Ink heating device, ink supply device, and image forming system

Abstract

The ink heating device (7) has a heater circuit (91), a relay (5) and a control unit (4). The heater circuit (91) has a heater (71) that heats the ink and an automatic reset bimetallic switch (92) that is located between the heater (71) and the AC power supply (A). The relay (5) is located between the bimetallic switch (92) and the AC power supply (A). The control unit (4) disconnects and connects the relay (5) according to the state of the heater circuit (91).

Description

Technical Field

[0001] The present invention relates to an ink heating device for heating ink supplied to an inkjet recording device, an ink supply device having the ink heating device, and an image forming system having the ink supply device and the inkjet recording device. Background Technology

[0002] In inkjet recording devices, although ink cartridges are installed to supply ink to the recording head, ink supply devices with large-capacity ink cartridges are provided as an option, taking into account the large amount of ink consumption.

[0003] To achieve good image quality, the viscosity of the ink needs to be maintained within an appropriate range; however, sometimes the viscosity of the ink increases due to low room temperature. Therefore, a mechanism for heating the ink is provided in the ink supply device. As an example of a mechanism for heating the ink, a heater unit with piping and a heater is known. One end of the piping is connected to a high-capacity ink cartridge, and the other end is connected to the ink supply path of the inkjet recording device. The ink delivered from the ink cartridge is heated by the heater and then supplied to the inkjet recording device.

[0004] However, since image formation cannot begin until the ink is heated to the appropriate temperature, a waiting time occurs. Therefore, a system for rapidly heating the ink has been provided to shorten this waiting time. However, due to the use of a large current in rapid heating, overheating may occur. Therefore, techniques to prevent overheating have been investigated in the prior art.

[0005] For example, Patent Document 1 proposes the following solution: It includes a first detection mechanism and a second detection mechanism, and forcibly shuts off the power supply to the heater based on the detection of the second detection mechanism. The first detection mechanism detects a situation where the heater control signal is off and the heater status signal is on for a first set time or more. If, after being detected by the first detection mechanism, the second detection mechanism detects again a situation where the heater control signal is off and the heater status signal is on after a second set time, it detects an anomaly. Furthermore, Patent Document 2 proposes the following solution: It detects whether the voltage change rate of the AC power supply during zero-crossing timing is above an allowable value; if the voltage change rate is above the allowable value, it prohibits power from the AC power supply to the heating element.

[0006] [Existing Technical Documents]

[0007] [Patent Literature]

[0008] Patent Document 1: Japanese Patent Publication No. 2001-191539; Patent Document 2: Japanese Patent Publication No. 2011-113807 Summary of the Invention

[0009] [The technical problem the invention aims to solve]

[0010] However, in the structures proposed in Patent Documents 1 and 2, since the control unit uses information output from the device to determine the device's abnormality and stops heating when an abnormality is determined, a time difference is generated from the occurrence of overheating to the cessation of heating, making it impossible to stop heating immediately in the event of overheating.

[0011] In view of the above, the object of the present invention is to provide an ink heating device, an ink supply device, and an image forming system that can shorten the time from the occurrence of overheating to the cessation of heating.

[0012] [Technical solutions used to solve technical problems]

[0013] To solve the above-mentioned technical problems, the ink heating device of the present invention is characterized by having a heater circuit, a relay, and a control unit, wherein the heater circuit has: a heater for heating ink; and an automatic reset bimetallic switch disposed between the heater and a power source, the relay being disposed between the bimetallic switch and the power source, and the control unit causing the relay to open and close according to the state of the heater circuit.

[0014] Furthermore, the ink supply device according to the present invention is characterized in that it has an ink cartridge and any one of the ink heating devices, wherein the ink cartridge contains the ink, and the ink heating device heats the ink delivered from the ink cartridge.

[0015] Furthermore, the image forming system of the present invention is characterized by having the ink supply device and the inkjet recording device, wherein the inkjet recording device comprises: a transport unit that transports a sheet-like recording medium; and an inkjet head that ejects the ink supplied from the ink supply device onto the recording medium transported by the transport unit.

