JP2004325815A - Fixing device, image forming device, and holder for fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably detect a recording medium peeled off from a rotating body. <P>SOLUTION: A paper sheet 150 to which a developer is fixed is peeled off from a heating roll 74 by a peeling pawl 106 and the tip of the paper sheet 150 is abutted to the abutting part 124 of an actuator 120 provided near the peeling pawl 106. When the paper sheet 150 abuts on the abutting part 124, the actuator 120 is swung with a spindle 128 as an axis by a pressure from the paper sheet 150. Then, in the actuator 120 which receives the pressure, a light shielding part 126 is lowered downwards and the optical path of optical signals interrupted between a light emitting part 134 and a light receiving part 136 is opened. When the optical path is opened, the light receiving part 136 detects the paper sheet 150 by receiving the optical signals outputted from the light emitting part 134. When the paper sheet 150 stably passes through a detector 108, the actuator 120 interrupts the optical signals outputted from the light emitting part 134 again by the light shielding part 126. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fixing device, an image forming device, and a fixing device holder.
[0002]
[Prior art]
2. Description of the Related Art As a fixing device of an image forming apparatus, a heat and pressure fixing type having a pair of rotating members pressed against each other is well known. In this type of fixing device, the paper may be wrapped around the rotating body, causing a paper jam.
Patent Document 1 discloses that an actuator and a sensor are provided on a maintenance opening / closing cover of an image forming apparatus in order to detect whether a sheet has passed without being wound around a rotating body.
Japanese Patent Application Laid-Open No. H11-163873 discloses that a reflection type sensor is used to determine whether or not a sheet is wound around a rotating body based on a change in the amount of light reflected from the rotating body.
[0003]
[Patent Document 1] Japanese Patent Application Laid-Open No. 10-171275 [Patent Document 2] Japanese Patent Application Laid-Open No. 7-31511
[Problems to be solved by the invention]
However, as described in Patent Document 1, when an actuator and a sensor for detecting the passage of the paper are provided on the maintenance opening / closing cover, the positioning accuracy of the actuator with respect to the rotating body cannot be improved, and the timing for detecting the passage of the paper is inadequate. May be stable.
Further, as described in Patent Document 2, when detecting whether or not a sheet of paper is wound around a rotating body by a reflection type sensor, the detection accuracy is unstable due to the accuracy of the reflection type sensor and a change in ambient temperature. It may be.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing device capable of stably detecting a recording medium peeled from a rotating body and an image forming apparatus having the same.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is characterized in that a pair of rotating bodies facing each other, a main body rotatably supporting the rotating bodies, and a recording medium passing between the rotating bodies from the rotating bodies. The fixing device includes a peeling claw to be peeled off, a detecting means for detecting the recording medium, at least one component constituting the detecting means, and a holder for holding the peeling claw with respect to the main body.
[0007] Further, it is preferable that the detecting means includes an actuator that comes into contact with the recording medium and a detecting unit that detects a displacement of the actuator, and the holder preferably holds the actuator and the peeling claw.
Preferably, the holder is provided so as to be detachable from the main body.
According to a second feature of the present invention, a pair of rotating bodies facing each other, a peeling claw for peeling a recording medium passing between the rotating bodies from the rotating bodies, and a recording medium are detected. A fixing device having a detecting unit, wherein the peeling claw and the detecting unit are arranged close to each other.
A third feature of the present invention is that a pair of rotating bodies facing each other, a transport path for transporting a recording medium between the rotating bodies, and a downstream side of the transport path between the rotating bodies. A separating claw that separates the recording medium from the rotating body, a detecting unit that is disposed near the separating claw and detects the recording medium, at least one component that configures the detecting unit, and a holder that holds the separating claw And an image forming apparatus having:
A fourth feature of the present invention is that a pair of rotating bodies opposed to each other, a transport path for transporting a recording medium between the rotating bodies, and a downstream side of the transport path between the rotating bodies. An image forming apparatus includes a peeling claw that peels a recording medium from the rotating body, and a detecting unit that detects the recording medium, wherein the peeling claw and the detecting unit are arranged in close proximity.
