Liquid dispensing device

Abstract

To provide a liquid dispensing device that can suppress the temperature drop of humidified air supplied to a sealed space along the nozzle surface. [Solution] The image forming apparatus includes a cap portion 61 that seals the space along the nozzle surface 33A of the recording head 33, a path forming portion that forms an air movement path from an intake port 73A that opens above the water surface WA2 of the water WA1 stored in the tank 71, through a sealed space SP1 sealed by the cap portion 61, to an exhaust port 75A that opens below the water surface WA2, and a pump 76 that moves the air in the movement path in the movement direction D6, wherein the intake port 73A and the exhaust port 75A are positioned such that the intake port 73A faces a specific range AR1 on the water surface WA2 where the air discharged from the exhaust port 75A rises to the surface.

Description

Technical Field

[0001] The present invention relates to a liquid ejection device.

Background Art

[0002] A liquid ejection device such as an inkjet printer includes a discharge unit and a sealing unit. The discharge unit has a nozzle surface on which nozzles are formed, and ejects ink from the nozzles. The sealing unit seals a space along the nozzle surface.

[0003] Also, a liquid ejection device capable of supplying humidified air into a sealed space sealed by the sealing unit is known as a related art (see Patent Document 1). Specifically, the liquid ejection device according to the related art includes a tank, a heater, a path forming unit, and a pump. The tank stores water. The heater warms the water stored in the tank. The path forming unit forms an air movement path from a first opening that opens above the water surface of the water stored in the tank to a second opening that opens below the water surface via the sealed space. The pump moves the air in the movement path in a direction from the first opening toward the second opening. In the liquid ejection device according to the related art, when the pump is driven, air is discharged from the second opening, and the air is heated and humidified in the water and rises from the water surface, thereby generating the humidified air.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the liquid dispensing device relating to the above-mentioned related technology, there is inefficiency in the movement path of the humidified air from the water surface to the first opening. Therefore, in the liquid dispensing device relating to the above-mentioned related technology, the temperature of the humidified air decreases unnecessarily before it is supplied to the sealed space along the nozzle surface.

[0006] The object of the present invention is to provide a liquid dispensing device that can suppress the temperature drop of humidified air supplied to a sealed space along the nozzle surface. [Means for solving the problem]

[0007] The liquid dispensing device according to the present invention comprises a dispensing unit, a sealing unit, a tank, a heater, a path forming unit, and a pump. The dispensing unit has a nozzle surface on which a nozzle is formed, and dispenses liquid from the nozzle. The sealing unit seals the space along the nozzle surface. The tank stores water. The heater heats the water stored in the tank. The path forming unit forms an air movement path from a first opening that opens above the water surface of the water stored in the tank, through a sealed space sealed by the sealing unit, to a second opening that opens below the water surface. The pump moves the air in the movement path in the direction from the first opening to the second opening. The first opening and the second opening are positioned such that the first opening faces a specific range on the water surface where the air discharged from the second opening rises to the surface. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress the temperature drop of humidified air supplied to a sealed space along the nozzle surface. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a cross-sectional view showing the configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] Figure 2 is a perspective view showing the configuration of the head unit of an image forming apparatus according to an embodiment of the present invention. [Figure 3] Figure 3 is a perspective view showing the configuration of the cap unit of an image forming apparatus according to an embodiment of the present invention. [Figure 4] Figure 4 is a cross-sectional view showing the configuration of the humidification section of an image forming apparatus according to an embodiment of the present invention. [Figure 5] Figure 5 is a cross-sectional view showing a modified example of the humidification section of an image forming apparatus according to an embodiment of the present invention. [Modes for carrying out the invention]

[0010] The embodiments of the present invention will be described below with reference to the attached drawings. Note that the following embodiments are merely examples of the present invention and do not limit the technical scope of the present invention.

[0011] [Configuration of the image forming apparatus 100] First, the configuration of the image forming apparatus 100 according to an embodiment of the present invention will be described with reference to Figures 1 to 3.

