JP5156910B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device and an image forming apparatus, and in particular, a heating rotator having an elastic layer and a heat source, a pressure rotator disposed to face the heating rotator, the heating rotator, and the pressurization. A structure for holding the rotating body in pressure contact, a sensor member disposed in contact with the heating rotating body or in proximity to the heating rotating body, and biasing the sensor member to the fixing rotating body And a heating member, a pressurizing rotor, the structure, the sensor member, and an exterior member that encloses the biasing unit, and the recording medium includes the heating unit and the pressing unit. And a fixing device that fixes a toner image on the recording medium by passing through a nip portion formed by.

  In an electrophotographic image forming process in an image forming apparatus such as an electrophotographic printer, a FAX, or a copier, generally, a recording medium such as a recording sheet on which an unfixed toner image is formed is inserted into the image fixing apparatus and heated and pressurized. Thus, the toner image is fixed. Such an image fixing device is composed of a heating rotator in which a cylindrical cored bar is coated with at least an elastic layer and a heat source is disposed inside, and a pressure rotator that forms a nip portion in contact with the heating rotator. A heating and pressing type fixing device is generally used.

In such a fixing device, it is important that the surface temperature of the fixing rotator is maintained at an optimum value. For example, a temperature detection sensor represented by a contact type thermistor as disclosed in Patent Document 1 is used. The temperature of the heater in the fixing roller is generally controlled based on the measured surface temperature of the fixing roller. In addition, as a preventive measure when the heater control does not work for some reason and the heating rotator becomes an abnormally high temperature, there are many cases where a safety device for preventing excessive temperature rise is installed as a safety device. As a typical example, Patent Document 2 discloses a fixing device using a thermostat that detects the temperature of a fixing roller in a non-contact manner.
Utility Model Registration Publication No. 2505631 JP 2006-195324 A

  By the way, in the fixing device adopting the above-described heating and pressing method, generally, a rigid metal frame or the like so as to support a load for holding the fixing rotating body and the pressing rotating body in pressure contact with each other. The fixing rotator and the pressure rotator are held by this structure. In order to accurately detect the surface temperature of the fixing rotator, sensors such as thermistor and thermostat as described above are often arranged directly or through a member on a metal frame with high processing accuracy. As an enclosure that encloses a metal frame and sensors, a configuration in which the entire apparatus is covered with a resin housing is common.

  However, in the fixing device having such a configuration, when the harness connected to the sensors comes into contact with the edge portion of the metal frame, the covering of the harness is damaged, and the internal conductive wire is exposed, which is a safety problem. . In order to prevent this problem, it is necessary to take measures such as doubling the covering of the harness or guiding the harness with a resin member. This leads to an increase in product costs such as material costs and processing costs, and since the live parts are finally exposed by contacting the edge multiple times, it cannot be said to be a fundamental solution.

  For this reason, in many cases, a method of guiding the harness with a resin member is selected so that the harness is not easily damaged. However, if a resin guide that is separate from the frame is installed, a separate die is required, which increases the material cost. Increases the cost of the product. There is also a method to give the housing itself a guide shape that guides the harness. However, since the sensor body is held by the housing while being held by the frame, after the sensors are assembled to the frame, The harness must be applied after housing the frame in the housing. At that time, a process of assembling the harness to the harness guide inevitably occurs in a narrow space such as a gap between the frame and the housing.

  Therefore, the present invention provides a fixing device including at least a sensor member disposed in the vicinity of the heating rotator, can attach the sensor member with high accuracy, and can hold the sensor harness without damaging it, and It is an object of the present invention to provide a fixing device having good assembly workability.

The invention of claim 1
A heating rotator provided with an elastic layer and a heat source;
A pressure rotator disposed opposite the heating rotator;
A structure that holds the heating rotator and the pressure rotator in pressure contact with each other;
A sensor member disposed in contact with or adjacent to the heating rotator; and
Biasing means for biasing the sensor member to the heating rotator;
A nip formed by the heating rotator and the pressure rotator, the heating rotator , the pressure rotator, the structure, the sensor member, and an exterior member containing the biasing means. In a fixing device for fixing a toner image on the recording medium by passing through a section,
The sensor member is held by a holding means provided separately from the structure, and either of the holding means or the sensor member is applied to the structure by being biased by the biasing means . A fixing device in which a positional relationship of the sensor member with respect to the heating rotator is determined by contact,
A fixing device in which a part of the exterior member also serves as the holding unit or the holding unit is directly attached to the exterior member, and a part of the exterior member also serves as the biasing member. .