According to a fifth feature of the present invention, a separating claw for separating a recording medium passing between a pair of opposed rotating bodies from the rotating body and a detecting means for detecting the recording medium are provided. The fixing device holder holds the at least one component integrally.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 has an image forming apparatus main body 12, an image forming unit 14 is mounted in the image forming apparatus main body 12, and a discharge unit 16 described later is provided above the image forming apparatus main body 12. At the same time, for example, two-stage paper feed units 18 are arranged below the image forming apparatus main body 12. Further, a plurality of paper feed units can be optionally arranged below the image forming apparatus main body 12.
Each paper supply unit 18 has a paper supply unit main body 20 and a paper supply cassette 22 for storing paper. A pickup roll 24 is disposed in the upper portion near the back end of the sheet cassette 22, and a retard roll 26 and a feed roll 28 are disposed behind the pickup roll 24.
The main transport path 32 is a paper path from the feed roll 28 to the discharge port 34. The main transport path 32 is located near the back side (left side in FIG. 1) of the image forming apparatus main body 12, and It has a portion that is formed substantially vertically from the paper feed unit 18 at the lower end to a fixing device 36 described later. A transfer device 42 and an image carrier 44, which will be described later, are arranged upstream of the fixing device 36 in the main transport path 32, and a registration roll 38 is arranged upstream of the transfer device 42 and the image carrier 44. Further, a discharge roll 40 is disposed near the discharge port 34 of the main transport path 32.
Therefore, the paper fed from the paper feed cassette 22 of the paper feed unit 18 by the pickup roll 24 is separated by the cooperation of the retard roll 26 and the feed roll 28, and only the uppermost paper is guided to the main transport path 32. Then, the developer image is temporarily stopped by the registration roll 38, and the developer image is transferred at a time between the transfer device 42 and the image carrier 44, which will be described later, and the transferred developer image is fixed by the fixing device 36. Then, the sheet is discharged from the discharge port 34 to the discharge section 16 by the discharge roll 40.
However, in the case of double-sided printing, it is returned to the reversing path. That is, the main transport path 32 is branched into two parts before the discharge roll 40, a switching device 46 is provided in the divided part, and a reversing path 48 that returns from the divided part to the registration roll 38 is formed. . The reversing path 48 is provided with transport rolls 50a to 50c. In the case of double-sided printing, the switching device 46 is switched to the side where the reversing path 48 is opened, and the time when the trailing end of the sheet is applied to the discharge roll 40 is reached. Then, the discharge roll 40 is reversed, and the sheet is guided to the reversing path 48, and is discharged from the discharge port 34 to the discharge unit 16 through the registration roll 38, the transfer device 42, the image carrier 44, and the fixing device 36. .
The image forming means 14 is of, for example, an electrophotographic type, and includes an image carrier 44 made of a photosensitive member, a charging device 56 made of, for example, a charging roll for uniformly charging the image carrier 44, and a charging device 56. An optical writing device 58 for writing a latent image by light on the image carrier 44 charged by the optical writing device 58; a developing device 60 for visualizing the latent image of the image carrier 44 formed by the optical writing device 58 with a developer; The transfer device 42 formed of, for example, a transfer roll for transferring the developer image by the developing device 60 to the sheet, the cleaning device 62 formed of, for example, a blade for cleaning the developer remaining on the image carrier 44, and the image transferred by the transfer device 42 And a fixing device 36 for fixing the developer image on the sheet to the sheet. The optical writing device 58 is composed of, for example, a scanning type laser exposure device, is disposed in parallel with the above-described paper feeding unit 18 and near the front of the image forming apparatus main body 12, and exposes the image carrier 44 across the inside of the developing device 60. . Further, the optical writing device 58 exposes the image carrier 44 under the control of the control unit 144 described later. Then, the exposure position of the image carrier 44 becomes the latent image writing position P. In this embodiment, a scanning laser exposure device is used as the optical writing device 58. However, as another embodiment, an LED, a surface emitting laser, or the like can be used.
