JP7086799B2 - Liquid supply device and liquid discharge device - Google Patents

Description

The present invention relates to a liquid supply device and a liquid discharge device that supply a liquid to a liquid discharge head capable of discharging a liquid such as ink.

Patent Document 1 describes a configuration in which ink in a recording head is circulated in a recording device (liquid ejection device) using a recording head (liquid ejection head) capable of ejecting ink (liquid) from an ejection port. Specifically, the pressure in the supply flow path that supplies ink to the recording head is controlled to a constant supply pressure by the decompression type regulator mechanism, and the pressure in the recovery flow path that collects ink from the recording head by the back pressure type regulator mechanism. Is controlled to a constant recovery pressure lower than the supply pressure. The differential pressure between the supply pressure and the recovery pressure circulates the ink in the recording head through the supply flow path and the recovery flow path to remove foreign substances such as air bubbles in the recording head and eject the ink. Reliability can be improved.

Patent No. 5731657

In the recording apparatus of Patent Document 1, ink refilling for the recording head is performed through the supply flow path. Further, the back pressure type regulator mechanism provided in the recovery flow path is configured to prevent backflow of ink (ink refill) from the recovery flow path to the recording head. Therefore, for example, at the time of high-duty recording in which a large amount of ink is ejected to a unit recording area in a short time, the ink refill becomes insufficient only from the supply flow path, and the pressure in the recording head partially fluctuates greatly. There is a risk. Specifically, of the plurality of ejection ports in the recording head, the ejection port that repeats the ink ejection operation has a higher negative pressure on the downstream side in the ink circulation direction than the ejection port. Due to the negative pressure, the flow rate of the refill ink passing near the other ejection ports in the non-ejection state of the ink increases, and the negative pressure in the recording head partially fluctuates. Such pressure fluctuations in the recording head may cause the ink ejection state to become unstable, resulting in deterioration of the quality of the recorded image. Such deterioration in the quality of the recorded image becomes more remarkable as the number of ejection ports in the recording head increases and the number of ejection ports in the non-ejection state during high-duty recording increases.

An object of the present invention is to improve the refillability of the liquid with respect to the liquid discharge head while maintaining the liquid circulation function in the liquid discharge head, and to stabilize the liquid discharge state in the liquid discharge head.

The liquid supply device of the present invention is a liquid supply device that supplies liquid to a liquid discharge head capable of discharging liquid in a pressure chamber from a discharge port, and is a liquid supply flow path communicating with the pressure chamber and the pressure chamber. The recovery flow path of the liquid communicating with the liquid, the first pressure control unit that controls the pressure in the supply flow path to the first pressure, and the pressure in the recovery flow path are controlled to the second pressure lower than the first pressure. Including the second pressure control unit, the liquid is supplied from the supply flow path to the pressure chamber, and the liquid in the pressure chamber is recovered from the recovery flow path in the supply flow path and the recovery flow path. A pressure control means that causes a pressure difference between the inside and the inside, and when the pressure in the recovery flow path is equal to or lower than a predetermined pressure, a liquid is supplied from the recovery flow path to the pressure chamber to enter the recovery flow path. It is characterized by including a pressure compensating means for compensating for a decrease in pressure and a suction pump arranged at a position downstream of the second pressure control unit in the liquid recovery direction by the recovery flow path.

According to the present invention, the liquid in the liquid discharge head is circulated through the liquid supply flow path and the liquid recovery flow path, and the liquid is also supplied from the liquid recovery flow path according to the state of the liquid discharge head. As a result, the refillability of the liquid with respect to the liquid discharge head can be improved, and the discharge state of the liquid discharge head can be stabilized.

It is a schematic block diagram of the whole of the recording apparatus in 1st Embodiment of this invention. It is explanatory drawing of the different state of the ink flow path in the recording apparatus of FIG. It is explanatory drawing of the different state of the ink flow path in the recording apparatus of FIG. It is a perspective view of the unit including the recording head of FIG. It is an exploded perspective view of the unit including the recording head of FIG. It is explanatory drawing of the flow path member which constitutes the ink ejection unit of FIG. It is an enlarged view of the VII part in FIG. FIG. 7 is a cross-sectional view taken along the line VIII-VIII of FIG. It is a perspective view of the discharge module in FIG. It is explanatory drawing of the element substrate in FIG. It is sectional drawing which follows the XI-XI line of FIG. It is an enlarged view of the adjacent part of the element substrate in FIG. It is explanatory drawing of the negative pressure control unit in FIG. FIG. 3 is an explanatory diagram of the relationship between the flow resistance and the valve opening degree in the negative pressure control unit of FIG. It is explanatory drawing of the different state of the ink flow path in the recording apparatus of 2nd Embodiment of this invention. It is explanatory drawing of the different state of the ink flow path in the recording apparatus of 3rd Embodiment of this invention. It is explanatory drawing of the different state of the ink flow path in the recording apparatus of 4th Embodiment of this invention. It is explanatory drawing of the different state of the ink flow path in the recording apparatus of 5th Embodiment of this invention. It is explanatory drawing of the different state of the ink flow path in the recording apparatus of 6th Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiment is an application example as an inkjet recording device (liquid ejection device) that ejects ink as a liquid from an inkjet recording head as a liquid ejection head and records an image.

(First Embodiment)
1. 1. Schematic Configuration of Recording Device FIG. 1A is a schematic perspective view of the inkjet recording device (liquid ejection device) 1100 according to the present embodiment. The recording device 1100 includes a transport unit 1004 that transports the recording medium P in the direction of arrow X, an ink ejection unit (liquid ejection unit) 300 including an inkjet recording head (liquid ejection head) 1, and an ink circulation unit (liquid circulation unit). It is equipped with 400. The configuration of the transport unit 1004 is arbitrary, such as a method using a transport belt as in this example, or a method using a transport roller, for example. The ink ejection unit 300 includes a line-type inkjet recording head (liquid ejection head) 1 extending in a direction intersecting (in this example, orthogonal) with the conveying direction (arrow X direction) of the recording medium P. A plurality of discharge ports are formed in the recording head 1, and these discharge ports form a discharge port row extending in a direction intersecting (in this example, orthogonal to) the transport direction of the recording medium P. It is arranged like this. The recording head 1 includes an ejection energy generating element such as an electric heat conversion element (heater) or a piezo element in order to eject ink from the ejection port. When the electric heat conversion element is provided, the ink can be foamed by the heat generated by the electric heat conversion element, and the ink can be ejected from the ejection port by utilizing the foaming energy.

The recording device 1100 of this example is a so-called full-line recording device, and the transfer unit 1004 continuously conveys a plurality of recording media P while ejecting ink from the ejection port of the recording head 1. Images can be continuously recorded on the recording medium P. The recording device 1100 records an image with reciprocating movement of the recording head 1 in a direction intersecting the transport direction of the recording medium P and intermittent transport operation of the recording medium P by the transport unit 1004, that is, a so-called serial scan. It may be a type recording device. The recording medium P is not limited to cut paper, and may be continuous roll paper. The recording head 1 can record a full-color image by ejecting cyan (C), magenta (M), yellow (Y), and black (K) inks. Ink is supplied and circulated to the recording head 1 as described later. Further, an electric control unit for transmitting electric power and ink ejection control signals is electrically connected to the recording head 1.

FIG. 1B is a block diagram of a control system of the recording device 1100. The CPU (control unit) 500 executes control processing and data processing of the operation of the entire recording device 1100 including the ink ejection unit 300, the ink circulation unit 400, and the transport unit 1004. Programs such as those processing procedures are stored in the ROM 501, and the RAM 502 is used as a work area or the like for executing those processes. The CPU 500 can record an image on the recording medium P by ejecting ink from the recording head 1 of the ink ejection unit 300 based on the image data input from the external host device 503 or the like.

2. 2. Ink flow path FIG. 2A is an explanatory diagram of an ink flow path corresponding to ink for one color in the recording device 1100, and the recording device 1100 in the figure is in a standby state (non-recording state) for recording operation. be.

The replaceable tank 20 has an outside air communication hole 26, and the ink contained therein is supplied through the pressurizing pump 1003 and the filter 1001. Further, the tank 20 is connected to the suction pump 1000 so as to collect the ink.

The ink supplied from the tank 20 is once pressurized by the pressurizing pump 1003, then passes through the filter 1001 and passes through the first pressure control mechanism (first pressure control unit) of the negative pressure control unit (pressure control unit) 3. The pressure is adjusted to a predetermined negative pressure by 31. After that, the ink passes through the supply valve 6 and then is supplied to the common supply flow path 12 formed in the recording head 1. After that, the ink flows from the common recovery flow path 13 to the second pressure adjusting mechanism (second pressure control unit) 32 of the negative pressure control unit 3 via a flow path described later formed in the recording element substrate 10. After entering, it is sucked by the suction pump 1000 and returned to the tank 20. The passive valve 33, the on-off valve 34, and the bypass valve 35 are closed in the standby state of the recording operation, and these functions will be described later.

