JP2009149057A - Inkjet recording head and inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording head which is high in recording reliability with the temperature unevenness suppressed even when recording is carried out using an elongated and high-density recording head. <P>SOLUTION: A temperature equalizing member such as a heat pipe or a cooling path is prepared between a first support substrate and a second support substrate or in the first support substrate. Hence the temperature can be equalized among a plurality of the second support substrates, and eventually the temperature among recording element substrates joined to respective support substrates can be equalized. Moreover, the temperature equalizing member can be set near the recording element substrate, enabling more efficient equalization of the temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a recording head for ejecting ink and an ink jet recording apparatus, and more particularly to a structure for cooling or temperature adjustment of the recording head.

  Conventional ink jet recording apparatuses using recording heads that eject ink have low running costs and can be miniaturized, so they are widely used for information output in computer equipment and are commercialized. Yes.

  In recent years, in order to realize high-speed and high-definition image recording, it is desired to realize a recording head having a longer recording width (arrangement length of discharge ports). Specifically, a recording head having a length of 4 inches to 13 inches or the like is also required.

  When the recording head is lengthened and densified in this manner, the energy input to the recording head increases, and the temperature rise of the recording head during recording becomes significant. As a result, for example, there may be a problem that the discharge amount fluctuation for each page becomes large or the recording characteristics at the time of continuous recording deteriorate.

  Conventionally, as a configuration for dealing with such a temperature change of the recording head, a recording pipe described in Patent Document 1, Patent Document 2, and Patent Document 3 is provided with a heat pipe or a heat radiating member, and the recording head is cooled, or Some have been proposed to make the temperature uniform.

JP-A-8-276575 Japanese Patent No. 2656834 Japanese Patent No. 2744475

  However, the configuration for cooling the recording head or making the head temperature uniform described in Patent Document 1 or the like may be insufficient in terms of efficiency. That is, in the conventional configuration, a heat pipe or a heat radiating member is attached or externally attached to the completed recording head, so that the distance between the recording element substrate, which is the heat source of the recording head, and the heat pipe cannot be made very close. There's a problem. In addition, since a heat pipe or the like is retrofitted, there is a problem that the contact area between the heat pipe and the recording head is limited.

  As described above, the conventional cooling or temperature equalization configuration has low efficiency in cooling the recording head or equalizing the head temperature, and its function may not be sufficient. Even with the conventional configuration, the effect of cooling and temperature equalization may be sufficient depending on the recording conditions. However, in particular, when trying to improve the continuous recording performance with a recording head that is longer and higher in density, recording defects (density unevenness, non-ejection due to air bubbles) due to temperature unevenness or temperature rise of the recording head. There is a risk that it cannot be suppressed.

  An object of the present invention is to provide a recording head and an ink jet recording apparatus which have high recording reliability in which temperature unevenness is suppressed even when recording is performed using, for example, a long and high-density recording head.

  Therefore, in the present invention, an inkjet recording head is supported by a plurality of recording element substrates each including a thermal energy generating element for ejecting ink, a first support substrate, and the first support substrate. And a plurality of second support substrates that respectively support the recording element substrate, and between the first support substrate and the second support substrate or in the first support substrate. And a temperature uniformizing member.

  According to the above configuration, a plurality of second supports are provided by providing a temperature equalizing member such as a heat pipe between the first support substrate and the second support substrate or inside the first support substrate. Temperature unevenness can be reduced between the substrates. As a result, it is possible to reduce temperature unevenness between the recording element substrates disposed on the second support substrate. Then, the temperature equalizing member is disposed so as to be sandwiched between the first support substrate and the second support substrate, or disposed inside the first support substrate, so that the temperature equalizing member generates heat as much as possible. It is possible to approach the recording element substrate as a source. As a result, the temperature unevenness can be efficiently reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 to 6 are explanatory views for explaining an ink jet recording head and an ink jet recording apparatus in which the present invention is implemented.

  The recording head H1000 shown in FIG. 1 includes an electrothermal conversion element as a thermal energy generation element. The electrothermal conversion element causes thermal energy to act on ink according to an electrical signal to generate bubbles due to film boiling. Ink is ejected from the outlet. As shown in the exploded perspective view of FIG. 2, the recording head H1000 includes a recording element unit H1001 and an ink supply member H1500 of an ink supply unit H1002. As shown in the exploded perspective view of FIG. 3, the recording element unit H1001 includes a recording element substrate H1100, a support substrate H1200, an electric wiring substrate H1300, a plate H1400, and a filter member H1600. A plurality of recording element substrates H1100 (four in the example shown in the figure) are provided, and a plurality of ejection openings are arranged on each recording element substrate as described below. Then, two sets of the four recording element substrates H1100 are arranged so as to partially overlap each other (in a zigzag pattern), thereby forming an array of ejection openings having a predetermined length as the entire recording head. is doing.

