Float sensor and image formation device

Abstract

To prevent ink from fixing with a simple structure.SOLUTION: A float sensor includes: a float supported to a support part so as to move according to a liquid level position of ink in a container; a detection part for detecting the float in a predetermined liquid level position; and a first supply part for supplying ink so as to flow between the support part and the float.SELECTED DRAWING: Figure 3B

Description

[Technical field]

[0001] The present invention relates to a float sensor and an image forming apparatus. [Background technology]

[0002] 2. Description of the Related Art In an inkjet type image forming apparatus, a tank that stores ink to be supplied to an inkjet head is provided with a float sensor that detects the ink level (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-245815 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a float sensor, ink may accumulate and solidify between the float and the shaft that movably supports the float. If the ink solidifies, the float cannot move, and the liquid level detection does not function properly. This type of problem is likely to occur when the ink has the property of hardening through a hardening reaction caused by heat, ultraviolet light, etc.

[0005] To solve this problem, the technology disclosed in Patent Document 1 is configured so that the liquid refilled into the tank hits a float, and the momentum (force) of the liquid hitting the float moves the float and dissolves the solidified liquid with the refilled liquid. However, the technology disclosed in Patent Document 1 requires the liquid to be refilled with force, which causes a problem of the device becoming complicated.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a float sensor and an image forming apparatus that can prevent ink from sticking with a simple configuration. [Means for solving the problem]

[0007] The float sensor according to the present invention comprises: a float supported by a support so as to move in response to a liquid level of the ink in the container; A detection unit that detects the float at a predetermined liquid level position; a first supply section that supplies the ink to flow between the support section and the float; Equipped with.

[0008] The image forming apparatus according to the present invention comprises: A container for storing ink; an image forming unit that forms an image using the ink supplied from the container; The above float sensor, Equipped with. Effect of the Invention

[0009] According to the present invention, it is possible to prevent ink from sticking with a simple configuration. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus and a float sensor according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing a main part of a control system of the image forming apparatus shown in FIG. [Figure 3A] FIG. 3A is a top view illustrating the float sensor shown in FIG. [Figure 3B] FIG. 3B is a side view illustrating the float sensor shown in FIG. 1, showing a case where the liquid level is at a lower limit position. [Figure 3C] FIG. 3C is a side view illustrating the float sensor shown in FIG. 1, showing a case where the liquid level is at the supply stop position. [Figure 3D] FIG. 3D is a side view illustrating the float sensor shown in FIG. 1, showing the case where the liquid level is at the upper limit position. [Figure 4A]FIG. 4A is a side view illustrating a modified example (modification 1) of the float sensor shown in FIGS. 3A to 3D, showing the case where the liquid level is at the lower limit position. [Figure 4B] FIG. 4B is a side view for explaining a modified example (modification 1) of the float sensor shown in FIGS. 3A to 3D, showing the case where the liquid level is at the supply stop position. [Figure 4C] FIG. 4C is a side view illustrating the float sensor shown in FIGS. 3A to 3D, showing the case where the liquid level is at the upper limit position. [Figure 5A] FIG. 5A is a top view illustrating a modified example (modification 2) of the float sensor shown in FIGS. 4A to 4C. [Figure 5B] FIG. 5B is a side view illustrating a modified example (modification 2) of the float sensor shown in FIGS. 4A to 4C, showing the case where the liquid level is at the lower limit position. [Figure 6A] FIG. 6A is a top view illustrating a modification (Modification 3) of the float sensor shown in FIGS. 5A and 5B. [Figure 6B] FIG. 6B is a side view for explaining a modified example (modification 3) of the float sensor shown in FIGS. 5A and 5B, showing the case where the liquid level is at the lower limit position. [Figure 7A] FIG. 7A is a top view illustrating a modified example (modification 4) of the float sensor shown in FIGS. 3A to 3D. [Figure 7B] FIG. 7B is a side view illustrating a modified example (modification 4) of the float sensor shown in FIGS. 3A to 3D, showing the case where the liquid level is at the lower limit position. [Figure 7C] FIG. 7C is a side view illustrating a modification (modification 4) of the float sensor shown in FIGS. 3A to 3D, showing the case where the liquid level is at the upper limit position. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0012] [Image forming device] Fig. 1 is a schematic diagram illustrating an example of an inkjet printer 100 and a float sensor 440A according to the present embodiment. Fig. 2 is a block diagram showing the main parts of a control system of the inkjet printer 100 shown in Fig. 1.

[0013] As shown in FIG. 2, the inkjet printer 100 (image forming apparatus of the present invention) includes a transport section 10, a supply section 20, a discharge section 30, an ink supply section 40, a head module 50, an operation display section 70, an input / output interface 80, a control section 90, etc.

[0014] The conveying unit 10 conveys the recording medium M (see FIG. 1). The conveying unit 10 is composed of, for example, a conveying belt or a conveying drum. The recording medium M supplied from the supply unit 20 is conveyed to the head module 50 by the conveying operation of the conveying unit 10. The recording medium M on which an image has been formed by the head module 50 is conveyed to the discharge unit 30 by the conveying operation of the conveying unit 10.

[0015] The recording medium M can be any of various media capable of fixing ink ejected from an inkjet head (not shown) of the head module 50. The recording medium M is, for example, a medium such as sheet-shaped paper, cloth (woven fabric), or resin. Note that the recording medium M is not limited to a sheet-shaped medium, and may be a medium such as roll-shaped paper, cloth, or resin.

