JP5530947B2 - Fixing apparatus and image forming apparatus equipped with the same - Google Patents

Description

  The present invention relates to a fixing device for fixing unfixed toner on a paper surface by heating and pressing. The present invention also relates to an image forming apparatus such as a copying machine, a printer, or a facsimile equipped with the fixing device.

  In an image forming apparatus such as a copying machine, a printer, or a facsimile, a thermal fixing method is widely used as a method for fixing an unfixed toner image transferred onto a sheet by a transfer unit. In the thermal fixing method, two rotating members composed of a roller and a belt are brought into pressure contact with each other to form a nip. In the thermal fixing method, one or both of the rotating members are heated as a heated body using a heating body, and the toner carrying the unfixed toner image is inserted into the nip to fix the toner on the paper. . As a fixing device of the thermal fixing system, a roller that directly contacts a toner image of a sheet of two rollers constituting a pair of rollers that are in pressure contact with each other is used as a heating roller, and a heating body such as a halogen lamp is provided on the heating roller. The built-in one is common.

  Here, there is a concern that the fixing device may have a problem that the surface temperature of the object to be heated rises to an unintended high temperature. If the surface temperature of the heated body rises to an abnormally high temperature, the heated body may be damaged, or the components around the heated body may be adversely affected. In addition, the paper inserted through the nip may be burned out.

  In order to solve such a problem, a fixing device capable of preventing the surface temperature of the object to be heated from rising to an abnormally high temperature has been proposed. The fixing device described in Patent Document 1 monitors the surface temperature of the heating roller by a temperature rising safety device configured by a thermostat which is a kind of temperature sensor. In this conventional fixing device, the surface temperature of the heating roller is prevented from rising to an abnormally high temperature by shutting off the power to the heater using a thermostat before the heating roller is overheated.

JP 2007-33706 A

  However, in the fixing device described in Patent Document 1, since the thermostat wiring is housed in the housing recess close to the heating roller, the wiring may be exposed to a high temperature. As a result, there is a concern that the wiring may be burned out, which causes anxiety about the safety of the fixing device. Therefore, it is necessary to increase the heat resistance of the entire wiring in advance, which may increase the cost of the fixing device.

  In order to prevent the temperature of the wiring from rising, it is conceivable to send wind into the housing recess in which the wiring is housed. However, since the housing recess is close to the heating roller, there is a risk that the wind hits the heating roller. Thereby, there is a possibility that the heating roller cannot be raised to the fixing temperature or cannot be maintained at an appropriate temperature. As a result, sufficient performance as a fixing device cannot be exhibited, and there is a concern that poor fixing of the toner image may occur.

  The present invention has been made in view of the above points, and it is possible to suppress as much as possible the exposure of the electric wire for the temperature detection unit of the heated body in the fixing device to high temperature, thereby improving safety. It is an object of the present invention to provide a fixing device. It is another object of the present invention to provide an image forming apparatus equipped with such a fixing device and improved in safety.

  In order to solve the above problems, the fixing device of the present invention includes a heating body, a temperature detection unit for detecting the temperature of the heated body heated by the heating body, the heating body, the heated body, and the heating body. A housing for storing a temperature detection unit; a detection unit installation chamber provided in the housing for installing the temperature detection unit; and the object to be heated of the housing for wiring an electric wire used in a fixing device In contrast, a wiring chamber provided at an outer location across the detection unit installation chamber is provided.

  According to this configuration, since the wiring chamber is provided at a location separating the detection unit installation chamber from the heated object in order to wire the electric wire, most of the electric wires are separated from the heated object by the amount of the detection unit installation chamber. Will be separated. Therefore, most of the electric wires are not easily affected by the heat generated by the heated object, and exposure to high temperatures is suppressed. Furthermore, even when wind is sent into the wiring chamber in order to prevent an increase in the temperature of the electric wire, the wind is suppressed from flowing into the portion to be heated.

  Further, in the fixing device having the above configuration, the wiring chamber is provided adjacent to the outer periphery of the housing.

  According to this configuration, since heat dissipation from the outer surface of the housing can be expected, the temperature rise of the wiring chamber, that is, the electric wire is further suppressed.

  Further, in the fixing device having the above-described configuration, the wiring chamber is covered with an outer wall on the outer side of the housing, and is provided at a position between the outer wall and the outer wall so as to extend from the outer wall. An isolation wall that forms a wiring space for the electric wire is provided.

  According to this configuration, since the isolation wall is provided at a location between the wiring chamber and the heated body, the isolated wall serves as a heat insulating member against the heat of the heated body. Accordingly, the electric wire is further hardly affected by heat, and exposure to high temperatures is suppressed.