  FIG. 4A is a diagram for explaining the detailed configuration of the recording element substrate H1100, and FIG. 4B is a cross-sectional view taken along the line IVB-IVB shown in FIG. The recording element substrate H1100 includes a thin Si substrate H1108 having a thickness of 0.5 to 1 mm, for example. The substrate H1108 is formed with an ink supply port H1101 which is a long groove-like through-hole as an ink supply path. The ink supply port H1101 is formed by anisotropic etching using the crystal orientation of the Si substrate H1108. In addition, a plurality of electrothermal conversion elements H1102 are arranged in a staggered manner on both sides of the opening of the ink supply port H1101 on the upper surface of the Si substrate H1108, and for supplying power to these electrothermal conversion elements H1102 Electric wiring such as Al is formed by a film forming technique. On the upper surface of the Si substrate H1108, an electrode H1103 connected to the electric wiring and for supplying electric power from the outside is provided.

  On the Si substrate H1108, a flow path forming member H1110 is provided so as to overlap. An ink flow path H1104, a discharge port H1105, and a foaming chamber H1107 corresponding to each of the plurality of electrothermal conversion elements H1102 are formed on this member. ing. Here, the discharge port H1105 is formed to face the corresponding electrothermal conversion element H1102. As a result, the thermal energy generated by the electrothermal conversion element H1102 generates bubbles in the ink supplied via the ink supply port H1101, and the ink can be discharged from the corresponding discharge port.

Referring to FIG. 3, the support substrate H1200 is formed of an alumina (Al ₂ O ₃ ) material having a thickness of 0.5 mm to 10 mm, for example. The material of the support substrate is not limited to alumina. For example, the support substrate has a linear expansion coefficient equivalent to that of the material of the recording element substrate H1100, and is equivalent to the thermal conductivity of the recording element substrate H1100 material. Alternatively, it can be made of a material having an equivalent or higher thermal conductivity. Examples of the material of the support substrate H1200 include silicon (Si), aluminum nitride (AlN), zirconia, silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), molybdenum (Mo), and tungsten (W). It can be either of them. The support substrate H1200 is formed with an ink supply port H1201 (first ink supply port) for supplying ink to the recording element substrate H1100. This ink supply port is aligned with the ink supply port H1101 (second ink supply port) of the Si substrate H1108, so that ink can be supplied through these supply ports. That is, the recording element substrate H1100 is bonded and fixed to the support substrate H1200 with high positional accuracy. The support substrate H1200 has an X-direction reference H1204, a Y-direction reference H1205, and a Z-direction reference H1206, which are positioning references. As will be described later with respect to each embodiment of the present invention, a cooling liquid flow path is formed in the support substrate H1200 as a member having a cooling function.

  The recording element substrate H1100 having the above configuration is arranged in a staggered manner on the support substrate H1200 as shown in FIG. 1, and the recording width of the same color (the above-mentioned predetermined length of the ejection port array length) is wide. Is possible. For example, four recording element substrates H1100a, H1100b, H1100c, and H1100d, each having an ejection port array length of 1 inch or more in consideration of the overlapping portion, are arranged in a staggered pattern with a partly overlapped, and the width is 4 inches. Can be recorded.

  Further, the end portion of the ejection port array of each recording element substrate has a region (L) overlapping with the end portion of the ejection port array of another recording element substrate adjacent to the staggered pattern in the recording direction, As a result, a gap is prevented from being generated between the recording areas of each recording element substrate. For example, overlapping regions H1109a and H1109b are provided in the discharge port group H1106a and the discharge port group H1106b.

  As shown in FIG. 3, the electric wiring board H1300 transmits an electric signal for ejecting ink to the recording element substrate H1100, and has an opening for incorporating the recording element substrate H1100. A plate H1400 is bonded and fixed to the back surface of the electrical wiring board H1300. The electric wiring board H1300 includes an electrode terminal H1302 corresponding to the electrode H1103 of the recording element board H1100 and an external signal input terminal H1301 for receiving an electric signal from the recording apparatus main body arranged at the wiring end of the board. have. For example, the electrode H1103 of the recording element substrate H1100 and the electrode terminal H1302 of the electric wiring substrate H1300 are electrically connected to each other by a wire bonding technique using a gold wire H1303 (not shown). Is done. As a material of the electrical wiring board H1300, for example, a flexible wiring board having a two-layer structure is used, and a surface layer is covered with a polyimide film.

  As shown in FIG. 3, the plate H1400 is formed of a SUS plate having a thickness of 0.5 to 1 mm, for example. The material of the plate is not limited to SUS, and may be made of other materials having ink resistance and good flatness. The plate H1400 has an opening H1402 for receiving the recording element substrate H1100 bonded and fixed to the support substrate H1200, and is fixed to the support substrate.

  A groove formed by the opening H1402 of the plate and the side surface of the recording element substrate H1100 is filled with the first sealing agent H1304 (FIG. 1), and the electrical mounting portion of the electrical wiring substrate H1300 is sealed. The electrode H1103 of the recording element substrate is sealed with a second sealant H1305 (FIG. 1) to protect the electrical connection portion from corrosion by ink and external impact.

  Further, as shown in FIG. 3, a filter member H1600 for removing foreign matters mixed in the ink is bonded and fixed to a portion on the back side of the ink supply port H1201 in the support substrate H1200. Further, as shown in FIG. 2, the ink supply member H1500 is formed by resin molding, for example, and includes a common liquid chamber H1501 and a Z-direction reference surface H1502. The Z-direction reference plane H1502 serves to position and fix the recording element unit, and serves as the Z-direction reference for the recording head H1000.

