1. Field of the Invention
The present invention relates to a belt device for use in an image forming apparatus.
2. Description of the Related Art
Tandem color image forming apparatuses, such as copiers and printers, including an intermediate transfer belt (belt device) are well-known in the art. Such image forming apparatuses have been disclosed in, for example, Japanese Patent Application Laid-open No. 2004-341087 and Japanese Patent No. 3473148.
In a typical image forming apparatus, four photosensitive drums (image carriers) are provided side by side facing an intermediate transfer belt (belt member). Single-color toner images for black, yellow, magenta, and cyan are respectively formed on each of the four photosensitive drums. Those single-color toner images are then transferred so as to be overlaid on top of each other on the intermediate transfer belt to form a color toner image on the intermediate transfer belt. The color toner image supported on the intermediate transfer belt is then transferred to and fixed on a recording medium, such as a paper, as a color image.
Configurations where an intermediate transfer belt device can be pulled out to the front with respect to an image forming apparatus body are common. Such a configuration makes maintenance of the intermediate transfer belt device straightforward. Specifically, in Japanese Patent Application Laid-open No. 2004-341087, a transfer module fitted with an intermediate transfer belt is mounted on an intermediate transfer belt device. After then pulling the intermediate transfer belt device (transfer unit) to the front with respect to the image forming apparatus body, the transfer module mounted on the intermediate transfer belt device can be detached from above.
With the image forming apparatus of Japanese Patent Application Laid-open No. 2004-341087, it is necessary for the transfer module mounted on the intermediate transfer belt apparatus to be detached upwards after the intermediate transfer belt device (belt device) is pulled out to the front with respect to the image forming apparatus body while changing the intermediate transfer belt (belt member). However, in this configuration, ease of maintenance (maintenance operativity) of the intermediate transfer belt device, such as changing of the intermediate transfer belt, drops.
In order to resolve this situation, it is therefore preferable to ensure that maintenance of the intermediate transfer belt device is possible in a state where the intermediate transfer belt device is pulled out to the front with respect to the image forming apparatus body. This can, however, cause a frame of the intermediate transfer belt device to deform as a result of the intermediate transfer belt device being pulled out with respect to the image forming apparatus body for a long period of time. Deformation of the frame of the intermediate transfer belt device can lead to misalignment of various components mounted on the frame and can cause degradation of image quality. This problem is particularly difficult to ignore in large image forming apparatus where the weight of the intermediate transfer belt apparatus is substantial. The outer periphery of the intermediate transfer belt of conventional apparatus is substantially covered by a frame. It is therefore not possible to change the intermediate transfer belt with a single action in a state where the intermediate transfer belt device is pulled out to the front with respect to the image forming apparatus body.
It is an object of the present invention to at least partially solve the problems in the conventional technology.
According to an aspect of the present invention, there is provided a belt device for use in an image forming apparatus such that the belt device can be pulled out to the front with respect to a body of the image forming apparatus. The belt device includes an endless belt member supported at a plurality of roller members so as to travel in a predetermined direction; two side frames disposed along sides of the belt member in the direction of travel of the belt member, the side frames being respectively slidably supported at two slide rails disposed at the body; a rear frame constructed to the rear across the two side frames, rotatably supporting shafts of the roller members at the rear side, and having a box-type structure; a front frame rotatably supporting shafts of the roller members on the front side, and having a projecting surface smaller than an inner periphery of the belt member when viewed from the front; a support frame cantilever-supporting the front frame with respect to the rear frame; and triangular reinforcing members constructed across both the side frames and the rear frame near joints of the side frames and the rear frame.
According to another aspect of the present invention, there is provided a belt device for use in an image forming apparatus such that the belt device can be pulled out to the front with respect to a body of the image forming apparatus. The belt device includes an endless belt member supported at a plurality of roller members so as to travel in a predetermined direction; a plurality of side frames disposed along sides of the belt member in the direction of travel of the belt member, the side frames being respectively slidably supported at a plurality of slide rails disposed at the body; a rear frame constructed across the side frames, rotatably supporting shafts of the roller members at the rear side; a front frame rotatably supporting the shafts of the roller members at the front side, and having a projecting surface smaller than an inner periphery of the belt member when viewed from a pulling out direction; and a support frame cantilever-supporting the front frame with respect to the rear frame.