[0016] [Invention Effects]

[0017] According to the present invention, the time from the occurrence of overheating to the cessation of heating can be shortened. Attached Figure Description

[0018] Figure 1 This is a perspective view showing the appearance of a printer and ink supply device according to an embodiment of the present invention.

[0019] Figure 2 This is a schematic front view illustrating the internal structure of a printer according to an embodiment of the present invention.

[0020] Figure 3 This is a diagram schematically illustrating the ink supply path according to one embodiment of the present invention.

[0021] Figure 4 This is a perspective view showing the interior of an ink supply device according to an embodiment of the present invention.

[0022] Figure 5 This is a schematic cross-sectional view of a heater unit according to an embodiment of the present invention.

[0023] Figure 6A This is a perspective view of a heater according to one embodiment of the present invention.

[0024] Figure 6B This is a perspective view of the piping involved in one embodiment of the present invention.

[0025] Figure 7 This is a circuit diagram of an ink heating device according to one embodiment of the present invention.

[0026] Figure 8 This is a circuit diagram of a heater circuit according to one embodiment of the present invention.

[0027] Figure 9 This is a timing diagram of the detection signal according to one embodiment of the present invention.

[0028] Figure 10 This is a flowchart illustrating the operation of an ink heating device according to an embodiment of the present invention. Detailed Implementation

[0029] Below, refer to the appendix. Figure 1 The image forming system 3 according to one embodiment of the present invention will be described below.

[0030] First, the overall structure of the image forming system 3 will be described. The image forming system 3 includes an ink supply device 2 and a printer 1 (an example of an inkjet recording device). Figure 1 This is a perspective view showing the appearance of the ink supply device 2 and the printer 1. Figure 2 This is a schematic front view showing the internal structure of printer 1. Figure 3 This is a diagram schematically showing the ink supply path. Below, we will... Figure 1 Fr side in Figure 2The front side of the paper (near the front) is used as the front side (front side) of the ink supply device 2 and the printer 1. The left and right orientations are explained based on the direction of viewing the ink supply device 2 and the printer 1 from the front. In each figure, U, Lo, L, R, Fr, and Rr represent up, down, left, right, front, and back, respectively.

[0031] Printer 1 is an inkjet image forming apparatus that forms images by ejecting ink onto a sheet S (an example of a sheet-shaped recording medium) such as plain paper or coated paper. An ink supply unit 2 is located at the rear of printer 1 and supplies ink to printer 1.

[0032] Printer 1 has a box-shaped main body housing 10 that houses various devices. A pull-out paper tray 15 for holding sheet material S is located in the lower part of the main body housing 10. A manual paper feed tray 25 for manually loading sheet material S is located on the right side of the main body housing 10. Above the manual paper feed tray 25 is a paper discharge tray 17 for loading sheet material S with completed image formation. An outlet 19 is formed in the upper part of the left side of the main body housing 10, which is used to feed sheet material S to a post-processing unit (not shown) adjacent to the left side of printer 1.

[0033] A recording head unit 34Y, 34Bk, 34C, and 34M (collectively referred to as recording head unit 34) is disposed in the central part of the main body casing 10. Each recording head unit 34Y, 34Bk, 34C, and 34M has one or more inkjet heads that eject ink to the sheet S, respectively ejecting yellow, black, cyan, and magenta inks. Below the recording head unit 34 is a conveying unit 40, which conveys the sheet S with the image formed onto a conveyor belt 45. To the left of the conveying unit 40 is a drying unit 48, which dries the sheet S while conveying it after image formation. An ink cartridge 51 filled with ink is housed in the lower left part of the main body casing 10.

[0034] That is, the recording device in this embodiment is a so-called line printer. As another embodiment, there is a so-called serial printer, which alternately performs scanning of a carriage carrying an inkjet head relative to a recording medium and transport of the recording medium in a direction intersecting the scanning direction.