  As shown in FIG. 2, the recording head H1000 is completed by coupling the recording element unit H1001 to the ink supply member H1500. The coupling is performed as follows. The opening of the ink supply member H1500 and the recording element unit H1001 are sealed with a third sealant H1503, and the common liquid chamber H1501 is sealed. Then, the Z-direction reference H1502 of the recording element unit H1001 is brought into contact with the Z-direction reference H1502 of the ink supply member, and is positioned and fixed by, for example, a screw H1900. The third sealant H1503 is desirably a sealant that has ink resistance, is cured at room temperature, and can withstand the linear expansion difference between different materials. The portion of the external signal input terminal H1301 of the recording element unit H1001 is bent and fixed to the back surface of the ink supply member H1501, for example (FIG. 1).

  As shown in FIG. 5, the ink jet recording apparatus M4000 according to the embodiment of the present invention includes, for example, six color recording heads corresponding to photographic image quality recording. Here, H1800Bk is black ink, H1800C is cyan ink, H1800M is magenta ink, H1800Y is yellow ink, H1800LC is light cyan ink, and H1800LM is an ink tank of light magenta ink. The recording head H1000Bk is a recording head for black ink, the recording head H1000C is for cyan ink, the recording head H1000M is for magenta ink, and the recording head H1000Y is for yellow ink. Further, the recording head H1000LC is for light cyan ink, and the recording head H1000LM is for light magenta ink. Reference numeral H1802 denotes an ink supply tube for supplying ink from each ink tank to the corresponding recording head. These recording heads H1000 are fixedly supported by the positioning mechanism and electrical contacts M4002 of the head mounting portion M4001 mounted on the recording apparatus main body M4000. These recording heads are controlled by a drive circuit (not shown) to perform recording on a recording medium.

  Note that the recording apparatus shown in FIG. 5 is a full-line type in which the recording head has ejection openings corresponding to the width of the recording medium, the recording head is fixed, and recording is performed by scanning the recording medium K1000 in the direction of the arrow. It is. On the other hand, the recording apparatus of FIG. 6 is a serial drive type recording apparatus in which a recording head is mounted on the head mounting portion M4001 and performs recording while reciprocating in the main scanning direction (carriage movement direction). It will be apparent from the following description that the present invention can also be applied to a recording head used in this serial recording apparatus.

(Embodiment 1)
In one embodiment of the present invention, the support substrate that supports the recording element substrate has a two-stage structure. As described above, the support substrate has a two-stage structure including the first support substrate and the second support substrate, whereby the second support substrate to be bonded to the recording element substrate can be downsized. Thus, the second support substrate can be manufactured at low cost and with high accuracy by a molding method. Further, the first support substrate does not require much positional accuracy of the ink supply port or the like. As a result, it is possible to employ a green sheet laminating method in which this substrate is formed by, for example, punching a green sheet into a required shape, laminating and firing, and a support substrate can be manufactured at a low cost even in a large size. Furthermore, in the present embodiment, the first support substrate can be made of a material that has a thermal conductivity that is not as high as that of the second support substrate. For example, a material that has a lower thermal conductivity than alumina can be used. According to the present embodiment, although the dimensional stability at the time of molding is excellent, it is possible to use even a material that could not be used alone because of insufficient heat dissipation, realizing a large size recording while realizing cost reduction. Even the head can prevent a decrease in dimensional accuracy during molding.

  In one embodiment of the present invention, in the two-stage structure of the support substrate, a heat pipe is provided between the first support substrate and the second support substrate. In other words, a recording head having a two-stage support substrate has a plurality of second support substrates that are downsized on one first support substrate. In this case, it is difficult to transfer the heat of one second support substrate that has received heat from the recording element substrate to the adjacent second support substrate. As a result, temperature unevenness occurs between the second support substrates, and a difference occurs in the temperature rise state of each recording element substrate mounted on the second support substrate, thereby deteriorating the recording quality due to the variation in the discharge amount. May cause problems. In order to prevent such a problem, a heat pipe is provided between the first support substrate and the back side of the second support substrate on which the recording element substrate is arranged, so that a plurality of second support substrates are provided. Temperature unevenness can be prevented from occurring. As a result, it is possible to reduce temperature unevenness between the recording element substrates disposed on the second support substrate. Since the heat pipe is disposed so as to be sandwiched between the first support substrate and the second support substrate, the heat pipe can be brought as close to the recording element substrate as the heat generation source as much as possible. Unevenness can be reduced efficiently.

  Furthermore, in one embodiment of the present invention, a cooling liquid path (cooling path) is provided inside the first support substrate. Thereby, the cooling liquid in the cooling path can efficiently receive and discharge the heat generated in the recording element substrate via the second support substrate. As a result, it is possible to appropriately suppress the temperature rise of the recording element substrate.

  FIG. 7A is a front view of the recording head according to the first embodiment of the present invention as viewed from the recording element substrate side. For the sake of simplification, the electric wiring board is not shown. 7B is a diagram schematically showing a cross-sectional surface taken along the line VIIB-VIIB in FIG. 7A, and FIG. 7C is a diagram schematically showing a cross-sectional view taken along the line VIIC-VIIC in FIG. 7A.

