Recording head and inkjet recording device equipped therewith

Abstract

The present invention provides a recording head and an inkjet recording device equipped therewith that can suppress ink ejection failures caused by air bubbles in the ink being sent to the ejection nozzle with a simple configuration. [Solution] The recording head has an ink ejection section in which a plurality of ejection nozzles for ejecting ink are formed, and an ink reservoir connected to the ink ejection section. The ink reservoir has an internal flow path in the head connected to a common flow path through which ink flows, a bubble separation section for separating air bubbles contained in the ink flowing through the internal flow path in the head, a valve member for opening and closing a bubble outlet formed at the upper part of the bubble separation section, and an ink discharge flow path extending downward from an ink inlet formed at the lower end of the bubble separation section and connected to the ejection nozzles of the ink ejection section. The internal flow path in the head is connected to the ink discharge flow path substantially horizontally, and the confluence of the internal flow path in the head and the ink discharge flow path is located below the ink inlet.

Description

Technical Field

[0001] The present invention relates to a recording head mounted on an inkjet recording apparatus and an inkjet recording apparatus including the same.

Background Art

[0002] Conventionally, in an inkjet recording apparatus such as an inkjet printer, ink is ejected from ejection nozzles provided in a recording head, and the ejected ink adheres to a recording medium such as paper to form dots. The ink is sent out from an ink container, a predetermined amount is stored in a sub-tank, and the ink is supplied from the sub-tank to the recording head.

[0003] Patent Document 1 discloses a flow path member having a first surface and a second surface located on the opposite side of the first surface, a pressurizing portion located on the first surface, a plurality of ejection holes located on the second surface, a flexible substrate having one end located on the pressurizing portion and electrically connected to the pressurizing portion, a cover member covering the one end, and a heater located on the cover member. A liquid ejection head is disclosed.

[0004] Patent Document 2 discloses an inkjet recording apparatus including an inkjet head that ejects ink, a plug provided in a tube that supplies ink, a socket provided in the inkjet head and having an insertion port at the upper end into which the plug is inserted downward, and a shutter member that surrounds the side of the socket and is biased downward.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] If air bubbles contained in the ink enter the fine channels near the ejection nozzle along with the ink, the bubbles may block the channels, potentially causing malfunctions such as poor ink ejection (loose pins). Therefore, a method has been adopted in which an air bubble separation section is provided in the ink channel of the recording head, separating the ink from the air bubbles in the air bubble separation section and then discharging the separated air bubbles.

[0007] With the method described above, there is a risk that the ink stored in the bubble separation section may be moved by the fast flow of ink. As a result, the separated bubbles may be carried by the ink flow to the ejection nozzle, leading to a problem where the ejection nozzle becomes clogged with bubbles, causing ink ejection failure (loose pins).

[0008] In view of the above problems, the present invention aims to provide a recording head and an inkjet recording device equipped therewith that can suppress ink ejection failures caused by air bubbles contained in the ink being sent to the ejection nozzle with a simple configuration. [Means for solving the problem]

[0009] To achieve the above objective, the first configuration of the present invention is a recording head mounted on an inkjet recording device for recording an image on a recording medium, comprising an ink ejection unit and an ink reservoir. The ink ejection unit has a plurality of ejection nozzles for ejecting ink. The ink reservoir is connected to the ink ejection unit. The ink reservoir has an internal flow path in the head connected to a common flow path through which ink flows, a bubble separation unit for separating air bubbles contained in the ink flowing through the internal flow path in the head, a valve member for opening and closing a bubble outlet formed at the upper part of the bubble separation unit, and an ink discharge flow path extending downward from an ink inlet formed at the lower end of the bubble separation unit and connected to the ejection nozzles of the ink ejection unit. The internal flow path in the head is connected substantially horizontally to the ink discharge flow path, and the confluence of the internal flow path in the head and the ink discharge flow path is located below the ink inlet. [Effects of the Invention]

[0010] According to the first configuration of the present invention, the bubble separation unit is positioned above and separated from the flow of ink passing through the print head channel and the ink discharge channel. Therefore, even if high-velocity ink flows through the print head channel and the ink discharge channel, no ink movement occurs above the bubble separation unit. As a result, there is no risk of bubbles accumulating above the bubble separation unit being pulled by the ink flow and sent to the discharge nozzle. Accordingly, ink discharge failures caused by bubbles clogging the discharge nozzle can be effectively suppressed. [Brief explanation of the drawing]