[0016] The supply unit 20 stores the recording medium M and supplies the recording medium M to the transport unit 10. The supply unit 20 has, for example, a storage unit that stores the recording medium M, and has a belt, rollers, etc. that transport the recording medium M to the transport unit 10.

[0017] The discharge unit 30 stores the recording medium M discharged from the transport unit 10. The discharge unit 30 has, for example, a belt or rollers that transport the recording medium M from the transport unit 10, and has a storage unit that stores the recording medium M.

[0018] The ink supply unit 40 is a device that supplies the ink I to the head module 50. The ink supply unit 40 has a first sub-tank unit 410, a liquid delivery unit 420, a second sub-tank unit 430, and the like.

[0019] The first sub-tank portion 410 stores the ink I to be sent to the second sub-tank portion 430. The first sub-tank portion 410 has a first sub-tank 411 that stores the ink I, and the like. The first sub-tank 411 is connected to a main tank (not shown) that stores the ink I, via a liquid sending path (not shown). The ink I stored in the main tank is sent to the first sub-tank 411 using a pump or the like (not shown).

[0020] The liquid sending unit 420 sends the ink I stored in the first sub-tank 411 to a second sub-tank unit 430 (a second sub-tank 431 described later). The liquid sending unit 420 has a tank supply path 421, a degassing module 422, a pump 423, a valve 424, and the like.

[0021] The tank supply path 421 connects the first sub-tank 411 and the second sub-tank 431, and serves as a flow path for the ink I from the first sub-tank 411 to the second sub-tank 431. The connection of the tank supply path 421 to the second sub-tank 431 will be described later. The degassing module 422 degasses the ink I to be delivered and filters the ink I.

[0022] The pump 423 is a pump that sends the ink I from the first sub-tank 411 to the second sub-tank 431. The valve 424 opens and closes the tank supply path 421. For example, when sending the ink I from the first sub-tank 411 to the second sub-tank 431, the valve 424 opens, and when sending the ink I from the second sub-tank 431 to the head module 50, the valve 424 closes.

[0023] The second sub-tank portion 430 stores the ink I to be sent to the head module 50. The second sub-tank portion 430 has a second sub-tank 431 that stores the ink I, an air pressure pump 432, a head supply path 433, a temperature control portion 434, a float sensor 440A, and the like.

[0024] The second sub-tank 431 (container in the present invention) is connected to the first sub-tank 411 via a tank supply path 421. The second sub-tank 431 stores the ink I supplied from the first sub-tank 411. The second sub-tank 431 is also connected to the head module 50 via a head supply path 433. The ink I stored in the second sub-tank 431 is supplied to the head module 50 via the head supply path 433.

[0025] The air pressure pump 432 is connected to the upper part of the second subtank 431, and supplies air to the upper space of the second subtank 431 to control the air present in the upper space to a desired pressure. The head supply path 433 connects the lower part of the second subtank 431 to the head module 50. When the air in the upper space of the second subtank 431 is controlled to a desired pressure, the ink I in the second subtank 431 is pushed out towards the head supply path 433 by the air pressure, and is supplied to the head module 50.

[0026] The temperature control unit 434 is, for example, a heater provided on the outer wall of the second sub-tank 431, and controls the ink I in the second sub-tank 431 to a predetermined temperature at which the ink I does not harden (is difficult to harden).

[0027] The above-mentioned second sub-tank portion 430 is provided with a float sensor 440A that detects the liquid level of the ink I in the second sub-tank 431. The float sensor 440A may also be provided in the first sub-tank portion 410 to detect the liquid level of the ink I in the first sub-tank 411. The float sensor 440A will be described later.

[0028] The head module 50 (image forming section in the present invention) has devices and members necessary for image formation, such as an inkjet head. The head module 50 ejects ink I supplied from the ink supply section 40 (second sub-tank section 430) from the inkjet head to form an image on the recording medium M.

[0029] 1, for the sake of simplicity, the ink supply units 40 and head modules 50 for one color are shown, but the ink supply units 40 and head modules 50 are arranged according to the number of colors to be used. For example, when using four colors, yellow (Y), magenta (M), cyan (C), and black (K), ink supply units 40 and head modules 50 for four colors are arranged.

[0030] As the ink, various inks for inkjet printers can be used. In particular, this embodiment is useful for inks that have the property of being cured by a curing reaction caused by heat, ultraviolet light, or the like. For example, wax, which is a gel component that undergoes a reversible sol-gel phase transition, increases in viscosity and tends to remain, so this embodiment is useful for gel inks (phase transition inks) that contain wax.

[0031] The operation display unit 70 is, for example, a flat panel display such as a liquid crystal display or an organic EL (Electro Luminescence) display with a touch panel. The operation display unit 70 displays an operation menu for the user, information related to image data, various states of the inkjet printer 100, and the like. The operation display unit 70 also includes a plurality of keys and accepts various input operations from the user.

[0032] The input / output interface 80 mediates the transmission and reception of data between the external device 200 and the control unit 90. The input / output interface 80 is configured, for example, by any one of various serial interfaces, various parallel interfaces, or a combination of these.

[0033] The external device 200 is, for example, a personal computer or a facsimile machine, and supplies print jobs, image data, and the like to the control unit 90 via an input / output interface 80 .

[0034] The control unit 90 includes a CPU (Central Processing Unit) 91, a RAM (Random Access Memory) 92, a ROM (Read Only Memory) 93, a storage unit 94, etc.

[0035] The CPU 91 reads out various control programs and setting data stored in the ROM 93, stores them in the RAM 92, and executes the programs to perform various arithmetic processing. For example, the control unit 90 generates a drive signal for an image to be formed based on image data received from the input / output interface 80, and outputs the drive signal to the inkjet head.