According to still another aspect of the present invention, there is provided a belt device for use in an image forming apparatus such that the belt device can be pulled out to the front with respect to a body of the image forming apparatus. The belt device includes an endless belt member supported at a plurality of roller members so as to travel in a predetermined direction; a rear frame comprising a freely detachable holding member supporting rear side bearings that support the rear side shafts of the roller members in a freely rotatable manner, and a sub-bearing having a larger internal diameter than an outer diameter of the rear side shaft section of the roller member more to a center side in an axial direction than a position of the rear side bearing; and a front frame comprising front-side bearings supporting the front side shafts of the roller member in a freely rotatable manner.
The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.
Exemplary embodiments of the present invention are explained in detail in the following with reference to the drawings. Corresponding or identical portions in the drawings are given the same numerals, with duplicate explanations being simplified or omitted as appropriate.
In this application, “to the front” is defined as the side to which the belt device is pulled outwards with respect to the image forming apparatus body (side to the front side of the pulling out direction). Further, “to the rear” is the opposite side to “to the front” and is defined as a direction of pulling out the belt device to the back. “Widthwise direction” is defined as a horizontal direction orthogonal to the pulling-out direction.
A first embodiment of the present invention is explained in detail below with reference to
First, an overall structure and operation of an image forming apparatus is explained with reference to
As shown in
With the exception of the color of the toner used being different, the remaining three operation units 6M, 6C, 6K have substantially the same structure as the operation unit 6Y for yellow and form images corresponding to the respective toner colors. In the following, a description is given only of the operation unit 6Y, with descriptions of the remaining three operation units 6M, 6C, 6K being omitted as appropriate.
Referring to
The latent-image formed surface of the photosensitive drum 1Y then reaches a position corresponding to the developing unit 5Y. A latent image is developed at this position and a yellow toner image is formed (developing). The toner-image formed surface of the photosensitive drum 1Y then reaches a position corresponding to the intermediate transfer belt 8 (belt member) and the transfer roller 9Y (primary transfer roller). A toner image on the photosensitive drum 1Y is then transferred onto the intermediate transfer belt 8 at this position (primary transfer). A small amount of un-transferred toner may remain on the photosensitive drum 1Y at this time.
The surface of the photosensitive drum 1Y then reaches a position corresponding to the cleaning unit 2Y. Un-transferred toner remaining on the photosensitive drum 1Y at this position is then recovered to within the cleaning unit 2Y by a cleaning blade 2a (cleaning). Finally, the surface of the photosensitive drum 1Y reaches a position corresponding to the charge removal unit (not shown). Residual potential on the photosensitive drum 1Y is then completely removed at this position. This completes a series of development processes carried out on the photosensitive drum 1Y.
The development processes for the operation units 6M, 6C, 6K are the same as for the yellow operation unit 6Y. Laser light L based on image information is irradiated from the light exposure unit 7 disposed above the operation unit towards photosensitive drums 1M, 1C, 1K of each operation unit 6M, 6C, 6K. The light exposure unit 7 emits the laser light L from a light source and irradiates the photosensitive drum with the laser light L via a plurality of optical elements while scanning with the laser light using a rotating polygon mirror. Toner images for each color formed on each photosensitive drum via the developing step are then overlaid and transferred onto the intermediate transfer belt 8 thereby forming a full color image on the intermediate transfer belt 8.
As shown in
The four transfer rollers 9Y, 9M, 9C, and 9K (primary transfer rollers) form a primary transfer nip by sandwiching the intermediate transfer belt 8 together with the photosensitive drums 1Y, 1M, 1C, and 1K. A transfer voltage (transfer bias) of a polarity opposite to the toner polarity is then applied to the transfer rollers 9Y, 9M, 9C, and 9K. The intermediate transfer belt 8 then travels in the clockwise direction and sequentially passes through the primary transfer nip of the transfer rollers 9Y, 9M, 9C, and 9K. Toner images for each of the colors on the photosensitive drums 1Y, 1M, 1C, and 1K then undergo primary transfer so as to be overlaid on the intermediate transfer belt 8.
After this, the toner images on the intermediate transfer belt 8 reach a position facing the secondary transfer roller 19. At this position, the tension roller 12B sandwiches the intermediate transfer belt 8 together with the secondary transfer roller 19 so as to form a secondary transfer nip. A transfer voltage (secondary transfer bias) of a polarity opposite to the toner polarity is then applied to the secondary transfer roller 19. As a result, the toner images on the intermediate transfer belt 8 are transferred onto a recording medium P such as transfer paper conveyed to the position of the secondary transfer nip. At this time, un-transferred toner that was not transferred to the recording medium P may remain on the intermediate transfer belt 8.
