JP2011085867A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that prevents deformation of an opening/closing cover without improving strength of the opening/closing cover, when installing a unit on an image forming apparatus body side of the opening/closing cover. <P>SOLUTION: When the opening/closing cover 214 is closed, at least a part of pressing force to be applied on a secondary transfer unit 10 is received by the image forming apparatus body 110 side. Specifically, when the opening/closing cover 214 is closed, a guide shaft 228 of the secondary transfer unit 10 enters a notch 232 of a guide member 230 on the image forming apparatus body 110 side. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus in which a unit such as a secondary transfer unit is installed on the image forming apparatus main body side of an opening / closing cover.

  In recent years, electrophotographic image forming apparatuses capable of forming multicolor images such as color copying machines and color printers have been developed.

  As an electrophotographic image forming apparatus, for example, a toner image for each color is formed on an image carrier such as a photosensitive drum, and the toner images for each color are sequentially superimposed on an intermediate transfer belt as an intermediate transfer member. After transferring and forming a multicolor image, the multicolor image is transferred to a recording paper as a transfer paper at the nip portion between the intermediate transfer belt and the transfer belt of the secondary transfer unit, and fixed to form an image. An intermediate transfer type color image forming apparatus is well known.

  In this intermediate transfer type color image forming apparatus, the secondary transfer unit is provided on the image forming apparatus main body side of the cover that can be opened and closed at the opening of the image forming apparatus main body, and when a paper jam occurs in the nip portion, The cover is opened to remove the jammed paper.

  In Patent Document 1, a secondary transfer roller is provided on the opening / closing cover, and when the opening / closing cover is closed, the shaft of the transfer roller is positioned so that the shaft of the transfer roller can be received and positioned by a guide guide provided on the intermediate transfer belt. It is disclosed that the transfer roller shaft is guided along a straight path connecting the drive roller shaft of the intermediate transfer belt.

JP 2004-20574 A

  By the way, in the image forming apparatus in which the secondary transfer unit is mounted on the image forming apparatus main body side of the opening / closing cover, the transfer pressure load is directly applied to the secondary transfer unit and the load is applied to the opening / closing cover. There was a risk that the open / close cover could be deformed when closed.

  For example, as shown in FIG. 11, if the pressing force (transfer pressure contact load) applied to the secondary transfer unit 1000 is 6 kg, the secondary transfer unit 1000 is provided on the image forming apparatus main body side as shown in FIG. A load of 3 kg is applied to the upper and lower sides of the mounted opening / closing cover.

  In order to increase the strength of the opening / closing cover, for example, it is necessary to prevent deformation by another member such as a metal frame. However, this leads to an increase in cost and weight, and in the worst case, a secondary transfer pressure may not be secured.

  Incidentally, in Patent Document 1, since the load of the transfer roller is applied to the opening / closing cover as it is, the opening / closing cover swells and the opening / closing cover itself must be strengthened to prevent it.

  Therefore, an object of the present invention is to provide an image forming apparatus that can prevent deformation of the opening / closing cover without increasing the strength of the opening / closing cover itself when the unit is installed on the image forming apparatus main body side of the opening / closing cover. It is to provide.

  In order to achieve the above object, an image forming apparatus according to the present invention is supported so as to be movable with respect to an image forming apparatus main body, an open / close cover that opens and closes an opening of the image forming apparatus main body, and image formation of the open / close cover An image forming apparatus comprising a unit swingably installed on the apparatus main body side, wherein at least part of the pressing force applied to the unit when the open / close cover is closed Including a pressing force bearing means for bearing on the side.

  According to the above configuration, when the opening / closing cover is closed, at least a part of the pressing force applied to the unit can be borne by the image forming apparatus main body, so the unit is installed on the image forming apparatus main body side of the opening / closing cover. In such a case, the opening / closing cover can be prevented from being deformed without increasing the strength of the opening / closing cover itself.

  Specifically, the pressing force bearing means is provided in the image forming apparatus main body, and a guide member in which a notch is formed on an extension of the movement trajectory of the unit when the opening / closing cover is closed, and the unit The guide shaft of the unit enters the notch of the guide member when the opening / closing cover is closed.

  According to the above configuration, since the guide shaft of the unit enters the notch of the guide member when the opening / closing cover is closed, it is possible to reliably bear at least part of the pressing force applied to the unit on the image forming apparatus main body side. it can.

  In the image forming apparatus, the opening direction of the notch of the guide member intersects the direction of the pressing force received by the unit.