The first pressure control mechanism (H) 31 and the second pressure control mechanism (L) 32 of the negative pressure control unit 3 are a so-called decompression type regulator mechanism and a back pressure type regulator mechanism, respectively. As will be described later, these control mechanisms 31 and 32 are downstream of the control mechanism 31 and upstream of the control mechanism 32 even when the ink passing flow rate fluctuates due to the action of the valves and spring members inside each of them. The ink pressure on the side can be stabilized within a certain range. The control pressure of the second pressure control mechanism 32 is set lower than the control pressure of the first pressure control mechanism 31. As a result, in the recording head 1, the ink flows from the common supply flow path 12 through the recording element substrate (hereinafter, also referred to as “element substrate”) 10 toward the common recovery flow path 13 (FIG. 2 (a). ) Flow in the direction of the white arrow) occurs. This ink flow causes an ink flow in each element substrate 10 in a non-recording state, and foreign matter such as bubbles and thickening ink can be discharged to the tank 20. Therefore, in order to eject these foreign substances from the ejection port of the recording head 1, it is not necessary to eject ink that does not contribute to image recording from the ejection port (preliminary ejection), and the ejection operation of the recording head 1 is performed. It can increase reliability.

The flow rate of the ink passing through the element substrate 10 can be set within a range in which such foreign matter can be discharged. On the other hand, in a general recording head, since the width of the flow path in the vicinity of the ejection port is an extremely fine microchannel of several tens of μm or less, the pressure loss of the ink passing through the element substrate 10 is extremely large. Therefore, if the flow rate of the ink in the element substrate 10 is too large, the negative pressure in the vicinity of the ejection port becomes too large, and there is a possibility that the meniscus of the ink suitable for the ink ejection operation cannot be held. In the case of the element substrate 10 in which the ejection ports are arranged at a high density so that the ejection port spacing is 600 dpi or more, the ink flow rate is the ink at the time of total ejection of ink (when ink is ejected from all ejection ports at the same time). It is preferable to set it smaller than the discharge amount of.

3. 3. Negative pressure fluctuation compensation function FIG. 2 (b) shows a high-duty recording state in which a large amount of ink is ejected to a unit recording area in a short time, and ink is ejected from the ejection ports of all the element substrates 10. It is explanatory drawing of the flow of ink in the state of a large amount.

As described above, from the viewpoint of preventing the generation of excessive negative pressure in the vicinity of the ejection port, the flow rate of the ink passing through the element substrate 10 in the non-recording operation should be set smaller than the ejection amount at the time of total ejection of the ink. Is preferable. However, when this setting is made, not only the ink refill flow from the common supply flow path 12 but also the common recovery is performed with respect to the ejection port as shown by the white arrow in FIG. 2B at the time of high duty recording. An ink refill flow is also generated from the flow path 13 side.

As will be described later, the second pressure control mechanism (back pressure type regulator) 32 is configured so that backflow of ink does not occur even in such a case. Further, the suction pump 1000 is also configured so that backflow of ink does not occur. Therefore, when high-duty recording is continued by all the recording element substrates, the pressure in the recovery flow path between the tank 20 and the common recovery flow path 13 gradually decreases, and eventually the ink refill for the ejection port is insufficient. May occur. In this case, the volume of the ink droplets ejected from the ejection port becomes smaller than the initial value at the time of design, and the recording density of the image is lowered and the image is blurred. Further, when a part of the element substrate 10 is in the non-recording state, or when it is in the low duty recording state in which a small amount of ink is ejected to the unit recording area in a short time, the element substrate 10 of the part thereof. The ink passing flow rate near the ejection port may increase. In this case, the negative pressure in the vicinity of the discharge port in a part of the element substrate 10 increases and the temperature abnormally decreases, so that the image quality of the recorded image also deteriorates.

Therefore, in the present invention, the negative pressure compensating mechanism (pressure compensating unit) is located between the downstream side of the first pressure control mechanism 31 in the ink supply direction and the upstream side of the second pressure control mechanism 32 in the ink recovery direction. 37 is connected. The negative pressure compensation mechanism communicates the supply flow path between the first pressure control mechanism 31 and the common supply flow path 12 and the recovery flow path between the second pressure control mechanism 32 and the common recovery flow path 13. A passive valve 33 and an on-off valve 34 are provided in the communication passage. The passive valve 33 opens so as to introduce the ink in the supply flow path into the recovery flow path when the pressure of the common recovery flow path 13 is equal to or lower than the predetermined pressure. The passive valve 33 of this example operates by the differential pressure between the predetermined pressure in the supply flow path controlled by the first pressure control mechanism 31 and the pressure in the recovery flow path. More specifically, the differential pressure between the supply flow path and the recovery flow path between the control pressure (high pressure) of the first pressure control mechanism 31 and the control pressure (low pressure) of the second pressure control mechanism 32 or more. The passive valve 33 is designed to open when a differential pressure is generated. By opening the on-off valve 34 that can be controlled to open and close during the recording operation, when the pressure of the common recovery flow path 13 falls below the control pressure of the second pressure control mechanism 32, the passive valve 33 opens and the supply flow. A communication passage between the path and the recovery flow path is formed, and an excessive increase in negative pressure in the vicinity of the discharge port is suppressed. Therefore, even during high-duty recording, ink can be stably ejected from the ejection port of each element substrate 10.

FIG. 3A is an explanatory diagram of ink flow when most of the element substrates 10 are in a high duty recording state and a small number of element substrates 10 are in a standby state for recording operation. For the element substrate 10 in the high duty recording state, an ink refill flow (flow in the direction of the white arrow pointing upward in FIG. 3A) is generated from the common recovery flow path 13. On the other hand, the ink that has passed through the element substrate 10 in the standby state is applied to such an ink refill flow. However, when the flow rate of the ink refill flow of the former is larger than the flow rate of the ink passing through the element substrate 10 in the latter standby state, the negative pressure in the common recovery flow path 13 increases. In this case, as in the case of FIG. 2B, the passive valve 33 opens to suppress the pressure drop in the common recovery flow path 13, and the insufficient ink is supplied through the passive valve 33 and the on-off valve 34. can do.

As described above, in the present invention, ink can be stably ejected from the ejection port of each element substrate 10 regardless of the recording state (recording duty).

If the negative pressure compensation mechanism 37 is not provided, the ink flow rate passing through the element substrate 10 in the standby state increases in order to make up for the shortage of the ink refill flow. Therefore, the flow rate of the ink passing near the ejection port of the recording element substrate in the standby state changes according to the recording state (recording duty) of the other recording element substrate. As shown in FIG. 3A, when the number of element substrates 10 in the standby state is small, the negative pressure rises and the temperature abnormally decreases in the vicinity of the discharge port of the element substrate 10 in the standby state. As a result, the volume of the ink droplets ejected from the ejection port changes from the desired value at the time of design, and the recorded image becomes uneven in density.

4. Strong recovery mode FIG. 3B shows the functions of the bypass flow path connecting the upstream side and the downstream side of the second pressure control mechanism 32 and the bypass valve 35 provided in the bypass flow path with controllable opening / closing. It is explanatory drawing.

By opening and controlling the bypass valve 35 in the strong recovery mode, the flow rate of ink passing through the recording head 1 is normally controlled according to the rotation speed of the suction pump 1000 regardless of the operation of the second pressure control mechanism 32. Can be more than. Therefore, in such a strong recovery mode, foreign matter (foam, thickening ink, etc.) in the vicinity of the ejection port and in the common recovery flow path 13 that could not be discharged by the normal flow rate of ink can be discharged. The flow rate of the ink in the strong recovery mode can be selected in consideration of the recoverability of discharging foreign matter within the range in which the meniscus of the ink at the ejection port can be held. Since this strong recovery mode is executed in the non-recording operation state, the ink flow rate is such that the negative pressure near the ejection port is equal to or higher than the appropriate negative pressure required to secure the ink ejection characteristics. good.

Such a strong recovery mode is different from the recovery operation (suction recovery and pressure recovery) for discharging foreign matter in ink from the ejection port, and while significantly reducing waste ink, the ejection port and the common recovery flow path. Foreign matter in 13 can be discharged. In this way, it is possible to reduce waste ink and simplify the mechanism (recovery mechanism) for recovery processing. Further, when executing such a strong recovery mode, it is necessary to control the on-off valve 34 to be closed. This is because, in the strong recovery mode, a larger differential pressure than usual is generated between the common supply flow path 12 and the common recovery flow path 13, so that the function of the negative pressure compensation mechanism 37 must be stopped by the on-off valve 34. This is because the differential pressure cannot be increased by the action of the passive valve 33. The function of the on-off valve 34 may be provided to the passive valve 33 itself. Further, it is preferable that the on-off valve 34 is closed even when the power of the recording device is turned off.