  As shown in these drawings, the support substrate H1200 is configured by bonding a first support substrate H1202 and second support substrates H1203a, H1203b, H1203c, and H1203d with an adhesive. Here, the first support substrate H1202 is formed by laminating and firing alumina green sheets, and the second support substrates H1203a, H1203b, H1203c, and H1203d are formed with high accuracy by molding alumina. . That is, it has a two-stage structure of one first support substrate and four second support substrates. Recording element substrates H1100a, H1100b, H1100c, and H1100d are mounted on the four second support substrates, respectively. The four recording element substrates each have a so-called staggered arrangement in which two sets of ejection opening arrays are arranged so as to partially overlap each other. The recording head of this embodiment is a so-called full-line type recording head in which ejection openings are arranged in a range corresponding to the width of the recording medium to be transported. The ink in the common liquid chamber H1501 of the recording head is an ink circulation mechanism ( (Not shown).

  As shown in the cross-sectional views of FIGS. 7B and 7C, three water paths H2004 of cooling water are formed in the first support substrate H1202 by a manufacturing method described later with reference to FIG. These water channels are connected to a circulation mechanism (not shown) for circulating cooling water provided outside the recording head. By providing the liquid path (cooling path) for the cooling liquid in the support substrate in this way, the cooling path can be disposed close to the recording element substrate that is a heat generation source, and heat generated in the recording element substrate is discharged. Can be performed efficiently.

  In addition, three heat pipes H2000 are interposed between the first support substrate H1202 and the second support substrates H1203a, H1203b, H1203c, and H1203d via an adhesive (not shown) having high thermal conductivity. It is sandwiched between. In addition, although the heat pipe H2000 is each represented as a rectangular cross section (FIG. 7C) in the figure, it actually has a flat cross section. In addition, the heat pipe H2000 is inserted into a recess formed in one or both of the second support substrates H1203a to H1203d and the first support substrate H1202. Here, when the concave portion is provided on the second support substrate side, it is possible to further promote soaking by bringing the heat pipe closer to the recording element substrate which is a heat source. On the other hand, when the concave portion is provided on the first support substrate side, the concave portion can be formed at a low cost by forming the first support substrate using a green sheet lamination method described later with reference to FIG. .

  Of these three heat pipes H2000, two heat pipes on both sides are in contact with two second support substrates (via an adhesive), and one central heat pipe is four second support substrates. And (via adhesive). That is, a heat pipe (temperature uniformizing member) in contact with each of the second support substrates provided corresponding to the individual recording element substrates is provided. Thus, the temperature can be made uniform among the plurality of second support substrates, and as a result, the temperature between the recording element substrates bonded to the respective support substrates can be made uniform. In addition, since the heat pipe is provided between the first support substrate and the second support substrate, the heat pipe can be disposed close to the recording element substrate, and the temperature equalization by the heat pipe can be efficiently performed. Can be done.

  FIG. 8 is a diagram schematically showing a procedure for manufacturing the first support substrate H1202 described above by the green sheet lamination method. As shown in the figure, this procedure is as follows: (1) First, the green sheet constituting the support substrate is composed of three sheets in this embodiment, and each is punched with a dedicated punching die. (2) Next, an adhesion liquid is applied and laminated and pressed to form a support substrate. (3) Next, the outer shape is punched out to determine the final outer shape, and (4) it is put into a heating furnace and fired. (5) Finally, surface accuracy is obtained by grinding the front and back surfaces of the support substrate.

  When the first support substrate is formed by the above-described steps, a supply port is formed before firing, and deformation such as curing shrinkage and warpage due to firing can occur, so that it can be said that the positional accuracy of the supply port is sufficient. Absent. However, with regard to cost, it can be produced at a lower cost than a product in which grooves and supply ports are additionally machined after firing. On the other hand, the second support substrate often has a more complicated ink flow path than the first support substrate, and also needs to be bonded and fixed to the ink supply port H1101 of the recording element substrate with high positional accuracy. It needs to be created with high accuracy. Although it is difficult to manufacture such four second support substrates by an integral molding method in terms of dimensional accuracy, it is a small size that is individual corresponding to the recording element substrate as in this embodiment. Can be manufactured by a molding method, and can be manufactured at low cost.

The first and second support substrates described above are made of, for example, an alumina (Al ₂ O ₃ ) material having a thickness of ₃ mm to 10 mm. The material of the support substrate is not limited to alumina, and has a linear expansion coefficient equivalent to that of the material of the recording element substrate H1100, and is equivalent to or equivalent to the thermal conductivity of the material of the recording element substrate H1100. It may be made of a material having the above thermal conductivity.

Examples of the material of the first support substrate include silicon (Si), carbon graphite, zirconia, silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), molybdenum (Mo), and tungsten (W). it can. In addition to the first support substrate material, Sumitomo Osaka Cement Zima, or a resin material with an increased filler filling rate and improved thermal conductivity (eg, Toray PPS). Can be used. As the adhesive between the support substrates, for example, an adhesive having a low viscosity, a thin adhesive layer formed on the contact surface, a relatively high hardness after curing, and ink resistance is desirable. For example, it is a thermosetting adhesive mainly composed of an epoxy resin, or an ultraviolet curing combined thermosetting adhesive, and the thickness of the adhesive layer is desirably 50 μm or less. In particular, in consideration of releasing heat from recording on the recording element substrate H1100 to the support substrate H1200 side, 10 μm or less is desirable.