  According to the above configuration, since the opening direction of the notch of the guide member intersects the direction of the pressing force received by the unit, the guide shaft of the unit does not come off the guide member when the opening / closing cover is closed. Therefore, a part of the pressing force received by the unit can be borne efficiently on the image forming apparatus main body side. In addition, there is no loss in the closing speed of the open / close cover.

  Further, in the image forming apparatus, the unit is swingable by being pivotally supported on one side with respect to the opening / closing cover and free on the other side.

  According to the above configuration, since the unit is swingable with respect to the opening / closing cover, the guide shaft of the unit is likely to enter the notch of the guide member.

  In one embodiment, the opening / closing cover is linearly movable in the horizontal direction with respect to the image forming apparatus main body.

  In another aspect, the opening / closing cover is rotatable about a fulcrum with respect to the image forming apparatus main body.

  Furthermore, in the image forming apparatus, the unit is a secondary transfer unit, and further includes an image carrier and an intermediate transfer unit that transfers the toner image on the surface of the image carrier to a sheet.

  According to the above configuration, since the transfer pressure contact load from the intermediate transfer unit is not applied to the opening / closing cover from the secondary transfer unit installed on the image forming apparatus main body side of the opening / closing cover, the opening / closing cover is not closed when the opening / closing cover is closed. There is no risk of deformation.

  Furthermore, in the image forming apparatus, when the open / close cover is closed, the secondary transfer unit is positioned above the transfer nip between the secondary transfer unit and the intermediate transfer unit, and below the transfer nip. Thus, the secondary transfer unit is supported by the guide member.

  According to the above configuration, when the open / close cover is closed, the secondary transfer unit is positioned above the transfer nip between the secondary transfer unit and the intermediate transfer unit, and the secondary transfer unit is guided below the transfer nip. Therefore, the load capacity for the pressing force applied to the secondary transfer unit on the image forming apparatus main body side is increased.

  In addition, in the image forming apparatus, a distance between the transfer nip and the point where the secondary transfer unit is supported by the guide member is a point that the transfer nip and the secondary transfer unit are held by the opening / closing cover. And longer than the distance.

  In the above configuration, the longer the distance between the transfer nip and the point where the secondary transfer unit is supported by the guide member, the smaller the force with which the secondary transfer unit presses the open / close cover.

  In the image forming apparatus, the secondary transfer unit includes at least a secondary transfer belt and a secondary transfer roller.

  According to the present invention, there is provided an image forming apparatus capable of preventing the opening / closing cover from being deformed without increasing the strength of the opening / closing cover itself when the unit is installed on the image forming apparatus main body side of the opening / closing cover. Is possible.

1 is a conceptual diagram illustrating a simplified overall configuration of an image forming apparatus according to an embodiment of the present invention. It is sectional drawing which shows the structure of a secondary transfer unit. It is a figure which shows simply the state by which the spindle of the spindle member is inserted in the slit of a secondary transfer unit frame, (A) is a front view, (B) is a top view. It is a figure which shows the state which closed the accumulation type opening-and-closing cover. It is a figure which shows the state which opened the accumulation type | mold opening-and-closing cover. (A) is a diagram showing the trajectory of the movement of the secondary transfer unit due to the opening operation of the accuracy type opening / closing cover, and (B) is the transition of the absolute height of the secondary transfer unit during the opening operation of the accuracy type opening / closing cover. FIG. It is a figure which shows the state which closed the fulcrum type opening / closing cover. It is a figure which shows the state which opened the fulcrum type opening / closing cover. (A) is a diagram showing a trajectory of movement of the secondary transfer unit by opening the fulcrum type opening / closing cover, and (B) is a transition of the absolute height of the secondary transfer unit when the fulcrum type opening / closing cover is opened. FIG. FIG. 4 is a diagram schematically showing a state where a part of the pressing force (transfer pressure contact load) applied to the secondary transfer unit is borne on the image forming apparatus main body side. FIG. 10 is a diagram schematically illustrating a state in which an opening / closing cover directly bears a pressing force (transfer pressing load) applied to a secondary transfer unit in a conventional image forming apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[overall structure]
FIG. 1 is a conceptual diagram showing a simplified overall configuration of an image forming apparatus 100 according to an embodiment of the present invention.

  Referring to FIG. 1, an image forming apparatus 100 according to the present embodiment forms multicolor and single color images on a predetermined sheet (recording paper) in accordance with image data transmitted from the outside. The image forming apparatus main body 110 and the automatic document processing apparatus 120 are configured.

  The image forming apparatus main body 110 includes an exposure unit 1, a developing device 2, a photosensitive drum 3, a cleaner unit 4, a charger 5, an intermediate transfer unit 6, a fixing unit 7, a paper feed cassette 81, a paper discharge tray 91, and the like. Configured.

