JP2010271380A - Image forming apparatus with endless belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure good cleaning performance through long-term use by reducing damage of a cleaning blade which is caused by a grinding mark when grinding the surfaces of an endless belt and an image carrier. <P>SOLUTION: The endless belt and the image carrier are disposed such that the cleaning blade climbs a gentle slope of the grinding mark which is generated in a periphery direction by grinding, while securing slidability between the cleaning blade, and the endless belt and the image carrier. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus for transferring an image using an endless belt, and more particularly to an image forming apparatus having a cleaning device in the shape of a cleaning blade for cleaning the endless belt.

  Conventionally, in an image forming apparatus such as a copying machine or a laser beam printer, a toner image formed on an image carrier such as a photosensitive drum is transferred onto an intermediate transfer member a plurality of times to form a full color image, And the like that are collectively transferred onto a recording material.

  In particular, a plurality of image carriers that form toner images of the respective colors and an intermediate transfer belt that is an endless belt as an intermediate transfer member are brought into contact with each image carrier, and the toner images are primarily transferred in a superimposed manner before recording. A configuration in which secondary transfer is performed collectively on a material is widely known.

  In the configuration using the intermediate transfer belt, it is necessary to clean the intermediate transfer belt after the toner image is secondarily transferred. The cleaning method includes a fur brush method and a cleaning blade method. The blade cleaning method using a urethane rubber plate cleaning blade is often used as a method having a simple structure and high cleaning effect. Among them, the so-called counter contact method in which the tip of the cleaning blade is in contact with the downstream side of the intermediate transfer belt inclined so as to have an acute angle has good cleaning properties and is frequently used. .

  Further, a sensor comprising a light emitting portion and a light receiving portion is used to output a predetermined pattern on the intermediate transfer belt, and a predetermined pattern portion is determined by a difference between reflected light and the pattern portion on which the toner is applied and the surface of the intermediate transfer belt. There is a density control method in the image forming means by feedback control on the toner replenishment amount and other image forming conditions by detecting the density of the toner, and a position correcting means for correcting the image writing position. When the correction is performed based on the difference in the amount of reflected light between the intermediate transfer belt surface and the pattern portion as described above, the intermediate transfer belt surface shape larger than the pattern portion is required for the reflectance of the intermediate transfer belt surface.

  On the other hand, in order to reduce the contact area generated between the intermediate transfer belt and the cleaning blade and prevent the cleaning blade from curling, a surface shape with a low friction coefficient on the surface of the intermediate transfer belt which is the endless belt is required. It is.

  In such a case, in order to ensure a desired surface shape, a method of polishing using abrasive grains that can easily ensure a desired surface property at low cost is used for surface polishing of an endless belt used in the intermediate transfer belt. Has also been used. As a conventional example, there is Patent Document 1 below.

JP 2003-295481 A

  However, when polishing is performed using abrasive grains as described above, polishing marks are generated on the surface of the endless belt used for the intermediate transfer belt in the moving direction of the intermediate transfer belt.

  The polishing eye holds a gentle slope and a steep slope, and damages the cleaning blade when the steep slope passes through a contact portion (nip) with a cleaning blade that is in counter contact with the intermediate transfer belt. In addition to promoting chipping and wear, when the contact portion of the cleaning blade that is in contact with the counter is caught on the steep slope of the polishing eye and becomes a phenomenon, the contact pressure at the drawn portion is reduced to other parts. Therefore, the phenomenon of drowning will eventually occur.