5. Configuration of Recording Head FIGS. 4A and 4B are perspective views of the recording head 1 in the present embodiment.

The recording head 1 of this example is a line-type recording head in which 15 element substrates 10 are linearly arranged (arranged inline). Each of the element substrates 10 is arranged with ejection ports capable of ejecting inks of four colors C, M, Y, and K. The element board 10 is electrically connected to the signal input terminal 91 and the power supply terminal 92 via the flexible wiring board 40 and the electric wiring board 90. The signal input terminal 91 and the power supply terminal 92 are electrically connected to the control unit of the recording device 1100, and the power required for discharging the discharge drive signal and ink is supplied to the element substrate 10 via the control unit. By consolidating the wiring of the electric circuit in the electric wiring board 90, the number of the signal input terminals 91 and the power supply terminals 92 can be reduced as compared with the number of the element boards 10. This makes it possible to reduce the number of electrical connections that need to be removed when assembling the recording head 1 to the recording device 1100 or when replacing the recording head 1.

As shown in FIG. 4B, the connecting portions 114 located at both ends of the recording head 1 are connected to the ink supply system of the recording device 1100 including the tank 20, the pressurizing pump 1003, and the suction pump 1000. As a result, as described above, ink of four colors C, M, Y, and K is supplied to the recording head 1 from the ink supply system of the recording device 1100, and the ink that has passed through the recording head 1 is supplied to the recording device 1100. It is collected in the ink supply system. In this way, the ink of each color is circulated through the ink flow path of the recording device 1100 and the ink flow path of the recording head 1.

FIG. 5 is an exploded perspective view of the ink ejection unit 300 including the recording head 1, the ink supply unit 220, and the ink circulation unit 400.

The ink ejection unit 300, the ink supply unit 220, and the electric wiring board 90 are attached to the housing 80. The ink supply unit 220 is provided with a connection portion 114 (see FIG. 4). Inside the ink supply unit 220, a filter 1001 (see FIG. 2) for each ink color that communicates with the opening of the connection portion 114 is provided in order to remove foreign matter in the supplied ink. The two ink supply units 220 are each provided with a filter 1001 for two colors of ink. The ink that has passed through the filter 1001 is supplied to the negative pressure control unit 3 arranged on the ink supply unit 220 corresponding to each ink color. A total of four negative pressure control units 3 are provided so as to correspond to each ink color. As shown in FIG. 2, a first pressure control mechanism (H) 31 and a second pressure control mechanism (L) 32 are configured in each negative pressure control unit 3. As will be described later, these control mechanisms 31 and 32 have changes in pressure loss in the ink supply system of the recording device 1100 caused by fluctuations in the ink flow rate due to the functions of valves and spring members provided inside the control mechanisms 31 and 32. Is greatly attenuated. As a result, the change in negative pressure in the flow path of the ink ejection unit 300 can be stabilized within a certain range.

The housing 80 supports the ink ejection unit 300 by the support portion 81, supports the electric wiring board 90 by the support portion 82, and secures the rigidity of the entire recording head 1. The support portion 82 that supports the electric wiring board 90 is fixed to the support portion 81 that supports the ink ejection unit 300 with screws. The support portion 81 corrects the warp and deformation of the ink ejection unit 300 to ensure the relative position accuracy of the plurality of element substrates 10, thereby suppressing the occurrence of streak-like defects and density unevenness in the recorded image. Therefore, the support portion 81 preferably has sufficient rigidity, and as the material thereof, for example, a metal material such as SUS or aluminum, or a ceramic such as alumina is suitable. The support portion 81 is provided with openings 83, 84 for inserting the joint rubber 100. The ink supplied from the ink supply unit 220 is guided to the third flow path member 70 constituting the ink ejection unit 300 through the holes in the joint rubber 100.

The ink ejection unit 300 includes a plurality of ejection modules 200 and a flow path member 210, and a cover member 130 is attached to a surface of the ink ejection unit 300 on the recording medium side. The cover member 130 is a frame-shaped member provided with a long opening 131, and the element substrate 10 and the sealing material 110 (see FIG. 9A) included in the discharge module 200 are exposed from the opening 131. do. The frame portion around the opening 131 in the cover member 130 functions as a contact surface with which the cap member capping the recording head 1 abuts during recording standby. It is preferable to apply an adhesive, a sealing material, a filler, or the like along the periphery of the opening 131 to fill the unevenness and gaps on the surface of the ink ejection unit 300 where the ejection port is formed. This makes it possible to form a closed space inside the cap member during capping by the cap member.

The flow path member 210 is a stack of a first flow path member 50, a second flow path member 60, and a third flow path member 70. The flow path member 210 distributes the ink supplied from the ink supply unit 220 to the ejection module 200, and returns the ink from the ejection module 200 to the ink supply unit 220. The flow path member 210 is fixed to the support portion 81 of the housing 80 with screws, whereby warpage and deformation of the flow path member 210 are suppressed.

6 (a) and 6 (b) are front and back views of the first flow path member 50, and FIGS. 6 (c) and 6 (d) are front and back views of the second flow path member 60, FIG. (E) and (f) are a front view and a back view of the third flow path member 70. FIG. 6A shows the surface of the first flow path member 50 on which the discharge module 200 is mounted, and FIG. 6F shows the surface of the third flow path member 70 that abuts on the support portion 81 of the housing 80. Is shown. The first flow path member 50 and the second flow path member 60 are joined so that the surface of FIG. 6 (b) and the surface of FIG. 6 (c) face each other, and the second flow path member and the third flow path member are joined. Is joined so that the surface of FIG. 6 (d) and the surface of FIG. 6 (e) face each other.

When the second flow path member 60 and the third flow path member 70 are joined, a total of 8 extending in the longitudinal direction of the flow path members 60, 70 by the common flow path grooves 62, 71 on the joint surface thereof. Two common channels are formed. As a result, a common supply flow path 12 and a common recovery flow path 13 are formed inside the flow path member 210 for each color of ink. The communication port 72 of the third flow path member 70 fluidly circulates with the ink supply unit 220 through the corresponding hole of the joint rubber 100. In the second flow path member 60, a plurality of communication ports 61 are formed on the bottom surface of the common flow path groove 62, and these communication ports 61 are the individual flow path grooves 52 formed in the first flow path member 50. Communicate to one end. A communication port 51 is formed at the other end of the individual flow path groove 52, and the individual flow path groove 52 fluidly communicates with the plurality of discharge modules 200 through the communication port 51. With this individual flow path groove 52, the flow path can be intensively formed at the position on the center side of the flow path members 50, 60, 70.

The first, second, and third flow path members 50, 60, and 70 are preferably made of a material having corrosion resistance to ink and having a low coefficient of linear expansion. The material is a composite material (resin material) using alumina, LCP (liquid crystal polymer), PPS (polyphenyl sulfide), PSF (polysulfone) as a base material and adding an inorganic filler (fine particles, fibers, etc.) of silica or alumina. Can be used. As a method for forming the flow path member 210, three flow path members 50, 60, and 70 may be laminated and bonded to each other, and when a resin composite resin material is selected as the material of these members, welding is performed. A joining method may be used.

FIG. 7 shows a flow path in the flow path member 210 formed by joining the first, second, and third flow path members 50, 60, and 70 from the surface of the first flow path member 50 in FIG. 6A. It is a perspective view and corresponds to the enlarged view of the VIIa portion of FIG. 6A.

The flow path member 210 includes a common supply flow path 12 (12a, 12b, 12c, 12d) extending in the longitudinal direction of the recording head 1 and a common recovery flow path 13 (13a, 13b, 13c, 13d) for each ink color. Is formed. A plurality of first individual flow paths (213a, 213b, 213c, 213d) formed by the individual flow path grooves 52 are connected to the common supply flow path 12 (12a, 12b, 12c, 12d) via the communication port 61. Will be done. A plurality of second individual flow paths (214a, 214b, 214c, 214d) formed by the individual flow path grooves 52 are connected to the common recovery flow path 13 (13a, 13b, 13c, 13d) via the communication port 61. Will be done. With such a flow path configuration, ink can be intensively supplied to the element substrate 10 located at the center of the flow path member 210 through the common supply flow path 12 and the first individual flow path 213. Ink can be recovered from the element substrate 10 to the common recovery flow path 13 through the second individual flow path 214.

FIG. 8 is a cross-sectional view taken along the line VIII-VIII of FIG.

