Cooling device, image forming device

Abstract

To discharge the refrigerant liquid from the tank of the cooling system without using a pump when the liquid level in the tank exceeds the permissible range. [Solution] The cooling system comprises a main tank 70, a supply device 73 for supplying refrigerant liquid to the main tank 70, a drain tank 76, a drain pipe 75, and a liquid detection device 77. The drain tank 76 is positioned lower than the main tank 70. The drain pipe 75 is connected to an outlet 70c formed in the main tank 70, forming a flow path from the outlet 70c through a specific position P1 to the drain tank 76. The liquid detection device 77 detects the refrigerant liquid in the drain pipe 75 at the specific position P1. The specific position P1 is higher than the outlet 70c and lower than the upper end 70a of the storage area for the refrigerant liquid in the main tank 70.

Description

Technical Field

[0001] The present invention relates to a cooling device and an image forming apparatus that cool an object to be cooled with a refrigerant liquid.

Background Art

[0002] Devices constituting an image forming apparatus tend to become hot due to the acceleration of printing processing.

[0003] Therefore, the image forming apparatus may include a cooling device. For example, it is known that an electrophotographic image forming apparatus includes a liquid cooling type cooling device that cools a developing device (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, a liquid cooling type cooling device includes a tank for storing a refrigerant liquid, and cools the object to be cooled by circulating the refrigerant liquid through a circulation path including the tank and the object to be cooled.

[0006] Furthermore, the cooling device includes a liquid level gauge for detecting the liquid level in the tank, and a replenishing device for replenishing the refrigerant liquid to the tank. The replenishing device operates so that the detected liquid level of the liquid level gauge is maintained at a reference level.

[0007] In the cooling device, when a device abnormality such as a failure of the replenishing device occurs, the liquid level in the tank may exceed an allowable range. It is desirable that the replacement of the unit including the abnormal device be performed in a situation where the tank is empty.

[0008] On the other hand, providing a pump for discharging the refrigerant liquid from the tank is undesirable because it would increase costs.

[0009] The object of the present invention is to provide a cooling device and an image forming apparatus that can discharge refrigerant liquid from a tank without using a pump when the liquid level in the tank exceeds an acceptable range. [Means for solving the problem]

[0010] A cooling device according to one aspect of the present invention comprises a main tank for storing refrigerant liquid and a supply device for supplying the refrigerant liquid to the main tank, and cools the object to be cooled by circulating the refrigerant liquid in a circulation path including the main tank and the object to be cooled. The cooling device comprises a drain tank, a drain pipe, and a liquid detection device. The drain tank is located at a lower position than the main tank and is capable of storing the refrigerant liquid. The drain pipe is connected to an outlet formed in the main tank and is a pipe that forms a flow path from the outlet through a specific position to the drain tank. The liquid detection device detects the refrigerant liquid in the drain pipe at the specific position. The specific position is higher than the outlet and lower than the upper end of the storage area for the refrigerant liquid in the main tank.

[0011] An image forming apparatus according to another aspect of the present invention comprises a printing apparatus for forming an image on a sheet, and a cooling apparatus for cooling a part of the printing apparatus. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a cooling device and an image forming apparatus that can discharge refrigerant liquid from a tank without using a pump when the liquid level in the tank exceeds an acceptable range. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a configuration diagram of an image forming apparatus according to an embodiment. [Figure 2] Figure 2 shows an image forming apparatus when the nozzle cover device is in the nozzle closed state. [Figure 3] Figure 3 is a block diagram showing the configuration of the control device in the image forming apparatus according to the embodiment. [Figure 4] Figure 4 is a diagram showing the configuration of the main cooling unit of the cooling device in the image forming apparatus according to the embodiment. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described below with reference to the drawings. Note that the following embodiments are merely examples of the present invention and do not limit the technical scope of the present invention.

[0015] The image forming apparatus 10 according to this embodiment includes a printing device 4 that performs a printing process to form an image on a sheet 9. In this embodiment, the printing device 4 performs the printing process using an inkjet method.

[0016] For example, the image forming apparatus 10 is a printer, facsimile machine, copier, or multifunction device. The sheet 9 is a sheet-like image forming medium such as paper or resin film.

[0017] [Configuration of the image forming apparatus 10] The image forming apparatus 10 includes a sheet storage unit 12, a sheet transport device 3, a printing device 4, and an ink supply device 40.

[0018] The sheet transport device 3, the printing device 4, the ink supply device 40, and the control device 8 are housed within the main body 1 of the image forming apparatus 10.

