JP4739779B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that forms an image using an electrophotographic system such as a copying machine, a laser printer, a facsimile machine, and a multifunction machine of these, and a fixing device used in the image forming apparatus.

  In an electrophotographic image forming apparatus, a toner image is transferred onto a sheet or sheet-like film, a recording material on which the unfixed toner image is transferred is conveyed to a fixing device, and the unfixed toner image is heated and melted for recording. Established on the material.

  In the fixing device, a roller fixing system that fixes a non-fixed toner by passing a recording material between a pair of rollers that are arranged opposite to each other to form a nip portion, a fixing belt stretched around a plurality of rotating bodies, A belt for fixing unfixed toner by passing a recording material through a nip formed by the fixing belt and the pressure rotator, including a pressure rotator that is in pressure contact with one of the rotators across the fixing belt. There is a fixing method. As a fixing device of the belt fixing device, Patent Document 1 is cited.

  Such a fixing device includes a heating source that heats the fixing roller or the fixing belt to a predetermined temperature in order to melt the unfixed toner image at the nip portion. A rod-shaped heater is generally used as the heating source. One or more heaters are arranged in the roller around the fixing belt or in the fixing roller, and each has a power supply side terminal portion and a ground side terminal portion connected to the power supply side, and current is supplied from the power supply. As a result, heat is generated and the fixing belt and the fixing roller are heated from the inside. Patent Document 2 is an example of a fixing device having a plurality of heaters.

When using multiple heaters as a heat source, the number of heaters must be connected to the power supply terminal and grounding terminal of the heater to the power supply terminal and grounding terminal provided on the device body side by screwing, etc. Installation work was complicated.
Therefore, Patent Document 3 proposes a fixing device provided with a ground terminal integrated portion in which one end is connected to ground terminals of a plurality of heaters and the other end is connected to a main body ground terminal on the image forming apparatus side.

JP 2000-194225 A Japanese Patent Laid-Open No. 9-251253 JP 2002-296938

As in Japanese Patent Application Laid-Open No. H10-228707, when one end is connected to the ground side terminal of the plurality of heaters and the other end is connected to the main body ground terminal on the image forming apparatus side, the ground side terminal can be attached only once. However, since the power supply side terminals are separate, they may be twisted when housed inside the rotating body or when the power supply side terminals are connected to the power supply terminals on the device body side. The integrated part opens and closes, and the heater interval varies. Such a variation in the heater interval may cause uneven heating and eventually cause uneven fixing.
SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device and an image forming apparatus that have good workability at the time of terminal connection and removal, no unevenness in heating, and good fixability.

In order to achieve the above object, a recording material having a fixing rotator and a pressure rotator in pressure contact with the fixing rotator according to the present invention, to which an unfixed toner image is transferred, is pressed against the fixing rotator. In the fixing device that is fixed to the image forming apparatus main body by fixing the unfixed toner image on the recording material by passing through the nip formed by the rotating body, each of the power supply side terminal portion and A plurality of heaters having a ground side terminal portion, the ground side terminal portion being positioned on the mounting direction side of the image forming apparatus main body , and the power source side terminal portion being positioned on the mounting direction side in the detaching direction of the image forming apparatus main body ; A ground terminal integrated portion in which one end is integrated with a plurality of heater ground side terminals without using a fastening member, and the other end is connected to a main body ground terminal located on the mounting direction side of the image forming apparatus main body. , Heater power supply Holding member terminal portions, for retaining the heat source for heating the fixing rotator by being energized is connected to a power supply terminal provided in the removing direction side of the image forming apparatus main body, a plurality of heaters integrally One end of the ground terminal integrated part integrated with the ground side terminal part of the heater is arranged in the holding member.

The fixing device according to the present invention is characterized in that the fixing rotator is an endless fixing belt or a fixing roller stretched between a fixing roller and a heating roller.
An image forming apparatus according to the present invention includes any one of the fixing devices described above.

