Inkjet recording device

Abstract

To provide an inkjet recording device that allows checking the remaining ink level in the tank during emergencies. [Solution] The inkjet recording device comprises a recording head, a tank, and a liquid channel. The recording head has multiple nozzles that eject ink onto a recording medium. The tank temporarily stores ink supplied from a container and supplies the stored ink to the recording head. The liquid channel connects the container and the tank, through which the ink flows. The liquid channel has a supply channel and a branch channel. The supply channel is connected to the bottom of the tank and supplies ink from the container to the tank. The branch channel branches off from the supply channel and is connected to the top of the container. The branch channel is transparent.

Description

Technical Field

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

Background Art

[0002] A conventional inkjet recording apparatus is an inkjet recording apparatus including a recording head, a tank, a liquid flow path, and a float sensor. The recording head has a plurality of nozzles that eject ink onto a recording medium. The tank temporarily stores ink supplied from a container and supplies the stored ink to the recording head. The liquid flow path connects the container and the tank to allow ink to flow therethrough. The water level sensor detects the height of the liquid surface of the ink in the tank.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the inkjet recording apparatus disclosed in the above Patent Document 1, the tank is made of a highly light-shielding material to protect the ink stored therein, and there is a possibility that the remaining amount of ink in the tank cannot be confirmed in an emergency including when the float sensor malfunctions or the power of the printer is turned off.

[0005] An object of the present invention is to provide an inkjet recording apparatus that allows the remaining amount of ink in a tank to be confirmed in an emergency.

Means for Solving the Problems

[0006] To achieve the above objective, the first configuration of the present invention is an inkjet recording apparatus comprising a recording head, a tank, and a liquid channel. The recording head has a plurality of nozzles for ejecting ink onto a recording medium. The tank temporarily stores ink supplied from a container and supplies the stored ink to the recording head. The liquid channel connects the container and the tank, through which the ink flows. The liquid channel has a supply channel and a branch channel. The supply channel is connected to the bottom of the tank and supplies ink from the container to the tank. The branch channel branches off from the supply channel and is connected to the top of the container. The branch channel is transparent. [Effects of the Invention]

[0007] According to the first configuration of the present invention, an inkjet recording device can be provided that allows the remaining amount of ink in the tank to be checked in an emergency. [Brief explanation of the drawing]

[0008] [Figure 1] This is an explanatory diagram showing the schematic configuration of a printer as an inkjet recording device according to one embodiment of the present invention. [Figure 2] This is a plan view of the recording unit of the printer according to this embodiment. [Figure 3] This is a block diagram of the printer according to this embodiment. [Figure 4] This is an explanatory diagram illustrating the liquid supply mechanism of the printer according to this embodiment. [Figure 5] This is an explanatory diagram illustrating the tank of the printer according to this embodiment. [Modes for carrying out the invention]

[0009] [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.

[0010] A paper supply unit 3 is located on the downstream side of the paper transport direction of the paper feed cassette 2, that is, above and to the right of the paper feed cassette 2 in Figure 1. This paper supply unit 3 separates and feeds out the paper P one sheet at a time, directed towards the upper right of the paper feed cassette 2 in Figure 1.

[0011] 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.

[0012] 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 paper 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 paper transport unit 5.

[0013] The paper P, fed to the paper transport unit 5 by the registration roller pair 13, is transported by a transport belt (not shown) 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 in the recording unit 9 is controlled by the control unit 110 inside the printer 100.

[0014] The control unit 110 includes a CPU, a memory unit, and other electronic circuits and electronic components (none of which are shown). The CPU controls the operation of each component provided in the printer 100 based on control programs and data stored in the memory unit, and performs processing related to the functions of the printer 100. The memory unit consists of a combination of non-volatile storage devices such as program ROM (Read Only Memory) and data ROM, and volatile storage devices such as RAM (Random Access Memory).

[0015] In the paper transport direction, the drying unit 12 is located downstream of the paper transport unit 5 (left side in Figure 1). The paper P on which the image has been recorded by the recording unit 9 is sent to the drying unit 12. The ink ejected onto the surface of the paper P is dried as it passes through the drying unit 12.