[0011] [Figure 1] Diagram illustrating the schematic configuration of printer 100 as an inkjet recording device according to one embodiment of the present invention. [Figure 2] Plan view of the recording unit 9 of printer 100 [Figure 3] Side view of recording heads 17a to 17c that constitute line heads 11Y to 11K of the recording unit 9. [Figure 4] Plan view of recording heads 17a-17c as seen from the ink ejection surface F side. [Figure 5] A schematic diagram showing the internal structure of the ink supply path 40a, cleaning fluid supply path 40b, and recording heads 17a-17c that constitute the line head 11Y of printer 100. [Figure 6] Side cross-sectional view of the recording head 17a as seen from the upstream side in the paper transport direction. [Figure 7] Partial cross-sectional view of the area around the bubble separation section 47 of the recording head 17a [Figure 8] This is a partial cross-sectional view of the area around the bubble separation section 47, showing how the valve member 50 is positioned in the open position to discharge bubbles from within the bubble separation section 47. [Modes for carrying out the invention]

[0012] [1. Configuration of the inkjet recording device] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is an explanatory diagram showing the schematic configuration of a printer 100 as an inkjet recording device according to one embodiment of the present invention. The printer 100 is equipped with a paper feed cassette 2, which is a paper storage section. The paper feed cassette 2 is located at the bottom inside the printer body 1. Paper P, which is an example of a recording medium, is stored inside the paper feed cassette 2.

[0013] A paper feed device 3 is located downstream of the paper feed cassette 2 in the paper transport direction, that is, above and to the right of the paper feed cassette 2 in Figure 1. This paper feed device 3 separates and feeds the paper P one sheet at a time towards the upper right of the paper feed cassette 2 in Figure 1.

[0014] The printer 100 is equipped with a first paper transport path 4a inside. The first paper transport path 4a is located to the upper right of the paper feed cassette 2, in the direction of paper feeding. Paper P fed from the paper feed cassette 2 is transported vertically upward along the side of the printer body 1 by the first paper transport path 4a.

[0015] In the paper transport direction, a pair of registration rollers 13 is provided at the downstream end of the first paper transport path 4a. Furthermore, the first transport unit 5 and the recording unit 9 are located immediately downstream of the pair of registration rollers 13 in the paper transport direction. Paper P fed from the paper cassette 2 travels through the first paper transport path 4a to reach the pair of registration rollers 13. The pair of registration rollers 13 corrects the diagonal feeding of the paper P and, in timing with the ink ejection operation performed by the recording unit 9, feeds the paper P toward the first transport unit 5 (particularly the first transport belt 8, which will be described later).

[0016] The paper P, fed to the first transport unit 5 by the registration roller pair 13, is transported by the first transport belt 8 to a position opposite the recording unit 9 (particularly the recording heads 17a to 17c, which will be described later). An image is recorded on the paper P by the ejection of ink from the recording unit 9 onto the paper P. At this time, the ejection of ink from the recording unit 9 is controlled by the control device 110 inside the printer 100.

[0017] In the paper conveyance direction, a second conveyance unit 12 is arranged on the downstream side (the left side in FIG. 1) of the first conveyance unit 5. The paper P on which an image has been recorded by the recording unit 9 is sent to the second conveyance unit 12. The ink ejected onto the surface of the paper P is dried while passing through the second conveyance unit 12.

[0018] In the paper conveyance direction, a decurler unit 14 is provided on the downstream side of the second conveyance unit 12 and near the left side surface of the printer main body 1. The paper P on which the ink has been dried by the second conveyance unit 12 is sent to the decurler unit 14, and the curl generated in the paper P is corrected.

[0019] In the paper conveyance direction, a second paper conveyance path 4b is provided on the downstream side (above in FIG. 1) of the decurler unit 14. When double-sided printing is not performed, the paper P that has passed through the decurler unit 14 passes through the second paper conveyance path 4b and is discharged to a paper discharge tray 15a provided outside the left side surface of the printer 100. Below the paper discharge tray 15a, a sub-discharge tray 15b for discharging unnecessary paper P (waste paper) on which printing defects or the like have occurred is provided.

