JP4259073B2 - Tension release device and image forming apparatus using the same - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, or a facsimile using an electrophotographic method, and in particular, an image forming apparatus including a tension applying mechanism that applies / releases tension to an endless belt-like member such as an intermediate transfer belt. It relates to the device.
[0002]
[Prior art]
Conventionally, among image forming apparatuses such as copying machines, printers, and facsimiles to which the above-described electrophotographic method is applied, image forming apparatuses that form color images include a plurality of colors corresponding to each color such as yellow, magenta, cyan, and black. After the toner image of each color such as yellow, magenta, cyan, black, etc. sequentially formed on the photosensitive drum is primarily transferred so as to be superimposed on the intermediate transfer belt, the intermediate transfer belt is provided. The so-called “tandem type” is configured to form a full-color image by transferring and fixing the toner images of yellow, magenta, cyan, black, etc. transferred in multiple layers onto a recording sheet at once. There is an image forming apparatus.
[0003]
In addition, the color image forming apparatus is configured to sequentially form toner images of predetermined colors such as yellow, magenta, cyan, and black on a single photosensitive drum, and to form yellow and magenta formed on the photosensitive drum. The toner images of cyan, black, etc. are sequentially transferred onto the intermediate transfer belt in order to overlap each other, and then the toner images of yellow, magenta, cyan, black etc. There is a so-called “multiple-type” image forming apparatus configured to form a full-color image by transferring and fixing onto a recording sheet.
[0004]
In the case of these image forming apparatuses, for example, if the intermediate transfer belt is stored for a long period of time with the tension applied, the intermediate transfer belt is curled. Therefore, in order to prevent the wrinkle from occurring on the intermediate transfer belt, it is necessary to loosen the tension of the intermediate transfer belt.
[0005]
In the case of the image forming apparatus, it is necessary to loosen the tension of the intermediate transfer belt and remove the belt when replacing the intermediate transfer belt or when performing maintenance inside the intermediate transfer belt unit.
[0006]
In the former case, the amount by which the tension of the intermediate transfer belt is relaxed must be kept to a minimum so that the loose intermediate transfer belt does not come into contact with other adjacent parts and are damaged. Further, in the latter case, there is a conflicting need to loosen the tension of the intermediate transfer belt as much as possible so that the intermediate transfer belt can be easily removed.
[0007]
On the other hand, conventionally, a certain amount of curl is generated on the intermediate transfer belt, and a mechanism for loosening the tension of the intermediate transfer belt is not provided during long-term storage, or the tension applying mechanism is not provided with the intermediate transfer belt. Only a mechanism for easing the minimum tension is laid, and when the belt is removed, a completely different mechanism is provided so that the tension of the intermediate transfer belt is relaxed as much as possible.
[0008]
[Problems to be solved by the invention]
However, not only the former prior art but also the latter prior art has a problem of providing a separate mechanism. Further, if the above separate mechanisms are supplemented by a single mechanism, the following problems arise. That is, if a tension applying mechanism that applies tension to the intermediate transfer belt is used to largely separate the intermediate transfer belt to a position where the intermediate transfer belt can be removed, a pressure member such as a spring that applies tension to the intermediate transfer belt is originally used. Furthermore, since compression (it is possible also by pulling) and operation force becomes excessive, it had the problem that operation was difficult for a weak person.
[0009]
Further, in the mechanism in which the tension applying mechanism for the intermediate transfer belt and the belt meandering adjustment mechanism are provided together, the belt meandering adjustment mechanism is also moved by the operation performed when the tension of the intermediate transfer belt is released, and the tension of the intermediate transfer belt is released. When the return operation is performed, the meandering of the belt must be adjusted at the same time, and the operation becomes complicated. Furthermore, it is difficult to move the mechanism for applying tension to the intermediate transfer belt directly with a cam or the like, and it is necessary to provide a mechanism for releasing the tension of the intermediate transfer belt and a mechanism for applying tension separately, and the structure is large. In addition, it had another problem of becoming complicated.
