JP2005352111A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having a pressure member for fixing which is inexpensive and is constituted to be easily replaced in order to cope with the kind of paper having different property. <P>SOLUTION: In the image forming apparatus having a fixing device where a nip part is formed by bringing two rotating bodies, at least either of which is constituted to be belt-shaped, into press-contact with each other, which is equipped with a heating source for heating at least either of the two rotating bodies, and a driving source for driving and rotating at least either of the two rotating bodies, and which fixes a toner image on transfer material by making the transfer material pass through the nip part, a pressure member for pressing the belt-shaped rotating body against the other rotating body is constituted so that it can press-fit to the belt-shaped rotating body and its press-fit thereto can be released, and the pressure member is replaced in a press-fit releasing state. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine having a toner image fixing device, a printer, a FAX, and the like. The present invention relates to an image forming apparatus having a fixing device.

  In a conventional fixing device, there is a method in which a transfer material holding a toner image is passed through a nip formed by pressing rollers, which are two rotating bodies, and heated and pressed to fix the toner image on the transfer material. It is common.

  In the case of a color image forming apparatus, the amount of toner adhering to the transfer material increases, which causes a problem that the transfer material easily winds around the rotating body when the toner image is heated and pressed. Therefore, the nip shape is concave on the side of the rotating body that contacts the unfixed toner image. In such a case, it is necessary to make the hardness of the roller that does not contact the toner image on the back side of the transfer material somewhat higher than the hardness of the roller that contacts the unfixed toner image. When fixing a transfer material with poor fixability that can not secure the necessary nip width, it is possible to increase the fixing temperature or decrease the process speed, resulting in a longer warm-up time, There arises a problem that print productivity is lowered. In addition, a transfer material having high rigidity such as thick paper has a problem that the shape when discharged after the fixing device follows the nip shape, and the curl becomes large. Since the cardboard has high rigidity and it is not necessary to make the nip shape convex on the roller side where the unfixed toner image comes into contact, the hardness of the roller on the back side of the transfer material is lowered to ensure the nip width, and the curl is Although it is possible to make the nip portion flat so as to be small, under such conditions, there arises a problem that the thin paper is wound around the roller on the unfixed toner image side.

  In response to the problem that the combination of one type of roller pair as described above cannot be applied to various transfer materials, a) the optimum roller temperature, diameter, peripheral speed, and surface depending on the moisture content, thickness, etc. of the transfer material A technique for making it possible to select conditions such as hardness using a plurality of rollers (for example, see Patent Document 1), b) Wrinkle of an envelope carrying a toner image or color toner image on OHT (transparent paper) A technique for selecting a roller according to the type of transfer material (for example, see Patent Document 2) has been disclosed for measures such as ensuring transparency.

Furthermore, c) at least one of the two rotating bodies has a belt shape, and includes a plurality of pressure members that press the belt-shaped rotating body against the other rotating body, and automatically adds a plurality of pressure members according to the conditions of the transfer material. A mechanism comprising a mechanism for moving and stopping one of the pressure members to the nip portion and its control means is also conceivable.
JP 54-95246 A Japanese Patent Laid-Open No. 4-166878

  However, the above Patent Documents 1 and 2 have a problem that the temperature of a plurality of rollers must be controlled at the same time, and the power consumption during standby is very large. If the temperature control of multiple rollers is omitted to reduce power consumption during standby, it takes time until the temperature of the rollers rises after the rollers are switched, and the first printout takes a long time. Occurrence is also a concern. Furthermore, if the roller is controlled so as to decrease the peripheral speed, the print productivity also decreases. Therefore, simply providing rollers with different temperatures, diameters, peripheral speeds, and surface hardnesses and switching according to the situation causes problems that the waiting time at the time of switching and the productivity of printing decrease.

  Furthermore, the method c) has the disadvantages that the structure and control are complicated and the cost is high.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus including a fixing pressure member having a structure that can be easily replaced at low cost in order to cope with transfer materials having different properties.

