Liquid ejecting head and liquid ejecting apparatus

Abstract

There is provided a liquid ejecting head including: a liquid ejecting portion including a pressure chamber, an ejecting nozzle for ejecting liquid from the pressure chamber, and an energy generating element generating energy to eject the liquid from the ejecting nozzle; and a circulation flow channel including an inflow port into which the liquid flows and an outflow port from which the liquid flows, the pressure chamber being disposed between the inflow port and the outflow port. The liquid ejecting head further includes: a first thermoelectric conversion element provided on the circulation flow passage on a side closer to the inflow port than the energy generating element; and a second thermoelectric conversion element provided on the circulation flow path and adjacent to the first thermoelectric conversion element. The first thermoelectric conversion element and the second thermoelectric conversion element are driven at different timings from each other.

Description

Technical Field

[0001] This disclosure relates to a liquid jet head and a liquid jetting device. Background Technology

[0002] In the case of liquid ejection heads, such as inkjet recorders, ink (liquid) thickening is a factor contributing to image quality degradation. When an inkjet nozzle has not been used for a period of time, ink evaporates from the nozzle, thus thickening. Variations in the ejection volume and direction from each nozzle can cause streaks and uneven density in the image, leading to a decrease in image quality.

[0003] To prevent the aforementioned thickening of the ink, a mechanism for circulating the ink within a liquid jet nozzle has recently been proposed. By circulating the ink, the thickened ink near the jet nozzle is pushed aside, and fresh ink can be supplied. Japanese Patent Application Publication No. 2020-104312 discloses a configuration in which an energy generating element for jetting liquid (energy generating element for jetting) and a thermoelectric conversion element for conveying liquid within a circulating flow channel including a pressure chamber (energy generating element for circulation) are continuously arranged in the circulating flow channel.

[0004] In Japanese Patent Application Publication No. 2020-104312, the energy generating element for jetting and the energy generating element for circulation are arranged one-to-one. Due to the increased density of the jet nozzles, the flow channel width narrows, limiting the pump size. Furthermore, when the energy generating element for circulation is driven at a high frequency to increase the flow rate, and this energy generating element is a thermoelectric conversion element, reboiling occurs due to localized heating, resulting in foaming failure and a decrease in pump flow rate. This means that the frequency at which the energy generating element for circulation is driven is limited, and the flow rate is thus limited, potentially failing to resolve ink thickening at the jet nozzles. Summary of the Invention

[0005] This disclosure aims to provide a technique for improving the circulation efficiency of a liquid jet head configured to circulate liquid using an energy-generating element.

[0006] To solve the above problems, the liquid injection head disclosed herein includes:

[0007] The liquid injection section includes a pressure chamber; an injection nozzle for injecting liquid from the pressure chamber; and an energy generating element for generating energy to inject liquid from the pressure chamber from the injection nozzle.

[0008] A circulating flow channel includes: an inlet port through which liquid to be supplied to a pressure chamber flows; and an outlet port through which liquid collected from the pressure chamber flows out, wherein the pressure chamber is disposed between the inlet port and the outlet port.

[0009] A first thermoelectric conversion element is disposed on the circulating flow channel on the side closer to the inlet port than the energy generating element; and

[0010] A second thermoelectric conversion element is disposed on the circulating flow channel on the side closer to the inlet port than the energy generating element, and the second thermoelectric conversion element is disposed adjacent to the first thermoelectric conversion element.

[0011] The first thermoelectric conversion element and the second thermoelectric conversion element are driven at different timings.

[0012] The features of this disclosure will become apparent from the following description of embodiments with reference to the accompanying drawings. The following description of the embodiments is by way of example. Attached Figure Description

[0013] Figure 1 This is an oblique view of the inkjet recorder head.

[0014] Figure 2 This is a perspective view of a comparative example recording element substrate viewed from the side facing the jet nozzle.

[0015] Figure 3A This is a schematic perspective view of the U-shaped flow channel configuration in the recording element substrate of Embodiment 1 when the recording element substrate of the liquid jet head is viewed from the side facing the jet nozzle.

[0016] Figure 3B yes Figure 3A The cross-sectional view from the direction of arrow A.

[0017] Figure 3C yes Figure 3A A cross-sectional view from the direction of arrow B.

[0018] Figure 4 This is a perspective view of the recording element substrate of the modified embodiment 1, viewed from the side facing the jet nozzle.

[0019] Figure 5A It is a schematic diagram depicting the timing of the drive signal for the voltage pulse applied to the energy generating element when only the first thermoelectric conversion element of the comparative example is driven.

[0020] Figure 5B It describes something at a higher level Figure 5AA schematic diagram of the timing of the drive signal for the voltage pulse applied to the energy generating element when the drive frequency only drives the first thermoelectric conversion element of the comparative example.

[0021] Figure 5C It is a schematic diagram depicting the drive signals applied to the first thermoelectric conversion element and the second thermoelectric conversion element of Embodiment 1.

[0022] Figure 6A This is a perspective view of a portion of the flow channel near the jet nozzle of the recording element substrate of Embodiment 2, viewed from the side facing the jet nozzle.

[0023] Figure 6B This is a schematic diagram of the drive signal that indicates the timing of the voltage pulses applied to the three thermoelectric conversion elements.

[0024] Figure 7A This is a perspective view of the arrangement from the perforated plate to the first flow channel member when viewing the recording element substrate of Embodiment 3 from the side facing the jet nozzle.

[0025] Figure 7B This is a perspective view of the arrangement of the recording element substrate of Embodiment 3 from the first substrate to the second substrate when viewed from the side facing the jet nozzle.

[0026] Figure 7C It's from the direction of arrow D. Figure 7A and Figure 7B Cross-sectional view.

[0027] Figure 8A This is a perspective view of the recording element substrate of Embodiment 4, viewed from the side facing the jet nozzle.

[0028] Figure 8B It is viewed from the direction of arrow C. Figure 8A Cross-sectional view.

[0029] Figure 8C This is a cross-sectional view showing the formation of a supply-side common flow channel and a discharge-side common flow channel, which pass through a second flow channel member stacked on a first substrate.

[0030] Figure 9 This is a diagram used to describe the recording element substrate of Embodiment 5.

[0031] Figure 10 This is a diagram used to describe the drive signals of the thermoelectric conversion element in Embodiment 6.

[0032] Figure 11 It is a block diagram depicting the control configuration of a liquid injection device. Detailed Implementation

[0033] Embodiments of this disclosure will be described in detail with reference to the accompanying drawings and examples. The dimensions, materials, shapes, relative positions, etc., of the components described in the embodiments may be appropriately varied depending on the configuration of the device to which this disclosure is applied or various conditions. In other words, the following embodiments are not intended to limit the scope of this disclosure.

[0034] In the following embodiments, multiple features are described, but not all of these features are necessary for implementing this disclosure, and the features can be freely combined. Furthermore, in the accompanying drawings, identical or similar components in the embodiments are represented by the same reference numerals, and redundant descriptions thereof are omitted.

[0035] Example 1

[0036] Description of header configuration

[0037] Figure 1 This is a perspective view of an inkjet recording head 100 (hereinafter also referred to as a "recording head"), which can be used as a liquid ejection head of this disclosure. The recording head 100 according to Embodiment 1 of this disclosure serves as a liquid ejection device installed in a recording device based on an inkjet recording system. For example, the recording device allows the recording head 100 to selectively eject liquids of multiple colors and allows the liquid to deposit on a recording medium, thereby forming (recording) characters, symbols, images, etc. Any medium can be used for the recording medium, as long as it allows the formation of an image by depositing droplets. For example, recording media of various materials and formats can be used, such as paper, cloth, optical disc label surfaces, plastic sheets, OHP sheets, and envelopes. A typical example of a liquid ejected by a liquid ejection head applicable to this disclosure is ink, but the liquid is not limited to ink and can be a reaction solution or pretreatment solution added to the liquid ejection device. In the recording head 100, a plurality of recording element substrates 4 are arranged along the Y direction, in which a plurality of recording elements are arranged along the Y direction. This shows a full-line recording head 100, in which recording element substrates 4 are arranged in the Y direction at a distance corresponding to the width of an A4 dimension.

[0038] Each recording element substrate 4 is connected to the same electrical wiring board 102 via a flexible wiring board 101. The electrical wiring board 102 is provided with a power supply terminal 103 for receiving power and a terminal for receiving power from the CPU 800 (see [link to CPU 800], which is a control unit). Figure 11 The signal input terminal 104 sends the ejection signal. In the ink supply unit 105, a circulating flow channel is formed to supply ink received from the ink tank (not shown) to each recording element substrate 4, or to collect ink that is not consumed during the recording process.