  A document placing table 92 made of transparent glass on which a document is placed is provided on the upper portion of the image forming apparatus main body 110, and an automatic document processing device 120 is attached to the upper side of the document placing table 92.

  The automatic document processing device 120 automatically conveys the document on the document placing table 92. Further, the document processing device 120 is configured to be rotatable in the direction of arrow A, and the document can be placed manually by opening the document table 92.

  The image data handled in the image forming apparatus 100 corresponds to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y). Accordingly, four developing devices 2, photosensitive drums 3, charging devices 5, and cleaner units 4 are provided so as to form four types of latent images corresponding to the respective colors, and black, cyan, magenta, and yellow are respectively provided. These are set to form four image stations.

  The charger 5 is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential. In addition to the charger type as shown in FIG. 1, a contact type roller type or brush type charger is used. Sometimes used.

  The exposure unit 1 is composed of a laser scanning unit (LSU) provided with a laser emitting portion, a reflection mirror, and the like. The exposure unit 1 includes a polygon mirror that scans a laser beam, and optical elements such as a lens and a mirror that guide laser light reflected by the polygon mirror to the photosensitive drum 3. In addition, as the exposure unit 1, for example, a technique using an EL or LED writing head in which light emitting elements are arranged in an array can be employed. Such an exposure unit 1 has a function of forming an electrostatic latent image corresponding to the image data on the surface thereof by exposing the charged photosensitive drum 3 according to the input image data.

  The developing unit 2 visualizes the electrostatic latent images formed on the respective photosensitive drums 3 with toners of four colors (Y, M, C, K).

  The cleaner unit 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  An intermediate transfer unit 6 is disposed above the photosensitive drum 3. The intermediate transfer unit 6 includes an intermediate transfer belt 61, an intermediate transfer belt driving roller 62, an intermediate transfer belt driven roller 63, an intermediate transfer roller 64, and an intermediate transfer belt cleaning unit 65. Four intermediate transfer rollers 64 are provided corresponding to the respective colors for Y, M, C, and K.

  The intermediate transfer belt driving roller 62, the intermediate transfer belt driven roller 63, and the intermediate transfer roller 64 are driven to rotate while the intermediate transfer belt 61 is stretched. Each intermediate transfer roller 64 provides a transfer bias for transferring the toner image on the photosensitive drum 3 onto the intermediate transfer belt 61.

  The intermediate transfer belt 61 is provided in contact with each photosensitive drum 3. A function of forming a color toner image (multicolor toner image) on the intermediate transfer belt 61 by sequentially superimposing and transferring the toner images of the respective colors formed on the photosensitive drum 3 onto the intermediate transfer belt 61. have. The intermediate transfer belt 61 is formed in an endless shape using, for example, a film having a thickness of about 100 μm to 150 μm.

  The toner image is transferred from the photosensitive drum 3 to the intermediate transfer belt 61 by an intermediate transfer roller 64 that is in contact with the back side of the intermediate transfer belt 61. A high-voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 64 in order to transfer the toner image.

  The intermediate transfer roller 64 is a roller based on a shaft made of a metal (for example, stainless steel) having a diameter of 8 to 10 mm and whose surface is covered with a conductive elastic material (for example, EPDM, urethane foam, etc.). is there. With this conductive elastic material, a high voltage can be uniformly applied to the intermediate transfer belt 61. In this embodiment, a roller shape is used as the transfer electrode, but a brush or the like can also be used.

  As described above, the electrostatic images visualized on the respective photosensitive drums 3 according to the respective hues are stacked on the intermediate transfer belt 61. In this way, the laminated image information is arranged at the intermediate transfer belt 61 and the secondary transfer belt 210 of the secondary transfer unit 10 disposed at a contact position between a later-described sheet and the intermediate transfer belt 61 (see FIG. 2). Is transferred onto the paper by the rotation of. At this time, the intermediate transfer belt 61 and the secondary transfer belt 210 are pressed against each other at a predetermined nip.

  Further, as described above, the toner adhered to the intermediate transfer belt 61 by contacting the photosensitive drum 3 or the toner remaining on the intermediate transfer belt 61 without being transferred onto the sheet by the secondary transfer belt 210 The intermediate transfer belt cleaning unit 65 is configured to remove and collect the toner in order to cause toner color mixing in the next process.