  Further, in the fixing device having the above configuration, the wiring chamber is provided between a distal end side extending from the outer wall of the isolation wall and an inner surface of the outer wall to prevent the electric wire from being detached from the wiring space. A plurality of guide pieces are provided for this purpose.

  According to this configuration, since the plurality of guide pieces prevent the electric wires from being detached from the wiring space, an effect of retaining the electric wires in the wiring chamber can be obtained. Therefore, the temperature rise of the electric wire is further suppressed.

  Further, in the fixing device having the above-described configuration, the plurality of guide pieces include one of the two adjacent guide pieces, the one guide piece extending from the distal end side of the isolation wall toward the inner surface of the outer wall, The other guide piece extends from the inner surface of the outer wall toward the isolation wall and extends substantially in parallel with each other, and the tip end portion of the one guide piece is located closer to the root side than the tip end portion of the other guide piece. It was decided.

  According to this configuration, when viewed from the direction in which the electric wire extends, the leading end portions of the guide pieces extending from both the isolation wall and the outer wall are overlapped, so that the electric wire is further caught from the overlapping portion and further from the wiring chamber. It becomes difficult to detach. Therefore, the effect | action which keeps an electric wire in a wiring chamber is improved, and the temperature rise of an electric wire is suppressed further.

  In the fixing device having the above-described configuration, the plurality of guide pieces have one surface on the wiring space side substantially in the same plane.

  According to this structure, it can wire so that an electric wire may extend straightly in a wiring chamber. Therefore, it becomes difficult for the electric wire to be detached from the wiring chamber, and it can be expected to prevent the electric wire from being worn out, which may occur when the electric wire is always bent.

  In the present invention, the fixing device having the above configuration is mounted on the image forming apparatus.

  According to this configuration, in the fixing device of the image forming apparatus, the electric wire of the temperature detection unit of the heated object is hardly affected by the heat generated by the heated object, and exposure to a high temperature is suppressed.

  According to the configuration of the present invention, it is possible to suppress as much as possible the exposure of the electric wire for the temperature detection unit for the object to be heated in the fixing device to a high temperature, and to provide a fixing device that is improved in safety. can do. In addition, it is possible to provide an image forming apparatus equipped with such a fixing device and improved in safety.

1 is a schematic vertical sectional front view of an image forming apparatus equipped with a fixing device according to an embodiment of the present invention. FIG. 2 is a vertical sectional front view of the fixing device shown in FIG. 1. FIG. 2 is a perspective view of a fixing device of the image forming apparatus shown in FIG. 1. FIG. 4 is a partially enlarged perspective view of the fixing device shown in FIG. 3. FIG. 4 is a partial top view of the fixing device shown in FIG. 3. FIG. 3 is a partially enlarged front view of a vertical cross section of the fixing device shown in FIG. 2.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, an image output operation of an image forming apparatus equipped with a fixing device according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic vertical sectional front view of an image forming apparatus. In FIG. 1, solid arrows indicate the paper conveyance path and conveyance direction, and alternate long and short dash arrows indicate the laser beam L.

  As shown in FIG. 1, a paper feed cassette 3 is disposed below the inside of the main body 2 of the image forming apparatus 1. The paper feed cassette 3 stores and accommodates paper P such as cut paper before printing. The sheets P are separated and sent one by one toward the upper left of the sheet feeding cassette 3 in FIG. The paper feed cassette 3 can be pulled out horizontally from the front side of the main body 2.

  A paper transport unit 4 is provided inside the main body 2 and to the left of the paper feed cassette 3. The paper transport unit 4 is formed substantially vertically along the left side surface of the main body 2. The paper transport unit 4 receives the paper P sent out from the paper feed cassette 3 and transports the paper P vertically upward along the left side surface of the main body 2 to the transfer unit 5.

  On the other hand, a document conveying device 6 is mounted on the upper surface of the main body 2 of the image forming apparatus 1, and an image reading unit 7 is mounted in the main body 2 below the main body 2. When a user copies an original, the original on which an image such as a character, figure, or pattern is drawn is stacked on the original conveying device 6 or placed on a contact glass (not shown) on the upper surface of the image reading unit 7. Or In the document conveying device 6, the documents are separated one by one and sent out, and the image is read by the image reading unit 7. An image is read by scanning light in the image reading unit 7 on the document on the contact glass.