[0010]
Accordingly, the present invention has been made to solve the above-described problems of the prior art, and the object of the present invention is to loosen the tension of the endless belt-like member to the minimum necessary, and the endless belt-like member. An object of the present invention is to provide an image forming apparatus capable of performing a removably loosening operation with a simple mechanism and a small force.
[0011]
Another object of the present invention is to provide a belt meandering adjustment mechanism for releasing the tension and returning the endless belt-like member in a mechanism provided with a tension applying mechanism for the endless belt-like member and a belt meandering adjustment mechanism. It is an object of the present invention to provide an image forming apparatus that can be performed without moving the image forming apparatus, and that is excellent in operability without making the structure large and complicated.
[0012]
[Means for Solving the Problems]
To achieve the above object, the invention described in claim 1 is a tension release device for releasing tension of an endless belt member stretched by a plurality of rolls.
A slide member that slidably supports a roll that applies tension to the endless belt member in a direction in which the tension is loosened; biasing means that biases the slide member in a direction in which tension is applied to the belt member; Moving means for moving the slide member in the direction of loosening the tension And meandering correction means for correcting meandering of the belt member by tilting one end of a roll that applies tension to the endless belt member. With
The moving means has a plurality of stop positions for stopping the slide member at different positions. And at least one of the moving means and the meandering correction device can be fixed at a predetermined position at at least one stop position of the moving means, and when the moving means loosens the tension of the belt member, It was configured to restrict the movement of the meandering correction means This is a tension release device.
[0018]
further, Claim 2 In the invention described in the item 1, the movement of the meandering correction unit is regulated in conjunction with the movement of the moving unit to loosen the tension of the belt member. Claim 1 It is a tension release apparatus of description.
[0019]
The invention described in claim 3 is characterized in that the means for regulating the movement of the meandering correction means comprises a guide member for guiding the slide member. Claim 2 It is the tension release mechanism described.
[0020]
Furthermore, Claim 4 The image forming apparatus includes a tension releasing mechanism that forms an image using an endless image carrier belt stretched by a plurality of rolls and releases the tension of the image carrier belt. In
The tension release mechanism biases a roll for applying tension to the endless belt member so as to be slidable in a direction in which the tension is loosened, and the slide member in a direction to apply tension to the belt member. Biasing means and moving means for moving the slide member in the direction of loosening the tension And meandering correction means for correcting meandering of the belt member by tilting one end of a roll that applies tension to the endless belt member. With
The moving means has a plurality of stop positions for stopping the slide member at different positions. And at least one of the moving means and the meandering correction device can be fixed at a predetermined position at at least one stop position of the moving means, and when the moving means loosens the tension of the belt member, It was configured to restrict the movement of the meandering correction means An image forming apparatus characterized by the above.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0022]
Embodiment 1
FIG. 2 shows a so-called “tandem type” digital color copying machine as an image forming apparatus according to Embodiment 1 of the present invention.
[0023]
In FIG. 2, reference numeral 1 denotes a main body of a tandem type digital color copying machine. A platen cover 3 that presses a document 2 onto a platen glass 5 is disposed on an upper portion of one end side of the digital color copying machine main body 1. An image reading device 4 that reads an image of the document 2 placed on the platen glass 5 is provided. The image reading device 4 illuminates a document 2 placed on a platen glass 5 with a light source 6, and reflects a reflected light image from the document 2 from a full-rate mirror 7, half-rate mirrors 8 and 9, and an imaging lens 10. The image reading element 11 composed of a CCD or the like is scanned and exposed through a reduction optical system, and the color material reflected light image of the document 2 is formed at a predetermined dot density (for example, 16 dots / mm) by the image reading element 11. It is configured to read.
[0024]
The color material reflected light image of the document 2 read by the image reading device 4 is subjected to image processing as, for example, document reflectance data of three colors of red (R), green (G), and blue (B) (8 bits each). The image processing apparatus 12 sends a shading correction, a position shift correction, a lightness / color space conversion, a gamma correction, a frame deletion, a color / movement to the reflectance data of the document 2. Predetermined image processing such as editing is performed.