[0039] In the above configuration, each recording element disposed on the recording element substrate 4 uses power supplied from the power supply terminal 103 based on the ejection signal input through the input terminal 104. Figure 1 Ink is ejected in the Z direction (supply by ink supply unit 105).

[0040] Figure 11 This is a block diagram depicting the control system of a recording device 1000 using the recording head 100 of Embodiment 1. The CPU 800 is a control unit that controls each unit of the recording device 1000 based on a program (e.g., a processing procedure) stored in the ROM 301. RAM 302 serves as a working area, etc., when the CPU 800 performs processing. The CPU 800 receives image data from a host device 400 external to the recording device 1000 and controls the driving of elements disposed in the recording head 100 by controlling the head driver 100A based on this image data. The CPU 800 receives temperature information detected by the temperature sensor 500. The CPU 800 uses the head driver 100A to control the driving of various energy-generating elements (thermoelectric conversion elements) of the recording head 100.

[0041] The CPU 800 also controls the drivers of various actuators installed in the recording device 1000. For example, the CPU 800 controls the motor driver 303A of the carriage motor 303 to move the carriage that holds the recording head 100. The CPU 800 also controls the motor driver 304A of the transport motor 304 to transport the recording medium, and controls the pump driver 210A of the external pump 210. Figure 11 The instructions specify the processing to be performed when image data is received from the host device 400, but the processing can also be performed on the recording device 1000 without relying on data from the host device 400.

[0042] Description of recording elements

[0043] Figures 3A to 3C It's enlarged. Figure 1 The diagram shows a portion of the recording element substrate 4 of the recording head 100, and indicates a portion of the flow channel near the jet nozzle according to Embodiment 1. Figure 3A This is a schematic perspective view of the U-shaped flow channel configuration when viewing the recording element substrate 4 of the liquid jet head from the side facing the jet nozzle (along the -Z direction). Figure 3B yes Figure 3A The cross-sectional view from the direction of arrow A. Figure 3C yes Figure 3A A cross-sectional view from the direction of arrow B.

[0044] First, the layout configuration of each unit of the recording head 100 according to Embodiment 1 will be described. Here, in Embodiment 1, in order to specify the layout of each unit of the recording head 100, the first direction, the second direction, and the third direction are assumed to be the Z direction, the X direction, and the Y direction, respectively, and these three directions are orthogonal to each other, but the configuration of the present invention is not limited to this. For example, without affecting the function of the recording head 100, these three directions may intersect each other and be slightly inclined from the Z direction, the X direction, and the Y direction, respectively.

[0045] As part of the configuration forming the ink ejection section 40 (liquid ejection section), the recording element substrate 4 constituting the recording head 100 according to Embodiment 1 includes a pressure chamber 3, an ejection nozzle 2, and an energy generating element 1. This energy generating element generates energy to eject ink from the pressure chamber through the ejection nozzle 2. In Embodiment 1, the energy generating element 1 is configured as a thermoelectric conversion element. The energy generating element 1 is not limited to a thermoelectric conversion element, but may be a piezoelectric element, etc. The ink ejection section 40 is disposed on a circulating flow channel 7. The circulating flow channel 7 includes an inlet port 8 (supply flow channel) through which ink to be supplied to the ink ejection section 40 flows in; and an outlet port 9 (discharge flow channel) through which ink collected from the ink ejection section 40 flows out. The ink ejection section 40 is disposed on the circulating flow channel 7 between the inlet port 8 and the outlet port 9.

[0046] The recording element substrate 4 also includes a first thermoelectric conversion element 5 and a second thermoelectric conversion element 6, serving as energy generating elements to generate energy for ink to flow within the circulating flow channel. The first thermoelectric conversion element 5 is disposed on the side of the circulating flow channel 7 closer to the inflow port 8 than the energy generating element 1, and the second thermoelectric conversion element 6 is disposed on the side of the circulating flow channel 7 closer to the inflow port 8 than the energy generating element 1, at a position adjacent to the first thermoelectric conversion element 5. In Embodiment 1, the second thermoelectric conversion element 6 is disposed on the side of the circulating flow channel 7 further away from the inflow port 8 than the first thermoelectric conversion element 5.

[0047] like Figure 3AAs shown, the circulating flow channel 7 is an approximately U-shaped flow channel. The inlet port 8 and the outlet port 9 are positioned on one side of the ink jetting section 40 in the X direction (second direction) (i.e., the direction of the nozzle 2 opening (ink jetting position)) intersecting the Z direction (first direction). Furthermore, the inlet port 8 and the outlet port 9 are arranged in a row in the Y direction (third direction) intersecting both the Z direction (first direction) and the X direction (second direction). The circulating flow channel 7 includes: an upstream flow channel 71 extending from the inlet port 8 (extending from one side to the other along the X direction); and a downstream flow channel 72 extending from the upstream flow channel 71 by turning in the opposite direction (extending from the other side to one side along the X direction). A first thermoelectric conversion element 5 and a second thermoelectric conversion element 6 are disposed on the upstream flow channel 71, and the ink jetting section 40 is disposed on the downstream flow channel 72.

[0048] like Figure 3B As shown, the recording element substrate 4 of Embodiment 1 is configured such that a first substrate 17, a first flow channel member 13 (first flow channel forming member), and an orifice plate 16 are sequentially stacked along the Z direction. On the surface of the first substrate 17 in the cross-sectional view from the direction of arrow A, an energy generating element 1 (thermoelectric conversion element) is provided, and a jet nozzle 2 is formed at a position on the orifice plate 16 corresponding to the energy generating element 1.

[0049] like Figure 3C As shown, on the surface of the first substrate 17 in a cross-sectional view from the direction of arrow B, a first thermoelectric conversion element 5 and a second thermoelectric conversion element 6 (thermoelectric conversion elements) are disposed adjacent to each other. The orifice plate 16 and the first substrate 17 form a separate pressure chamber 3 for each set of jet nozzles 2 and energy generating elements 1. The pressure chamber 3 includes partition walls between the jet nozzles 2 and energy generating elements 1 disposed at multiple locations in the Y direction. The energy generating elements 1 are heated based on an input drive signal, thereby generating film boiling in the ink. The ink is ejected from the jet nozzles 2 by the growth energy of the generated bubbles.

[0050] The partition wall forming the pressure chamber 3 also constitutes part of the circulating flow channel 7, which includes a first thermoelectric conversion element 5 and a second thermoelectric conversion element 6 arranged in the Y direction. The first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 may have the same or different dimensions. In this U-shaped flow channel configuration, the thermoelectric conversion elements and energy generating elements are alternately arranged along the direction of the jet nozzle array (Y direction).

[0051] The structure of the recording element substrate 4 of Embodiment 1 will be described in detail.

[0052] like Figure 3AAs shown, the recording element substrate 4 includes a common flow channel 12 communicating with an inlet port 8 and an outlet port 9, respectively. Ink jet sections 40 are disposed at multiple locations aligned along the Y direction (third direction), and the common flow channel 12 is a common flow channel for the multiple ink jet sections 40. Multiple circulating flow channels 7, corresponding to the multiple ink jet sections 40, extend along the X direction (second direction) between the multiple ink jet sections 40, such that the upstream flow channel 71 intersects with the rows of the multiple ink jet sections 40. The common flow channel 12 is configured to extend along the Y direction at a location on one side of the inlet port 8 and outlet port 9 in the X direction, and communicate with the multiple inlet ports 8 and multiple outlet ports 9, respectively, corresponding to the multiple ink jet sections 40. Multiple energy generating elements 1 and multiple first thermoelectric conversion elements 5, respectively disposed for the multiple ink jet sections 40, are alternately arranged in a manner aligned along the Y direction (third direction).

[0053] like Figure 3B and Figure 3C As shown, the first substrate 17 has a first surface 171 on which the ink jetting portion 40, the circulating flow channel 7, and the thermoelectric conversion elements 5 and 6 are disposed. A first flow channel member 13 is a flow channel forming member stacked on the first surface 171 of the first substrate 17 and includes a partition wall 130 forming part of the circulating flow channel 7. An orifice plate 16 (with the jet nozzle 2 opening in it) is stacked on the first flow channel member 13 on the opposite side of the first substrate 17. The pressure chamber 3 and the circulating flow channel 7 are defined by the first surface 171, the partition wall 130, and the orifice plate 16 of the first substrate 17. The first substrate 17 includes a through-hole 173 that penetrates between the first surface 171 and the second surface 172 (which is the rear surface of the first substrate 171) of the first substrate 17 along the Z direction (first direction) on one side of the inlet port 8 and the outlet port 9 in the X direction (second direction). A common flow channel 12 is defined by the through-hole 173, the flow channel member 13, and the orifice plate 16.