[0012] For the sake of explanation, the vertical direction is defined as the up-down direction D1 when the image forming apparatus 100 is in a usable installation state (as shown in Figure 1). The front-to-back direction D2 is defined with the front side of the image forming apparatus 100 shown in Figure 1 being the front. The left-to-right direction D3 is defined with the front of the image forming apparatus 100 in the aforementioned installation state as the reference point.

[0013] The image forming apparatus 100 is an inkjet printer capable of forming an image on a sheet using an inkjet method. The image forming apparatus 100 is an example of the liquid ejection apparatus of the present invention. The ink is an example of the liquid of the present invention.

[0014] As shown in Figure 1, the image forming apparatus 100 comprises a paper feeding unit 1, an image forming unit 2, and a maintenance unit 3.

[0015] The paper feeding unit 1 supplies sheets to the image forming unit 2.

[0016] As shown in FIG. 1, the sheet feeding unit 1 includes a sheet feeding cassette 11 and a sheet feeding unit 12. The sheet feeding cassette 11 accommodates sheets on which images are formed by the image forming unit 2. The sheet feeding unit 12 takes out the uppermost sheet among a plurality of sheets (sheet bundle) accommodated in the sheet feeding cassette 11 and conveys the taken-out sheet to the downstream side of the conveyance path 13 (see FIG. 1). In the image forming apparatus 100, sheets are conveyed along the conveyance path 13 (see FIG. 1) from the sheet feeding cassette 11 via the image forming unit 2. In FIG. 1, the conveyance path 13 is indicated by a dashed-dotted line.

[0017] The image forming unit 2 forms an image on the sheet supplied by the sheet feeding unit 1 by an inkjet method.

[0018] As shown in FIG. 1, the image forming unit 2 includes a head unit 21 and a conveyance unit 22.

[0019] As shown in FIGS. 1 and 2, the head unit 21 includes four line heads 31 and a support unit 32.

[0020] As shown in FIG. 2, each of the line heads 31 is long in the width direction D5 (see FIG. 2) (the same direction as the front-rear direction D2) orthogonal to the sheet conveyance direction D4 (see FIG. 2). Specifically, each of the line heads 31 has a length corresponding to the width of the largest-size sheet among the sheets that can be accommodated in the sheet feeding cassette 11 in the width direction D5. The four line heads 31 are provided side by side at equal intervals along the conveyance direction D4.

[0021] In the image forming apparatus 100, images are formed using four colors of ink: black, cyan, magenta, and yellow. The ink is aqueous ink whose main solvent is water. The four line heads 31 are provided corresponding to the four ink colors.

[0022] As shown in Figure 2, each line head 31 is equipped with three recording heads 33. The recording heads 33 eject ink toward the sheet being transported by the transport unit 22. Specifically, the surface (bottom surface) of the recording head 33 facing the sheet is provided with numerous nozzles 34 (see Figure 4) used for ejecting ink. The recording head 33 ejects ink from each of the nozzles 34. Hereinafter, the surface of the recording head 33 on which the nozzles 34 are formed will be referred to as the "nozzle surface 33A" (see Figures 1 and 4). The recording head 33 is an example of the ejection unit of the present invention.

[0023] As shown in Figure 2, in each line head 31, the three recording heads 33 are arranged in a staggered pattern along the width direction D5.

[0024] The support section 32 supports four line heads 31. As shown in Figure 2, the support section 32 is formed in a flat plate shape along a horizontal plane. The support section 32 includes a mounting section corresponding to each recording head 33. The mounting section includes a through-hole that penetrates the support section 32 in the vertical direction D1. The bottom portion of the recording head 33 mounted on the mounting section, including the nozzle surface 33A, protrudes downward from the through-hole of the mounting section (see Figure 1).

[0025] The head unit 21 is provided to be movable between an image forming position and a retracted position. In Figure 1, the head unit 21 positioned at the image forming position is shown by a solid line. Also in Figure 1, the head unit 21 positioned at the retracted position is shown by a dashed line. The image forming position is the position of the head unit 21 when an image forming process is performed to form an image on a sheet. The retracted position is a position above the image forming position and is a position retracted above the movement paths of the wipe unit 52 (see Figure 1) and the cap unit 53 (see Figure 1), which move along the left-right direction D3. In other words, the head unit 21 is provided to be movable in the vertical direction D1.