[0016] In the paper transport direction, a de-curler unit 14 is provided downstream of the drying unit 12 and near the left side of the printer body 1. The paper P, whose ink has been dried by the drying unit 12, is sent to the de-curler unit 14 to correct any curl that has formed on the paper P.

[0017] In the paper transport direction, a second paper transport path 4b is provided downstream of the decurler unit 14 (upper part of Figure 1). If double-sided recording is not performed, the paper P that has passed through the decurler unit 14 passes through the second paper transport path 4b and is discharged into a paper output tray 15 located on the left side outside the printer 100.

[0018] An inversion transport path 16 for double-sided recording is provided at the top of the printer body 1, above the recording unit 9 and the drying unit 12. When double-sided recording is performed, after recording on one side (first side) of the paper P is completed and the paper P has passed through the drying unit 12 and the decurler unit 14, it is sent to the inversion transport path 16 via the second paper transport path 4b.

[0019] The paper P sent to the reverse conveyance path 16 has its conveyance direction switched for recording on the other side (the second side) of the paper P. Then, the paper P passes through the upper part of the printer main body 1, is sent toward the right side, passes through the pair of registration rollers 13, and is sent again to the paper conveyance unit 5 with the second side facing upward. In the paper conveyance unit 5, the paper P is conveyed to a position facing the recording unit 9, and an image is recorded on the second side by ink ejection from the recording unit 9. The paper P after double-sided recording sequentially passes through the drying unit 12, the decurler unit 14, and the second paper conveyance path 4b, and is discharged to the paper discharge tray 15.

[0020] Further, below the drying unit 12, a maintenance unit 19 and a cap unit 20 are arranged. The maintenance unit 19 horizontally moves below the recording unit 9 when performing purging, wipes off the ink extruded from the nozzles 18a (see FIG. 2) of the recording heads 17a to 17c, and collects the wiped ink. Note that purging refers to an operation of forcibly extruding ink from the nozzles 18a of the recording heads 17a to 17c in order to discharge thickened ink, foreign matter, air bubbles and the like in the nozzles 18a.

[0021] The cap unit 20 horizontally moves below the recording unit 9 when capping the ink ejection surfaces of the recording heads 17a to 17c, further moves upward, and is attached to the lower surfaces of the recording heads 17a to 17c.

[0022] FIG. 2 is a plan view of the recording unit 9 of the printer 100. The recording unit 9 includes a head housing 10, and line heads 11C, 11M, 11Y, and 11K held by the head housing 10. These line heads 11C to 11K are supported at such a height that a predetermined interval (for example, 1 mm) is formed with respect to the conveyance surface of a conveyance belt (not shown), and as shown in FIG. 1, a plurality (three in this case) of recording heads 17a to 17c are arranged in a zigzag pattern along the paper width direction (the vertical direction in FIG. 1) orthogonal to the paper conveyance direction (the arrow X direction).

[0023] Each recording head 17a to 17c, which makes up each line head 11C to 11K, is supplied with four colors of ink (cyan, magenta, yellow, and black) stored in an ink tank (not shown), according to the color of each line head 11C to 11K.

[0024] Each recording head 17a to 17c, in response to control signals from the control unit 110 (see Figure 1), ejects ink from its nozzle 18a toward the paper P being transported by being held and adsorbed onto the transport surface of the transport belt (not shown), according to the image data received from an external computer. As a result, a color image is formed on the paper P on the transport belt by superimposing four colors of ink: cyan, magenta, yellow, and black.

[0025] Figure 3 is a block diagram of printer 100, and Figure 4 is an explanatory diagram of the liquid supply mechanism of printer 100. Printer 100 is equipped with an ink supply unit 8. The ink supply unit 8 is provided individually for each of the four color line heads 11C to 11K. In the following description, the identification symbols representing each color will be omitted.

[0026] Between the ink supply unit 8 and the recording heads 17a to 17c, there is a built-in valve member (not shown) that opens the ink flow path when connected and closes the ink flow path when disconnected.