In FIG. 8, the second individual flow paths 214a and 214c communicate with the discharge module 200 through the communication port 51. The same applies to the other second individual flow paths 214b and 214d. Further, as shown in FIG. 7, the first individual flow path 213 also communicates with the discharge module 200 through the communication port 51. The support member 30 and the element substrate 10 included in the ejection module 200 are formed with a supply flow path for supplying the ink from the first flow path member 50 to the pressure chamber 123 (see FIG. 11) of the element substrate 10. There is. Further, the support member 30 and the element substrate 10 are formed with a recovery flow path for recovering (circulating) a part or all of the ink in the pressure chamber to the first flow path member 50.

The common supply flow path 12 for each ink color is connected to the first pressure control mechanism (H) 31 on the high pressure side in the corresponding negative pressure control unit 3 via the ink supply unit 220. Further, the common recovery flow path 13 for each ink color is connected to the second pressure control mechanism (L) 32 on the low pressure side in the corresponding negative pressure control unit 3 via the ink supply unit 220. As described above, the negative pressure control unit 3 creates a differential pressure (pressure difference) between the common supply flow path 12 and the common recovery flow path 13. As a result, in the recording head 1, ink flows from the common supply flow path 12 to the first individual flow path 213, the element substrate 10, the second individual flow path 214, and the common recovery flow path 13. ..

6. Discharge module FIG. 9 (a) is a perspective view of one discharge module 200, and FIG. 9 (b) is an exploded view of the discharge module 200.

In manufacturing the discharge module 200, first, the element substrate 10 and the flexible wiring board 40 are bonded onto the support member 30 provided with the communication port 31 in advance. After that, the terminal 16 on the element substrate 10 and the terminal 41 on the flexible wiring board 40 are electrically connected by wire bonding, and then the wire bonding portion (electrical connection portion) is covered with the sealing material 110 and sealed. .. In the flexible wiring board 40, a terminal 42 is provided at a position opposite to the connection portion with the element board 10, and the terminal 42 is electrically connected to the connection terminal 93 (see FIG. 5) of the electric wiring board 90. Be connected. The support member 30 is a support that supports the element substrate 10, and is also a flow path member that fluidly communicates the element substrate 10 and the flow path member 210. Therefore, it is preferable that the support member 30 has a high flatness and can be bonded to the element substrate 10 with sufficiently high reliability, and as the material thereof, for example, alumina or a resin material is preferable.

7. Recording element substrate (element substrate)
10 (a) is a plan view of the element substrate 10 as viewed from the formation surface side of the discharge port 113, FIG. 10 (b) is an enlarged view of the Xb circle portion of FIG. 10 (a), and FIG. 10 (c) is. , The element substrate 10 is a plan view from the side opposite to FIG. 10A. As shown in FIG. 10A, a plurality of ejection ports 113 are formed in the ejection port forming member 112 of the element substrate 10, and these ejection ports 113 have a total of four rows of ejection port rows L corresponding to each ink color. Are arranged to form. Hereinafter, the direction in which the discharge port row L extends is also referred to as a “discharge port row direction”.

As shown in FIG. 10B, an electric heat conversion element (heater) 115 is provided as an ink ejection energy generating element at a position corresponding to the ejection port 113. The pressure chamber 123 in which the heater 115 is deployed is partitioned by a partition wall 122. The heater 115 is electrically connected to the terminal 16 of FIG. 10A by an electric wiring (not shown) formed on the element substrate 10. The heater 115 generates heat based on a pulse signal input from the control circuit of the recording device 1100 via the electric wiring board 90 (see FIG. 5) and the flexible wiring board 40 (see FIG. 9). The heat generated causes the ink in the pressure chamber 123 to foam, and the foaming energy is used to eject the ink from the ejection port 113. A supply path 18 extending along the discharge port row L is formed on one side of the discharge port row L, and a collection path 19 extending along the discharge port row L is formed on the other side of the discharge port row L. Is formed. The supply passage 18 and the recovery passage 19 communicate with the pressure chamber 123 through the supply port 17a and the recovery port 17b, respectively.

As shown in FIG. 10 (c), in the element substrate 10, a sheet-shaped lid member 120 is laminated on the surface of the element substrate 10 opposite to the surface on which the discharge port 113 is formed, and the supply path 18 and the supply path 18 and the lid member 120 are laminated. A plurality of openings 21 communicating with the collection path 19 are formed. In this example, three openings 21 are formed for one supply path 18, and two openings 21 are formed for one recovery path 19. As shown in FIG. 7, those openings 21 communicate with the communication port 51 of the first flow path member 50 in FIG. 6A. As shown in FIG. 11, the lid member 120 functions as a lid that forms a part of the wall of the supply path 18 and the recovery path 19 formed on the substrate 111. The lid member 120 preferably has sufficient corrosion resistance against ink, and from the viewpoint of preventing color mixing of ink, high accuracy is required for the opening shape and opening position of the opening 21. Since the lid member 120 changes the pitch of the ink flow path by the opening 21, it is preferable to make the lid member 120 thin from the viewpoint of pressure loss. As the lid member 120, for example, it is preferable to use a photosensitive resin material or a thin silicon plate, and it is preferable to form the opening 21 by a photolithography process.

FIG. 11 is a perspective view of the element substrate 10 of FIG. 10 (a) in cross section along XI-XI.

In the element substrate 10, a substrate 111 formed of Si and a discharge port forming member 112 formed of a photosensitive resin are laminated, and a lid member 120 is further bonded to the back surface of the substrate 111. A heater 115 is formed on the front surface side (upper side in FIG. 11) of the substrate 111, and extends along the discharge port row L on the back surface side (lower side in FIG. 11) of the substrate 111. A groove forming the supply path 18 and the recovery path 19 is provided. The supply path 18 and the recovery path 19 formed by the substrate 111 and the lid member 120 are connected to the common supply flow path 12 and the common recovery flow path 13 in the flow path member 210, respectively, and the supply path 18 and the recovery path are connected to each other. A differential pressure is generated between 19 and 19. When ink is ejected from a plurality of ejection ports 113 of the recording head 1 to record an image, the supply path 18 and the recovery path 19 are provided at the ejection port (discharge port during ejection suspension) 113 in which ink is not ejected. The differential pressure between them causes ink flow. That is, the ink in the supply path 18 in the substrate 111 flows to the recovery path 19 via the supply port 17a, the pressure chamber 123, and the recovery port 17b as shown by the arrow C in FIG. In the ejection port 113 during ejection suspension and the corresponding pressure chamber 123, foreign matter such as thickened ink and bubbles generated by evaporation of ink components from the ejection port 113 during ink ejection suspension is caused by this ink flow. , Can be collected through the collection path 19. In addition, thickening of ink in the ejection port 113 and the pressure chamber 123 can be suppressed.

The ink recovered in the recovery path 19 passes through the opening 21 of the lid member 120, the communication port 31 of the support member 30, the communication port 51 of the flow path member 210, the individual recovery flow path 214, and the common recovery flow path 13. Finally, it is collected in the tank 20.

That is, ink is supplied and recovered from the recording device main body to the recording head 1 as follows.

First, the ink supplied from the recording device main body flows into the inside of the recording head 1 from the connection portion 114 of the ink supply unit 220, and passes through the first pressure control mechanism 31 in the negative pressure control unit 3. , Adjusted to a relatively low negative pressure. The pressure-adjusted ink is the ink supply unit 220, the joint rubber 100, the communication port 72 and the common flow path groove 71 of the third flow path member 70, and the common flow path groove 62 and the communication port 61 of the second flow path member 60. The individual flow path groove 52 and the communication port 51 of the first flow path member 50 flow in this order. After that, the ink in the communication port 51 is supplied into the pressure chamber 123 through the communication port 31 of the support member 30, the opening 21 of the lid member 120, the supply path 18 of the substrate 111, and the supply port 17a. Of the ink supplied to the pressure chamber 123, the ink not discharged from the ejection port 113 flows through the recovery port 17b and the recovery path 19 of the substrate 111, the opening 21 of the lid member 120, and the communication port 31 of the support member 30. .. After that, the ink is applied to the communication port 51 and the individual flow path groove 52 of the first flow path member 50, the communication port 61 and the common flow path groove 62 of the second flow path member 60, and the common flow path of the third flow path member 70. It passes through the groove 71, the communication port 72, the joint rubber 100, and the ink supply unit 220. After that, the ink flows into the ink supply unit 220 again from the second pressure control mechanism 32 in the negative pressure control unit 3, and then is collected in the tank 20 outside the recording head 1 through the connection portion 114.