[0025]
The image data that has been subjected to the predetermined image processing by the image processing apparatus 12 as described above is an original of four colors of yellow (Y), magenta (M), cyan (C), and black (K) (8 bits each). As described below, the color material gradation data (raster data) is converted into black (K), yellow (Y), magenta (M), and cyan (C) image forming stations 13K, 13Y, 13M, 13C ROSs 14K, 14Y, 14M and 14C (Raster Output Scanners), and these ROSs 14K, 14Y, 14M and 14C perform image exposure with laser light according to the original color material gradation data of a predetermined color. .
[0026]
By the way, inside the tandem type digital color copying machine body 1, as described above, four image forming stations 13K, 13Y of black (K), yellow (Y), magenta (M), and cyan (C) are provided. , 13M, 13C are arranged in parallel at a certain distance in the horizontal direction.
[0027]
These four image forming stations 13K, 13Y, 13M, and 13C are all configured in the same manner, and are roughly divided into a photosensitive drum 15 that rotates at a predetermined rotational speed in the direction of the arrow, and the photosensitive drum 15. Primary charging scorotron 16 for uniformly charging the surface of the photosensitive drum 15, ROS 14 as an image exposure device for forming an electrostatic latent image by exposing an image corresponding to each color on the surface of the photosensitive drum 15, and a photosensitive member The developing unit 17 for developing the electrostatic latent image formed on the drum 15 and a cleaning device 18 are configured.
[0028]
As shown in FIG. 2, the ROS 14 modulates the semiconductor laser 19 according to the gradation data, and emits a laser beam LB from the semiconductor laser 19 according to the gradation data. The laser beam LB emitted from the semiconductor laser 19 is deflected and scanned by the rotary polygon mirror 22 via the reflection mirrors 20 and 21, and again carries an image via the reflection mirrors 20 and 21 and the plurality of reflection mirrors 23 and 24. Scanning exposure is performed on the photosensitive drum 15 as a body.
[0029]
From the image processing apparatus 12, each color is supplied to the image forming stations 13K, 13Y, 13M, and 13C of ROS 14K, 14Y, 14M, and 14C of black (K), yellow (Y), magenta (M), and cyan (C). Image data (raster data) are sequentially output, and laser beams LB emitted according to the image data from these ROSs 14K, 14Y, 14M, and 14C are applied to the surfaces of the respective photosensitive drums 15K, 15Y, 15M, and 15C. An electrostatic latent image is formed by scanning exposure. The electrostatic latent images formed on the photosensitive drums 15K, 15Y, 15M, and 15C are respectively black (K), yellow (Y), magenta (M), and cyan by the developing units 17K, 17Y, 17M, and 17C. It is developed as a toner image of each color of (C).
[0030]
Black (K), yellow (Y), magenta (M), and cyan (C) sequentially formed on the photosensitive drums 15K, 15Y, 15M, and 15C of the image forming stations 13K, 13Y, 13M, and 13C, respectively. The toner images of the respective colors are transferred in multiple by primary transfer rolls 26K, 26Y, 26M, and 26C onto an intermediate transfer body belt 25 as an intermediate transfer body disposed below each image forming station 13K, 13Y, 13M, and 13C. Is done. The intermediate transfer belt 25 includes a drive roll 27, a stripping roll 28, a tension / steering roll 29 that also functions as a tension roll and a steering roll, an idle roll 30, a backup roll 31, and an idle roll 32. The drive roll 27 is driven to rotate and is circulated at a predetermined speed in the direction of the arrow. As the intermediate transfer belt 25, for example, a flexible synthetic resin film such as polyimide is formed in a strip shape, and both ends of the synthetic resin film formed in a strip shape are connected by means such as welding, thereby being endless. A belt-shaped one is used.
