Fixing apparatus and image forming apparatus

Abstract

To provide a fixing device including a configuration that has prevented the flow of air toward a contact temperature sensor, and an image forming apparatus.SOLUTION: A fixing device 500 comprises: a cover 510 that is provided to cover a heating roller 502; and a temperature sensor 550 that is provided on the cover 510 and measures the temperature of a fixing belt 504. The cover 510 includes, near a place where the temperature sensor 550 is provided, a convex part 532 that projects toward the fixing belt 504, and an opening 532h that allows the convex part 532 to be exposed therethrough and is provided at a position separated from the fixing belt 504 when seen from the convex part 532.SELECTED DRAWING: Figure 2

Description

Technical Field

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[0001] The present invention relates to a fixing device and an image forming device using an electrophotographic method in a copying machine, a laser beam printer, a fax machine, or a multifunction device thereof.

Background Art

[0002] In a fixing device that performs fixing temperature control using a non-contact temperature sensor, it has been found that incorrect temperature detection occurs due to the influence of the wind flowing near the non-contact temperature sensor. In Japanese Patent Application Laid-Open No. 2021-124652 (Patent Document 1) below, ribs and seals are provided near the non-contact temperature sensor to suppress the inflow of wind into the non-contact sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique disclosed in Patent Document 1 above, it is difficult for wind to hit the non-contact temperature sensor. However, in recent energy-saving measures and high-image-quality measures, it is necessary to perform temperature control with high precision, and a configuration that can further suppress the flow of wind near the non-contact temperature sensor is required.

[0005] On the other hand, in a configuration with ribs and seals, when adjusting the GAP (gap) between the non-contact temperature sensor and the fixing belt, the ribs and seals get in the way, affecting the adjustment of the GAP, or touching the fixing belt during the adjustment of the GAP, which may cause the seal to bend. <00000​​This invention has been made in view of the above problems, and its main objective is to provide a fixing device and an image forming apparatus that have a configuration that can further suppress the airflow near a non-contact temperature sensor. Preferably, the invention provides a fixing device and an image forming apparatus that have a configuration that does not affect the adjustment of the GAP between the non-contact temperature sensor and the fixing belt. [Means for solving the problem]

[0007] [1] The fixing device comprises an endless fixing belt, a heating roller having a heating source for heating the fixing belt, a fixing member disposed on the inner circumference side of the fixing belt, a pressure roller that presses the fixing belt toward the fixing member and together with the fixing belt forms a fixing nip portion on which the recording medium is transported, a cover provided on the opposite side from the pressure roller as seen from the heating roller and provided to cover the heating roller, and a temperature sensor provided on the cover for measuring the temperature of the fixing belt.

[0008] The cover includes a protrusion that projects toward the fixing belt near where the temperature sensor is provided, and an opening provided at a position away from the fixing belt when viewed from the protrusion, in which the protrusion is exposed.

[0009] [2]:The fixing device described in [1], wherein the convex portion is provided such that when it intersects with the fixing belt, the angle it makes with the fixing belt is obtuse.

[0010] [3]: The fixing device according to [1] or [2], wherein the air inflow resistance of the opening is smaller than the air inflow resistance in the gap between the protrusion and the fixing belt.

[0011] [4]: A fixing device according to any one of items [1] to [3], wherein the cover comprises a main body cover on which the temperature sensor is mounted and a protective cover covering the temperature sensor, the main body cover having a main opening, the protective cover having a protrusion and an opening, and the protective cover being attached from the side of the main body cover away from the fixing belt, so that the protrusion protrudes from the main opening of the main body cover toward the fixing belt.

[0012] [5]: A fixing device according to any one of items [1] to [4], wherein the protective cover is attached to the main body cover after the mounting position for the temperature sensor has been adjusted on the main body cover.

[0013] [6]: A fixing device according to any one of items [1] to [5], wherein the protrusion is plate-shaped or sheet-shaped.

[0014] [7]: A fixing device according to any one of items [1] to [6], wherein the protrusion and the opening are provided on the upstream side of the rotation direction of the heating roller when viewed from the temperature sensor.

