Inkjet Head and Inkjet Recording Apparatus

Abstract

To provide an ink jet head capable of more easily improving uniformity of a temperature near a nozzle opening, and an ink jet recording apparatus.SOLUTION: An ink jet head (10) comprises: a head chip (11) that has a bottom surface provided with a plurality of nozzle openings; a thermally conductive member (16) that is positioned around the bottom surface of the head chip (11) and brought into contact with the head chip (11); and a heating part (17) for heating the thermally conductive member (16).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an inkjet head and an inkjet recording apparatus.

Background Art

[0002] In an inkjet head having nozzles, when ejecting ink from the nozzles and landing it on a recording medium to record an image, a film, a structure, etc., by keeping the ejection conditions of the ink from a large number of nozzles uniform, it becomes possible to record a uniform image or the like. In particular, the viscosity and fixing time of the ink are greatly affected by the temperature of the ink. Therefore, in an inkjet head, there is a technique of controlling the heating not only of the supplied ink but also of the vicinity of the nozzle opening.

[0003] Conventionally, in a head chip provided with nozzle openings, due to the positional relationship between the array of a large number of nozzle openings and the heating part, and the ink ejection state of each nozzle, etc., the heating and heat dissipation conditions vary depending on the position, and a uniform temperature cannot be obtained by simply heating uniformly. In contrast, Patent Document 1 discloses a technique of arranging a plurality of heating elements and individually controlling the operation according to the difference in the driving frequency of each nozzle. Further, Patent Document 2 discloses a technique having a heating part in a shape in which more heat is supplied near both longitudinal ends of a head chip with a large heat dissipation amount.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, assuming individual control of a plurality of heating elements increases the cost and labor accordingly. Further, in a configuration where the heating amount varies depending on the location uniformly, there is a problem that it is difficult to cope with a non-uniform temperature distribution caused by fluctuations in conditions other than static factors such as the nozzle arrangement.

[0006] An object of the present invention is to provide an inkjet head and an inkjet recording apparatus capable of easily enhancing the uniformity of the temperature near the nozzle opening.

Means for Solving the Problems

[0007] To achieve the above object, the invention according to claim 1 is a head chip having openings of a plurality of nozzles on one surface, a heat conduction member located around the one surface of the head chip and in contact with the head chip, a heating unit that heats the heat conduction member, and includes In a plan view of the head chip as seen from a direction perpendicular to the one surface, The heat conduction member has voids along the longitudinal direction of the head chip at positions on both sides near the center in the vicinity of the center, which are sandwiching in a direction perpendicular to the longitudinal direction, and facing the vicinity of the center on each side, in the longitudinal direction of the head chip along a plurality of and has no voids along the direction perpendicular to the longitudinal direction of the head chip extending along the outer edge of the head chip along at the portion and is an inkjet head characterized by this.

[0008] Further, the invention according to claim 2 is, in the inkjet head according to claim 1 record wherein the heat conduction member is in annular contact with the outer periphery of the one surface.

[0009] Further, the invention according to claim 3 is, in the inkjet head according to claim 2 wherein the heating unit is in annular contact with the heat conduction member outside the outer periphery of the one surface.

[0011] Further, the invention according to claim​​​4 The invention described in claim 1 to 3 In the inkjet head according to any one of The heating unit is characterized in that the heating amount increases from the center to both ends in the longitudinal direction of the heat conduction member.

[0012] Also, in the claim 5 The invention described in claim 1 to 4 In the inkjet head according to any one of It includes a measuring unit for measuring the temperature of the heat conduction member, The measuring unit is characterized in that it is positioned to perform measurement at the center in the longitudinal direction of the head chip.

[0013] Also, in the claim 6 The invention described in claim 1 to 5 In the inkjet head according to any one of The head chip includes an individual supply channel for sending ink to each of the plurality of nozzles, and a recovery channel for recovering ink from the middle of the individual supply channel, The recovery channel has an individual recovery channel that branches from each of the plurality of individual supply channels, and a common recovery channel where the plurality of individual recovery channels merge, The common recovery channel is characterized in that it extends along the longitudinal direction of the head chip.