[0031]
The black (K), yellow (Y), magenta (M), and cyan (C) toner images transferred onto the intermediate transfer belt 25 in multiple layers are in contact with the backup roll 31, and the secondary transfer roll 33. Accordingly, the recording paper 34 that has been secondarily transferred onto the recording paper 34 as a recording medium by the pressure contact force and electrostatic force, and the toner image of each color is transferred to the fixing device 37 by the two transport belts 35 and 36. Be transported. The recording paper 34 onto which the toner images of the respective colors have been transferred undergoes a fixing process with heat and pressure by a fixing device 37 and is discharged onto a discharge tray 38 provided outside the copying machine main body 1.
[0032]
As shown in FIG. 2, the recording paper 34 has a predetermined size from any of a plurality of paper feed trays 39, 40, 41, and a pair of paper feed rollers 42 and a pair of paper transport rollers 43, 44. , 45 is temporarily transported to the registration roll 47 via a paper transport path 46. The recording paper 34 supplied from any one of the paper feed trays 39, 40, 41 is sent onto the intermediate transfer belt 25 by a registration roll 47 that is rotationally driven at a predetermined timing.
[0033]
In the four black, yellow, magenta, and cyan image forming stations 13K, 13Y, 13M, and 13C, as described above, black, yellow, magenta, and cyan toner images are respectively stored in predetermined colors. It is formed sequentially at the timing.
[0034]
The photosensitive drums 15K, 15Y, 15M, and 15C, after the toner image transfer process is completed, the residual toner and paper dust are removed by the cleaning devices 18K, 18Y, 18M, and 18C, and the next image formation is performed. Prepare for the process. Further, the residual toner is removed from the intermediate transfer belt 25 by the belt cleaner 48.
[0035]
By the way, in this embodiment, in the tension release device for releasing the tension of the endless belt member stretched by a plurality of rolls, the roll for applying tension to the endless belt member is set in the direction of loosening the tension. A sliding member that slidably supports; a biasing unit that biases the slide member in a direction in which a tension is applied to the belt member; and a moving unit that moves the slide member in a direction in which the tension is loosened. Is configured to have a plurality of stop positions for stopping the slide member at different positions.
[0036]
Further, in this embodiment, the plurality of stop positions of the moving means are a first stop position for preventing the belt member from generating curl and a second stop for replacing the belt member. Configured to be position.
[0037]
Furthermore, in this embodiment, the moving means is constituted by an eccentric cam and a roller-like member that rolls in contact with the surface of the eccentric cam.
[0038]
FIG. 1 is a configuration diagram showing a tension release mechanism according to the first embodiment.
[0039]
The tension release mechanism 50 includes slide plates 51 and 52 as slide members that slidably support a tension / steering roll 29 that applies tension to the intermediate transfer belt 25 as an endless belt member in a direction in which the tension is loosened. Both ends of the tension / steering roll 29 are rotatably attached to the front ends of the slide plates 51 and 52. The slide plates 51 and 52 are rotatably attached to the distal end portions of the slide plates 51 and 52. Of the slide plates, the rear slide plate 51 is slidably mounted along the arrow direction with respect to the rear frame 53 by a slide rail 54. Further, a pressure spring 56 as an urging means is interposed between the proximal end portion 51 a of the slide plate 51 and the upright plate 55 attached to the rear frame 53, and the distal end portion of the slide plate 51. Is urged in a protruding direction, and a predetermined tension is applied to the intermediate transfer belt 25 by a tension / steering roll 29.
[0040]
On the other hand, among the slide plates, the front slide plate 52 slides with respect to the swing frame 58 as meandering correction means swingably attached to the front surface of the front frame 57 as shown in FIG. The rail 51c is slidably mounted along the arrow direction. Further, a pressure spring 60 as an urging means is interposed between the vicinity 52 a of the base end portion of the slide plate 52 and an upright plate 59 provided on the swing frame 58. The front end is urged in the protruding direction, and a predetermined tension is applied to the intermediate transfer belt 25 by the tension / steering roll 29.
