Fixing device and heating device

Abstract

To solve problems of paper wrinkles and ink friction caused by stress applied to a recording material in a fixation nip part when one of upper and lower belts is slipped and a speed difference between the upper and lower belts is generated.SOLUTION: A driving roller for driving a belt is cleaned by a cleaning member. A conveyance roller for driving the belt is cleaned using a web, which prevents slip after endurance.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a fixing device that fixes an image on a recording material and an image forming apparatus equipped with the fixing device. [Background technology]

[0002] If the ink immediately after printing with an inkjet printing device is touched before it has dried sufficiently, the image may become distorted or the ink may get on your hands. Inkjet printing devices with high printing speeds may overlap a second sheet of printing material before the ink on the first sheet has dried, causing the back side of the first sheet to become dirty. For this reason, inkjet printing devices, particularly high-speed printing models, require a means to dry the ink and fix it on the printing material.

[0003] In high-speed inkjet recording devices, a thermal fixing method is used as a means for drying and fixing the ink, in which the recording material immediately after recording is heated to a high temperature suddenly. The image forming device disclosed in Patent Document 1 uses a method in which the recording material on which ink has been printed is sandwiched between a pair of belts and the ink is fixed to the recording material by applying heat and pressure (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-15290 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a fixing device that fixes ink to a recording material by sandwiching the recording material between a pair of heated belts, one method of heating the belt is to heat the belt without contact using radiant light from a halogen heater or the like (Figure 1).

[0006] In order to provide a high-speed, long-life fixing device, it is necessary to drive the upper and lower belts stably for a long period of time. If a speed difference occurs between the upper and lower belts due to slippage of one of the belts, stress is applied to the recording material in the fixing nip, causing problems such as paper wrinkles and ink rubbing.

[0007] The present invention has been developed in view of the above problems, and an object of the present invention is to propose a fixing device that can stably drive a belt even after long-term use in a configuration in which the belt is heated by a heater. [Means for solving the problem]

[0008] In order to achieve the above object, the fixing device of the present invention dries and fixes ink on a recording material, the fixing device comprising a belt (21, 31), at least two rollers (22, 24, 32, 34) around which the belt (21, 31) is stretched, and the belt (21, 31) serves as a drive roller driven by at least one of the rollers (22-24, 32-34), and is characterized in that a cleaning unit (60, 70) is disposed on the drive roller. Effect of the Invention

[0009] According to the present invention, by cleaning the drive roller that drives the belt, the belt can be driven stably for a long period of time. [Brief description of the drawings]

[0010] [Figure 1] 4 is a cross-sectional view of the fixing device for explaining a belt heating method. [Diagram 2] FIG. 2 is a cross-sectional view of the fixing device illustrating a cleaning unit according to the first embodiment. [Diagram 3] FIG. 11 is a cross-sectional view of a fixing device illustrating a cleaning unit according to a second embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view of a fixing device for explaining a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. Note that, although the following describes an example in which the present invention is applied to an inkjet type full-color image forming apparatus, the present invention is not limited to this, and can also be applied to various types of image forming apparatuses, monochrome image forming apparatuses, etc. EXAMPLES

[0012] The fixing device is a block diagram of an inkjet recording apparatus that dries and fixes ink printed on a recording material by an inkjet method.

[0013] <Fixing device> The fixing device 100 is composed of an upper belt unit 20 and a lower belt unit 30, and a nip N is formed by pressing the upper and lower belts together.

[0014] The upper belt 21 is stretched around three rollers, an upper driving roller 22, an upper tension roller 23, and an upper steering roller 24. Similarly, the lower belt 31 is stretched around three rollers, a lower driving roller 32, a lower tension roller 33, and a lower steering roller .

[0015] The three rollers are common to the upper and lower units, and the tension roller and steering roller are metal rollers with an outer diameter of 50 mm and a thickness of 10 mm. They can be made of iron or aluminum. In this embodiment, aluminum metal rollers are used.

