JP5017684B2 - Belt device and image forming apparatus - Google Patents

Description

  The present invention relates to a belt device and an image forming apparatus, and more particularly to a belt shift regulating structure.

As is well known, in an image forming apparatus such as a printer, a copier, a facsimile machine, or a printing machine, an endless belt may be used as a latent image carrier, an image transfer body, or a conveyance member for a recording medium such as a recording sheet. .
It is generally known that the belt is wound around a plurality of rollers and is driven by one of the belts to move in a predetermined direction.

  A belt that is wound around a roller and moves by frictional contact with the roller may meander due to the frictional relationship in the axial direction of the roller or the inclination of the axis. The meandering in this case means that the belt moves while being biased in any one of the width directions of the belt parallel to the axial direction of the roller.

  The image forming apparatus may form a full-color image by superimposing not only a single color but also a plurality of colors. When the belt is used for transferring an image of each color, the belt is formed by meandering of the belt. If the transfer position for the above image changes, an abnormal image such as a color shift occurs.

  Conventionally, as a configuration for preventing meandering of the belt, a block body or the like is integrated at a position close to the end face of the roller on the back surface of the belt, and the position change in the width direction of the belt is regulated by the block body colliding with the end face of the roller. The configuration is known (for example, Patent Document 1).

On the other hand, when a block body is used, a configuration is also proposed in which the belt is prevented from riding on the outer peripheral surface of the roller by pressing the belt (for example, Patent Documents 2, 3, and 4).
As a configuration for preventing the meandering of the belt, a configuration in which a flange or the like is provided on the end surface in the axial direction of the roller instead of providing the above-described block body, and the meandering of the belt by the flange is proposed (for example, a patent) Literature 5, 6).

Japanese Patent No. 3523503 JP 05-204199 A JP 2004-226746 A JP-A-11-161055 Japanese Patent No. 3223771 JP 05-134486 A

In the configuration disclosed in the above patent document, in the configuration in which the meandering of the belt is suppressed using a flange provided on the end surface in the axial direction of the roller, the impact at the time of collision between the block body provided on the back surface of the belt and the end surface of the roller. On the other hand, there are the following problems.
In the configuration in which the end surface of the belt is abutted against the flange, a tension deviation that occurs in the belt in the roller axial direction may occur due to a positional tolerance deviation between the rollers around which the belt is wound or an axial inclination of the roller. Excessive force is generated in the belt width direction. Further, excessive generation of the offset force also occurs when the friction coefficient of the rollers is different in the axial direction.

  If the belt generates excessive shifting force in the width direction, the belt buckles when it hits the flange, and if this state continues for a long period of time, the durability of the belt is impaired. Thus, although it is possible to use a belt having high rigidity in consideration of the durability of the belt, a new problem that causes an increase in cost arises.

  An object of the present invention is to provide a belt device and an image forming apparatus each having a structure capable of preventing the occurrence of abnormal images and durability of the belt with a simple structure without incurring an increase in cost in view of the problems in the conventional belt device. Is to provide.

In order to achieve this object, the present invention has the following configuration.
(1) In a belt device including a belt that is stretched over a plurality of rollers,
An abutting member capable of abutting the end face of the belt against the axial end of the roller;
In the vicinity of the contact position between the abutting member and the belt, a pressing member that suppresses the undulation generated in the belt by pressing from the belt surface in the thickness direction of the belt is provided,
The pressing member is disposed on the upstream side corresponding to the side where the belt starts to contact the peripheral surface of the roller in the running direction of the belt ,
A belt device comprising a rib for locking movement of the pressing member to the downstream side in the belt moving direction at a position downstream of the pressing member in the belt traveling direction .

(2) An image forming apparatus using the belt device according to (1) .

(3) provided with an image carrier that is provided facing the belt and on which a toner image is formed;
The belt is stretched around a plurality of rollers including a driving roller and a tension roller for driving the belt,
The pressing member corresponds to a side where the belt starts to contact the peripheral surface of the tension roller at a position downstream of the driving roller and downstream of the position on the belt facing the image carrier. The image forming apparatus according to (2), wherein the image forming apparatus is provided on an upstream side .

(4) The belt is an intermediate transfer belt on which a toner image on the image carrier is transferred to the surface,
The image according to (3), wherein the toner image transferred onto the intermediate transfer belt is secondarily transferred to a transfer material at a secondary transfer position on the intermediate transfer wound by the driving roller. Forming equipment.

(5) It is provided on the downstream side of the secondary transfer position and on the upstream side of the position facing the image carrier so as to be opposed to the intermediate transfer belt. The image forming apparatus according to (4), further comprising a cleaning unit for cleaning the toner .

(6), wherein the pressing position of the belt by the pressing member used in the belt device is the belt edge surface vicinity which is in contact with the abutment member that is mounted on the roller (2) to ( The image forming apparatus according to any one of 5) .

(7) The image forming apparatus according to any one of (2) to (6) , wherein the pressing member used in the belt device is a sliding member that can contact the belt .

(8) The image forming apparatus according to any one of (2) to (7) , wherein a felt is used on at least a contact surface of the pressing member used in the belt device with the belt .

(9) The pressing member used in the belt device is supported by a non-moving portion provided separately from the roller and the belt , according to any one of (2) to (8) , Image forming apparatus.