8. Positional Relationship between Recording Element Substrate (Element Substrate) FIG. 12 is an enlarged plan view of an adjacent portion of an element substrate 10 in two ejection modules 200 adjacent to each other. In this example, as shown in FIG. 10A, an element substrate 10 having a substantially parallelogram plane is used. As shown in FIG. 12, the discharge port rows L (L1, L2, L3, L4) in which the discharge ports 113 in the element substrate 10 are arranged are tilted at a constant angle with respect to the transport direction (arrow X direction) of the recording medium P. It is formed like this. As a result, at least one discharge port 113 overlaps the discharge port rows L in the adjacent portions of the element substrates 10 in the transport direction of the recording medium P. In the example of FIG. 12, the two discharge ports 113 on the D line along the X direction of the arrow overlap each other.

In such a positional relationship, by driving and controlling the heater 115 corresponding to the discharge port 113 that overlaps with each other in relation to each other, even if the deployment position of the element substrate 10 is slightly deviated from the predetermined position, black streaks in the recorded image can be generated. White spots can be made inconspicuous. The configuration as shown in FIG. 12 is effective not only when the plurality of element substrates 10 are arranged in a staggered pattern but also when they are arranged in a straight line (inline). That is, even when a plurality of element substrates 10 are arranged on a straight line, recording corresponding to a connecting portion (adjacent portion) between the element substrates 10 while keeping the length of the recording head 1 in the transport direction of the recording medium P small. It is possible to suppress the occurrence of black streaks and white spots in the image. Further, the shape of the element substrate 10 is not limited to the shape of a parallelogram having a plane as in this example. For example, the configuration of the present invention can be preferably applied even when the element substrate 10 having a rectangular, trapezoidal, or other shaped plane is used.

9. The first and second pressure adjusting mechanism FIG. 13 is an explanatory diagram of the negative pressure control unit 3 including the first pressure control mechanism 31 and the second pressure control mechanism 32. 13 (a) is a perspective view of the negative pressure control unit 3, FIG. 13 (b) is a cross-sectional view taken along the line XIIIb-XIIIb of FIG. 13 (a), and FIG. 13 (a) is XIIIc of FIG. 13 (a). -It is a cross-sectional view along the XIIIc line.

The first pressure control mechanism 31 as the decompression type regulator mechanism and the second pressure control mechanism 32 as the back pressure type regulator mechanism are configured in a common body 310, and they can be integrally attached and replaced. can. By arranging the two pressure control mechanisms 31 and 32 symmetrically with each other as shown in FIG. 13 (c), the space of the negative pressure control unit 3 can be saved.

9-1. First Pressure Control Mechanism The first pressure control mechanism 31 as a decompression type regulator mechanism has a first pressure chamber 305 located on one side (lower side in the figure) of the body 310 as shown in FIG. 13 (b). , A second pressure chamber 306 located on the other side of the body 310 (upper side in the figure). The first pressure chamber 305 is sealed by the flexible film 303A, and the second pressure chamber 306 is sealed by the pressure receiving plate 302 and the flexible film 303B. An orifice 308 is formed between the first pressure chamber 305 and the second pressure chamber 306. A valve 307 connected to the pressure receiving plate 302 by the shaft 304 is located in the first pressure chamber 305, and the shaft 304, the valve 307, and the pressure receiving plate 302 move integrally when the recording head 1 is driven. The pressure receiving plate 302 is urged by the urging member (spring) 301B in the direction in which the valve 307 closes the orifice 308. Further, the valve 307 is urged in the direction of closing the orifice 308 by the urging member (spring) 301A provided in the first pressure chamber 305, and the flexible film 303A is urged in the direction of being pressed against the negative pressure adjusting member 311. Will be done.

The main function of the valve 307 is to change the gap between the valve 307 and the orifice 308 to adjust the flow resistance of the ink. The valve 307 preferably closes the gap with the orifice 308 when the ink circulation is stopped. By fluidly sealing between the valve 307 and the orifice 308 when the ink circulation is stopped (when the recording operation is stopped), the negative pressure is continuously applied to the ink at the discharge port 113 from the discharge port 113. It is possible to prevent ink leakage. As the material of the valve 307, an elastic material such as rubber or an elastomer having sufficient corrosion resistance against ink is preferable.

In this example, the springs as the urging members 301A and 301B are two coupled springs. However, since it is sufficient that the desired negative pressure of the ink can be obtained by the combined spring force thereof, for example, a configuration using only one spring or a configuration using three or more springs can be adopted. In the example of FIG. 13B, one of the urging members 301A and 301B (two coupled springs) is provided separately in the second pressure chamber 306 to form the pressure receiving plate 302. It is configured so that it can be separated from the shaft 304. Even in a state where the pressure receiving plate 302 and the shaft 304 are separated, the urging force of the urging member 301B in the second pressure chamber 306 acts on the pressure receiving plate 302. Therefore, even when the valve 307 closes the orifice 308, the pressure receiving plate 302 is separated from the shaft 304 by the urging force of the urging member 301B in the second pressure chamber 306, and the volume in the second pressure chamber 306 is further increased. It is possible to move in the direction of increasing. As a result, when the recording head 1 is not driven for a long period of time and bubbles are taken into the recording head 1, the second pressure chamber 306 functions as a buffer for absorbing the volume increase of the bubbles for recording. It is possible to prevent the ink in the head 1 from becoming a positive pressure.

The first pressure chamber 305 and the second pressure chamber 306 communicate with the ink inlet 312A and the ink outlet 312B (see FIG. 13A), respectively. The valve 307 is located upstream of the orifice 308 in the ink flow direction, and the pressure receiving plate 302 moves upward in FIG. 13 (b) to reduce the gap between the valve 307 and the orifice 308. do. The ink that has entered the first pressure chamber 305 from the inflow port 312A flows into the second pressure chamber 306 through the gap between the valve 307 and the orifice 308, and the pressure of the ink is transmitted to the pressure receiving plate 302. .. The ink in the second pressure chamber 306 is supplied to the ink ejection unit 300 from the outlet 312B.

The pressure P2 in the second pressure chamber 306 is determined from the following relational expression (1) showing the balance of the forces applied to each part.
P2 = P0- (P1 ・ Sv + k1 ・ x) / Sd ・ ・ ・ (1)

Sd is the pressure receiving area of the pressure receiving plate 302, Sv is the pressure receiving area of the valve 307, P0 is the atmospheric pressure, P1 is the pressure in the first pressure chamber 305, and P2 is the pressure in the second pressure chamber 306. k1 is the spring constant of the urging member 301 (301A, 301B), and x is the displacement (spring displacement) of the urging member 301 (301A, 301B).

Since the second term on the right side of the above equation (1) is always a positive value, P2 <P0 and P2 is a negative pressure. By changing the urging force of the urging member 301 (301A, 301B), the pressure P2 in the second pressure chamber 306 can be set to a desired control pressure. The urging force of the urging member 301 can be changed according to the spring constant K and the spring length during operation.

The relationship of the following equation (2) is established between the ink flow resistance R in the gap between the valve 307 and the orifice 308 and the flow rate Q of the ink passing through the orifice 308.
P2 = P1-QR ... (2)

The gap between the valve 307 and the orifice 308 (hereinafter, also referred to as “valve opening”) and the flow resistance R have a relationship as shown in FIG. 13, for example, that is, the flow resistance R decreases as the valve opening increases. Set to the relationship. The valve opening degree is adjusted so that the equation (1) and the equation (2) are satisfied at the same time, and P2 is determined.

When the flow rate Q of the ink increases, the pressure in the tank 20 (see FIG. 2) is constant, so that the increase in the flow rate Q increases the flow resistance between the tank 20 and the first pressure control mechanism 31. Therefore, the pressure P1 in the first pressure chamber 305 decreases by the increase in the flow resistance. Therefore, the force (P1 · Sv) that closes the valve 307 is reduced, and as is clear from the equation (1), the pressure P2 in the second pressure chamber 306 is instantaneously increased.

Further, the equation of R = (P1-P2) / Q is derived from the equation (2). As the flow rate Q and the pressure P2 increase and the pressure P1 decreases, the flow resistance R decreases. As the flow resistance R decreases, the valve opening degree increases due to the relationship shown in FIG. As the valve opening degree increases, the length of the urging member 301 decreases, so that the displacement x from its free length increases. Therefore, the acting force (k1 · x) of the urging member 301 becomes large, and as is clear from the equation (1), the pressure P2 in the second pressure chamber 306 is instantaneously reduced.

On the other hand, when the flow rate Q of the ink flowing into the first pressure control mechanism 31 decreases, the first pressure control mechanism 31 operates in the opposite direction to the case where the flow rate Q increases. That is, an increase in the pressure P1 in the first pressure chamber 305 momentarily decreases the pressure P2 in the second pressure chamber 306, and the decrease in the pressure P2 reduces the flow resistance R, resulting in a second. The pressure P2 in the pressure chamber 306 increases instantaneously.