  As described above, since the second support substrate is divided into a plurality of parts, it has a structure in which the temperature rise due to the recording of the recording element substrate is difficult to be transmitted to the next, and a structure for equalizing the temperature between the second support substrates is provided. Necessary. In the present embodiment, a heat pipe is sandwiched between the first support substrate and the second support substrate via an adhesive having high thermal conductivity, and the temperature rise due to recording between the recording element substrates is equalized. be able to. The heat pipe may be inserted when the first support substrate and the second support substrate are bonded, or may be mounted after various heat treatment steps of the process. From the relationship between the linear expansion coefficient of alumina and the heat pipe, it is preferable to install after the heat treatment step as much as possible.

(Embodiment 2)
The second embodiment of the present invention is a two-layer structure of the first support substrate, and is otherwise the same as the first embodiment described above.

  FIGS. 9A to 9C are diagrams mainly illustrating the first and second support substrates according to the second embodiment, and are the same as FIGS. 7A to 7C described above. It is. As shown in FIGS. 9B and 9C, the first support substrate is obtained by bonding two layers of support substrates H1202A and H1202B to each other. Specifically, the first support substrate (H1202) is formed by using two Zima-made substrates H1202A and H1202B, using Sumitomo Osaka Cement Zima material, and bonding them together to form the first support substrate. It was created.

  According to this embodiment, although the thermal conductivity of the first support substrate is somewhat lower than in the first embodiment described above, the dimensional accuracy by molding the material can be increased. Thereby, the ink flow path formed in the support substrate can be created with high accuracy, and the assemblability is improved and the cost can be significantly reduced.

(Embodiment 3)
The recording head according to the third embodiment of the present invention differs from the first embodiment described above in that the second support substrate is formed by molding a silicon carbide material as a material. The other points are the same. The silicon carbide material has a thermal conductivity of 200 W / m · K, which is higher than that of alumina, which is about 30 W / m · K. Thereby, even when the temperature of the recording element substrate rises, the amount of heat dissipated through the second support substrate can be relatively increased, and the cooling effect by the cooling path provided in the first support substrate can be improved. In combination, it is possible to further suppress the temperature rise of the head.
The heat pipe used in each of the above embodiments will be further described as follows.

  A commercially available heat pipe can be used as the heat pipe. The shape is not particularly limited as long as the contact area with the support substrate is ensured, but a flat shape in which the pipe is crushed is preferable from the viewpoint of the workability of the groove and the head structure. In addition, a material that fills the gap between the heat pipe and the support substrate has a high thermal conductivity and can be used as long as it is stable, and a silicon-based adhesive or grease can be used.

  In each of the above embodiments, a heat pipe is used as a member that is in contact with the plurality of second support substrates in common and equalizes the temperatures of the substrates. However, the application of the present invention is not limited to this member, and it goes without saying that any member may be used as long as it is a member that quickly transfers heat due to its good thermal conductivity.

  Further, the material of the support substrate described above is preferably a material having rigidity and ink resistance and good heat conduction, and a ceramic material is mainly used. Among the ceramics, alumina is relatively inexpensive and rigid, and is suitable for a long recording head in which warping and waviness of the head is likely to be a problem. In particular, an alumina substrate obtained by laminating and firing green sheets is preferable because it can be manufactured at low cost even for a complicated structure such as a recording head according to the present invention. With respect to the arrangement of the heat pipe and the cooling path with respect to the support substrate, it is preferable that the heat pipe and the cooling path be as close as possible to the recording element substrate which is a heating element. As a result, among the plurality of recording element substrates, the temperature distribution of the support substrate partially raised by the temperature rise of the recording element substrate used for recording can be equalized by the heat pipe with high heat exchange efficiency, and can be cooled by the cooling liquid. Can be. Accordingly, the heat pipe is disposed between the first support substrate and the second support substrate so as to sandwich the heat pipe, thereby correcting the thermal imbalance between the second support substrates and releasing heat to the first support substrate side. The cooling water is allowed to flow through the cooling pipe. With such a configuration, the temperature distribution in the recording head can be reduced, and the temperature rise can be suppressed. As a result, even when recording is performed at high density and at high speed, partial density unevenness and non-ejection of ink can be prevented and high quality images can be recorded at high speed.

  When only the heat pipe is installed, only the effect of soaking can be expected, but depending on the recording conditions, cooling may not be necessary, so the effect can be expected for high-definition recording. However, in the case of continuous recording at high speed, it is preferable to have a cooling structure, and one side of the heat pipe can be extended from the support substrate and connected to a cooling member such as a heat sink for cooling. In this case, it is possible to have the effect of equalizing and cooling the head.

  Note that water, ink, air, nitrogen gas, or the like can be used as the cooling liquid, that is, the cooling medium. In particular, when a temperature-controlled medium is circulated and used, temperature management and control are facilitated. Further, when the cooling path is divided into a plurality of parts, the temperature of the recording head can be finely controlled according to the direction in which the coolant flows, the number of lines used, and the like.