The process cartridge 64 integrates the image carrier 44, the charging device 56, the developing device 60 and the cleaning device 62, and these can be exchanged as one. The process cartridge 64 can be removed from the image forming apparatus main body 12 by opening the discharge unit 16.
FIGS. 2 to 5 show the configuration of the fixing device 36. FIG. The fixing device 36 is unitized, for example, and has a unit main body 66. The unit main body 66 is configured by combining a first housing 68 and a second housing 70. That is, the first housing 68 and the second housing 70 are connected via the main body fulcrum 72, and the heating roll 74 is rotatably supported by the first housing 68. A pressure roll 76 is rotatably supported by the housing 70. The pressing roll 76 is pressed against the heating roll 74 by two pressing elastic members 78 and 78 made of a coil spring or the like, so that a nip portion 80 is formed. One end of each of the pressing elastic bodies 78 is supported by the rotating cams 82 and the other end thereof is hooked to the first housing 68. The rotating cam 82 is rotatably supported by one end of a bracket 84, and expands and contracts the pressing elastic body 78 by rotating. The other end of the bracket 84 is supported on a fulcrum 86.
The above-described main transport path 32 is formed vertically with the nip 80 interposed therebetween, and the paper is transported upward from below. An inlet chute (transport guide) 88 made of, for example, a plate-like metal is disposed upstream of the nip 80, and outlet chutes 90 a and 90 b are disposed downstream of the nip 80. The outlet-side chutes 90a and 90b are provided on the first housing 68 side and the second housing 70 side, and the outlet-side chutes 90a on the second housing 70 side rotate upward. The paper is made to pass through.
The pressure roll 76 has a rotating shaft 92 made of, for example, stainless steel or iron, and rotates about the rotating shaft 92, and has a thickness of, for example, 6 to 8 mm, such as a silicon sponge (Asker C hardness: 40 degrees). And a cover layer 96 covering the surface of the heat-resistant elastic layer 94. The coating layer 96 is made of, for example, perfluoroalkoxy (PFA) and has a thickness of, for example, 20 to 100 μm.
The heating roll 74 has a cylindrical core 98 and a release layer 100 covering the surface of the core 98. The core 98 has a thickness of, for example, 0.5 to 1.5 mm. The material forming the core 98 is, for example, iron or aluminum. The release layer 100 is formed of, for example, PFA, and has a thickness of, for example, 30 to 100 μm. The material forming the release layer 100 may be ethylene tetrafluoride (PTFE). Then, a heater 102 formed of, for example, a lamp is arranged in the heating roll 74 and heats the heating roll 74.
Further, a thermostat 104 is provided in the first housing 68 in the vicinity of the heating roll 74 so as to face the heating roll 74. When the temperature of the heating roll 74 rises abnormally, the thermostat 104 detects the abnormal temperature and shuts off the power supply to the heater 102.
The first casing 68 is provided with, for example, five peeling claws 106 on the downstream side of the nip portion 80 of the main transport path 32. Each of the peeling claws 106 is spaced apart in the axial direction of the heating roll 74 (in the width direction of the paper), and is applied with a weak force that does not damage the surface of the heating roll 74 by, for example, a torsion coil spring (not shown). It is urged toward the heating roll 74 and comes into sliding contact with the release layer 100. The peeling claw 106 peels off the paper to be wound around the heating roll 74. The material forming the peeling claw 106 is, for example, thermoplastic polyimide (TPI) and polyphenylene sulfide (PPS).
Further, a detection device 108 for detecting the sheet peeled off by the peeling claw 106 is provided in the vicinity of the peeling claw 106 slidably in contact with the heating roll 74 substantially at the center of the heating roll 74, for example.
Bearings 110 and 110 having, for example, stainless steel balls are mounted near both ends of the heating roll 74, and the heating roll 74 is fixed to the first housing 68 via the bearings 110 and 110. I have. Further, a gear 112 is provided at one end of the heating roll 74. The heating roll 74 is configured to rotate when the gear 112 receives a driving force from another gear (not shown).
Next, the detection device 108 and its peripheral configuration will be described.