(10) The image forming apparatus according to any one of (2) to (9) , wherein the pressing member used in the belt device is provided so as to be able to contact and separate from the belt .

(11) The pressing member used in the belt device is installed integrally with a stationary part capable of supporting the roller, and can be pressed from the belt surface in the thickness direction of the belt ( 2) The image forming apparatus according to any one of (9) .

(12) The pressing member used in the belt device is pressed and urged toward the surface of the belt in the thickness direction of the belt. ( 2) to (11 ) Image forming apparatus.

(13) The image forming apparatus according to any one of ( 2) to (12 ), wherein the pressing member used in the belt device is displaceable in a width direction of the belt .

(14) ( 2) to (13 ), wherein the pressing member used in the belt device is in elastic contact with the belt at a circumferential position of the belt wound around the roller . The image forming apparatus according to any one of the above.

(15) The pressing member used in the belt device is provided straddling between the belt end surface side and a member positioned outside the abutting member with the abutting member interposed therebetween. The image forming apparatus according to any one of ( 2) to (14 ).

(16) The pressing member used in the belt device corresponds to a side opposite to the belt end surface across the abutting member when the roller around which the belt is wound and the abutting member are interlocked. The image forming apparatus according to (15), wherein a part of the belt is supported by a member positioned outside the abutting member and is in contact with the surface of the belt.

(17) The pressing member used in the belt device may be partially supported by the abutting member when the abutting member is fixed to a roller around which the belt is wound. The image forming apparatus according to (15), wherein the image forming apparatus is in contact with the surface of the image forming apparatus.

(18) A toner mark detection sensor mounting portion for detecting a toner mark formed on the belt is provided in the vicinity of the roller, and the pressing member is supported by the toner mark detection sensor mounting portion. The image forming apparatus according to any one of ( 2 ) to (17).

(19) The image forming apparatus according to (18), wherein the toner mark detection sensor mounting portion is displaceable along a width direction of the belt.

(20) The image forming apparatus according to any one of (2) to (17) , wherein the pressing member used in the belt device is disposed in a non-image area in a width direction of the belt .

  (21) A toner mark detection sensor mounting portion is provided in the vicinity of the roller, and the toner mark detection sensor mounting portion is provided with a pressing member that presses the vicinity of the belt end surface from the surface side. (20) The image forming apparatus according to (20).

  According to the present invention, in the case of using a configuration in which the deviation of the belt end surface by the abutting member is used, buckling that occurs when the belt end surface abuts against the abutting member is suppressed by the pressing member. As a result, it is possible to reliably prevent the deterioration of the durability of the belt and the positional deviation between the images when buckling deformation occurs. In particular, since the pressing member is configured to positively press the surface near the belt end face that hits the abutting member, unlike the case where the lifting is suppressed, which is a phenomenon in which a gap is formed between the belt and the roller surface. Occurrence of the undulation itself, in other words, deformation of the belt can be prevented and the occurrence of buckling deformation can be reliably prevented.

  In addition, as a configuration for preventing buckling of the belt, a simple configuration that only requires a pressing member is sufficient, so that the durability of the belt is improved without causing an increase in cost due to the high rigidity of the belt, and color misregistration, etc. It is possible to prevent the occurrence of abnormal images.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic diagram showing an image forming apparatus using a belt device according to the present invention. The image forming apparatus shown in FIG. 1 uses a belt as a transfer member to superimpose a plurality of color images on the belt. And a configuration for forming a full-color image.

In FIG. 1, reference numeral 1 denotes a cylindrical photosensitive drum set to φ24 corresponding to a latent image carrier, and the photosensitive drum 1 rotates at a peripheral speed of 120 mm / s.
A roller-shaped charger 2 serving as charging means is pressed against the surface of the photosensitive drum 1 so that the photosensitive drum 1 can be driven and rotated by the rotation of the photosensitive member 1.
In the charger 2, the photosensitive drum 1 is uniformly charged to a surface potential of −500 V by applying a DC or a bias in which AC is superimposed on DC from a high voltage power source (not shown).

After charging, the photosensitive drum 1 is exposed to image information by an exposure unit 3 which is a latent image forming unit, and an electrostatic latent image is formed.
This exposure process is performed by a laser beam scanner or LED using a laser diode.

  In FIG. 1, reference numeral 4 denotes a one-component contact developing device as developing means, which visualizes the electrostatic latent image on the photosensitive drum 1 as a toner image by a predetermined developing bias supplied from a high voltage power source (not shown). . In this embodiment, the developing device 4 stores 180 g of one-component toner at an initial stage. Note that the developing device may be a two-component developing device or a non-contact developing device.

In FIG. 1, reference numeral 10 indicates a process unit in which the photosensitive drum 1, the charger 2 and the developing device 4 are integrated.
Four process units 10 are arranged in parallel. When a full-color image is formed, a visible image is formed in each process unit 10 in the order of black, yellow, magenta, and cyan. A full-color image is formed by sequentially transferring images onto the intermediate transfer belt 15 in contact with the drum 1.