[0020] Above the recording unit 9 and the second conveyance unit 12 at the upper part of the printer main body 1, a reverse conveyance path 16 for performing double-sided printing is provided. When double-sided printing is performed, the paper P that has completed recording on one side (the first side) and has passed through the second conveyance unit 12 and the decurler unit 14 is sent to the reverse conveyance path 16 through the second paper conveyance path 4b.

[0021] The paper P, sent to the reversal transport path 16, has its transport direction switched to record on the other side (second side) of the paper P. The paper P then passes over the top of the printer body 1 and is sent to the right, passing through the registration roller pair 13, and is sent back to the first transport unit 5 with the second side facing upwards. In the first transport unit 5, the paper P is transported to a position opposite the recording unit 9, and an image is recorded on the second side by ink ejection from the recording unit 9. After double-sided recording, the paper P passes through the second transport unit 12, the decurler unit 14, and the second paper transport path 4b in order and is discharged into the paper output tray 15a.

[0022] Furthermore, a maintenance unit 19 and a cap unit 20 are positioned below the second transport unit 12. The maintenance unit 19 moves horizontally below the recording unit 9 when purging is performed, wipes off the ink ejected from the ink outlet of the recording head, and recovers the wiped-off ink. Purging refers to the operation of forcibly pushing ink out from the ink outlet of the recording head in order to discharge thickened ink, foreign matter, and air bubbles from inside the ink outlet. The cap unit 20 moves horizontally below the recording unit 9 when capping the ink ejection surface of the recording head, and then moves upward to be attached to the bottom surface of the recording head.

[0023] Figure 2 is a plan view of the recording unit 9. The recording unit 9 comprises a head housing 10 and line heads 11Y, 11M, 11C, and 11K. The line heads 11Y to 11K are held in the head housing 10 at a height that forms a predetermined gap (e.g., 1 mm) with respect to the conveying surface of an endless first conveyor belt 8 stretched over a plurality of rollers, including a drive roller 6a, a driven roller 6b, and a tension roller (not shown). The drive roller 6a causes the first conveyor belt 8 to travel in the direction of conveying the paper P (direction of arrow A).

[0024] Each line head 11Y to 11K has multiple (in this case, three) recording heads 17a to 17c. The recording heads 17a to 17c are arranged in a staggered pattern along the paper width direction (arrow BB' direction) perpendicular to the paper transport direction (arrow A direction). Each recording head 17a to 17c has multiple ink nozzles 18. Each ink nozzle 18 is arranged at equal intervals in the width direction of the recording head, that is, in the paper width direction (arrow BB' direction). From the line heads 11Y to 11K, yellow (Y), magenta (M), cyan (C), and black (K) inks are ejected towards the paper P being transported by the first transport belt 8 via the ink nozzles 18 of the recording heads 17a to 17c.

[0025] Figure 3 is a side view of the recording heads 17a to 17c that constitute the line heads 11Y to 11K of the recording unit 9, and Figure 4 is a plan view of the recording heads 17a to 17c viewed from the ink ejection surface F1 side. Note that the recording heads 17a to 17c have the same shape and configuration, so they are shown in a single figure in Figures 3 and 4. As shown in Figures 3 and 4, the ink ejection surface (nozzle surface) F1 of the recording heads 17a to 17c is provided with multiple nozzle regions Ra to Rd (four blocks in this case) in which numerous ink ejection ports 18 (see Figure 2) are arranged. The ink ejection surface F1 is formed of, for example, SUS (stainless steel).

[0026] Each of the recording heads 17a to 17c, which make up each line head 11C to 11K, is supplied with four colors (cyan, magenta, yellow, and black) of ink from the liquid supply mechanism 70 (see Figure 5), according to the color of each line head 11C to 11K.

[0027] Each recording head 17a to 17c, in response to a control signal from the control device 110 (see Figure 1), ejects ink from its ink ejection port 18 toward the paper P being transported by being held and adsorbed onto the transport surface of the first transport belt 8, according to the image data received from an external computer. As a result, a color image is formed on the paper P on the first transport belt 8 by superimposing four colors of ink: cyan, magenta, yellow, and black. In addition, a cleaning fluid supply unit 30 for supplying cleaning fluid is provided at one end of the recording heads 17a to 17c in the longitudinal direction (arrow BB' direction), which is perpendicular to the paper transport direction (arrow A direction). The cleaning fluid supply unit 30 has a number of cleaning fluid supply ports 30a.