According to the present invention, one end is integrated without using a fastening member with the ground side terminals of a plurality of heaters positioned on the mounting direction side of the image forming apparatus main body, and the other end is provided on the mounting direction side of the image forming apparatus main body. A ground terminal integrated portion connected to the main body ground terminal, and each power source side terminal portion of the heater is connected to a power supply terminal provided on the detaching direction side of the image forming apparatus main body and energized. Since the heat source for heating the fixing rotator and the holding member for integrally holding the plurality of heaters are provided, the plurality of heaters are held by the holding member while ensuring workability at the time of connecting and removing the terminals. Can be maintained at a rare interval, and uneven heating with respect to the fixing rotator can be reduced to obtain good fixability.

According to the present invention, since one end of the ground terminal integrated portion integrated with the ground terminal portion of the heater is disposed in the holding member, the lead wire from the holding member to the heater terminal is connected. It is possible to reduce the damage and deformation of the conductive wire, and the durability is improved.

  Embodiments of the present invention will be described with reference to the drawings. In this embodiment, the image forming apparatus is a color printer (hereinafter referred to as “printer”) capable of forming a full-color image. The image forming apparatus is not limited to the printer shown in FIG. 1, and may be a copier, a facsimile, a complex machine of these, or the like.

  The basic configuration and operation of the printer will be described with reference to FIG. 1, and the configuration and operation unique to this embodiment will be described thereafter. In this printer, a sheet feeding unit 2 having a plurality of sheet feeding trays 12A and 12B in which a sheet 11 as a recording material is stored is disposed at the bottom of an image forming apparatus main body 1, and an image forming unit 3 is disposed above the sheet feeding unit 2. The arrangement is arranged. In the image forming unit 3, the image forming units 8Y, 8C, 8M, and 8K having the photosensitive drums 10Y, 10C, 10M, and 10K as image carriers and the flexible members wound around the rollers 4, 5, and 6 are provided. An intermediate transfer unit 7 having an intermediate transfer belt 7A serving as an intermediate transfer member, a writing unit 15 for performing optical writing on each photosensitive drum, and a fixing device 30 for fixing an unfixed toner image on the paper 11. It is arranged. A conveyance path 16 including a conveyance roller that conveys the paper 11 is formed between the paper feeding unit 2 and the fixing device 30.

  The image forming units 8Y, 8C, 8M, and 8K are provided with photosensitive drums 10Y, 10C, 10M, and 10K, and well-known charging devices, developing devices, and cleaning devices, respectively. On the other hand, it is detachable. The developing devices included in the image forming units 8Y, 8C, 8M, and 8K store yellow, cyan, magenta, and black toners, respectively. Each developing device is configured to supply replenishment toner from a toner bottle (not shown) when the toner is reduced.

  The intermediate transfer belt 7A is disposed so as to face each photosensitive drum, and is configured to rotate and move counterclockwise in FIG. 1 when any of a plurality of rollers is driven by a drive motor (not shown). Has been. Inside the transfer belt 7A facing each photoconductor drum, a transfer roller 14 serving as a primary transfer unit is disposed so that a transfer bias for primary transfer is applied. A belt cleaning device 17 that cleans the belt surface is disposed at a portion facing the roller 4. The intermediate transfer belt 7A, a plurality of rollers 4-6 around which the intermediate transfer belt 7A is wound, the transfer roller 14, and the belt cleaning device 17 are configured as an integrated unit and are detachable from the image forming apparatus main body 1. .

  A transfer roller 20 as a secondary transfer unit to which a secondary transfer bias is applied is brought into contact with the intermediate transfer belt 7 </ b> A at a portion facing the roller 6. The transfer roller 20 and a part of the transfer bell 7 </ b> A are disposed so as to face the conveyance path 23.

  The writing unit 15 irradiates the surface of each photosensitive drum with light-modulated laser light to form a latent image for each color on the surface of the photosensitive member. In this embodiment, the writing unit 15 is disposed below the image forming units 8Y, 8C, 8M, and 8K, and is configured to perform laser irradiation from the lower side of the apparatus toward the upper side of the apparatus.

  When the image forming operation is started, the photosensitive drums 10Y, 10C, 10M, and 10K of each image forming unit are rotationally driven clockwise by a driving unit (not shown), and the surface of each photosensitive drum is predetermined by each charging device. Uniformly charged to polarity. The surface of each charged photosensitive drum is irradiated with laser light from the writing unit 15 to form an electrostatic latent image on each surface. At this time, image information to be exposed on each photosensitive drum is single-color image information obtained by separating a desired full-color image into color information of yellow, cyan, magenta, and black. The electrostatic latent image formed in this way is visualized as a toner image by the toner of each developing device when passing between each photosensitive drum and the developing device.