[0035] To the right of the conveying unit 40, there is a first conveying path 21 from the paper feed tray 15 to the conveying unit 40, and a manual conveying path 27 that merges from the manual paper feed tray 25 to the first conveying path 21. To the left of the drying unit 48, there is a second conveying path 22 from the drying unit 48 to the discharge port 19. Above the recording head unit 34, there are a third conveying path 23 and a fourth conveying path 24, wherein the third conveying path 23 branches from the second conveying path 22 and reaches the discharge tray 17, and the fourth conveying path 24 branches from the third conveying path 23 and merges with the first conveying path 21. At the branch points of the second conveying path 22 and the third conveying path 23, and at the branch points of the third conveying path 23 and the fourth conveying path 24, there are guide components (not shown) for guiding the conveying of the sheet S.

[0036] Next, a summary of the image forming operation of printer 1 will be described. When an image forming task is input into printer 1, the sheet S is fed from the paper tray 15 or the manual paper feed tray 25 and conveyed along the first transport path 21 in the Y1 direction. The sheet S is attracted to the conveyor belt 45 of the transport unit 40 for transport. Then, an image is formed on the sheet S by spraying ink droplets from the recording head unit 34 onto the sheet S. The sheet S with the image formed is then dried by the drying unit 48, conveyed along the second transport path 22 and the third transport path 23, and discharged to the paper output tray 17.

[0037] [Ink Supply Path]

[0038] Next, the ink supply path will be explained. Figure 3 The diagram shows a structure corresponding to one color of ink, but in this embodiment, four colors of ink are used, therefore four systems with identical structures are provided. The printer 1 includes: an ink cartridge mounting section 52 for mounting ink cartridges 51; a suction pump 53 for drawing ink from ink cartridges 51; a filter 54 for filtering the ink drawn by the suction pump 53; a secondary reservoir 55 for storing ink delivered from the suction pump 53; and a delivery pump (not shown) for delivering the ink stored in the secondary reservoir 55 to the recording head unit 34. The ink cartridges 51, filter 54, suction pump 53, and secondary reservoir 55 are connected via a main pipe 56. One end of a relay pipe 57 is connected to a connector 58 located on the back of the printer 1's main housing 10. When using the ink supply device 2, the upstream end of the main pipe 56 is mounted on the other end of the relay pipe 57 instead of being mounted on the ink cartridge 51.

[0039] [Ink supply device]

[0040] Next, the ink supply device 2 will be described. Figure 4 This is a three-dimensional view showing the interior of the ink supply device 2. Figure 5This is a schematic cross-sectional view of the heater unit 71. Figure 6A This is a 3D view of heater 75. Figure 6B This is a 3D view of piping 72.

[0041] The ink supply device 2 includes: an ink cartridge 61 that contains ink; and an ink heating device 7 that heats the ink supplied from the ink cartridge 61. The ink heating device 7 includes: a heater circuit 91 having a heater 75 for heating the ink and an automatic reset bimetallic switch 92 disposed between the heater 75 and the AC power supply A; a relay 5 disposed between the bimetallic switch 92 and the AC power supply A; and a control unit 4 that opens and closes the relay 5 according to the state of the heater circuit 91.

[0042] [ink cartridge]

[0043] Ink supply device 2 (reference) Figure 4 The printer 1 has an ink cartridge mounting section 62 for mounting ink cartridges 61. The ink cartridges 61 have a larger volume than the ink cartridges 51 installed inside the printer 1. In this embodiment, since four colors of ink are used, four ink cartridges 61 are provided, each filled with yellow, black, cyan, and magenta ink respectively. Alternatively, a spare ink cartridge receiving section 63 may be provided for storing spare ink cartridges 61.

[0044] [Heater Unit]

[0045] Each ink cartridge 61 is provided with a heater unit 71.

[0046] [Piping]

[0047] Piping 72 (refer to Figure 3 , Figure 6B The conduit 72 is a pipe made of stainless steel or the like, arranged in a regularly meandering shape. The conduit 72 is held in the front-to-back direction by two support plates 73 made of aluminum or the like. One end of the conduit 72 is connected to the ink cartridge 61 via a relay conduit 74. The other end of the conduit 72 is connected to the connector (coupling) 58 of the printer 1 via the relay conduit 74.