[0054] like Figure 3AAs shown, the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 are arranged adjacent to each other in the X direction (second direction) at different positions from the energy generating element 1 in the Y direction (third direction). The partition wall 130 of the first flow channel member 13 includes a first partition wall portion 131 extending in the X direction to define a plurality of circulating flow channels 7 corresponding to the plurality of ink jet portions 40 in the Y direction. In each circulating flow channel 7, the partition wall 130 also includes a second partition wall portion 132 extending in the X direction to define the energy generating element 1, the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 in the Y direction. The side surface of the second partition wall portion 132 on one side in the Y direction forms part of the upstream flow channel 71, and the side surface of the second partition wall portion 132 on the other side in the Y direction forms part of the downstream flow channel 72 and the pressure chamber 3.

[0055] Next, the circulating flow channel 7 in Embodiment 1 will be described, wherein the ink... Figure 3A As shown, the energy is supplied from the inlet port 8 to the pressure chamber 3 and discharged through the outlet port 9 to the common flow channel 12. As a mechanism for generating flow within the circulating flow channel 7, the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 are disposed between the inlet port 8 and the energy generating element 1.

[0056] The principle of the circulation method using the thermoelectric conversion element according to Embodiment 1 will be described. When the ink is overheated by the thermoelectric conversion element, bubbles are generated due to the boiling of the ink film. Here, in the circulation flow channel 7, thermoelectric conversion elements 5 and 6 are positioned closer to the inflow port 8 than to the outlet port 9 side, and the first flow resistance R1 between thermoelectric conversion elements 5 and 6 and the inflow port 8 becomes less than the second flow resistance R2 between thermoelectric conversion elements 5 and 6 and the outlet port 9. Therefore, the bubbles generated by the boiling of the ink film will further grow towards the supply flow channel side where the flow resistance is lower. Then, during the bubble shrinkage phase, ink flows in to compensate for the shrinkage capacity, so the flow of ink from the supply flow channel side where the bubbles have greatly grown becomes faster than the flow from the outlet flow channel side. Therefore, as Figure 3A As shown, flow is generated from the supply flow channel side to the discharge flow channel side, thereby circulating the ink.

[0057] In the above configuration, when the ink in pressure chamber 3 is consumed due to the jetting operation, fresh, unthickened ink is supplied to the jetting nozzle 2. Even when no jetting operation is performed, the ink continues to circulate in the circulation flow channel 7, and fresh ink is supplied to the jetting nozzle 2. Here, a filter 14 can be installed to prevent foreign objects, bubbles, etc., from entering the flow channel and the jetting nozzle 2. If the filter 14 is provided not only at the inlet portion of the inflow port 8 through which the ink flows into the circulation flow channel 7, but also at the outlet port 9, then when ink is supplied through the outlet port 9 (exiting the flow channel) during the jetting operation, the entry of foreign objects can be prevented.

[0058] The amount of circulating flow is affected by the ratio of flow resistances R1 and R2, as well as the size of the bubble. When the energy generating element used to generate the circulating flow is a thermoelectric conversion element, as in Example 1, the flow resistance ratio R1 / R2 can be set in the range of 0.05 to 0.4. By setting the flow resistance ratio R1 / R2 within this range, the circulating flow within the circulating flow channel 7 can be increased. In Example 1, thermoelectric conversion elements 5 and 6 are arranged adjacent to each other in the cross-sectional view from the direction of arrow B, but the invention is not limited to this; any arrangement is acceptable as long as the aforementioned resistive relationship can be established with the thermoelectric conversion elements 5 and 6.

[0059] The adjustment of the flow resistance ratio R1 / R2 is not limited to a specific method, but can also be performed by changing the positions of thermoelectric conversion elements 5 and 6 on the circulating flow channel 7. In other words, the magnitudes of the flow resistances R1 and R2 are changed by altering the flow channel distances between thermoelectric conversion elements 5 and 6 and the inlet port 8, and between thermoelectric conversion elements 5 and 6 and the outlet port 9. Another method is to change the cross-section of the flow channels on both sides of thermoelectric conversion elements 5 and 6, or both the flow channel distance and the cross-section of the flow channels can be changed. To change the cross-section of the flow channels, for example, a structure for interrupting the flow can be provided on the flow channels, thereby changing the flow resistances R1 and R2.

[0060] Description of drive signals

[0061] The circulating flow diminishes over time and stops after a predetermined period. Therefore, to continuously generate the circulating flow, the thermoelectric conversion element used to generate the circulating flow needs to be driven repeatedly. The driving cycle of the thermoelectric conversion element used to generate the circulating flow is not particularly limited, as long as the thickened ink in the jet nozzle 2 can be discharged.

[0062] Generally, as the driving frequency of the thermoelectric conversion element used to generate the circulating flow increases and the foaming cycle becomes shorter, the effect of expelling thickened ink increases. However, if the frequency is too high, problems such as reboiling may occur; that is, there is a limitation to increasing the driving frequency. Therefore, in Embodiment 1, two thermoelectric conversion elements (first thermoelectric conversion element 5 and second thermoelectric conversion element 6) are provided for generating the circulating flow, and the two thermoelectric conversion elements are driven at different timings, thereby improving the circulation efficiency by interpolating the drives. In Embodiment 1, as the main element, the first thermoelectric conversion element 5 is located at the most effective position where the flow resistance ratio R1 / R2 is in the range of 0.05 to 0.4, and as the secondary element, the second thermoelectric conversion element 6 is arranged adjacent to the first thermoelectric conversion element 5, such as... Figure 3A As shown.

[0063] The second thermoelectric conversion element 6 can be disposed on the supply flow channel side, as shown in the figure. Figure 4 The modified example shown is the case of the recording element substrate 4b.

[0064] Since the same voltage pulse can be input, the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 can be the same size. Even if the thermoelectric conversion elements have different sizes in order to suppress the total power consumed by the multiple thermoelectric conversion elements, the thermoelectric conversion elements can be set to have the same width in the flow channel width direction.

[0065] Figure 5C Indicates the timing of the drive signal. Figure 5C The drive signals for the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 are indicated, and the injection pulses are paused in advance before driving thermoelectric conversion elements 5 and 6. Furthermore, as mentioned above, the first thermoelectric conversion element 5 is positioned at the optimal location where the flow rate is highest. If the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 are driven at the same timing in this arrangement, the foaming generated by the second thermoelectric conversion element 6 will change the flow resistance ratio before and after the first thermoelectric conversion element 5, potentially leading to flow rate degradation. To prevent this, the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 are driven alternately at different timings. The drive frequencies of the voltage pulses applied to the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 can be the same or different.

[0066] Effect

[0067] For comparison with Example 1, reference will be used. Figure 2 as well as Figures 5A to 5C Describe the configuration of the comparison example. Figure 2This is a perspective view of a U-shaped flow channel configuration of a comparative example recording element substrate 4x from the side facing the jet nozzle 2 (-Z direction), wherein a thermoelectric conversion element 5 is provided for a jet nozzle 2. Figure 5A The timing of the drive signal that indicates the voltage pulse applied to the energy generating element 1 according to the comparative example. Figure 5A In the diagram, time t is plotted on the horizontal axis, and the driving timing f of the voltage pulse indicates the driving frequency expressed as the reciprocal of time t (that is, the same applies to the following description). The description will show the thermoelectric conversion element 5 positioned at the optimal location where the flow rate becomes highest and driven at an appropriate frequency so that foaming is not affected by localized heating (e.g., Figure 5A The case where f1 = 15kHz, f2 = 15kHz is used for driving.

[0068] and Figure 5C Compared to the case of alternating driving of the two thermoelectric conversion elements 5 and 6 (such as in Example 1), in which only the first thermoelectric conversion element 5 is driven at the optimal position with a higher flow rate... Figure 5A In this case, the flow rate can be higher. This is because, in Embodiment 1, the flow rate of the second thermoelectric conversion element 6 (sub-element) is slightly lower than that of the first thermoelectric conversion element 5.

[0069] On the other hand, if even higher flow rates are required, if only the driving frequency f1 of the first thermoelectric conversion element 5 is maintained at, for example, 30kHz, such as Figure 5B As shown, the localized heating at the thermoelectric conversion element will increase. This can lead to bubbling failure, resulting in a decrease in pump flow rate.

[0070] Compared to this comparative example, Figure 5C The driving timing of the voltage pulses applied to the thermoelectric conversion elements 5 and 6 in Embodiment 1 is indicated. For example, the driving frequency f1 of the first thermoelectric conversion element 5 is set to 15 kHz, and the driving frequency f2 of the second thermoelectric conversion element 6 is set to 15 kHz, and the driving is performed by offsetting the first thermoelectric conversion element 5 by half a cycle. In this case, the frequency F1 between the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 becomes 30 kHz. Therefore, by driving the two thermoelectric conversion elements separately, the ink temperature rise caused by local heating when driving one thermoelectric conversion element at a high frequency can be suppressed. Furthermore, by alternately and repeatedly driving the two thermoelectric conversion elements at staggered timings, the flow rate can be increased, and fresh ink can be supplied to the nozzle section, which can suppress the thickening of ink at the nozzle section.