  The intermediate transfer belt cleaning unit 65 is provided with a cleaning blade that is in contact with the intermediate transfer belt 61, for example, as a cleaning member. The intermediate transfer belt 61 in contact with the cleaning blade is driven by an intermediate transfer belt driven roller 63 from the back side. It is supported.

  The paper feed cassette 81 is a tray for storing sheets (recording paper) used for image formation, and is provided below the exposure unit 1 of the image forming apparatus main body 110. A sheet used for image formation can also be placed in the manual sheet feeding cassette 82. Furthermore, a paper discharge tray 91 provided above the image forming apparatus main body 110 is a tray for collecting printed sheets face down.

  Further, the image forming apparatus main body 110 has a substantially vertical sheet for feeding the sheets of the paper feed cassette 81 and the manual paper feed cassette 82 to the paper discharge tray 91 via the secondary transfer unit 10 and the fixing unit 7. A conveyance path S is provided. In the vicinity of the paper transport path S from the paper feed cassette 81 or the manual paper feed cassette 82 to the paper discharge tray 91, pickup rollers 11a and 11b, a plurality of transport rollers 12a, 12b, 12c and 12d, registration rollers 13, and secondary rollers. A transfer unit 10 and a fixing unit 7 are arranged.

  The conveyance rollers 12 a to 12 d are small rollers for promoting and assisting conveyance of the sheet, and a plurality of conveyance rollers 12 a to 12 d are provided along the sheet conveyance path S.

  The pickup roller 11 a is provided near the end of the paper feed cassette 81, picks up sheets one by one from the paper feed cassette 81, and supplies them to the paper transport path S. Similarly, the pickup roller 11 b is provided in the vicinity of the end of the manual paper feed cassette 82, picks up sheets one by one from the manual paper feed cassette 82, and supplies them to the paper transport path S.

  The registration roller 13 temporarily holds the sheet conveyed through the sheet conveyance path S, and the sheet is transferred to the secondary transfer unit 10 at the timing when the leading edge of the toner image on the photosensitive drum 3 is aligned with the leading edge of the sheet. It has a function to convey.

  The fixing unit 7 includes a heat roller 71 and a pressure roller 72, and the heat roller 71 and the pressure roller 72 rotate with the sheet interposed therebetween.

  The heat roller 71 is set by the control unit to reach a predetermined fixing temperature based on a signal from a temperature detector (not shown). The transferred multi-color toner image has a function of fusing, mixing, and press-contacting and thermally fixing the sheet. An external heating belt 73 for heating the heat roller 71 from the outside is provided.

  Next, the sheet conveyance path will be described in detail.

  As described above, the image forming apparatus 100 is provided with the paper feed cassette 81 and the manual paper feed cassette 82 for storing sheets in advance. Pickup rollers 11a and 11b are arranged to feed sheets from these sheet feeding cassettes 81 and 82, and guide the sheets one by one to the conveyance path S.

  The sheet conveyed from each of the sheet feeding cassettes 81 and 82 is conveyed to the registration roller 13 by the conveying roller 12a in the sheet conveying path S, and the timing at which the leading edge of the sheet and the leading edge of the image information on the intermediate transfer belt 61 are aligned. It is conveyed to the secondary transfer unit 10 and image information is written on the sheet. Thereafter, the sheet passes through the fixing unit 7, whereby unfixed toner on the sheet is melted and fixed by heat, and then discharged onto the paper discharge tray 91 through the transport roller 12 b disposed thereafter.

  The above-described conveyance path is for a request for single-sided printing on a sheet. On the other hand, for a request for double-sided printing, as described above, after the sheet that has finished single-sided printing and has passed through the fixing unit 7. When the end is gripped by the final transport roller 12b, the transport roller 12b rotates in the reverse direction to guide the sheet to the transport rollers 12c and 12d. Thereafter, after printing is performed on the back surface of the sheet through the registration roller 13, the sheet is discharged to the discharge tray 91.

[Configuration of Secondary Transfer Unit 10]
FIG. 2 is a cross-sectional view showing the configuration of the secondary transfer unit 10.

  Referring to FIG. 2, the secondary transfer unit 10 includes a secondary transfer roller 200, a driving roller 202, a driven roller 204, tension rollers 206 and 208, a secondary transfer belt 210, and the like.

  A voltage for transferring the toner onto the sheet is applied to the secondary transfer roller 200 (a high voltage having a polarity (+) opposite to the charging polarity (−) of the toner). In order to obtain the nip constantly, either the secondary transfer roller 200 or the intermediate transfer belt drive roller 62 is made of a hard material (metal or the like), and the other is made of a soft material such as an elastic roller (elasticity or the like). Rubber roller or foaming resin roller, etc.).

