 from the cover film 506. In this embodiment, for example, the base film 505 is a 25 μm thick polyimide film, and the cover film 506 is a two-ply structure of 4 μm thick aramid film. As a variation, a 50 μm thick LCP (liquid crystal polymer) with high high frequency characteristics and low dielectric constant may be used as the base film. Similarly, a 12.5 μm thick polyimide film may be used to impart high durability to the cover film.

[0051] Similarly, the LVDS signal wiring on the contact wiring board 509 has a microstrip or strip configuration (the LVDS signal line is sandwiched between ground planes on both sides via an insulating layer 510), resulting in a board configuration with four wiring layers 511. Parts of the wiring layers 511 are exposed to form contact pads 513. Electrode pads 511a for connection to the flexible wiring board 508 are arranged on a surface 509b opposite to the surface 509a on which the contact pads 513 of the contact wiring board 509 are provided. Areas other than the contact pads 513 and the electrode pads 511a are protected from ink mist and the like by a resist material 512.

[0052] The electrode pads 511a and 507b are pressure-bonded together via an anisotropic conductive film (ACF) (not shown) to form an electrical connection 520, electrically connecting the contact wiring board 509 and the flexible wiring board 508. The electrical connection 520 is provided on a surface 509b of the contact wiring board 509 opposite to a surface 509a on which the contact pads 513 are provided. The electrical connection 520 is covered with a sealant 516 and is housed in a recess 519 provided in the housing 514. The sealant 516 is also arranged on the outside of the liquid ejection head 500, but the amount of protrusion can be reduced as in the above-described embodiment.

[0053] In this embodiment, the cover film 506 of the flexible wiring substrate 508 is exposed on the surface on the recording element substrate 501 side. Therefore, as in the third embodiment, a face cover 504 for forming a cap surface is disposed on the surface of the flexible wiring substrate 508 on the recording element substrate 501 side.

[0054] In this embodiment, since the wiring layer 511 of the contact wiring substrate 509 has a four-layer configuration, less substrate area is required to connect each wire to each contact pad 513 compared to a two-layer configuration. Therefore, the contact wiring substrate 509 allows the contact pads 513 to be closer to the flexible wiring substrate 508, and the size of the contact wiring substrate 509 can be reduced, leading to cost reduction.

[0055] In the liquid ejection head of the comparative example shown in FIG. 3, if the contact pads are positioned closer to the flexible substrate, the possibility of the main body contact pins coming into contact with the sealant 116 increases. In this embodiment, the sealant 516 does not protrude beyond the surface 513a of the contact wiring substrate 509 on which the contact pads are provided, and therefore the risk of contact with the main body contact pins is low. This makes it possible to position the contact pads 513 on the contact wiring substrate 509 closer to the flexible wiring substrate 508, thereby enabling the miniaturization of the contact wiring substrate 509. In this embodiment, as shown in FIG. 8, the contact pads 513 are positioned closer to the bottom of the figure, and the contact pads 513 and the electrical connection portions 520 can be arranged so that at least a portion of each overlap with each other when the contact wiring substrate 509 is viewed in plan.

[0056] Furthermore, the flexible wiring substrate 508 has a bent portion that bends from the recording element substrate 501 side toward the contact wiring substrate 509 side, and a bending reaction force is generated that causes the bent portion of the flexible wiring substrate 508 to return to its original flat shape. In the case of the liquid ejection head of the comparative example shown in FIG. 3 , the bending reaction force is generated in a direction that peels off a pressure-bonded bond such as an OLB (Outer Lead Bonding) bond that electrically connects the flexible wiring substrate 108 and the contact wiring substrate 109. If the bending reaction force becomes large, there is a concern that the electrical connection after OLB bonding may be peeled off. In this embodiment, the bending reaction force acts in the electrical connection portion 520 in a direction different from the peeling direction of the pressure-bonded OLB bond, and therefore the configuration can be said to be resistant to OLB bond peeling due to the bending reaction force.

[0057] (Liquid discharge device) 9 is a diagram showing the appearance of an example of a liquid ejection device (inkjet printer) equipped with the above-mentioned liquid ejection head. This is a so-called serial scan type printer 70, which forms an image by scanning the liquid ejection head in a direction perpendicular to the transport direction of the recording medium.

[0058] The configuration of this printer 70 and its operation during liquid ejection will be outlined below. First, a recording medium (not shown) fed from an auto sheet feeder (ASF) 82 is transported toward a printing position by a paper feed roller (neither of which is shown) driven by a paper feed motor via gears. At a predetermined transport position, a timing belt 74 driven by a carrier motor 1710 causes a carriage 71 to scan along a guide shaft 88 extending in a direction perpendicular to the transport direction. During this scanning process, ejection is performed from the ejection openings of a liquid ejection head detachably mounted on the carriage 71, and a certain bandwidth corresponding to the array of the ejection openings is recorded. The recording medium is then transported, and the next bandwidth is recorded.