[0071] Example 2

[0072] Reference Figure 6A and Figure 6BThe cyclic configuration of the recording element substrate 4c according to Embodiment 2 of this disclosure is described, with a focus on aspects that differ from the recording element substrate 4 of Embodiment 1.

[0073] The matters not specifically described herein in Example 2 are the same as those in Example 1.

[0074] Description of recording elements

[0075] Figure 6A This is a perspective view of a portion of the flow channel near the jet nozzle of the recording element substrate 4c according to Embodiment 2, viewed from the side facing the jet nozzle (-Z direction). In Embodiment 1, the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 are arranged adjacent to each other, but in the configuration of Embodiment 2, the first thermoelectric conversion element 5, the second thermoelectric conversion element 6 and the third thermoelectric conversion element 10 are arranged in a row.

[0076] In Example 2, just as in Example 1, such as Figure 6A As shown, the first thermoelectric conversion element 5 is configured as the main element, and the second thermoelectric conversion element 6 and the third thermoelectric conversion element 10 are configured as auxiliary elements. In embodiment 2, the first thermoelectric conversion element 5 is disposed in the center, and the second thermoelectric conversion element 6 and the third thermoelectric conversion element 10 are arranged adjacent to it on each side, as shown. Figure 6A As shown. Specifically, the third thermoelectric conversion element 10 is positioned on the side of the specific energy generating element 1 closer to the inflow port 8 in the circulating flow channel 7, that is, on the opposite side of the second thermoelectric conversion element 6, adjacent to the first thermoelectric conversion element 5. In other words, the third thermoelectric conversion element 10 is positioned on the circulating flow channel 7 at a location closer to the inflow port 8 than the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 (the closest of the three thermoelectric conversion elements to the inflow port 8). The positional order of the first thermoelectric conversion element 5, the second thermoelectric conversion element 6, and the third thermoelectric conversion element 10 is not limited to this, as long as the order in which the resistance relationship between the thermoelectric conversion elements is established is acceptable.

[0077] Description of drive signals

[0078] Figure 6B The timing of the voltage pulses applied to the three thermoelectric conversion elements 5, 6, and 10 is indicated. In Embodiment 2, the first to third thermoelectric conversion elements 5, 6, and 10 are driven at different timings than each other, and as in Embodiment 1, the three thermoelectric conversion elements 5, 6, and 10 are repeatedly driven to continuously generate cyclic flow. For example, the three thermoelectric conversion elements 5, 6, and 10 are repeatedly driven in this order.

[0079] Effect

[0080] like Figure 6BAs shown, the driving frequencies f1, f2, and f3 of the first, second, and third thermoelectric conversion elements 5, 6, and 10 are each set to, for example, 10 kHz, and the first thermoelectric conversion element 5, the second thermoelectric conversion element 6, and the third thermoelectric conversion element 10 are driven sequentially with a 1 / 3 cycle stagger. In this case, the frequency F1 between the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6, and the frequency F2 between the second thermoelectric conversion element 6 and the third thermoelectric conversion element 10, become F1 = F2 = 30 kHz. Therefore, compared to the case of alternately driving the two thermoelectric conversion elements 5 and 6 (as in Embodiment 1), the flow rate can be further increased, and localized heating can be suppressed due to the drive separation. According to this configuration, the number of thermoelectric conversion elements that can be set is limited by the size of the thermoelectric conversion elements, the length of the circulating flow channel, the distance between the rows of injection nozzles, etc., but the circulation efficiency in the circulating flow channel can be improved.

[0081] (Example 3) Three-dimensional flow channel configuration

[0082] Reference Figures 7A to 7C The cyclic configuration of the recording element substrate 4d according to Embodiment 3 of this disclosure is described, with a focus on aspects that differ from the recording element substrates of Embodiments 1 and 2. Matters not specifically described herein in Embodiment 3 are the same as those in the above embodiments.

[0083] Description of recording elements

[0084] Figures 7A to 7C This is a diagram depicting the flow channel configuration and wiring near the jet nozzle of the recording element substrate 4d according to Embodiment 3. Figure 7A and Figure 7B This is a 4D perspective view of the recording element substrate viewed from the side facing the jet nozzle (-Z direction), and Figure 7C It is viewed from the direction of arrow D. Figure 7A and Figure 7B Cross-sectional view. Figure 7A Indicates the configuration from the orifice plate 16 to the first flow channel member 13, and Figure 7B Indicates the arrangement from the first substrate 17 to the second substrate 18.

[0085] like Figure 7CAs shown, the recording element substrate 4d of Embodiment 3 has the following configuration, wherein a second substrate 18, a second flow channel member 15 (a second flow channel forming member), a first substrate 17, a first flow channel member 13, and an orifice plate 16 are stacked sequentially along the Z direction. An energy generating element 1 (thermoelectric conversion element) is disposed on the surface (first surface 171) of the first substrate 17, and a jet nozzle 2 is formed at a position on the orifice plate 16 corresponding to the energy generating element 1. Between the orifice plate 16 and the first substrate 17, a separate pressure chamber 3 is formed for each jet nozzle 2 and energy generating element 1 via the first flow channel member 13. The pressure chamber 3 has partition walls between the jet nozzle 2 and the energy generating element 1 at multiple positions disposed in the Y direction.

[0086] The structure of the recording element substrate 4d in Embodiment 3 will be described in detail.

[0087] like Figure 7C As shown, when viewed along the Y direction (third direction), the circulating flow channel 7d of the recording element substrate 4d is approximately U-shaped. The inlet port 8 and outlet port 9 are arranged in a row along the Z direction (first direction), which is the direction of the opening of the jet nozzle 2 (ink jetting direction), and both are located on one side of the X direction (second direction) relative to the ink jetting portion 40. The circulating flow channel 7d includes: an upstream flow channel 71d extending along the X direction from one side of the inlet port 8 to the other; and a downstream flow channel 72d extending along the X direction from one side to the other by reversing its direction to the opposite direction to the upstream flow channel 71d. Thermoelectric conversion elements 5 and 6 are disposed on the upstream flow channel 71d, and the ink jetting portion 40 is disposed on the downstream flow channel 72d. In other words, the ink jetting portion 40 and the thermoelectric conversion elements 5 and 6 are disposed at different positions along the Z direction.

[0088] like Figure 7A and Figure 7B As shown, the ink ejection section 40 is positioned at multiple locations aligned along the Y direction. The upstream flow channel 71d and the downstream flow channel 72d extend along the X direction and are also arranged in a row along the Z direction, as shown... Figure 7C As shown. The common flow channel 12 extends along the Y direction on one side of the inflow port 8 and the outflow port 9 in the X direction, and is connected to the plurality of inflow ports 8 and the plurality of outflow ports 9 respectively provided corresponding to the plurality of ink jet sections 40.

[0089] like Figures 7A to 7C As shown, multiple circulating flow channels 7d (upstream flow channel 71d, downstream flow channel 72d) corresponding to multiple ink jet sections 40 are aligned along the Y direction. Figure 7AAs shown, the multiple energy generating elements 1, corresponding to the multiple ink ejection sections 40, are also aligned along a third direction. Figure 7B As shown, the multiple first thermoelectric conversion elements 5 and multiple second thermoelectric conversion elements 6, which are arranged corresponding to the multiple ink ejection sections 40, are aligned along the Y direction.

[0090] like Figure 7C As shown, the first substrate 17 has: a first surface 171 on which an ink ejection portion 40 is disposed and forms part of the downstream flow channel 72d and the pressure chamber 3; and a second surface 172 located on the rear surface of the first surface 171 and forming part of the upstream flow channel 71d. The first substrate 17 also includes a connecting hole 174 forming a through flow channel 11 (connecting flow channels), the connecting hole passing through between the first surface 171 and the second surface 172 along the Z direction and connecting the upstream flow channel 71d and the downstream flow channel 72d on the circulating flow channel 7d.

[0091] A first flow channel member 13 is stacked on the first surface 171 of the first substrate 17 and forms part of the downstream flow channel 72d and the pressure chamber 3. An orifice plate 16 (with the injection nozzle 2 opening in it) is stacked on the opposite side of the first substrate 17 on the first flow channel member 13 and forms part of the downstream flow channel 72d and the pressure chamber 3. A second flow channel member 15 is stacked on the second surface 172 of the first substrate 17 and forms part of the upstream flow channel 71d. A second substrate 18 is stacked on the opposite side of the first substrate 17 on the second flow channel member 15. A first thermoelectric conversion element 5 and a second thermoelectric conversion element 6 are disposed on the side of the second substrate 18 facing the second flow channel member 15 and form part of the upstream flow channel 71d.