After this, the intermediate transfer belt 8 reaches the position of the intermediate transfer cleaning unit 10. Un-transferred toner on the intermediate transfer belt 8 is then removed at this position. This completes the series of transfer processes taking place on the intermediate transfer belt 8. The structure and operation of the intermediate transfer belt device 15 taken as a belt device are now explained in detail using
Referring to
The recording medium P conveyed to the registration rollers 28 is then temporarily stopped at the position of a roller nip of the registration rollers 28 for which rotation has stopped. The registration rollers 28 are then rotated in line with the timing of a color image on the intermediate transfer belt 8 and the recording medium P is conveyed in the direction of the secondary transfer nip. An image of the desired color is therefore transferred onto the recording medium P.
After this, the recording medium P to which the color image is transferred to at the position of the secondary transfer nip is conveyed to the position of a fixing unit 20. In the fixing unit 20 the color image transferred to the surface is fixed onto the recording medium P using heat and pressure of a fixing roller and a pressure roller. The recording medium P is then discharged to outside of the device by a pair of paper ejection rollers (not shown). The recording media P subjected to transfer is discharged to outside of the device by the paper ejection rollers is then sequentially stacked on a stack unit as output images. The series of image-forming processes occurring at the image forming apparatus body 100 are then complete.
Next, a detailed description is given of the structure and operation of the developing unit 5Y. The developing unit 5Y includes a developing roller 51Y facing the photosensitive drum 1Y, a doctor blade 52Y facing the developing roller 51Y, two conveyor screws 55Y disposed within a developer container, a toner supply path 43Y communicating via an opening at the developer container, and a density detection sensor 56 that detects toner density within the developer. The developing roller 51Y includes a magnet installed inside and a sleeve rotating the periphery of the magnet. A two-component developer composed of a carrier and a toner is housed within the developer container.
The developing unit 5Y operates as follows. The sleeve of the developing roller 51Y rotates in the direction of the arrow of
The developer supported on the developing roller 51Y is conveyed in the direction of the arrow of
Next, the intermediate transfer belt device 15 (belt device) of this embodiment is explained referring to
Referring to
The intermediate transfer belt 8 taken as a belt member is disposed facing the photosensitive drums 1Y, 1M, 1C, and 1K taken as four image carriers supporting toner images for each color. The intermediate transfer belt 8 is supported in a tensioned manner mainly on five roller members, i.e., the drive roller 12A, the tension roller 12B, the tension roller 12C, the correction roller 13, and the restricting roller 14.
The intermediate transfer belt 8 can be formed from one or a plurality of layers of PVDF (polyvinylidene fluoride), ETFE (ethylene tetrafluoroethylene), PI (polyamide), or PC (polycarbonate) etc. dispersed in a conductive material such as carbon black. The intermediate transfer belt 8 is adjusted to have a volume resistivity of 107 ohm/cm to 1012 ohm/cm, and the surface resistivity of the rear surface side of the belt is adjusted to the range of 108 ohm/cm to 1012 ohm/cm. The intermediate transfer belt 8 can have a thickness in the range of 80 micrometers to 100 micrometers. In this embodiment, a 90-micrometer thick and 2197.5-millimeter long intermediate transfer belt 8 was used. The surface of the intermediate transfer belt 8 can be coated with a separating layer as necessary. During this time, a fluororesin such as ETFE (ethylene tetrafluoroethylene), PTFE (polytetrafluoroethylene), PVDF (polyvinylidene fluoride), PEA (perfluoroalkoxy), FEP (fluorinated ethyl propylene copolymer), or PVF (polyvinyl fluoride) is used but this is not limiting. The method for manufacturing the intermediate transfer belt 8 can be an injection method or a centrifugal forming method etc. with the surface being polished as necessary.