[0059] A flexible cable 72 is attached to the carriage 71 to supply signals for driving the liquid ejection head mounted thereon. One end of the cable is connected to a substrate 73 having contact pins 217 (FIG. 4) provided on the portion of the carriage 71 where the liquid ejection head is mounted. The other end of the flexible cable 72 is connected to a control circuit (not shown) that controls the printer. In addition, a recovery unit 89 for performing recovery processing for the liquid ejection head is provided in part of the movable range of the carriage 71, for example, in the home position of the liquid ejection head. [Explanation of symbols]

[0060] 101, 201, 301, 401, 501: Recording element substrate (liquid ejection element substrate) 108, 208, 308, 408, 508 Flexible wiring board 109, 209, 309, 409, 509 Contact wiring board 113, 213, 313, 413, 513 contact pads 114, 214, 314, 414, 514 head housing 116, 216, 316, 416, 516 Encapsulant 120, 220, 320, 420, 520 Electrical Connections

Claims

1. a liquid ejection element substrate provided with ejection elements that eject liquid; a flexible wiring substrate electrically connected to the liquid ejection element substrate; a contact wiring board having a first surface provided with contact pads for electrical connection to the outside, the contact wiring board being electrically connected to the flexible wiring board; a support member having a support surface that supports a second surface of the contact wiring substrate opposite to the first surface; In a liquid ejection head having an electrical connection portion between the flexible wiring board and the contact wiring board is provided on the second surface side of the contact wiring board, The liquid ejection head, wherein the support member has a recess on the support surface for accommodating the electrical connection portion covered with a sealing material.

2. 2. The liquid ejection head according to claim 1, wherein the contact pads and the recesses are arranged at positions that are offset from each other when the contact wiring substrate is viewed from above.

3. The liquid ejection head according to claim 1 , wherein the contact pads and the electrical connection portions at least partially overlap each other when the contact wiring substrate is viewed from above.

4. 4. The liquid ejection head according to claim 1, wherein the sealing material is a room temperature curing material.

5. the flexible wiring board has the electrical connection portion with the contact wiring board at an end thereof, the second surface side of the contact wiring board and the end portion of the flexible wiring board are joined together, A liquid ejection head as described in any one of claims 1 to 4, wherein a sealing material is arranged near the end of the flexible wiring board on the side of the first surface of the flexible wiring board, and the sealing material does not protrude toward the first surface compared to the first surface of the contact wiring board.

6. A liquid ejection element substrate having ejection elements that eject liquid; a flexible wiring substrate electrically connected to the liquid ejection element substrate; a contact wiring board having a first surface provided with contact pads for electrical connection to the outside, the contact wiring board being electrically connected to the flexible wiring board; a support member having a support surface that supports a second surface of the contact wiring substrate opposite to the first surface; In a liquid ejection head having an electrical connection portion between the flexible wiring board and the contact wiring board is provided on the second surface side of the contact wiring board, the flexible wiring board has the electrical connection portion with the contact wiring board at an end thereof, the second surface side of the contact wiring board and the end portion of the flexible wiring board are joined together, A liquid ejection head, wherein a sealing material is arranged on the first surface side of the flexible wiring board near the end of the flexible wiring board, and the sealing material does not protrude toward the first surface side compared to the first surface of the contact wiring board.

7. the flexible wiring substrate has a bent portion that is bent between a second electrical connection portion with the liquid ejection element substrate and the electrical connection portion with the contact wiring substrate, 7. A liquid ejection head as described in any one of claims 1 to 6, wherein an electrode pad provided on the surface of the flexible wiring board facing outward from the bent portion and an electrode pad provided on the second surface of the contact wiring board are joined together, thereby electrically connecting the flexible wiring board and the contact wiring board.

8. 8. The liquid ejection head according to claim 1, wherein the flexible wiring board and the contact wiring board are connected via an anisotropic conductive film or conductive bumps.

9. 7. The liquid ejection head according to claim 1, wherein the flexible wiring board and the contact wiring board are connected via a conductive wire.

10. 10. The liquid ejection head according to claim 1, wherein the liquid ejection element substrate and the flexible wiring substrate are connected via a conductive wire.

11. 10. The liquid ejection head according to claim 1, wherein the liquid ejection element substrate and the flexible wiring board are connected via flying leads provided on the flexible wiring board.

12. The liquid ejection head according to claim 1 , wherein the flexible wiring board comprises a plurality of wiring layers.

13. 13. The liquid ejection head according to claim 1, wherein the contact wiring substrate comprises at least three wiring layers.

14. the flexible wiring board includes a base film, a wiring layer disposed on an upper side of the base film, and a cover film that covers the wiring layer and has a thickness smaller than that of the base film; In a region where the flexible wiring board is supported by the support member, the cover film is located closer to the ejection port surface of the liquid ejection element substrate from which liquid is ejected than the base film, The liquid ejection head according to claim 1 , further comprising a plate that covers the cover film.

15. A liquid ejection head described in any one of claims 1 to 14, which is mounted on a serial scan type liquid ejection device and is configured to scan in a direction intersecting the transport direction of the recording medium.

16. A liquid ejection head described in any one of claims 1 to 15, having an adjustment plate between the surface of the support member that supports the liquid ejection element substrate and the flexible wiring substrate.

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