  In order to solve the above-described problem, a typical configuration of an image forming apparatus according to the present invention includes an image carrier, an endless belt that contacts the image carrier, a tension roller that stretches the endless belt, An urging means for applying a tension force to the tension roller; and a cleaning blade that abuts the endless belt so as to face the tension roller, and the tip of the cleaning blade is downstream of the traveling direction of the endless belt. In an image forming apparatus in which the side is inclined to an acute angle and the above-mentioned cleaning blade is contacted upward, the surface shape of the endless belt is controlled by polishing to Rz: 1 μm or less and Sm: 0.1 mm or less. Cleanin that scrapes off toner while ensuring slipperiness between the cleaning blade and the endless belt Sex is also to ensure at the same time. Further, by providing the endless belt so that the cleaning blade climbs on the gentle slope of the polishing eye generated in the circumferential direction generated by the polishing, the polishing eye generated when the surface of the endless belt is polished is given. This reduces damage to the cleaning blade and ensures good cleaning performance through durability.

  As described above, according to the present invention, in the image forming apparatus that is used by freely controlling the following effects, while ensuring the slipperiness between the cleaning blade, the endless belt and the image carrier, When the endless belt and the image carrier are disposed so that the cleaning blade climbs on the gentle slope of the polishing eye generated in the circumferential direction generated by the polishing, the surfaces of the endless belt and the image carrier are polished. It is possible to reduce the damage of the cleaning blade caused by the generated polishing eyes and to ensure good cleaning performance through durability.

1 is a schematic diagram of an image forming apparatus. Schematic of density sensor. The figure showing the relationship between Sm of an intermediate transfer belt surface, and glossiness. The figure regarding the grinding | polishing member which grind | polishes the surface of an intermediate transfer belt. The figure regarding the grinding | polishing eyes of the intermediate transfer belt surface. FIG. 4 is a diagram illustrating a contact state between an intermediate transfer belt and a cleaning blade. FIG. 3 is a diagram illustrating a contact state between an intermediate transfer belt and a cleaning blade in the present exemplary embodiment. The figure which shows the result of having measured the roughness of the circumferential direction of the surface of the grind | polished intermediate transfer belt.

Example 1
[First embodiment]
A first embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of an image forming apparatus.

  First, the entire image forming apparatus will be described with reference to FIG. The image forming apparatus shown in the figure is an electrophotographic four-color full-color image forming apparatus that forms a full-color image on a transfer material using a photosensitive drum as a plurality of image carriers.

  In FIG. 1, an intermediate transfer belt 2 that travels in the direction of arrow A is disposed inside the image forming apparatus 1. The intermediate transfer belt 2 is configured in an endless belt shape by a dielectric resin such as polyimide resin, polycarbonate, polyethylene terephthalate resin film, polyvinylidene fluoride resin film, and the like, and includes a driving roller 2a, a secondary transfer inner roller 2b, and a tension roller. It is stretched by 2c.

  Here, since the intermediate transfer belt 2 has the largest load at the contact portion with the photosensitive drum 5, it is necessary to dispose the drive roller 2 a on the downstream side of the contact portion with the photosensitive drum 5. If the driving roller 2 a is disposed upstream of the contact portion with the photosensitive drum 5, the intermediate transfer belt 2 is likely to bend, and a larger tension needs to be applied to the intermediate transfer belt 2. This is because the damage of becomes large. For this reason, the tension roller 2c is disposed upstream of the contact portion with the photosensitive drum 5, and the cleaning device 16 for cleaning the intermediate transfer belt 2 is disposed so as to contact the tension roller 2c as a counter roller. .

  The tension roller 2c has a cylindrical shape having a diameter of about Φ21 to 60 mm, and both ends thereof are pressed in the direction of arrow B by springs 2d as urging means, and a tension force is applied to the intermediate transfer belt 2. The applied pressure is about 2 to 3 kg on one side, thereby generating an appropriate tension on the intermediate transfer belt 2.

  Above the intermediate transfer belt 2, four image forming portions Pa, Pb, Pc, and Pd having the same configuration are arranged in series. The configuration will be described using the image forming unit Pa as an example. The image forming portion Pa includes a photosensitive drum 5a that is a drum-shaped image carrier that is rotatably arranged. Around the photosensitive drum 5a, process devices such as a primary charger 6a, a developing device 7a, and a cleaner 8a are arranged. The other image forming units Pb, Pc, and Pd have the same configuration as the image forming unit Pa, and only the photosensitive drums 5b, 5c, and 5d are shown in the drawing. The developing devices 8a to 8d disposed in the image forming units respectively store magenta, cyan, yellow, and black toner images, and each image forming unit forms a toner image of each color.

