Fixing device and image forming apparatus

Abstract

To provide a fixing device that can efficiently and effectively detect the remaining amount of a cleaning web without using a special cleaning web but using single detection means.SOLUTION: A fixing device comprises a fixing member 30 and a pressure member 31 that forms a fixing nip part N at a portion between the pressure member and the fixing member 30, and fixes a toner image to a recording medium P. The fixing device comprises cleaning means 122 that removes a residual toner attached to a surface of the fixing member 30. The cleaning means 122 includes a cleaning web 41 that sweeps off the surface of the fixing member 30, a web holding member 44, a take-up member 46, a pressing member 45, and single detection means that detects the remaining amount of the cleaning web 41 held by the web holding member 44. The detection means has a filler 40 that is displaced according to the remaining amount of the cleaning web 41 and a sensor 42 that detects the filler 40, and detects a web near-end state and a web end state.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a fixing device and an image forming apparatus.

Background Art

[0002] Conventionally, as a fixing device of an image forming apparatus, a recording medium (paper) carrying a toner image is passed through a fixing nip formed by a fixing member having a heating means and a pressing member, and heat and pressure are applied to fix the toner image on the recording medium. Such a device is known. Also known is a configuration in which a cleaning web configured to be wound up is pressed against the surface of the fixing member, and means for cleaning the surface of the fixing member is provided.

[0003] As the cleaning means, for example, a configuration is known that includes a web holding member to which the end of the cleaning web is fixed, a winding member to which the tip of the cleaning web is fixed and that rotates to wind up the cleaning web, and a pressing member that presses the cleaning web against the fixing member. By winding up the cleaning web with the winding member, the surface of the fixing member can be wiped with a new web fed out from the web holding member. Therefore, the cleaning function for the fixing member is performed well without deteriorating over time.

[0004] In such a cleaning device, there is known a mechanism that detects the remaining amount or the usage amount of the cleaning web wound around the web holding member and warns to replace it with a new cleaning web when the remaining amount is small (see, for example, Patent Document 1).

[0005] If the operation of the device is continued with the remaining amount of the cleaning web insufficient, there is a risk of deterioration of image quality and problems such as damage to the drive motor and gears. Also, if printing is continued after the warning for cleaning web replacement is displayed, there is a risk that the cleaning web will run out completely and the device will stop urgently due to an error. Regarding the remaining amount of the cleaning web, it is required to be able to detect respectively the web near-end state where the cleaning web is about to run out and the web end state where the cleaning web has run out.

[0006] To address such problems, the device in Patent Document 1 discloses a configuration in which a notch indicating the remaining amount provided on the cleaning web (fixing web) is detected by a web remaining amount detection sensor. It is described that by being able to display a predetermined remaining copy number corresponding to the notch, an operator can perform web replacement at an appropriate timing.

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the device of Patent Document 1, it is necessary to use a cleaning web in which notches corresponding to the remaining copy number are formed. Therefore, there are problems in terms of the cost of consumables. Also, it is necessary to accurately arrange a sensor at a position where the notches can be detected, and there is a problem that it is not easy to obtain sufficient detection efficiency and detection effect with a single detection means.

[0008] Therefore, an object of the present invention is to provide a fixing device that can efficiently and effectively detect the remaining amount of the cleaning web without using a special cleaning web and by a single detection means.

Means for Solving the Problems

[0009] In order to solve the above problems, a fixing device of the present invention includes a fixing member which is a rotating body heated by heating means, and a pressing member which forms a fixing nip portion between the fixing member, and conveys a recording medium carrying an unfixed toner image to the fixing nip portion to fix the toner image on the recording medium, and includes cleaning means for removing residual toner attached to the surface of the fixing member, the cleaning means includes a cleaning web for wiping the surface of the fixing member, a web holding member for holding the cleaning web so as to be feedable, a winding member for winding up the cleaning web, a pressing member for pressing the cleaning web against the fixing member, and a single detecting means for detecting the remaining amount of the cleaning web held by the web holding member, the detecting means has a filler that is displaced according to the remaining amount of the cleaning web and a sensor for detecting the filler, and respectively detects a web near end state where the cleaning web is about to run out and a web end state where the cleaning web has run out and the sensor of the detection means is turned off when there is a sufficient amount of the cleaning web held by the web holding member, turned on in the web near-end state, and turned off again in the web end state characterized by.