[0048] [Heater]

[0049] Heater 75 (reference) Figure 6A For example, a cord heater made by covering heating wires with silicone resin is provided before and after the piping 72 via a support plate 73, arranged along the piping 72. A power supply line 76 is connected to the heater 75. Figure 6A In the example, five heaters 75 are arranged in parallel before and after the piping 72, for a total of ten heaters 75. However, the number of heaters 75 can be as many as one.

[0050] [case]

[0051] Casing 80 (reference) Figure 5 The housing 75 houses the heater and the piping 72. The housing 80 is formed as a hollow plate in which the dimension in the front-back direction is smaller than the dimensions in the left-right and up-down directions.

[0052] [frame]

[0053] Frame 64 (Reference) Figure 4 The housing 65 comprises: a ridge portion 64E forming the ridge of a cuboid; a base plate portion 64B forming the base of a cuboid; and a partition wall portion 64P dividing the internal space front to back. A housing 65 is formed by mounting side plates and a top plate on the outside of the frame 64. Four heater units 71 are housed on the front side of the partition wall portion 64P, and four ink cartridges 61 are housed on the rear side of the partition wall portion 64P. The four heater units 71 are stacked in a transverse arrangement in the front-to-back direction and are fixed to the frame 64.

[0054] [Electrical Structure]

[0055] Next, the electrical structure of the ink heating device 7 in the ink supply device 2 will be described. Figure 7 This is the circuit diagram of ink heating device 7. Figure 8 This is the circuit diagram of heater circuit 91. Figure 9 This is a timing diagram of the detection signal.

[0056] Ink heating device 7 (reference) Figure 7 It includes: a heater circuit 91; a relay 5 disposed between the heater circuit 91 and the AC power supply A; a control unit 4 that controls the relay 5; and an operation unit 6 that receives operations. At least one heater circuit 91 is provided for each color of ink. Figure 7 In the example, for convenience, a heater circuit 91 is shown according to each color of ink (Y, Bk, C, M), but in... Figure 6A In the case where multiple heaters 75 are arranged side by side according to each color of ink as shown, the number of heater circuits 91 is also multiple according to each color of ink.

[0057] Heater circuit 91 (reference) Figure 8 The device includes: a heater 75 for heating ink; a bimetallic switch 92, which is automatically reset, disposed between the heater 75 and the relay 5; a detection unit 93 that outputs a detection signal indicating that the bimetallic switch 92 is energized; and a drive element 94 that drives the heater 75. The relay 5 is disposed between the bimetallic switch 92 and the AC power supply A. The control unit 4 controls the relay 5 based on the state of the detection signal output from the detection unit 93.

[0058] The automatic reset bimetallic switch 92 is disconnected when the temperature of the heater 75 is above a threshold (e.g., 75°C) and connected when the temperature of the heater 75 is below the threshold.

[0059] The detection unit 93 outputs a detection signal when the bimetallic switch 92 is energized, and stops outputting the detection signal when the bimetallic switch 92 is not energized. The detection signal is, for example, a zero-crossing signal indicating the moment when the AC voltage is 0V (see reference). Figure 9 (a) in the middle.

[0060] The driving element 94 is, for example, a triac, which changes the duty cycle of the voltage according to a remote signal supplied from the control unit 4.

[0061] The control unit 4 is an integrated circuit that incorporates logic circuitry. The control unit 4 controls the temperature of the heater 75 by changing the duty cycle of the voltage output by the drive element 94 via a remote signal. Alternatively, the control unit 4 can also be a processor-based component that collaborates with software.

[0062] Furthermore, the control unit 4 controls the relay 5 based on the state of the detection signal output from the detection unit 93. Specifically, the control unit 4 disconnects the relay 5 if the state where the detection signal has stopped has lasted for a predetermined time or longer. On the other hand, the control unit 4 does not disconnect the relay 5 if the state where the detection signal has stopped has lasted for less than a predetermined time.

[0063] Furthermore, if the detection signal in any heater circuit 91 has been stopped for a predetermined time or longer, the control unit 4 will disconnect the relay 5. On the other hand, the control unit 4 will not disconnect the relay 5 if all detection signals from the heater circuit 91 have stopped.