  FIG. 10 is a diagram for explaining a comparison between a recording head according to an embodiment of the present invention and a conventional recording head without a heat pipe and a cooling path, based on the recording head temperature (increase) at the time of recording 50 sheets. is there. Here, of the four chips, the used recording element substrates are only the substrates H1100a and H1100b, and the substrates H1100c and H1100d are not used. As shown in FIG. 10, in the case of the conventional recording head, the recording element substrates H1100a and H1100b reached a high temperature after recording about 50 sheets, and the temperature continued to rise and non-ejection occurred. On the other hand, in the first embodiment of the present invention, the temperature rise of the recording head is substantially the same as the used recording element substrates H1100a and H1100b and the unused recording element substrates H1100c and H1100d, and the temperature is made uniform. Yes. By this equalization, the temperature rise is saturated at about 50 sheets, and the amount of temperature rise is suppressed to about half that of the conventional recording head. Further, no discharge occurred even when recording was continued. Next, in the recording head of the second embodiment, the saturation temperature is slightly higher than that in the first embodiment, but the temperature difference in the length direction of the recording head can be suppressed to an extent that there is no problem. The temperature rise (ΔT) varies depending on the heat transport amount of the heat pipe, the shape of the cooling path, the flow rate of the coolant, and the temperature, but it should be set to the optimum conditions according to the specifications of the recording head to be used. Of course.

(Embodiment 4)
In the fourth embodiment of the present invention, the heat pipe is disposed between the first support substrate and the second support substrate in the first to third embodiments described above, whereas the heat pipe is disposed inside the first support substrate. It is related with the form provided in. 11A and 11B are cross-sectional views of the ink jet recording head according to the fourth embodiment. FIG. 11A is a vertical cross-sectional view, and FIG. 11B is a cross-sectional view taken along the line XIB-XIB in FIG. The support substrate H1200 has a two-stage structure in which a first support substrate H1202 and a second support substrate H1203 (H1203a, H1203b, H1203c, and H1203d) are bonded together with an adhesive. The first support substrate H1202 is made by laminating and firing alumina (Al ₂ O ₃ ) green sheets, as will be described later with reference to FIG. 12, and the second support substrate H1203 is made by molding alumina with high accuracy. Made to. On the support substrate H1200, four recording element substrates H1100a, H1100b, H1100c, and H1100d are mounted in a staggered arrangement so that the end portions overlap each other in the recording direction.

  A space H2001 for installing a heat pipe H2000 is formed in the first support substrate H1202. The cross section of the groove for installing the heat pipe is 4.2 mm wide and 2.2 mm deep, and the flat heat pipe H2000 having a cross sectional shape of 4 mm wide and 2 mm thick has a gap between the space H1201 and the silicon adhesive. It is fixed to the support substrate H1202 by filling with. In addition, an ink supply port H1201 is formed in the second support substrate H1203.

FIG. 12 is a diagram schematically showing a process of manufacturing the first support substrate H1202 by the green sheet lamination method.
(1) A plurality of green sheets constituting the first support substrate H1202 are each punched into a predetermined shape (such as an opening of a supply unit communicating with the ink supply port H1201) with a dedicated punching die. (Die punching process)
(2) Next, a plurality of green sheets are applied by applying an adhesion liquid and pressed to form a first support substrate H1202 having an insertion space for the heat pipe H2000. (Sheet lamination process)
(3) Next, the outer shape of the assembled laminated product is punched to determine the final outer shape. (Laminated product cutting process)
(4) Next, the laminated product whose outer shape is determined is put into a heating furnace and fired. (Baking process)
(5) Next, a predetermined surface accuracy is obtained by grinding the front surface and the back surface of the laminated product after firing.

(Grinding process)
The first support substrate H1202 manufactured through each of these steps is subjected to a baking step after forming a supply portion opening or the like before baking, and therefore it can be said that the positional accuracy with respect to the ink supply port H1201 is not necessarily sufficient. Absent. However, the above-described manufacturing method can be manufactured at a very low cost compared to the case where the space H1201 for storing the heat pipe H2000 and the supply opening are additionally processed after firing. In this way, the support substrate can be composed of the first support substrate using the green sheet laminating method and the second support substrate made with high precision by the molding method, thereby providing a cheaper head. can do.

  Further, regarding the positional accuracy of the ink supply port H1201, the second support substrate H1203 is manufactured with high accuracy by a molding process, and is bonded and fixed to the first support substrate H1202 with high positional accuracy. Thereby, an ink jet recording head having substantially no problem in positional accuracy with respect to the ink supply port H1101 of the recording element substrate H1100 can be created.

  According to this embodiment, by providing the heat pipe H2000 in the support substrate H1200, the temperature of the ink jet recording head, in particular, the temperature between the recording element substrates H1100 can be made uniform.