  Two rotators each having at least one belt shape are pressed against each other to form a nip portion, a heating source for heating at least one of the two rotators, and at least one of the two rotators An image forming apparatus having a fixing device that fixes a toner image on the transfer material by passing the transfer material through the nip portion, and the belt-shaped rotary member is replaced with the other rotary member. An image forming apparatus, wherein a pressure member that presses against a belt-shaped rotating body can be crimped and released, and the pressure member can be replaced in a pressure release state.

  In addition to the advantages of a low-cost and simple mechanism configuration, the pressure member can be replaced while the temperature control of the heating source is continued. Therefore, even after replacement of the pressure member, warm-up time is not required and power consumption can be reduced.

  First, a fixing device according to the present invention and an image forming apparatus on which the fixing device is mounted will be described.

  In the description of the embodiment of the present invention, the technical scope of the present invention is not limited by the terms used in this specification.

  FIG. 1 is a schematic diagram illustrating an example of the overall configuration of the image forming apparatus.

  In FIG. 1, 10 is a photoconductor, 11 is a scorotron charger as charging means, 12 is a writing device as image writing means, 13 is a developing device as developing means, and 14 is for cleaning the surface of the photoconductor 10. A cleaning device, 15 a cleaning blade, 16 a developing sleeve, and 20 an intermediate transfer belt. The image forming unit 1 includes a photoconductor 10, a scorotron charger 11, a developing unit 13, a cleaning device 14, and the like. Since the mechanical configuration of the image forming unit 1 for each color is the same, in FIG. Reference numerals are given to configurations of only the (yellow) series, and reference symbols are omitted for the constituent elements of M (magenta), C (cyan), and K (black).

  The arrangement of the image forming means 1 for each color is in the order of Y, M, C, K with respect to the running direction of the intermediate transfer belt 20, and each photoconductor 10 contacts the stretched surface of the intermediate transfer belt 20. The contact point rotates in the same direction as the traveling direction of the intermediate transfer belt 20 and at the same linear speed.

  The intermediate transfer belt 20 is stretched around a driving roller 21, an earth roller 22, a tension roller 23, a static elimination roller 27, and a driven roller 24. Configure.

  The intermediate transfer belt 20 is driven by rotation of the driving roller 21 by a driving motor (not shown).

  The photosensitive member 10 is formed by forming a photosensitive layer such as a conductive layer, an a-Si layer, or an organic photosensitive member (OPC) on the outer periphery of a cylindrical metal base formed of, for example, an aluminum material, and the conductive layer is grounded. In the state, it rotates counterclockwise as indicated by the arrow in FIG.

  An electrical signal corresponding to the image data from the reading device 80 is converted into an optical signal by the image forming laser, and is projected onto the photoconductor 10 by the writing device 12.

  The developing unit 13 is a developing sleeve formed of a cylindrical nonmagnetic stainless steel or aluminum material that keeps a predetermined interval with respect to the circumferential surface of the photoconductor 10 and rotates in the same direction as the rotation direction of the photoconductor 10. 16.

The intermediate transfer belt 20 is an endless belt having a volume resistivity of 10 ⁶ to 10 ¹² Ω · cm. A semiconductive seamless belt having a thickness of 0.04 to 0.10 mm, in which a conductive material is dispersed.

  A transfer unit 25 has a function of transferring a toner image formed on the photoreceptor 10 onto the intermediate transfer belt 20 by applying a direct current having a polarity opposite to that of the toner. As the transfer unit 25, a transfer roller can be used in addition to the corona discharger.

  Reference numeral 26 denotes a transfer roller which can be brought into contact with and released from the earth roller 22 and retransfers the toner image formed on the intermediate transfer belt 20 onto the transfer material P.