[0014] Also, in the claim 7 The invention described in claim is Claim 1 to 6 An inkjet recording apparatus having an inkjet head according to any one of

Advantages of the Invention

[0015] According to the present invention, there is an effect that the uniformity of the temperature near the nozzle opening in the inkjet head can be easily improved.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described based on the drawings. FIG. 1 is a diagram for explaining the configuration related to ink ejection including the inkjet head 10 of this embodiment. FIG. 1(a) is a view of the inkjet head 10 seen from the front side (X direction), and FIG. 1(b) is a view of the inkjet head 10 seen from the bottom side (-Z direction).

[0018] The inkjet head 10 is attached to an inkjet recording apparatus to eject ink. The inkjet head 10 includes a head chip 11, a manifold 12, a holding part 13, an inflow pipe 14, a discharge pipe 15, a heat conduction member 16, a heating part 17, and the like. Further, the filter chamber 20 is located between the ink tank that supplies ink from the outside and the inflow pipe 14. A drive substrate 30 is connected to the inkjet head 10. The holding part 13 is fixed to the carriage 40.

[0019] The head chip 11 has a plurality of nozzles 1131 (see FIG. 2), and the bottom surface (-Z direction, one surface) shown in FIG. 1(b) is a nozzle opening surface on which a plurality of nozzle openings for discharging ink are arranged. A large number of the nozzles 1131 are arranged at each position in the longitudinal direction (Y direction). The nozzles 1131 may be arranged in a one-dimensional array or a two-dimensional array along the Y direction. The arrangement of the nozzles 1131 may be such that there are a plurality of one-dimensional nozzle rows arranged in the Y direction at different positions in the X direction. Since the size of the opening of the nozzle 1131 is extremely small compared to the size of the head chip 11, illustration is omitted in each figure below FIG. 1 except for FIG. 2 which is an enlarged view.

[0020] The manifold 12 is joined to the head chip 11, has an ink flow path for distributing the supplied ink to each nozzle 1131, and collecting and discharging the ink that has not been distributed to the nozzle 1131 or discharged from the nozzle 1131. An ink inflow pipe 14 and an ink discharge pipe 15 are connected to the upper part (+Z side) of the manifold 12. Ink flows into the inflow pipe 14 from the filter chamber 20. Further, a drive substrate 30 that outputs signals and power is connected to the upper part (+Z side) of the manifold 12, and is electrically connected to wiring that leads to a pressure mechanism (drive unit), not shown, located along an individual ink flow path (individual supply flow path 1111, see FIG. 2) corresponding to each nozzle 1131. Note that, separately from the manifold 12 (flow path substrate) having the above-described flow path structure, a wiring substrate having wiring for driving the head chip 11 may be laminated, but here it is described together as the manifold 12.

[0021] The holding part 13 fixes and holds the head chip 11 and the manifold 12, and is fixed and supported to the carriage 40 by screws or the like at both ends in the Y direction. Here, the holding part 13 has an opening on the bottom surface side, and the nozzle opening surface of the head chip 11 is exposed from the opening. Also, the connection part between the inkjet head 10 and the drive substrate 30 may be located inside the housing-shaped holding part 13. The holding part 13 may be made of an aluminum alloy, a magnesium alloy, etc., or may be made of a plastic resin, or may be a combination thereof.