[0019] The sheet conveying device 3 conveys the sheets 9 stored in the sheet storage section 12 one by one along the sheet conveying path 30. The printing device 4 includes a feeding device 31, a first belt conveying device 32, a second belt conveying device 33, and a discharge conveying device 34.

[0020] The sheet feeding device 31 feeds the sheets 9 one by one from the sheet storage section 12 to the sheet conveyance path 30, and further conveys the sheet 9 to the first belt conveyance device 32.

[0021] The first belt conveyance device 32 takes over the conveyance of the sheet 9 from the sheet feeding device 31, and further conveys the sheet 9 to the second belt conveyance device 33.

[0022] The second belt conveyance device 33 takes over the conveyance of the sheet 9 from the first belt conveyance device 32, and further conveys the sheet 9 to the discharge conveyance device 34.

[0023] The discharge conveyance device 34 takes over the conveyance of the sheet 9 from the second belt conveyance device 33, and sends out the sheet 9 with an image formed thereon to the outside of the main body 1. For example, the discharge conveyance device 34 sends out the sheet 9 to a discharge tray or another device in the subsequent stage.

[0024] The printing device 4 includes a plurality of inkjet heads 4x corresponding to a plurality of developing colors. Each inkjet head 4x has an ink ejection section 4a including a plurality of nozzles that eject ink. Each inkjet head 4x forms an image on the sheet 9 by ejecting ink onto the sheet 9.

[0025] The ink supply device 40 supplies inks of different colors to the plurality of inkjet heads 4x. In the present embodiment, the printing device 4 includes four inkjet heads 4x corresponding to four colors of ink, namely black, cyan, magenta, and yellow.

[0026] The image forming apparatus 10 further includes a nozzle cover device 5 and a waste ink recovery device 6. The nozzle cover device 5 has a plurality of caps 51 that cover the ink ejection sections 4a of the plurality of inkjet heads 4x.

[0027] The nozzle cover device 5 can switch between a nozzle-closed state, in which the ink ejection portions 4a of the multiple inkjet heads 4x are covered with multiple caps 51, and a nozzle-open state, in which the ink ejection portions 4a of the multiple inkjet heads 4x are open.

[0028] Figure 1 shows the image forming apparatus 10 when the nozzle cover device 5 is in the nozzle open state, and Figure 2 shows the image forming apparatus 10 when the nozzle cover device 5 is in the nozzle closed state.

[0029] For example, the nozzle cover device 5 comprises a cap unit 50, a head moving device 52, and a cap moving device 53. The cap unit 50 includes a plurality of caps 51.

[0030] The head moving device 52 moves the multiple inkjet heads 4x between a print position and a maintenance position. The print position is a position along the conveyor belt of the first belt conveyor device 32 (see Figure 1). The multiple inkjet heads 4x can perform the print process when they are in the print position.

[0031] The maintenance position is located further from the first belt conveyor 32 than the print position (see Figure 2). When multiple inkjet heads 4x are located at the maintenance position, a space is formed between the ink ejection sections 4a of the multiple inkjet heads 4x and the first belt conveyor 32 into which the cap unit 50 can be inserted.

[0032] The cap moving device 53 moves the cap unit 50 between a cap position and a retracted position. The cap position is the position of the cap unit 50 when the multiple caps 51 cover the ink ejection sections 4a of the multiple inkjet heads 4x. The retracted position is a position further away from the multiple inkjet heads 4x than the cap position.

[0033] When multiple inkjet heads 4x are in the maintenance position, the cap moving device 53 can move the cap unit 50 between the retracted position and the cap position. When the cap unit 50 is in the retracted position, the head moving device 52 can move the multiple inkjet heads 4x between the print position and the maintenance position.

[0034] The waste ink recovery device 6 is a device that recovers waste ink generated in the printing device 4 into the waste ink tank 60. In this embodiment, the waste ink is the ink ejected from the ink ejection sections 4a of the multiple inkjet heads 4x into the multiple caps 51 when the nozzle cover device 5 is in the nozzle closed state.

[0035] The waste ink recovery device 6 comprises a waste ink tank 60, a recovery tube 61 connecting the cap unit 50 and the waste ink tank 60, and a suction pump 62. The insides of the multiple caps 51 and the waste ink tank 60 are in communication through the recovery tube 61.

[0036] The suction pump 62 reduces the pressure inside the waste ink tank 60 to a negative pressure, thereby transporting the waste ink from the multiple caps 51 into the waste ink tank 60 via the recovery tube 61.

[0037] Furthermore, the image forming apparatus 10 also includes an operating device 801, a display device 802, and a control device 8 (see Figure 1).