[0026] Specifically, the support unit 32 is supported by the housing of the image forming apparatus 100 so as to be movable in the vertical direction D1. The support unit 32 moves in the vertical direction D1 by receiving a driving force supplied from a drive unit (not shown). As the support unit 32 moves, the four line heads 31 supported by the support unit 32 also move.

[0027] Furthermore, the number of line heads 31 provided in the head unit 21 is not limited to four. Also, the number of recording heads 33 included in the line head 31 is not limited to three.

[0028] As shown in Figure 1, the transport unit 22 is positioned below the head unit 21. The transport unit 22 transports the sheet while keeping it facing the recording head 33. As shown in Figure 1, the transport unit 22 includes a transport belt 41 on which the sheet is placed, and a plurality of tension rollers that tension the transport belt 41. The gap between the transport belt 41 and the nozzle surface 33A of the recording head 33 is adjusted so that the gap between the surface of the sheet and the nozzle surface 33A during image formation is a predetermined distance (for example, 1 mm).

[0029] Maintenance unit 3 is used for maintenance of the head unit 21.

[0030] As shown in Figure 1, the maintenance unit 3 comprises a storage unit 51, a wipe unit 52, and a cap unit 53.

[0031] As shown in Figure 1, the housing section 51 is positioned to the left of the image forming section 2. The housing section 51 houses the wipe unit 52 and the cap unit 53. The housing section 51 is formed in the shape of a hollow rectangular parallelepiped with the right side open.

[0032] The wipe unit 52 performs a wiping process to wipe the nozzle surface 33A. The wipe unit 52 includes a wipe section corresponding to each of the recording heads 33, and a support section that supports each of the wipe sections. The support section is formed in a flat plate shape along a horizontal plane. Each of the wipe sections is positioned on the upper surface of the support section.

[0033] The wipe unit 52 is provided to be movable between a first housing position and a wipe position. Figure 1 shows the wipe unit 52 positioned in the first housing position. As shown in Figure 1, the first housing position is the position in which the wipe unit 52 is housed in the housing section 51. The wipe position is the position in which the wipe unit 52 is positioned when the wiping process is performed. The wipe position is to the right of the first housing position. The wipe position is also a position between the image forming position and the retracted position. In other words, the wipe unit 52 is provided to be movable in the left-right direction D3.

[0034] Specifically, the support portion of the wipe unit 52 is supported by the housing of the image forming apparatus 100 so as to be movable in the left-right direction D3. The support portion moves in the left-right direction D3 by receiving a driving force supplied from a drive unit (not shown).

[0035] In the image forming apparatus 100, when the wiping process is to be performed, the operating mode of the image forming apparatus 100 transitions from an image forming mode capable of performing the image forming process to a wiping mode capable of performing the wiping process, in the following procedure. First, the head unit 21 is moved from the image forming position to the retracted position. Next, the wipe unit 52 is moved from the first housing position to the wipe position. Then, the head unit 21 is moved downward from the retracted position until the nozzle surface 33A and the wipe portion of the wipe unit 52 come into contact. This makes the wiping process possible.

[0036] The cap unit 53 caps the nozzle surface 33A. As shown in Figure 3, the cap unit 53 comprises a cap portion 61 corresponding to each recording head 33, and a support portion 62 that supports each cap portion 61. As shown in Figure 3, the support portion 62 is formed in a flat plate shape along a horizontal plane. The support portion 62 is made of metal. Each cap portion 61 is positioned on the upper surface of the support portion 62. Each cap portion 61 seals the space along the nozzle surface 33A. In other words, each cap portion 61 caps the nozzle surface 33A. As shown in Figure 3, the cap portion 61 comprises a bottom portion 61A and a peripheral wall portion 61B. The bottom portion 61A forms a facing surface that faces the nozzle surface 33A. The peripheral wall portion 61B is formed along the edge of the bottom portion 61A. The peripheral wall portion 61B seals the space between the nozzle surface 33A and the bottom surface portion 61A by surrounding it on all four sides (front, back, left, and right). The cap portion 61 is formed of an elastically deformable material such as rubber. When the nozzle surface 33A is capped, the cap portion 61 is pressed against the nozzle surface 33A from below. This forms a sealed space SP1 (see Figure 4) surrounded by the nozzle surface 33A, the bottom surface portion 61A, and the peripheral wall portion 61B. The cap portion 61 is an example of a sealed portion of the present invention.