[0016] The upper and lower drive rollers 22, 32 are metal rollers with a rubber layer on the outside, which gives them a higher coefficient of friction with the inner surface of the belt than the other rollers. In this embodiment, a 5 mm thick rubber layer is provided on the outer periphery of an aluminum roller with an outer diameter of 40 mm. The type of rubber that can be used includes urethane rubber and silicone rubber. In this embodiment, urethane rubber is used.

[0017] When a motor (not shown) applies torque to the drive rollers, the upper belt 21 and the lower belt 22 rotate. The recording material S with an unfixed image thereon is transported in the direction of the arrow. By performing a long nip and heating with both the upper belt and the lower belt, the ink applied to the recording material S penetrates into the paper, achieving high print quality.

[0018] <Heating source> The heater 40 is a heat source disposed in the upper unit, and the side opposite the nip is covered by a reflector 41. The heater 40 can quickly apply heat to the image surface of the recording material S by directly heating the nip portion of the upper belt 21. The heater can be a halogen heater or a carbon heater. In this embodiment, a halogen heater is used. Since the heater 40 directly heats the belt, it has good thermal response, and by switching the output when switching the paper type, the fixing operation can be continued without waiting time.

[0019] The lower belt unit 30 is stretched around three rollers. The heater 42 is a halogen heater disposed in the lower steering roller 34. The lower belt 31 is heated by the lower steering roller 34 heated by the heater 42. The lower belt unit 30 can also directly heat the lower belt 31 with a halogen heater like the upper belt unit 20, but since the lower belt unit does not heat the image surface of the recording material S, it does not require a thermal response like the upper belt unit, and therefore a halogen heater in the steering roller is used as the heating source.

[0020] The upper belt and the lower belt form a nip N, which heats the ink and the recording material S. The ink applied to the recording material S permeates into the recording material S, and the image is fixed to the recording material S.

[0021] <Cleaning unit> Next, we will discuss the cleaning unit.

[0022] 2 is a diagram illustrating the cleaning unit 60 and the cleaning unit 70 of the embodiment 1. The cleaning unit 60 is disposed inside the upper belt unit 20, and the cleaning unit 70 is disposed inside the lower belt unit 30.

[0023] The cleaning units 60, 70 are cleaning mechanisms that remove dirt adhering to the surfaces of the drive rollers 22, 32. The drive rollers are provided with a rubber layer, which contains plasticizers, vulcanizing agents, release agents, low molecular weight components, etc., and when used for a long period of time, these components bleed out and adhere to the roller surface, affecting the coefficient of friction with the upper belt 21 or lower belt 31. As a result, the upper belt 21 or lower belt 31 may slip.

[0024] In order to prevent such slippage, the cleaning units 60, 70 are provided. The cleaning units 60, 70 each include a collection roller 62, 72 and a cleaning web 61, 71.

[0025] The recovery rollers 62, 72 are rotated by contacting the surfaces of the drive rollers 22, 32. The surfaces of the recovery rollers 62, 72 are lipophilic and have higher lipophilicity than the surfaces of the drive rollers 22, 32. Therefore, the recovery rollers 62, 72 recover the bleed components.

[0026] The bleed components collected by the collection rollers 62, 72 are removed from the collection rollers 62, 72 by the cleaning webs 61, 71. Web rollers 63, 73 come into contact with the collection rollers 62, 72 via the cleaning webs 61, 71 made of nonwoven fabric or the like. Since the collection rollers 62, 72 are rotated by the drive rollers 22, 32, the bleed components adhering to the collection roller surfaces 62, 72 are removed from the collection rollers 62, 72 by the cleaning webs 61, 71.