[0027] The ink supply unit 8 includes a container 81, a container pump 82, a tank 83, a syringe 84, a first flow path 85, a second flow path 86, a third flow path 89, a connecting flow path 87, an opening / closing mechanism 88, a first opening / closing valve 91, a second opening / closing valve 92, a third opening / closing valve 93, and a liquid flow path 94. In other words, the printer 100 includes a tank 83 and a liquid flow path 94.

[0028] Container 81 is detachably attached to the printer body 1. Container 81 contains the ink supplied to the recording heads 17a to 17c.

[0029] The container pump 82 is positioned downstream of the container 81 in the ink flow direction. The container pump 82 draws ink from the container 81 and discharges it toward the tank 83. The operation of the container pump 82 is controlled by the control unit 110.

[0030] Tank 83 is positioned downstream of the container pump 82 in the ink flow direction. Tank 83 temporarily stores the ink supplied from container 81 and supplies the stored ink to the recording heads 17a to 17c. Tank 83 is equipped with an ink level sensor 96 (see Figure 5). The ink level sensor includes, for example, optical, capacitive, electrode, differential pressure, and float sensors, and detects the height of the ink level in tank 83. In this embodiment, a float sensor is used as the ink level sensor 96 (see Figure 5).

[0031] The control unit 110 receives a detection signal from the ink level sensor of tank 83. When the amount of ink in tank 83 detected by the ink level sensor 96 falls below a predetermined value, the control unit 110 controls the container pump 82 to supply ink from container 81 to tank 83. The amount of ink supplied from container 81 to tank 83 is controlled, for example, by the operating time of the container pump 82. If the amount of ink in tank 83 detected by the ink level sensor 96 does not rise above a predetermined value even after a certain period of time has elapsed since the container pump 82 was operated, the control unit 110 determines that the ink level in container 81 is empty.

[0032] Syringe 84 is positioned downstream of tank 83 in the ink flow direction and upstream of recording heads 17a-17c in the ink flow direction. Ink flows into syringe 84 from tank 83 and flows out toward recording heads 17a-17c.

[0033] The third channel 89 extends from the syringe 84 to the tank 83. The third channel 89 is an air channel that discharges the air inside the syringe 84 to the tank 83.

[0034] The third on-off valve 93 is positioned on the third flow path 89. The third on-off valve 93 opens and closes the third flow path 89. The third on-off valve 93 is, for example, a solenoid valve, and its opening and closing is controlled by the control unit 110. The control unit 110 opens the third on-off valve 93 when air is discharged from the syringe 84.

[0035] When recording an image onto paper P, recording pressure is applied to the ink due to the action of hydrostatic pressure. In contrast, during maintenance, for example, the control unit 110 can apply a maintenance pressure higher than the recording pressure to the ink by pushing ink out from within the syringe 84.

[0036] The first channel 85, the second channel 86, and the connecting channel 87 are ink channels through which ink circulates from the tank 83 through the recording heads 17a to 17c back to the tank 83. The first channel 85 is an ink channel through which ink flows from the tank 83 through the syringe 84 to the recording heads 17a to 17c.

[0037] The first on-off valve 91 is positioned on the first flow path 85, upstream of the syringe 84 in the ink flow direction. The second on-off valve 92 is positioned on the first flow path 85, downstream of the syringe 84 in the ink flow direction. The first flow path 85 is a tube made of, for example, rubber, and can be bent or flexed to deform it. The opening and closing of the first on-off valve 91 and the second on-off valve 92 are controlled by the control unit 110. The first on-off valve 91 opens and closes the first flow path 85 between the syringe 84 and the tank 83. The second on-off valve 92 opens and closes the first flow path 85 between the syringe 84 and the recording heads 17a to 17c.

[0038] The second flow path 86 is an ink flow path through which ink flows from the recording heads 17a to 17c to the tank 83.

[0039] The communication channel 87 connects the upstream side of the recording heads 17a to 17c with respect to the ink flow direction of the first channel 85, and the downstream side of the recording heads 17a to 17c with respect to the ink flow direction of the second channel 86.