  First, in the image forming section Pa, an image signal with magenta component colors is projected from the optical means 9a onto the photosensitive drum 5a to form an electrostatic latent image, and magenta toner is supplied from the developing unit to form a magenta toner image. Is done. When the toner image reaches a transfer portion where the photosensitive drum 5a and the intermediate transfer belt 2 come into contact with the rotation of the photosensitive drum 5a, the toner image is transferred onto the intermediate transfer belt 2 by the primary transfer roller 10a. Similarly, the color toner images formed in the image forming portions Pb to Pd are transferred onto the intermediate transfer belt 2 in a superimposed manner.

  On the other hand, the recording material S taken out from the feeding cassette 3 is conveyed to the intermediate transfer belt 2 through the registration roller pair 4. The recording material S is conveyed from the registration roller pair 4 to the nip between the secondary transfer inner roller 2b of the intermediate transfer belt 2 and the secondary transfer roller 11 that is in contact with and away from the intermediate transfer belt 2, and the toner images on the intermediate transfer belt 2 are batched. Then, it is transferred onto the recording material S. The recording material S is conveyed to the fixing unit 13 by the conveying belt 12 and the toner is fixed on the recording material S by heat and pressure. The fixing unit 13 has a mechanism for coating the surface of the fixing roller 13a with releasable oil (for example, silicone oil) in order to improve the releasability between the recording material S and the fixing roller 13a. This oil also adheres. The recording material on which the toner image is fixed is discharged to the discharge tray 14, but when a double-sided image is automatically formed, the recording material passes through a recording material reversal path (not shown) and is fed again to the image forming unit.

  Thereafter, the toner remaining on the photosensitive drums 5a to 5d is removed by the cleaners 7a to 7d. Further, after the residual charges are removed by a pre-exposure means (not shown), the photosensitive drums 5a to 5d are used for the next image formation. The Further, on the downstream side of the secondary transfer portion of the intermediate transfer belt 2, a static elimination charger 15 and a cleaning device 16 are disposed to remove toner and the like attached to the intermediate transfer belt 2.

  As shown in FIG. 1, the cleaning blade 16 a of the cleaning device 16 has the tip thereof inclined with respect to the traveling direction (arrow A direction) of the intermediate transfer belt 2 so that the downstream side has an acute angle. And is pressed against the tension roller 2c by a biasing means (not shown). The cleaning blade 16a is pivotally supported at a substantially central portion in the width direction of the intermediate transfer belt 2 and has an equalizing mechanism.

  Further, in order to perform the density correction means and the image position correction means, as shown in FIG. 2, the density sensor 20 including a light emitting part and a light receiving part is used. The sensor 20 shown in FIG. 2 is arranged toward the intermediate transfer belt in the color image forming apparatus shown in FIG. 1, and measures the density of the toner pattern formed on the surface of the intermediate transfer body 2.

  The sensor 20 includes an infrared light emitting element 51 such as an LED, a light receiving element 52 (52a, 52b) such as a photodiode or Cds, and an IC (not shown) that processes received light data.

  The light receiving element 52 a detects the intensity of irregularly reflected light from the toner pattern 61, and the light receiving element 52 b detects the intensity of regular reflected light from the toner patch 61. By detecting both the regular reflection light intensity and the irregular reflection light intensity, the density of the toner pattern 61 from a high density to a low density can be detected. In addition, the toner pattern density detection detects a predetermined density by the difference between the regular reflection intensity and the irregular reflection intensity on the surface of the intermediate transfer belt and the toner pattern. An optical element such as a lens (not shown) may be used for coupling the light emitting element 51 and the light receiving element 52.