According to a second aspect of the present invention, in the fixing device according to the first aspect, the sensor member is a temperature detection sensor used in a contact method or a non-contact method with respect to a surface of a detection target.

According to a third aspect of the present invention, in the fixing device according to the second aspect, the temperature detection sensor is any one of a thermistor , a thermocouple , a thermostat, and a thermal fuse .

A fourth aspect of the present invention, in the fixing device according to claim 1 or 2, harness connected before xenon capacitors member is characterized Rukoto held by the harness holding portion to which the outer member has.

The invention of claim 5 is the fixing device according to claim 4, a portion of the outer member and said Rukoto serves as the harness holding portion.

According to a sixth aspect of the invention, in the fixing device according to claim 4 or 5, the harness holding member to which the outer member has found the external instrumentation member and said Rukoto configured separately.

According to a seventh aspect of the present invention, in the fixing device according to any one of the first to sixth aspects, the structure and the holding unit or the sensor member position the sensor member by a fitting shape that fits to each other. the configuration der Rukoto and features.

According to an eighth aspect of the present invention, in the fixing device according to the seventh aspect , a positioning convex member is disposed in the structure, and a positioning hole provided in the holding means is provided with respect to the convex member. There characterized Rukoto is positioned by fitting.

According to a ninth aspect of the present invention, in the fixing device according to the seventh aspect, a positioning convex member is disposed on the holding means, and the positioning provided on the structure relative to the convex member. It is characterized by being positioned by fitting the holes .

The invention of claim 10 is the fixing device according to any one of claims 1 to 9, characterized in Rukoto has said position confirming viewing window of the sensor member is provided in the outer member.

The invention of claim 11 is the fixing device according to any one of claims 1 to 10, wherein the heating rotator is characterized Oh Rukoto in heat fixing roller having a heat source and elastic layer therein.

According to a twelfth aspect of the present invention, in the fixing device according to any one of the first to eleventh aspects, the heating rotator is a single member that stretches the elastic layer, the heat source, the endless heating member, and the endless heating member. characterized Rukoto which having a plurality of rotatable rollers.

The invention of claim 13 is an image forming apparatus according to claim Rukoto comprises a wearing device according to any one of 請 Motomeko 1 12.

  According to the fixing device and the image forming apparatus according to the present invention, the sensor member is held by the holding unit provided separately from the structure, and receives the urging force from the urging member. Since any one of the sensor members comes into contact with the structure and the positional relationship of the sensor member with respect to the heating rotator is determined, the sensor is attached with high accuracy, and the sensor harness is damaged. It can hold | maintain without giving and can also make assembly | attachment workability | operativity favorable.

  Embodiments as the best mode for carrying out the present invention will be described below with reference to the drawings.

  Hereinafter, an embodiment as the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a sectional view conceptually showing an image forming apparatus according to an embodiment. The image forming apparatus according to this example includes a reading unit 11 that reads a document, an image forming unit 12 that forms an image, an automatic document feeder (ADF) 13, a document discharge tray 14 that stacks documents sent from the ADF 13, A sheet feeding unit 19 including cassettes 15 to 18 and a sheet discharge unit (discharge tray 20) for stacking recording sheets are configured.

  In this image forming apparatus, when the document D is set on the document table 21 of the ADF 13 and an operation on an operation unit (not shown), for example, a print key is pressed, the uppermost document D is rotated by the pickup roller 22. Is sent in the direction of the arrow B1 and is placed on the contact glass 24 fixed to the image reading unit 11 by the rotation of the document conveying belt 23. The image of the placed document D is read by a reading device 25 located between the image forming unit 12 and the contact glass 24. The reading device 25 includes a light source 26 that illuminates the document D on the contact glass 24, an optical system 27 that forms an image of the document, a photoelectric conversion element 28 that includes a CCD that forms an image of the document, and the like. After the image reading is completed, the document D is transported in the direction of arrow B2 by the rotation of the document transport belt 23 and is discharged onto the document discharge tray 14. In this way, the originals D are fed one by one onto the contact glass 24 and the original image is read by the image reading unit 11.