[0038] The operating device 801 is a device that accepts human input. For example, the operating device 801 includes operation buttons and a touch panel. The display device 802 is capable of displaying information. For example, the display device 802 includes a display panel such as a liquid crystal panel.

[0039] The control device 8 performs various data processing and controls the equipment provided by the image forming apparatus 10.

[0040] As shown in Figure 3, the control device 8 includes a CPU (Central Processing Unit) 81, RAM (Random Access Memory) 82, a secondary storage device 83, a signal interface 84, and a communication device 85, among others.

[0041] CPU81 is an example of a processor that performs various data processing and control tasks by executing computer programs.

[0042] RAM82 is a volatile memory device that can be read by a computer. RAM82 temporarily stores the computer program executed by CPU81 and the data that CPU81 outputs and references during the process of performing various operations.

[0043] The secondary storage device 83 is a non-volatile storage device that can be read by a computer. The secondary storage device 83 is capable of storing and updating the computer program and various types of data. For example, some or all of flash memory, SSD (Solid State Drive), and hard disk drive may be used as the secondary storage device 83.

[0044] The signal interface 84 converts signals output by various sensors into digital data and transmits the converted digital data to the CPU 81. Furthermore, the signal interface 84 converts control commands output by the CPU 81 into control signals and transmits the control signals to the controlled device.

[0045] The communication device 85 is capable of communicating with a host device (not shown) and other devices. The host device is an information processing device such as a personal computer or smartphone operated by a user.

[0046] For example, the CPU 81 receives a print job from the host device via the communication device 85. The printing device 4 forms the image specified by the print job on the sheet 9.

[0047] The CPU 81 includes a plurality of processing modules that are realized by executing the computer program. The plurality of processing modules include a main control unit 8a and a print control unit 8b, etc.

[0048] The main control unit 8a performs control to initiate various processes in response to operations on the operating device 801, as well as control of the display device 802.

[0049] The print control unit 8b causes the sheet transport device 3 to perform the sheet transport process. Furthermore, the print control unit 8b causes the print device 4 to perform the print process in synchronization with the transport of the sheet 9 by the sheet transport device 3.

[0050] The image forming apparatus 10 further includes a liquid-cooled cooling device 7 that cools a portion of the printing device 4 (see Figures 1 and 3). The plurality of processing modules of the CPU 81 include a cooling control unit 8c that controls the cooling device 7.

[0051] Incidentally, the liquid-cooled cooling system 7 includes a main tank 70 for storing refrigerant liquid, and cools the object to be cooled by circulating the refrigerant liquid through a circulation path that includes the main tank 70 and the object to be cooled. For example, the refrigerant liquid is water.

[0052] In this embodiment, the objects to be cooled are the multiple inkjet heads 4x in the printing device 4.

[0053] Furthermore, the cooling system 7 includes a liquid level gauge 74 for detecting the liquid level in the main tank 70, and a replenishment device 73 for supplying the refrigerant liquid to the main tank 70 (see Figure 4). The replenishment device 73 operates to maintain the liquid level detected by the liquid level gauge 74 at a reference level.

[0054] In this embodiment, the cooling control unit 8c operates the replenishment device 73 when the liquid level detected by the liquid level gauge 74 falls below the reference level. On the other hand, the cooling control unit 8c stops the operation of the replenishment device 73 when the liquid level detected by the liquid level gauge 74 does not fall below the reference level.

[0055] In the cooling system 7, if an equipment malfunction occurs, such as a failure of the replenishment device 73, the liquid level in the main tank 70 may exceed the permissible range. It is desirable to replace the unit containing the malfunctioning equipment when the tank is empty.

[0056] On the other hand, providing a pump for discharging the refrigerant liquid from the main tank 70 is undesirable because it would increase costs.

[0057] The cooling device 7 is configured to discharge the refrigerant liquid from the main tank 70 without using a pump when the liquid level in the main tank 70 exceeds an acceptable range.

[0058] The cooling system 7 comprises a heat exchange section 7a, a main cooling unit 7b, and a plurality of circulation tubes 7c. The main cooling unit 7b includes a main tank 70, a circulation pump 71, a radiator 72, a replenishment device 73, and a liquid level gauge 74.

[0059] The heat exchange unit 7a performs heat exchange between the refrigerant liquid and the plurality of inkjet heads 4x. As a result, the heat exchange unit 7a cools each of the inkjet heads 4x that are at a higher temperature than the refrigerant liquid.