[0028] In printer 100, in order to clean the ink ejection surface F1 of the recording heads 17a to 17c, when starting printing after a long period of inactivity and between printing operations, ink is ejected (purged) from the ink ejection ports 18 of all recording heads 17a to 17c, and cleaning fluid is supplied from the cleaning fluid supply port 30a to the cleaning fluid supply surface F2. A wiper (not shown) then wipes the ink ejected onto the ink ejection surface F1 along with the cleaning fluid, performing a recovery operation of the recording heads 17a to 17c to prepare for the next printing operation. The ink and cleaning fluid wiped from the ink ejection surface F1 are collected by an ink receiving unit (not shown).

[0029] [2. Flow path configuration including recording head] Figure 5 is a schematic diagram showing the internal structure of the ink supply path 40a, the cleaning fluid supply path 40b, and the recording heads 17a to 17c that constitute the line head 11Y of the printer 100. Figure 6 is a side cross-sectional view of the recording head 17a viewed from the upstream side in the paper transport direction. Note that the line heads 11M to 11K have exactly the same configuration as line head 11Y, so their explanation is omitted. Also, since the internal structure of the recording heads 17a to 17c is identical, only the internal structure of recording head 17a is shown in Figures 5 and 6.

[0030] As shown in Figure 5, a common channel 40 through which ink and cleaning fluid pass is connected to the recording heads 17a to 17c. Within the common channel 40, two ink supply channels 40a through which ink passes and one cleaning fluid supply channel 40b through which cleaning fluid passes are formed. The upstream ends of the ink supply channels 40a and the cleaning fluid supply channel 40b are connected to a fluid supply mechanism 70. The fluid supply mechanism 70 consists of a tank for storing ink and cleaning fluid, and a pump (neither shown) for drawing ink and cleaning fluid from the tank.

[0031] The two ink supply paths 40a branch into six paths of three at the downstream end, and two of these are connected to the ink ejection ports 18 (see Figure 2) of the recording heads 17a to 17c. The cleaning fluid supply path 40b branches into three paths at the downstream end and is connected to the cleaning fluid supply section 30 (see Figures 3 and 4) of the recording heads 17a to 17c. The unit including the recording heads 17a to 17c and the common flow path 40 is called the head unit.

[0032] One of the two ink supply paths 40a is used to supply ink from the liquid supply mechanism 70 to the recording heads 17a to 17c, and the other is used to collect ink from the recording heads 17a to 17c and return it to the liquid supply mechanism 70. When recording images with a large ink output, both of the two ink supply paths 40a can also be used to supply ink to the recording heads 17a to 17c.

[0033] Each of the recording heads 17a to 17c can be individually attached to and detached from the common channel 40. More specifically, three joint mechanisms 45 connecting each of the recording heads 17a to 17c to two ink supply channels 40a and one cleaning fluid supply channel 40b are fastened from above the common channel 40 with fixing screws (not shown). Note that Figures 5 and 6 only show the two joint mechanisms 45 connected to the two ink supply channels 40a.

[0034] Each recording head 17a to 17c includes an ink ejection section 41, an ink reservoir 43, a heater 44, and a joint mechanism 45. The ink ejection section 41 is provided with an ink ejection surface F1 on which numerous ink ejection ports 18 are arranged, and a cleaning fluid supply section 30 for supplying cleaning fluid (see Figure 4 for both).

[0035] The ink reservoir 43 includes a head channel 46, a bubble separation section 47, and an ink discharge channel 48. The head channel 46, the bubble separation section 47, and the ink discharge channel 48 are each provided in pairs corresponding to two joint mechanisms 45.

[0036] A heater 44 is positioned between the ink ejection unit 41 and the ink reservoir 43. The heater 44 heats the ink flowing through the internal flow path 46 (the second flow path 46b described later) to a predetermined temperature as needed, and also heats the ink ejection unit 41 so that ink is smoothly ejected from the ink ejection port 18.