[0064] The detection signal stops when the temperature of the heater 75 reaches a predetermined value and the bimetallic switch 92 opens. For example, the bimetallic switch 92 opens if the heater 75 overheats due to a malfunction in the control unit 4, drive element 94, etc. Most malfunctions in the control unit 4 and drive element 94 are permanent, so it is possible for the heater to overheat for an extended period of time.

[0065] The detection signal may sometimes stop for reasons other than permanent faults. For example, when the drive element 94 is a bidirectional thyristor, overshoot may occur during a pulsed voltage rise, sometimes resulting in momentary overheating. Alternatively, momentary overheating may also occur due to voltage drops from nearby high-power applications, inrush currents during momentary resets, or surge currents from lightning strikes. Even in these cases, the bimetallic switch 92 will open, thus stopping the detection signal.

[0066] Furthermore, in the event of a power outage or accidental disconnection of the power cord from AC power source A, the heating of heater 75 will stop. Therefore, bimetallic switch 92 will not open, but bimetallic switch 92 will stop being powered, and thus the detection signal will also stop.

[0067] The operating unit 6, for example a tactile switch, is located on the upper part of the housing 65. After the relay 5 is disconnected, the control unit 4 turns on the relay 5 upon receiving an operation of pressing the tactile switch (an example of a prescribed operation).

[0068] [Operation of the ink heating device]

[0069] Next, the operation of the ink heating device 7 will be explained. Figure 10 This is a flowchart illustrating the operation of the ink heating device 7. Initially, the control unit 4 determines whether all detection signals from the heater circuit 91 have stopped (step S01). If it is determined that all detection signals from the heater circuit 91 have stopped (step S01: Yes), the control unit 4 repeats the process of step S01. On the other hand, if it is determined that not all detection signals from the heater circuit 91 have stopped (step S01: No), the control unit 4 determines whether the detection signal from any one heater circuit 91 has stopped (step S03). If it is determined that the detection signal from any one heater circuit 91 has stopped (step S03: Yes), the control unit 4 starts timing (step S05). On the other hand, if it is determined that the detection signal from any one heater circuit 91 has not stopped (step S03: No), the control unit 4 repeats the process of step S01.

[0070] If timing begins in step S05, the control unit 4 determines whether the time T being timed is greater than or equal to the predetermined time T0 (step S07). Figure 9 (c) and Figure 9 As shown in (d), when the timing time T is greater than or equal to the predetermined time T0 (step S07: Yes), the control unit 4 sends a control signal to the relay 5 to disconnect the relay 5 (step S11). On the other hand, as... Figure 9As shown in (b), if the time T is less than the predetermined time T0 (step S07: No), the control unit 4 determines whether to restart the output of the stopped detection signal (step S09). If the output of the stopped detection signal is restarted (step S09: Yes), the control unit 4 repeats the process of step S01. On the other hand, if the output of the stopped detection signal is not restarted (step S09: No), the control unit 4 repeats the process of step S07.

[0071] If relay 5 is disconnected in step S11, the control unit 4 determines whether the operation unit 6 has received the specified operation (step S13). If it is determined that the operation unit 6 has received the specified operation (step S13: Yes), the control unit 4 turns on relay 5 by sending a control signal to relay 5 (step S15). On the other hand, if it is determined that the operation unit 6 has not received the specified operation (step S13: No), the control unit 4 repeats the process of step S13.

[0072] According to the ink heating device 7 described above, in the event of overheating, the bimetallic switch 92 is opened, thereby stopping the power supply to the heater 75, thus shortening the time from the occurrence of overheating to the cessation of heating.

[0073] Furthermore, according to the ink heating device 7 of this embodiment, if the detection signal has been stopped for a specified time or more, the relay 5 is disconnected. Therefore, in cases where the possibility of permanent failure is high, heating will not restart even if the bimetallic switch 92 is reset.

[0074] Furthermore, according to the ink heating device 7 of this embodiment, after the relay 5 is disconnected, the relay 5 is reconnected when the operation unit 6 receives a specified operation, so that heating can be restarted after a person confirms that it is safe.