[0036] The RAM 92 provides a working memory space for the CPU 91 and stores temporary data. The RAM 92 may include a non-volatile memory.

[0037] The ROM 93 stores various control programs and setting data executed by the CPU 91. Note that, instead of the ROM 93, a rewritable non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used.

[0038] The storage unit 94 stores print jobs and image data related to the print jobs input from the external device 200 via the input / output interface 80. As the storage unit 94, for example, a HDD (Hard Disk Drive) is used, and a DRAM (Dynamic Random Access Memory) or the like may also be used in combination.

[0039] The control unit 90 is connected to the transport unit 10, supply unit 20, discharge unit 30, ink supply unit 40, head module 50, operation display unit 70, input / output interface 80, etc. The control unit 90 comprehensively controls the overall operation of the inkjet printer 100. The transport unit 10, supply unit 20, discharge unit 30, ink supply unit 40, head module 50, operation display unit 70, input / output interface 80, etc. are controlled by the control unit 90 to execute predetermined processes.

[0040] With the above-described configuration, the inkjet printer 100 supplies the recording medium M from the supply section 20 to the conveying section 10, forms an image on the recording medium M conveyed to the conveying section 10 using the head module 50, and conveys the recording medium M with the image formed thereon to the discharge section 30.

[0041] [Float sensor] Fig. 3A is a top view illustrating float sensor 440A. Fig. 3B is a side view illustrating float sensor 440A, showing the case where the liquid level is at the lower limit position. Fig. 3C is a side view illustrating float sensor 440A, showing the case where the liquid level is at the supply stop position. Fig. 3D is a side view illustrating float sensor 440A, showing the case where the liquid level is at the upper limit position. Figs. 3B to 3D show the inside of second sub-tank 431.

[0042] 1, a float sensor 440A is provided in the second sub-tank portion 430 of the ink supply portion 40. As shown in FIGS. 3A to 3D, the float sensor 440A has a float 441, a magnet 442, a shaft portion 443, an upper limit reed switch 444, a lower limit reed switch 445, an upper limit stopper 446, a lower limit stopper 447, and the like.

[0043] Float 441 is a float that floats on the surface of ink I and is movable according to the level of the surface of ink I. In plan view, a through hole into which shaft 443 is inserted is formed in the center of float 441. Furthermore, magnet 442, which is a permanent magnet, is disposed inside float 441.

[0044] The shaft portion 443 (support portion in the present invention) is a rod-shaped member whose end is supported on the top plate 431a side of the second sub-tank 431 and which extends downward along the vertical direction. The shaft portion 443 is inserted into the through-hole of the float 441. The shaft portion 443 supports the float 441 so that it can move up and down (move up and down) along the shaft portion 443, that is, along the vertical direction. Therefore, the float 441 moves up and down along the shaft portion 443 in accordance with the up and down movement of the liquid level of the ink I.

[0045] In addition, the shaft portion 443 may be a rod-shaped member whose end is supported on the bottom plate side of the second sub-tank 431 and extends vertically upward, as long as it can guide the float 441 so as to be able to move up and down.

[0046] The upper limit reed switch 444 and the lower limit reed switch 445 are electromechanical switches that are operated by magnetic force. The upper limit reed switch 444 and the lower limit reed switch 445 are disposed on the inside of the shaft portion 443, for example.

[0047] When magnet 442 approaches upper limit reed switch 444 together with float 441, an internal switch of upper limit reed switch 444 (detection unit in the present invention) is turned on by the magnetic force of magnet 442. When magnet 442 moves away from upper limit reed switch 444 together with float 441, the magnetic force of magnet 442 weakens, and the internal switch of upper limit reed switch 444 is turned off.

[0048] Similarly, when magnet 442 approaches lower limit reed switch 445 together with float 441, an internal switch of lower limit reed switch 445 (detection unit in the present invention) is turned on by the magnetic force of magnet 442. When magnet 442 moves away from lower limit reed switch 445 together with float 441, the magnetic force of magnet 442 weakens, and the internal switch of lower limit reed switch 445 is turned off.

[0049] The upper limit reed switch 444 is disposed at a position where an internal switch is turned on when the float 441, which rises together with the liquid level of the ink I, is restricted from moving upward by an upper limit stopper 446, which will be described later. The liquid level position at this time becomes the upper limit in the second subtank 431. In other words, the upper limit reed switch 444 is disposed so as to detect the float 441 at the upper limit liquid level position UL. Therefore, when the liquid level of the ink I rises in the second subtank 431 and reaches the upper limit, the upper limit reed switch 444 is turned on, and the supply of ink I to the second subtank 431 is stopped.

[0050] Furthermore, the lower limit reed switch 445 is disposed at a position where the internal switch is turned on when the float 441, which descends together with the liquid level of the ink I, is restricted from moving downward by a lower limit stopper 447, which will be described later. The liquid level position at this time becomes the lower limit in the second subtank 431. In other words, the lower limit reed switch 445 is disposed so as to detect the float 441 at the lower limit liquid level position LL. Therefore, when the liquid level of the ink I in the second subtank 431 descends and reaches the lower limit, the lower limit reed switch 445 is turned on, and the supply of ink I to the second subtank 431 begins.

[0051] The upper limit stopper 446 is an upper limit stopper that restricts the upward movement of the float 441, and defines the upper limit position of the float 441. The upper limit stopper 446 is arranged on the outer circumferential surface of the shaft portion 443 so as to come into contact with the upper surface of the float 441 and restrict the upward movement of the float 441.