  When the intermediate transfer belt 7A is moved in the counterclockwise direction by a driving means (not shown), yellow formed by an image forming unit 8Y having a developing device having yellow toner located on the most upstream side in the belt moving direction. The toner image is transferred by the transfer roller 14Y. To the transferred yellow toner image, the cyan toner image formed by the image forming units 8C, 8M and 8K, and further the magenta toner image and the black toner image are sequentially transferred and transferred by the transfer rollers 14C, 14M and 14K. The transfer belt 7A carries a full-color toner image on its surface.

  Residual toner adhering to the surface of each photosensitive drum after the toner image is transferred is removed from the surface of the photosensitive drum by each cleaning device, and then the surface is subjected to a static eliminating action by a static eliminator (not shown). The potential is initialized to prepare for the next image formation.

  On the other hand, the paper 11 is fed from the paper feeding unit 2 by the rotation of the paper feeding roller 18 </ b> A or the paper feeding roller 18 </ b> B and sent to the transport path 16. The fed paper 11 is fed by a registration roller pair 19 disposed on the conveyance path 16 on the paper feed side with respect to the secondary transfer roller 20, and the opposite portion between the roller 6 and the transfer roller 20. To be sent to. At this time, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the surface of the intermediate transfer belt is applied to the transfer roller 20, whereby the toner image on the surface of the intermediate transfer belt 7 A is collectively applied to the paper 11. Transcribed.

  The sheet 11 on which the toner image is transferred is conveyed to the fixing device 30, and heat and pressure are applied when passing through the fixing unit 30, and the unfixed toner image T is melted and fixed on the sheet 11. The sheet 11A on which the toner image is fixed is conveyed toward a discharge unit 21 positioned at the end of the conveyance path 23, and is discharged from the discharge unit 21 as a discharge unit provided on the upper portion of the image forming apparatus main body 1. It is discharged to the tray 22. After the toner image is transferred to the paper 11, the toner remaining on the intermediate transfer belt 7A is removed by the cleaning device 17.

Next, the fixing device 30 will be described.
The fixing device 30 includes a fixing rotator 32 and a pressure rotator 33 that is in pressure contact with the fixing rotator 32, and adds a sheet 11 as a recording material onto which the unfixed toner image T is transferred to the fixing rotator 32. The unfixed toner image T is fixed on the paper 11 by passing through the nip portion 31 formed by the pressure rotating body 33, and is configured to be detachable from the image forming apparatus main body 1.

  As shown in FIG. 2, the fixing rotator 32 constitutes a rotator disposed on the image surface side during single-sided printing of the paper 11, and the pressure rotator 33 is disposed on the non-image side during single-sided printing of the paper 11. Constitutes a rotating body.

  In this embodiment, the fixing rotator 32 includes a heat-resistant endless fixing belt 36 that is wound between a fixing roller 34 and a heating roller 35 serving as a plurality of rotators. The fixing roller 34 and the heating roller 35 have their shafts 37 and 38 rotatably supported by a casing 40 as a main body of the fixing device 30 so that the rotation center position is fixed, and the pitch between the shafts is small. It is assumed to be constant.

  The fixing roller 34 is disposed on the conveyance path 23 side, and the conveyance path 23 is desired to have a surface 36A of the fixing belt 36 wound around the outer peripheral surface thereof. The fixing roller 34 is made of an elastic body such as rubber. The heating roller 35 is a hollow metal roller, and a plurality (two in this embodiment) of heaters 41 and 42 constituting the heating source 400 are disposed therein. Examples of the heaters 41 and 42 include halogen heaters and infrared heaters, but other heaters may be used.

  Inside the fixing belt 36 located between the fixing roller 34 and the heating roller 35, a tension roller 45 as a belt stretching member pressed by a pressing means such as a spring (not shown) from the inside of the belt toward the outside. The fixing belt 34 wound around the fixing roller 34 and the heating roller 35 is stretched by applying an appropriate tension.