The transfer rollers 9Y, 9M, 9C, and 9K face the corresponding photosensitive drums 1Y, 1M, 1C, and 1K with the intermediate transfer belt 8 therebetween. Specifically, the yellow transfer roller 9Y faces the yellow photosensitive drum 1Y with the intermediate transfer belt 8 therebetween, the magenta transfer roller 9M faces the magenta photosensitive drum 1M with the intermediate transfer belt 8 therebetween, the cyan transfer roller 9C faces the cyan photosensitive drum 1C with the intermediate transfer belt 8 therebetween, and the black transfer roller 9K faces the photosensitive drum 1C with the intermediate transfer belt 8 therebetween.
The four transfer rollers 9Y, 9M, 9C, and 9K are configured so that they can separate the intermediate transfer belt 8 from the photosensitive drums 1Y, 1M, 1C, and 1K. Specifically, the three transfer rollers 9Y, 9M, and 9C for color use out of the four transfer rollers 9Y, 9M, 9C, and 9K are integrally supported at a holding member (not shown) and are capable of being moved integrally in a vertical direction. The black transfer roller 9K can also be independently moved vertically. As shown in
In the first embodiment, when a color-image formation mode (a mode for forming a color image) is selected, by a contact/noncontact structure, an intermediate transfer belt 8 is made to came in contact with all of the four photosensitive drums 1Y, 1M, 1C, and 1K (the state shown in
The drive roller 12A is rotated by a drive motor 70. This causes the intermediate transfer belt 8 to advance a predetermined extent in the direction of travel (clockwise direction of
The meandering detecting unit 80 detects displacement of the intermediate transfer belt 8 in a widthwise direction (direction perpendicular to the paper of
The reciprocating member 82 includes a first arm section 82a, a rotating support shaft 82b, and a second arm section 82c. An end of the first arm section 82a abuts with the side of the intermediate transfer belt 8 and the other end is fixed to the rotating support shaft 82b. The rotating support shaft 82b is supported in a freely rotating manner at a casing (not shown) of the intermediate transfer belt device 15. An end of the second arm section 82c is fixed to the rotating support shaft 82b. An end of the spring 83 is connected to the center of the second arm section 82c. The other end of the spring 83 is connected to the casing. The reciprocating member 82 reciprocates (reciprocation in the direction of the double-headed arrow in
The distance sensor 81 is installed at the upper part of the other end of the second arm section 82c. The distance sensor 81 mainly includes light-emitting elements (infra-red light-emitting diodes) disposed next to each other spaced across the horizontal direction and a position sensing detector (PSD). Infra-red light emitted from the light-emitting elements is reflected by the surface of the second arm section 82c so as to be incident to the position detecting elements as reflected light. A position of incidence of the reflected light incident to the position detecting elements changes with a change in the distance between the distance sensor 81 and the second arm section 82c. An output value of the distance sensor 81 then changes in proportion to this. It is therefore possible to detect an extent of displacement, i.e., the distance to the surface of the second arm section 82c, of the intermediate transfer belt 8 in a widthwise direction. When a distance detected by the distance sensor 81 is larger than a predetermined value, i.e., when the output value (voltage) of the distance sensor 81 is larger than a predetermined value, it means that the intermediate transfer belt 8 is displaced in the plus direction (position shift to the left side of
In the first embodiment, the meandering detecting unit 80 detects (abnormal detection) abnormal belt bias during normal image-forming (during printing) etc. Belt position shift correction is then performed by the correction roller 13 based on the detection results of the meandering detecting unit 80 taking a belt bias (position shift) of plus or minus 0.5 millimeters (mm) with respect to a reference position (i.e., when the position shift is 0 mm) as a permitted range (permitted print range). When the belt bias (position shift) of the intermediate transfer belt 8 goes outside a detection range (plus or minus 1 mm) of the meandering detecting unit 80, it means that a comparatively large belt bias has occurred. In that case the device is therefore forcibly stopped and an abnormality detection is displayed at a display unit (not shown) of the image forming apparatus body 100. Abnormality detection is also performed by the abnormality detecting unit 88 in addition to the abnormality detection performed by the meandering detecting unit 80. This duplication of the detection of abnormalities for belt bias is carried out so that abnormality detection is reliably carried out even if the meandering detecting unit 80 is damaged or runaway of the control software occurs.