[0015] [8] This image forming apparatus is equipped with a fixing device as described in any one of the above items [1] to [7]. [Effects of the Invention]

[0016] This fixing device and image forming apparatus provide a configuration that can further suppress the airflow near the contact temperature sensor. [Brief explanation of the drawing]

[0017] [Figure 1] This figure shows an example of an image forming apparatus according to Embodiment 1. [Figure 2] This is an enlarged longitudinal cross-sectional view of the fixing device of Embodiment 1. [Figure 3]It is a schematic diagram showing the air flow from the fan provided in the image forming apparatus of Embodiment 1 to the fixing device. [Figure 4] It is a perspective view of the cover as viewed from the fixing belt side of Embodiment 1. [Figure 5] It is a perspective view of the cover as viewed from the side opposite to the fixing belt of Embodiment 1. [Figure 6] It is a perspective view of the main body cover as viewed from the side opposite to the fixing belt of Embodiment 1. [Figure 7] It is a perspective view of only the protective cover as viewed from the fixing belt side of Embodiment 1. [Figure 8] It is a perspective view of only the protective cover as viewed from the side opposite to the fixing belt of Embodiment 1. [Figure 9] It is an enlarged longitudinal sectional view of the fixing device of Embodiment 2. [Figure 10] It is a perspective view of the cover as viewed from the fixing belt side of Embodiment 2. [Figure 11] It is a perspective view of only the protective cover as viewed from the fixing belt side of Embodiment 2.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, the image forming apparatus of each embodiment will be described with reference to the drawings. In each of the embodiments described below, when referring to the number, amount, etc., unless otherwise specified, the scope of the present invention is not necessarily limited to the number, amount, etc. The same parts and corresponding parts are given the same reference numerals, and redundant explanations may not be repeated.

[0019] <Embodiment 1: Outline of Image Forming Apparatus 1> FIG. 1 is a diagram showing an example of the image forming apparatus 1. Referring to FIG. 1, the outline of the hardware configuration of the image forming apparatus 1 will be described. The image forming apparatus 1 includes a print engine 100, a reading unit 200, and an operation panel 300.

[0020] The print engine 100 comprises an imaging unit 110, an intermediate transfer belt 120, a fixing device 500, a paper feed unit 140, a delivery roller 150, a transport roller 160, a registration roller 170, a control unit 180, and a power supply unit 190.

[0021] The print engine 100 performs printing on the recording medium (paper, sheet-like material, etc.) in the paper feeding unit 140. The delivery roller 150 transports the recording medium from the paper feeding unit 140. Furthermore, the transport roller 160 transports the recording medium in the direction of the intermediate transfer belt 120.

[0022] The imaging unit 110 includes imaging units 10C, 10M, 10Y, and 10K that form toner images of cyan (C), magenta (M), yellow (Y), and key plate (K), respectively. Each imaging unit 10C, 10M, 10Y, and 10K includes a charging unit (not shown), a developing unit (not shown), a cleaning unit (not shown), and an intermediate transfer contact roller (not shown).

[0023] The imaging unit 10C includes a photoreceptor 11C. The imaging unit 10M includes a photoreceptor 11M. The imaging unit 10Y includes a photoreceptor 11Y. The imaging unit 10K includes a photoreceptor 11K. Hereinafter, the photoreceptors 11C, 11M, 11Y, and 11K may be collectively referred to simply as "photoreceptors."

[0024] The exposure unit 112 is common to imaging units 10C, 10M, 10Y, and 10K. Each of the imaging units 10C, 10M, 10Y, and 10K may include its own separate exposure unit 112. In the following description, it will be assumed that the exposure unit 112 is common to each of the imaging units 10C, 10M, 10Y, and 10K.

[0025] The imaging unit 110 and the intermediate transfer belt 120 form a toner image to be transferred to the recording medium. The charging unit uniformly charges the surface of the photoreceptor. The exposure unit 112 exposes the surface of the photoreceptor according to a specified image pattern by laser writing or the like, thereby forming an electrostatic latent image on its surface. The developing unit develops the electrostatic latent image formed on the photoreceptor as a toner image.