  The secondary transfer roller 200, the driving roller 202, the first tension roller 206, the driven roller 204, and the second tension roller 208 are arranged in this order clockwise with respect to the secondary transfer roller 200.

  The secondary transfer belt 210 is an endless belt and is wound around the secondary transfer roller 200, the driving roller 202, the driven roller 204, and the tension rollers 206 and 208. The roller shafts of the secondary transfer roller 200, the driving roller 202, the driven roller 204, and the tension rollers 206 and 208 are supported by a pair of left and right frames 212. In FIG. 2, only the frame on the back side is shown as the frame 212.

  The secondary transfer unit 10 is installed on the image forming apparatus main body 110 side of an opening / closing cover 214 that opens and closes an opening of the image forming apparatus main body 110. The secondary transfer unit 10 is pivotally supported so that one side (opening / closing cover 214 side) is movable with respect to the opening / closing cover 214, while the other side (intermediate transfer unit 6 side) is in a free state. It can swing.

  Specifically, a receiving member 216 for receiving the frame 212 of the secondary transfer unit 10 is fixed to the image forming apparatus main body 110 side of the opening / closing cover 214. The receiving member 216 has a box shape, and a support shaft member 218 for supporting the frame 212 of the secondary transfer unit 10 and a support shaft member 218 are attached to the intermediate transfer unit 6 side. A pressing contact spring 220 is accommodated.

  The support shaft member 218 includes a support member main body 222 that slides within the receiving member 216, and a support shaft 224 that protrudes from the side surface of the support member main body 222 toward the frame 212 of the secondary transfer unit 10. Has been. The support shaft member main body 222 and the support shaft 224 are integrally provided.

  The pressure contact spring 220 is a spring for pressing the secondary transfer belt 210 of the secondary transfer unit 10 against the intermediate transfer belt 61 of the intermediate transfer unit 6, and is formed between the support member main body 222 and the rear wall of the receiving member 216. Intervened in between. That is, one end portion of the pressure contact spring 220 is attached to the rear wall of the receiving member 216, and the other end portion is attached to the rear wall of the support member main body 222.

  On the other hand, a slit 226 is formed on one side (opening / closing cover 214 side) of the frame 212 of the secondary transfer unit 10. The slit 226 has a shape bent toward the opening / closing cover 214 side, and the support shaft 224 of the support shaft member 218 is inserted therein.

  As shown in FIG. 3, the support shaft 224 provided integrally with the support member main body 222 that can move with respect to the opening / closing cover 214 as the secondary transfer unit 10 swings is provided as the secondary transfer unit 10. It moves in the slit 226 of the transfer unit frame 212. That is, the secondary transfer unit 10 is supported to be swingable with respect to the opening / closing cover 214 by the support shaft 224 moving in the slit 226.

  Referring to FIG. 2 again, a guide shaft 228 protrudes from the frame 212 of the secondary transfer unit 10 on the other end side (the side opposite to the area where the slit 226 is formed). The guide shaft 228 is disposed substantially coaxially with the roller shaft of the driven roller 204. In contrast, the image forming apparatus main body 110 includes a guide member 230 that guides the secondary transfer unit 10 when the opening / closing cover 214 is closed. The guide member 230 is provided with a notch 232 at a position where the guide shaft 228 is introduced so as to extend the movement locus of the secondary transfer unit 10 when the opening / closing cover 214 is closed. Thereby, when the opening / closing cover 214 is closed, the guide shaft 228 of the secondary transfer unit 10 enters the notch 232 of the guide member 230.

  In the present embodiment, the opening direction P1 of the notch 232 of the guide member 230 is orthogonal to the direction P2 of the pressing force received by the secondary transfer unit 10.

  Further, the frame 212 of the secondary transfer unit 10 is provided with a positioning member 234 at the edge portion on the secondary transfer roller 200 side. On the other hand, the image forming apparatus main body 110 is provided with a positioning boss 236 above the vicinity of the transfer nip between the intermediate transfer belt 61 and the secondary transfer belt 210. The positioning member 234 has a notch 238 that opens toward the positioning boss 236. Accordingly, when the guide shaft 228 of the secondary transfer unit 10 enters the notch 232 of the guide member 230 in accordance with the closing operation of the opening / closing cover 214, the notch 238 of the positioning member 234 on the secondary transfer unit 10 side is imaged. The secondary transfer unit 10 is positioned at a required position by engaging with the positioning boss 236 on the forming apparatus main body 110 side.