Effect of the Invention

[0010] According to the present invention, it is possible to provide a fixing device that can efficiently and effectively detect the remaining amount of a cleaning web without using a special cleaning web and by a single detecting means.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0012] Hereinafter, the fixing device and the image forming apparatus of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments shown below, and can be changed within the scope that those skilled in the art can conceive, such as other embodiments, additions, modifications, deletions, etc., and as long as the functions and effects of the present invention are achieved in any aspect, it is included in the scope of the present invention.

[0013] 〔Image Forming Apparatus〕 An embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. 1. FIG. 1 is a schematic configuration diagram showing an image forming apparatus, specifically a copying and printing machine capable of forming monochrome images. It also functions as a printer by connecting to a PC.

[0014] Since the image forming apparatus of this embodiment is a copying machine, it has a document reading unit that functions as a scanner. However, when a controller is built in a PC online output dedicated machine, a so-called printer version, etc., the document reading unit may be omitted.

[0015] Hereinafter, the schematic configuration and operation of the image forming apparatus of this embodiment will be described. The image forming apparatus has a scanner that houses a lighting device, an optical system, a CCD image sensor, etc. inside. Above the scanner, an automatic document reading device (hereinafter referred to as "ADF unit" (ADF: Auto Document Feeder)) 100 is provided. The ADF unit 100 automatically conveys the document and sends the document to the reading surface of the contact glass.

[0016] The operator sets the document on the ADF unit 100 integrated with the pressure plate, selects the mode using the function selection keys on the operation panel, and while checking the display content on the liquid crystal screen, operates the numeric keypad, function keys, etc. to set the desired image forming conditions.

[0017] The image signal read by the document reading unit 102 is A / D (Analog / Digital) converted by the SBU (Sensor Board Unit), and then irradiated as laser light from the laser writing unit 107. The laser light is condensed by the cylinder lens of the laser writing unit 107, line scanned in the main scanning direction by the polygon mirror, and an electrostatic latent image is formed on the photosensitive drum 108.

[0018] The developing unit 110 is provided with a drum cleaning unit 105 and a charging charger 106 around the photosensitive drum 108. The charging charger 106 is used for charging the photosensitive drum 108. A high voltage is applied to the charging charger 106 from the PSU (Power Supply Unit) via a receptacle, electrode terminals, conductive bearings, etc.

[0019] The toner supplied from the toner supply unit 109 as needed and the developer previously filled in the developing unit 110 are carried to the developing roller while being stirred and mixed by the internal conveying screw. The toner electrostatically adsorbed by the magnetic force is negatively charged.

[0020] The two-component developer carried on the developing roller is regulated to an appropriate amount by a developer standing regulation member such as a doctor blade and a casing disposed below the developing roller, and then the triboelectrically charged toner in the two components moves onto the photosensitive drum 108 according to the bias voltage and selectively adheres according to the electrostatic latent image.

[0021] The toner concentration inside the developing unit 110 is detected from its charge amount by a toner concentration sensor disposed at the bottom surface position. The toner that remains untransferred on the photoreceptor drum 108 after transfer is scraped off by a cleaning blade provided in the drum cleaning unit 105 and conveyed and collected into the waste toner bottle 119.

[0022] Also, around the developing unit 110, an inlet seal made of a mylar or sponge-like material for preventing toner scattering is appropriately provided.

[0023] The toner image formed on the photoreceptor drum 108 is first transferred onto the intermediate transfer belt unit 113. The recording medium conveyed by the paper transport unit 114 and passing through the resist roller unit is transferred with the toner on the intermediate transfer belt unit 113 due to the positive charging from the transfer unit when passing through the nip between the photoreceptor drum 108 and the intermediate transfer belt unit 113.