The intermediate transfer belt 15 is stretched around a drive / secondary transfer counter roller 21 (described later), a metal cleaning counter roller 16, a primary transfer roller 5 (described later), and a tension roller 20 (described later). It is driven to rotate through a drive roller 21 by a drive motor (not shown). In order to apply the belt tension, the tension roller 20 is provided with an elastic body such as a spring (not shown) on both sides in the axial direction, and this elastic body applies an elastic force in the direction in which the intermediate transfer belt 15 is stretched. Has been granted.
The tension roller 20 has an aluminum pipe shape of φ19 and a width of 231 mm. As shown in FIGS. 2 and 3, a flange 26 corresponding to an abutting member of φ22 having a diameter larger than the outer diameter of the roller at both ends. Is press-fitted. The flange 26 functions as a regulating member that regulates the meandering of the intermediate transfer belt 15 when the end face in the width direction of the intermediate transfer belt 15 abuts. The conveyance direction of the intermediate transfer belt 15 is the direction of the arrow in FIG.

  As the driving roller 21, polyurethane rubber (thickness: 0.3 to 1 mm), thin layer coating roller (thickness: 0.03 to 0.1 mm), etc. can be used. A small urethane coating roller (thickness 0.05, φ19) is used.

As the primary transfer member 5, a conductive blade, a conductive sponge roller, a metal roller, or the like can be used. In this embodiment, a φ8 metal roller is used, and 8 mm in the moving direction of the intermediate transfer belt 15 with respect to the photoreceptor 1. 1 mm offset in the vertical upward direction.
A predetermined transfer bias +500 to +1000 V is commonly applied to the primary transfer roller 5 facing the photosensitive drum 1 across the intermediate transfer belt 15 by a single high-voltage power supply (not shown) via the intermediate transfer belt 15. A transfer electric field is formed, and the toner image on the photosensitive drum 1 is electrostatically transferred to the intermediate transfer belt 15.

  The image forming apparatus shown in FIG. 1 is provided with a toner mark detection sensor 17 for detecting a toner mark formed on the intermediate transfer belt 15 and measuring the toner density and each color transfer position. The toner mark detection sensor 17 is constituted by a regular reflection type or diffusion type optical sensor provided in a toner mark detection sensor mounting portion 17A disposed in the vicinity of the tension roller 20, and image density and color are determined according to the detection result. It is used for feedback control of alignment (position alignment).

In FIG. 1, reference numeral 32 denotes an intermediate transfer belt cleaning unit, which has a function of cleaning by scraping off transfer residual toner on the intermediate transfer belt 15 with a cleaning blade 31.
As a cleaning blade material, urethane rubber having a thickness of 1.5 to 3 mm and a rubber hardness of 65 to 80 ° is used, and is brought into counter contact with the intermediate transfer belt 15. The transfer residual toner thus scraped off is stored in the intermediate transfer member waste toner storage section 33 through a toner conveyance path (not shown).

  At least one of the portion corresponding to the cleaning nip portion of the intermediate transfer belt 15 or the edge portion of the cleaning blade 31 is coated with a coating agent such as a lubricant, toner, zinc stearate at the time of assembly. In addition to preventing the blade from rolling up, a dam layer is formed in the cleaning nip to improve the cleaning performance.

Each roller that stretches the intermediate transfer belt 15 is supported from both sides of the intermediate transfer belt 15 by an intermediate transfer belt unit side plate (not shown).
Materials used for the intermediate transfer belt 15 include PVDF (vinylidene fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PI (polyimide), PC (polycarbonate), TPE (thermoplastic elastomer), and carbon black. A resin film-like endless belt is used in which a conductive material such as a resin film is dispersed. In this example, a thickness of 90 to 90 is formed with a single layer structure in which carbon black is added to TPE having a tensile modulus of 1000 to 2000 MPa. A belt having a width of 160 μm and a width of 230 mm is used.

In addition, the resistance of the intermediate transfer belt 15 is a volume resistivity of 10 ⁸ to 10 ¹¹ Ω · cm and a surface resistivity of 10 ⁸ to 10 ¹¹ Ω / □ in an environment of 23 ° C. and 50% RH. -Measured at HT450, preferably applied voltage 500 V, application time 10 seconds.

  When the volume resistivity and surface resistivity of the intermediate transfer belt 15 exceed the above-described ranges, the intermediate transfer belt 15 is charged. Therefore, it is necessary to take a measure such as setting the set voltage value higher as it goes downstream in the image forming order. Therefore, it becomes difficult to use a single power supply for the primary transfer unit. This is because the charge generated on the surface of the intermediate transfer belt 15 is increased due to the discharge generated in the transfer process, the transfer material peeling process, and the like, and self-discharge becomes difficult. Need arises. Also, if the volume resistivity and surface resistivity are below the above ranges, the charge potential decays quickly, which is advantageous for static elimination by self-discharge, but toner scatter occurs because the current during transfer flows in the surface direction. End up. Therefore, the volume resistivity and the surface resistivity of the intermediate transfer belt 15 in the present invention are within the above ranges.