6 to 8, the detection device 108 and members around the detection device 108 are shown. The first housing 68 includes support portions 114a and 114b, and the support portion 114a is engaged with a holder 116 that holds an exfoliation claw 106 and an actuator 120 described later. The peeling claw 106 is swingably supported by the claw shaft 118, is held by the holder 116 via the claw shaft 118, and comes into sliding contact with the release layer 100. The detection device 108 includes an actuator 120 that is displaced by contacting a sheet, and a detection unit 122 that detects the displacement of the actuator 120, such as a photo interrupter, and is provided near the peeling claw 106 as described above. Have been.
The actuator 120 has a contact portion 124 for contacting the sheet and a light shielding portion 126 for blocking an optical signal, which will be described later. The actuator 120 is swingably supported by a support shaft 128, is held by the holder 116 via the support shaft 128, and is moved toward the main transport path 32 (standby position) by an elastic body 130 such as a torsion coil spring. It is biased toward. As described above, the holder 116 engages the holder elastic claws 132, 132 with the support portion 114 a while holding the peeling claw 106 and the actuator 120 close to each other, so that the peeling claw 106 and the actuator 120 with respect to the heating roll 74 are held. Perform positioning.
The detecting section 122 includes a light emitting section 134 for outputting an optical signal, a light receiving section 136 for receiving the optical signal output from the light emitting section 134, and a side elastic claw 138 which engages from the inside with the side of the supporting section 114b. And an upper elastic claw 140 that engages from above and above the support 114b, and a lower elastic claw 142 that engages from below and below the support 114b. The detection unit 122 is positioned by engaging the side elastic claws 138, the upper elastic claws 140, and the lower elastic claws 142 with the support 114b, and moves from the light emitting position L1 of the light emitting unit 134 to the light receiving position L2 of the light receiving unit 136. The light path of the optical signal output toward the light shielding section 126 of the actuator 120 is cut off.
Then, the light receiving section 136 outputs to the control section 144 a signal indicating whether or not an optical signal from the light emitting section 134 has been received. The control unit 144 includes a CPU 146 and a memory 148, and determines whether or not the sheet is stably passing through the main transport path 32 based on a signal input from the light receiving unit 136. The memory 148 stores, for example, a standard time (predetermined time) from when the registration roll 38 starts transporting the paper to when the light receiving unit 136 receives (receives) the interrupted optical signal. , A predetermined time stored in the memory 148. Further, the control unit 144 controls the registration roll 38, and stores the time from when the registration roll 38 starts conveying the sheet to when the light receiving unit 136 receives (receives) the blocked optical signal, and a memory. 148 is configured to be able to compare with a predetermined time stored.
For example, when the sheet is wound around the heating roll 74, the actuator 120 does not swing and the light receiving section 136 does not receive light within a predetermined time, so that the control section 144 determines that the sheet is not stably conveyed. Judge. If the control unit 144 determines that the sheet is not being conveyed stably, it stops, for example, the image forming operation of the image forming apparatus 10 (including the stop of energization to the heater 102), or controls the conveyance of the sheet. The fact that there is a defect is displayed on a display unit (not shown).
Next, the operation of the above embodiment will be described.
When the image forming signal is sent, the image carrier 44 is uniformly charged by the charging device 56, and the charged image carrier 44 is irradiated with light emitted from the optical writing device 58 based on the image signal. , A latent image is formed at the latent image writing position P. Light from the optical writing device 58 passes through the process cartridge 64. The latent image on the image carrier 44 formed by the optical writing device 58 is visualized by the developer of the developing device 60.
On the other hand, one of the paper feeding units 18 is selected by a size signal or the like, and the paper stored in one of the paper feeding cassettes 22 is sent out by a pickup roll 24 and is fed by a retard roll 26 and a feed roll 28. The paper is separated and guided to the main transport path 32, temporarily stopped by the registration roll 38, and guided between the transfer device 42 and the image carrier 44 at a certain timing. When the sheet is guided between the transfer device 42 and the image carrier 44, the developer on the image carrier 44 is transferred to the sheet by the transfer device 42. The sheet on which the developer has been transferred is guided to the fixing device 36, and the developer is fixed by the heat pressure of the heating roll 74 and the pressure roll 76.