[0027] The cleaning units 60, 70 also include a contact / separation mechanism that allows the web rollers 63, 73 to contact and separate from the collection rollers 62, 72. The cleaning webs 61, 71 are consumables. Once the cleaning webs 61, 71 have been used to collect bleed components, they are wound up by the web take-up rollers 65, 75, and when the cleaning webs 61, 71 sent out from the web sending-out rollers 64, 74 run short, they must be replaced with new cleaning webs 61, 71. It is therefore desirable to prevent the cleaning webs 61, 71 from being wasted as much as possible. For this reason, the cleaning units perform control to bring the collection rollers 62, 72 into contact with the surfaces of the drive rollers 22, 32, and to bring the collection rollers 62, 72 into contact with the cleaning webs 61, 71. EXAMPLES

[0028] 3 is a diagram illustrating the cleaning unit 60 and the cleaning unit 70 of the embodiment 2. The cleaning unit 60 is disposed inside the upper belt unit 20, and the cleaning unit 70 is disposed inside the lower belt unit 30.

[0029] The difference from Example 1 is that there are no recovery rollers 62, 72, and the upper and lower drive rollers 22, 32 are made of metal with a rubber layer on the outside, but the material is less prone to bleeding than the rubber in Example 1. Hard silicone rubber is used in this example. Hard silicone rubber is less prone to bleeding, but because it is hard, wear powder may adhere to the inner surface of the upper belt 21 or lower belt 31 after long-term use, causing the upper belt 21 or lower belt 31 to slip.

[0030] In order to prevent such slippage, cleaning units 60 and 70 are provided. In the cleaning units 60 and 70, the cleaning web 61 can come into contact with the upper tension roller 23, and the cleaning web 71 can come into contact with the lower tension roller 33.

[0031] Wear powder adhering to the inner surface of the upper belt 21 or the inner surface of the lower belt 31 is also carried to the upper tension roller 23 which is in contact with the inner surface of the upper belt 21. Similarly, it is also carried to the lower tension roller 33 which is in contact with the inner surface of the lower belt 31. Web rollers 63, 73 abut against the tension rollers 23, 33 via cleaning webs 61, 71 made of nonwoven fabric or the like. Since the tension rollers 23, 33 are rotated by the belts 21, 31, wear powder adhering to the surfaces of the tension rollers 23, 33 is removed from the tension rollers 23, 33 by the cleaning webs 61, 71. Comparative Example 1

[0032] 4 shows a fixing device 10 in which the upper belt unit 20 and the lower belt unit 30 do not have cleaning units. Comparative Example 1 is the same as Example 1 except that there is no cleaning unit. Comparative Example 2

[0033] Comparative Example 2 is the same as Example 2, except that there is no cleaning unit.

[0034] <Evaluation of upper and lower belt speed difference during durability> A durability test was carried out using the fixing devices of the embodiment and the comparative example.

[0035] Each fixing device was placed in an idling test machine, and the fixing temperature was set to 100°C, the process speed to 700mm / sec, and the speeds of the upper belt 21 and the lower belt 31 were measured every 100 hours using a laser Doppler velocimeter (Canon LV-20Z) to compare the speed differences between the upper belt and the lower belt. Measurements were performed five times for each belt, the average of the measurement results was taken as the belt speed, and the speed differences between the upper belt and the lower belt were compared in absolute values.

[0036] In Examples 1 and 2, cleaning was performed every 20 hours of continuous rotation. However, when belt speed was measured every 100 hours, cleaning was performed after the speed measurement was completed. The cleaning was performed by bringing the cleaning web into contact with the recovery roller or tension roller using the web roller contact mechanism, with a process speed of 350 mm / sec, a cleaning web feed speed of 1 mm / sec, and a cleaning time of 60 sec. After cleaning, the cleaning web was separated by operating the web roller separation mechanism.

[0037] In Comparative Example 1 and Comparative Example 2, cleaning processing was not performed because there was no cleaning mechanism. However, similar to Examples 1 and 2, the process speed was changed every 20 hours of continuous rotation time to prevent any difference in the belt running distance between the Examples and Comparative Examples.