[0052] The lower limit stopper 447 is a lower limit stopper that restricts the downward movement of the float 441, and defines the lower limit position of the float 441. The lower limit stopper 447 is disposed on the outer circumferential surface of the shaft portion 443 so as to come into contact with the lower surface of the float 441 and restrict the downward movement of the float 441.

[0053] With the above-described configuration, float 441 moves up and down along shaft 443 in accordance with the up and down movement of the liquid level of ink I. Then, float sensor 440A detects whether the liquid level of ink I is at the upper limit or not depending on whether upper limit reed switch 444 is turned on by magnet 442 inside float 441. Similarly, float sensor 440A detects whether the liquid level of ink I is at the lower limit or not depending on whether lower limit reed switch 445 is turned on by magnet 442 inside float 441.

[0054] In this manner, the float sensor 440A detects the liquid level (upper and lower limits) of the ink I.

[0055] Here, the shaft portion 443 around the lower limit reed switch 445 is immersed in the ink I for a long time, and the ink I around the shaft portion 443 is replaced, for example, when ink I is supplied to the second sub-tank 431 or when ink I is supplied to the head module 50. Therefore, ink I is unlikely to accumulate between the shaft portion 443 and the float 441, and adhesion is unlikely to occur or does not occur.

[0056] On the other hand, the shaft 443 around the upper limit reed switch 444 is immersed in the ink I when the level of the ink I rises to the upper limit, but the rest is exposed to air. Therefore, the ink I is likely to accumulate between the shaft 443 and the float 441, which can easily cause solidification. Also, around the upper limit reed switch 444, the ink I is likely to accumulate between the upper limit stopper 446 and the float 441, which can easily cause solidification. When the ink I solidifies in this way, the float 441 cannot move, and the liquid level detection does not function properly. When the ink has the property of being cured by a curing reaction caused by heat, ultraviolet light, or the like, such problems are likely to occur.

[0057] Therefore, in this embodiment, float sensor 440A includes tank supply path 421 that supplies ink I so that it flows between float 441 and shaft portion 443.

[0058] Tank supply path 421 (first supply section in the present invention) is provided so as to penetrate top plate 431a of second sub-tank 431. A supply port of tank supply path 421 is arranged so as to supply ink I from above shaft portion 443 along the outer circumferential surface of shaft portion 443. Thus, in float sensor 440A, tank supply path 421 is configured so as to supply ink I from above shaft portion 443.

[0059] The supply port of the tank supply path 421 is positioned so as to supply the ink I from above the shaft portion 443, but is not limited to this position, and may be positioned so as to supply the ink I at least from above the float 441 at the upper limit liquid level position UL.

[0060] In addition, the upper limit stopper 446 and the lower limit stopper 447 described above are also configured so as not to impede the ink I flowing downward from the tank supply path 421 along the outer circumferential surface of the shaft portion 443 .

[0061] For example, assume that the upper limit stopper 446 and the lower limit stopper 447 are formed of annular members extending radially outward from the outer circumferential surface of the shaft portion 443. In this case, through holes (not shown) are provided inside the upper limit stopper 446 and the lower limit stopper 447, i.e., on the shaft portion 443 side. The through holes provided in the upper limit stopper 446 and the lower limit stopper 447 allow the ink I supplied from the tank supply path 421 to flow downward along the shaft portion 443.

[0062] Also, for example, assume that the upper limit stopper 446 and the lower limit stopper 447 are composed of a plurality of rod-shaped members extending radially outward from the outer circumferential surface of the shaft portion 443. In this case, the ink I supplied from the tank supply path 421 passes between the rod-shaped members and flows downward along the shaft portion 443.

[0063] Furthermore, the float sensor 440A may be configured to include a tank supply path 425 (second supply section in the present invention) connected to the lower part of the second sub-tank 431, in addition to the tank supply path 421 connected to the upper part of the second sub-tank 431.

[0064] The supply port of the tank supply path 425 may be positioned so as to supply ink I at least from below the upper limit liquid level position UL, but may also be connected to the second sub-tank 431 at a position below the lower limit liquid level position LL so that the supply port is always below the liquid level of ink I.

[0065] When ink I is supplied from tank supply path 425, which is located below the liquid level, a flow occurs in the ink I in second sub-tank 431. This makes it possible to agitate the components that make up ink I, stabilizing the components of ink I and preventing ink I from hardening in second sub-tank 431.

[0066] Although not shown, the tank supply path 425 has, for example, a pump, a valve, etc., and is configured to be able to branch off from the tank supply path 421 and supply the ink I into the second subtank 431. For example, the upstream side of the tank supply path 425 may be connected to the tank supply path 421 between the degassing module 422 and the pump 423, and may be configured to branch off from the tank supply path 421.

[0067] The tank supply path 421 may also have a heating unit 426 (see FIG. 1). For example, the heating unit 426 is provided on the second sub-tank 431 side of the tank supply path 421. The heating unit 426 heats the ink I flowing through the tank supply path 421, so that ink I having a higher temperature than the ink I supplied from the tank supply path 425 is supplied from the tank supply path 421. This allows, for example, solidified ink I to be melted by the high-temperature ink I and returned to a liquid state.

[0068] Here, liquid level detection by float sensor 440A and supply control of ink I will be described with reference to FIGS. 3B to 3D.

[0069] When the head module 50 ejects the ink I supplied from the second sub-tank 431 from the inkjet head to form an image on the recording medium M, the ink I in the second sub-tank 431 decreases and the liquid level of the ink I drops.