[0022] The heat conduction member 16 is a separate component from the head chip 11 and the manifold 12, and may be a part of the holding part 13, such as a bottom plate. Alternatively, the heat conduction member 16 may be laminated and attached to the bottom plate of the holding part 13. Here, the heat conduction member 16 means a member having a higher thermal conductivity compared to these, particularly the other parts of the holding part 13. The heat conduction member 16 is, for example, a film or a thin plate of aluminum (pure aluminum), and may have an oxide film on its surface that is thin compared to the thickness of the heat conduction member 16 due to its characteristics. The heat conduction member 16 surrounds and contacts the head chip 11 in a ring shape around its bottom surface, and is thermally coupled to the head chip 11. The contact here means that at least partially, the interfaces are overlapping at the same position in terms of design. In reality, there are non-contact parts (for example, a separation of about 1 to 100 μm) depending on the surface state, the forming accuracy of each surface, and the assembly accuracy, etc. If such parts are left as voids, the thermal conductivity will be significantly reduced by air, so it may include cases where they are joined via a thermally conductive bonding material or filler (for example, epoxy resin). In this embodiment, the heat conduction member 16 contacts the entire circumference of the head chip 11. When the ink resistance of the heat conduction member 16 is low, etc., a protective film may be further provided on the exposed surface of the heat conduction member 16. The size of the heat conduction member 16 is here substantially the same as the bottom surface of the holding part 13.

[0023] The heating unit 17 surrounds and contacts the periphery (outer circumference) of the heat conduction member 16 in an annular shape to heat the heat conduction member 16. The heating unit 17 is, for example, a high-resistance metal wire (heating wire) that generates heat when energized and is located on the surface or inside of an insulator such as a resin sheet. When the heat conduction member 16 or the holding unit 13 is an insulator or has at least an insulating layer (film) on its surface, the heating wire may be in direct contact with these without passing through an insulator. The heating wire may be arranged in an appropriate density and contact area by meandering or the like according to the desired heat generation amount, temperature conditions (such as the allowable temperature of the heating wire), and the size of the holding unit 13. The heating unit 17 is located surrounding the side surface (including the front and back surfaces) in contact with the bottom surface of the holding unit 13 to heat the heat conduction member 16 together with the holding unit 13. The heating unit 17 may be adhered to the heat conduction member 16 and the holding unit 13 with a heat-resistant adhesive member, for example, polyimide. When the heat conduction member 16 is smaller than the bottom surface of the holding unit 13, the resin sheet or the like of the heating unit 17 may wrap around to the bottom surface side of the holding unit 13 and contact the heat conduction member 16. Conversely, when the heat conduction member 16 is larger than the bottom surface of the holding unit 13, the heat conduction member 16 may wrap around to the side surface side of the holding unit 13.

[0024] A thermistor 18 (measurement unit) is located on the surface or inside of the heat conduction member 16 or near the bottom surface of the holding unit 13. The thermistor 18 measures the temperature near the head chip 11 and outputs measurement data via the drive substrate 30. The thermistor 18 is not particularly limited, but is located near the center of the head chip 11 in the longitudinal direction (Y direction). Although the actual temperature distribution may be asymmetric in the longitudinal direction with a difference (bias) between both ends of the head chip 11, by arranging the thermistor 18 at the center, the measured value is less likely to be greatly affected by such temperature bias.

[0025] With the above configuration, the heat transferred from the heating unit 17 to the heat conduction member 16 quickly diffuses within the heat conduction member 16, and the head chip 11 is heated substantially evenly from the surroundings. The heat of the inkjet head 10 is transferred to the ink, the surrounding air, and the carriage 40. Among these, the heat conductivity of the carriage 40 is significantly high. Therefore, particularly when the temperature of the carriage 40 is low, the amount of heat radiated from the inkjet head 10 to the carriage 40 increases from both ends where the inkjet head 10 contacts the carriage 40. In the inkjet head 10 of the present embodiment, regardless of the locality and anisotropy of heat radiation, the temperature unevenness around the head chip 11 is reduced by the heat conduction of the heat conduction member 16.

[0026] The filter chamber 20 allows the ink supplied from an external ink tank and passing through the inflow pipe 14 to flow into the inkjet head 10. The ink flowing into the filter chamber 20 passes through the filter in the filter chamber 20 to remove foreign substances and the like, and then is sent to the inflow pipe 14. Here, the filter chamber 20 has an ink discharge path through which the ink flowing out from the discharge pipe 15 passes, and the outlet of the ink discharge path (one end opposite to the side connected to the discharge pipe 15) is connected to the ink flow path to the ink tank. The ink supplied to the filter chamber 20 includes the ink returned to the ink tank via the discharge pipe 15. That is, the ink that did not flow out from the nozzles 1131 in the inkjet head 10 can circulate among the ink tank, the filter chamber 20, and the inkjet head 10.