  A cleaning device 28 is provided to face the driven roller 24 with the intermediate transfer belt 20 interposed therebetween. After the toner image is transferred to the transfer material P, the intermediate transfer belt 20 has the charge of the residual toner weakened by the neutralizing roller 27 to which an AC voltage superimposed with a DC voltage having the same or opposite polarity as that of the toner is applied. The toner remaining on the peripheral surface is cleaned. A fixing device 4 according to the present invention will be described in detail later.

  70 is a paper feed roller, 71 is a timing roller, 72 is a paper cassette, and 73 is a transport roller. 81 is a paper discharge roller, and 82 is a paper discharge tray. Reference numeral 85 denotes an operation panel. B1 is a control unit which is a control means.

  Here, the fixing device 4 according to the present invention will be described.

  The first embodiment is a method using the replaceable pressure pad shown in FIGS.

  FIG. 2 is a view for explaining a pressure-bonding mechanism of the pressure member.

  3 is a cross-sectional view taken along arrow XX in FIG.

  2A and 3 show a state where the pressure pad presses the heating roller 41 via the pressure belt and the transfer material.

  FIG. 2B is a diagram illustrating a state in which the pressure pad is released from pressure bonding.

  2 and 3, reference numeral 41 denotes a heating roller, and a heat-resistant layer 412 that is an elastic body is lined on a cylindrical cored bar 413 made of aluminum, and a release layer 411 is coated on the outer periphery of the heat-resistant layer 412. The heating roller 41 is heated to a predetermined temperature by a halogen heater 46 that is a heating source and is disposed in the cavity of the heating roller 41 via a support contact piece 461. Detected by a non-contact temperature sensor 414 installed near the surface and transmitted to the control unit B1, and the control unit B1 turns the halogen heater 46 on and off, so that the surface temperature of the heating roller 41 becomes a specified temperature. So that it is controlled.

  A belt drive roller 43 receives power from a drive source (not shown). 44 is a tension roller and 45 is a driven roller.

  47 is a pressure belt in which polyimide rubber is used as a base, a silicone rubber layer is formed on the outer surface, and a PFA resin thin layer is applied on the surface of the silicone rubber layer. The transfer material P carrying the received toner image is pressed against the heating roller 41 by the pressure belt 47 and the pressure pad A to fix the toner image on the transfer material P.

  Reference numeral 42 denotes a pad pressure-bonding mechanism as a pressure member, which includes a pad support member 420, a pressure pad A, a guide rail 423 into which the pad support member 420 is inserted, rail support plates 50A and 50B, a support plate rotating shaft 52, It consists of a release cam 51 that engages with the rail support plates 50A and 50B, a rotation restricting dowel 54, a crimp spring 53, and the like. The guide rail 423 is fixed to the rail mounting plates 50A and 50B on the fixing device frame bodies 4A and 4B side, and also serves as a stay. The rail support plates 50A and 50B rotate about the support cam rotation shaft 52 provided on the fixing device frame bodies 4A and 4B as a fulcrum, and the release cam 51 rotates by 180 ° with power from a drive source (not shown). As shown in FIG. 2B (dotted line in FIG. 2A), the pressure roller A is released from the heating roller 41, and at the same time, the tension roller 44 is Pulled in the direction of the arrow, the pressure belt 47 is stretched.

  The release cam 51 is attached to the drive shaft 51A supported on the fixing device frames 4A and 4B via a bearing (not shown) in the same phase and engages with the rail support plates 50A and 50B. The rail support plates 50A, 50B and 4A, 4B are provided with notches f, e, and k sufficient to insert the pad support member 420.

  FIG. 4 is a diagram showing a pressure pad alone.

  FIG. 5 is a view showing a rear end portion of the pad support member.

  4 and 5, the pressure pad A is bonded in the longitudinal direction to the groove M provided in the pad support member 420.