[0070] 3B, when float 441 descends until it contacts lower limit stopper 447, lower limit reed switch 445 turns on due to the magnetic force of magnet 442 in float 441.

[0071] When the lower limit reed switch 445 is turned on, the control unit 90 controls the liquid sending unit 420 (the pump 423, the valve 424, etc.) to start supplying the ink I from the tank supply path 421 to the second sub-tank 431.

[0072] At this time, the ink I supplied from the tank supply path 421 flows from above the shaft portion 443 along the outer circumferential surface of the shaft portion 443. This prevents the ink I from accumulating between the float 441 and the shaft portion 443 or around the upper limit stopper 446, and prevents the ink I from solidifying.

[0073] At this time, the control unit 90 may supply the ink I from the tank supply path 425 to the second sub-tank 431. The ink I supplied from the tank supply path 425 causes a flow of the ink I in the second sub-tank 431, making it possible to agitate the components constituting the ink I and stabilize the components of the ink I, thereby preventing the ink I from hardening in the second sub-tank 431.

[0074] As the ink I is supplied from the tank supply path 421 (or the tank supply path 421 and the tank supply path 425) to the second sub-tank 431, the liquid level of the ink I rises, and as the liquid level of the ink I rises, the float 441 also rises.

[0075] Then, when a predetermined time has elapsed since the start of the supply of ink I, the control unit 90 stops the supply of ink I. At this time, the control unit 90 stops the supply of ink I when the float 441 is a predetermined distance away from the upper limit stopper 446, as shown in FIG.

[0076] In this way, by stopping the supply of ink I when float 441 is a predetermined distance away from upper limit stopper 446, unless there is some malfunction, float 441 will not come into contact with upper limit stopper 446. Therefore, it is possible to avoid a state in which ink I is likely to accumulate and solidify, that is, a state in which float 441 comes into contact with upper limit stopper 446.

[0077] If some malfunction occurs and the supply of ink I to the second sub-tank 431 is not stopped, the liquid level of ink I will rise further, and as the liquid level of ink I rises, the float 441 will rise.

[0078] Then, as shown in FIG. 3D, when float 441 rises until it comes into contact with upper limit stopper 446, upper limit reed switch 444 turns on due to the magnetic force of magnet 442 inside float 441.

[0079] When the upper limit reed switch 444 is turned on, the control unit 90 controls the liquid delivery unit 420 (pump 423, valve 424, etc.) to stop the supply of ink I from the tank supply path 421 to the second subtank 431, and displays an error message on the operation display unit 70. In this way, the upper limit reed switch 444 detects the upper limit of the liquid level when a malfunction occurs.

[0080] The control unit 90 is not limited to the above-described supply control of the ink I, and may also perform the following control: For example, when a first predetermined time has elapsed since the ink I was last supplied to the second sub-tank 431, the ink I is supplied from the tank supply path 421 to the second sub-tank 431 at a predetermined flow rate or more for a second predetermined time.

[0081] The first predetermined time is set, for example, to a time shorter than the time it takes for the ink I to start to solidify. The second predetermined time and predetermined flow rate are set, for example, to a time and flow rate that allows the solidified ink I to be washed away with new ink I and returned to a liquid state, on the premise that the liquid level of the ink I does not exceed an upper limit.

[0082] As described above, in this embodiment, the inkjet printer 100 includes the float sensor 440A. The float sensor 440A includes the tank supply path 421 that supplies the ink I so that it flows between the float 441 and the shaft portion 443.

[0083] According to this embodiment configured as described above, the ink I supplied from the tank supply path 421 flows downward along the shaft portion 443, which prevents the ink I from accumulating between the float 441 and the shaft portion 443 and prevents the ink I from solidifying. As a result, malfunction of the float 441 caused by the solidification of the ink I is prevented, and the liquid level can be detected normally.

[0084] <Variation 1> 4A to 4C are diagrams illustrating float sensor 440B, which is a modified example of float sensor 440A shown in Figs. 3A to 3D. Fig. 4A is a side view illustrating float sensor 440B, showing the case where the liquid level is at the lower limit position. Fig. 4B is a side view illustrating float sensor 440B, showing the case where the liquid level is at the supply stop position. Fig. 4C is a side view illustrating float sensor 440B, showing the case where the liquid level is at the upper limit position. Figs. 4A to 4C show the inside of second sub-tank 431.

[0085] Float sensor 440B is basically the same in configuration as float sensor 440A. Therefore, in Figures 4A to 4C, the same reference numerals are used for the same components as float sensor 440A, but as described below, the reference numeral "a" is attached to the upper limit detection side, and the reference numeral "b" is attached to the lower limit detection side.

[0086] In the above embodiment, float sensor 440A detects the upper and lower limits of the liquid level using one float 441. On the other hand, in this modification, float sensor 440B uses two floats (upper limit float 441a and lower limit float 441b), with upper limit float 441a detecting the upper limit of the liquid level and lower limit float 441b detecting the lower limit of the liquid level.

[0087] The float sensor 440B has an upper limit float 441a and a lower limit float 441b, and therefore magnets 442a and 442b are disposed on the upper limit float 441a and the lower limit float 441b, respectively.

[0088] An upper limit reed switch 444, an upper limit stopper 446a, and an upper limit stopper 447a are provided for the upper limit float 441a.

[0089] Further, a lower limit reed switch 445, a lower stage upper limit stopper 446b, and a lower stage lower limit stopper 447b are provided for a lower limit float 441b arranged below the upper limit float 441a.