  That is, in the present embodiment, when the open / close cover 214 is closed, the secondary transfer unit 10 is positioned above the transfer nip between the secondary transfer unit 10 and the intermediate transfer unit 6, and below the transfer nip. Thus, the secondary transfer unit 10 is supported by the guide member 230.

  Further, in this embodiment, the distance between the transfer nip and the point where the secondary transfer unit 10 is supported by the guide member 230 is the point where the transfer nip and the secondary transfer unit 10 are held by the opening / closing cover 214. It is set longer than the distance.

[Operation]
As shown in FIGS. 4 and 5, the opening / closing cover 214 includes an accumulator-type opening / closing cover (part 1) that can move linearly in the horizontal direction with respect to the image forming apparatus main body 110, and FIGS. 7 and 8. As shown in FIG. 2, there is a fulcrum type opening / closing cover (part 2) that is rotatable about the fulcrum 300 with respect to the image forming apparatus main body 110.

<Operation at Opening Operation of Opening / Closing Cover 214>
(Part 1)
FIG. 6A is a diagram showing a trajectory of the movement of the secondary transfer unit 10 by the opening operation of the accuracy type opening / closing cover 214, and FIG. 6B is a secondary transfer at the time of opening operation of the accuracy type opening / closing cover 214. It is a figure which shows transition of the absolute height of the unit. Here, “the absolute height of the secondary transfer unit 10” refers to the height from the installation surface of the image forming apparatus 100 to the secondary transfer unit 10.

  With reference to FIG. 6A, at the closed position L0 of the accumulator opening / closing cover 214, the guide shaft 228 of the secondary transfer unit 10 enters the notch 232 of the guide member 230 and the secondary transfer unit 10 The notch 238 of the positioning member 234 is engaged with the positioning boss 236.

  When the open / close cover 214 is moved horizontally in this direction from the above state, the secondary transfer unit 10 rotates clockwise around the guide shaft 228 until the cover open position L2 (for example, 5 mm) is reached. When the cover open position reaches L2, the notch 238 of the positioning member 234 of the secondary transfer unit 10 is detached from the positioning boss 236. Meanwhile, as shown in FIG. 6B, the absolute height of the secondary transfer unit 10 gradually decreases from H0 → H1 (<H0) → H2 (<H1) with H0 as the highest point.

  6A, from the cover open position L2 where the notch 238 of the positioning member 234 of the secondary transfer unit 10 is removed from the positioning boss 236, the open / close cover 214 is further moved horizontally in the open direction to When the cover opening position reaches L3 (for example, 10 mm), the support shaft 224 of the support shaft member 218 moves to the upper part of the slit 226 of the secondary transfer unit 10. During this time, the absolute height of the secondary transfer unit 10 gradually decreases from H2 to H3 (<H2) as shown in FIG. 6B. When the opening position L3 of the opening / closing cover 214 is exceeded, the guide shaft 228 of the secondary transfer unit 10 is detached from the notch 232 of the guide member 230 when this is triggered.

  6A, when the opening / closing cover 214 is further moved horizontally in the opening direction until the cover opening position changes from L3 to L4 (for example, 15 mm), the guide shaft 228 of the secondary transfer unit 10 is moved. The guide member 230 is completely removed. During this time, the absolute height of the secondary transfer unit 10 gradually increases from H3 to H4 (> H3) with H3 as the lowest point, as shown in FIG. 6B.

  6A, from the cover opening position L4 where the guide shaft 228 of the secondary transfer unit 10 is completely removed from the guide member 230, the opening / closing cover 214 is further moved horizontally in the opening direction to When the cover open position reaches L5 (for example, 20 mm), the secondary transfer unit 10 moves horizontally following the movement track of the opening / closing cover 214 during this period. That is, after the guide shaft 228 of the secondary transfer unit 10 is completely removed from the guide member 230 at the cover open position L4, the absolute height of the secondary transfer unit 10 is changed to H4.

(Part 2)
FIG. 9A is a diagram showing a locus of movement of the secondary transfer unit 10 by opening the fulcrum type opening / closing cover 214, and FIG. 9B is a secondary transfer when the fulcrum type opening / closing cover 214 is opened. It is a figure which shows transition of the absolute height of the unit.

  Referring to FIG. 9A, in the closed state α0 of the fulcrum type opening / closing cover 214, the guide shaft 228 of the secondary transfer unit 10 enters the notch 232 of the guide member 230 and the secondary transfer unit 10 The notch 238 of the positioning member 234 is engaged with the positioning boss 236.