[0041]
Further, as shown in FIGS. 1 and 3, tension release rollers 61 and 62 as roll-shaped members are rotatably attached to the base end portions of the tension plates 51 and 52, respectively. The tension release rollers 61 and 62 are substantially disposed on an extension of the pressure acting line of the pressure spring that urges the tension plates 51 and 52. The tension release rollers 61 and 62 allow the pressure springs 56 and The force that moves 60 is efficiently applied to the tension plates 51 and 52. Further, tension release cams 63 and 64, which are eccentric cams, are arranged near the base ends of the tension plates 51 and 52 and closer to the pressure springs 56 and 60 than the base ends. The tension release cams 63 and 64 and the tension release rollers 61 and 62 constitute a moving means. As shown in FIG. 1, both the tension release cams 63 and 64 are fixed to the both ends of the camshaft 65 at the same position, and the camshaft 65 rotates between the rear frame 53 and the front frame 57. It is attached freely. The camshaft 65 is rotationally driven by a predetermined amount in a predetermined direction by a driving means (not shown).
[0042]
As shown in FIGS. 4 and 5, the tension release cams 63 and 64 are provided with curved portions 63 a and 64 a that are curved so that the radius gradually increases from the vicinity of the camshaft 65 on the outer peripheral surface thereof. In addition, the tension release rollers 61 and 62 of the tension plates 51 and 52 are fitted into the curved portions 63a and 64a of the tension release cams 63 and 64, whereby the tension plate to which the tension release rollers 61 and 62 are attached. There are provided a first stop position 66 and a second stop position 67, which are recesses for stopping 51 and 52. The first stop position 66 is provided in the middle of the curved portions 63a and 64a of the tension release cams 63 and 64. By moving the tension plates 51 and 52 in a direction to loosen the belt 25 by a predetermined amount, The belt 25 is set at a position for preventing curling from occurring. The second stop position 67 is provided at the distal end portion (maximum outer diameter portion) of the curved portions 63a, 64a of the tension release cams 63, 64, and the tension plates 51, 52 are belted by a large predetermined amount. By moving the belt 25 in the loosening direction, the belt 25 is set to a position for replacement.
As in the embodiment shown in FIG. 5, the second stop position 67 does not have to be formed as a recess.
[0043]
Furthermore, in this embodiment, the roll for applying tension to the endless belt member is provided with meandering correcting means for correcting the meandering of the belt member by tilting one end of the roll.
[0044]
That is, in this embodiment, as shown in FIG. 1, a swing frame 58 that constitutes the meandering correction means 100 is provided, and the swing frame 58 is swingable on the swing center 70 as a fulcrum. The swing frame 58 is attached to the frame 57 and urged by the pressure spring 81 so as to rotate in the clockwise direction. Further, a swinging roller 82 is rotatably provided at the base end portion of the swinging frame 58, and the swinging roller 82 is eccentric so that the outer diameter of the peripheral surface gradually increases. It is in contact with the cam 83. The eccentric cam 83 is rotationally driven via a driven gear 86 by a drive gear 85 that is rotationally driven by a drive motor 84. Then, the base end portion of the swing frame 58 is moved along the vertical direction via the swing roller 82 by rotating the eccentric cam 83, and is attached to the distal end portion of the swing frame 58. One end of the tension / steering roll 29 is tilted, and as a result, the meandering of the intermediate transfer belt 25 stretched around the tension / steering roll 29 is corrected.
[0045]
In this embodiment, at least one of the moving means and the meandering correction device can be fixed at a predetermined position at at least one stop position of the moving means.
[0046]
Further, in this embodiment, the means for fixing at least one of the moving means and the meandering correction means at a predetermined position penetrates at least one member of the moving means and the meandering correction means through the fixed member. It is comprised so that it may consist of a shaft-shaped member.
[0047]
In this embodiment, the movement means regulates the movement of the meandering correction means when the tension of the belt member is relaxed. The regulation of the movement of the meandering correction means is performed in conjunction with the movement of the moving means to loosen the tension of the belt member, for example.