[0090] The lower-stage upper limit stopper 446b and the upper-stage lower limit stopper 447a are arranged apart from each other so that the magnet 442a of the upper limit float 441a and the magnet 442b of the lower limit float 441b do not affect each other. Therefore, the lower-stage upper limit stopper 446b is arranged further away from the upper-stage upper limit stopper 446a.

[0091] In this manner, the float sensor 440B is configured to have a so-called upper limit detection float sensor and a lower limit detection float sensor.

[0092] In addition, in this modification, a supply stop reed switch 448 is disposed on the side of the lower limit float 441b.

[0093] The reed switch 448 for stopping supply is disposed at a position where the internal switch is turned on when the lower limit float 441b, which rises together with the level of the ink I, is restricted from moving upward by the lower upper limit stopper 446b. The position of the liquid level at this time is the position where the supply of the ink I is stopped, and the reed switch 448 for stopping supply is disposed so as to detect the float 441 at the liquid level position SL where the supply of the ink I is stopped. Therefore, when the level of the ink I rises in the second subtank 431 and the reed switch 448 for stopping supply is turned on, the supply of ink I to the second subtank 431 is stopped.

[0094] In this modification, the float sensor 440B includes the tank supply path 421 described above, and supplies ink I to flow between the upper limit float 441a and the lower limit float 441b and the shaft portion 443. In this modification, the tank supply path 421 may also include the heating portion 426 described above (see FIG. 1).

[0095] Also in this modified example, the float sensor 440B includes the tank supply path 425 described above, and supplies the ink I from the tank supply path 425 that is located below the liquid surface.

[0096] In this modification, the upper-stage upper limit stopper 446a, the upper-stage lower limit stopper 447a, the lower-stage upper limit stopper 446b, and the lower-stage lower limit stopper 447b have the same configuration as the above-described upper limit stopper 446 and lower limit stopper 447. That is, the upper-stage upper limit stopper 446a, the upper-stage lower limit stopper 447a, the lower-stage upper limit stopper 446b, and the lower-stage lower limit stopper 447b are also configured so as not to impede the ink I flowing downward from the tank supply path 421 along the outer circumferential surface of the shaft portion 443.

[0097] Here, liquid level detection by float sensor 440B and supply control of ink I will be described with reference to FIGS. 4A to 4C.

[0098] When the head module 50 ejects the ink I supplied from the second sub-tank 431 from the inkjet head to form an image on the recording medium M, the ink I in the second sub-tank 431 decreases and the liquid level of the ink I drops.

[0099] 4A, when the lower limit float 441b descends until it contacts the lower limit stopper 447b on the lower stage side, the lower limit reed switch 445 is turned on by the magnetic force of the magnet 442b in the lower limit float 441b.

[0100] When the lower limit reed switch 445 is turned on, the control unit 90 controls the liquid sending unit 420 (the pump 423, the valve 424, etc.) to start supplying the ink I from the tank supply path 421 to the second sub-tank 431.

[0101] At this time, the ink I supplied from the tank supply path 421 flows from above the shaft portion 443 along the outer circumferential surface of the shaft portion 443. This prevents the ink I from accumulating between the upper limit float 441a and the shaft portion 443 and between the lower limit float 441b and the shaft portion 443, or around the upper upper limit stopper 446a, the upper lower limit stopper 447a, and the lower upper limit stopper 446b, and prevents the ink I from solidifying.

[0102] At this time, the control unit 90 may supply the ink I from the tank supply path 425 to the second sub-tank 431. The ink I supplied from the tank supply path 425 causes a flow of the ink I in the second sub-tank 431, making it possible to agitate the components constituting the ink I and stabilize the components of the ink I, thereby preventing the ink I from hardening in the second sub-tank 431.

[0103] As the ink I is supplied from the tank supply path 421 (or the tank supply path 421 and the tank supply path 425) to the second sub-tank 431, the liquid level of the ink I rises, and as the liquid level of the ink I rises, the lower limit float 441b also rises.

[0104] Then, as shown in FIG. 4B, when the lower limit float 441b rises until it comes into contact with the lower-stage upper limit stopper 446b, the magnetic force of the magnet 442b in the lower limit float 441b turns on the supply stop reed switch 448.

[0105] When the supply stop reed switch 448 is turned on, the control unit 90 controls the liquid sending unit 420 (the pump 423, the valve 424, etc.) to stop the supply of the ink I from the tank supply path 421 to the second sub-tank 431.

[0106] The lower upper limit stopper 446b is disposed at a position away from the upper upper limit stopper 446a and the upper lower limit stopper 447a. Therefore, the upper limit float 441a stops the supply of ink I when it is in contact with the upper lower limit stopper 447a and is a predetermined distance away from the upper upper limit stopper 446a. As a result, unless there is some malfunction, the upper limit float 441a will not come into contact with the upper upper limit stopper 446a. Therefore, it is possible to avoid a state in which the ink I is likely to accumulate and solidify, that is, a state in which the upper limit float 441a comes into contact with the upper upper limit stopper 446a.

[0107] If some malfunction occurs and the supply of ink I to the second sub-tank 431 does not stop, the ink I level will rise further, and as the ink I level rises, the upper limit float 441a will rise.

[0108] Then, as shown in FIG. 4C, when the upper limit float 441a rises until it contacts the upper limit stopper 446a on the upper stage side, the upper limit reed switch 444 is turned on by the magnetic force of the magnet 442a in the upper limit float 441a.