[0026] The registration roller 170 adjusts the transport timing of the recording medium before it reaches the intermediate transfer belt 120. The intermediate transfer belt 120 transfers the toner image onto the recording medium. The fuser unit 500 performs the fixing process on the recording medium. Finally, the recording medium is discharged into the output tray. The detailed structure of the fuser unit 500 will be described later.

[0027] The toner image formed on the surface of the photoreceptor is transferred to the intermediate transfer belt 120 by the intermediate transfer contact roller. The toner images are sequentially transferred from each photoreceptor onto the intermediate transfer belt 120, and the four colored toner images are superimposed. The superimposed toner images are then transferred from the intermediate transfer belt 120 to the recording medium.

[0028] The reading unit 200 reads character information and other data on the sheet and outputs the reading result as an input image to the print engine 100. The image scanner 210 scans the sheet placed on the platen glass and transmits the generated image data to the control unit 180. The automatic document feeder 220 continuously scans the sheets placed on the paper feed tray 230.

[0029] Sheets placed on the paper feed tray 230 are fed one by one by a feed roller (not shown) and scanned sequentially by an image sensor located in the image scanner 210 or automatic document feeder 220. After scanning, the sheets are discharged to the output tray 240.

[0030] The control unit 180 controls the entire image forming apparatus 1. The power supply unit 190 is connected to an AC power source and supplies power to the image forming apparatus 1. The power supply unit 190 includes a rectifier circuit and can convert the AC supplied from the AC power source into DC and supply DC current to some or all of the circuits in the image forming apparatus 1.

[0031] The control panel 300 includes a display unit (not shown) and an operation unit (not shown). The display unit includes a liquid crystal monitor, an organic EL (Electro Luminescence) monitor, etc. The liquid crystal monitor, organic EL monitor, etc., includes a touch sensor and can display an operation menu and accept touch input from the user. The operation unit includes multiple buttons and can accept input from the user in the same way as the touch panel. The control panel 300 transmits the received input to the control unit 180.

[0032] <Fusing device 500> The configuration of the fixing device 500 will be described with reference to Figures 2 and 3. Figure 2 is an enlarged longitudinal cross-sectional view of the fixing device 500, and Figure 3 is a schematic diagram showing the airflow from the fan 400 provided in the image forming apparatus 1 to the fixing device 500.

[0033] The fixing device 500 includes an endless fixing belt 504, a heating roller 502 having a heating heater 502h inside as a heat source for heating the fixing belt 504, a fixing pad 506 positioned on the inner circumference side of the fixing belt 504, and a pressure roller 501 that presses the fixing belt 504 toward the fixing pad 506, forming a fixing nip section n1 together with the fixing belt 504 on which the recording medium is transported. In this embodiment, a pad-type member is used for the fixing pad 506, but a roller-type fixing member may also be used as the fixing member. The same applies hereafter.

[0034] To transport the recording medium P in the direction F in the figure, the pressure roller 501 rotates in the direction of arrow A in the figure, and the fixing belt 504 and heating roller 502 rotate in the direction of arrow B in the figure. The fixing belt 504, fixing pad 506, heating roller 502, and pressure roller 501 are arranged to extend perpendicular to the paper plane in Figure 2.

[0035] On the opposite side of the heating roller 502 from the pressure roller 501, a cover 510 is provided to cover the heating roller 502. A temperature sensor 550 for measuring the temperature of the fixing belt 504 is provided in a predetermined position on this cover 510. Preferably, a non-contact temperature sensor is used for the temperature sensor 550.

[0036] The heating roller 502 is heated by a heating heater 502h, and the control unit 180 controls the temperature based on temperature information obtained from the temperature sensor 550. The pressure roller 501 is driven to rotate in the direction of arrow A in the figure, and drives the fixing belt 504 to rotate in the direction of arrow B in the figure. An unfixed toner image, shown by the dashed line in the figure, is formed on the recording medium P. The recording medium P is transported in the direction of arrow F in the figure, and the unfixed toner image is fixed to the recording medium P at the fixing nip section n1, which is sandwiched between the pressure roller 501 and the fixing pad 506.