[0037] The head's internal flow path 46 has a first flow path 46a and a second flow path 46b. The first flow path 46a extends downward through the back of the head 43 from two joint mechanisms 45 and then bends inward in the width direction. The second flow path 46b is connected to the downstream end of the first flow path 46a at the center of the recording head 17a in the width direction and extends from the inside to the outside in the width direction within the ink reservoir 43. The second flow path 46b is located within the ink reservoir 43 adjacent to the heater 44.

[0038] The bubble separation unit 47 is located downstream of the second flow path 46b and temporarily stores the ink supplied from the ink reservoir 43 to the ink discharge unit 41 to separate the bubbles contained in the ink. The ink discharge flow path 48 is connected to the downstream end of the second flow path 46b and extends downward through the ink reservoir 43 toward the ink discharge unit 41.

[0039] The ink supplied from the ink supply passage 40a to the ink reservoir 43 via the joint mechanism 45 passes sequentially through the first passage 46a, the second passage 46b, the bubble separation section 47, and the ink discharge passage 48, before being sent to the ink discharge section 41 and discharged from the ink discharge port 18.

[0040] [3. Configuration of the bubble separation section around the incubator] The following describes the detailed configuration of the area around the bubble separation unit 47 of the recording head 17a, which is a characteristic feature of the present invention. Figure 7 is a partial cross-sectional view of the area around the bubble separation unit 47 of the recording head 17a. Here, the configuration of the area around the bubble separation unit 47 located on one side of the recording head 17a (left side in Figure 6) is shown as an example, but the configuration on the other side (right side in Figure 6) is the same. The configurations of the recording heads 17b and 17c are also the same.

[0041] As shown in Figure 7, the bubble separation unit 47 includes an ink inlet 47a and a bubble outlet 47b. The ink inlet 47a is formed at the lower end of the bubble separation unit 47. The bubble outlet 47b is formed at the upper end of the bubble separation unit 47. One end (upper end) of the ink discharge channel 48 is connected to the ink inlet 47a, and the other end (lower end) of the ink discharge channel 48 is connected to the ink ejection unit 41. A first O-ring 60a is fitted to the lower end of the ink discharge channel 48 to seal the gap between the ink discharge channel 48 and the ink ejection unit 41.

[0042] A valve member 50, which is movable in the vertical direction, is arranged inside the bubble separation section 47. The valve member 50 has a large diameter section 50a and a small diameter section 50b. The large diameter section 50a is located below the bubble outlet 47b, and the small diameter section 50b protrudes upward from the bubble outlet 47b. A spiral male screw (not shown) is formed on the outer circumferential surface of the large diameter section 50a, and a female screw (not shown) is formed on the inner circumferential surface of the bubble separation section 47.

[0043] By gripping the small-diameter portion 50b and rotating the valve member 50, the male thread formed on the large-diameter portion 50a slides along the female thread formed on the bubble separation portion 47. As a result, the valve member 50 reciprocates up and down within the bubble separation portion 47, and is selectively positioned between a closed position (see Figure 7) that closes the bubble outlet 47b and an open position (see Figure 8) that opens the bubble outlet 47b.

[0044] A second O-ring 60b is fitted at the boundary between the large-diameter portion 50a and the small-diameter portion 50b to seal the gap between the bubble outlet 50b and the valve member 50. By positioning the valve member 50 in the closed position, the second O-ring 60b is pressed against the periphery of the bubble outlet 47b, thereby closing the bubble outlet 47b.

[0045] A cover member 51 is attached to the upper end of the bubble separation section 47. The cover member 51 covers the bubble discharge section 47b and the small diameter section 50b of the valve member 50. A third O-ring 60c is attached to the periphery of the cover member 51 to seal the gap between the bubble separation section 47 and the cover member 51.

[0046] Figure 8 is a partial cross-sectional view of the area around the bubble separation section 47, showing how the valve member 50 is positioned in the open position to discharge bubbles from within the bubble separation section 47. Referring to Figures 7 and 8, a method for filling the recording heads 17a to 17c with ink at the time of shipment of the printer 100 will be explained.

[0047] When filling the recording head 17a with ink, as shown in Figure 8, the lid member 51 attached to the upper end of the bubble separation unit 47 is removed. Then, the valve member 50 is rotated in a predetermined direction to the open position. In this state, the liquid supply mechanism 70 (see Figure 5) is driven to supply ink to the recording head 17a via the ink supply passages 40a and 40b. The ink flows into the ink discharge passage 48 after passing through the joint mechanism 45, the first passage 46a, and the second passage 46b.