  When the opening / closing cover 214 is rotated about the fulcrum 300 in the opening direction from this state, the secondary transfer unit 10 rotates clockwise about the guide shaft 228 until the cover opening angle α3 (for example, 5 degrees). When the opening angle of the opening / closing cover 214 reaches α3, the notch 238 of the positioning member 234 of the secondary transfer unit 10 is detached from the positioning boss 236. During this period, as shown in FIG. 9B, the absolute height of the secondary transfer unit 10 gradually decreases from H0 to H1 (<H0) → H2 (<H1) → H3 (<H2) with H0 as the highest point. Become.

  Referring to FIG. 9A, the opening / closing cover 214 is further rotated about the fulcrum 300 in the opening direction from the cover opening angle α3 at which the notch 238 of the positioning member 234 of the secondary transfer unit 10 is detached from the positioning boss 236. When the open position of the opening / closing cover 214 reaches α4 (for example, 10 degrees), the support shaft 224 of the support shaft member 218 moves to the upper part of the slit 226 of the secondary transfer unit 10 and the guide shaft 228 of the secondary transfer unit 10. Comes out of the notch 232 of the guide member 230. During this time, the absolute height of the secondary transfer unit 10 gradually increases from H3 to H4 (> H3) with H3 as the lowest point, as shown in FIG. 9B. When the cover opening angle α4 of the opening / closing cover 214 is exceeded, the guide shaft 228 of the secondary transfer unit 10 is completely detached from the guide member 230 when this is triggered.

  Referring to FIG. 9A, when the opening / closing cover 214 is further rotated in the opening direction about the fulcrum 300 and the cover opening angle of the opening / closing cover 214 reaches α5 (for example, 20 degrees), the secondary movement is performed during this period. The transfer unit 10 moves following the movement path of the opening / closing cover 214. That is, after the guide shaft 228 of the secondary transfer unit 10 is completely detached from the guide member 230, the absolute height of the secondary transfer unit 10 is H4 → H5 (> H4) as shown in FIG. 9B. And higher.

<Operation when opening / closing cover 214 is closed>
When the two types of opening / closing covers 214 are closed, the guide shaft 228 of the secondary transfer unit 10 enters the notch 232 of the guide member 230 as shown in FIG. At this time, the notch 238 of the positioning member 234 of the secondary transfer unit 10 is engaged with the positioning boss 236. As a result, in the image forming apparatus main body 110, the secondary transfer unit 10 is positioned above the transfer nip between the secondary transfer unit 10 and the intermediate transfer unit 6, and the secondary transfer unit 10 is positioned below the transfer nip. It will be supported by the guide member 230.

[Action / Effect]
According to the present embodiment, the following operations and effects are achieved.

  (1) When the opening / closing cover 214 is closed, at least a part of the pressing force (transfer pressure contact load) applied to the secondary transfer unit 10 can be borne on the image forming apparatus main body 110 side. Therefore, when the secondary transfer unit 10 is installed on the image forming apparatus main body 110 side of the opening / closing cover 214, it is possible to prevent the opening / closing cover 214 from being deformed without increasing the strength of the opening / closing cover 214 itself. Specifically, when the opening / closing cover 214 is closed, the guide shaft 228 of the secondary transfer unit 10 enters the notch 232 of the guide member 230 on the image forming apparatus main body 110 side. Therefore, at least a part of the pressing force applied to the secondary transfer unit 10 can be borne reliably on the image forming apparatus main body 110 side. That is, the transfer pressure contact load from the intermediate transfer unit 6 is not applied to the open / close cover 214 as it is from the secondary transfer unit 10 installed on the image forming apparatus main body 110 side of the open / close cover 214. There is no possibility that the opening / closing cover 214 is deformed. For example, as shown in FIG. 10, if the pressing force (transfer pressure contact load) applied to the secondary transfer unit 10 is 6 kg, as shown in FIG. 10, the secondary transfer unit 10 is placed on the image forming apparatus main body 110 side. A load of 3 kg is applied to the opening / closing cover 214 (not shown in FIG. 10) on which is installed, and a load of 3 kg is applied to the guide member 230 on the image forming apparatus main body 100 side.

  (2) Since the opening direction P1 of the notch 232 of the guide member 230 is orthogonal to the direction P2 of the pressing force received by the secondary transfer unit 10, the guide of the secondary transfer unit 10 when the opening / closing cover 214 is closed. The shaft 228 does not come off the guide member 230. Therefore, a part of the pressing force received by the secondary transfer unit 10 can be borne efficiently on the image forming apparatus main body 110 side. Further, no loss occurs in the closing speed of the opening / closing cover 214.

  (3) Since the secondary transfer unit 10 is held so as to be swingable with respect to the opening / closing cover, the guide shaft 228 of the secondary transfer unit 10 easily enters the notch 232 of the guide member 230.