  As described above, by detecting the density of a predetermined toner pattern portion by the density sensor 20, the automatic density correction means in the image forming means is performed by feedback control on the formation conditions such as the toner replenishment amount. For this reason, the surface of the intermediate transfer belt needs the predetermined reflection intensity, and the glossiness of the surface of the intermediate transfer belt needs to be high enough to ensure the predetermined reflection intensity.

  It has been found that the gloss level has a correlation with the surface shape (roughness) of the surface of the intermediate transfer belt.

  FIG. 3 shows the relationship between the glossiness of the surface of the intermediate transfer belt and Sm (average unevenness) as an index of roughness. As can be seen from Fig. 3, when Sm increases (that is, the uneven spacing increases and the surface becomes close to a mirror surface), the glossiness increases, and the glossiness required for the automatic density correction means and automatic position adjustment means is increased. On the contrary, if Sm is small, the glossiness becomes low, and the glossiness necessary for automatic density correction and automatic position correction cannot be secured.

  On the other hand, in order to ensure the slipperiness between the intermediate transfer belt and the cleaning blade, it is necessary to set the glossiness to a predetermined value or less (that is, by setting the glossiness to a predetermined value or less, the Sm is reduced and the intermediate transfer is reduced). The contact area between the cleaning blade and the cleaning blade is increased when the Sm of the belt surface is increased. The frictional force between the cleaning blade and the intermediate transfer belt is increased, which causes the phenomenon of the cleaning blade to bend.

  In addition, when the Sm on the belt surface is small, the contact area between the intermediate transfer belt and the cleaning blade is reduced, so that the adhesion between the intermediate transfer belt and the cleaning blade is reduced, so that the toner recoverability is reduced, and the cleaning failure, etc. There are concerns.

  For the above reasons, in this embodiment, the surface shape of the intermediate transfer belt is Rz: 1 μm or less / Sm: 0.1 mm or less, and the glossiness is maintained at 50% or more (measurement angle 20 °) to 100% or less. Preferably, the surface is polished with abrasive grains to produce the desired surface shape.

  In the polishing method, as shown in FIG. 4, the intermediate transfer belt is placed on the bridging rollers -30a and 30b, and the bridging roller -30b is urged with a predetermined tension in the direction of arrow Y. As a result, the intermediate transfer belt is cross-linked to the cross-linking rollers 30a and 30b with a certain tension.

  The intermediate transfer belt cross-linked to the cross-linking rollers -30a and 30b is rotated in the R direction, and a roll-shaped grindstone 31 is brought into contact with the surface of the intermediate transfer belt so that the grindstone 31 is moved in the R direction or in the opposite direction to the intermediate transfer belt. The surface of the intermediate transfer belt is polished by moving horizontally in the X direction while rotating. In the above embodiment, polishing is performed with a grindstone, but mechanical polishing such as buffing or sandblasting may be employed. A drum-shaped image carrier can be manufactured in the same manner.

  When the surface is polished, a polishing mark 41 as shown in FIG. 5 is formed on the surface of the intermediate transfer belt, and the polishing mark 41 holds the steep slope 42 and the gentle slope 43, and the steep slope 42 is formed as shown in FIG. When the steep slope 42 collides with the cleaning blade 16 against the tip of the cleaning blade 16a in contact with the counter, the tip of the cleaning blade is temporarily pulled in the rotation direction as shown in FIG. 6 due to the collision. By becoming a phenomenon, a part of the drawn-in portion is intensively applied to the other abutting surface, and the frictional force is further increased, resulting in a drowning phenomenon. Similarly, the collision between the tip of the cleaning blade and the steep slope 42 of the polishing eye 41 promotes wear and chipping at the tip of the cleaning blade 16a, and it becomes impossible to ensure good cleaning performance through durability.