[0060] Multiple circulation tubes 7c connect the main tank 70, the heat exchange unit 7a, the radiator 72, and the circulation pump 71, forming a circulation path for the refrigerant liquid. The circulation pump 71 circulates the refrigerant liquid in the main tank 70 through the circulation path.

[0061] The circulation pump 71 circulates the refrigerant liquid through the circulation path. That is, the circulation pump 71 circulates the refrigerant liquid between the main tank 70, the heat exchange unit 7a, and the radiator 72. The radiator 72 radiates the heat of the coolant liquid.

[0062] In this embodiment, the liquid level gauge 74 is a float-type water level gauge. The liquid level gauge 74 is an example of a liquid level detection device that detects the liquid level in the main tank 70.

[0063] The replenishment device 73 comprises an auxiliary tank 73a and a replenishment pump 73b. The auxiliary tank 73a contains the refrigerant liquid. The replenishment pump 73b pumps the refrigerant liquid in the auxiliary tank 73a to the main tank 70. In this embodiment, the replenishment pump 73b is a diaphragm pump.

[0064] The liquid level gauge 74 detects whether the level of the refrigerant liquid in the main tank 70 is at or below a reference level. When the liquid level gauge 74 detects that the level of the refrigerant liquid in the main tank 70 is below the reference level, the replenishment pump 73b operates.

[0065] The cooling device 7 further comprises a drain pipe 75, a drain tank 76 capable of storing the refrigerant liquid, and a liquid detection sensor 77 (see Figure 4).

[0066] The wastewater tank 76 is positioned lower than the main tank 70. In this embodiment, the waste ink tank 60 also serves as the wastewater tank 76. To revert to the original design, the wastewater tank 76 also serves as the waste ink tank 60.

[0067] The drain pipe 75 is connected to an outlet 70c formed in the main tank 70, and forms a flow path for the refrigerant liquid from the outlet 70c through a specific position P1 to the drain tank 76. The cross-sectional area of ​​the drain pipe 75 is smaller than the cross-sectional area of ​​the main tank 70.

[0068] The specific location P1 is the highest point in the path of the drain pipe 75. In other words, the portion of the drain pipe 75 other than the specific location P1 is located at a lower position than the specific location P1.

[0069] The liquid detection sensor 77 detects the refrigerant liquid in the drain pipe 75 at a specific position P1. For example, the liquid detection sensor 77 is a capacitive level switch or an electrode level switch. The liquid detection sensor 77 is an example of a liquid detection device.

[0070] The specific position P1 is higher than the outlet 70c and lower than the upper end 70a of the storage area for the refrigerant liquid in the main tank 70. The upper end 70a of the storage area is higher than the reference level.

[0071] The liquid level in the drain pipe 75 is the same as the liquid level in the main tank 70. The liquid detection sensor 77 detects that the level of the refrigerant liquid in the main tank 70 has reached its upper limit.

[0072] The liquid level gauge 74 detects a liquid level lower than a specific position P1 in the main tank 70. That is, the reference level is lower than the specific position P1. Therefore, if the cooling device 7 is operating normally, the level of the refrigerant liquid will not rise to the specific position P1.

[0073] If the replenishment pump 73b malfunctions or the liquid level gauge 74 malfunctions and the replenishment pump 73b runs out of control, the level of the refrigerant liquid in the main tank 70 reaches its upper limit, and the liquid detection sensor 77 detects the refrigerant liquid at a specific position P1. Furthermore, if the refrigerant liquid flows beyond the specific position P1 towards the drain tank 76, the refrigerant liquid in the main tank 70 is discharged into the drain tank 76 by the siphon effect.

[0074] In this embodiment, the discharge port 70c is formed on the bottom surface 70b of the main tank 70 (see Figure 4). The drain tank 76 is positioned lower than the bottom surface 70b of the main tank 70. As a result, all of the refrigerant liquid in the main tank 70 is discharged into the drain tank 76.

[0075] The cooling control unit 8c performs error processing when the refrigerant liquid at a specific position P1 is detected by the liquid detection sensor 77. The error processing includes stopping the supply pump 73b and the circulation pump 71, and outputting an alarm through either or both of the display device 802 and the communication device 85. The display device 802 and the communication device 85 are examples of output devices, respectively.

[0076] In this embodiment, the cooling device 7 comprises a tank unit 70x and a unit mounting section 700 (see Figure 4). The tank unit 70x includes a main tank 70 and a liquid level gauge 74. The unit mounting section 700 is located inside the main body 1. The tank unit 70x is detachably mounted on the unit mounting section 700.