[0048]
Furthermore, in this embodiment, the means for restricting the movement of the meandering correction means is constituted by a guide member for guiding the slide member.
[0049]
That is, in this embodiment, as shown in FIGS. 1, 3, 4, and 6, the front slide plate 52, the tension release cam 64, the swing frame 58, the front frame 57, the drawer, Insertion holes 90 to 94 for inserting a fixed shaft 88 as a shaft member are formed at predetermined positions of the frame 87. The drawer frame 87 is a frame for pulling out the transfer belt unit to the front side of the copying machine main body 1. Then, by inserting the fixed shaft 88 into the insertion holes 90 to 94 of the front side slide plate 52, the tension release cam 64, the swing frame 58, the front frame 57, and the drawer frame 87, the slide plate 52 and the swing frame 58 are fixed to the front frame 57 and the drawer frame 87. The positions where the front slide plate 52 and the swing frame 58 are fixed are set to positions corresponding to the first stop position 66 of the tension release cam 64, and the intermediate transfer belt 25 is curled. It is possible to prevent the front-side slide plate 52 and the swing frame 58 from moving unnecessarily at the first stop position 66 that prevents the occurrence of the occurrence, such as when the digital color copying machine is transported. It has become.
[0050]
Further, as shown in FIG. 1, the front frame 57 is provided with a swing regulating roller 95 that regulates the swing of the swing frame 58. A stud 96 erected on the frame 57 is rotatably attached to the tip end. As shown in FIG. 8, the swing restricting roller 95 is configured such that when the slide frame 52 is moved in the tension release direction, the upper end edge of the slide frame 52 comes into contact with the swing frame 52 attached to the slide frame 52. The moving frame 58 is configured to be restricted from swinging.
[0051]
In the above configuration, in the image forming apparatus according to this embodiment, an operation for loosening the tension of the endless belt-like member to the minimum necessary and an operation for loosening the endless belt-like member so as to be removable are performed as follows. It is possible to carry out with a simple mechanism and a small force.
[0052]
Further, in this embodiment, in the mechanism in which the tension applying mechanism for the endless belt-like member and the belt meandering adjustment mechanism are provided as follows, the tension release and return operation of the endless belt-like member is adjusted for belt meandering adjustment. The operation can be performed without moving the mechanism, and the configuration is excellent in operability without being large and complicated.
[0053]
That is, in the digital color copying machine according to this embodiment, when the apparatus configured as shown in FIG. 2 is assembled at the factory and the digital color copying machine is shipped, a predetermined tension is applied to the intermediate transfer belt 25. In such a state, curling may occur on the intermediate transfer belt 25, particularly in the drive roll 27 or the tension / steering roll 29 having a large winding angle.
[0054]
Therefore, in the digital color copying machine according to this embodiment, as shown in FIG. 1, a hexagonal column-shaped rotating portion provided at the front end of the camshaft 65 prior to shipment of the digital color copying machine. 65a is rotated clockwise by a driver, spanner or the like (not shown) having a shape matching the rotation portion 65a, and the tension release cams 63 and 64 attached to the camshaft 65 are rotated as shown in FIG. It is assumed that the tension release rollers 61 and 62 of the tension plates 51 and 52 are fitted to the stop position 66 of the first stop.
[0055]
By doing so, the tension plates 51 and 52 are pressurized when the tension release rollers 61 and 62 provided at the base ends of the tension plates 51 and 52 rotate the curved portions 63a and 64a of the tension release cams 63 and 64, respectively. Slides a predetermined amount toward the base end side against the urging force of the springs 56 and 60. Then, the tension / steering roll 29 supported by the tension plates 51 and 52 moves in the direction of loosening the tension of the intermediate transfer belt 25 as shown in FIG. It is possible to prevent the tension on the intermediate transfer belt 25 from being curled due to the loosened tension.