The restricting roller 14 restricts the displacement of the intermediate transfer belt 8 in a direction perpendicular to the surface of the intermediate transfer belt 8. The restricting roller 14 is disposed near to the meandering detecting unit 80. Specifically, the restricting roller 14 is near and on an upstream side in the direction of travel of the intermediate transfer belt 8 with respect to the abutting position of the first arm section 82a and the intermediate transfer belt 8. With the above structure, displacement (runout) of the intermediate transfer belt 8 in a direction perpendicular to surface of the intermediate transfer belt 8 near the meandering detecting unit 80 is alleviated. Namely, because the restricting roller 14 restricts displacement of the intermediate transfer belt 8 by applying tension to the intermediate transfer belt 8, displacement of the reciprocating member 82 in a direction perpendicular to the surface of the intermediate transfer belt 8 is also restricted. As a result, the inconvenience of detecting a displacement component for different directions to the widthwise direction and the direction of travel can be reduced. Namely, the detection precision can be improved.
If the meandering detecting unit 80 detects displacement of the intermediate transfer belt 8, the correction roller 13 (meandering correction mechanism) is used to correct the displacement. Referring to
Referring to
The arm member 90 includes a first arm section 90a, the rotating spindle 90b, and a second arm section 90c. One end of the first arm section 90a is set at a position 5 millimeters from the side of the intermediate transfer belt 8 that is in a normal position and the other end is fixed to at the rotating spindle 90b. The rotating spindle 90b is supported in a freely rotating manner at a casing (not shown) of the intermediate transfer belt device 15. An end of the second arm section 90c is fixed to the rotating spindle 90b, and the other end is set between a light-emitting unit 89a and a light-receiving unit 89b of the over-run detection sensor 89. An end of the spring 91 is connected to the center of the second arm section 90c. The other end of the spring 91 is connected to the casing. One end of the second arm section 90c abuts with a positioning section of the casing as a result of the urging force of the spring 91.
When a substantial belt bias exceeding 5 mm occurs at the intermediate transfer belt 8, the arm member 90 abuts with the intermediate transfer belt 8 and reciprocates (reciprocates in the direction of a solid line arrow in
Referring to
In the following, a feature of a first embodiment is described for a configuration for a frame for an intermediate transfer belt device 15 and a maintenance method for changing etc. of the intermediate transfer belt 8 with reference to
As shown in
Referring to
The two side frames 130 are supported at the slide rails 150 arranged on the outside of the intermediate transfer belt device 15. The rear frame 110 is fixed to the slide rails 150 via the side frames 130.
The rear frame 110 is constructed to the rear (upper part of
The front frame 115 is fixed to the rear frame 110 via the support frame 120. The front frame 115 rotatably supports the shafts (front side shafts) of the plurality of roller members 12A to 12C, 13, 14 via bearings. Shafts at the ends of the plurality of roller members 12A to 12C, 13, and 14 are rotatably supported by the rear frame 110 and the front frame 115 via bearings. The front frame 115 has a smaller projecting surface than the inner periphery (inner periphery of the intermediate transfer belt 8 with the belt tension released) of the intermediate transfer belt 8 when viewed from the front (in a pulling out direction at the lower part of
The three support frames 120 are arranged so as to provide cantilever support for the front frame 115 with respect to the rear frame 110. One of the support frames 120 (referring to
The reinforcing frames 125 taken as reinforcing members are constructed across both the frames 110 and 130 near joints of the side frames 130 and the rear frame 110. The resistance to torsion of the rear frame 110 cross-linking the two side frames 130 is therefore increased and the strength of connecting both the frames 110 and 130 is increased. The reinforcing frames 125 (reinforcing members) are substantially triangular in shape. The reinforcing frames 125 therefore function effectively as reinforcing members without space near the joints of the side frames 130 and the rear frame 110 becoming narrow. In the first embodiment, the reinforcing frame 125 is arranged with a clearance of 20 millimeters or more in the vertical direction (direction at right-angles to the paper surface of
In the first embodiment, fixing plates 160 are provided as fixing members for fixing the front frame 115 to the image forming apparatus body 100 with the intermediate transfer belt device 15 housed in the image forming apparatus body 100 (the situation in
The intermediate transfer belt 8 can be pulled out to the front from the intermediate transfer belt device 15 using the following procedure. First, the fixing plates (fixing members) 160 are removed from the image forming apparatus body 100 by the operator. The intermediate transfer belt device 15 is then pulled out (moved in the direction of the white arrow of
Referring to
When the intermediate transfer belt device 15 is pulled out from the state in
In the state in
In the first embodiment, as shown in
In the first embodiment, the front frame 115 having a projecting surface smaller than the inner periphery of the intermediate transfer belt 8 (belt member) as viewed from the front is cantilever-supported with respect to the rear frame 110. Mechanical strength with respect to force applied to the intermediate transfer belt device 15 (belt device) when the image forming apparatus body 100 is pulled out is therefore effectively increased. It is therefore possible to improve ease of maintenance of the intermediate transfer belt device 15 including changing of the intermediate transfer belt 8 without deformation of the intermediate transfer belt device 15.