[0092] On one side of the inflow port 8 and the outflow port 9 along the X direction, a common flow channel 12 is formed by a common hole that sequentially passes through the first flow channel member 13, the first substrate 17, the second flow channel member 15, and the second substrate 18 in the Z direction.

[0093] The circulating flow channel 7d according to Embodiment 3 will now be described, which supplies ink to the pressure chamber 3 and discharges the ink to the common flow channel 12. Figure 7CAs shown, the second substrate 18, the second flow channel member 15, the first substrate 17, the first flow channel member 13, and the perforated plate 16 each form a wall, and each recording element substrate 4d constitutes a separate circulating flow channel 7d. The circulating flow channel 7d is composed of an upstream flow channel 71d, a through flow channel 11, and a downstream flow channel 72d. The upstream flow channel 71d is formed between the first substrate 17 and the second substrate 18 by the second flow channel member 15. The through flow channel 11 is formed by the connection hole 174 of the first substrate 17. The downstream flow channel 72d is formed between the first substrate 17 and the perforated plate 16 by the first flow channel member 13. Ink flowing into the circulating flow channel 7d from the common flow channel 12 via the inlet port 8 is supplied to the pressure chamber 3 via the upstream flow channel 71d and the through flow channel 11. Ink collected from the pressure chamber 3 but not ejected is discharged from the outlet port 9 to the common flow channel 12 via the downstream flow channel 72d.

[0094] As a mechanism for generating flow within the circulating flow channel 7d, the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 are disposed in the middle portion of the circulating flow channel 7d. The thermoelectric conversion elements 5 and 6 are disposed on the surface of the second substrate 18 at a position facing the second surface 172, which is the opposite side surface (rear surface) of the surface on which the energy generating element 1 of the first substrate 17 is disposed.

[0095] In Embodiment 3, the first thermoelectric conversion element 5, as the main element, is disposed at the most effective position, where the flow resistance ratio R1 / R2 is in the range of 0.05 to 0.4. The second thermoelectric conversion element 6, as a secondary element, is disposed on the second substrate 18, identical to the first thermoelectric conversion element 5. The positions of the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 are not limited to the above-described configuration; rather, as long as a predetermined resistance relationship is established between the thermoelectric conversion elements 5 and 6 in the circulating flow channel 7d, the thermoelectric conversion elements 5 and 6 can also be disposed on the first substrate 17. Furthermore, in Embodiment 3, two thermoelectric conversion elements are disposed in the circulating flow channel, but three or more thermoelectric conversion elements can also be disposed as in Embodiment 2.

[0096] The flow direction of the circulating flow channel 7d is from Figure 7C The arrow in the diagram indicates that if the ink jet direction at the jet nozzle 2 is from bottom to top, then the flow direction of the circulating flow channel 7d in the through flow channel 11 is from bottom to top, and the ink supplied from the through flow channel 11 to the pressure chamber 3 flows into the common flow channel 12 through the outlet port 9.

[0097] In this configuration, if the ink in pressure chamber 3 is consumed due to the jetting operation, fresh, unthickened ink is supplied to the jetting nozzle 2. Even when no jetting operation is performed, the ink circulates in the circulation channel, and fresh ink is supplied to the jetting nozzle 2.

[0098] Effect

[0099] In the configuration of Embodiment 3 described above, thermoelectric conversion elements 5 and 6 are positioned below the energy generating element 1 when ink is ejected from the nozzle in an upward direction. Furthermore, thermoelectric conversion elements 5 and 6 are positioned on the surface of the second substrate 18 at a location on the rear surface (second surface 172) of the surface on which the energy generating element 1 is located, facing the first substrate 17. In the case of a two-dimensional U-shaped flow channel configuration along the X and Y directions, as described in Embodiments 1 and 2, the inlet port 8 and outlet port 9 are positioned close to each other, which can cause the ink to thicken due to recycling. However, in Embodiment 3, this configuration is three-dimensional in the Z direction, thus increasing the distance between the inlet port 8 and the outlet port 9, and by increasing the driving frequency of the thermoelectric conversion elements 5 and 6, the thickening of the ink due to recycling can be suppressed, thereby increasing the flow rate.

[0100] Furthermore, according to this configuration, the resolution of the recording element substrate 4d is less affected by the resolution of the thermoelectric conversion elements 5 and 6, thus improving the resolution of the recording element substrate 4d. Additionally, by making the circulating flow channel 7d independent, the flow rate can be increased, and the energy efficiency for circulation in the thermoelectric conversion elements 5 and 6 can be improved.

[0101] Example 4

[0102] Reference Figures 8A to 8C The cyclic configuration of the recording element substrate 4e according to Embodiment 4 of this disclosure is described, with a focus on aspects that differ from the recording element substrates of Embodiments 1 to 3.

[0103] Matters not specifically described in Example 4 are the same as those in the above examples.

[0104] Figures 8A to 8C This is a diagram depicting a portion of the flow channel near the jet nozzle of the recording element substrate 4e according to Embodiment 4. Figure 8A This is a perspective view of the recording element substrate 4e as seen from the side facing the jet nozzle (-Z direction). Figure 8B and Figure 8C It is viewed from the direction of arrow C. Figure 8A Cross-sectional view of.

[0105] An energy generating element 1 (thermoelectric conversion element) is disposed on the surface (first surface 171) of the first substrate 17, and a jet nozzle 2 is formed at a position on the perforated plate 16 corresponding to the energy generating element 1. Furthermore, on the surface of the first substrate 17, in a direction perpendicular to the array of jet nozzles in the Y direction, a first thermoelectric conversion element 5 and a second thermoelectric conversion element 6 are disposed adjacent to the energy generating element 1. A pressure chamber 3 includes a partition wall between the plurality of jet nozzles 2 disposed in the Y direction and the energy generating element 1. The partition wall constituting the pressure chamber 3 extends in a direction perpendicular to the Y direction (i.e., the array direction of the plurality of jet nozzles 2) and forms a circulating flow channel 7e containing the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6. A supply-side through-flow channel 21 communicating with the inlet port 8 is formed through the first substrate 17. Similarly, a discharge-side through-flow channel 22 communicating with the outlet port 9 is formed through the first substrate 17.

[0106] The structure of the recording element substrate 4e of Embodiment 4 will be described in detail.

[0107] like Figure 8A As shown, in embodiment 4, the circulating flow channel 7e extends approximately linearly along the X direction (second direction). The inlet port 8 is located on one side of the pressure chamber 3 in the X direction, and the outlet port 9 is located on the other side of the pressure chamber 3 in the X direction. In other words, the circulating flow channel 7e is a flow channel extending along the X direction, such that the inlet port 8, pressure chamber 3, and outlet port 9 are arranged in a row in this order in the X direction. Thermoelectric conversion elements 5 and 6 are disposed on the circulating flow channel 7e on the side closer to the inlet port 8 than the energy generating element 1.

[0108] like Figure 8A As shown, ink jet sections 40 are disposed at multiple locations aligned along the Y direction (third direction), and circulating flow channels 7e are also disposed at multiple locations aligned along the Y direction. Multiple energy generating elements 1 corresponding to the multiple ink jet sections 40 are also aligned along the Y direction, and multiple first thermoelectric conversion elements 5 and multiple second thermoelectric conversion elements 6 are also aligned along the Y direction. Multiple inflow ports 8 corresponding to the multiple circulating flow channels 7e are also aligned along the Y direction, and multiple outflow ports 9 are also aligned along the Y direction.

[0109] like Figure 8BAs shown, multiple inflow ports 8 and multiple outflow ports 9 are configured to communicate with each other via a supply-side through-flow channel 21, an outflow-side through-flow channel 22, and a common flow channel 12. The supply-side through-flow channel 21 is formed by a through-hole on one side (outer side of the inflow port 8) of the first substrate 17 in the X direction, so as to pass through between the first surface 171 and the second surface 172 in the Z direction. The outflow-side through-flow channel 22 is formed by a through-hole on the other side (outer side of the outflow port 9) of the first substrate 17 in the X direction, so as to pass through between the first surface 171 and the second surface 172 in the Z direction. The common flow channel 12 is formed on one side of the second surface 172 of the first substrate 17, so as to communicate with the supply-side through-flow channel 21 and the outflow-side through-flow channel 22, respectively. The common flow channel 12 is defined by the second surface 172 of the first substrate 17 and the second flow channel member 19 stacked thereon, and is connected to a plurality of circulating flow channels 7e via the supply-side through flow channel 21 and the discharge-side through flow channel 22, respectively.