[0056]
At this time, the first stop position 66 of the tension release cams 63 and 64 is set to a position that prevents the intermediate transfer belt 25 from being curled, and the intermediate transfer belt 25 is unnecessarily loosened. Therefore, it is possible to prevent the intermediate transfer belt 25 from being damaged due to contact with other members during transportation.
[0057]
When the digital color copying machine is installed and used at a predetermined location, the service engineer rotates the cam shaft 65 in the counterclockwise direction so that a predetermined tension is applied to the intermediate transfer body belt 25. It comes to join.
[0058]
On the other hand, in the above digital color copying machine, when maintenance or replacement of the intermediate transfer belt 25 is performed, as shown in FIG. 1, a hexagonal column-shaped rotating portion provided at the front end of the camshaft 65 is used. The tension release cam 63 attached to the camshaft 65, as shown in FIGS. 8 and 9, is rotated clockwise by a driver, spanner or the like (not shown) having a shape matching the rotation portion 65a. The tension release rollers 61 and 62 of the tension plates 51 and 52 are engaged with the second stop position 67 of 64.
[0059]
By doing so, the tension plates 51 and 52 are pressurized when the tension release rollers 61 and 62 provided at the base ends of the tension plates 51 and 52 rotate the curved portions 63a and 64a of the tension release cams 63 and 64, respectively. Slides a predetermined amount toward the base end side against the urging force of the springs 56 and 60. Then, as shown in FIG. 8, the tension / steering roll 29 supported by the tension plates 51 and 52 moves in a direction in which the tension of the intermediate transfer belt 25 is greatly loosened. The applied tension is released and the intermediate transfer belt 25 can be removed.
[0060]
At this time, if the tension plates 51 and 52 are moved by the tension release cams 63 and 64 in a direction in which the tension of the intermediate transfer body belt 25 is greatly relaxed, the tension plates 51 and 52 are moved against the tension plates 51 and 52. A rotational moment that rotates in the clockwise direction acts.
[0061]
Then, the tension plates 51 and 52 are slidably attached to the swing plate 58, and the swing plate 58 is rotatable about the swing center 80 on the front frame 57. If a counterclockwise rotational moment acts on the tension plates 51 and 52 in this state, the swing plate 58 also rotates counterclockwise, and the meandering correction state of the intermediate transfer belt 25 is shifted. There is a risk of it.
[0062]
Therefore, in this embodiment, as shown in FIG. 8, when the tension plates 51 and 52 are moved in the direction in which the tension of the intermediate transfer body belt 25 is greatly relaxed, the upper surface 51 b of the base end portion of the tension plate 51 is As shown in FIG. 9, the upper surface 51b of the base end portion of the tension plate 51 is guided by the rotation of the swing restricting roller 95 and abuts against the swing restricting roller 95 provided on the front frame 57. The position is regulated so as not to rotate in the turning direction.
[0063]
Therefore, even when the tension plates 51 and 52 are largely moved, it is possible to prevent the meandering correction unit of the intermediate transfer belt 25 from being affected.
[0064]
As described above, in the above embodiment, the moving means for releasing the tension of the intermediate transfer body belt 25 includes the tension releasing rollers 61 and 62 and the tension releasing cams 63 and 64, and the tension releasing cam. Since 63 and 64 have two stop positions, the intermediate transfer member can be obtained by rotating the camshaft 65 to which the tension release cams 63 and 64 are attached with a small force by rotating means such as a driver. It is possible to perform the work of loosening the tension of the belt 25 to the minimum necessary and the work of loosening the intermediate transfer belt 25 so as to be detachable with a simple mechanism and a small force.
[0065]
When the present inventor measured the rotational torque of the camshaft 65, a conventional rotational torque of about 20 kgf · cm was required. However, in the present invention, the rotational torque can be significantly reduced to about 11 kgf · cm. I found it possible.
[0066]
Further, according to the above embodiment, in the mechanism in which the tension applying mechanism to the intermediate transfer belt 25 and the belt meandering adjustment mechanism are provided, the tension release and return operations of the intermediate transfer belt 25 are performed using the belt meandering adjustment mechanism. It can be performed without moving, and the structure is excellent in operability without being large and complicated.