[0037] The temperature sensor 550 measures the temperature of the fixing belt 504, which is the object being measured, while maintaining a constant distance from it. The airflow from the fan 400 provided in the image forming apparatus 1 to cool the pressure roller 501 of the fixing device 500 is discharged to the outside of the fixing device 500 through a duct 570 provided inside the fixing device 500. However, some of the airflow is drawn into the fixing device 500 by the airflow generated by the rotation of the fixing belt 504.

[0038] Air is generated on the surface of the fixing belt 504 in the direction of arrow B, and as described above, the relatively strong airflow drawn into the fixing device 500 may reach the temperature sensor 550 and cool it. As a result, the temperature of the fixing belt 504 cannot be accurately measured when the airflow does not reach the temperature sensor 550, and the temperature sensor 550 detects a temperature lower than the actual temperature of the fixing belt 504. Consequently, the operating time of the heating heater 502h may be prolonged.

[0039] Therefore, in this embodiment, the cover 510 is configured to suppress wind in the direction of arrow B from hitting the temperature sensor 550. The cover 510 includes a protrusion 532 that projects toward the fixing belt 504 near where the temperature sensor 550 is located, and an opening 532h that is provided at a position away from the fixing belt 504 when viewed from the protrusion 532, exposing the protrusion 532. The protrusion 532 is preferably provided such that when it intersects with the fixing belt 504, the angle (α) it makes with the fixing belt 504 is obtuse.

[0040] Referring to Figure 3, by providing the cover 510 having the above configuration, the air flowing over the surface of the pressure roller 501 and the air flowing over the surface of the fixing belt 504 (arrow B1 in the figure) are separated by the protrusion 532 that projects toward the fixing belt 504, and most of the air is guided to an opening 532h provided at a position away from the fixing belt 504 when viewed from the protrusion 532, and the air is released outside the cover 510 from this opening 532h. Furthermore, by setting the angle (α) between the protrusion 532 and the fixing belt 504 to be obtuse, it is possible to allow air to flow smoothly from the fixing belt 504 toward the protrusion 532.

[0041] Here, it is preferable that the airflow resistance at the opening 532h (dimension S2 in Figure 2) is smaller than the airflow resistance at the gap between the protrusion 532 and the fixing belt 504 (dimension S1 in Figure 2). This encourages the airflow on the surface of the fixing belt 504 to be diverted towards the opening 532h.

[0042] As a result, the airflow over the surface of the fixing belt 504 is diverted towards the opening 532h, reducing the airflow towards the temperature sensor 550 and suppressing contact of the airflow with the temperature sensor 550. This allows the temperature of the fixing belt 504 to be accurately measured by the temperature sensor 550, and enables optimization of the operating time of the heating element 502h.

[0043] The detailed structure of the cover 510 will be described with reference to Figures 4 to 8. Figure 4 is a perspective view of the cover 510 as seen from the fixing belt 504 side, Figure 5 is a perspective view of the cover 510 as seen from the opposite side of the fixing belt 504, Figure 6 is a perspective view of the main body cover 520 as seen from the opposite side of the fixing belt 504, Figure 7 is a perspective view of only the protective cover 530 as seen from the fixing belt 504 side, and Figure 8 is a perspective view of only the protective cover 530 as seen from the opposite side of the fixing belt 504.

[0044] In Figures 4 to 8, a cover 510 is provided to cover the heating roller 502 along the direction in which the rotation axis of the heating roller 502 extends. However, the entire cover 510 is not shown; only the area around the temperature sensor 550, which is provided on one end of the heating roller 502, is illustrated. The temperature sensor 550 is similarly provided on the other end of the heating roller 502.

[0045] Referring to Figures 4 and 5, the cover 510 includes a main body cover 520 on which the temperature sensor 550 is mounted, and a protective cover 530 that covers the temperature sensor 550.

[0046] Referring to Figure 6, the main body cover 520 is provided to cover the heating roller 502 along the direction in which the rotation axis of the heating roller 502 extends. The main body cover 520 is provided with a rectangular main opening 520h. The temperature sensor 550 is positioned and fixed using a position adjustment screw 523 with shims or the like interposed (not shown) on a temperature sensor mounting plate 522 that extends inward from the edge of this main opening 520h. Specifically, the position of the temperature sensor 550 is precisely adjusted so that the distance (gap) from the temperature sensor 550 to the fixing belt 504 is a predetermined dimension.