  On the other hand, inside the image forming unit 12, a photoconductor 30 as an image carrier is disposed. The photosensitive member 30 is rotated in the clockwise direction in the drawing, and the surface thereof is charged to a predetermined potential by the charging device 31. Further, the writing unit 32 is irradiated with laser light L that is light-modulated in accordance with image information read by the reading device 25, and the surface of the charged photoconductor 30 is exposed with the laser light L, whereby the photoconductor 30 is exposed. An electrostatic latent image is formed on the surface. When the electrostatic latent image passes through the developing device 33, the electrostatic latent image is transferred to the recording medium P fed between the photoreceptor 30 and the transfer device 34 by the opposing transfer device 34. The surface of the photoreceptor 30 after the toner image transfer is cleaned by a cleaning device 35.

  A plurality of paper feed cassettes 15 to 18 arranged in the lower part of the image forming unit 12 contain recording media P such as paper, and the recording media P is fed from any of the paper feed cassettes 15 to 18 in the direction of arrow B3. The toner image formed on the surface of the photoreceptor 30 as described above is transferred onto the surface of the recording medium P. Next, the recording medium P is passed through the fixing device 100 in the image forming unit 12 as indicated by an arrow B4, and the toner image transferred onto the surface of the recording medium P by the action of heat and pressure is fixed. The recording medium P that has passed through the fixing device 100 is conveyed by the discharge roller pair 37, and is discharged to the discharge tray 20 and stacked as indicated by an arrow B5.

  Next, the fixing device 100 of the image forming apparatus according to the present invention will be described. FIG. 2 is a perspective view showing a fixing device according to the embodiment, FIG. 3 shows a fixing device according to the embodiment, (a) is a cross-sectional view showing the attachment process of the thermistor, and (b) is the thermistor. It is sectional drawing which shows an attachment state. As shown in FIG. 2, the heat and pressure type fixing device 100 according to this embodiment is provided such that a pressure roller 121 and a heating roller 122 that is a heating rotating body face each other. The heating roller 122 has a heater 125 as a heat source therein and is rotationally driven by a drive motor (not shown). The pressure roller 121 is brought into pressure contact with the heating roller 122 by a pressure unit (not shown), and is driven to rotate as the heating roller 122 rotates.

  The pressure roller 121 is formed by providing an elastic layer such as silicon rubber on a core metal such as aluminum or iron, and its surface layer is a release layer composed of PFA or PTFE. A recording medium carrying an unfixed toner image is conveyed along a conveyance guide 128 to a nip formed by a pressure roller 121 and a heating roller 122, and subjected to heating and pressure processing. The roller pair is rotatably supported by a metal frame 131 that is a structure, and a resin housing 155 is disposed so as to cover the outer periphery of the frame 131.

  In the fixing device 100 according to this example, in order to manage the amount of heat given to the toner, as shown in FIG. 3B, a contact type thermistor 141 is brought into contact with the heating roller 122 to thereby surface the surface temperature of the heating roller 122. Is detected. Based on the temperature detected by the thermistor 141, the temperature of the roller surface is managed by controlling the blinking of the heater 125. The thermistor 141 is fixed to the holding member 161 by a fixing member such as a screw 181, and the holding member 161 is urged upward by the urging means 171. In this example, the biasing means 171 is a coil spring, for example, and is disposed on the housing 155.

  A stepped caulking pin 182 that is a convex member is disposed on the holding member 161. The frame 131 is formed with a positioning hole 132 into which the caulking pin 182 is fitted. The caulking pin 182 and the positioning hole 132 are fitted to each other, and the thermistor 141 is positioned with respect to the heating roller 122. When the fixing device 100 is assembled from the state shown in FIG. 3A, the thermistor 141 is urged by the urging means 171 and is positioned by the caulking pin 182 and the positioning hole 132, so that FIG. ) And fixed in contact with the heating roller 122.