[0067]
【The invention's effect】
As described above, according to the present invention, the operation of loosening the tension of the endless belt-like member to the minimum necessary and the operation of loosening the endless belt-like member so as to be removable can be performed with a simple mechanism and a small force. It is possible to provide an image forming apparatus capable of achieving the above.
[0068]
Further, according to the present invention, in the mechanism in which the tension applying mechanism for the endless belt-like member and the belt meandering adjustment mechanism are provided, the tension release and the return operation of the endless belt-like member are performed without moving the belt meandering adjustment mechanism. In addition, it is possible to provide an image forming apparatus with excellent operability without having a large and complicated configuration.
[Brief description of the drawings]
FIG. 1 is a perspective configuration diagram showing a main part of an image forming apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a schematic configuration diagram showing a tandem type digital color copying machine as an image forming apparatus according to Embodiment 1 of the present invention.
FIG. 3 is a perspective configuration diagram showing the main part of the image forming apparatus according to Embodiment 1 of the present invention.
FIG. 4 is a front structural view showing a main part of the image forming apparatus according to Embodiment 1 of the present invention.
FIG. 5 is a configuration diagram showing a tension release cam.
FIG. 6 is a bottom configuration diagram showing the main part of the image forming apparatus according to Embodiment 1 of the present invention.
FIG. 7 is an explanatory diagram showing the operation of the image forming apparatus according to Embodiment 1 of the present invention.
FIG. 8 is an explanatory view showing the operation of the image forming apparatus according to Embodiment 1 of the present invention.
FIG. 9 is an explanatory view showing the operation of the image forming apparatus according to Embodiment 1 of the present invention.
[Explanation of symbols]
25: intermediate transfer belt (endless belt member), 29: tension steering roll, 50: tension release mechanism, 51, 52: slide plate (slide member), 56, 60: pressure spring (biasing means) 58: swing frame 61, 62: tension release roller (moving means), 63, 64: tension release cam (moving means), 66: first stop position, 67: second stop position.

Claims (4)

In a tension release device for releasing the tension of an endless belt member stretched by a plurality of rolls,
A slide member that slidably supports a roll that applies tension to the endless belt member in a direction in which the tension is loosened; biasing means that biases the slide member in a direction in which tension is applied to the belt member; Moving means for moving the slide member in the direction of loosening the tension, and meandering correction means for correcting meandering of the belt member by tilting one end of the roll that applies tension to the endless belt member ,
The moving means may have a plurality of stop positions for stopping the different positions of the sliding member, and at least one stop position of said moving means, at least one of a predetermined position of the moving means and the meandering correction device The tension releasing device is configured to be able to be fixed to the belt, and configured to restrict the movement of the meandering correction means when the moving means loosens the tension of the belt member . The tension release device according to claim 1 , wherein the movement of the meandering correction means is regulated in conjunction with a movement of the moving means to loosen the tension of the belt member. 3. The tension release mechanism according to claim 2 , wherein the means for regulating the movement of the meandering correction means comprises a guide member for guiding the slide member. In an image forming apparatus provided with a tension release mechanism that forms an image using an endless image carrier belt stretched by a plurality of rolls and releases the tension of the image carrier belt,
The tension release mechanism biases a roll for applying tension to the endless belt member so as to be slidable in a direction in which the tension is loosened, and the slide member in a direction to apply tension to the belt member. A meandering correction that corrects meandering of the belt member by tilting one end portion of a roll that applies tension to the endless belt member, and a moving means that moves the slide member in a direction to loosen the tension. Means and
The moving means may have a plurality of stop positions for stopping the different positions of the sliding member, and at least one stop position of said moving means, at least one of a predetermined position of the moving means and the meandering correction device An image forming apparatus configured to restrict movement of the meandering correction means when the moving means loosens the tension of the belt member .

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