[0047] Referring to Figures 7 and 8, the protective cover 530 has a protective cover body 531 that covers the heating roller 502 along the direction in which the rotation axis of the heating roller 502 extends. The protective cover body 531 is provided with a protrusion 532 that projects toward the fixing belt 504 side from the protective cover body 531 at a position corresponding to the main opening 520h. The protrusion 532 has a flat plate shape, and its width (W) in the rotation axis direction of the heating roller 502 is set to a size that can accommodate it in the main opening 520h. The protrusion 532 is positioned upstream of the rotation direction of the heating roller 502 when viewed from the temperature sensor 550.

[0048] Furthermore, the protective cover body 531 has a protrusion 532 exposed, and an opening 532h is provided in a direction away from the fixing belt 504 when viewed from the protrusion 532.

[0049] Referring again to Figures 4 and 5, after the mounting position of the temperature sensor 550 on the main body cover 520 has been adjusted, the protective cover 530 is attached to the main body cover 520. As a result, the protrusion 532 of the protective cover 530 protrudes from the main opening 520h of the main body cover 520 toward the fixing belt 504. The temperature sensor 550 is now covered by the protective cover 530.

[0050] In this case, by configuring the protective cover 530 to be attached from the opposite side of the fixing belt 504 of the main body cover 520, the position of the temperature sensor 550 relative to the fixing belt 504 can be accurately adjusted in advance, thereby improving the accuracy of adjusting the temperature sensor's gap between the temperature sensor 550 and the fixing belt 504. Furthermore, it is possible to prevent the temperature sensor 550 from touching the fixing belt 504 when adjusting the gap between the temperature sensor 550 and the fixing belt 504.

[0051] Furthermore, the airflow resistance at the opening 532h (dimension S2 in Figure 2) is set to be smaller than the airflow resistance at the gap between the protrusion 532 and the fixing belt 504 (dimension S1 in Figure 2). As a result, the airflow over the surface of the fixing belt 504 is more easily diverted towards the opening 532h.

[0052] By using the cover 510 having the above configuration, as shown in Figure 3, when viewed from the temperature sensor 550, the protrusion 532 and the opening 532h are provided on the upstream side in the rotational direction of the heating roller 502. As a result, the air flowing over the surface of the pressure roller 501 and the air flowing over the surface of the fixing belt 504 (arrow B1 in the figure) are diverted by the protrusion 532 that protrudes toward the fixing belt 504 before reaching the temperature sensor 550, and a large portion of this air is guided to the opening 532h provided on the upstream side in the rotational direction of the fixing belt 504, and the air is released to the outside of the cover 510 from this opening 532h.

[0053] As a result, the airflow towards the temperature sensor 550 is reduced, and contact of air with the temperature sensor 550 is suppressed. Consequently, the temperature detection accuracy of the fixing belt 504 by the temperature sensor 550 is improved, and the control unit 180 of the image forming apparatus 1 can optimize the operating time of the heating heater 502h of the fixing device 500.

[0054] <Embodiment 2: Fixing device 500A> Next, with reference to Figures 9 to 11, the fixing device and image forming apparatus in Embodiment 2 will be described below. Figure 9 is an enlarged vertical cross-sectional view of the fixing device 500A, Figure 10 is a perspective view of the cover 510 as seen from the fixing belt 504 side, and Figure 11 is a perspective view of only the protective cover 530 as seen from the fixing belt 504 side.

[0055] The basic configuration of the fixing device 500A in this embodiment is the same as that of the fixing device 500 in Embodiment 1 described above. The difference is that in the fixing device 500A, a sheet member 560 is provided that further protrudes toward the fixing belt 504 on the protrusion 532 that protrudes toward the fixing belt 504 provided on the protective cover 530. The sheet member 560 may be made of an elastically deformable sheet-like rubber material or the like. The sheet member 560 is fixed to the protrusion 532 using an adhesive or the like.