  The reading of the document image and the start of printing are executed using the operation panel 8 provided at the upper part of the main body 2 and on the front side of the image reading unit 7. The operation panel 8 accepts settings such as the printing conditions such as the type and size of the paper P used for printing by the user, enlargement / reduction, and presence / absence of double-sided printing, and notifies the user of precautions and error messages. To do.

  Information on the image data of the original is sent to the exposure unit 9 disposed above the paper feed cassette 3 and in the center of the main body 2. The exposure unit 9 irradiates the image forming unit 10 with laser light L controlled based on the image data.

  An image forming unit 10 and a transfer unit 5 are provided above the paper transport unit 4 and to the left of the exposure unit 9. In the image forming unit 10, an electrostatic latent image of a document image is formed by the laser light L emitted from the exposure unit 9, and a toner image is developed from the electrostatic latent image. The toner is supplied to the image forming unit 10 from a toner container 11 provided above the exposure unit 9. The toner image formed by the image forming unit 10 is transferred by the transfer unit 5 to the pre-printing paper P sent in synchronization by the paper transport unit 4.

  A fixing device 20 is provided above the transfer unit 5. The paper P carrying the unfixed toner image in the transfer unit 5 is sent to the fixing device 20, and the toner image is heated and pressed by the heat roller 21 and the pressure roller 22 to be fixed.

  A paper guide unit 12 is provided above the fixing device 20. The paper P discharged from the fixing device 20 is discharged from the paper guide portion 12 to the in-body paper discharge portion 13 provided in the upper cylinder of the image forming apparatus 1 when double-sided printing is not performed.

  The discharge port portion from which the paper P is discharged from the paper guide portion 12 toward the in-body paper discharge portion 13 functions as a switchback portion 14. When performing double-sided printing, the switchback unit 14 switches the transport direction of the paper P discharged from the fixing device 20. Then, the paper P passes through the paper guide unit 12, is sent downward through a double-sided printing paper conveyance path 15 provided on the left side of the fixing device 20 and on the left side of the transfer unit 5, and again passes through the paper conveyance unit 4. It is sent to the transfer unit 5.

  Next, the detailed configuration of the fixing device 20 will be described with reference to FIGS. 2 to 6 in addition to FIG. 2 is a front view in vertical section of the fixing device, FIG. 3 is a perspective view of the fixing device, FIG. 4 is a partially enlarged perspective view of the fixing device, FIG. 5 is a partial top view of the fixing device, and FIG. It is an enlarged front view. Note that drawing of the pressure roller is omitted in the fixing device in FIG.

  As shown in FIGS. 1 to 3, the fixing device 20 includes a heat roller 21 and a pressure roller 22 inside the housing 30. The heat roller 21 and the pressure roller 22 are brought into pressure contact with each other with a predetermined pressure, and form a fixing nip having a predetermined width in the sheet conveyance direction. The sheet P carrying unfixed toner passes through the fixing nip.

  The heat roller 21 is driven to rotate by driving means (not shown). The pressure roller 22 rotates in accordance with the rotation of the heat roller 21 by being in contact with the heat roller 21. In a normal fixing operation, the heat roller 21 is rotated clockwise and the pressure roller 22 is counterclockwise so that the unfixed toner on the surface of the sheet P is fixed while the sheet P is conveyed from the lower side to the upper side in FIGS. Rotate clockwise.

  The heat roller 21 includes, for example, silicon rubber that forms an elastic member layer on the surface of a core member made of an aluminum tube having a diameter of 40 mm. On the surface of the elastic member layer, for example, a release layer such as PFA (tetrafluoroethylene-per-fluoroalkyl vinyl ether copolymer) or other fluorine-based resin is provided in close contact to improve smoothness and toner release properties. Yes.

  The pressure roller 22 includes, for example, sponge silicon rubber that constitutes an elastic member layer on the outside of a metal core made of stainless steel.

  Further, in the vicinity of the heat roller 21, as shown in FIGS. 2 to 5, a heater 23 which is a heating body and a temperature detection unit 24 are provided.

  The heater 23 is composed of, for example, a halogen lamp or the like, and is disposed inside the heat roller 21 that is a heated object. The heater 23 is a heating body that heats the heat roller 21 from the inside. The heater 23 has a rod shape extending in the axial direction of the heat roller 21, and for example, two heaters 23 are arranged in the vertical direction. The heat generated from the heater 23 is transmitted through the core material and elastic member layer of the heat roller 21 to reach the surface, and the heat on the surface of the heat roller 21 melts the unfixed toner carried on the paper P.