[0024] The recording medium (paper) onto which the toner has been transferred is conveyed to the fixing device (fixing unit) 121, and a certain temperature and pressure are applied to thermally fuse the toner image. A thermistor is provided on the fixing roller in the fixing device 121 to detect the surface temperature and perform ON / OFF control of the heater. The thermistor may be of a contact type or a non-contact type. Also, a temperature fuse is provided to prevent overheating.

[0025] The fixing device 121 of this embodiment includes at least a fixing member (fixing roller), a heating means, and a pressurizing member. The pressurizing member (pressurizing roller) is, for example, a hollow member that rotates in contact with the fixing member to form a fixing nip portion. The pressurization and depressurization of the fixing nip portion are controlled by a cam. The inside of the pressurizing member may be provided with a heating member. Note that other configurations of the fixing device 121 will be described later.

[0026] After the recording medium on which the toner image is thermally fused is separated from the heating member and the fixing member by the fixing separation plate, it is discharged to the paper output tray 125 after passing through the reverse paper output unit 120 or after double-sided printing according to the set conditions. When a post-processing device or the like is connected, it is conveyed to the recording medium inlet of the connected device. In addition, the image forming apparatus includes main body moving casters 124.

[0027] The image forming apparatus of the present embodiment performs electrophotographic image formation by the above-described configuration and operation.

[0028] 〔Fixing device〕 Next, the configuration of the fixing device 121 according to the present invention will be described with reference to FIGS. 2 to 4. The fixing device 121 of the present embodiment is mounted so as to be pullable out of the image forming apparatus shown in FIG. 1. The fixing device 121 of the present embodiment includes a fixing member (fixing roller) 30, a pressing member (pressing roller) 31 that abuts on the fixing member 30 to form a fixing nip portion, and a separation unit 13 having a separation member that separates the recording medium (paper) P after the toner image is fixed.

[0029] Schematic perspective views of the appearance of the fixing device 121 are shown in FIGS. 2 and 3. FIG. 2 shows a state in which the separation unit 13 is fixed in the closed position, and FIG. 3 shows a state in which the separation unit 13 is completely opened.

[0030] The fixing device 121 of the present embodiment includes a fixing member 22. In a conventional fixing device, a coil spring or the like is provided as an opening / closing auxiliary member 25 so that the separation unit 13 does not fall due to its own weight, and the weight balance during opening and closing is maintained by the tension thereof. However, if the tension of the coil spring is insufficient, the holding force is also insufficient, and the separation unit 13 may fall due to its own weight. On the other hand, the fixing device 121 of the present embodiment can fix the separation unit 13 at a desired position between the open position and the closed position by the fixing member 22, and can prevent the separation unit 13 from accidentally falling or moving.

[0031] In the fixing device 121 of the present embodiment, the operation for swinging and rotating the separation unit 13 to open and close is performed by manually moving the fixing member 22 and the operation knob 23. First, while pressing the biasing member 26 and sliding the fixing member 22 with the left hand, raise the operation knob 23 to the position 23a (see FIG. 2) with the right hand to release the lock, and the separation unit 13 can be opened and closed.

[0032] FIG. 4 is a schematic diagram showing an example of the configuration of the fixing device 121 according to the present invention. The fixing device 121 of the present embodiment includes a fixing member 30 which is a rotating body heated by heating means, and a pressing member 31 which forms a fixing nip portion N between the fixing member 30. The fixing device conveys a recording medium P carrying an unfixed toner image to the fixing nip portion N and fixes the toner image on the recording medium P. Further, it is provided with a cleaning means 122 for removing residual toner adhering to the surface of the fixing member 30. The cleaning means 122 includes a cleaning web 41 for wiping the surface of the fixing member 30, a web holding member 44 for holding the cleaning web 41 so as to be able to feed it out, a winding member 46 for winding up the cleaning web 41, a pressing member 45 for pressing the cleaning web 41 against the fixing member 30, and a single detecting means for detecting the remaining amount of the cleaning web 41 held by the web holding member 44. The single detecting means has a filler 40 that is displaced according to the remaining amount of the cleaning web 41 and a sensor 42 that detects the filler 40, and respectively detects a web near-end state where the cleaning web is about to run out and a web end state where the cleaning web has run out.