In FIG. 1, reference numeral 25 denotes a secondary transfer roller.
The secondary transfer roller 25 is configured to have a diameter of 19 mm and a width of 222 mm by covering a metal core such as SUS of φ6 with an elastic body such as urethane adjusted to a resistance value of 10 ⁶ to 10 ¹⁰ Ω by a conductive material. Has been. As the material, an ion conductive roller (urethane + carbon dispersion, NBR, hydrin), an electronic conductive type roller (EPDM) or the like is used. In this embodiment, a urethane roller having a diameter of 19 and an Asker C hardness of 35 to 50 °. Was used. Here, if the resistance value of the secondary transfer roller 25 exceeds the above range, it becomes difficult for the current to flow. Therefore, a higher voltage must be applied in order to obtain the required transfer property, resulting in an increase in power supply cost. . In addition, since it is necessary to apply a high voltage, discharge occurs in the gap before and after the nip of the transfer portion, and white spots are lost on the halftone image due to the discharge. This is remarkable in a low-temperature and low-humidity environment (for example, 10 ° C. and 15% RH). On the other hand, if the resistance value of the secondary transfer roller 25 falls below the above range, the transferability between the multi-color image portion (for example, three-color superimposed image) and the single-color image portion existing on the same image cannot be achieved. This is because the resistance value of the secondary transfer roller 25 is low, so that a sufficient current flows to transfer the monochrome image portion at a relatively low voltage. However, it is optimal for the monochrome image portion to transfer the multiple color image portion. This is because a voltage value higher than the voltage is required, and setting a voltage that can transfer a plurality of color image portions causes an excessive transfer current in a single color image, resulting in a decrease in transfer efficiency.

  The resistance value of the secondary transfer roller 25 is measured by installing the roller 25 on a conductive metal plate and applying a load of 4.9 N on one side to both ends of the core metal and the metal core and the metal. It calculated from the electric current value which flows when a voltage of 1 kV is applied between the plates.

  A transfer material 22 such as a sheet stacked in a storage unit such as a paper feed cassette is a timing at which the front end of the toner image on the surface of the intermediate transfer belt 15 reaches the secondary transfer position by a paper feed conveyance roller 23 and a registration roller pair 24 The toner image on the intermediate transfer belt 15 is transferred to the transfer material 22 by applying a predetermined transfer bias by a high voltage power source (not shown). In the image forming apparatus according to the present exemplary embodiment, a vertical path is used as the sheet feeding path. The transfer material 22 is separated from the intermediate transfer belt 15 by the curvature of the secondary transfer counter roller 21, and the toner image transferred to the transfer material 22 is fixed by the fixing unit 40 and then discharged.

Further, in this embodiment, the process speed at the time of fixing is changed depending on the type of the transfer material 22. Specifically, when a transfer material having a basis weight of 100 g / m ² or more is used, the process speed is set to half speed, and the transfer material is twice the normal process speed in the fixing nip formed by the fixing roller pair. The toner image fixing property can be secured by passing through the time.

  In the image forming apparatus having the above-described configuration, meandering is suppressed when the intermediate transfer belt 15 abuts the end face in the width direction by the flange portion 26 provided on the tension roller 20. However, in this embodiment, a configuration is provided that suppresses buckling deformation of the intermediate transfer belt 15 that occurs when the end face is abutted for the reason described above.

Hereinafter, this configuration will be described.
FIG. 4 is a schematic diagram for explaining the principle of the buckling deformation preventing structure of the intermediate transfer belt 15. In the drawing, in the vicinity of the contact position between the flange 26 provided on the tension roller 20 and the intermediate transfer belt 15, the surface of the intermediate transfer belt 15 in the thickness direction of the intermediate transfer belt 15 (the surface in this case is photosensitive). A pressing member 50 </ b> A is provided via a holder 51 that presses this from the side facing the body 1 and suppresses the undulation generated in the intermediate transfer belt 15.
The pressing member 50A is located outside the image forming region in the width direction of the intermediate transfer belt 20 parallel to the axial direction of the tension roller 20, and particularly in the vicinity of the end face of the intermediate transfer belt 15 that contacts the flange 26 corresponding to the abutting member. It is arranged to be a position where can be pressed.
The pressing member 50A is a member that can slide so as not to resist the movement of the intermediate transfer belt 20 when the surface of the intermediate transfer belt 20 is pressed. Dynamic POM, sliding ABS, sliding sponge, felt material, etc. are used. As for the size of the pressing surface of the pressing member 50A in the width direction of the intermediate transfer belt 20, it is necessary to secure an A4 paper horizontal size of 210 mm and a letter paper horizontal size of 216 mm or more as an image area on the intermediate transfer belt 15. Therefore, the lateral width of the pressing member 50A is set to 2 to 5 mm.

  As shown in FIG. 5, the pressing member 50 </ b> A that presses the intermediate transfer belt 15 while facing the tension roller 20 with the intermediate transfer belt 15 interposed therebetween, as shown in FIG. 5, the tension roller 20 around which the intermediate transfer belt 15 is wound around. The intermediate transfer belt 15 is disposed on the upstream side corresponding to the side where the intermediate transfer belt 15 starts to contact the circumferential surface in the rotational direction. As a result, the pressing member 50A is positioned on the pulling side where tension is generated with respect to the intermediate transfer belt 15, and buckling deformation is performed on the stretched surface side where buckling deformation is likely to occur when an external force called tension is applied. Makes it easier to prevent the occurrence of

  FIG. 6 is a view showing a modification of the pressing member, and the pressing member (indicated by reference numeral 50B for the sake of convenience) shown in FIG. 6 is composed of a roller that can be interlocked while pressing the intermediate transfer belt 15. The pressing member 50 </ b> B can be rotated by inserting a rotating shaft 51 </ b> A that is rotatably supported by the holder 51, and rotates in conjunction with the movement of the intermediate transfer belt 15. In this embodiment, the pressing member 50 </ b> B composed of a roller uses, as a material, a sliding POM, a sliding ABS, or the like that is a highly slidable material that does not inhibit the movement of the intermediate transfer belt 15. The contact width is 2 to 5 mm.