[0040] The opening / closing mechanism 88 is positioned on the communication channel 87. The opening / closing mechanism 88 is, for example, composed of a solenoid valve, and its opening and closing is controlled by the control unit 110. The opening / closing mechanism 88 opens and closes the communication channel 87.

[0041] When the printer 100 starts the process of replacing ink with a different ink, the control unit 110 discharges the ink present in tank 83 from recording heads 17a to 17c. At this time, the control unit 110 discharges the ink from recording heads 17a to 17c by the extrusion operation of syringe 84. The amount of ink in tank 83 is detected, for example, by the ink level sensor 96 of tank 83.

[0042] The control unit 110 expels the ink present in the syringe 84 from the recording heads 17a to 17c by pushing the syringe 84 out. As a result, the control unit 110 expels the ink in the tank 83 and the ink flow path from the recording heads 17a to 17c.

[0043] The control unit 110 drives the container pump 82 to supply ink from the container 81 to the tank 83.

[0044] The control unit 110 performs an air purging operation in the syringe 84 and fills the syringe 84 with ink. For example, when performing the air purging operation in the syringe 84, the control unit 110 closes the first on-off valve 91 and the second on-off valve 92 and opens the third on-off valve 93, and performs an extrusion operation of the syringe 84. As a result, the air in the syringe 84 is discharged through the third flow path 89.

[0045] When filling the syringe 84 with ink, the control unit 110 opens the first on-off valve 91 and the third on-off valve 93 and closes the second on-off valve 92. Furthermore, the control unit 110 performs a suction operation on the syringe 84. As a result, ink is filled into the syringe 84 from the tank 83.

[0046] The control unit 110 controls the opening / closing mechanism 88 to open the communication channel 87 and performs a first circulation operation to circulate the ink within the ink channel. At this time, the control unit 110 performs suction and extrusion operations of the syringe 84. As a result, the ink circulates within the ink channel.

[0047] The control unit 110 controls the opening / closing mechanism 88 to close the communication channel 87 and executes the suction and extrusion operations of the syringe 84. As a result, ink circulates within the ink channel.

[0048] The control unit 110 performs the operation of removing air from the syringe 84, filling the syringe 84 with ink, and circulating the ink into the ink channel with the communication channel 87 closed.

[0049] The control unit 110 discharges (purges) the ink from the recording heads 17a to 17c. At this time, the control unit 110 discharges (purges) the ink from the recording heads 17a to 17c by the pushing operation of the syringe 84.

[0050] The control unit 110 discharges the ink present in the tank 83 and syringe 84 from the recording heads 17a to 17c. At this time, the control unit 110 discharges the ink from the recording heads 17a to 17c by the pushing action of the syringe 84.

[0051] Figure 5 is an explanatory diagram illustrating the tank 83. Note that the first flow path 85, the second flow path 86, and the third flow path 89 are not shown in Figure 5. In this embodiment, the tank 83 has a storage section 831 for storing ink and a lid section 832 that closes the upper end surface of the storage section 831. The upper part of the storage section 831 protrudes laterally to form a projection 833.

[0052] Furthermore, the tank 83 is made of a metal or resin material that is highly flame-retardant and light-shielding. For this reason, the tank 83 is not transparent, and the ink level cannot be visually checked from the outside. The lid 832 has a communication hole (not shown) that connects the inside and outside of the tank 83.

[0053] In this embodiment, the water level sensor 96 is a float sensor and has a float 96a and a rail 96b. The rail 96b extends vertically, and the float 96a is supported by the rail 96b so as to be movable vertically. The float 96b floats on the ink level and moves up and down according to the height of the liquid level. The water level sensor 96 detects the height of the ink level in the tank 83 based on the position of the float 96a.

[0054] The container 81 and the tank 83 are connected via a liquid channel 94 through which ink flows. The liquid channel 94 has a supply channel 94a and a branch channel 94b. The supply channel 94a is connected to the bottom of the tank 83 and supplies ink from the container 81 to the tank 83. The branch channel 94b branches off from the supply channel 94a and is connected to the bottom of the protruding section 833. That is, the branch channel 94b is connected to the top of the container 83.