[0027] The drive substrate 30 has electrical wiring and signal wiring for inputting the power output from the power supply unit of the inkjet recording apparatus and the drive control signal of the inkjet head 10 output from the control unit to the inkjet head 10, respectively. The drive substrate 30 is connected to, for example, the connection terminals on the upper surface side of the manifold 12 and is connected to the wiring (not shown) in the inkjet head 10. Note that the filter chamber 20 and the drive substrate 30 may be included in the inkjet head 10 or may be externally configured to be separately attached.

[0028] The carriage 40 supports the inkjet head 10 and is fixed at a predetermined position facing the conveyance path (recording medium) of the recording medium to be imaged during the recording operation by the inkjet head 10. Further, when the recording operation is not performed, for example, during a maintenance operation, the carriage 40 can move the position of the inkjet head 10 to separate it from the conveyance path from a predetermined position. Note that when the set temperature of the head chip 11 is high and the temperature of the carriage 40 is likely to be relatively low according to the type of desired ink or the like, the inkjet recording apparatus may have a mechanism for heating and adjusting the carriage 40 separately from the heating unit 17.

[0029] FIG. 2 is a cross-sectional perspective view for explaining the ink flow path in the inkjet head 10. This cross-section is perpendicular to the Y direction and is a plane including one nozzle 1131.

[0030] The ink flowing into the inkjet head 10 from the inflow pipe 14 flows from the common supply flow path 121 in the manifold 12 to the common flow path 122 located near the bottom of the manifold 12, where the upper surface of the head chip 11 serves as one wall surface (bottom surface). A plurality of inlets 1111a are arranged side by side on the bottom surface (upper surface of the head chip 11) of the common flow path 122, each leading to an individual supply flow path 1111 of the head chip 11. Here, four nozzle rows extending in the Y direction are provided at different positions in the X direction, and the positions of all the inlets 1111a (i.e., nozzles 1131) are different in the Y direction. The ink that does not flow into the individual supply flow path 1111 flows directly into the common discharge flow path 123 and is discharged from the discharge pipe 15.

[0031] The head chip 11, here, has a first substrate 111, a second substrate 112, and a third substrate 113 laminated thereon. The first substrate 111 has the above-mentioned individual supply channels 1111 and a common recovery channel 1112. The second substrate 112 is provided with an ink channel 1121 communicating with the individual supply channel 1111 and an individual recovery channel 1122. The third substrate 113 is a nozzle substrate having nozzles 1131 communicating with the ink channel 1121. The common recovery channel 1112 and the individual recovery channel 1122 constitute the recovery channels of this embodiment. Also, the ink channel 1121 is included in the individual supply channels of this embodiment.

[0032] For the ink flowing into the individual supply channel 1111, pressure fluctuations are imparted by deforming the wall surface of the individual supply channel 1111 (which may be a part thereof) by a pressurizing mechanism (not shown). The ink is sent to the nozzles 1131 through the ink channel 1121 in response to this pressure fluctuation and is extruded from the openings thereof, and ink droplets of a liquid volume corresponding to the pattern and magnitude of the pressure fluctuation are separated and ejected. For the wall surface fluctuation, for example, an electromechanical conversion element such as a piezo element is used, and the ejection is controlled by applying a drive voltage waveform pattern to the electromechanical conversion element.

[0033] At the lowermost part of the ink channel 1121, the individual recovery channels 1122 having the upper surface of the third substrate 113 as one wall surface branch to both sides in the X direction. The individual recovery channels 1122 bend in the Z direction and penetrate the second substrate 112, and merge into two of the three common recovery channels 1112 of the first substrate 111, respectively. The common recovery channels 1112 each extend along the Y direction and communicate with the discharge pipe 15 near the ends. Note that the discharge pipe 15 communicating with the common discharge channel 123 and the discharge pipe 15 communicating with the common recovery channel 1112 may be separate, or may merge before finally flowing into an external ink tank.