  FIG. 7 is a view showing still another modified example of the pressing member, and the pressing member shown in FIG. 7 (indicated by reference numeral 50C for convenience) is rotatably supported by a holder 51 ′. A pressure is applied toward the surface of the intermediate transfer belt 15 by an elastic body 52 such as a spring to be pressed. The pressing member 50 </ b> C uses sliding POM, sliding ABS, etc., which are highly slidable materials, and has a lateral width of 2 to 5 mm, and is 1 to the intermediate transfer belt 15 by the elastic body 52. -10N.

  Since the present embodiment is configured as described above, the intermediate transfer belt 15 can be pressed from the surface side in the thickness direction near the end of the intermediate transfer belt 15 that abuts against the flange portion 26 of the tension roller 20. By providing the member, it is possible to prevent buckling deformation from occurring in the intermediate transfer belt 15 that abuts against the flange portion 26. In particular, the pressing member does not restrict the generation of a gap due to the floating of the intermediate transfer belt 15 but suppresses the behavior of the intermediate transfer belt 15 in the width direction by suppressing the behavior of buckling deformation including the floating. Thus, stress concentration of the intermediate transfer belt 15 can be prevented and deterioration of durability can be prevented.

  The pressing member is configured to allow the belt to slide so as not to hinder the movement of the intermediate transfer belt 15 when contacting and pressurizing the intermediate transfer belt 15, so that the lifting of the belt is simply restricted. In addition, unlike the case of pressing, it is possible to prevent the movement of the intermediate transfer belt 15 from changing to prevent the image transfer position from changing, and to prevent the occurrence of abnormal images such as color misregistration.

Next, a modification of the main part in the above embodiment will be described.
FIG. 8 is a diagram illustrating a configuration related to the installation structure of the pressing member. In the configuration illustrated in FIG. 8, the pressing member 500 is supported by a stationary portion 501 provided separately from the tension roller 20 and the intermediate transfer belt 15. ing.
As the non-moving portion, a side plate of the image forming apparatus main body is selected, and the pressing member 500 described above is installed in an integrated structure with holder members 500A attached to both sides or one side of the intermediate transfer belt 15 in the width direction.

  The configuration of the pressing member 500 in this configuration, that is, the arrangement position and the arrangement dimension with respect to the intermediate transfer belt 15 are the same as those in the embodiments shown in FIGS.

  As shown in FIG. 9, the holder member 500 </ b> A provided in the non-moving portion 501 is attached to and detached from the non-moving portion 501, in other words, the pressing member 500 is provided so as to be able to contact and separate from the intermediate transfer belt 15. It is also possible to make it convenient to replace the holding member 500 due to wear or the like. As a result, only the part to be exchanged can be removed, so that an increase in cost can be prevented by minimizing the addition of a new part. As shown in FIG. 10, the holder member 500 </ b> A does not dare to be a separate member from the pressing member 500, but has a structure that extends from the immovable portion 501 and presses the surface of the intermediate transfer belt 15. Is also possible. Thereby, a cost rise can be avoided by comprising a support part and a pressing member by the same member.

  FIG. 11 shows a configuration for applying a pressing force to the pressing member 500. In FIG. 11, reference numeral 502 is disposed between the holder member 500A integrated with the immovable portion 501 and the pressing member 500. An elastic body such as a spring is shown. In this configuration, since the pressing member 500 can be displaced in the thickness direction of the intermediate transfer belt 15 and the shape restoring force of the elastic body can be used, the intermediate transfer belt due to the eccentricity of the tension roller 20 or the like. Since the pressing member 500 can always be pressed against the surface of the intermediate transfer belt 15 regardless of the change in the gap between the surface of the pressing member 500 and the pressing member 500, the buckling deformation that is to occur in the intermediate transfer belt 15 is suppressed. be able to.

On the other hand, FIG. 12 shows a modification of the structure for applying the urging force to the pressing member 500. In FIG. 12, the direction perpendicular to the thickness direction of the intermediate transfer belt 15, in other words, the axis of the tension roller 20 is shown. An elastic body 502 that can expand and contract along the direction is connected to the pressing member 500. Thereby, for example, even when the tension roller 20 is displaced in the axial direction, the pressing member 500 can be always pressed near the flange 26 using the elastic restoring force of the elastic body 502.
The case where the axial displacement of the tension roller 20 occurs corresponds to the case where the tension roller 20 is a rotating member and the support portion 20A of the tension roller 20 positioned outside the flange 26 is stationary. ing. In this case, a slight gap is provided between the flange 26 of the tension roller 20 and the support portion 20A so as not to rub against each other. For this reason, when an external force due to meandering of the intermediate transfer belt 15 acts on the tension roller 20, the tension roller 20 may be displaced in the axial direction. Therefore, even when the flange 26 of the tension roller is displaced in the axial direction, the pressing member 500 is always positioned at the same position, that is, where buckling is likely to occur, by following and displacing the pressing member 500 by elastic or other biasing. Thus, occurrence of buckling deformation of the intermediate transfer belt 15 is prevented.