  The temperature detection unit 24 is disposed outside the heat roller 21 at two locations, that is, a substantially central portion in the axial direction of the heat roller 21 and the vicinity of one end. The temperature detection unit 24 is configured by a functional member, for example, a thermostat, for detecting the surface temperature of the heat roller 21 and controlling heating by the heater 23, and is disposed at a predetermined distance from the surface of the heat roller 21. The thermostat which is the temperature detection unit 24 is electrically connected in series between the heater 23 and its power supply (not shown). A bimetal is used for the thermostat, and when the surface temperature of the heat roller 21 reaches an abnormal temperature, the bimetal is deformed, the internal switch is turned OFF, and the energization to the heater 23 is forcibly cut off.

  The housing 30 is provided with a detection unit installation chamber 31 for installing a thermostat as the temperature detection unit 24. The detection unit installation chamber 31 is provided in a space adjacent to the heat roller 21 in the housing 30. The detection unit installation chamber 31 includes an opening 31 a through which the temperature detection unit 24 communicates toward the heat roller 21. And the terminal part 24a which the temperature detection part 24 has, and some electric wires 25, such as a harness connected to the terminal part 24a, are accommodated in the detection part installation chamber 31. FIG.

  Further, the housing 30 includes a wiring chamber 32 for wiring an electric wire 25 such as a harness connected to the temperature detection unit 24. In the present embodiment, the electric wire stored in the wiring chamber 32 is described as the electric wire 25 connected to the temperature detection unit 24, but other electric wires used in the fixing device 20 are stored in the wiring chamber 32. Sometimes it is done. In some cases, the wires stored in the wiring chamber 32 do not appear outside the wiring chamber 32 over the entire region between both ends of the heat roller 21.

  As shown in FIGS. 2, 5, and 6, the wiring chamber 32 is provided at a location outside the detection roller installation chamber 31 with respect to the heat roller 21 of the housing 30, and extends in the axial direction of the heat roller 21. Yes. As a result, most of the wires 25 except the portion wired in the detection unit installation chamber 31 are separated from the heat roller 21 by the amount of the detection unit installation chamber 31. Therefore, most of the electric wires 25 are hardly affected by the heat generated by the heat roller 21 and are not exposed to high temperatures. Further, even when wind is sent into the wiring chamber 32 in order to prevent the temperature of the electric wire 25 from rising, it is possible to suppress the wind from flowing into the heat roller 21.

  The wiring chamber 32 is provided adjacent to the outer periphery of the housing 30. Thereby, since the heat radiation from the outer surface of the housing 30 can be expected, the temperature rise of the wiring chamber 32, that is, the electric wire 25 is further suppressed.

  As shown in FIG. 6, the wiring chamber 32 is covered with an outer wall 32 a on the outer side with respect to the housing 30, and has an isolation wall 32 b on the inner side. The outer side wall 32a is formed in an L shape from the right side to the lower side in FIG. 6 of the wiring chamber 32 when viewed from the direction in which the electric wires 25 extend, that is, the direction perpendicular to the paper surface of FIG. The isolation wall 32b extends upward from the lower outer wall 32a in FIG. 6 of the wiring chamber 32 and is provided at a location between the heat roller 21 and forms a wiring space S for the electric wire 25 between the outer wall 32a. Yes. Thereby, the cross-sectional shape regarding the direction where the electric wire 25 is extended has comprised the rectangle in the wiring space S. FIG. Thus, since the isolation wall 32b is provided in the location between the wiring chamber 32 and the heat roller 21 that is the heated body, the isolation wall 32b serves as a heat insulating member against the heat of the heat roller 21. Therefore, the electric wire 25 becomes less susceptible to heat and is prevented from being exposed to high temperatures.

  The wiring chamber 32 includes a plurality of guide pieces 32c for preventing the electric wires 25 from being detached from the wiring space S. As shown in FIGS. 4 to 6, the guide piece 32c is provided between the distal end side 32d extending from the outer wall 32a of the isolation wall 32b and the inner surface of the outer wall 32a. The guide piece 32 c has a rectangular cross-section protruding from the wall surface of the wiring chamber 32, and its tip is curved toward the wiring space S. When the electric wire 25 is accommodated in the wiring space S of the wiring chamber 32, the electric wire 25 is accommodated between the tip of the guide piece 32 c and the wall surface of the wiring chamber 32 ahead of the guide piece 32 c, as shown by the solid line arrow in FIG. 6. Since the plurality of guide pieces 32c having such a configuration prevent the electric wires 25 from being detached from the wiring space S, an effect of retaining the electric wires 25 in the wiring chamber 32 can be obtained. Therefore, the temperature rise of the electric wire 25 is further suppressed.