[0037] The cap unit 53 is provided to be movable between a second housing position and a cap position. Figure 1 shows the cap unit 53 positioned in the second housing position. As shown in Figure 1, the second housing position is the position in which the cap unit 53 is housed in the housing portion 51. The cap position is the position in which the cap portion 61 covers the space along the nozzle surface 33A. The cap position is to the right of the second housing position. The cap position is also a position between the image forming position and the retracted position. In other words, the cap unit 53 is provided to be movable in the left-right direction D3. The second housing position is also a position retracted from the cap position. The cap position is an example of the first position of the present invention. The second housing position is an example of the second position of the present invention.

[0038] Specifically, the support portion 62 of the cap unit 53 is supported by the housing of the image forming apparatus 100 so as to be movable in the left-right direction D3. The support portion 62 moves in the left-right direction D3 by receiving a driving force supplied from a drive unit (not shown).

[0039] In the image forming apparatus 100, when the nozzle surface 33A is capped, the operating mode of the image forming apparatus 100 transitions from the image forming mode to the capped mode in which the nozzle surface 33A is capped, according to the following procedure. First, the head unit 21 is moved from the image forming position to the retracted position. Next, the cap unit 53 is moved from the second housing position to the cap position. Then, the head unit 21 is moved downward from the retracted position until the nozzle surface 33A is pressed against the cap portion 61 of the cap unit 53. This caps the nozzle surface 33A.

[0040] In the cap mode, humidified air is supplied into the sealed space SP1 (see Figure 4) which is sealed by the cap portion 61.

[0041] Specifically, the cap unit 53 includes a humidifying unit 63 (see Figure 4) corresponding to each of the recording heads 33.

[0042] [Configuration of the humidifier unit 63] Next, the configuration of the humidifying unit 63 will be described with reference to Figure 4. Here, Figure 4 is a cross-sectional view showing the cap portion 61 and the humidifying unit 63 with the nozzle surface 33A capped.

[0043] The humidifying unit 63 supplies humidified air into a sealed space SP1 (see Figure 4) that is sealed by the cap unit 61.

[0044] As shown in Figure 4, the humidification unit 63 includes a tank 71, a heater 72, a first air passage 73, a second air passage 74, a third air passage 75, and a pump 76.

[0045] Tank 71 stores water WA1 (see Figure 4).

[0046] As shown in Figure 4, the tank 71 is attached to the bottom surface of the support 62. The tank 71 is formed in the shape of a hollow rectangular parallelepiped with the top side open. The tank 71 is attached to the bottom surface of the support 62 such that the top opening is closed by the bottom surface of the support 62. A predetermined amount of water WA1 is stored inside the tank 71.

[0047] The heater 72 heats the water WA1 stored in the tank 71.

[0048] As shown in Figure 4, the heater 72 is provided on the outer surface of the tank 71. The heater 72 generates heat in response to power supply. The heater 72 is driven by a control unit (not shown). Specifically, the control unit controls the drive of the heater 72 so that the temperature of the water WA1 in the tank 71, as detected by a temperature sensor (not shown), reaches a predetermined temperature.

[0049] The first air passage 73 is a passage for air to move from the upper space above the water surface WA2 (see Figure 4) of the water WA1 stored in the tank 71 to the through hole 61C (see Figure 4) formed in the bottom surface 61A of the cap portion 61. For example, the first air passage 73 is a resin tube that extends from the through hole 61C through a through hole formed in the support portion 62 into the tank 71. The end of the first air passage 73 on the tank 71 side forms an air intake port 73A (see Figure 4) that opens above the water surface WA2 of the water WA1 stored in the tank 71.