  FIG. 13 is a view showing a modification of the arrangement configuration of the pressing member. In FIG. 13, the pressing member 505 is an intermediate transfer belt by the elastic body 502 at the circumferential position of the intermediate transfer belt 15 that is wound around the tension roller 20. By pressing the surface of 15, the elastic contact is made. As a result, even when the axial center position is changed in order for the tension roller 20 to stably apply the tension to the intermediate transfer belt 15, buckling deformation is always performed in response to the position change of the intermediate transfer belt 15. It is designed to depress buckling deformation by pressing an easily occurring location.

  FIG. 14 is a diagram illustrating a partial modification of the configuration illustrated in FIG. 5, in which the pressing member 50 </ b> A is not elastically moved through the elastic body 502, not the stationary portion like the holder member 51. The support structure is capable of contacting the belt 15. Accordingly, as in the case of the configuration shown in FIG. 5, buckling deformation can be prevented for a position where buckling deformation easily occurs due to an external force called tension, and the change in the axial center position of the tension roller 20 can be followed. Thus, the pressing action can be maintained.

  FIG. 15 is a diagram showing a configuration in which the material used for the pressing member 50A is changed on the premise of the configuration shown in FIG. 14. In FIG. 15, the holder member 500A provided on the immovable portion 501 and the pressing member are shown. On the surface of the pressing member 50A that is elastically pressed against the belt surface by the elastic body 502 disposed between the member 50A, that is, the contact portion with the belt surface (the portion indicated by reference numeral 50A1 in FIG. 15) A sliding sponge or felt that can be slid so as not to hinder the movement of the intermediate transfer belt 15 is disposed. Thereby, the increase in sliding resistance can be suppressed and damage to the belt end face that is turning right with the pressing member 50A can be prevented.

  FIG. 16 is a view showing a modification of the supporting structure of the pressing member 50C when the pressing member 50C is configured by a roller for the configuration shown in FIG. 7. In FIG. The reference numeral 51 ′ used in FIG. 5 is suspended and supported by the non-moving portion 501 via an elastic body 52 (also indicated by reference numeral 52). In this case, the holder 51 ′ is provided so as to be able to move up and down, and the habit of the direction in which the pressing member 50 C is always pressed against the surface of the intermediate transfer belt 15 by the urging of the elastic body 52, the direction in which it is lowered in the drawing. Is granted. Accordingly, as in the case shown in FIG. 7, there is no portion that rubs against the surface of the intermediate transfer belt 15, so that deterioration of the intermediate transfer belt 15 can be prevented.

  FIG. 17 is a view showing a modification of the main structure of the pressing member shown in FIG. 14. In FIG. 17, the pressing member (indicated by reference numeral 50A used in FIG. 14 for convenience) is the intermediate transfer belt 15. The surface on the downstream side of the position in contact with the intermediate transfer belt 15 in the rotation direction of the tension roller 20 wound around the circumferential surface is locked by a rib 50A1 extending vertically. As a result, the pressing member 50A in contact with the surface of the intermediate transfer belt 15 is prevented from being dragged by the movement of the intermediate transfer belt 15 and changing the contact position with the belt by the locking of the rib 50A1. The pressing position of the pressing member 50A against the intermediate transfer belt 15 is prevented from being changed, and a portion where buckling deformation is likely to occur is always pressed to prevent the occurrence of buckling.

On the other hand, FIG. 18 is a schematic diagram for explaining the operation when the pressing member is provided in the non-moving portion. In FIG. 1, the intermediate transfer belt 15 is accommodated in a unit TU including a support portion 200 of the tension roller 20 and is provided so as to be detachable from the image forming apparatus.
When the pressing member 500 is provided on the non-moving portion 501 for this configuration, the pressing member 500 is positioned on the non-moving portion 501 regardless of the movement of the unit TU, and as shown in FIG. In addition, there is no interference with the process unit 10 when the unit TU is pulled out.

On the other hand, when the pressing member 500 is installed on the tension roller support portion 200 on the unit TU side, as shown in FIG. 19C, the relationship is linked to the movement of the unit TU. The unit TU cannot be taken out. As described above, it is desirable that the pressing member 500 be installed in a stationary part different from the unit TU provided with the intermediate transfer belt 15, the tension roller 20, and the support part.
In the configuration shown in FIG. 19, as a method for avoiding interference with the process unit 10 when the unit TU is inserted / removed, the order of the unit TU can be set after the process unit 10 is pulled out, Using a path that does not interfere with the process unit 10, for example, a path that is pulled out after moving below the process unit 10, the process unit 10 is opened in a state where it is positioned below the process unit 10 in the reverse order of the pull-out. There is a method of setting a procedure for raising the position from the position to the normal position and positioning the unit TU in a direction perpendicular to the paper surface.