  The pressure rotator 33 is configured as a pressure roller in pressure contact with the fixing roller 34 with the fixing belt 36 interposed therebetween. The pressurizing rotator 33 is a hollow roller, and in this embodiment, a heater 49 as a heating unit is provided therein and also functions as a heating roller. The pressure rotator 33 is rotatably supported on the casing 40 by its shaft 48 and is configured to be displaced relative to the fixing roller 34. That is, when the pressure rotator 33 is thermally expanded as shown in FIG. 3A, the thickness of the sheet 11 fluctuates as shown in FIG. 1 and 3, the shaft 48 is supported so as to be movable in the left-right direction, and is pressed against the outer peripheral surface 34A of the fixing roller 34 via the fixing belt 36 by a biasing means such as a spring (not shown). Is configured to do.

  In the vicinity of the rotator 32, a non-contact temperature sensor 50 is disposed as a temperature detection unit that detects the temperature of the fixing belt 36 in a non-contact state. The non-contact temperature sensor 50 is disposed at a position for detecting the surface temperature of the fixing belt 36 wound around the heating roller 35. Although the thermistor is used for the non-contact temperature sensor 50, other sensors that can detect the temperature in a non-contact manner may be used.

  In the vicinity of the fixing belt 36 wound around the fixing roller 34, a separation member 43 that separates the paper 11 </ b> A on which the toner image T <b> 1 is fixed through the nip portion 31 from the surface 36 </ b> A of the fixing belt 36 is provided on the belt surface. It is arranged in a state of being separated from 36A. The separation member 43 is configured as a plate-like member extending in the axial direction of the fixing roller 34, but may be formed in a comb-teeth shape.

  In the vicinity of the pressure rotator 33, a cleaning member 44 that contacts the outer peripheral surface 33A and removes paper dust and toner adhering to the outer peripheral surface 33A is disposed. The cleaning member 44 of the present embodiment is configured by a roller member that extends in the positive axial direction of the pressure rotator 33. The cleaning member 44 is disposed upstream of the contact-type temperature sensor 51 and on the downstream side of the nip portion 31 with respect to the rotational direction of the pressure rotator 33.

  Paper guide members 45 and 46 are attached to the casing 40 and disposed on the pressure rotating body 33 side on the upstream side and the downstream side in the paper conveyance direction with respect to the nip portion 31. The paper guide member 45 is disposed in the vicinity of the introduction port 40 </ b> A formed in the casing 40, and guides the paper 11 on which the unfixed toner image T is transferred to the nip portion 31. The paper guide member 46 is attached to the casing 40 so as to expand toward the end with the separation member 43 and the conveyance path 23 sandwiched between the discharge port 40 </ b> B formed in the casing 40. The fixing device 30 is mounted on the image forming apparatus main body 1 such that the introduction port 40 </ b> A and the discharge port 40 </ b> B are positioned on the conveyance path 23. The casing 40 includes at least a fixing rotator 32, a pressure rotator 33, a separation member 43, and a cleaning member 44.

As shown in FIGS. 4 and 5, the heaters 41 and 42 are rod-shaped heaters extending in the rotation axis direction of the heating roller 35. The heaters 41 and 42 protrude from both ends of the heating roller 35, and power supply side terminal portions 41A and 42A and ground side terminal portions 41B and 42B are formed at the protruding ends, respectively. Ground-side terminal portion 41B, 42B, one end 401 B power supply side terminal portion 41A, are connected to 42A, as the other end 401 A is shown in FIG. 6, body ground terminals provided in the image forming apparatus main body 1 side It is connected to and integrated with a ground terminal integrated portion 401 that is coupled to 403 with a screw (not shown). The power supply side terminal portions 41A and 42A are coupled to power supply terminals 404 and 405 provided on the image forming apparatus main body 1 side by screws (not shown).

  Insulating portions 411 and 412 are provided at both ends of the heaters 41 and 42. The heaters 41 and 42 are held at regular intervals by the portions of the insulating portions 411 and 412 supported by heater support plates 406 and 407 serving as holding members, and are arranged at the center in the heating roller 35. . The heater support plates 406 and 407 are constituted by the outer plate of the casing 40. The heater support plates 406 and 407 may have a configuration in which a bracket is separately arranged in the casing 40.