[0110] like Figure 8A As shown, the supply-side through flow channel 21 is connected to multiple inflow ports 8 corresponding to multiple ink jet sections 40, and the discharge-side through flow channel 22 is connected to multiple outflow ports 9 corresponding to multiple ink jet sections 40.

[0111] like Figure 8B As shown, the first flow channel member 13, stacked on the first surface 171 of the first substrate 17, includes a plurality of partition walls 133 extending in the X direction between a plurality of energy generating elements 1, which are aligned in the Y direction corresponding to a plurality of ink ejection portions 40. The pressure chamber 3 and the circulating flow channel 7e are defined by: an orifice plate 16 in which the ejection nozzles 2 open, and the orifice plate being stacked on opposite sides of the first substrate 17 relative to the first flow channel member 13; the first surface 171 of the first substrate 17; and the partition walls 133.

[0112] The supply-side through flow channel 21 and the discharge-side through flow channel 22 can be formed by the second flow channel component 19, such as Figure 8B As shown, they share a common flow channel 12 extending along the nozzle row direction (Y direction). The first substrate 17 can be very thin because it is necessary to minimize the effects of pressure loss to ensure refilling into the nozzle 2. However, to suppress the effect of ink thickening due to recycling, the first substrate 17 can be very thick, allowing the path between the supply-side flow channel 21 and the discharge-side flow channel 22 to be extended, as shown. Figure 8B As shown.

[0113] On the contrary, such as Figure 8CAs shown, in the second flow channel member 19 stacked on the second surface 172 of the first substrate 17, a supply-side common flow channel 24 and a discharge-side common flow channel 25 can be formed, respectively penetrating the second flow channel member 19, and the supply-side common flow channel 24 and the discharge-side common flow channel 25 are then connected to each other outside the recording head. The supply-side common flow channel 24 is formed to extend along the jet nozzle row direction (Y direction) and is connected to a plurality of circulating flow channels 7e via a supply-side through flow channel 21. In the same manner, the discharge-side common flow channel 25 is formed to extend along the jet nozzle row direction and is connected to a plurality of circulating flow channels 7e via a discharge-side through flow channel 22. By dividing the flow channels provided in the second flow channel member 19 into a supply-side common flow channel 24 and a discharge-side common flow channel 25, the effect of suppressing ink thickening due to recirculation can be better anticipated.

[0114] Next, the circulating flow channel 7e in Embodiment 4 will be described, in which ink is supplied from the supply side to the pressure chamber 3 (e.g., through the flow channel 21) Figure 8A As shown), the ink is discharged through the discharge-side through-flow channel 22. As a mechanism for generating flow within the circulating flow channel 7e, the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 are disposed between the inlet port 8 and the energy generating element 1. In Embodiment 4, based on the principle of a circulation method using thermoelectric conversion elements as energy generating elements to form a circulating flow, such as... Figure 8A and Figure 8B As shown, a flow from the inlet port 8 to the outlet port 9 is generated in the circulating flow channel 7e, thereby circulating the ink.

[0115] In embodiment 4, the first thermoelectric conversion element 5 is disposed on a side closer to the energy generating element 1 than the second thermoelectric conversion element 6, such as... Figures 8A to 8C As shown, however, the present invention is not limited to this configuration. In other words, as in Embodiments 1 to 3, the configuration is not limited to the above configuration as long as a predetermined resistance relationship is established between the thermoelectric conversion elements 5 and 6 in the circulating flow channel 7e. In Embodiment 4, as in Embodiments 1 to 3, the first thermoelectric conversion element 5, as the main element, is disposed at the most effective position where the flow resistance ratio R1 / R2 is in the range of 0.05 to 0.4, and the second thermoelectric conversion element 6 is disposed as a secondary element.

[0116] Similarly, for the drive signal, as in Example 1, such as Figure 5C As shown, the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 are driven alternately at different timings.

[0117] Effect

[0118] As in Examples 1 to 3, by driving two thermoelectric conversion elements separately, local heating can be suppressed, and the flow rate can be increased compared to driving one thermoelectric conversion element at a high frequency.

[0119] In some cases of the three-dimensional flow channel configuration in Example 3, if the supply flow channel and the discharge flow channel are separated to prevent ink thickening due to recirculation, the flow channel needs to be long, which increases flow resistance and reduces circulation efficiency. On the other hand, in the configuration of Example 4, the supply flow channel and the discharge flow channel are located in the same row (straight flow channel configuration), so even if thermoelectric conversion elements are placed at multiple locations to increase flow rate, the effect of ink thickening due to recirculation can be suppressed.

[0120] Furthermore, the thermoelectric conversion element and the injection nozzle are arranged in the same row, so the injection nozzle can be arranged at a high density regardless of the position of the thermoelectric conversion element.

[0121] Example 5

[0122] Reference Figure 9 The cyclic configuration of the recording element substrate 4f according to Embodiment 5 of this disclosure is described, with a focus on aspects that differ from the recording element substrates of Embodiments 1 to 4. Matters not specifically described herein in Embodiment 5 are the same as those in the above embodiments.

[0123] Figure 9 This is a diagram depicting a portion of the flow channel near the injection nozzle according to Embodiment 5. In the configuration of Embodiment 4, each injection nozzle 2 is provided with a first thermoelectric conversion element 5 and a second thermoelectric conversion element 6. On the other hand, in Embodiment 5, as... Figure 9 As shown, a first thermoelectric conversion element 5 and a second thermoelectric conversion element 6 are provided for each of the multiple injection nozzles 2.

[0124] The circulating flow channel 7f includes an upstream flow channel 71f on which thermoelectric conversion elements 5 and 6 are disposed, and a downstream flow channel 72f on which ink jet sections 40 are disposed. The number of upstream flow channels 71f arranged in a row along the Y direction (corresponding to the multiple ink jet sections 40) is less than the number of downstream flow channels 72f arranged in a row along the Y direction (corresponding to the multiple ink jet sections 40). Among the multiple downstream flow channels 72f, some downstream flow channels 72f adjacent to each other in the Y direction are connected to a common inlet port 8 via a common upstream flow channel 71f. In other words, ink flowing in through an inlet port 8 passes through an upstream flow channel 71f, then branches into some downstream flow channels 72f adjacent to each other in the Y direction, and then is discharged through some outlet ports 9. This means that one of the multiple upstream flow channels 71f becomes a common flow channel, which is connected to each of the multiple downstream flow channels 72f that are adjacent to each other in the Y direction and are respectively arranged in relation to the multiple ink jet sections 40. Since the number of upstream flow channels 71f is less than the number of downstream flow channels 72f, the number of thermoelectric conversion elements 5 and 6 arranged in a row along the Y direction is less than the number of ink jet sections 40 arranged in a row along the Y direction.

[0125] In the configuration of Embodiment 5, the first thermoelectric conversion element 5 is disposed on the side closer to the injection nozzle 2, and the second thermoelectric conversion element 6 is disposed on the side farther away from the injection nozzle 2, and the first and second thermoelectric conversion elements are adjacent to each other in this state. However, for example, the second thermoelectric conversion element 6 may be disposed on the side closer to the injection nozzle 2, or multiple thermoelectric conversion elements may be arranged in a row. Figure 9 In the configuration shown, a first thermoelectric conversion element 5 and a second thermoelectric conversion element 6 are provided for each group of two spray nozzles, but it is also possible to provide a first thermoelectric conversion element 5 and a second thermoelectric conversion element 6 for a group of three or more spray nozzles.

[0126] Effect

[0127] In the configuration of Embodiment 5 described above, a first thermoelectric conversion element 5 and a second thermoelectric conversion element 6 are provided for a group of multiple injection nozzles 2. Therefore, the resolution of thermoelectric conversion elements 5 and 6 is lower than the resolution of the injection nozzles 2. Since this allows for an increase in the size of thermoelectric conversion elements 5 and 6, the energy efficiency in the cycle can be improved.

[0128] Furthermore, as in Example 5, when the energy generating element used to form the circulating flow is a thermoelectric conversion element, there is a problem: if ink thickening occurs in the feed flow channel, the vapor bubbles generated on the thermoelectric conversion element become smaller as the ink viscosity increases, which reduces the circulation frequency. On the other hand, in the configuration of Example 5, a feed flow channel is provided for each group of multiple injection nozzles, thus widening the channel width of the feed flow channel, which can suppress resistance within the feed flow channel and minimize the decrease in circulation efficiency.

[0129] Furthermore, according to Embodiment 5, as in Embodiments 1 to 4 above, two thermoelectric conversion elements are driven separately, thus suppressing local heating and increasing flow rate compared to driving one thermoelectric conversion element at a high frequency.