[0033] The toner melted in the fixing nip portion N does not all fix to the recording medium P after passing through the fixing nip portion N, but a part of it adheres to the surface of the fixing member 30 and moves as the fixing member 30 rotates. There was a problem that the toner transferred to the fixing member 30 adhered to the pressing member 31 in contact with the fixing member 30, the recording medium P to be passed through next, etc., and soiled them. In order to prevent this problem, the fixing device 121 of the present embodiment is provided with cleaning means 122 for cleaning the toner adhering to the surface of the fixing member 30.

[0034] The cleaning means 122 includes a cleaning web 41 for wiping the surface of the fixing member 30, a web holding member 44, a winding member 46, and a pressing member 45. As the cleaning web 41, a known one can be used as long as it is a long one capable of wiping the residual toner on the surface of the fixing member 30. For example, non-woven fabric etc. can be mentioned. Specifically, it is a fiber sheet, a web, etc., in which the fibers are oriented in one direction or randomly, and the fibers are bonded by alternating current, and / or fusion, and / or adhesion. Examples of natural fibers include cotton, wool, hemp, pulp, silk, etc., and examples of chemical fibers include rayon, nylon, polyester, polypropylene, acrylic fiber, vinylon, aramid fiber, etc. The winding member 46 is driven by a drive motor 43 and rotates in the winding direction, so that the unused portion of the cleaning web 41 (the portion not in contact with the fixing member 30) is sent out from the side of the web holding member 44 and moves. By continuing the cleaning operation, the diameter of the roll-shaped cleaning web 41 wound around the web holding member 44 decreases, and the diameter of the roll-shaped cleaning web 41 wound around the winding member 46 increases.

[0035] One end of the filler 40 that is displaced according to the remaining amount of the cleaning web 41 abuts on the outer peripheral surface of the cleaning web 41 wound around the web holding member 44, and is displaced as the remaining amount of the unused cleaning web 41 changes, that is, as the roll diameter changes. The displacement of the filler 40 is, for example, rotation about a fulcrum.

[0036] Based on FIGS. 5 to 8, the positional relationship between the remaining amount of the cleaning web 41 and the detection means will be described. FIGS. 5 to 8 are explanatory views schematically showing the cleaning means 122. In each of the figures, (a) is a cross-sectional view (structural side view) on the side of the cleaning web 41, and (b) is a rear-side structural side view when (a) is on the front side of the side plate 50. In each of the figures (b), the outer periphery of the cleaning web 41 wound around the web holding member 44 and the portion of the filler 40 that cannot be visually recognized are shown by broken lines.

[0037] As shown in FIGS. 5 to 8, the filler 40 of the detection means is a member having a contact portion 40a that contacts the outer peripheral surface of the cleaning web 41 wound around the web holding member 44 and a detected portion 40b that is detected by the sensor 42, and rotates and displaces about the fulcrum 40c.

[0038] As the sensor 42, a known sensor can be used as long as it can detect the displaced filler 40. For example, an optical sensor that uses light to detect the presence or position of an object (filler 40) can be mentioned. As the optical sensor, a transmissive photointerrupter or a reflective photoreflector is preferable. The photointerrupter is a sensor in which a light emitting portion and a light receiving portion are arranged to face each other, and the light receiving portion detects that the detected portion 40b of the filler passing through blocks the light from the light emitting portion. The photoreflector is a sensor that reflects the light from the light emitting portion by the detected portion 40b of the filler and detects the reflected light by the light receiving portion.

[0039] FIGS. 5(a) and 5(b) show the positional relationship between the filler 40 and the sensor 42 when the cleaning web 41 is new (the ratio of the unused cleaning web is 100%). When there is a sufficient remaining amount of the cleaning web 41 wound around the web holding member 44, the contact portion 40a of the filler contacts the outer periphery 41a, and the detected portion 40b of the filler is located away from the sensor 42, so the sensor 42 is "detection off".