[0109] When the upper limit reed switch 444 is turned on, the control unit 90 controls the liquid delivery unit 420 (pump 423, valve 424, etc.) to stop the supply of ink I from the tank supply path 421 to the second subtank 431, and displays an error message on the operation display unit 70. In this way, the upper limit reed switch 444 detects the upper limit of the liquid level when a malfunction occurs.

[0110] In addition, even in this modified example, if a first predetermined time has elapsed since the last time ink I was supplied to the second sub-tank 431, the control unit 90 may supply ink I from the tank supply path 421 to the second sub-tank 431 at a predetermined flow rate or more for a second predetermined time.

[0111] As described above, in this modified example, float sensor 440B includes tank supply path 421, and therefore, similarly to the above embodiment, it is possible to prevent ink I from stagnating and to prevent adhesion of ink I. As a result, malfunction of float 441 caused by adhesion of ink I is prevented, and liquid level detection can be performed normally.

[0112] <Variation 2> Figures 5A and 5B are diagrams illustrating float sensor 440C, which is a modified example of float sensor 440B shown in Figures 4A to 4C. Figure 5A is a top view illustrating float sensor 440C. Figure 5B is a side view illustrating float sensor 440C, showing the case where the liquid level is at the lower limit position. Figure 5B illustrates the inside of second sub-tank 431.

[0113] Float sensor 440C has the same configuration as float sensor 440B, with some exceptions, and therefore in Figures 5A and 5B, the same components as float sensor 440B are given the same reference numerals, and hereinafter, overlapping descriptions will be omitted.

[0114] In float sensor 440A and float sensor 440B, the supply port of tank supply path 421 is arranged above shaft portion 443 so as to supply ink I from a part of the outer circumferential surface of shaft portion 443, as shown in FIGS. 3A to 4C.

[0115] In contrast, in float sensor 440C, tank supply passage 421 has supply port 427 that surrounds the entire outer periphery of shaft portion 443 at the upper portion of shaft portion 443, as shown in FIGS. 5A and 5B.

[0116] Supply port 427 supplies ink I from above shaft portion 443 and along the entire outer periphery of shaft portion 443, thereby preventing ink I from accumulating between float 441 and the entire outer periphery of shaft portion 443 and preventing adhesion of ink I. As a result, malfunction of float 441 due to adhesion of ink I is prevented, and the liquid level can be detected normally.

[0117] <Modification 3> Figures 6A and 6B are diagrams illustrating float sensor 440D, which is a modified example of float sensor 440C shown in Figures 5A and 5B. Figure 6A is a top view illustrating float sensor 440D. Figure 6B is a side view illustrating float sensor 440D, showing the case where the liquid level is at the lower limit position. Figure 6B illustrates the inside of second sub-tank 431.

[0118] Float sensor 440D has the same configuration as float sensor 440C, with some exceptions, and therefore in Figures 6A and 6B, the same components as float sensor 440C are given the same reference numerals, and hereinafter, overlapping descriptions will be omitted.

[0119] In the float sensor 440C shown in FIGS. 5A and 5B, the tank supply passage 421 is provided so as to penetrate the top plate 431a of the second sub-tank 431.

[0120] In contrast, in this modified example, in the float sensor 440D, the tank supply path 421 is provided so as to penetrate the side wall 431b of the second sub-tank 431, extends along the inner wall of the top plate 431a, and is connected to the supply port 427.

[0121] With the above configuration, in this modification as well, ink I is supplied from the entire outer periphery of shaft portion 443 through supply port 427, which prevents ink I from accumulating between float 441 and the entire outer periphery of shaft portion 443 and prevents adhesion of ink I. As a result, malfunction of float 441 due to adhesion of ink I is prevented, and the liquid level can be detected normally.

[0122] <Variation 4> Fig. 7A is a top view illustrating float sensor 460, which is a modified example of float sensor 440A shown in Figs. 3A to 3D. Fig. 7B is a side view illustrating float sensor 460, showing the case where the liquid level is at the lower limit position. Fig. 7C is a side view illustrating float sensor 460, showing the case where the liquid level is at the upper limit position. Figs. 7B and 7C show the interior of second sub-tank 431.

[0123] Although float sensor 460 has a different configuration from float sensor 440A, tank supply passages 421, 425, etc. may have the same configuration as float sensor 440A. Therefore, in Figures 7A to 7C, the same reference numerals are used for the same configuration as float sensor 440A, including second sub-tank 431, etc.

[0124] In this modification, as shown in FIGS. 7A to 7C, a float sensor 460 includes a float 461, a shaft portion 462, an upper limit optical sensor 463, a lower limit optical sensor 464, and the like.

[0125] The float 461 is a floating body that floats on the surface of the ink I and can move according to the position of the ink I surface. The float 461 is supported rotatably around the axis of the shaft portion 462 that extends horizontally, and rotates vertically according to the position of the ink I surface.

[0126] The shaft portion 462 is a rod-shaped member attached to the side wall 431b of the second sub-tank 431 and extending horizontally from the side wall 431b. As described above, the shaft portion 462 supports the float 461 rotatably around its axis.

[0127] The upper limit optical sensor 463 and the lower limit optical sensor 464 are sensors that are disposed outside the second subtank 431 and optically detect the float 461 from outside the second subtank 431. In this case, as the second subtank 431, a container made of a material that transmits the wavelength of light used by the upper limit optical sensor 463 and the lower limit optical sensor 464 is used.

[0128] 7C, the upper limit optical sensor 463 (detection unit in the present invention) is disposed so as to detect the float 461 at the upper limit liquid level position UL. Therefore, when the liquid level of the ink I in the second subtank 431 rises and reaches the upper limit, the upper limit optical sensor 463 detects the float 461 and stops the supply of ink I to the second subtank 431.