[0050] The second air passage 74 is a passage for air to move from the through hole 61D (see Figure 4) formed in the bottom surface 61A of the cap portion 61 to the pump 76. For example, the second air passage 74 is a resin tube that extends from the through hole 61D through a through hole formed in the support portion 62 into the pump 76.

[0051] The third air passage 75 is a passage for air to travel from the pump 76 to the water below the water level WA2 (see Figure 4) of the water WA1 stored in the tank 71. For example, the third air passage 75 is a resin tube that extends from the pump 76 to the inside of the pump 76 through two through holes formed in the support part 62. The end of the third air passage 75 on the tank 71 side forms an exhaust port 75A (see Figure 4) that opens below the water level WA2 of the water WA1 stored in the tank 71.

[0052] As shown in Figure 4, the first air passage 73, the cap portion 61, the nozzle surface 33A of the recording head 33, the second air passage 74, the pump 76, and the third air passage 75 form an air movement path from the intake port 73A through the sealed space SP1 to the exhaust port 75A. The first air passage 73, the cap portion 61, the nozzle surface 33A of the recording head 33, the second air passage 74, the pump 76, and the third air passage 75 are examples of path-forming parts of the present invention. The intake port 73A is an example of a first opening of the present invention. The exhaust port 75A is an example of a second opening of the present invention.

[0053] Pump 76 moves the air in the air movement path from the intake port 73A through the sealed space SP1 to the exhaust port 75A in the direction of movement D6 (see Figure 4) from the intake port 73A to the exhaust port 75A. A check valve (not shown) is provided in the third air passage 75 to prevent backflow of water WA1 in the tank 71 to the pump 76 side.

[0054] In the humidification unit 63, the pump 76 is driven, causing air to be discharged from the exhaust port 75A. The discharged air is heated and humidified in the water WA1 and rises above the water surface WA2, thereby generating humidified air. This generated humidified air is then supplied to the sealed space SP1 via the first air passage 73. This prevents the ink inside the nozzle 34 from drying out inside the cap of the nozzle surface 33A.

[0055] Incidentally, if there is inefficiency in the path of humidified air from the water surface WA2 to the air intake port 73A, the temperature of the humidified air will decrease unnecessarily before it is supplied to the sealed space SP1. For example, if the humidified air that has risen from the water surface WA2 comes into contact with the metal support part 62 before moving to the air intake port 73A, the temperature of the humidified air will decrease. When the temperature of the humidified air supplied to the sealed space SP1 decreases, the humidity inside the sealed space SP1 decreases, making it impossible to adequately suppress the drying of the ink in the nozzle 34.

[0056] In contrast, the image forming apparatus 100 according to the embodiment of the present invention can suppress the temperature drop of the humidified air supplied to the sealed space SP1, as described below.

[0057] Specifically, in the humidification unit 63, the intake port 73A and exhaust port 75A are positioned such that the intake port 73A faces a specific range AR1 (see Figure 4) on the water surface WA2 where the air discharged from the exhaust port 75A rises to the surface. This eliminates waste in the movement path of humidified air from the water surface WA2 to the intake port 73A. Note that in Figure 4, the specific range AR1 is shown by a dashed line.

[0058] The specific range AR1 may be determined based on the depth of the exhaust port 75A (distance along the vertical direction D1 from the water surface WA2), the orientation of the exhaust port 75A, and the wind speed in the third air passage 75 when air is discharged from the exhaust port 75A by the pump 76. Alternatively, the specific range AR1 may be determined based on the results of an experiment investigating the position of the air that rises above the water surface WA2 after being discharged from the exhaust port 75A by the pump 76.

[0059] The air intake port 73A should preferably be located near the center of the specific range AR1, with an opening that faces downwards. This allows for efficient intake of humidified air generated within the specific range AR1.