  A plurality of pad support members 420 are prepared according to the type of transfer material. The pressure pad A of each unit is made of materials different in at least one of hardness, heat capacity, thickness h (see FIG. 4) perpendicular to the belt traveling direction, or heat capacity distribution. Each pressure pad is configured such that a silicone rubber elastic member 422 is covered with a Teflon (registered trademark) sliding sheet 423.

  5A is a view seen from the direction of arrow F in FIGS. 2 and 3, and FIG. 5B is a side view thereof.

  In FIG. 5, a light transmission hole 424 is provided at the rear end m of the pad support member 420, and the position of the light transmission hole 424 varies depending on the type of the pressure pad, thereby identifying the type of the pressure pad A. Is done.

  That is, when the pad support member 420 is inserted along the guide rail 423, the abutting portion g of the pad support member 420 abuts on the rail mounting plate 50 and is positioned, and is fixed to the guide rail 423 by a clamp member (not shown). The The rear end portion m of the pad support member 420 protrudes from a notch hole k provided in the rail support plate 50B. The light transmission hole 424 engages with an optical sensor 435 attached to the fixing device frame 4B. Since the plurality of optical sensors 425 are provided at positions corresponding to the light transmission holes 424 of each unit, the type of the pressure pad A is identified by the control unit B1 according to the position where the light is detected. Further, the control unit B1 controls the temperature so that the optimum fixing temperature according to the type of the pressure pad A is obtained.

  Therefore, the operator may select and replace the pressure pad A (pad support member 420) corresponding to the transfer material to be used, and insert it at a predetermined position.

  If a transfer material P of different materials is used, the front door (not shown) is opened, and one of the pad support members is manually selected and inserted into the fixing device 4. The type of the transfer material P is identified by the optical sensor corresponding to the position, and the control temperature is automatically switched by the control unit B1. When the temperature reaches a desired value, printing is possible. When the print button is pressed in this state, power from a drive source (not shown) is obtained, the release cam 51 rotates 180 °, the crimp spring 53 pushes up the rail mounting plates 50A and 50B, and the rail mounting plate 50 rotates counterclockwise. At the same time, the pressure pad A 1 is pressed against the heating roller 41 via the pressure belt 47. Next, the heating roller 41 and the belt driving roller 43 are rotated to pass the transfer material P through the nip portion. After completion of the sheet passing, the rotation of the heating roller 41 and the belt driving roller 43 is stopped, the release cam 51 is rotated 180 °, and the pressure belt 47 is released from the heating roller 41 by pressure bonding.

  In the present invention, since the temperature control of the heating source of the heating roller 41 is not turned off, the pressure pad A1 can be released while the temperature is controlled in the same manner as in the standby mode, so the waiting time is short and the power consumption is small. There is an advantage that can be done. A cover is provided so that the hand does not touch the energizing portion of the halogen heater 46 when the front door is opened.

  The above mechanism is a method of preparing a plurality of pad support members 420 on which the pressure pads A are mounted and manually replacing the pad support members 420 according to the type of transfer material. Will be described.

  FIG. 6 is a diagram showing a turret type pressure pad.

  FIG. 7 is a diagram showing a cross section taken along the arrow YY in FIG. 6, a positioning member, and a position detection unit.

  FIG. 6A shows a state in which the pressure pad presses the heating roller 41 via the pressure belt and the transfer material.

  FIG. 6B is a diagram illustrating a state in which the pressure pad is released from pressure bonding.

  7A shows a YY arrow cross section, FIG. 7B shows a positioning member, and FIG. 7C shows a position detection unit.

6 and 7, members having the same functions as those in FIG. 1 are denoted by the same reference numerals.
6 and 7, reference numeral 41 denotes a heating roller, and a heat-resistant layer 412 that is an elastic body is lined on a cylindrical cored bar 413 made of aluminum, and a release layer 411 is coated on the outer periphery of the heat-resistant layer 412. The heating roller 41 is heated to a predetermined temperature by a halogen heater 46 that is a heating source and is disposed in the cavity of the heating roller 41 via a support contact piece 461. Detected by a non-contact temperature sensor 414 installed near the surface and transmitted to the control unit B1, and the control unit B1 turns the halogen heater 46 on and off, so that the surface temperature of the heating roller 41 becomes a specified temperature. So that it is controlled.