A second embodiment of the present invention is now explained in detail using
The intermediate transfer belt device 15 of the second embodiment also includes the intermediate transfer belt 8, the four transfer rollers 9Y, 9M, 9C, and 9K, the drive roller 12A, the tension rollers 12B and 12C, the correction roller 13, the restricting roller 14, the meandering detecting unit 80, the abnormality detecting unit 88, a photosensor 901, and the intermediate transfer cleaning unit 10, etc. (see
Referring to
Referring to
Normally (when the intermediate transfer belt device 15 is installed at the image forming apparatus body 100), the drive roller 12A (roller member) is supported in a freely rotatable manner at the intermediate transfer belt device 15 by the front side bearing 171 and the rear side bearing 172. When the intermediate transfer belt device 15 is then pulled out from the image forming apparatus body 100 and the holding cover 175 is taken out from the rear frame 110, the drive roller 12A is supported at the intermediate transfer belt device 15 by the front side bearing 171 and the sub-bearing 173. This means that even when the intermediate transfer belt device 15 is pulled out from the image forming apparatus body 100 and the intermediate transfer belt device 15 is cantilever-supported by the slide rails 140 and 150 so that frame deformation occurs, an end (rear side shaft 12Ab) of the drive roller 12A is supported by the sub-bearing 173 provided with clearance. The inconvenience of an unbalanced load accompanying frame deformation being applied to the drive roller 12A is therefore suppressed. When the drive roller 12A is supported by three or more bearings, (for example, when a main bearing is installed with no clearance at the position of the sub-bearing 173), when the intermediate transfer belt device 15 is then cantilever-supported by the slide rails 140 and 150 during maintenance so that the frame is deformed, the drive roller 12A is subjected to an unbalanced load accompanying deformation of the frame, the straightness of the drive roller 12A is lowered, and coaxiality of the plurality of bearings collapses. As a result, when the intermediate transfer belt device 15 operates normally, the drive roller 12A is subjected to substantial stress during the rotational period and may break in the worst case scenario. When the sub-bearing 173 is not provided and the drive roller 12A is supported by just two bearings, the posture of the drive roller 12A is not stable until the two bearings are installed at the intermediate transfer belt device 15. This is detrimental to the assembly and maintenance of the intermediate transfer belt device 15. In the second embodiment, the sub-bearing 173 having clearance is provided in addition to the front side bearing 171 and the rear side bearing 172. This improves ease of assembly of the intermediate transfer belt device 15 and makes maintenance such as changing the drive roller 12A while the intermediate transfer belt device 15 is pulled out from the image forming apparatus body 100 straightforward.
This is explained in detail in the following using
The sub-bearing 173 is formed of a low-friction material such as polyacetal or oil-impregnated sintered metal. A clearance δ with respect to the rear side shaft 12Ab of the drive roller 12A (see
Next, a procedure for assembling the drive roller 12A to the frame of the intermediate transfer belt device 15 during manufacture is explained. Referring to
In the second embodiment, the position of the center of gravity of the drive roller 12A is between the front side bearing 171 and the sub-bearing 173. When the position of the center of gravity of the drive roller 12A is not between the front side bearing 171 and the sub-bearing 173, when the drive roller 12A is supported by the front side bearing 171 and the sub-bearing 173, according to lever theory, a substantial load is applied to the front side bearing 171 and the sub-bearing 173 and the drive roller 12A is supported in an unstable manner.