  Next, holding of the harness 142 connected to the thermistor 141 will be described. FIG. 4 is a perspective view illustrating a holding state of the harness in the fixing device according to the exemplary embodiment. A harness 142 is connected to the rear end of the thermistor 141, and the other end of the harness 142 is connected to an electrical component such as a connector (not shown), and a detection signal from the thermistor 141 is transmitted to the image forming apparatus main body through the connector. doing. The wiring path of the harness 142 is determined by a harness holding portion 156 provided in the housing 155, and the harness 142 is caught in a movable portion such as a driving gear or a roller pair (not shown) or contacted with an edge such as a frame end. It is supposed not to.

  The harness holding portion 156 is formed by integrally forming a hook-shaped member having a base fixed to the housing 155 in the housing 155. For this reason, the thermistor 141 and the harness 142 extending from the thermistor are attached to the housing 155 by the harness holding portion 156, while being attached completely away from the frame 131, and the frame 131 and the housing 155 are contacted and separated. Therefore, the productivity at the time of assembling the fixing device 100 can be improved.

  In this example, a viewing window for confirming the position of the thermistor 141, which is a sensor member, can be opened in the housing 155, which is an exterior member. This improves the visibility of the thermistor in the assembled state, and can be It is possible to prevent the positional deviation of the sensor from the normal state that occurs.

  Therefore, according to the fixing device 100 according to the present example, the mounting accuracy of the thermistor 141 can be secured, the harness can be held while being damaged, and the assembly workability can be improved.

In this example, the positioning hole is formed in the holding member in the frame and the caulking pin is formed in the holding member. However, the positioning hole may be formed in the holding portion and the caulking pin may be formed in the frame. Moreover, it can replace with a crimping pin as a convex-shaped member, and can employ | adopt another member.

  Furthermore, in this example, the case where the harness holding portion is integrally formed with the housing is shown, but the harness holding portion can be attached to the housing as a separate member.

  Next, a second embodiment will be described. 5A and 5B show a fixing device according to the second embodiment. FIG. 5A is a cross-sectional view showing a thermostat mounting process, and FIG. 5B is a cross-sectional view showing a thermostat mounting state. In the fixing device 200 according to this example, a thermostat 245 is installed as a sensor member at an appropriate interval with respect to the surface layer of the heating roller 222. The thermostat 245 is arranged as a safety device for preventing excessive temperature rise, and is provided to cope with a case where the heater control does not work for some reason and the heating roller 222 becomes an abnormally high temperature.

  The thermostat 245 is fixed to the holding member 261 by a fixing member such as a screw 281. The holding member 261 is urged upward by the urging means 271 in the resin housing 255 method. In this example, the urging means 271 is integrally formed as a cantilever leaf spring on the housing 255 using the elasticity of the resin housing 255.

  The holding member 261 is provided with a positioning hole 262 for defining the position of the thermostat 245 with respect to the horizontal direction and the vertical direction in the drawing. In addition, an embossed portion 233 is formed on the frame 231 as a convex member that is fitted into the positioning hole 262. When the fixing device 200 is assembled from the state shown in FIG. 5A, the thermostat 245 is urged by the urging means 271 and positioned by the positioning hole 262, as shown in FIG. 5B. Thus, the heating roller 222 is fixed in a state of being separated by a predetermined distance d.

  Therefore, according to the fixing device 200 according to this example, the mounting accuracy of the thermostat 245 can be secured, the harness can be held while being prevented from being damaged, and the assembly workability can be improved.

  In each of the above examples, the thermistor and thermostat are used as the sensor member. However, a thermocouple, a temperature fuse, or the like can be used as the sensor member. In this example, the positioning hole is formed in the holding member and the embossed part is formed in the frame. However, the positioning hole may be formed in the frame and the embossed part may be formed in the holding member.

  In each of the above-described examples, the example in which the heating roller is used as the heating rotator has been described. However, as the heating rotator, the elastic layer, the heat source, the endless heating member, and the endless heating member are stretched as a single member or a plurality of members. With a rotatable roller can be used.