[0034] Even when ink is not ejected from the nozzles 1131, the ink within the inkjet head 10 is supplied and recovered (discharged) such that the ink flows from the ink flow path 1121 to the common recovery flow path 1112 at a predetermined average flow velocity (flow rate) through each individual recovery flow path 1122 and the common discharge flow path 123. Accordingly, the flow velocity of the ink in the common recovery flow path 1112 also becomes a generally fixed velocity. When there is a bias in the temperature of the head chip 11 and the manifold 12 around the ink, since the flowing ink promotes the heat flow, the temperature is likely to be smoothed in the Y direction following this ink flow.

[0035] That is, in the configuration of the inkjet head 10 described above, even when there is a bias in the heat generation of the head chip 11 due to the driving conditions of the inkjet head 10 or the like, or when there is a bias in the heat dissipation to the outside due to the temperature difference between the carriage 40 and the outside air, the heat conduction member 16 quickly transfers heat so as to eliminate the temperature bias of the head chip 11, making it difficult for a temperature bias to occur in the head chip 11.

[0036] [Modification Example 1] FIG. 3 is a diagram for explaining Modification Example 1 of the inkjet head 10. As described above, ideally, the periphery of the head chip 11 has a uniform temperature due to the heat conduction member 16. However, since the thermal conductivity of the actual heat conduction member 16 is finite, it is difficult to achieve complete uniformity. In particular, when the temperature of the carriage 40 with high thermal conductivity is low, the heat dissipation amount from both ends significantly increases, and the temperatures at both ends tend to be slightly lower than that at the center. Therefore, in the inkjet head 10 of the first modification, in addition to the heat conduction member 16, the heating unit 17 performs a heating (heat generation) operation such that the heating amount increases from the center toward both ends in the Y direction. Such non-uniform heating may be obtained simply by arranging heating wires so that the heating amount at both ends increases, or may be obtained by drive control that varies the current, voltage, or operation time separately between both ends and the central portion, that is, by varying the power consumption (heat generation) amount. As shown in FIG. 3, the heat generation amount may continuously decrease at the center, or may change in a stepped manner in two or more steps. By adding this configuration, the temperature around the head chip 11 due to the heat conduction member 16 can be made closer to uniform.

[0037] [Second and Third Modifications] FIG. 4 is a bottom view showing a second modification (FIG. 4(a)) and a third modification (FIG. 4(b)) of the inkjet head 10. As described above, instead of or in addition to reducing the heating amount of the heating unit 17 near the center in the Y direction, in this inkjet head 10, a gap portion 161 is provided parallel to the head chip 11, that is, along the Y direction, near the center of the heat conduction member 16 in the Y direction. The inside of the plurality of gaps (through holes of the heat conduction member 16) of the gap portion 161 is air, that is, the thermal conductivity is much smaller than that of the heat conduction member 16. Therefore, in this portion, the heat of the heating unit 17 does not reach the head chip 11 directly but reaches it by detouring through the gap portion 161. Therefore, in particular, when the heat conduction member 16 is (partially) the bottom plate of the holding portion 13 or the like, the heating amount near the center of the head chip 11 in the Y direction is effectively reduced according to the finiteness of the thermal conductivity. As a result, the overall temperature unevenness of the head chip 11 is reduced in balance with the magnitude of heat dissipation at both ends.

[0038] On the other hand, depending on the relationship between the size and thermal conductivity of the heat conduction member 16 and the amount of heat radiated to the carriage 40, contrary to the above-described Modification 2, it is also conceivable to provide a gap 161a between the contact positions of both ends in the Y direction of the heat conduction member 16 and the holding portion 13. Thereby, while suppressing direct heat from flowing to the carriage 40 from the vicinity of the contact positions between the heat conduction member 16 and the vicinity of both ends in the Y direction of the head chip 11, both side surfaces in the X direction of the heat conduction member 16 are heated substantially evenly. Therefore, the influence of the temperature drop on both ends in the Y direction rather than the gap 161a is less likely to be transmitted to the vicinity of both ends in the Y direction of the head chip 11, and the temperature drop of the head chip 11 can be reduced.