In this way, the momentary increase and decrease of the pressure P2 are repeated, the valve opening degree changes according to the flow rate Q, and as a result of both equations (1) and (2) being compatible, the inside of the second pressure chamber 306 The pressure P2 is controlled to be constant. Therefore, the pressure on the downstream side (common supply flow path 12 side) of the first pressure control mechanism 31 is autonomously and constantly controlled.

Further, the negative pressure adjusting member 311 fixed to the body 310 is for changing the storage length and the urging force of the urging member 301A in the first pressure chamber 305. A protrusion is provided at the position of the negative pressure adjusting member 311 facing the first pressure chamber 305. By selectively fixing the negative pressure adjusting member 311 having a different height of the protrusion to the body 310, the urging force of the urging member 301A is changed, and the control pressure of the first pressure control mechanism 31 is changed or adjusted. be able to. Therefore, even when the head difference between the negative pressure control unit 3 and the formation surface of the discharge port of the recording head 1 is different, the negative pressure adjusting member 311 can be replaced with one having a different protrusion height. It can be handled by the same first pressure control mechanism 31.

9-2. Second pressure control mechanism The second pressure control mechanism 32 as the back pressure type regulator mechanism is configured in the same manner as the first pressure control mechanism 31 described above except for the following differences, and thus is the first pressure control mechanism. The same parts as those in 31 are designated by the same reference numerals and the description thereof will be omitted.

One of the differences is that the valve 307 of the second pressure control mechanism 32 is arranged in the second pressure chamber 306. Another difference is between the valve 307 and the orifice 308 when the pressure receiving plate 302 of the second pressure control mechanism 32 moves in the urging direction of the urging member 301B (downward in FIG. 13B). The gap (valve opening) is widened. Yet another difference is that the second pressure chamber 306 of the second pressure control mechanism 32 communicates with the ink inlet 313A (see FIG. 13A), and the first pressure chamber 305 of the second pressure control mechanism 32 communicates with the ink inlet 313A (see FIG. 13A). It communicates with the ink outlet 313B (see FIG. 13A). Therefore, in the second pressure control mechanism 32, the ink flows from the second pressure chamber 306 toward the first pressure chamber 305, contrary to the first pressure control mechanism 31. Yet another difference is that the valve 307 of the second pressure control mechanism 32 is integrated with the pressure receiving plate 302 via the shaft 304. Further, the shaft 304 of the second pressure control mechanism 32 penetrates the orifice 308 and abuts on the shaft holder 309. Since the valve 307 and the pressure receiving plate 302 are integrated via the shaft 304, not only the urging force of the urging member 301A in the first pressure chamber 305 but also the urging member 301B in the second pressure chamber 306 Also receive urgency.

The mechanism of pressure adjustment in the second pressure control mechanism 32 is the same as that of the first pressure control mechanism 31 described above, and the pressure P1 in the second pressure chamber 306 on the upstream side indicates the balance of the forces applied to each part as described below. It is determined by the relational expression (3).
P1 = _P0- (P2 ・ Sv + k1 ・ x) / Sd ・ ・ ・ (3)

Sd is the pressure receiving area of the pressure receiving plate 302, Sv is the pressure receiving area of the valve 307, P0 is the atmospheric pressure, P1 is the pressure in the second pressure chamber 306 on the upstream side, and P2 is the first pressure chamber 305 on the downstream side. Is the pressure inside. k1 is the spring constant of the urging member 301 (301A, 301B), and x is the displacement (spring displacement) of the urging member 301 (301A, 301B). Since the second term on the right side of the equation (3) is always a positive value, P1 <P0 and P1 is a negative pressure. Further, the relationship of the following equation (4) is established between the ink flow resistance R in the gap between the valve 307 and the orifice 308 and the flow rate Q of the ink passing through the orifice 308.
P1 = P2-QR ... (4)

The gap (valve opening) between the valve 307 and the orifice 308 and the flow resistance R are set as shown in FIG. 13, that is, the flow resistance R decreases as the valve opening increases. .. By adjusting the valve opening degree so that the equation (3) and the equation (4) are satisfied at the same time, the pressure P1 in the second pressure chamber 306 on the upstream side is determined.

When the flow rate Q of the ink increases, the pressure of the suction pump 1000 (see FIG. 3) connected to the downstream side of the negative pressure control unit 3 is constant. The flow resistance up to the suction pump 1000 increases. Therefore, the pressure P2 in the first pressure chamber 305 rises by the increase in the flow resistance. Therefore, the force (P2 · Sv) that closes the valve 307 increases, and as is clear from the equation (3), the pressure P1 in the second pressure chamber 306 on the upstream side momentarily decreases.

Further, the equation of R = (P1-P2) / Q is derived from the equation (4). As the flow rate Q and the pressure P2 increase and the pressure P1 decreases, the flow resistance R decreases. As the flow resistance R decreases, the valve opening degree increases due to the relationship shown in FIG. Since the length of the urging member 301 increases as the valve opening degree increases, the displacement x from its free length decreases. Therefore, the acting force (k1 · x) of the urging member 301 becomes small, and as is clear from the equation (3), the pressure P1 in the second pressure chamber 306 on the upstream side increases instantaneously.

On the other hand, when the flow rate Q of the ink decreases, the second pressure control mechanism 32 operates in the opposite direction to the case where the flow rate Q increases. That is, when the pressure P2 in the first pressure chamber 305 on the downstream side drops, the pressure P1 in the second pressure chamber 306 on the upstream side increases instantaneously, and the flow resistance R increases due to the increase in the pressure P1. As a result, the pressure P1 in the second pressure chamber 306 on the downstream side is instantaneously reduced.

In this way, the instantaneous increase and decrease of the pressure P1 in the second pressure chamber 306 on the upstream side are repeated, the valve opening changes according to the flow rate Q, and the equations (3) and (4) are compatible. As a result, the pressure P1 in the second pressure chamber 306 on the upstream side is controlled to be constant. Therefore, the pressure on the upstream side (common recovery flow path 13 side) of the second pressure control mechanism 32 is autonomously and constantly controlled.

Further, the storage length and the urging force of the urging member 301A in the first pressure chamber 306 are determined by the negative pressure adjusting member 311 of the second pressure control mechanism 32, similarly to the negative pressure adjusting member 311 in the first pressure control mechanism 31. Can be changed. Therefore, the same negative pressure control unit 3 can be diverted to various recording devices having different usage conditions to reduce the cost.

(Second embodiment)
FIG. 15 is an explanatory diagram of a second embodiment of the present invention, and the same parts as those of the first embodiment described above are designated by the same reference numerals and the description thereof will be omitted.

In the present embodiment, the first tank 321 and the second tank 322 capable of accommodating ink are connected to the ink supply unit 220 and the negative pressure control unit 3 similar to the first embodiment through the switching mechanism 4. There is. The first tank 321 is connected to the main tank 1002 through the filter 1005, and ink can be replenished from the main tank 1002. The switching mechanism 4 includes four on-off valves 44 (44A, 44B, 44C, 44D), the first and second pressure control mechanisms 31 and 32 in the negative pressure control unit 3, and the first and second tanks. The connection relationship between 321 and 322 is switched. The on-off valves 44A and 44B are connected to the first tank 321 and the on-off valves 44C and 44D are connected to the second tank 322. Hereinafter, the on-off valves 44A and 44C connected to the upstream side of the first pressure control mechanism 31 are also referred to as a first switching unit, and the on-off valves 44B and 44D connected to the downstream side of the second pressure control mechanism 32 are second-switched. Also called a department.

FIG. 15A shows a state in which the on-off valves 44A and 44D are opened and the on-off valves 44B and 44C are closed, and the portion upstream of the first pressure control mechanism 31 is on the second tank 322 side. The second pressure control mechanism 32 is connected to the first tank 321 side. On the contrary, FIG. 15B shows a state in which the on-off valves 44A and 44D are closed and the on-off valves 44B and 44C are opened, and the first pressure control mechanism 31 is connected to the first tank 321 side. The second pressure control mechanism 32 is connected to the second tank 322 side. As described above, the first and second pressure control mechanisms 31 and 32 and the first and second tanks 321, by the first switching unit (switching valves 44A and 44C) and the second switching section (switching valves 44B and 44D) are used. The connection relationship between 322 and 322 can be switched between each other. This makes it possible to switch the ink flow direction with respect to the first and second tanks 321 and 322. For example, when a pigment ink containing a large amount of solid components is used, the sedimentation of the pigment components in the tank can be suppressed by switching the flow direction of the ink, and a stable recording operation can be performed.

The switching control of the switching mechanism 4 is performed by the control unit on the recording device main body side based on the signal from the detection mechanism (not shown) that detects the remaining amount of ink in the first and second tanks 321 and 322. The switching mechanism 4 may have a function of switching the connection state as described above. Therefore, the switching mechanism 4 is not limited to a form in which four on-off valves are simply combined as in this example, and for example, a three-way valve, a slide valve, a rotary valve, or the like is used to use a first and second switching unit. It may be a form constituting.