[0048] Here, the ink discharge section 41, which is connected to the lower end of the ink discharge channel 48, is provided with a mesh-like network of fine ink channels (not shown) leading to numerous ink outlets 18 (see Figure 2). Therefore, the flow resistance of the ink from the ink discharge channel 48 to the ink discharge section 41 is greater than the flow resistance of the ink heading towards the bubble separation section 47. Consequently, ink flowing into the ink discharge channel 48 is preferentially sent to the bubble separation section 47, and there is no risk of leakage from the ink outlets 18.

[0049] Air bubbles contained in the ink flowing into the bubble separation section 47 enter the bubble separation section 47 from the ink inlet 47a along with the ink. At this time, the valve member 50 is positioned in the open position, and a gap is formed between the second O-ring 60b and the bubble outlet 47b. Therefore, air bubbles that enter the bubble separation section 47 along with the ink pass through this gap and are discharged to the outside (indicated by the dashed arrow in Figure 8). By continuing to supply ink until the ink overflows to the outside from the bubble outlet 47b, the air bubbles present in the joint mechanism 45, the first flow path 46a, and the second flow path 46b can be completely discharged.

[0050] When ink overflows from the bubble outlet 50b, the liquid supply mechanism 70 is stopped, and the ink supply is halted. Then, the valve member 50 is rotated in the reverse direction to the closed position, and the ink filling of the recording head 17a is completed.

[0051] In this embodiment, the second channel 46b is not directly connected to the bubble separation section 47, but is connected to the bubble separation section 47 via the ink discharge channel 48. More specifically, the confluence 52 of the second channel 46b and the ink discharge channel 48 is located below the ink inlet 47a of the bubble separation section 47.

[0052] With the above configuration, the bubble separation unit 47 is positioned above the flow of ink passing through the second channel 46b and the ink discharge channel 48 (dashed arrow in Figure 7). Therefore, even if high-velocity ink flows through the second channel 46b and the ink discharge channel 48 during the purging operation that pushes ink out from the ink outlet 18, no ink movement occurs in the upper part of the bubble separation unit 47 (bubble accumulation area).

[0053] As a result, bubbles accumulating above the bubble separation section 47 are less likely to be pulled by the ink flow, and there is no risk of bubbles being sent to the ink outlet 18 via the ink discharge channel 48. Therefore, ink ejection failure (loose pins) caused by bubbles clogging the ink outlet 18 can be effectively suppressed.

[0054] In this embodiment, a sloping section 53 is formed in the second channel 46b connected to the ink discharge channel 48. The sloping section 53 is formed on the inner surface of the second channel 46b on the side closer to the bubble separation section 47 (upper side of Figure 7) immediately upstream of the confluence section 52 (right side of Figure 7). The sloping section 53 is inclined in a direction away from the bubble separation section 47 (downward direction of Figure 7) from the upstream side to the downstream side (right side to left side of Figure 7) with respect to the ink flow in the second channel 46b.

[0055] According to the above configuration, the ink flowing through the second channel 46b hits the inclined section 53 and changes direction along the inclined section 53 toward the ink discharge section 41 (downward). As a result, the ink that flows into the ink discharge channel 48 is less likely to flow toward the bubble separation section 47, and thus the movement of the ink in the bubble separation section 47 is further reduced.

[0056] Furthermore, in this embodiment, the inner diameter d1 of the ink inlet 47a formed in the bubble separation section 47 is smaller than the inner diameter d2 of the ink discharge channel 48. In other words, the cross-sectional area of ​​the channel from the ink discharge channel 48 toward the bubble separation section 47 is smaller than the cross-sectional area of ​​the channel from the ink discharge channel 48 toward the ink ejection section 41.

[0057] With the above configuration, by narrowing the cross-sectional area of ​​the flow path toward the bubble separation section 47, a difference in flow resistance can be generated between this flow path and the flow path toward the ink discharge section 41. As a result, it becomes more difficult for ink to flow into the bubble separation section 47, and ink movement in the bubble separation section 47 becomes even less likely.