FIG. 9 is a diagram showing the operation of the peeling claw 106 and the detecting device 108. The paper 150 on which the developer is fixed is peeled off from the heating roll 74 by the peeling claw 106, and the leading end of the paper 150 comes into contact with the contact portion 124 of the actuator 120 provided near the peeling claw 106. When the paper 150 abuts, the actuator 120 swings (clockwise in FIG. 9) around the support shaft 128 by the pressure from the paper 150. Then, in the actuator 120 that has received the pressure, the light shielding unit 126 is lowered, and the optical path of the optical signal blocked between the light emitting unit 134 and the light receiving unit 136 is opened. When the optical path is opened, the light receiving unit 136 receives the optical signal output from the light emitting unit 134 and outputs a signal indicating that the optical signal has been received to the control unit 144.
The control unit 144 measures the time from when the registration roll 38 starts transporting the paper to when the light receiving unit 136 receives (receives) the interrupted optical signal, for example. It is determined whether or not the paper 150 is stably conveyed based on whether or not the time is within the time. When the control unit 144 determines that the sheet 150 is not being stably conveyed, the control unit 144 stops the image forming operation of the image forming apparatus 10 or notifies the display unit (not shown) that there is a problem in the sheet conveyance. Display. When the paper 150 passes through the detection device 108, the actuator 120 is urged toward the main transport path 32 by the elastic body 130, and again shuts off the optical signal output from the light emitting unit 134 by the light shielding unit 126.
When the sheet passes through the fixing device 36, the sheet is discharged from the discharge port 34 to the discharge section 16 by the discharge roll 40. However, in the case of double-sided printing, the sheet is returned to the reversing path, and is again discharged from the discharge port 34 to the discharge section 16 through the registration roll 38, the transfer device 42, the image carrier 44, and the fixing device 36.
Next, control of the control unit 144 based on a signal input from the light receiving unit 136 will be described.
FIG. 10 is a flowchart (S10) illustrating control of the control unit 144 based on a signal input from the light receiving unit 136. As shown in FIG. 10, in step 100 (S100), the control unit 144 controls the registration roll 38 and starts transporting the paper 150 toward the image forming unit 14.
In step 102 (S102), the control unit 144 starts measuring time from when the registration roll 38 starts conveying the paper.
In step 104 (S 104), the control unit 144 compares the time (elapsed time) from the time when the registration roll 38 starts transporting the sheet with the predetermined time stored in the memory 148. Then, when the elapsed time is within the predetermined time, the control unit 144 proceeds to the process of S106, and when the elapsed time exceeds the predetermined time, the control unit 144 proceeds to the process of S110.
In step 106 (S106), control unit 144 receives from light receiving unit 136 a signal indicating whether light receiving unit 136 has received an optical signal from light emitting unit 134. Then, when receiving a signal indicating that the light receiving unit 136 has received the optical signal, the control unit 144 proceeds to the process of S108, and otherwise, proceeds to the process of S104.
In step 108 (S108), the control unit 144 ends the measurement of the elapsed time.
In step 110 (S110), control unit 144 stops the image forming operation in image forming apparatus 10.
In step 112 (S112), the control section 144 causes a display section (not shown) to display that there is a problem in sheet conveyance.
As described above, since the peeling claw 106 and the actuator 120 are held by the holder 116, it is possible to reduce the variation in the position of the actuator 120 with respect to the peeling claw 106, and the detecting device 108 detects the sheet. Can be stabilized.
Immediately after the sheet is peeled off from the heating roll 74, the posture of the leading end of the sheet is determined by the outer shape of the peeling claw 106. By disposing the actuator 120 near the peeling claw 106, the position where the leading end of the sheet contacts the actuator 120 and the attitude of the sheet can be stabilized, and the timing at which the detection device 108 detects the sheet can be stabilized. be able to.