  A belt drive roller 43 receives power from a drive source (not shown). A tension roller 44 moves in the direction of the arrow and applies tension to the pressure belt 47. 45 is a driven roller.

  47 is a pressure belt in which polyimide rubber is used as a base, a silicone rubber layer is formed on the outer surface, and a PFA resin thin layer is applied on the surface of the silicone rubber layer. The transfer material P holding the received toner image is pressed against the heating roller 41 by the pressure belt 47 and the pressure pad A1, which is a pressure member, to fix the toner image on the transfer material P.

  Reference numeral 42 denotes a pad pressure bonding mechanism which is a pressure member, which is a cylindrical pad support member 420, pressure pads A1, A2, A3, A4, shaft support plates 50C, 50D, a release cam 51, a pressure spring 53, and rotation regulation. It consists of a dowel 54 and the like. The pad support member 420 is made of a rigid material, has a plurality of grooves M in the longitudinal direction, and pressure pads A1 to A4 are mounted in the grooves M.

  Each of the pressure pads A1 to A4 is configured to have at least one of hardness, heat capacity, thickness in the direction perpendicular to the traveling direction of the pressure belt, or distribution of heat capacity.

  The pad support member 420 preferably has a lower thermal conductivity. The pad support member 420 is integrally formed with a rotating shaft 425 that is manually rotated. The rotary shaft 425 is horizontally mounted on the shaft support plates 50C and 50D via the bearing 430. The shaft support plates 50C and 50D are integrated by a stay (not shown) that passes through an escape hole (not shown) of the fixing device frames 4A and 4B. The shaft support plates 50C and 50D have the support cam rotation shaft 52 provided on the fixing device frames 4A and 4B as a fulcrum, and the release cam 51 rotates 180 ° by power from a drive source (not shown). As shown by the dotted lines of the plates 50C and 50D, the pressure pad A1 is released from the heating roller 41 against the pressure spring 53. The release cam 51 is attached to the drive shaft 51A supported on the fixing device frames 4A and 4B via a bearing (not shown) in the same phase, and engages with the shaft support plates 50C and 50D.

  A positioning ring 427 having a positioning V-groove n is fitted to the rotary shaft 425, and the V-groove n engages with the click member 49 disposed on the shaft support plates 50C and 50D and the release cam 51. Then, the pressure positions of the pressure members A1 to A4 and the heating roller 41 corresponding to the type of transfer material are regulated.

  In the nip portion T formed by the pressure pads A1 to A4, the pressure, the nip length, etc. are different from each other, and the fixing conditions are also different.

  Reference numeral 429 denotes a rotation knob for manual rotation integrated with the rotation shaft 425. Further, the rotary shaft 425 has a hub 431 integrated with a light shielding plate 432 having a slit q at the end opposite to the knob 429, and the V groove n (four in this embodiment) and the slit q. Are installed synchronously. The slits q engage with a plurality of optical sensors 425 (four in this embodiment) attached to the fixing device frame 4B.

  That is, the rotary knob 429 is rotated, the pressure pad corresponding to the transfer material is selected via the pressure belt 47, and the position of the pressure pad and the heating roller 47 is determined by engaging with the click member 49. The At the same time, the position of the slit q is synchronized with the pressure pad and the light shielding plate 432, the optical sensor 435 is turned on, and the control unit B1 is controlled to automatically switch the temperature control.

  In the embodiment, four pressure pads A1 to A4 are carried, but an optical sensor corresponding to the number of pressure pads may be provided.