Further, the negative pressure compensation mechanism 37 is also provided in this embodiment. Therefore, as in the first embodiment described above, even when a large amount of ink is ejected from the ejection port 113 of the element substrate 10 in a short time, the negative pressure of the common recovery flow path 13 is suppressed from dropping too much. , Stable recording operation can be performed. Further, since the bypass valve 35 is deployed, the strong recovery mode (strong circulation recovery) can be implemented.

(Third embodiment)
FIG. 16 is an explanatory diagram of a third embodiment of the present invention, and the same parts as those of the above-mentioned second embodiment are designated by the same reference numerals and the description thereof will be omitted. The main difference from the second embodiment is that the pressurizing pump 1003 and the suction pump 1000 are used to generate ink flow without using the second pressure adjusting mechanism in the second embodiment.

FIG. 16A shows a state in which the on-off valves 44A and 44D are opened and the on-off valves 44B and 44C are closed. In this state, the pressurizing pump 1003 pumps out the ink in the second tank 322, and the suction pump 1000 sends the ink to the first tank 321 side. On the contrary, FIG. 16B shows a state in which the on-off valves 44A and 44D are closed and the on-off valves 44B and 44C are opened. In this state, the pressurizing pump 1003 pumps out the ink in the first tank 321 and the suction pump 1000 sends the ink to the second tank 322 side. Therefore, when the flow direction of the ink is switched as in the second embodiment and, for example, a pigment ink containing a large amount of solid components is used, sedimentation of the pigment components inside the tank is suppressed and a stable recording operation is performed. Can be carried out. The effects of the negative pressure compensating mechanism 37 and the bypass valve 35 are the same as in the first and second embodiments.

(Fourth Embodiment)
FIG. 17 is an explanatory diagram of a fourth embodiment of the present invention, and the same parts as those of the first and second embodiments described above are designated by the same reference numerals and the description thereof will be omitted. In the present embodiment, the switching mechanism 4 in the second embodiment is provided between the ink supply unit 220 and the ink ejection unit 300 in the first embodiment. In the switching mechanism 4, the on-off valves 44A and 44B are connected to the downstream side of the first pressure control mechanism 31, and the on-off valves 44C and 44D are connected to the upstream side of the second pressure control mechanism 32.

FIG. 17A shows a state in which the on-off valves 44A and 44D are opened and the on-off valves 44B and 44C are closed, the first pressure control mechanism 31 is connected to the common supply flow path 12, and the second pressure is reached. The control mechanism 32 is connected to the common recovery flow path 13. On the contrary, FIG. 17B shows a state in which the on-off valves 44A and 44D are closed and the on-off valves 44B and 44C are opened, and the first pressure control mechanism 31 is connected to the common recovery flow path 13. The second pressure control mechanism 32 is connected to the common supply flow path 12. By opening and closing the on-off valve 44 (44A, 44B, 44C, 44D) in this way, the connection relationship between the first and second pressure control mechanisms 31 and 32 and the common supply flow path 12 and the common recovery flow path 13 is switched. be able to. This makes it possible to switch the ink flow direction in the ink ejection unit 300 including the element substrate 10.

In this way, since the ink flow direction can be reversed in the ink ejection unit 300, foreign matter such as bubbles on the common supply flow path 12 side can also be ejected in the above-mentioned strong recovery mode. Generally, the flow path in the vicinity of the discharge port 113 is the finest flow path in the recording head 1. Therefore, it is difficult for foreign matter such as bubbles accumulated on the upstream side of the ejection port 113 to be discharged from the downstream side of the ejection port 113 beyond the ejection port even if the flow rate of the ink is increased. In the first to third embodiments described above, since the ink flow direction in the recording head 1 is limited to one direction, foreign matter such as bubbles on the common supply flow path 12 side is transferred to the common recovery flow path 13 side. It is difficult to discharge. In order to remove such foreign matter, a recovery method such as a suction recovery process of sucking ink from the ejection port is required, and depending on such a recovery method, waste ink that is not used for image recording is generated.

In the present embodiment, after the strong recovery mode is executed for a predetermined time, the ink flow direction in the recording head 1 is reversed by the switching mechanism 4, and then the strong recovery mode is executed again in the recording head 1. Foreign matter such as bubbles can be discharged to the tank 20. As a result, it is possible to carry out a more reliable recording operation while significantly reducing the amount of waste ink. Further, since the negative pressure compensation mechanism 37 is provided as in the first embodiment, even when a large amount of ink is ejected from the ejection port 113 of the element substrate 10 in a short time, the common recovery flow path 13 It is possible to suppress the negative pressure from dropping too much and perform stable recording operation.

(Fifth Embodiment)
FIG. 18 is an explanatory diagram of a fifth embodiment of the present invention, and the same parts as those of the first embodiment described above are designated by the same reference numerals and the description thereof will be omitted.

18 (a) and 18 (b) are schematic views of an ink flow path (single color) in the recording apparatus of this embodiment. The major differences from the first embodiment are that there is no second pressure control mechanism (L) 32, and that the downstream side of the pump 1000 is not the main tank 20 but the downstream side of the first pressure control mechanism (H) 31. It is a point connected to. Further, a three-way valve 45 is provided between the first pressure control mechanism 31 and the ink ejection unit 300, and a three-way valve 46 is provided between the ink ejection unit 300 and the pump 1000. The three-way valve 45 is configured to switch the connection destination on the downstream side of the first pressure control mechanism 31 to either the common supply flow path 12 or the common recovery flow path 13. The three-way valve 46 is configured to switch the connection destination on the upstream side of the pump 1000 to either the common supply flow path 12 or the common recovery flow path 13.

FIG. 18A shows a state in which the ink in the recording element substrate 10 circulates so as to flow from the common supply flow path 12 toward the common recovery flow path 13. The flow path states in the three-way valves 45 and 46 are cut off as shown by the lines in the circles in the figure representing them. By driving the pump 1000, the ink flows from the three-way valve 45 to the common supply flow path 12, the recording element substrate 10, the common recovery flow path 13, and the three-way valve 46, and then enters the pump 1000 again. Circulate. In the recording operation, ink is ejected from the nozzle of the recording element substrate 10, and the reduced amount of ink is replenished from the main tank 20 through the pressurizing pump 1003, the filter 1001, and the first pressure control mechanism 31. The ink pressure on the upstream side of the ink ejection unit 300 is controlled by the first pressure control mechanism 31 to a negative pressure appropriate for the ink ejection operation. Here, it is assumed that only the ink of a specific color is used for recording in the monochrome mode or the like, and the ink ejection operation in the ink flow of FIG. 18A cannot be performed. In this case, the pressure on the downstream side of the pump 1000 is maintained at a predetermined pressure by the first pressure control mechanism 31 even when only the ink is circulated by the pump 1000.

Further, a passive valve 33 capable of compensating for negative pressure is provided as in the first embodiment. Therefore, even when a large amount of ink is ejected from the ejection port 113 of the recording element substrate 10 in a short time, the negative pressure of the common recovery flow path 13 is suppressed from dropping too much, and stable recording operation is performed. be able to.

FIG. 18B shows a state in which the ink is circulated so that the ink in the recording element substrate 10 flows from the common supply flow path 12 toward the common recovery flow path 13 by switching the three-way valves 45 and 46. show. The flow path states in the three-way valves 45 and 46 are cut off as shown by the lines in the circles in the figure representing them.

In this way, since the ink flow direction can be reversed in the ink ejection unit 300, bubbles and foreign matter on the common supply flow path 12 side can be ejected. Further, in the present embodiment, only one ink supply path is required for one color of ink from the main tank 20, and since there is no second pressure control mechanism, the configuration of the recording device can be simplified and downsized. can.

(Sixth Embodiment)
FIG. 19 is an explanatory diagram of a sixth embodiment of the present invention, and the same parts as those of the fifth embodiment described above are designated by the same reference numerals and the description thereof will be omitted.

19 (a) and 19 (b) are schematic views of an ink flow path (single color) in the recording apparatus of this embodiment. The difference from the fifth embodiment is that a three-way valve 47 is added on the downstream side of the passive valve 33 that provides the negative pressure compensation function. The three-way valve 47 is configured to switch the connection destination on the downstream side to the upstream side of the common supply flow path 12 or the upstream end of the common recovery flow path 13.