[0130] Example 6

[0131] Reference Figure 10 The driving signal of the thermoelectric conversion element on the recording element substrate according to Embodiment 6 of this disclosure is described, with a focus on aspects that differ from Embodiments 1 to 5. Matters in Embodiment 6 not specifically described herein are the same as those in the above embodiments.

[0132] Figure 10 The driving timing of the voltage pulse applied to the thermoelectric conversion element is indicated according to Embodiment 6. In this configuration, it is assumed that the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 are adjacent to each other (the thermoelectric conversion elements form a pair). First, as in Embodiments 1 to 5, the first thermoelectric conversion element 5 is set at the optimal position where the flow rate becomes the highest, and then the first thermoelectric conversion element 5 is driven multiple times at a high frequency of 50 kHz. Then, the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 are driven at driving frequencies of f1x = f2x = 10 kHz, respectively. Here, the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 are driven alternately until the local temperature of the first thermoelectric conversion element 5 driven at the high frequency reaches a level that affects bubbling.

[0133] In other words, in the drive control according to Embodiment 6, a first drive period and a second drive period are set. In the first drive period, the first thermoelectric conversion element 5 is driven repeatedly only multiple times. In the second drive period, the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 are driven alternately. Furthermore, for the first thermoelectric conversion element 5, while driving it multiple times from the first drive period to the second drive period, the drive frequency of the first thermoelectric conversion element 5 is changed. Specifically, the first thermoelectric conversion element 5 is driven at a relatively high frequency (first frequency) in the first drive period, and then driven at a relatively low frequency (second frequency) in the subsequent second drive period.

[0134] Therefore, the thickened ink is supplied to the circulating flow channel at a faster ink flow rate, and after the thickened ink has flowed out to a certain extent, the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6 are driven at a lower driving frequency, respectively. Thus, while suppressing local temperature rise, the efficiency of circulating the thickened ink around the jet nozzle is improved.

[0135] As described above, the problem with using a thermoelectric conversion element as the energy generating element to form the circulating flow is that the vapor bubbles generated on the thermoelectric conversion element become smaller due to the thickening of the ink in the circulating flow channel, resulting in a decrease in the circulation frequency. On the other hand, in Embodiment 6, by initially driving at a high frequency, the thickened ink on the thermoelectric conversion element is rapidly replaced by fresh ink, thus suppressing the decrease in the efficiency of the thermoelectric conversion element.

[0136] In the case of Embodiment 2, in a configuration that includes a third thermoelectric conversion element 10 in addition to the first thermoelectric conversion element 5 and the second thermoelectric conversion element 6, the following control can be performed. In other words, a first driving period and a second driving period can be set. In the first driving period, the first thermoelectric conversion element 5 is driven repeatedly only multiple times. In the second driving period, the first thermoelectric conversion element 5, the second thermoelectric conversion element 6, and the third thermoelectric conversion element 10 are driven sequentially and repeatedly. Furthermore, for the first thermoelectric conversion element 5, its driving frequency can be changed while it is driven multiple times from the first driving period to the second driving period. Specifically, the first thermoelectric conversion element 5 is driven at a relatively high frequency (first frequency) in the first driving period, and then driven at a relatively low frequency (second frequency) in the subsequent second driving period.

[0137] The configurations of the above embodiments can be combined with each other.

[0138] According to the above disclosure, in a liquid jet head configured to circulate liquid using an energy-generating element, circulation efficiency can be improved.

[0139] While this disclosure has been described with reference to embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. The scope of the appended claims is to be given the broadest interpretation in order to cover all such modifications and equivalent structures and functions.

Claims

1. A liquid injection head, comprising: A liquid injection section includes: a pressure chamber; an injection nozzle for injecting liquid from the pressure chamber; and an energy generating element for generating energy to inject liquid from the pressure chamber from the injection nozzle. A circulating flow channel includes: an inlet port through which liquid to be supplied to the pressure chamber flows; and an outlet port through which liquid collected from the pressure chamber flows out, wherein the pressure chamber is disposed between the inlet port and the outlet port. A first thermoelectric conversion element is disposed on the circulating flow channel on a side closer to the inflow port than the energy generating element; and A second thermoelectric conversion element is disposed on the circulating flow channel on a side closer to the inlet port than the energy generating element, and the second thermoelectric conversion element is disposed adjacent to the first thermoelectric conversion element. The first thermoelectric conversion element and the second thermoelectric conversion element are driven at different timings.

2. The liquid injection head according to claim 1 further includes a third thermoelectric conversion element, the third thermoelectric conversion element being disposed on the circulating flow channel on a side closer to the inlet port than the energy generating element, and the third thermoelectric conversion element being disposed adjacent to the first thermoelectric conversion element on a side opposite to the second thermoelectric conversion element. The first thermoelectric conversion element, the second thermoelectric conversion element, and the third thermoelectric conversion element are driven at different timings.

3. The liquid injection head according to claim 1 or 2, The thermoelectric conversion element is an energy generating element that generates energy to make the liquid flow in the circulating flow channel.

4. The liquid injection head according to claim 1 or 2, In the circulating flow channel, the first flow resistance R1 between the inflow port and the thermoelectric conversion element is different from the second flow resistance R2 between the outflow port and the thermoelectric conversion element.

5. The liquid injection head according to claim 1 or 2, The spray nozzle is open in a first direction. Both the inlet port and the outlet port are located on one side of the liquid jet section in a second direction intersecting the first direction, and are arranged in a row in a third direction intersecting both the first and second directions. The circulating flow channel includes: - An upstream flow channel, which extends from the inflow port along the second direction from one side to the other; as well as - A downstream flow channel that extends from the other side to the first side along the second direction by turning its direction to the opposite direction to that of the upstream flow channel. The thermoelectric conversion element is disposed on the upstream flow channel, and The liquid injection section is located on the downstream flow channel.

6. The liquid injection head according to claim 5 further includes a common flow channel, the common flow channel being in communication with each of the inlet port and the outlet port. The liquid injection portion is arranged at multiple locations aligned along the third direction. The upstream flow channel extends along the second direction between the plurality of liquid injection sections in a manner that intersects with the rows of the plurality of liquid injection sections, and The common flow channel is disposed on one side of the inflow port and the outflow port along the second direction, so as to extend along the third direction and communicate with each of the plurality of inflow ports and the plurality of outflow ports disposed corresponding to the plurality of liquid injection portions.

7. The liquid injection head according to claim 6, The plurality of energy generating elements and the plurality of first thermoelectric conversion elements corresponding to the plurality of liquid injection portions are alternately arranged in a manner aligned along the third direction.

8. The liquid injection head according to claim 6, further comprising: A substrate in which the liquid jetting portion, the circulating flow channel, and the thermoelectric conversion element are disposed on a first surface side; A flow channel forming member is stacked on the first surface of the substrate and includes a partition wall that forms part of the circulating flow channel; as well as An orifice plate, wherein the injection nozzle is disposed in the orifice plate, and the orifice plate is stacked on the flow channel forming member on the side opposite to the substrate. The pressure chamber and the circulating flow channel are defined by the first surface of the substrate, the partition wall, and the perforated plate.

9. The liquid injection head according to claim 8, The first thermoelectric conversion element and the second thermoelectric conversion element are arranged adjacent to each other in the second direction at positions different from those of the energy generating element along the third direction. The partition wall includes: - A first partition wall portion, the first partition wall portion extending in the second direction, to define, in the third direction, the plurality of circulating flow channels corresponding to the plurality of liquid injection portions; as well as - A second partition wall portion, extending in the second direction, defines the energy generating element, the first thermoelectric conversion element, and the second thermoelectric conversion element on the separate circulating flow channel in the third direction. The second partition wall portion, on its side facing the third direction, forms part of the upstream flow channel, and The side of the second partition wall portion on the opposite side of the third direction forms part of the downstream flow channel and the pressure chamber.

10. The liquid injection head according to claim 8 or 9, The substrate includes a through-hole that is closer to one side in the second direction than the inflow port and the outflow port, and penetrates between the first surface of the substrate and the second surface, which is the rear surface of the first surface, in the first direction. The common flow channel is defined by the through hole, the flow channel forming member, and the orifice plate.

11. The liquid injection head according to claim 1 or 2, The spray nozzle is open in a first direction. The inflow port and the outflow port are arranged in a row along the first direction, and both are located on one side of the liquid jet section in a second direction that intersects the first direction; The circulating flow channel includes: - An upstream flow channel, which extends from the inflow port along the second direction from one side to the other; as well as - A downstream flow channel that extends from the other side to the first side along the second direction by turning its direction to the opposite direction to that of the upstream flow channel. The thermoelectric conversion element is disposed on the upstream flow channel, and The liquid injection section is located on the downstream flow channel.