  As a procedure for replacing the pressure pad in the present embodiment, when the operator presses the transfer material selection button corresponding to the material on the operation panel 85 (see FIG. 1), the pressure pad corresponding to the transfer material is applied. Instructions are displayed. At the same time, power from a drive source (not shown) is obtained, the release cam 51 rotates 180 °, and the shaft support plates 50C and 50D are pushed down against the pressure spring 53, and the shaft support plates 50C and 50D rotate the support plate. The pressure pad releases the pressure contact with the pressure belt 47 and the heating roller 41 at the same time as it rotates clockwise with the shaft 52 as a fulcrum. The positions of the pressure pads A to A4 are displayed on the entire surface S of the rotary knob 429. The operator can then open the front door and rotate the rotary knob 429 to replace the indicated pressure pad. At this time, the light shielding plate 432 is engaged with the optical sensor 435 corresponding to the transfer material to be used, and the control temperature is automatically switched by the control unit B1. When the temperature reaches a desired value, a printable display is displayed. When the print button is pressed, the release cam 51 rotates 180 °, and then the heating roller 41 and the belt driving roller 43 rotate, and the transfer material is transferred to the nip portion T. Pass through.

  Therefore, in this mechanism, it is not necessary to turn off the temperature control of the heating source of the heating roller 41, and the pressure pad can be released while the temperature is controlled simultaneously with the standby mode. There is an advantage that can be reduced.

  Next, the following method is also conceivable as a third embodiment.

  FIG. 8 is a diagram illustrating an example in which a pressure roller is pressure-bonded to a pressure pad that can be replaced via a heating belt, and pressure-bonding is released.

  This embodiment is based on the same temperature control, and there is a method of replacing the pressure pad that matches the material of the transfer material while the pressure pad is released from pressure bonding, but it is almost the same as the first embodiment. Description is omitted.

  In the above embodiment, the pressure pad matching the transfer material can be easily selected by a simple mechanism, and the pressure pad can be replaced while continuing the temperature control, so that an efficient fixing process is possible.

1 is a schematic diagram illustrating an example of an overall configuration of an image forming apparatus. It is a figure for demonstrating the crimping | compression-bonding mechanism of a pressurization member. It is sectional drawing of the XX arrow of FIG. It is a figure which shows a pressurization pad single-piece | unit. It is a figure which shows the rear-end part of a pad support member. It is a figure which shows a turret type pressure pad. It is a figure which shows the YY arrow cross section of FIG. 6, a positioning member, and a position detection part. It is a figure which shows the example which crimps | bonds a pressure roller to the pressure pad which can be replaced | exchanged via a heating belt, and cancels pressure bonding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 4 Fixing device 41 Heating roller 42 Pad crimping mechanism 47 Pressure belt 49 Click member 420 Pad support member 425 Optical sensor 427 Positioning ring 432 Light shielding plate 50A, 50B Rail support plate 50C, 50D Axis support plate 51 Release cam A , A1, A2, A3, A4 Pressure pad B1 Control unit

Claims (4)

Two rotators each having at least one belt shape are pressed against each other to form a nip portion, a heating source for heating at least one of the two rotators, and at least one of the two rotators An image forming apparatus having a fixing device that fixes a toner image on the transfer material by passing the transfer material through the nip portion, and the belt-shaped rotary member is replaced with the other rotary member. An image forming apparatus, wherein a pressure member that presses against a belt-shaped rotating body can be crimped and released, and the pressure member can be replaced in a pressure release state. The image forming apparatus according to claim 1, wherein the pressure member can be replaced in a state where the heating source is energized and the temperature is controlled. 2. A plurality of the pressure members for replacement comprising at least one of hardness, heat capacity, thickness in a direction perpendicular to the belt traveling direction and distribution of heat capacity, and made of different materials. 3. The image forming apparatus according to any one of 2 above. 4. The image forming apparatus according to claim 1, further comprising a control unit configured to control so that a control temperature of the heating source is automatically switched when the pressure member is replaced. 5.

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