Next, the modification regarding the support structure of a pressing member is demonstrated.
FIG. 20 shows a structure in which the pressing member 50A is supported by a stationary part other than the tension roller 20 and the intermediate transfer belt 15 which are movable parts. In FIG. A part of the pressing member 50 is attached to a tension roller bearing 53 that faces the end face of the intermediate transfer belt 15 across the corresponding flange 26 and is located outside the flange 26. Accordingly, the pressing member 50A is configured to reach the surface of the intermediate transfer belt 15 from the tension roller bearing 53 in a state where the holder 51 straddles the flange 26, and presses the belt surface.

  FIG. 21 differs from FIG. 20 in that the holder 51 of the pressing member 50 </ b> A straddles the flange 26 and covers the intermediate transfer belt for a configuration in which the rotation shaft of the tension roller 20 is supported by the side plate 503 corresponding to the non-moving portion. 15 shows a state in which a part is attached to and supported by the side plate 503 from the surface 15.

  FIG. 22 shows a configuration for the case where the tension roller 20 is not linked to the flange 26 corresponding to the abutment member, in other words, the case where the flange 26 is fixed. A member 50 </ b> A is attached to the flange 26 with a part of the holder 51.

  In the configuration as described above, the pressing member 50A is installed near the place where the pressing member is required to be pressed, that is, in the vicinity of the position where the end surface of the intermediate transfer belt 15 is likely to be buckled. Therefore, it can be configured as an assembly in a unit that accommodates the tension roller and the intermediate transfer belt.

On the other hand, as a supporting structure of the pressing member, it can be provided according to the form of the above-described immovable portion, and this configuration will be described below.
FIG. 23 is a diagram showing a configuration of a toner mark detection sensor mounting portion denoted by reference numeral 17 in FIG. 1. In FIG. 23, the toner mark detection sensor 17 is a part of the toner mark detection sensor mounting portion 170 and is an intermediate transfer. The toner mark TM formed on the belt 15 is attached at a position where it can be optically detected.
In this embodiment, a pressing member is attached to the toner mark detection sensor attachment portion 170.
FIG. 24 is a diagram showing one mounting structure of the pressing member. In FIG. 24, the tension roller 20 is provided near the both ends in the axial direction of the tension roller 20 in the toner mark detection sensor mounting portion 170, although not shown. A pressing member 50 </ b> A is provided via a holder 51 at a position corresponding to the vicinity of the end face of the belt 15 that abuts the flange.

  In the toner mark detection sensor mounting portion 170, both end surfaces along the axial direction of the tension roller 20 are pressed and urged by an elastic body 501 such as a spring, and the position of the pressing member 50A that presses the surface of the intermediate transfer belt 15 is the tension. The state which does not change in the axial direction of the roller 20 is maintained.

On the other hand, FIG. 25 shows a configuration in which the installation position of the pressing member 50A and the toner mark detection sensor mounting portion 170 can be adjusted. In FIG. A long groove 170A parallel to the axial direction of the tension roller 20 is formed.
The pressing member 50A is integrated with the long groove 170A by fitting the holder 51, and the intermediate transfer belt 15 is buckled by moving the holder 51 in the long groove 170A. It can be positioned at an easy position. As a result, even if the processing accuracy is somewhat poor, the positional relationship between the pressing member 50A attached to the apparatus and the intermediate transfer belt 15 pressed by the pressing member is optimized so that buckling of the intermediate transfer belt 15 is likely to occur. The occurrence of buckling can be suppressed.

  In such a configuration, even when the toner mark detection sensor mounting portion 170 is unitized, a pressing member can be provided for the unit.

The pressing member is not only configured to have a sliding relationship with respect to the surface of the intermediate transfer belt 15, but similarly to the configuration shown in FIG. 4 or FIG. Of course it is possible.
Note that the belt can be not only the above-described intermediate transfer member but also a latent image carrier such as a photosensitive member or a belt for transferring a transfer material.

1 is a schematic diagram of an image forming apparatus using a belt device according to an embodiment of the present invention. It is a figure for demonstrating the meandering control structure of the belt in the belt apparatus by the Example of this invention. It is a front view of the belt meandering control structure in the belt device in the embodiment of the present invention. It is a schematic diagram for demonstrating the principle structure which concerns on buckling suppression in the belt apparatus by this invention Example. It is a figure for demonstrating the arrangement configuration of the pressing member in the structure shown in FIG. It is a figure for demonstrating the modification of the pressing member shown in FIG. It is a figure for demonstrating a partial modification to the structure shown in FIG. It is a figure which shows an example of the support structure of the pressing member used for the belt apparatus by the Example of this invention. It is a figure which shows the partial modification of the structure shown in FIG. It is a figure which shows the other modification of a part of structure shown in FIG. It is a figure which shows the partial modification of the structure shown in FIG. It is a figure which shows the partial modification of the structure shown in FIG. It is a figure which shows the modification of the principal part structure of the pressing member shown in FIG. It is a figure which shows the partial modification of the structure shown in FIG. It is a figure which shows the modification of the pressing member used for the structure shown in FIG. It is a figure which shows the partial modification of the structure shown in FIG. It is a figure which shows the some modification of the structure shown in FIG. It is a figure for demonstrating the effect | action of the pressing member in the structure shown in FIG. It is a figure for demonstrating an effect | action at the time of using the pressing member of a structure different from the structure shown in FIG. It is a figure which shows one of the support structures of the pressing member used for the structure shown in FIG. FIG. 21 is a diagram illustrating a partial modification of the configuration illustrated in FIG. 20. It is a figure which shows the other modification of a part of structure shown in FIG. It is a figure which shows the modification of the installation structure of the pressing member used for the structure shown in FIG. It is a front view of the structure shown in FIG. FIG. 25 is a diagram illustrating a partial modification of the configuration illustrated in FIG. 24.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Process cartridge 15 Intermediate transfer belt 17 Toner mark detection sensor 20 Tension roller 26 Flange 50A, 50B, 500, 505 Holding member 50A1 Rib as a locking part 50C Roller 51,500A Holder 170 Toner mark detection sensor attachment part 501 Non-moving part 502 Elastic body