12. The liquid injection head according to claim 11, The liquid injection section and the thermoelectric conversion element are located at different positions in the first direction.

13. The liquid injection head of claim 12, further comprising a common flow channel communicating with each of the inlet port and the outlet port. The liquid injection portion is disposed at multiple locations aligned along a third direction that intersects both the first and second directions. Each of the upstream flow channel and the downstream flow channel extends along the second direction and is arranged in a row along the first direction. The common flow channel is configured to be closer to one side in the second direction than the inflow port and the outflow port, so as to extend along the third direction and communicate with each of the plurality of inflow ports and the plurality of outflow ports that are provided corresponding to the plurality of liquid injection portions.

14. The liquid injection head according to claim 13, The plurality of circulating flow channels, which are provided corresponding to the plurality of liquid injection sections, are configured to be aligned along the third direction. The plurality of energy generating elements, which are arranged corresponding to the plurality of liquid injection sections, are aligned along the third direction. The plurality of first thermoelectric conversion elements, which are corresponding to the plurality of liquid injection portions, are arranged to be aligned along the third direction, and The plurality of second thermoelectric conversion elements, which are arranged corresponding to the plurality of liquid injection portions, are aligned along the third direction.

15. The liquid injection head according to claim 13, further comprising: A first substrate, comprising a first surface, a second surface, and a connecting hole, wherein the first surface on which the liquid injection portion is disposed constitutes part of the downstream flow channel and the pressure chamber, the second surface which is the rear surface of the first surface constitutes part of the upstream flow channel, and the connecting hole which penetrates between the first surface and the second surface along the first direction constitutes a connecting flow channel, the connecting flow channel connecting the upstream flow channel and the downstream flow channel on the circulating flow channel; A first flow channel forming member is stacked on the first surface of the first substrate and constitutes part of the downstream flow channel and the pressure chamber; An orifice plate, wherein the injection nozzle is disposed on the orifice plate, the orifice plate being stacked on the first flow channel forming member on the opposite side of the first substrate, and constituting part of the downstream flow channel and the pressure chamber; The second flow channel forming member is stacked on the second surface of the first substrate and constitutes part of the upstream flow channel; The second substrate is stacked on the second flow channel forming member on the opposite side of the first substrate. The second substrate has the first thermoelectric conversion element and the second thermoelectric conversion element disposed on the side facing the second flow channel forming member, and constitutes part of the upstream flow channel. as well as A common hole is provided, which is located closer to one side of the inflow port and the outflow port in the second direction. The common hole passes through the first flow channel forming member, the first substrate, the second flow channel forming member and the second substrate in the first direction in sequence, and forms the common flow channel.

16. The liquid injection head according to claim 1 or 2, The spray nozzle is open in the first direction. The inflow port is located on one side of the pressure chamber in a second direction that intersects the first direction. The outflow port is located on the other side of the pressure chamber in the second direction; The circulating flow channel extends along the second direction, such that the inlet port, the pressure chamber, and the outlet port are sequentially aligned along the second direction, and The thermoelectric conversion element is disposed on the circulating flow channel on the side closer to the inflow port than the energy generating element.

17. The liquid injection head of claim 16, further comprising a common flow channel communicating with each of the inlet port and the outlet port. The liquid injection portion is arranged at multiple locations aligned along a third direction that intersects both the first and second directions, and The common flow channel is connected to each of the plurality of inflow ports and the plurality of outflow ports that are provided corresponding to the plurality of liquid injection sections.

18. The liquid injection head according to claim 17, The plurality of circulating flow channels, which are provided corresponding to the plurality of liquid injection sections, are configured to be aligned along the third direction. The plurality of energy generating elements, which are arranged corresponding to the plurality of liquid injection sections, are aligned along the third direction. The plurality of first thermoelectric conversion elements, which are corresponding to the plurality of liquid injection portions, are arranged to be aligned along the third direction, and The plurality of second thermoelectric conversion elements, which are arranged corresponding to the plurality of liquid injection portions, are aligned along the third direction.

19. The liquid injection head according to claim 17 or 18, further comprising a substrate, wherein the liquid injection portion, the circulating flow channel, and the thermoelectric conversion element are disposed on the first surface side of the substrate. The substrate includes: - A supply-side through-flow channel extends through the substrate along the first direction between the first surface and a second surface that is the rear surface of the first surface, and the supply-side through-flow channel is closer to one side than the inflow port in the second direction; as well as - A discharge-side through-flow channel extends through the substrate between the first surface and the second surface along the first direction. The discharge-side through-flow channel is closer to the other side in the second direction than the outlet port. The common flow channel is formed on the second surface side of the substrate and is configured to communicate with each of the supply-side through flow channel and the discharge-side through flow channel.

20. The liquid injection head according to claim 19, The supply-side through-flow channel communicates with each of the plurality of inflow ports corresponding to the plurality of liquid injection sections, and The discharge-side through-flow channel is connected to each of the plurality of outflow ports corresponding to the plurality of liquid injection sections.

21. The liquid injection head according to claim 19, further comprising: A flow channel forming member is stacked on the first surface of the substrate, the flow channel forming member including a plurality of partition walls extending along a second direction between a plurality of energy generating elements, the plurality of energy generating elements being aligned with the plurality of liquid jet portions along the third direction. as well as An orifice plate, wherein the injection nozzle is disposed in the orifice plate, and the orifice plate is stacked on the flow channel forming member on the opposite side of the substrate, wherein... The pressure chamber and the circulating flow channel are defined by the first surface of the substrate, the partition wall, and the perforated plate.

22. The liquid injection head of claim 21, further comprising a second flow channel forming member, the second flow channel forming member being stacked on the second surface of the substrate, wherein the flow channel forming member is used as the first flow channel forming member. The second flow channel forming member and the second surface define the common flow channel, and The common flow channel is connected to each of the plurality of circulating flow channels via the supply-side through flow channel and the discharge-side through flow channel.

23. The liquid injection head according to claim 21, further comprising: A second flow channel forming member is stacked on the second surface of the substrate, and the flow channel forming member is used as a first flow channel forming member. The second flow channel forming member and the second surface define the common flow channel, and The public flow channel mentioned above includes: - A supply-side common flow channel, which is connected to each of the plurality of circulating flow channels via the supply-side through flow channel; and - A discharge-side common flow channel, which is connected to each of the plurality of circulating flow channels via the discharge-side through flow channel.

24. The liquid injection head according to claim 17 or 18, The circulating flow channel includes: - Upstream flow channel, wherein the thermoelectric conversion element is disposed on the upstream flow channel; as well as - Downstream flow channel, the liquid injection section is disposed on the downstream flow channel. The plurality of upstream flow channels corresponding to the plurality of liquid injection sections are configured such that one of the upstream flow channels is a common flow channel, and the common flow channel is connected to each of the plurality of downstream flow channels corresponding to the plurality of liquid injection sections that are adjacent to each other in the third direction. The number of the plurality of upstream flow channels arranged in a row along the third direction is less than the number of the plurality of liquid injection portions arranged in a row along the third direction, and The number of the plurality of thermoelectric conversion elements arranged along the third direction corresponding to the plurality of liquid injection portions is less than the number of the plurality of liquid injection portions arranged in a row along the third direction.

25. The liquid injection head according to claim 1 or 2, The first thermoelectric conversion element and the second thermoelectric conversion element are driven alternately and repeatedly.

26. The liquid injection head according to claim 2, The first thermoelectric conversion element, the second thermoelectric conversion element, and the third thermoelectric conversion element are driven repeatedly in sequence.

27. The liquid injection head according to claim 1 or 2, The first thermoelectric conversion element and the second thermoelectric conversion element include: - First driving period, during which only the first thermoelectric conversion element is driven multiple times; as well as - Second driving period, in which the first thermoelectric conversion element and the second thermoelectric conversion element are driven alternately and repeatedly.

28. The liquid injection head according to claim 2, The first thermoelectric conversion element, the second thermoelectric conversion element, and the third thermoelectric conversion element include: In the first driving period, only the first thermoelectric conversion element is driven repeatedly. as well as During the second driving period, the first thermoelectric conversion element, the second thermoelectric conversion element, and the third thermoelectric conversion element are driven repeatedly in sequence.

29. The liquid injection head according to claim 27, The driving frequency of the first thermoelectric conversion element changes while it is repeatedly driven multiple times.

30. The liquid injection head according to claim 4, wherein The flow resistance ratio R1 / R2 between the first flow resistance R1 and the second flow resistance R2 is 0.05 to 0.

4.

31. A liquid jetting device, comprising: The liquid injection head according to claim 1 or 2; as well as The control section controls the driving of the thermoelectric conversion element.

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