After this, the encoder disc 178 and the gear 177 are arranged on the rear side shaft 12Ab and the encoder sensor 179 is also fitted at this time. The drive motor 70 and the holding cover 175 supported by the rear side bearing 172 are then inserted from the rear of the drive roller 12A, as shown in
Referring to
The following configuration enables the rear side shaft 12Ab and the rear side bearing 172 to engage in a smooth manner. Referring to
When a distance in a vertical direction from an internal diameter section of the rear side bearing 172 to the upper end of the tapered section 175a of the holding cover 175 is taken to be M3, and the height of an R-section, which is a fillet formed between the internal diameter section of the rear side bearing 172 and an axial face of the rear side bearing 172, is taken to be M4, it is preferable for the relationship M2+M4>M3 to be satisfied. By forming the fillet at the internal diameter section (R-section) of the rear side bearing 172 in this manner, after the rear side shaft 12Ab of the drive roller 12A is scooped up by the tapered section 175a of the holding cover 175, a series of operations is carried out smoothly until the rear side shaft 12Ab is inserted to the rear side bearing 172. In the second embodiment, a distance D1 of 417 millimeters, a distance D2 of 442 millimeters, a clearance δ of 1 millimeter, a distance M1 of 2 millimeters, a distance M2 of 1 millimeter, a distance M3 of 1 millimeter, and a distance M4 of 0.3 millimeter are set in the second equation.
An explanation is given below of maintenance of the periphery of the drive roller 12A of the intermediate transfer belt device 15. Maintenance such as changing is carried out as a result of degradation etc. of the rubber layer of the surface for the drive roller 12A. Checking or changing of parts is carried out when the gear 177 of the drive roller 12A degrades due to wear or the encoder disc 178 or the encoder sensor 179 becomes damaged. For example, when the gear 177 is changed, the intermediate transfer belt device 15 is pulled out from the image forming apparatus body 100 as shown in
The case of installing a normal bearing (referred to as a “center bearing” below where clearance δ with the rear side shaft 12Ab is not provided) in place of the sub-bearing 173 of the second embodiment is also considered. In this event, the rear side bearing 172 is installed with the drive roller 12A fixed by the front side bearing 171 and the center bearing. Ease of assembly is then good because the drive roller 12A is fixed to the center bearing during manufacture. However, the three bearings are no longer lined up along a straight line in a state where the intermediate transfer belt device 15 is pulled out as explained above during maintenance. It is therefore necessary to consider that stress is not to be applied to the drive roller 12A by making the rigidity of the holding cover 175 holding the rear side bearing 172 sufficiently weak. When the drive roller 12A is changed with the intermediate transfer belt device 15 pulled out, the rear side bearing 172 is fixed on a straight line formed by the front side bearing 171 and the center bearing with the frame flexed. When the intermediate transfer belt device 15 is then installed in the image forming apparatus body 100 and flexing of the frame is eliminated, the three bearings are lined up along the same straight line. When stress is not released to the drive roller 12A by making rigidity of the holding cover 175 sufficiently weak, the drive roller 12A is subjected to stress every time rotation takes place and fatigue failure will occur. However, when the holding cover 175 is formed from low-rigidity material such as resin, various inconveniences occur such as it being difficult for heat occurring at the drive motor 70 etc. to be dissipated occur. In the second embodiment, in addition to the front side bearing 171 and the rear side bearing 172, the sub-bearing 173 having sufficient clearance is provided. Ease of assembly of the intermediate transfer belt device 15 is therefore improved without side effects occurring. Maintenance such as changing of the drive roller 12A with the intermediate transfer belt device 15 pulled out from the image forming apparatus body 100 can then be carried out easily.
Referring to
In the second embodiment, as in the first embodiment, the front frame 115 having a smaller projecting surface than the inner periphery of the intermediate transfer belt 8 (belt member) as viewed from the front is cantilever-supported with respect to the rear frame 110. The mechanical strength with respect to force applied to the intermediate transfer belt device 15 (belt device) is also effectively increased when the intermediate transfer belt device 15 is pulled out from the image forming apparatus body 100. It is therefore possible to increase ease of maintenance of the intermediate transfer belt device 15 including changing of the intermediate transfer belt 8 without deformation of the intermediate transfer belt device 15 occurring.
A third embodiment of the present invention is now explained in detail using
The intermediate transfer belt device 15 of the third embodiment has the same configuration as that of the second embodiment. In the intermediate transfer belt device 15 of the third embodiment, the holding cover 175 (holding member) is installed so as to be freely attachable/detachable with respect to the main frame 110a of the rear frame 110. Referring to
Here, the positioning stud 110d of the rear frame 110 is designed so that the positional relationship with the front frame 115 is highly precise. Parts (for example, various roller members etc.) where the relative positional relationship with the front frame 115 is important are then set so that the position is decided by the front frame 115 and the main frame 110a. With regards to this, the sub-frame 110b is not designed so as to have a function strongly supporting the main frame 110a so as to give a highly precise positional relationship with the front frame 115. The positional relationship of the holding cover 175 with respect to the front frame 115 can then be made highly precise by installing the holding cover 175 at the main frame 110a via the studs 110e. The drive roller 12A is then installed highly precisely at the intermediate transfer belt device 15.