  (4) When the open / close cover 214 is closed, the secondary transfer unit 10 is positioned above the transfer nip, and the secondary transfer unit 10 is supported by the guide member 230 below the transfer nip. The load capacity for the pressing force applied to the secondary transfer unit 10 on the main body 110 side is increased.

  (5) The distance between the transfer nip and the point where the secondary transfer unit 10 is supported by the guide member 230 is set longer than the distance between the transfer nip and the point where the secondary transfer unit 10 is held by the opening / closing cover 214. However, as the distance between the transfer nip and the point where the secondary transfer unit 10 is supported by the guide member 230 is longer, the force with which the secondary transfer unit 10 presses the opening / closing cover 214 can be reduced.

  The present invention is not limited to the above embodiment.

  For example, in the above embodiment, an example in which the secondary transfer unit is installed on the image forming apparatus main body side of the opening / closing cover is described. However, the present invention is not limited to such a configuration. A unit installed on the image forming apparatus main body side of the opening / closing cover may be a relay unit that relays the sheet to the transfer nip.

  In the above embodiment, an example in which the opening direction of the notch of the guide member is orthogonal to the direction in which the pressing force applied to the secondary transfer unit is described. However, the present invention is not limited to such a configuration. The opening direction of the notch of the guide member only needs to intersect the direction of action of the pressing force applied to the secondary transfer unit.

  It goes without saying that various design changes and modifications can be made within the scope of the claims attached to this specification.

  That is, the embodiment disclosed in this specification is merely an example, and the present specification is not limited to the embodiment described above. The scope of the present invention is indicated by the appended claims after taking into account the description of the present specification, and includes all modifications within the meaning and scope equivalent to the words described therein.

3 Photosensitive drum 6 Intermediate transfer unit 7 Fixing unit 10 Secondary transfer unit (corresponding to the unit described in claims)
100 Image forming apparatus 110 Image forming apparatus main body 200 Secondary transfer roller 210 Secondary transfer belt 214 Open / close cover 228 Guide shaft 230 Guide member 232 Notch

Claims (10)

An opening / closing cover that is movably supported with respect to the image forming apparatus main body, and that opens and closes an opening of the image forming apparatus main body;
An image forming apparatus comprising a unit swingably installed on the image forming apparatus main body side of the opening and closing cover,
An image forming apparatus comprising: a pressing force bearing unit configured to load at least a part of the pressing force applied to the unit on the image forming apparatus main body side when the opening / closing cover is closed. The image forming apparatus according to claim 1.
The pressing force bearing means is provided in the image forming apparatus main body, a guide member in which a notch is formed on an extension of a movement locus of the unit when the opening / closing cover is closed, and a guide provided in the unit. Including an axis,
The image forming apparatus according to claim 1, wherein when the opening / closing cover is closed, the guide shaft of the unit enters the notch of the guide member. The image forming apparatus according to claim 2.
2. An image forming apparatus according to claim 1, wherein the opening direction of the notch of the guide member intersects the direction of the pressing force received by the unit. The image forming apparatus according to any one of claims 1 to 3,
2. The image forming apparatus according to claim 1, wherein the unit is swingable by being pivotally supported on one side with respect to the opening / closing cover and free on the other side. The image forming apparatus according to any one of claims 1 to 4,
The image forming apparatus, wherein the opening / closing cover is linearly movable in a horizontal direction with respect to the image forming apparatus main body. The image forming apparatus according to any one of claims 1 to 4,
The image forming apparatus, wherein the opening / closing cover is rotatable about a fulcrum with respect to the image forming apparatus main body. The image forming apparatus according to any one of claims 1 to 6,
The unit is a secondary transfer unit;
An image forming apparatus comprising: an image carrier; and an intermediate transfer unit that transfers a toner image on the surface of the image carrier to a sheet. The image forming apparatus according to claim 7.
When the opening / closing cover is closed, the secondary transfer unit is positioned above the transfer nip between the secondary transfer unit and the intermediate transfer unit, and the secondary transfer unit is positioned below the transfer nip. An image forming apparatus supported by a member. The image forming apparatus according to claim 8.
The distance between the transfer nip and the point where the secondary transfer unit is supported by the guide member is longer than the distance between the transfer nip and the point where the secondary transfer unit is held by the opening / closing cover. An image forming apparatus. The image forming apparatus according to any one of claims 7 to 9,
The image forming apparatus, wherein the secondary transfer unit includes at least a secondary transfer belt and a secondary transfer roller.

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