1 is a cross-sectional view conceptually showing an image forming apparatus according to an exemplary embodiment. 1 is a perspective view illustrating a fixing device according to an exemplary embodiment. 1A and 1B show a fixing device according to an embodiment, in which FIG. 1A is a cross-sectional view showing a thermistor attachment process, and FIG. 2B is a cross-sectional view showing a thermistor attachment state. FIG. 5 is a perspective view showing a holding state of a harness in the fixing device according to the exemplary embodiment. FIG. 2 shows a fixing device according to a second embodiment, where (a) is a cross-sectional view showing a thermostat attachment process, and (b) is a cross-sectional view showing a thermostat attachment state.

Explanation of symbols

11 Reading unit 12 Image forming unit 13 Automatic document feeder (ADF)
14 Document discharge trays 15 to 18 Paper feed cassette 19 Paper feed unit 20 Paper discharge tray 21 Document tray 22 Pickup roller 23 Document transport belt 24 Contact glass 25 Reading device 26 Light source 27 Optical system 28 Photoelectric conversion element 30 Photoconductor 31 Charging device 32 Writing unit 33 Developing device 34 Transfer device 35 Cleaning device 37 Discharge roller pair 100 Fixing device 121 Pressure roller 122 Heating roller (heating rotating body)
125 heater 128 transport guide 131 frame (structure)
132 Positioning hole 141 Thermistor (sensor member)
142 harness 155 housing 156 harness holding portion 161 holding member 171 biasing means 181 screw 182 caulking pin (convex shape member)
200 Fixing Device 222 Heating Roller (Heating Rotator)
231 frame (structure)
233 Embossed part (convex shaped member)
245 Thermostat (sensor member)
255 Housing 261 Holding member 262 Positioning hole 271 Biasing means 281 Screw

Claims (13)

A heating rotator provided with an elastic layer and a heat source;
A pressure rotator disposed opposite the heating rotator;
A structure that holds the heating rotator and the pressure rotator in pressure contact with each other;
A sensor member disposed in contact with or adjacent to the heating rotator; and
Biasing means for biasing the sensor member to the heating rotator;
A nip formed by the heating rotator and the pressure rotator, the heating rotator , the pressure rotator, the structure, the sensor member, and an exterior member containing the biasing means. In a fixing device for fixing a toner image on the recording medium by passing through a section,
The sensor member is held by a holding means provided separately from the structure, and either of the holding means or the sensor member is applied to the structure by being biased by the biasing means . A fixing device in which a positional relationship of the sensor member with respect to the heating rotator is determined by contact,
A fixing device , wherein a part of the exterior member also serves as the holding unit or the holding unit is directly attached to the exterior member, and a part of the exterior member also serves as the biasing unit.   The fixing device according to claim 1, wherein the sensor member is a temperature detection sensor used in a contact method or a non-contact method with respect to a surface to be detected. The fixing device according to claim 2, wherein the temperature detection sensor is one of a thermistor , a thermocouple , a thermostat, and a thermal fuse . Harness fixing device according to claim 1 or 2, characterized in Rukoto held by the harness holding portion to which the outer member has to be connected before the xenon capacitors member. The fixing device according to claim 4 in which a part of the outer member and said Rukoto serves as the harness holding portion. The harness holding member having the exterior member, the fixing device according to claim 4 or 5, characterized in Rukoto configured separately from the outer instrumentation member. The holding means or the sensor member and the structure, the fixing device according to any one of claims 1 to 6, characterized in configuration der Rukoto forming the positioning of the sensor member by the shape fit are fitted to each other . Is disposed is convex member for positioning the structure, the claims with respect to the convex-shaped member, a positioning hole provided in the holding means, characterized in Rukoto is positioned by fitting 8. The fixing device according to 7. A convex member for positioning is disposed on the holding means, and positioning is performed by fitting a positioning hole provided in the structure to the convex member. The fixing device according to 7 . The fixing device according to any one of claims 1 to 9, characterized that you have viewing window for localization of the sensor member is provided in the outer member. The heating rotating body, the fixing device according to any one of claims 1 to 10, characterized in Oh Rukoto in heat fixing roller having the elastic layer heat source therein. The heating rotator is, claim 1, wherein Rukoto which have a and one or more rotatable rollers for stretching the endless heating member and the elastic layer and the heat source and the endless heating member 11 of the The fixing device according to any one of the above. An image forming apparatus comprising Rukoto a fixing device according to any one of claims 1 to 12.