[0129] 7B, the lower limit optical sensor 464 (detection unit in the present invention) is disposed so as to detect the float 461 at the lower limit liquid level position LL. Therefore, when the liquid level of the ink I in the second subtank 431 drops and reaches the lower limit, the lower limit optical sensor 464 detects the float 461 and starts supplying the ink I to the second subtank 431.

[0130] In this modified example, the tank supply path 421 is disposed so as to supply the ink I to the gap between the float 461 and the shaft portion 462 from above.

[0131] Since tank supply path 421 is disposed so as to supply ink I from above to the gap between float 461 and shaft portion 462, ink I supplied from tank supply path 421 flows including through the gap between float 461 and shaft portion 462. This prevents ink I from accumulating between float 461 and shaft portion 462, and prevents ink I from solidifying.

[0132] At this time, the control unit 90 may supply the ink I from the tank supply path 425 to the second sub-tank 431. The ink I supplied from the tank supply path 425 causes a flow of the ink I in the second sub-tank 431, making it possible to agitate the components constituting the ink I and stabilize the components of the ink I, thereby preventing the ink I from hardening in the second sub-tank 431.

[0133] As described above, in this modified example, the float sensor 460 also includes the tank supply path 421 that supplies the ink I so that it flows between the float 461 and the shaft portion 462.

[0134] According to this modified example configured in this manner, the ink I supplied from the tank supply path 421 flows including through the gap between the float 461 and the shaft 462, preventing the ink I from accumulating between the float 441 and the shaft 443 and preventing the ink I from solidifying. As a result, malfunction of the float 441 due to solidification of the ink I is prevented, and the liquid level can be detected normally.

[0135] The above-mentioned embodiments and modifications are merely examples of the embodiment of the present invention, and the technical scope of the present invention should not be interpreted as being limited by them. In other words, the present invention can be embodied in various forms without departing from the gist or main characteristics of the present invention.

[0136] For example, float sensors 440A-440D in the above-described embodiment and modified examples are configured such that shaft portion 443 guides float 441 (upper limit float 441a, lower limit float 441b) to be movable up and down. Alternatively, shaft portion 443 may be configured to allow float 441 (upper limit float 441a, lower limit float 441b) to slide up and down. [Explanation of symbols]

[0137] 10. Conveyor 20 Supply section 30 Discharge section 40 Ink supply unit 50 Head Module 70 Operation display section 80 Input / Output Interface 90 Control section 100 Inkjet Printer 200 External device 410 1st Subtank Section 411 First Subtank 420 Liquid delivery section 421, 425 Tank supply line 422 Degassing Module 423 Pump 424 Valve 426 Heating section 427 Supply Inlet 430 Second Subtank Section 431 Second Subtank 432 Pneumatic Pump 433 Head supply channel 434 Temperature control unit 440A, 440B, 440C, 440D, 460 Float Sensor 441 Float 441a Upper Float 441b Lower limit float 442, 442a, 442b Magnets 443 Shaft 444 Upper limit reed switch 444a Upper limit reed switch 444b Lower Upper Limit Reed Switch 445 Lower Limit Reed Switch 445a Upper limit reed switch 445b Lower limit reed switch 446 Upper limit stopper 446a Upper limit stopper 446b Lower upper limit stopper 447 Lower limit stopper 447a Upper limit stopper 447b Lower limit stopper 448 Supply stop reed switch 461 Float 462 Shaft 463 Upper limit optical sensor 464 Lower Limit Optical Sensor

Claims

1. a float supported by a support so as to move in response to a liquid level of the ink in the container; A detection unit that detects the float at a predetermined liquid level position; a first supply section that supplies the ink to flow between the support section and the float; Equipped with Float sensor.

2. The support portion is a shaft portion along a vertical direction, and supports the float movably along the shaft portion.

2. The float sensor according to claim 1.

3. The detection units are arranged to detect the float at upper and lower limit liquid level positions, the first supply unit is disposed to supply the ink from above the float when the ink level is at the upper limit of the ink level; 3. The float sensor according to claim 2.

4. The support portion is a shaft portion along a horizontal direction, and supports the float rotatably around the shaft portion.

2. The float sensor according to claim 1.

5. a second supply unit that supplies the ink below an upper limit liquid level position; 2. The float sensor according to claim 1.

6. The container is provided with a temperature control unit that controls the ink to a predetermined temperature.

2. The float sensor according to claim 1.

7. The ink is a gel ink containing wax.

2. The float sensor according to claim 1.

8. The shaft portion has stoppers that respectively define an upper limit position and a lower limit position of the float.

3. The float sensor according to claim 2.

9. the first supply unit supplies the ink for a second predetermined time when a first predetermined time has elapsed since the previous supply of the ink; 2. The float sensor according to claim 1.

10. The first supply unit supplies the ink at a flow rate equal to or greater than a predetermined flow rate.

2. The float sensor according to claim 1.

11. the first supply unit has a heating unit that heats the ink so as to supply the ink at a temperature higher than a temperature of the ink supplied from the second supply unit; 6. The float sensor according to claim 5.

12. the first supply portion has a supply port surrounding an entire outer circumferential surface of the shaft portion and supplying the ink from above the shaft portion; 3. The float sensor according to claim 2.

13. A container for storing ink; an image forming unit that forms an image using the ink supplied from the container; A float sensor according to any one of claims 1 to 12; Equipped with Image forming device.

Images