[0055] The liquid channel 94 is, for example, a tube made of rubber, and can be bent or flexed to deform it. The branch channel 94b is transparent and extends in the vertical direction. The ink level in the branch channel 94b is at the same height as the ink level in the tank 83. As a result, the amount of ink remaining in the tank 83 can be detected by visually checking the ink level in the transparent branch channel 94b. Therefore, in the event of a malfunction of the water level sensor 96 or when the printer 1 is powered off, the amount of ink remaining in the tank 83 can be accurately detected by checking the liquid level in the branch channel 94b.

[0056] The container pump 82 is positioned upstream of the branching point 94c with the branching channel 94b on the supply channel 94a in the ink flow direction, and supplies ink from the container 81 to the tank 83.

[0057] When the container pump 82 is driven to continuously supply ink to the tank 83 with the first on-off valve 91, the second on-off valve 92, and the third on-off valve 93 closed, the liquid level in the tank 83 rises. At this time, when the liquid level exceeds the bottom surface of the protrusion 833, the ink in the tank 83 flows into the branch channel 94b. The ink that returns to the branch channel 94b returns to the supply channel 94b. In other words, a portion of the ink supplied to the tank 83 via the supply channel 94a flows through the branch channel 94b and returns to the supply channel 94a. This allows the ink in the branch channel 94b to circulate, preventing the ink from drying and condensing at the liquid surface of the branch channel 94b, which is exposed to air. Therefore, a decrease in the function of the branch channel 94b as an indicator for detecting the remaining amount of ink in the tank 83 can be suppressed.

[0058] 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. The effects of the present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In this embodiment, the branch channel 94b is connected to the bottom surface of the tank 83, but it may also be connected to the lower side surface of the storage section 831. [Industrial applicability]

[0059] The present invention can be used in an inkjet recording device having a nozzle for ejecting ink onto a recording medium. [Explanation of Symbols]

[0060] 1. Printer body 1. Printer 2 Paper feed cassettes 3. Paper supply unit 4a First paper transport path 4b Second paper transport path 5. Paper transport section 8. Ink supply unit 9. Records Section 10 Head Housing 11C, 11M, 11Y line heads 11C~11K Line Head 12 Drying section 13 Resist Roller vs 14 Decaler section 15 Paper output tray 16 Reversal transport path 17a~17c Recording head 18a Nozzle 19 Maintenance Unit 20 Cap Units 81 containers 82 Container Pumps 83 containers 83 tanks 84 syringes 85 First channel 86 Second channel 87 Connecting channel 88 Opening and closing mechanism 89 Third channel 91 First shut-off valve 92 Second shut-off valve 93 Third shut-off valve 94 Liquid flow path 94a Supply channel 94b Branch channel 94c Branch 96 Ink level sensor 96 Water level sensor 96a Float 96b Rail 96b Float 100 Printers 110 Control Unit 831 Storage Unit 832 Lid 833 Protrusion P paper X arrow

Claims

1. A recording head having multiple nozzles for ejecting ink onto a recording medium, A tank for temporarily storing the ink supplied from the container and for supplying the stored ink to the recording head, The container and the tank are connected by a liquid flow path through which the ink flows, The aforementioned liquid channel is A supply channel connected to the bottom of the tank, which supplies the ink from the container to the tank, It has a branch channel that branches off from the supply channel and is connected to the top of the container, The aforementioned branch channel is transparent, and the device is an inkjet recording apparatus.

2. The inkjet recording apparatus according to claim 1, further comprising a container pump located upstream of the branching point with the branching channel on the supply channel, which supplies the ink from the container to the tank.

3. The inkjet recording apparatus according to claim 2, wherein, by driving the container pump, a portion of the ink supplied to the tank via the supply channel flows through the branch channel and returns to the supply channel.

4. The inkjet recording apparatus according to claim 1 or claim 2, further comprising a water level sensor for detecting the height of the ink level in the tank.

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