[0077] If the liquid level gauge 74 is a float-type water level gauge, there is a high probability that the liquid level gauge 74 will malfunction when the level of the refrigerant liquid in the main tank 70 reaches its upper limit. In this embodiment, when the liquid level gauge 74 malfunctions, the tank unit 70x to which the liquid level gauge 74 is attached can be easily replaced while the main tank 70 is empty.

[0078] [Notes on the invention] The following is an overview of the invention extracted from the above-described embodiments. Note that each configuration and processing function described below can be selected and combined as desired.

[0079] <Note 1> A cooling device comprising a main tank for storing refrigerant liquid and a supply device for supplying the refrigerant liquid to the main tank, wherein the cooling device cools the object to be cooled by circulating the refrigerant liquid through a circulation path including the main tank and the object to be cooled, A drain tank is located at a lower position than the main tank and is capable of storing the refrigerant liquid, A drain pipe connected to an outlet formed in the main tank, forming a flow path from the outlet through a specific location to the drain tank, The system includes a liquid detection device that detects the refrigerant liquid in the drain pipe at the specified location, A cooling device in which the specified position is higher than the outlet and lower than the upper end of the storage area for the refrigerant liquid in the main tank.

[0080] <Note 2> The aforementioned outlet is formed on the bottom surface of the main tank, The drainage tank is located at a lower position than the bottom surface of the main tank, and is part of the cooling device described in Appendix 1.

[0081] <Note 3> The cooling device according to Appendix 1 or Appendix 2, comprising a unit mounting section to which a tank unit including the main tank is detachably mounted.

[0082] <Note 4> The main tank is equipped with a liquid level detection device that detects a liquid level lower than the specified position, The tank unit is the cooling device according to Appendix 3, including the main tank and the liquid level detection device.

[0083] <Note 5> The object to be cooled includes an inkjet head that forms an image on the sheet by ejecting ink onto the sheet, The cooling device according to any one of the appendices 1 to 4, wherein the drainage tank also serves as a waste ink tank for containing the waste ink in a waste ink recovery device that recovers the waste ink generated by the inkjet head.

[0084] <Note 6> A printing device that forms an image on a sheet, An image forming apparatus comprising a cooling device described in any one of the appendices 1 to 5 for cooling a part of the printing device. [Explanation of Symbols]

[0085] 4: Printing device 4a: Ink ejection unit 4x: Inkjet head 5: Nozzle cover device 6: Waste ink collection device 7: Cooling device 7a: Heat exchange section 7b: Main cooling unit 7c: Circulatory tube 8: Control device 10: Image forming apparatus 30: Sheet transport path 60: Waste ink tank 61: Recovery tube 62: Suction pump 70: Main tank 70c: Discharge port 70x: Tank Unit 71: Circulation pump 72: Radiator 73: Supply device 73a: Auxiliary tank 73b: Refill pump 74:Liquid level gauge 75: Drainage pipe 76: Drainage tank 77: Liquid detection sensor 700: Unit mounting section

Claims

1. A cooling device comprising a main tank for storing refrigerant liquid and a supply device for supplying the refrigerant liquid to the main tank, wherein the cooling device cools the object to be cooled by circulating the refrigerant liquid through a circulation path including the main tank and the object to be cooled, A drain tank is located at a lower position than the main tank and is capable of storing the refrigerant liquid, A drain pipe connected to an outlet formed in the main tank, forming a flow path from the outlet through a specific location to the drain tank, The system includes a liquid detection device that detects the refrigerant liquid in the drain pipe at the specified location, A cooling device in which the specified position is higher than the outlet and lower than the upper end of the storage area for the refrigerant liquid in the main tank.

2. The aforementioned outlet is formed on the bottom surface of the main tank, The cooling device according to claim 1, wherein the drainage tank is positioned lower than the bottom surface of the main tank.

3. The cooling device according to claim 1 or claim 2, further comprising a unit mounting section to which a tank unit including the main tank is detachably mounted.

4. The main tank is equipped with a liquid level detection device that detects a liquid level lower than the specified position, The cooling apparatus according to claim 3, wherein the tank unit includes the main tank and the liquid level detection device.

5. The object to be cooled includes an inkjet head that forms an image on the sheet by ejecting ink onto the sheet, The cooling device according to claim 1 or claim 2, wherein the drainage tank also serves as a waste ink tank for containing the waste ink in a waste ink recovery device that recovers the waste ink generated by the inkjet head.

6. A printing device that forms an image on a sheet, An image forming apparatus comprising a cooling device according to claim 1 or 2 for cooling a part of the printing device.

Images