(Embodiment 5)
The fifth embodiment of the present invention is a form in which a heat pipe is provided in the first support substrate, as in the fourth embodiment. The difference from the fourth embodiment is that the same is used for cooling in the first support substrate. This is to provide a flow path (cooling path). FIG. 13 is a schematic cross-sectional view of the inkjet recording head of the fifth embodiment. FIG. 13A is a longitudinal section, and FIG. 13B is a sectional view taken along line XIIIB-XIIIB in FIG. As shown in these drawings, a heat pipe H2000 and a cooling medium flow path H2002 are formed in the first support substrate H1202.

  FIG. 14 is a schematic diagram showing a cross section of only the first support substrate H1202. The first support substrate H1202 is formed by a green sheet laminating method using five alumina green sheets. Three holes are independently formed in the first support substrate H1202, and a space H2001 for installing the heat pipe H2000 is formed. Three additional holes are independently formed in parallel to the holes, and the cooling medium can be flowed by forming a flow path H2002 by these holes. The shape of the space for installing the heat pipe and the shape of the heat pipe to be used are the same as in the fourth embodiment described above. The heat pipe H2000 is fixed to the first support substrate H1202 by filling a gap between the heat pipe H2000 and the wall of the hole with a silicon adhesive. In the present embodiment, the cross section of the flow path H2002 has a width of 3 mm and a depth of 2 mm. The flow rate of the cooling liquid was about 20 ml / min to 100 ml / min. Of course, the flow rate may be any flow rate suitable for the conditions depending on the recording execution conditions and the recording head specifications.

  As the heat pipe H2000 of the fourth and fifth embodiments, a commercially available heat pipe can be used as in the first embodiment. From the viewpoint of increasing the contact area with the first support substrate H1202, it is preferable to use a shape in which the cross section of the pipe is flat. The material that fills the gap between the heat pipe H2000 and the hole wall of the first support substrate H1202 can be used as long as it has a high thermal conductivity and is stable, and a silicon-based adhesive or grease can be used. .

  As in the first embodiment, the material of the first support substrate H1202 in the fourth and fifth embodiments is preferably a material having rigidity and ink resistance and good heat conduction, and a ceramic material is mainly used. Among ceramic materials, alumina is relatively inexpensive and rigid, and is optimal as a material for a long recording head in which warping or waviness of the recording head is likely to be a problem. In particular, an alumina substrate obtained by laminating and firing green sheets is preferable because it can be manufactured at low cost even for a complicated structure such as that of the present embodiment. In addition, the recording head of this embodiment has a heat insulating layer as compared with a comparative example (a structure in which grooves and supply ports are formed by grinding after baking and a structure in which three plates are bonded with an adhesive). Therefore, it is not necessary to use an adhesive, which is preferable because the cooling and soaking of the head is promoted.

  As for the arrangement of the heat pipes H2000 and the cooling paths H2002 in the first support substrate H1202, it is desirable that the heat pipes H2000 and the cooling paths H2002 be as close as possible to the recording element substrate H1100 serving as a heat generation source. Further, among the plurality of recording element substrates, the temperature distribution of the support substrate H1200 partially raised by the temperature rise of the recording element substrate H1100 used for recording is soaked by the heat pipe H2000 with high heat exchange efficiency, and the cooling liquid Therefore, it is necessary to be able to perform cooling. Therefore, the recording head of this embodiment in which the heat pipe H2000 is arranged as close as possible to the recording element substrate H1100 side in the support substrate H1200 and the cooling path H2002 is arranged with the partition layer interposed therebetween is the first implementation. The cooling efficiency is superior to that of the recording head of the form.

  With such a configuration, the distribution of temperature differences in the head is reduced, and the temperature rise can be suppressed. Therefore, even when high-speed recording is performed at high density, partial density unevenness and non-ejection can be prevented, and high-quality images can be recorded at high speed.

  If only the heat pipe H2000 is installed, only the effect of soaking can be expected, but depending on the recording execution conditions, cooling may not be necessary. However, when performing continuous recording at high speed, it is also necessary to have a cooling method. Thus, a more efficient cooling effect can be acquired by providing both the structure of the heat pipe H2000 and the flow path H2002 for cooling.

  As the cooling medium, water, ink, air, nitrogen gas, or the like can be used. Especially when a temperature-controlled medium is circulated and used, temperature management and control are facilitated. Further, when the cooling path is divided into a plurality of sections, the head temperature can be finely controlled depending on the flow direction of the cooling liquid and the number of the cooling paths used.

  Using the inkjet recording heads of the fourth and fifth embodiments, high-speed continuous recording was performed by driving only two of the four recording element substrates. As a result, the substrate temperature of the recording element substrate used for recording and the recording element substrate not used is equalized so that the temperature between the recording element substrates such as a conventional recording head is the same. There was no imbalance.

(Embodiment 6)
Similarly to the third embodiment, the second support substrate H1203 of the fourth and fifth embodiments can be formed by molding using a silicon carbide material.

  The silicon carbide material has a thermal conductivity of 200 W / m · K, which is higher than that of alumina, which is about 30 W / m · K. Therefore, even when the temperature of the recording element substrate rises, the heat can be dissipated through the second support substrate H1203, so that the temperature rise of the recording head can be further suppressed.