[0039] [Modification 4] FIG. 5 is a front view for explaining Modification 4 of the inkjet head 10. In the inkjet head 10 of this Modification 4, the heating portion 17b does not completely cover the periphery of the head chip 11 and the manifold 12, and there is a break near the center in the Y direction. As described above, since the temperature is more likely to drop due to heat radiation to the carriage 40 near both ends than near the center in the Y direction of the head chip 11, the balance between heating and heat radiation may be achieved by heating the vicinity of the center from both sides via the heat conduction member 16, thereby reducing the temperature unevenness of the head chip 11.

[0040] In any of the modified examples, the temperature unevenness in the actual head chip 11 is determined according to the outside air temperature (room temperature), the temperature of the carriage 40, the usage frequency of each nozzle 1131, and the like. When the temperature inside the room where the inkjet recording apparatus (inkjet head 10) is located is high and the nozzle 1131 is used at a high frequency for a long time, the temperature of the carriage 40 also rises. Therefore, the heat dissipation to the carriage 40 becomes small, and there may be cases where the temperature gradient disappears or rather the temperature of the carriage 40 becomes higher. In Modified Example 3, since the heat exchange with the carriage 40 is suppressed, it is hardly affected by the temperature of the carriage 40. On the other hand, in the case of other examples, when the temperature of the carriage 40 rises stably, the temperature of the entire heat conduction member 16 also tends to rise as a whole, so large temperature unevenness is less likely to occur. Also, in any case, the heating operation of the heating unit 17 may be adjusted by the control operation of the control unit of the inkjet recording apparatus to be adjusted to an appropriate temperature range.

[0041] As described above, the inkjet head 10 of the present embodiment includes a head chip 11 having a plurality of nozzle openings on one surface (bottom surface), a heat conduction member 16 located around the bottom surface of the head chip 11 and in contact with the head chip 11, and a heating unit 17 that heats the heat conduction member. In this way, by increasing the thermal conductivity around the head chip 11 by a heat flow through the heat conduction member 16 having a higher thermal conductivity than the conventional holding portion 13 (and other parts), temperature unevenness that is likely to occur due to differences in local conditions such as heat dissipation to the carriage 40 is reduced. Therefore, in the inkjet head 10, the uniformity of the temperature near the nozzle opening can be more easily enhanced.

[0042] Also, the heat conduction member 16 is in annular contact with the outer periphery of the bottom surface of the head chip 11. That is, since the entire head chip 11 is surrounded and contacted by the heat conduction member 16, the temperature unevenness of the entire head chip 11 can be more reliably reduced.

[0043] Further, the heating unit 17 is in annular contact with the heat conduction member 16 outside the outer periphery of the bottom surface of the head chip 11. That is, the heat of the heating unit 17 is not directly applied to the head chip 11, but is transmitted to the head chip 11 via the heat conduction member 16, so that the head chip 11 can be heated with less unevenness according to the temperature of the heat conduction member 16.

[0044] Further, the heat conduction member 16 has a gap portion 161 along the longitudinal direction of the head chip 11. Since the thermal conductivity of the heat conduction member 16 does not become infinitely high, some unevenness tends to remain. In particular, in the vicinity of both ends in the longitudinal direction of the head chip 11 where the holding portion 13 is fixed to the carriage 40 and the heat exchange with the carriage 40 is large, when the temperature of the carriage 40 is low, heat dissipation increases and the temperature tends to decrease. Therefore, by providing a gap without the heat conduction member 16 particularly near the center along the longitudinal direction of the head chip 11 in the gap portion 161, the heat is slightly suppressed from being transmitted to the vicinity of the center where the temperature is not likely to drop over a short distance, and the heat is made to easily flow to both ends where the temperature is likely to drop. When the temperature of the carriage 40 rises to the level of the temperature of the head chip 11, the temperature and heat flow of the heat conduction member 16 also become stable, so it is less likely that the temperature in the vicinity of the center will be significantly lowered. Thereby, in the inkjet head 10, the variation in temperature near the nozzle opening of the head chip 11 can be reduced. In particular, when the thermal conductivity of the heat conduction member 16 is lower than that of pure aluminum or the like, the temperature uniformity near the head chip 11 can be effectively compensated by this configuration.