[0038] The durability test results are shown in Table 1. [Table 1]

[0039] <Evaluation of paper wrinkles> The fixing device that had been subjected to the durability test was used to evaluate whether or not wrinkles occurred on the paper.

[0040] In an environment of high temperature (about 30°C) and high humidity (about 80%), the fixing temperature was set to 100°C, the process speed was set to 700 mm / sec, and SRA3 size paper (product name "OK Prince Johyo 52", manufactured by Oji Paper Co., Ltd.) was used as the evaluation paper. 100 sheets were continuously passed through, and the number of sheets with paper wrinkles was compared.

[0041] The results of the paper wrinkle evaluation test are shown in Table 2. [Table 2]

[0042] <Evaluation Results> In Example 1 and Example 2, there was almost no difference in speed between the upper and lower belts, and the number of sheets with wrinkles was 0. In addition, there was no noticeable dirt on the inner surface of the upper belt 21 or the inner surface of the lower belt 31.

[0043] In Comparative Example 1 and Comparative Example 2, the difference between the upper and lower belts was observed after more than 600 hours, and at 1200 hours, the difference was about 2 mm / sec. The occurrence of paper wrinkles was confirmed. Dirt that had bled from the rubber layers of the drive rollers 22 and 32 was visually confirmed on the inner surface of the upper belt 21 and the inner surface of the lower belt 31 in Comparative Example 1. Adhesion of wear powder from the rubber layers of the drive rollers 22 and 32 was visually confirmed on the inner surface of the upper belt 21 and the inner surface of the lower belt 31 in Comparative Example 2.

[0044] In this way, the embodiment can provide a long-life image heating device that prevents dirt from adhering to the inner surface of the belt by performing regular cleaning processing, can drive the belt stably for a long period of time compared to the comparative example, and suppresses the occurrence of paper wrinkles. [Explanation of symbols]

[0045] 100 Fixing device 20 Upper belt unit 21 Upper Belt 22 Upper drive roller 23 Upper tension roller 24 Upper steering roller 30 Lower belt unit 31 Lower Belt 32 Lower drive roller 33 Lower tension roller 34 Lower steering roller 40 Upper belt heater 41 Reflector 42 Lower belt heater 50 Upper belt temperature sensor 51 Lower belt temperature sensor 60, 70 cleaning units 61, 71 Cleaning Web 62, 72 Collection roller 63, 73 Web roller 64, 74 Web feed roller 65, 75 Web winding roller

Claims

1. A fixing device including an upper belt unit including an upper belt and at least two rollers for tensioning the upper belt, and a lower belt unit including a lower belt and at least two rollers for tensioning the lower belt, A fixing device, comprising: a cleaning unit disposed inside at least one of the upper belt unit and the lower belt unit, for cleaning a member that transports the belt.

2. 2. The fixing device according to claim 1, wherein the cleaning unit is disposed on a driving member of the belt.

3. 3. The fixing device according to claim 1, wherein the cleaning unit is configured with a web member as a dirt collecting member.

4. The conveyor has at least one of an upper collection roller that is rotated by an upper driving roller that drives the upper belt and a lower collection roller that is rotated by a lower driving roller that drives the lower belt, In a configuration having a web roller that contacts the upper collection roller or the lower collection roller or both of them via a web member, 4. The fixing device according to claim 1, wherein the peripheral speed of at least the upper or lower recovery roller or both and at least one of the web rollers is slower than that of the web roller.

5. In a configuration having at least one of an upper tension roller for tensioning the upper belt and a lower tension roller for tensioning the lower belt, and having a web roller that contacts the upper tension roller or the lower tension roller or both via a web member, The fixing device according to any one of claims 1 to 3, characterized in that the peripheral speed of at least one of the upper tension roller or lower tension roller or both and at least one of the web roller or both is slower than that of the one of the web roller or both.

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