[0075] Furthermore, according to the ink heating device 7 of this embodiment, the relay 5 is not disconnected if the detection signal has been stopped for less than a predetermined time. Therefore, in cases where the possibility of a permanent failure is low, heating can be restarted by resetting the bimetallic switch 92. Additionally, while setting the threshold of the bimetallic switch 92 high to avoid reacting to the aforementioned instantaneous overheating could increase the frequency of exposure to high temperatures and reduce safety, in this embodiment, even if the bimetallic switch 92 disconnects due to instantaneous overheating, the relay 5 will not disconnect. Therefore, it is not necessary to set the threshold of the bimetallic switch 92 high. Thus, a decrease in safety can be avoided.

[0076] Furthermore, according to the ink heating device 7 of this embodiment, if the detection signal in any heater circuit 91 has been stopped for a specified time or more, the relay 5 is disconnected. Therefore, even if the bimetallic switch 92 is reset, heating will not restart if there is a high possibility of permanent failure.

[0077] Furthermore, according to the ink heating device 7 of this embodiment, the relay 5 is not disconnected when all detection signals from the heater circuit 91 have stopped. Therefore, the process of disconnecting the relay 5 when the power supply from the AC power supply A is stopped can be eliminated.

[0078] The above-described embodiments can also be modified as follows.

[0079] The above embodiment shows an example where the driving element 94 is a bidirectional thyristor, but the driving element 94 can also be a solid-state relay, etc.

[0080] The above embodiment shows an example where the detection signal is a zero-crossing signal, but the detection signal can also be a voltage detection signal indicating that a voltage has been detected, a current detection signal indicating that a current has been detected, etc.

[0081] The above embodiment illustrates an example where relay 5 disconnects when the state of detection signal cessation lasts for a predetermined time or longer. However, it can also be configured to disconnect relay 5 even when the phenomenon of detection signal cessation lasting for less than a predetermined time occurs repeatedly. According to this configuration, the safety of the ink supply device 2 can be further improved.

[0082] The above embodiment shows an example where the operation unit 6 is disposed in the housing 65 of the ink supply device 2, but it can also be configured so that the prescribed operations are performed using the operation panel of the printer 1. With this configuration, it is easy to restart the heating of the ink.

Claims

1. An ink heating device, characterized in that, It has a heater circuit, a relay, and a control unit, wherein, The heater circuit includes: a heater for heating the ink; an automatic reset bimetallic switch disposed between the heater and a power source; and a detection unit that outputs a detection signal indicating that the bimetallic switch is energized. The relay is positioned between the bimetallic switch and the power supply. The control unit switches the relay on and off based on the state of the heater circuit. If the detection signal has been stopped for a specified period of time, the control unit disconnects the relay.

2. The ink heating device according to claim 1, characterized in that, It has an operating unit that accepts operations. After the control unit disconnects the relay, it reconnects the relay upon receiving a specified operation from the operation unit.

3. The ink heating device according to claim 1, characterized in that, If the control unit does not disconnect the relay if the state in which the detection signal has stopped continues for less than a predetermined time.

4. The ink heating device according to claim 1, characterized in that, Having multiple of the aforementioned heater circuits, If the detection signal in any of the heater circuits has been stopped for a specified period of time, the control unit disconnects the relay.

5. The ink heating device according to claim 4, characterized in that, The control unit does not disconnect the relay when all detection signals from the heater circuit have stopped.

6. The ink heating device according to claim 1, characterized in that, The bimetallic switch is switched to the energized state when the temperature of the heater is below a threshold, and switched to the de-energized state when the temperature of the heater is above the threshold.

7. An ink supply device, characterized in that, It has an ink cartridge and the ink heating device according to claim 1, wherein, The ink cartridge contains the ink. The ink heating device heats the ink dispensed from the ink cartridge.

8. An image forming system, characterized in that, It has an inkjet recording device and an ink supply device as described in claim 7. The inkjet recording apparatus includes: a transport unit that transports a sheet-like recording medium; and an inkjet head that ejects ink supplied from the ink supply device onto the recording medium transported by the transport unit.

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