  Therefore, in this embodiment, as shown in FIG. 7, the intermediate transfer belt is disposed so that the tip of the cleaning blade 16a hits the gentle slope 43 of the polishing marks 41 on the surface of the intermediate transfer belt.

  Here, FIG. 8 shows a measurement method for judging steep and gentle slopes.

  FIG. 8 shows the result of measuring the roughness of the polished intermediate transfer belt in the circumferential direction. The horizontal axis represents the evaluation length, and the vertical axis represents the shape of the irregularities on the measurement surface in terms of height. Here, as a steep slope, θa is a gentle slope and θb is a steep slope. The condition that the tip of the cleaning blade 16a is provided with the gentle slope 43 is (θa1 + θa2 + θa3... + Θa10) / 10 <(θb1 + θb2 + θb3... + Θb10) / 10.

  By providing the intermediate transfer belt so as to satisfy the above relationship, there is no collision between the polishing eye 41 and the tip of the cleaning blade 16a, so that the phenomenon that the tip of the cleaning blade 16a is drawn as shown in FIG. Phenomena such as chipping and wear can be reduced, and it is possible to provide an image forming apparatus that can secure better cleaning performance than conventional methods with respect to twistability and can also ensure good cleaning performance through durability.

[Second Embodiment]
In the first embodiment, an intermediate transfer belt is used as an endless belt. However, a drum-like shape in which a cleaning blade for cleaning residual toner is in contact with an image carrier such as a photoreceptor on the drum. The present invention is always established in a cleaning apparatus having a configuration in which a cleaning blade is disposed opposite to the image bearing member and the roller portion that applies the belt tension. That is, the present invention can be applied to all cleaning devices such as a photosensitive belt, a transfer belt, and a fixing unit belt.

P Image forming section S Recording material 1 Image forming apparatus 2 Intermediate transfer belt 2a Driving roller 2b Secondary transfer inner roller 2c Tension roller 2d Spring 3 Feed cassette 4 Registration roller pair 5 Photosensitive drum 6 Primary charger 7 Cleaner 8 Developer DESCRIPTION OF SYMBOLS 9 Optical means 10 Primary transfer roller 11 Secondary transfer roller 12 Conveyor belt 13 Fixing part 13a Fixing roller 14 Discharge tray 15 Static elimination charger 16 Cleaning device 16a Cleaning blade 17 Step screw 18 Cushion member 19 Blade support member 20 Concentration sensor 30a / b Bridging roller 31 Grinding wheel 41 Polishing eye 42 Steep slope 21 Slow slope 51 Infrared light emitting element 52 Infrared light receiving element 61 Toner pattern

Claims (6)

  An endless belt as a toner image carrier for holding and transporting a toner image, belt stretching means comprising a plurality of rolls including a driving roll for stretching and transporting the endless belt, and at least one of the bridging rolls In an image forming apparatus provided with a cleaning member that collects residual toner on the endless belt using a counter roll as an opposing roll, an image forming apparatus comprising the endless belt, characterized by having polishing eyes in a circumferential direction of the surface of the endless belt apparatus.   The cleaning member has a cleaning blade that abuts at a counter with respect to the traveling direction of the endless belt, and the cleaning blade abuts on the endless belt with a predetermined pressure by a blade biasing means. The image forming apparatus according to claim 1, wherein:   The polishing marks of the endless belt hold steep and gentle slopes, and the cleaning member is arranged so that the cleaning blade that comes into contact with the counter in the moving direction of the endless belt climbs the gentle slope. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   4. The image forming apparatus according to claim 1, wherein the cleaning blade is in contact with the endless belt with a predetermined pressure by a blade urging unit.   2. The endless belt according to claim 1, wherein the endless belt is made of a material selected from biaxially stretched polyester, polyimide, polyetherimide, nylon, and polypropylene.   2. The endless belt according to claim 1, wherein the surface shape of the endless belt is Rz: 1 μm or less and Sm: 0.1 mm or less in the axial direction.

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