[0045] Further, the heating amount of the heating unit 17 increases from the center to both ends in the longitudinal direction of the heat conduction member 16. As described above, particularly when the temperature of the carriage 40 is low, heat dissipation increases in the vicinity of both ends in the longitudinal direction of the head chip 11 and the temperature tends to decrease. Therefore, by using the heating unit 17 with a larger heating amount near both ends in the longitudinal direction of the head chip 11 than at the center, heating and heat dissipation can be better balanced and temperature unevenness can be reduced. Also, even in this case, the heat is quickly transmitted within the heat conduction member 16 and the heat quickly reaches the vicinity of the center where significant heat dissipation to the carriage 40 does not occur, so the temperature in the vicinity of the center is less likely to be significantly lowered.

[0046] Further, the inkjet head 10 includes a thermistor 18 that measures the temperature of the heat conduction member 16 directly or in the vicinity thereof. The thermistor 18 is positioned to perform measurement at the center in the longitudinal direction of the head chip 11. The temperatures at both ends of the head chip 11 are likely to be different depending on the positional relationship of the plurality of head chips 11 and the like, and may not represent the temperature of the entire head chip 11. Therefore, in this inkjet head 10, by measuring the temperature at one location near the center of the head chip 11, it is possible to easily adjust the temperature of the head chip 11 within a small temperature unevenness range.

[0047] Also, the head chip 11 includes individual supply channels 1111 that each send ink to a plurality of nozzles 1131, and a recovery channel that recovers ink from the middle of the individual supply channels 1111. The recovery channel has individual recovery channels 1122 that branch from the plurality of individual supply channels 1111 respectively, and a common recovery channel 1112 where the plurality of individual recovery channels 1122 merge. The common recovery channel 1112 extends along the longitudinal direction of the head chip 11. In this way, since the heated ink flows through the common recovery channel 1112 along the longitudinal direction near the nozzle opening surface, the ink transports heat, and the temperature distribution in the longitudinal direction becomes more uniform. In the inkjet head 10 having such a configuration, the temperature unevenness of the head chip 11 can be further reduced.

[0048] Also, the inkjet recording apparatus of the present embodiment has the above-described inkjet head 10. In such an inkjet recording apparatus, by reducing the above-described temperature unevenness, a more stable ink ejection can be achieved to obtain a homogeneous image.

[0049] Note that the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the above-described embodiment, the heat conduction member 16 was described as completely surrounding the head chip 11 and being in contact with the entire circumference of the head chip 11. However, it is not necessarily limited to the case of being in annular contact around the entire circumference. As long as the temperature non-uniformity of the head chip 11 can be sufficiently reduced by heat conduction, there may be a portion where the heat conduction member 16 is not in contact with the outer periphery of the bottom surface of the head chip 11. Further, in the above-described embodiment, the head chip 11 and the heat conduction member 16 were described as being in direct contact or joined via a thermally conductive bonding material. However, usually, they are joined by a bonding material that is sufficiently thin compared to a filler or the like that fills the space between the two, and if the heat conduction is not significantly hindered, the bonding material may not be thermally conductive.

[0050] Further, in the above-described embodiment, the heat conduction member 16 was described as being made of aluminum. However, generally, any material with a high thermal conductivity (for example, a higher thermal conductivity than SUS, etc.) and a higher thermal conductivity compared to the holding portion 13 (when the heat conduction member 16 is a part of the holding portion 13, the portion other than the heat conduction member 16) may be used, such as other materials, for example, silicon, carbon, aluminum nitride, etc. In addition to improving the thermal conductivity, since their coefficient of linear expansion is close to that of PZT, the durability of the head chip 11 and the bonding portion of the head chip 11 can be improved.

[0051] Also, in the above-described embodiment, the heating portion 17 is in contact with and heats the outer periphery of the heat conduction member 16, but it may also be in contact with the back surface near the outer periphery or the like.