Claims (21)

In a belt device including a belt that is stretched around a plurality of rollers,
An abutting member capable of abutting the end face of the belt against the axial end of the roller;
In the vicinity of the contact position between the abutting member and the belt, a pressing member that suppresses the undulation generated in the belt by pressing from the belt surface in the thickness direction of the belt is provided,
The pressing member is disposed on the upstream side corresponding to the side where the belt starts to contact the peripheral surface of the roller in the running direction of the belt ,
A belt device comprising a rib for locking movement of the pressing member to the downstream side in the belt moving direction at a position downstream of the pressing member in the belt traveling direction . An image forming apparatus using the belt device according to claim 1 . An image carrier that is provided facing the belt and on which a toner image is formed;
The belt is stretched around a plurality of rollers including a driving roller and a tension roller for driving the belt,
The pressing member corresponds to a side where the belt starts to contact the peripheral surface of the tension roller at a position downstream of the driving roller and downstream of the position on the belt facing the image carrier. The image forming apparatus according to claim 2, wherein the image forming apparatus is provided on an upstream side . The belt is an intermediate transfer belt on which a toner image on the image carrier is transferred to the surface,
4. The image according to claim 3, wherein the toner image transferred onto the intermediate transfer belt is secondarily transferred to a transfer material at a secondary transfer position on the intermediate transfer wound by the driving roller. Forming equipment. It is provided on the downstream side of the secondary transfer position and on the upstream side of the position facing the image carrier so as to face the intermediate transfer belt, and cleans transfer residual toner on the intermediate transfer belt. The image forming apparatus according to claim 4, further comprising a cleaning unit configured to perform cleaning . To any one of claims 2 to 5, characterized in that said pressing the belt edge surface vicinity of the pressing position of the belt by the member is in contact with the abutment member being mounted on said roller for use in the belt device The image forming apparatus described. The image forming apparatus according to claim 2, wherein the pressing member used in the belt device is a sliding member that can contact the belt . The image forming apparatus according to claim 2, wherein a felt is used on at least a contact surface of the pressing member used in the belt device with the belt . 9. The image forming apparatus according to claim 2 , wherein the pressing member used in the belt device is supported by a non-moving portion provided separately from the roller and the belt . The image forming apparatus according to claim 2 , wherein the pressing member used in the belt device is provided so as to be able to contact and separate from the belt . The pressing member used in the belt device, 2 through claim, characterized in that installed integrally with the support capable immovable portion of the roller can be pressed from the belt surface in the thickness direction of the belt The image forming apparatus according to claim 9 . 12. The image forming apparatus according to claim 2 , wherein a pressing member used in the belt device is pressed and urged toward the surface of the belt in a thickness direction of the belt . The image forming apparatus according to claim 2 , wherein the pressing member used in the belt device is displaceable in a width direction of the belt . Wherein the pressing member used in the belt device, according to any one of claims 2 to 13, characterized in that it the belt orbital position of the belt which is wound around the rollers resiliently contacting Image forming apparatus. The presser member used in the belt device is provided across a belt end surface side and a member located outside the abutting member with the abutting member interposed therebetween. The image forming apparatus according to any one of 2 to 14 . The pressing member used in the belt device is an abutting member corresponding to the opposite side of the belt end surface across the abutting member when the roller on which the belt is wound and the abutting member are interlocked. The image forming apparatus according to claim 15, wherein a part of the belt is supported by a member located outside the belt and is in contact with the surface of the belt. The pressing member used in the belt device is partially supported by the abutting member and fixed to the surface of the belt when the abutting member is fixed to a roller around which the belt is wound. The image forming apparatus according to claim 15, wherein the image forming apparatus is in contact. A toner mark detection sensor mounting portion for detecting a toner mark formed on the belt is provided in the vicinity of the roller, and the pressing member is supported by the toner mark detection sensor mounting portion. Item 18. The image forming apparatus according to any one of Items 2 to 17. The image forming apparatus according to claim 18, wherein the toner mark detection sensor mounting portion is displaceable along a width direction of the belt. The image forming apparatus according to claim 2 , wherein the pressing member used in the belt device is disposed in a non-image area in a width direction of the belt .   21. A toner mark detection sensor mounting portion in the vicinity of the roller, wherein the toner mark detection sensor mounting portion is provided with a pressing member that presses the vicinity of the belt end surface from the surface side. The image forming apparatus described in 1.

Images