[0058] Furthermore, a connecting portion 54 is formed between the ink inlet 47a and the ink discharge channel 48, which tapers in the opposite direction from the ink discharge channel 48 toward the ink inlet 47a. As a result, the cross-sectional area of ​​the channel from the ink discharge channel 48 toward the ink inlet 47a narrows continuously (smoothly), and no step is formed near the ink inlet 47a. Therefore, even if the ink heading toward the bubble separation section 47 contains air bubbles, the air bubbles can move smoothly to the top of the bubble separation section 47 without getting caught on any steps.

[0059] Furthermore, in the conventional configuration in which the second flow path 46b is connected to the bubble separation section 47, the in-head flow path 46, which is piped from above to below the ink reservoir 43, needs to be extended further upward, resulting in a complex flow path configuration. In contrast, in this embodiment, since the second flow path 46b merges with the ink discharge flow path 48 below the bubble separation section 47, the in-head flow path 46 can be made into a simple flow path configuration consisting only of the first flow path 46a and the second flow path 46b.

[0060] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. For example, although the above embodiment described a configuration in which three recording heads 17a to 17c are mounted on one head unit 51, the head unit 51 may also be configured to have only one recording head, or to have two or four or more recording heads.

[0061] Furthermore, although the above embodiment described an example using a color printer that records color images using four colors of ink as the inkjet recording device, it is also possible to use the recording head of this embodiment even when using a monochrome printer that records monochrome images using black ink. [Industrial applicability]

[0062] This invention is applicable to inkjet recording devices such as inkjet printers equipped with a recording head. [Explanation of symbols]

[0063] 17a~17c Recording head 18. Ink ejection port (ejection nozzle) 30 Cleaning fluid supply unit 40 Common channel 40a Ink supply path (liquid supply path) 40b Cleaning fluid supply path (fluid supply path) 41 Ink ejection section 43 Incidence reservoir 50 Liquid supply mechanism 51 Head Unit 45 Joint mechanism 46 Head internal flow path 46a First channel 46b Second channel 47. Bubble separation section 47a Ink Inlet 47b Air bubble outlet 48 Ink Ejection Channel 50 Valve member 50a Large diameter section 50b Small diameter section 51 Lid member 52 Confluence 53 Slope 54 Connecting part 100 Printers (Inkjet Recording Devices)

Claims

1. An ink ejection section in which multiple ejection nozzles for ejecting ink are formed, An ink reservoir connected to the aforementioned ink ejection unit, A recording head mounted on an inkjet recording device for recording images on a recording medium, The aforementioned ink reservoir is A head internal channel connected to the common channel through which the aforementioned ink flows, A bubble separation unit for separating air bubbles contained in the ink flowing through the internal flow path of the print head, A valve member that opens and closes a bubble discharge port formed at the upper part of the bubble separation section, An ink discharge channel extends downward from the ink inlet formed at the lower end of the bubble separation section and is connected to the discharge nozzle of the ink discharge section, It has, A recording head characterized in that the internal flow path of the head is connected substantially horizontally to the ink discharge flow path, and the confluence of the internal flow path of the head and the ink discharge flow path is located below the ink inlet.

2. The internal flow path of the head has an inclined portion formed on the inner surface on the side closest to the bubble separation section immediately upstream of the confluence section. The recording head according to claim 1, characterized in that the inclined portion is inclined in a direction away from the bubble separation portion from the upstream side to the downstream side with respect to the flow of ink in the flow path inside the head.

3. The recording head according to claim 1, characterized in that the inner diameter of the ink inlet is smaller than the inner diameter of the ink discharge channel.

4. The recording head according to claim 3, characterized in that a connecting portion is formed between the ink inlet and the ink discharge channel, having an inverse tapered shape from the ink discharge channel toward the ink inlet.

5. The internal flow path of the head is A first channel connected to the common channel and extending substantially horizontally from the outside to the inside within the reservoir, A second channel is connected to the downstream end of the first channel and extends substantially horizontally from the inside to the outside within the ink reservoir, and is connected to the ink discharge channel, A recording head according to claim 1, characterized by being composed of the above.

6. A recording head according to any one of claims 1 to 5, A liquid supply mechanism that supplies one or more liquids, including the ink, to the recording head via the common channel, An inkjet recording device equipped with [a specific feature].

Images