In the third embodiment, the holding cover 175 is installed at the main frame 110a as a result of the four boss sections 175b abutting with the facets of the studs 110e of the main frame 110a. It is therefore possible to position the holding cover 175 with high-precision with respect to the main frame 110a without setting overall flatness over a broad range of an opposing surface of the holding cover 175 with a high degree of accuracy, by setting just the flatness of the four boss sections 175b of the holding cover 175 in a highly precise manner. The yield for the holding cover 175 is therefore increased and the cost of parts lowered.
In the third embodiment, a seal plate 192 and a sponge seal 193 are disposed as a seal member between the holding cover 175 and the rear frame 110.
Specifically, the seal plate 192 taken as a seal member is formed using flexible material such as Mylar and is affixed to either the holding cover 175 or the rear frame 110 using double-sided tape. This prevents suspended matter such as toner from encroaching to between the holding cover 175 and the rear frame 110 from above. Further, the sponge seal 193 taken as a seal member is a rectangular toroidal resilient member formed of polyurethane foam etc. affixed to the outer peripheral surface of the surface facing the holding cover 175 facing the rear frame 110. The sponge seal 193 prevents foreign matter such as toner from encroaching between the holding cover 175 and the rear frame 110.
In the third embodiment, as in each of the other embodiments, the front frame 115 having a projecting surface smaller than the inner periphery of the intermediate transfer belt 8 (belt member) as viewed from the front is cantilever-supported with respect to the rear frame 110. Mechanical strength with respect to force applied to the intermediate transfer belt device 15 (belt device) when the image forming apparatus body 100 is pulled out is therefore effectively increased. It is therefore possible to improve ease of maintenance of the intermediate transfer belt device 15 including changing of the intermediate transfer belt 8 without deformation of the intermediate transfer belt device 15.
The present invention is also applicable to a belt device using a transfer belt (an endless belt-shaped transfer member functioning in the same way as the secondary transfer roller in this embodiment) as a belt member.
In the above-explained embodiments, the present invention is applied to the intermediate transfer belt 8. However, the present invention is also applicable to a transfer belt. The present invention is also applicable to a photosensitive belt.
The present invention is not limited to the above-explained embodiments and it is clear that appropriate modifications of the embodiments are possible other than suggested here while remaining within the scope of the technical concept of the present invention. The number, position, and shape etc. of the members of the configuration are not limited to these embodiments and a preferred number, position, and shape etc. can be adopted in implementing the present invention.
The present invention thus provides a belt device and an image forming apparatus where a front frame having a projecting surface smaller than an inner periphery of the belt member as viewed from the front is cantilever-supported with respect to a rear frame. Strength with respect to force applied to the belt device when pulled out from the image forming apparatus body is therefore effectively increased. Ease of maintenance of the device including changing of the belt member is therefore increased without deformation occurring at the device.
A seal member is disposed between the holding member and the rear frame. The holding member is made from aluminum. The sub-bearing is formed of a low friction material. The image forming apparatus includes a fixing member that fixes the frame to the body in a state where the belt device is housed in the body is disposed in a freely detachable manner.
Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.
Number | Date | Country | Kind |
---|---|---|---|
2007-226027 | Aug 2007 | JP | national |
2008-130280 | May 2008 | JP | national |
The present application is a continuation of U.S. Application Ser. No. 13/034,744 filed Feb. 25, 2011 now U.S. Pat. No. 8,103,190, which is a continuation of U.S. application Ser. No. 12/199,029 filed Aug. 27, 2008 now U.S. Pat. No. 7,920,808, and is based upon and claims the benefit of priority from prior Japanese Patent Applications Nos. 2007-226027 and 2008-130280 filed Aug. 31, 2007, and May 19, 2008, respectively, the entire contents of each of which are incorporated herein by reference in their entirety.
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Number | Date | Country | |
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Parent | 13034744 | Feb 2011 | US |
Child | 13309016 | US | |
Parent | 12199029 | Aug 2008 | US |
Child | 13034744 | US |