  The non-contact temperature sensor 50, the heaters 41 and 42, and the heater 49 are connected to the control means 60 as shown in FIG. Based on the temperature information detected by the non-contact temperature sensor 50, the control means 60 energizes each heater so that the temperature of the fixing belt 36, preferably the temperature of the nip portion 31 is maintained at a predetermined fixing temperature. Control is in progress.

  The operation of the fixing device 30 having such a configuration will be described. In FIG. 2, when the image forming apparatus is activated and a print switch (not shown) is operated, energization of the heaters 41, 42, and 49 is started from a power supply (not shown) by a command from the control means 60, and each heater generates heat. This heat is transmitted to the fixing belt 36 by heating the heating roller 35 and the pressure rotator 33. When the control means 60 determines from the detection information from the non-contact temperature sensor 50 that the fixing belt 36 has been heated to a predetermined temperature required for fixing, the control means 60 energizes each heater so as to maintain the temperature. Is controlled. When the print switch is operated, a driving motor (not shown) is driven, and the fixing belt 36 is rotated counterclockwise in FIG. 2, and the rotating body 33 is driven to rotate clockwise.

  When the print switch is pressed, the image forming unit 3 transfers the toner image T onto the paper 11 as described above, and transports it in the transport path 23 toward the fixing device 30. The sheet 11 on which the unfixed toner image T has been transferred enters the casing 40 through the introduction port 40A and is guided to the nip portion 31 by the sheet guide member 45. Then, when the paper 11 passes through the nip portion 31, the unfixed toner T is heated and melted by heat and pressure and passes through the nip portion 31 while being fixed on the paper 11. At this time, the sheet 11 may adhere to the surface 36A of the fixing belt 36 due to melting of the toner, but the tip of the separation member 43 is disposed close to the fixing belt 36 leaving a gap that is narrower than the sheet thickness. Therefore, the sheet 11 attached to the fixing belt 36 is separated by the separating member 43. The paper 11A that has been separated or passed through the nip portion 31 without adhering to the fixing belt 36 passes between the separation member 43 and the paper guide member 46, passes through the casing 40 from the discharge port 40B, and passes through the paper discharge portion 21. Then, the paper is discharged to the paper discharge tray 22.

The fixing device 30 is removed from the image forming apparatus main body 1 during maintenance. In this case, both ends of the heaters 41 and 42 are detached from the main body ground terminal 403 and the power supply terminals 404 and 405 provided on the image forming apparatus main body 1 side. At this time, the power supply side terminal portion 41A, 42A is removed separately but to the power supply terminal 404 and 405, the ground-side terminal portion 41B, 42B are connected by the other end 401A of the ground terminal integrated portion 401 because, by removing the other end 401A of the ground terminal integrated portion 401 from the ground terminal 403, is coupled to the main body side terminal is released. In particular, when the ground terminal side is located on the mounting direction side (the back side of the main body) opposite to the direction in which the fixing device 30 is detached from the image forming apparatus main body 1, the number of terminals to be fastened or removed is reduced. This leads to a reduction in complexity.

  Further, since both ends of the heaters 41 and 42 are held by the heater support plates 406 and 407, they are not twisted even when the terminals are coupled or attached. For this reason, it is possible to prevent breakage due to twisting while ensuring workability during the attaching / detaching operation. Since the heaters 41 and 42 can keep the intervals at a rare interval by the heater support plates 406 and 407, the position in the heating roller 35, that is, the positional relationship with the inner peripheral surface of the roller is also stable. Uneven heating can also be reduced and good fixability can be obtained. Further, in the present embodiment, the heater support plates 406 and 407 are constituted by the casing 40 of the fixing device 30 or a bracket provided therein, so that the fixing device 30 can be easily attached and detached by removing each terminal. The fixing device 30 can be attached and detached, and the attaching / detaching workability of the fixing device 30 is improved.