[0052] Further, in the above-described modification 2, the case where the head chip 11 has void portions 161 on both sides in the X direction and in the above-described modification 3, the case where the head chip 11 has void portions 161a on the outer sides of both ends in the Y direction was described. However, these are not simply spaces, and a resin or ceramic material with a sufficiently low thermal conductivity compared to the heat conduction member 16 may be located inside.

[0053] In the above-described embodiment, the inkjet head 10 having a recovery channel and capable of circulating ink has been described, but the present invention is not limited thereto. Further, even when having a recovery channel, the positional relationship of this channel is not limited to that shown in the above-described embodiment. The common recovery channel 1112 may not extend in the Y direction (longitudinal direction) near the nozzle opening surface.

[0054] Also, the temperature measurement by the thermistor 18 is not necessarily limited to a single location in the center with respect to the head chip 11. It may be measured at a plurality of locations and used for operation control.

[0055] In the above-described embodiment, it has been described that the heat conductive member 16 surrounds the periphery of one head chip 11 and the heating part 17 surrounds the periphery thereof, but the present invention is not limited thereto. A plurality of head chips 11 may be collectively surrounded. In particular, when a plurality of head chips 11 are arranged side by side in the longitudinal direction, the outer periphery of a single heat conductive member 16 may be positioned so as to enclose the plurality of head chips 11, and the heating part 17 may be in contact with the heat conductive member 16 along the vicinity of the outer periphery. In addition, the specific configurations, the contents and procedures of the processing operations, etc. shown in the above-described embodiment can be appropriately changed without departing from the gist of the present invention. The scope of the present invention includes the scope of the invention described in the claims and its equivalent scope.

Explanation of Reference Numerals

[0056] 10 Inkjet head 11 Head chip 1111 Individual supply channel 1111a Inlet 1112 Common recovery channel 1121 Ink channel 1122 Individual recovery channel 1131 Nozzle 12 Manifold 121 Common supply channel 122 Common channel 123 Common discharge channel 13 Holding part 14 Inflow pipe 15 Discharge pipe 16 Heat conduction member 161, 161a Gap portion 17, 17b Heating portion 18 Thermistor 20 Filter chamber 30 Drive substrate 40 Carriage

Claims

1. A head chip having openings of a plurality of nozzles on one surface, A heat conductive member located around the one surface of the head chip and in contact with the head chip, A heating unit for heating the heat conductive member, Comprising, In a plan view of the head chip viewed from a direction perpendicular to the one surface, the heat conductive member is located at positions facing the vicinity of the center on both sides sandwiching the vicinity of the center in the longitudinal direction of the head chip in a direction perpendicular to the longitudinal direction, and has a plurality of voids arranged along the longitudinal direction of the head chip, and has no voids in a portion along the outer edge of the head chip extending in a direction perpendicular to the longitudinal direction of the head chip. An inkjet head characterized by the above.

2. The inkjet head according to claim 1, wherein the heat conductive member is in annular contact with the outer periphery of the one surface.

3. The inkjet head according to claim 2, wherein the heating unit is in annular contact with the heat conductive member outside the outer periphery of the one surface.

4. The inkjet head according to any one of claims 1 to 3, wherein the heating amount of the heating unit increases from the center to both ends in the longitudinal direction of the heat conductive member.

5. Comprising a measurement unit for measuring the temperature of the heat conductive member, The inkjet head according to any one of claims 1 to 4, wherein the measurement unit is located to perform measurement at the center in the longitudinal direction of the head chip.

6. The head chip includes an individual supply channel for sending ink to each of the plurality of nozzles and a recovery channel for recovering ink from the middle of the individual supply channel. The recovery channel has an individual recovery channel branched from each of the plurality of individual supply channels and a common recovery channel into which the plurality of individual recovery channels merge. The inkjet head according to any one of claims 1 to 5, wherein the common recovery channel extends along the longitudinal direction of the head chip.

7. An inkjet recording apparatus having the inkjet head according to any one of claims 1 to 6.

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