Further, the position at which the peeling claw 106 slides on the heating roll 74 and the position at which the sheet comes into contact with the abutting portion 124 are brought closer to each other to reduce variations in these positions. Can be detected at an early stage, and the accuracy of paper transport control can be improved.
The detecting device 108 is arranged close to the peeling claw 106, and by detecting the displacement of the actuator 120 by the paper by the detecting unit 122, it is possible to improve the detecting accuracy and to be inexpensively constructed. it can.
Further, since the peeling claw 106 and the actuator 120 are held by the holder 116, assembly and maintenance of the fixing device 36 can be facilitated.
[0046]
As described above, according to the present invention, since at least one component constituting the detecting device and the holder for holding the peeling claw are provided, the recording medium peeled from the rotating body can be stabilized. Can be detected.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view showing a fixing device according to the embodiment of the present invention.
FIG. 3 is a diagram illustrating a side surface near a pressing elastic body of the fixing device illustrated in FIG. 2;
FIG. 4 is a schematic diagram illustrating a cross section of the fixing device illustrated in FIG. 2;
FIG. 5 is a perspective view showing the vicinity of a heating roll of the fixing device shown in FIG. 2;
FIG. 6 is a diagram illustrating the periphery of a peeling claw and a detection device.
FIG. 7 is a perspective view showing a combination of a peeling claw, a detecting device, and a holding member.
FIG. 8 is a diagram illustrating an upper surface of the combination illustrated in FIG. 7 and illustrating connection with a control unit.
FIG. 9 is a diagram illustrating the operation of the peeling claw and the detection device.
FIG. 10 is a flowchart illustrating control of a control unit based on a signal input from a light receiving unit.
[Explanation of symbols]
Reference Signs List 10 Image forming apparatus 12 Image forming apparatus main body 32 Main transport path 36 Fixing device 66 Unit main body 68 First housing 70 Second housing 74 Heating roll 102 Heater 106 Peeling claw 108 Detecting devices 114a, 114b Support section 116 Holder 118 Claw shaft 120 Actuator 122 Detecting part 124 Contact part 126 Light shielding part 128 Support shaft 130 Elastic body 132 Holder elastic claw 134 Light emitting part 136 Light receiving part 138 Side elastic claw 140 Upper elastic claw 142 Lower elastic claw 144 Control part 146 CPU
148 Memory 150 Paper

Claims (7)

A pair of rotating bodies opposed to each other, a main body rotatably supporting the rotating bodies, a separating claw for separating a recording medium passing between the rotating bodies from the rotating bodies, a detecting unit for detecting the recording medium, A fixing device comprising: at least one component constituting a detecting unit; and a holder for holding the peeling claw with respect to the main body. 2. The fixing device according to claim 1, wherein the detection unit includes an actuator that contacts the recording medium and a detection unit that detects a displacement of the actuator, and the holder holds the actuator and the peeling claw. apparatus. The fixing device according to claim 1, wherein the holder is detachably provided to the main body. It has a pair of rotating bodies opposed to each other, a peeling claw for peeling a recording medium passing between the rotating bodies from the rotating body, and a detecting means for detecting the recording medium, and the peeling claw and the detecting means are arranged close to each other. A fixing device, comprising: A pair of rotating bodies opposed to each other, a conveying path for conveying the recording medium between the rotating bodies, a separating claw for separating the recording medium from the rotating body on the downstream side of the conveying path between the rotating bodies, An image forming apparatus, comprising: a detection unit that is disposed in the vicinity and detects a recording medium; at least one component constituting the detection unit; and a holder that holds the peeling claw. A pair of rotating bodies opposed to each other, a conveying path for conveying the recording medium between the rotating bodies, a separation claw for separating the recording medium from the rotating bodies on a downstream side of the conveying path between the rotating bodies, and detecting the recording medium; An image forming apparatus, comprising: a detecting unit for detecting the peeling claw and the detecting unit. A fixing device, wherein a separation claw for separating a recording medium passing between a pair of opposed rotating bodies from the rotating body and at least one component constituting a detection unit for detecting the recording medium are integrally held. Device holder.

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