  FIG. 15 is a diagram showing a circulation configuration of the coolant according to the first and fifth embodiments described above. As shown in the figure, the cooling medium is sent to the cooling medium inlet of the recording head H1000 by the pump H3101, and returns to the thermostatic chamber H3000 again through the cooling path in the recording head described above. The control device H3100 of the recording apparatus monitors the flow rate of the cooling medium via the flow meter H3102, and monitors the inlet temperature, outlet temperature, and recording head temperature of the recording head. The control device H3100 adjusts the flow rate, adjusts the temperature of the thermostatic chamber, and the like according to the recording conditions, the environmental temperature, and the like. When ink, that is, a recording liquid is used as the cooling medium, the number of tanks can be reduced as compared with the case where another medium is used, and the size of the recording apparatus can be reduced.

  As described above, according to each embodiment of the present invention, the case where the first support substrate is formed by the green sheet lamination method and incorporates the cooling pipe in an integrated structure, and the two plates are bonded together. Any of the cases where the cooling pipe is built can be selected. By adhering the first support substrate and the second support substrate and using them as a support substrate for the recording head, a heat pipe or a cooling pipe can be configured at a predetermined position, and the positional accuracy of the ink supply port is sufficiently secured. Can be manufactured at low cost. A heat pipe or a cooling path can be arranged as a heat exchanging means as close as possible to the recording element substrate as a heat source. At the same time, the maximum contact area with the second support substrate, which is heated by the heat generated by the recording element substrate, can be ensured to the maximum, and the heat exchange efficiency is remarkably improved, and the recording head can be effectively cooled and soaked.

1 is an external perspective view of a recording head according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the recording head illustrated in FIG. 1. FIG. 2 is an exploded perspective view of a recording element unit constituting the recording head shown in FIG. FIGS. 4A and 4B are a perspective view and a cross-sectional view, respectively, illustrating a recording element substrate constituting the recording element unit. 1 is a diagram illustrating an ink jet recording apparatus according to an embodiment of the present invention. It is a figure which shows the inkjet recording device which concerns on other embodiment of this invention. (A), (b), and (c) are respectively a front view, a VIIB-VIIB sectional view, and a VIIC-VIIC sectional view showing the arrangement of the cooling system and the heat pipe in the recording head shown in FIG. It is a figure explaining the manufacturing process of the support substrate of a recording head by the green sheet lamination method which concerns on one Embodiment of this invention. (A), (b), and (c) are a front view, an IXB-IXB line sectional view, and an IXC-IXC line, respectively, showing the arrangement of a cooling system and a heat pipe in a recording head according to another embodiment of the present invention. It is sectional drawing. FIG. 6 is a diagram for explaining a comparison of temperature rise states of a recording head according to an embodiment of the present invention and a conventional recording head. It is a cross-sectional schematic diagram of the recording head which concerns on the 4th Embodiment of this invention. It is a figure which illustrates typically the manufacturing process of the 1st support substrate by the green sheet lamination method. FIG. 9 is a schematic cross-sectional view of a recording head according to a fifth embodiment of the invention. FIG. 14 is a diagram schematically illustrating only a first support substrate of the recording head of FIG. 13. It is a figure which shows the structure of the cooling system which concerns on one Embodiment of this invention.

Explanation of symbols

H1000 recording head H1001 recording element unit H1002 ink supply unit H1100, H1100a to H1100d recording element substrate H1101 ink supply port H1102 electrothermal conversion element H1200 support substrate H1201 ink supply port H1202, H1202A, H1202B first support substrate H1203, H1203a to H1203d Second support substrate H1501 Common liquid chamber H2000 Heat pipe H2004 Cooling path

Claims (13)

An inkjet recording head,
A plurality of recording element substrates including thermal energy generating elements for ejecting ink;
A first support substrate;
A plurality of second support substrates supported by the first support substrate, each supporting the recording element substrate;
A temperature equalizing member disposed between the first support substrate and the second support substrate or in the first support substrate;
An ink jet recording head characterized by comprising:   The inkjet recording head according to claim 1, wherein the temperature equalizing member is a heat pipe.   The inkjet recording head according to claim 1, further comprising a member having a cooling function in the first support substrate.   The inkjet recording head according to claim 3, wherein the member having the cooling function is a cooling path for flowing a cooling liquid.   5. The ink jet recording head according to claim 1, wherein a thermal conductivity of the second support substrate is larger than a thermal conductivity of the first support substrate. 6.   The inkjet recording head according to claim 1, wherein the second support substrate is made of a ceramic material.   The inkjet recording head according to claim 1, wherein the first support substrate is formed by laminating green sheets and firing the laminated green sheets.   8. The ink jet recording head according to claim 1, wherein the second support substrate is formed by a molding method.   The ink jet recording head according to claim 1, wherein the plurality of recording element substrates are arranged in a staggered pattern.   An ink jet recording apparatus comprising the ink jet recording head according to claim 1 and performing recording by discharging ink from the recording head.   An ink jet recording apparatus comprising: the ink jet recording head according to claim 4; and means for flowing a liquid through a cooling path provided in the first support substrate.   The inkjet recording apparatus according to claim 11, further comprising a control device that controls a means for flowing the liquid to suppress a temperature rise of the inkjet recording head.   The ink jet recording apparatus according to claim 11, wherein an ink is used as the liquid that is flowed for the cooling.

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