[0056] The gap (S4) between the sheet member 560 and the fixing belt 504 can be set to a size that prevents the sheet member 560 from coming into contact with the fixing belt 504. Furthermore, even if the sheet member 560 does come into contact with the fixing belt 504, the sheet member 560 will elastically deform, preventing damage to the fixing belt 504.

[0057] As described above, the fixing device 500A of this embodiment and the image forming apparatus 1 using it can achieve the same effects and advantages as the fixing device 500 and the image forming apparatus 1 using it of Embodiment 1.

[0058] In the above embodiment, a configuration was described in which a protrusion 532 and an opening 532h are provided on the protective cover 530, and the protective cover 530 is attached to the main body cover 520. However, the configuration is not limited to this. For example, even if the protrusion 532 and the opening 532h are directly provided on the main body cover 520, the protrusion 532 and the opening 532h will be provided on the upstream side in the rotation direction of the heating roller 502 when viewed from the temperature sensor 550, so it is possible to obtain the same effects as the above configuration.

[0059] Although the fixing apparatus and image forming apparatus have been described above based on each embodiment, the embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are included. [Explanation of symbols]

[0060] 1 Image forming apparatus, 10C, 10K, 10M, 10Y, 110 Imaging unit, 11C, 11K, 11M, 11Y Photoreceptor, 100 Print engine, 112 Exposure unit, 120 Intermediate transfer belt, 500, 500A Fixing unit, 140 Paper feed unit, 150 Delivery roller, 160 Transport roller, 170 Register roller, 180 Control unit, 190 Power supply unit, 200 Reading unit, 210 Image scanner, 220 Automatic document feeder, 230 Paper feed tray, 240 Paper output tray, 300 Operation panel, 400 Fan, 501 Pressure roller, 502 Heating roller, 502h Heating heater, 504 Fixing belt, 506 Fixing pad, 510 Cover, 520 Main unit cover, 520h Main opening, 522 Temperature sensor mounting plate, 523 Position mounting adjustment screw, 530 Protective cover, 531 Protective cover body, 532 Protrusion, 532h Opening, 550 Temperature sensor, 560 Sheet material, 570 Duct, n1 Fixing nip part.

Claims

1. An endless fixing belt, A heating roller having a heating source for heating the fixing belt, A fixing member positioned on the inner circumference side of the fixing belt, A pressure roller presses the fixing belt toward the fixing member, and together with the fixing belt, forms a fixing nip section on which the recording medium is transported. A cover is provided on the opposite side from the heating roller, as viewed from the heating roller, and is provided so as to cover the heating roller. A temperature sensor is provided in the cover for measuring the temperature of the fixing belt, Equipped with, The aforementioned cover is Near where the temperature sensor is provided, there is a protrusion that extends toward the fixing belt, An opening is provided where the aforementioned protrusion is exposed and is located away from the fixing belt when viewed from the aforementioned protrusion, Includes, The aforementioned cover is The main body cover on which the temperature sensor is attached, The temperature sensor has a protective cover, The main body cover is provided with a main opening, The protective cover is provided with the protrusion and the opening, By attaching the protective cover from the side of the main body cover opposite to the fixing belt, the protrusion protrudes from the main opening of the main body cover toward the fixing belt. Fixing device.

2. The aforementioned protrusion is, The device is designed such that when it intersects with the aforementioned fixing belt, the angle it makes with the fixing belt is obtuse. The fixing device according to claim 1.

3. The air inflow resistance at the opening is smaller than the air inflow resistance at the gap between the protrusion and the fixing belt. The fixing device according to claim 1.

4. After the mounting position for the temperature sensor on the main body cover has been adjusted, the protective cover is attached to the main body cover. The fixing device according to claim 1.

5. The aforementioned protrusion is plate-shaped or sheet-shaped. The fixing device according to claim 1.

6. When viewed from the aforementioned temperature sensor, The protrusion and the opening are provided on the upstream side in the rotational direction of the heating roller. The fixing device according to claim 1.

7. An image forming apparatus comprising a fixing device according to any one of claims 1 to 6.

Images