[0040] Figures 6(a) and 6(b) show the positional relationship between the filler 40 and the sensor 42 when the cleaning web 41 is in the web near-end state (the proportion of the unused cleaning web is about 20%). In the web near-end state where the remaining amount of the cleaning web 41 wound around the web holding member 44 is small and the cleaning web is about to run out, the contact portion 40a of the filler contacts the outer periphery 41b. By rotating around the fulcrum 40c from the position where it was in contact with the outer periphery 41a in FIG. 5, the detected portion 40b of the filler is displaced to a position where it is detected by the sensor 42, and the sensor 42 becomes "detection on".

[0041] Figures 7(a) and 7(b) show the positional relationship between the filler 40 and the sensor 42 when the cleaning web 41 is in the web end state (the proportion of the unused cleaning web is about 2 - 3%). In the web end state where the remaining amount of the cleaning web 41 wound around the web holding member 44 is almost zero and the cleaning web has run out, the contact portion 40a of the filler contacts the outer periphery 41c. By further rotating around the fulcrum 40c from the position where it was in contact with the outer periphery 41b in FIG. 6, the detected portion 40b of the filler is displaced to a position where it is not detected by the sensor 42, and the sensor 42 becomes "detection off" again.

[0042] Figures 8(a) and 8(b) show the positional relationship between the filler 40 and the sensor 42 when the proportion of the unused cleaning web 41 is 0%. There is no remaining amount of the cleaning web 41 wound around the web holding member 44, and the contact portion 40a of the filler contacts the mandrel 41d of the web holding member 44. Although it further rotates around the fulcrum 40c from the position where it was in contact with the outer periphery 41c in FIG. 7, the detected portion 40b of the filler is in a position where it is not detected by the sensor 42, and the sensor 42 continues to be in the "detection off" state.

[0043] As shown in FIGS. 5 to 8, in the cleaning means included in the fixing device of the present embodiment, the sensor 42 of the detection means is off when there is a sufficient remaining amount of the cleaning web 41 held by the web holding member 44, on in the web near-end state, and off again in the web end state.

[0044] The filler 40 is not detected by the sensor 42 when there is a sufficient remaining amount of the cleaning web 41, is displaced to a position where it is detected by the sensor 42 in the web near-end state, and is displaced to a position where it is not detected by the sensor 42 in the web end state.

[0045] That is, by determining that the signals when the detected portion 40b of the single filler 40 is before, during, and after passing through the single sensor 42 are in the state where the remaining amount of the cleaning web 41 is sufficient, the web near-end state, and the web end state, respectively, the remaining amount of the cleaning web can be efficiently and effectively detected by a single detection means without using a special cleaning web.

[0046] As shown in FIG. 4, the fixing device of the present embodiment includes a drive motor 43 of the winding member 46 and a control means 11. Furthermore, it may be configured to further include means for detecting a change in the current value associated with the torque fluctuation of the drive motor 43, calculate the amount of the cleaning web 41 wound around the winding member 46 from the change in the current value, and compare it with the state of the remaining amount of the cleaning web 41 detected by the detection means (sensor 42).

[0047] By comparing the torque fluctuation of the drive motor 43 with the detection result by the sensor 42, the detection accuracy of the remaining amount of the cleaning web 41 can be further improved.

[0048] The current value associated with the torque fluctuation of the drive motor 43 is preferably corrected by at least one of temperature conditions, the value of the power supply voltage, and the horizontal state of the device.

[0049] Alternatively, when replacing the cleaning web 41 with a new one, initialization may be performed, the current value immediately after the start of use (initial) may be detected, and the variation in the current value may be corrected using this value.

[0050] The fixing device of the present embodiment having the above-described configuration can easily, efficiently, and effectively detect the remaining amount of the cleaning web by a single detection means without using a special cleaning web, while preventing cost increase and malfunction.