  Of the two adjacent guide pieces 32c, one guide piece 32c extends from the distal end side 32d of the isolation wall 32b toward the inner surface of the outer wall 32a facing the isolation wall 32b, and the other guide piece 32c is It extends toward the isolation wall 32b from the inner surface of the outer side wall 32a. The guide pieces 32c extend substantially in parallel with each other, and the tip end portion of one guide piece 32c is located closer to the root side than the tip end portion of the other guide piece 32c. Thereby, when viewed from the direction in which the electric wire 25 extends as shown in FIG. 6, since the tip portions of the guide pieces 32 c extending from both the isolation wall 32 b and the outer wall 32 a overlap, the electric wire 25 overlaps. It becomes difficult to detach from the wiring chamber 32 by being caught in the place. Therefore, the effect | action which keeps the electric wire 25 in the wiring chamber 32 is heightened, and the temperature rise of the electric wire 25 is suppressed further.

  Further, as shown in FIG. 6, the plurality of guide pieces 32c are present in substantially the same plane along the direction in which the electric wire 25 extends, that is, the direction perpendicular to the paper surface of FIG. It was decided. Thus, the wiring 25 can be wired so as to extend straight in the wiring chamber 32. Therefore, the electric wire 25 is further less likely to be detached from the wiring chamber 32, and it can be expected to prevent wear of the electric wire 25 that may occur when the electric wire 25 is always bent.

  According to the structure of the said embodiment, it is possible to suppress as much as possible that the electric wire 25 for the temperature detection part 24 with respect to the heat | fever roller 21 in the fixing device 20 is exposed to high temperature, and the improvement of safety was achieved. The fixing device 20 can be provided. Further, it is possible to provide the image forming apparatus 1 equipped with such a fixing device 20 and improved in safety.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  For example, in the above embodiment, a thermostat is taken as an example of the temperature detection unit 24, but the temperature detection unit 24 is not limited to a thermostat, and the surface temperature of the heat roller 21 is detected and heated by the heater 23. Any other functional member may be used as long as the function is controlled. For example, the temperature detection unit 24 may be a thermistor that is a temperature sensor.

  In the above-described embodiment of the present invention, the image forming apparatus for monochrome printing using only black toner as the image forming apparatus 1 has been described as an example. However, the image forming apparatus to which the invention is applied is described above. It is not limited to the model, and may be a tandem type or rotary type image forming apparatus for color printing that includes an intermediate transfer belt and can superimpose a plurality of colors to form an image.

  The present invention can be used in a fixing device that needs to wire an electric wire around a heat roller.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 20 Fixing apparatus 21 Heat roller 22 Pressure roller 23 Heater 24 Temperature detection part 25 Electric wire 30 Housing 31 Detection part installation room 32 Wiring room 32a Outer side wall 32b Isolation wall 32c Guide piece 32d End side 32e (of isolation wall) 32e One side of guide piece S Wiring space

Claims (6)

A heating element;
A temperature detection unit for detecting the temperature of the heated body heated by the heating body;
A housing that houses the heated body, the heated body, and the temperature detection unit;
A detection unit installation chamber provided in the housing for installing the temperature detection unit;
In order to route the electric wire used in the fixing device, it is located on the outside of the housing with respect to the object to be heated and separated from the detection unit installation chamber and adjacent to the inside of the outer wall constituting the outer periphery of the housing. and wiring chamber provided Te,
A fixing device comprising: The wiring chamber is covered with the outer wall on the outside of the housing, and is provided at a location between the outer wall and the heated body to form a wiring space for the electric wire between the outer wall and the wiring chamber. The fixing device according to claim 1, further comprising an isolation wall . The wiring chamber includes a plurality of guide pieces provided between a distal end side of the isolation wall extending from the outer wall and the inner surface of the outer wall to prevent the electric wire from being detached from the wiring space. The fixing device according to claim 2. Among the two guide pieces adjacent to each other, one of the guide pieces extends from the distal end side of the isolation wall toward the inner surface of the outer wall, and the other guide piece is the outer wall. 4. The apparatus according to claim 3, wherein the guide portion extends from an inner surface toward the isolation wall and extends substantially parallel to each other, and a tip portion of the one guide piece is present on a base side from a tip portion of the other guide piece. The fixing device described. 5. The fixing device according to claim 3 , wherein one surface of the plurality of guide pieces on the wiring space side is substantially in the same plane . An image forming apparatus comprising the fixing device according to claim 1.