In FIG. 7, the holding member is composed of insulating holders 420 and 421, and the conductor portion of each heater is substantially covered except for each terminal. As shown in FIG. 7B, the holders 420 and 421 include large-diameter portions 420A and 421A that are press-fitted into the inner peripheral surface of the pressure roller 35, and small-diameter portions 420B and 421B that are further outward in the axial direction. It has a cylindrical shape. One end 401 </ b > B that is a portion joined to the ground terminals 41 </ b > B and 42 </ b > B of the heaters 41 and 42 of the ground terminal integrated portion 401 is disposed in the holder 421. The small diameter portions 420B and 421B may be supported by the heater support plates 406 and 407 by forming support holes (not shown) in the heater support plates 406 and 407 shown in FIG.

Thus, the ground terminal integrated portion 401, one end 401 B that is bonded to the ground terminal of each heater by arranging in a holder 421, can be reduced conductive wire from the holder 421 until the heater terminal, It is possible to reduce breakage and deformation of the conductive wire and improve durability.

  In the above embodiment, both the heaters 41 and 42 are disposed inside the heating roller 35 around which the fixing belt 36 is wound, and the fixing belt 36 as a fixing rotator is heated. The arrangement is not limited to such a form. For example, as shown in FIG. 8, a hollow fixing roller 360 may be used as a fixing rotating body in which the pressure rotating body 33 is pressed to form the nip portion 31. The heaters 41 and 42 may be housed in the fixing roller 360 so as to generate heat without the fixing roller 360 and directly heat the fixing roller 360 as a fixing rotating body. That is, the configuration according to the present invention can be applied to both the belt fixing method and the roller fixing method, and the parts can be shared.

1 is a diagram illustrating a schematic configuration of a fixing device and an image forming apparatus using the same according to an embodiment of the present invention. FIG. 2 is an enlarged view showing a configuration example of a belt fixing type fixing device applied to the image forming apparatus of FIG. 1. It is an enlarged view showing a displacement state form of a rotating body arranged on the moving side in the fixing device. It is a figure which shows the structure of the heater single-piece | unit which shows an example of the heat source to which this invention was applied. It is a block diagram when the heater shown in FIG. 4 is inserted in the inside of a rotary body. It is a figure which shows the state which hold | maintained the heater with the holding member, and the connection state of each terminal. It is a figure which shows the form of the holding member which included the ground terminal integrated part of the heater. 1 is an enlarged view showing a configuration of a roller fixing type fixing device to which the present invention is applied. FIG. FIG. 3 is a block diagram illustrating a configuration of a control system that controls the fixing device.

Explanation of symbols

11 Recording material 11A Recording material 30 that has passed through the nip part Fixing device 31 Nip part 32 Fixing rotator 33 Pressing rotator 34, 360 Fixing roller 36 Fixing belt 41A, 42A Power supply side terminal part 41B, 42B Ground side terminal part 41, 42 heater 400 heating source 401 ground terminal integrated portion 401A other end (the portion that is joined to the ground terminal)
401B one end <br/> 403 body ground terminals 406, 407 holding members 420 and 421 holding member T unfixed toner image

Claims (4)

A fixing rotator and a pressure rotator that is in pressure contact with the fixing rotator, and a recording material onto which an unfixed toner image has been transferred are placed in a nip formed by the fixing rotator and the pressure rotator. Fixing the unfixed toner image on the recording material by passing through the fixing member provided detachably to the image forming apparatus main body ;
Each has a power supply side terminal portion and a ground side terminal portion, the ground side terminal portion is positioned on the mounting direction side of the image forming apparatus main body , and the power supply side terminal portion is positioned on the detaching direction side of the image forming apparatus main body. a plurality of heaters which one end is integrated without using a ground-side terminal and the fastening member of the plurality of heaters are connected to the body ground terminal to which the other end is positioned in the mounting direction side of the image forming apparatus main body The fixing rotating body is heated by having a ground terminal integrated portion connected thereto and energized with each power supply side terminal portion of the heater being connected to a power supply terminal provided on the detaching direction side of the image forming apparatus main body. A heating source to
A holding member that integrally holds the plurality of heaters;
One end of the ground terminal integrated part integrated with the ground side terminal part of the heater is disposed in the holding member. The fixing device according to claim 1.
The fixing device, wherein the fixing rotator is an endless fixing belt stretched between a fixing roller and a heating roller. The fixing device according to claim 1.
The fixing device, wherein the fixing rotator is a fixing roller.   An image forming apparatus comprising the fixing device according to claim 1.

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