Explanation of Reference Numerals

[0051] 30 Fixing member 31 Pressing member 40 Filler 40a Contact portion 40b Detected portion 40c Fulcrum 41 Cleaning web 42 Sensor 43 Drive motor 44 Web holding member 45 Pressing member 46 Take-up member 50 Side plate 121 Fixing device 122 Cleaning means

Prior Art Documents

Patent Documents

[0052]

Patent Document 1

Claims

1. A fixing device comprising a fixing member which is a rotating body heated by a heating means, and a pressing member which forms a fixing nip portion between the fixing member, and which conveys a recording medium carrying an unfixed toner image to the fixing nip portion to fix the toner image on the recording medium, comprising cleaning means for removing residual toner adhering to the surface of the fixing member, the cleaning means comprising a cleaning web for wiping the surface of the fixing member, a web holding member for holding the cleaning web so as to be feedable, a winding member for winding up the cleaning web, a pressing member for pressing the cleaning web against the fixing member, and a single detecting means for detecting the remaining amount of the cleaning web held by the web holding member, the detecting means having a filler that is displaced according to the remaining amount of the cleaning web and a sensor for detecting the filler, and detecting a web near end state in which the cleaning web is about to run out and a web end state in which the cleaning web has run out, respectively, wherein the sensor of the detecting means is off when the remaining amount of the cleaning web held by the web holding member is sufficient, on in the web near end state, and off again in the web end state. A fixing device characterized by this.

2. A fixing device comprising a fixing member which is a rotating body heated by a heating means, and a pressing member which forms a fixing nip portion between the fixing member, and which conveys a recording medium carrying an unfixed toner image to the fixing nip portion to fix the toner image on the recording medium, comprising cleaning means for removing residual toner adhering to the surface of the fixing member, the cleaning means comprising a cleaning web for wiping the surface of the fixing member, a web holding member for holding the cleaning web so as to be feedable, a winding member for winding up the cleaning web, a pressing member for pressing the cleaning web against the fixing member, and a single detecting means for detecting the remaining amount of the cleaning web held by the web holding member, the detecting means having a filler that is displaced according to the remaining amount of the cleaning web and a sensor for detecting the filler, and detecting a web near end state in which the cleaning web is about to run out and a web end state in which the cleaning web has run out, respectively, The fuser is characterized in that it is not detected by the sensor when there is sufficient remaining amount of the cleaning web, is displaced to a position where it is detected by the sensor in the web near-end state, and is displaced to a position where it is not detected by the sensor in the web end state. **Claim 3**: A fixing device comprising a fixing member which is a rotating body heated by heating means, and a pressing member which forms a fixing nip portion between the fixing member, for conveying a recording medium carrying an unfixed toner image to the fixing nip portion and fixing the toner image on the recording medium, comprising cleaning means for removing residual toner adhering to the surface of the fixing member, wherein the cleaning means includes a cleaning web for wiping the surface of the fixing member, a web holding member for holding the cleaning web so as to be feedable, a winding member for winding up the cleaning web, a pressing member for pressing the cleaning web against the fixing member, and a single detecting means for detecting the remaining amount of the cleaning web held by the web holding member. The detecting means has a filler that is displaced according to the remaining amount of the cleaning web and a sensor for detecting the filler, and respectively detects a web near-end state where the cleaning web is about to run out and a web end state where the cleaning web has run out. The fixing device further includes a drive motor for the winding member and means for detecting a change in the current value accompanying a torque fluctuation of the drive motor, calculates the amount of the cleaning web wound around the winding member from the change in the current value, and compares it with the state of the remaining amount of the cleaning web detected by the detecting means. **Claim 4** The fuser according to claim 1, wherein the filler is not detected by the sensor when there is sufficient remaining amount of the cleaning web, is displaced to a position where it is detected by the sensor in the web near-end state, and is displaced to a position where it is not detected by the sensor in the web end state. **Claim 5** The fixing device according to any one of claims 1, 2, and 4, further comprising a drive motor for the winding member and means for detecting a change in the current value accompanying a torque fluctuation of the drive motor, calculates the amount of the cleaning web wound around the winding member from the change in the current value, and compares it with the state of the remaining amount of the cleaning web detected by the detecting means.

6. The fixing device according to any one of claims 1 to 5, wherein the sensor is a photosensor.

7. The fixing device according to claim 3 or 5, wherein a current value associated with torque fluctuation of the drive motor is corrected by at least any one of a temperature condition, a value of a power supply voltage, and a horizontal state of the device.

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

Images