[0060] In the image forming apparatus 100, the exhaust port 75A is provided to open in a direction intersecting the vertical direction. Specifically, as shown in Figure 4, the exhaust port 75A opens toward the rear of the image forming apparatus 100. This makes it possible to space a specific range AR1 away from the exhaust port 75A in a direction along the horizontal plane, compared to a configuration in which the exhaust port 75A opens in a direction along the vertical direction (up or down), as shown in Figure 5. In other words, it is possible to increase the distance between the intake port 73A and the exhaust port 75A in a direction along the horizontal plane, thereby increasing the degree of freedom in the placement of the intake port 73A and the exhaust port 75A.

[0061] Furthermore, in the image forming apparatus 100, the tank 71 is attached to the support portion 62 of the cap portion 61. In other words, the tank 71 is provided to be movable integrally with the cap portion 61. This makes it possible to reduce the distance between the tank 71 and the cap portion 61 compared to a configuration in which the tank 71 is fixedly positioned within the housing of the image forming apparatus 100. In other words, it is possible to shorten the supply path of humidified air from the tank 71 to the cap portion 61. Consequently, compared to a configuration in which the tank 71 is fixedly positioned within the housing of the image forming apparatus 100, it is possible to suppress the temperature drop of the humidified air supplied to the sealed space SP1.

[0062] The humidification unit 63 may be provided for each line head 31. In this case, the first air passage 73 should be configured to connect the tank 71 with each of the recording heads 33 included in the line head 31. The second air passage 74 should be configured to connect each of the recording heads 33 included in the line head 31 with the pump 76.

[0063] [Notes on the invention] The following is an overview of the invention extracted from the above-described embodiments. Note that each configuration and processing function described below can be selected and combined as desired.

[0064] <Note 1> A liquid discharge device comprising: a discharge unit having a nozzle surface on which a nozzle is formed and for discharging liquid from the nozzle; a sealing unit for sealing a space along the nozzle surface; a tank for storing water; a heater for heating the water stored in the tank; a path forming unit for forming an air movement path from a first opening that opens above the water surface of the water stored in the tank, through a sealed space sealed by the sealing unit, to a second opening that opens below the water surface; and a pump for moving the air in the movement path in the direction from the first opening to the second opening, wherein the first opening and the second opening are positioned such that the first opening faces a specific range on the water surface where air discharged from the second opening rises to the surface.

[0065] <Note 2> The liquid dispensing device described in Appendix 1, wherein the second opening is oriented in a direction intersecting the vertical direction.

[0066] <Note 3> The liquid dispensing device according to Appendix 1 or 2, wherein the sealing portion includes a cap portion that is movable between a first position covering the space along the nozzle surface and a second position retracted from the first position, and the tank is provided to be movable integrally with the cap portion. [Explanation of symbols]

[0067] 1 Paper feed section 2 Image forming unit 3. Maintenance Department 21 Head Unit 22 Conveyor Units 31 Line Head 32 Support part 33 Recording head 33A Nozzle surface 34 nozzles 51 Storage Unit 52 wipe units 53 Cap Unit 61 Cap section 62 Support part 63 Humidification section 71 tanks 72 Heater 73 First air passage 73A Air intake 74 Second air passage 75 Third air passage 75A Exhaust port 76 pumps 100 Image forming apparatus

Claims

1. A discharge section having a nozzle surface on which a nozzle is formed, and which discharges liquid from the nozzle, A sealing portion that seals the space along the nozzle surface, A tank for storing water, A heater for heating the water stored in the tank, A path forming unit that forms an air movement path from a first opening that opens above the water surface of the water stored in the tank, through a sealed space sealed by the sealing unit, to a second opening that opens below the water surface, A pump that moves the air in the aforementioned transport path in the direction from the first opening to the second opening, Equipped with, The first opening and the second opening are positioned such that the first opening faces a specific range on the water surface where air discharged from the second opening rises to the surface. Liquid discharge device.

2. The second opening is oriented in a direction intersecting the vertical direction. The liquid dispensing device according to claim 1.

3. The sealing portion includes a cap portion that is movable between a first position covering the space along the nozzle surface and a second position retracted from the first position. The tank is provided so as to be movable together with the cap portion. The liquid dispensing device according to claim 1 or 2.

Images