FIG. 19A shows a state in which the ink in the recording element substrate 10 circulates so as to flow from the common supply flow path 12 toward the common recovery flow path 13. At that time, the flow path state in the three-way valve 47 is switched as shown by the line in the circle in the figure represented by them, and the downstream side thereof is connected to the upstream end side of the common recovery flow path 13. There is. When high-duty recording is performed in this state, ink is also supplied into the recording element substrate 10 from the common recovery flow path 13 side. At that time, the passive valve 33 is opened and ink is supplied from the upstream side of the common recovery flow path 13, so that the negative pressure in the common recovery flow path 13 is suppressed so as not to rise excessively. Similarly, in FIG. 18A of the fifth embodiment described above, the negative pressure compensation function is activated by the passive valve 33 at the time of high duty recording, but the ink is supplied from the downstream side of the common recovery flow path 13. Therefore, there is a possibility that transient pressure fluctuations may occur due to the influence of inertia generated by the reversal of the ink flow when the recording duty changes suddenly. In particular, a long line head having a large ink flow rate has a large effect. On the other hand, in the sixth embodiment, since the ink is always supplied from the upstream side of the common recovery flow path 13, stable pressure can be ensured during any recording operation.

In FIG. 19B, by switching the three-way valves 45 and 46, the ink is circulated so that the ink in the recording element substrate 10 flows from the common supply flow path 12 toward the common recovery flow path 13. The state in which bubbles and foreign matters are discharged on the common supply flow path 12 side is shown. At that time, the three-way valve 47 is switched so that its downstream side is connected to the upstream side of the common supply flow path 12. The flow path state in the three-way valve 47 is switched as shown by the line in the circle in the figure representing it. In such a state, when high-duty recording is performed, ink is supplied from the upstream side of the common supply flow path 12 by opening the passive valve 33. Therefore, as in the case of FIG. 19A, the ink is supplied. Stable pressure can be secured.

(Other embodiments)
The recording head 1 may be able to eject the ink in the pressure chamber 123 from the ejection port 113 by using an ejection energy generating element such as a heater 115. Therefore, the recording head 1 is not limited to the configuration including the ink ejection unit 300, the ink supply unit 220, and the ink circulation unit 400 as shown in FIG. For example, the recording head 1 may constitute an ink ejection module (liquid ejection module) including at least a part of an ink ejection unit 300, an ink supply unit 220, and an ink circulation unit 400. Further, the method of the recording device is not limited to the full-line method as in the above-described embodiment, and the image is recorded by repeating the movement of the recording head in the main scanning direction and the transfer of the recording medium in the sub-scanning direction. , So-called serial scan method may be used.

The present invention can be widely applied to a liquid supply device that supplies various liquids and a liquid discharge device that can discharge various liquids. The present invention also relates to an inkjet device that performs various processes (recording, processing, coating, irradiation, reading, inspection, etc.) on various media (sheets) using an inkjet head capable of ejecting a liquid. Is also applicable. The medium (including a recording medium) includes various media such as paper, plastic, film, textile, metal, flexible substrate, etc., to which a liquid containing ink is applied, regardless of the material.

1 Recording head (liquid discharge head)
3 Negative pressure control unit (pressure control unit)
12 Common supply flow path 13 Common recovery flow path 33 Passive valve 34 On-off valve 37 Negative pressure compensation mechanism (pressure compensation unit)
113 Discharge port 123 Pressure chamber

Claims (13)

A liquid supply device that supplies liquid to a liquid discharge head that can discharge liquid in a pressure chamber from a discharge port.
The liquid supply flow path communicating with the pressure chamber and
The liquid recovery flow path communicating with the pressure chamber and
A first pressure control unit that controls the pressure in the supply flow path to a first pressure and a second pressure control unit that controls the pressure in the recovery flow path to a second pressure lower than the first pressure are included. A pressure difference is generated between the inside of the supply flow path and the inside of the recovery flow path so that the liquid is supplied from the supply flow path to the pressure chamber and the liquid in the pressure chamber is recovered from the recovery flow path. Pressure control means and
When the pressure in the recovery flow path is equal to or lower than a predetermined pressure, a pressure compensating means for supplying a liquid from the recovery flow path to the pressure chamber to compensate for a decrease in pressure in the recovery flow path.
A liquid supply device including a suction pump arranged at a position downstream of the second pressure control unit in a liquid recovery direction by the recovery flow path. Between the position on the upstream side of the recovery flow path in the liquid recovery direction from the second pressure control unit and the position on the downstream side of the recovery flow path in the recovery direction from the second pressure control unit. The liquid supply device according to claim 1, further comprising a bypass flow path. The liquid supply device according to claim 2, wherein the bypass flow path is provided with a bypass valve capable of opening / closing control. The first tank and the second tank that can store liquids,
The first position on the upstream side in the liquid supply direction from the first pressure control unit of the supply flow path is connected to the first tank, and the liquid is recovered from the second pressure control unit of the recovery flow path. The first form in which the second position on the downstream side in the direction is connected to the second tank, and the second form in which the first position is connected to the second tank and the second position is connected to the first tank. And the switching means that can be switched,
The liquid supply device according to any one of claims 1 to 3, wherein the liquid supply device comprises. The third position on the downstream side in the liquid supply direction from the first pressure control unit of the supply flow path is connected to one side of the pressure chamber, and the liquid is more liquid than the second pressure control unit of the recovery flow path. The first form in which the fourth position on the upstream side in the recovery direction is connected to the other side of the pressure chamber, and the third position is connected to the other side of the pressure chamber and the fourth position is connected to the other side of the pressure chamber. The liquid supply device according to any one of claims 1 to 4, further comprising a switching means capable of switching between the second form connected to one side and the second mode. A liquid supply device that supplies liquid to a liquid discharge head that can discharge liquid in a pressure chamber from a discharge port.
The liquid supply flow path communicating with the pressure chamber and
The liquid recovery flow path communicating with the pressure chamber and
A pressure difference is generated between the supply flow path and the recovery flow path so that the liquid is supplied from the supply flow path to the pressure chamber and the liquid in the pressure chamber is recovered from the recovery flow path. Pressure control means to make
When the pressure in the recovery flow path is equal to or lower than a predetermined pressure, a pressure compensating means for supplying a liquid from the recovery flow path to the pressure chamber to compensate for a decrease in pressure in the recovery flow path.
Equipped with
The pressure control means includes a first pressure control unit provided on the upstream side of the liquid supply direction by the supply flow path and controlling the pressure in the supply flow path, and an inlet is a liquid recovery direction by the recovery flow path. A liquid supply device comprising: a pump which is connected to the downstream side of the liquid and whose outlet is connected to a downstream side in a liquid supply direction by the supply flow path from the pressure control means. A liquid supply device that supplies liquid to a liquid discharge head that can discharge liquid in a pressure chamber from a discharge port.
The liquid supply flow path communicating with the pressure chamber and
The liquid recovery flow path communicating with the pressure chamber and
A pressure difference is generated between the supply flow path and the recovery flow path so that the liquid is supplied from the supply flow path to the pressure chamber and the liquid in the pressure chamber is recovered from the recovery flow path. Pressure control means to make
When the pressure in the recovery flow path is equal to or lower than a predetermined pressure, a pressure compensating means for supplying a liquid from the recovery flow path to the pressure chamber to compensate for a decrease in pressure in the recovery flow path.
The first mode in which the high pressure side of the pressure difference generated by the pressure control means is connected to the supply flow path and the low pressure side is connected to the recovery flow path, and the high pressure side is connected to the recovery flow path and said. A liquid supply device comprising a second mode in which the low pressure side is connected to the supply flow path and a switching means capable of switching between the second mode. In the first form, the pressure compensating means connects the high pressure side of the pressure difference generated by the pressure control means and the recovery flow path via a passive valve, and in the second form, the pressure compensating means is connected to the high pressure side. A switching means for switching the communication passage so as to connect the supply flow path via the passive valve is provided.
In the first form, the passive valve opens when the pressure in the recovery flow path is equal to or lower than a predetermined pressure, and in the second form, the passive valve opens when the pressure in the supply flow path is equal to or lower than the predetermined pressure. 7. The liquid supply device according to claim 7. The liquid supply device according to any one of claims 1 to 8, wherein the supply flow path and the recovery flow path communicate with each of the plurality of pressure chambers. The pressure compensating means according to any one of claims 1 to 9, wherein the pressure compensating means includes a communication passage for communicating the supply flow path and the recovery flow path when the pressure in the recovery flow path is equal to or lower than a predetermined pressure. The liquid supply device according to item 1. The liquid according to claim 10, wherein the pressure compensating means includes a passive valve that opens and closes the communication passage according to a differential pressure between the pressure in the supply flow path and the pressure in the recovery flow path. Feeding device. The liquid supply device according to claim 10 or 11, wherein the communication passage is provided with an on-off valve that can be controlled to open and close. A liquid discharge head including a pressure chamber, a discharge port communicating with the pressure chamber, and a discharge energy generating element for generating discharge energy for discharging the liquid in the pressure chamber from the discharge port.
The liquid supply device according to any one of claims 1 to 12.
A liquid discharge device characterized by being provided with.

Images