JP2012155253A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that prevents poor cleaning including passing of toner through a cleaning device.SOLUTION: An image forming apparatus includes a scraper that scrapes attached substances on a belt-shaped image carrier 6. The scraper 10 comes into pressure-contact with the image carrier between a plurality of belt support members for supporting the image carrier.

Description

  The present invention relates to an image forming apparatus that forms an image by an electrophotographic process.

  As is well known, in an image forming apparatus that forms an image by an electrophotographic process, a toner image is formed on an image carrier by charging, exposure and development, and the transferred toner image is transferred to a recording material. An image fixing type, a toner image is formed on an image carrier by charging, exposure and development, the formed toner image is transferred to an intermediate transfer member, and the toner image on the intermediate transfer member is further transferred to a recording material. There is a type that fixes a toner image transferred to a recording material.

  These types of image forming apparatuses include a cleaning device that cleans an image bearing member such as a photosensitive member or an intermediate transfer member after transfer of a toner image.

  By cleaning with a cleaning device, a toner image can be repeatedly formed on an image carrier such as a photosensitive member or an intermediate transfer member. However, since a cleaning failure occurs due to various causes, countermeasures against the cleaning failure are taken.

  In Patent Document 1, it is proposed to provide two cleaning blades close to each other in order to perform good cleaning even when a small particle size toner is used.

  Patent Document 2 proposes that a metal scraper be provided downstream of the cleaning blade with respect to the moving direction of the image carrier to remove discharge products adhering to the surface of the image carrier.

Japanese Patent Laid-Open No. 2004-4224 JP 2007-34147 A

  With the advance of performance, image forming apparatuses that form high-quality images have come to use small particle size toners, particularly small particle size spherical toners. As described above, with the reduction in the particle size and the spherical shape of the toner, the cleaning defect is likely to occur due to the toner slipping through the cleaning device.

  Even if cleaning is performed with two cleaning blades as in Patent Document 1, it is difficult to sufficiently suppress toner slipping.

  If a metal scraper is used as in Patent Document 2, the toner is scraped and removed by the scraper, so that it is possible to prevent image defects caused by toner slipping in the cleaning device. In Patent Document 2, the discharge product adhering to the surface of the drum-shaped photoconductor is removed.

  However, when a metal scraper is used, if the surface of the image carrier has slight irregularities, the tip of the scraper is held by the moving image carrier or the surface of the image carrier is damaged. Occurred. That is, when the surface of the image carrier has irregularities, there are problems that the tip of the scraper is moved by the moving image carrier or that the image carrier is damaged by the scraper. Further, around the convex portion, a gap is formed between the image carrier and the scraper, and toner slips out.

  In the configuration in which the image carrier is in the form of a belt and is suspended on a belt support member such as a roller, when foreign matter adheres to the belt support member, the image carrier is supported by the belt support member. Then, the image carrier is pushed up by the foreign matter, and irregularities are generated on the surface of the image carrier. Further, on the belt support member, irregularities due to wrinkles and undulations are likely to occur on the image carrier. And the malfunction mentioned above generate | occur | produces with such an unevenness | corrugation.

  Such a problem is a problem peculiar to a belt-like image carrier and is not studied at all in Patent Document 2.

  In an image forming apparatus having a belt-like image carrier, the present invention prevents a cleaning failure by a scraper, and the tip of the scraper is carried by the image carrier or damages the image carrier. Another object of the present invention is to provide an image forming apparatus that prevents the toner from slipping out and maintains the cleaning performance of the cleaning apparatus well over a long period of time.

  The object is achieved by the following invention.

1. A belt-shaped image carrier, a tension roller that movably supports the image carrier, and adjusts the tension of the image carrier, and the tension roller are arranged at a distance from each other so that the image carrier can be moved. An image forming apparatus comprising: a belt support member supported on the image bearing member; a toner image forming unit that forms a toner image on the image carrier; and a cleaning device that cleans the image carrier.
A plate-shaped scraper for removing deposits on the image carrier;
An image forming apparatus, wherein the scraper is arranged so that a tip of the scraper is pressed against the image carrier between the tension roller and the belt support member.

  2. 2. The image forming apparatus according to 1 above, wherein the scraper is made of metal.

  3. 3. The image forming apparatus according to claim 1, wherein the scraper is rotatable about an axis, and has an urging unit that presses the scraper against the image carrier.

  4). The image forming apparatus according to any one of claims 1 to 3, wherein the scraper is displaced integrally with the tension roller.

  5). The image forming apparatus according to claim 1, wherein the cleaning device includes a cleaning blade.

  6). 6. The image forming apparatus according to 5, wherein the cleaning device has a toner storage member disposed upstream of the cleaning blade with respect to a moving direction of the image carrier.

  7). The image forming apparatus according to any one of claims 1 to 6, wherein the scraper is disposed downstream of the cleaning device with respect to a moving direction of the image carrier.

  8). The toner image forming unit includes: a photosensitive member; a latent image forming device that forms a latent image on the photosensitive member; a developing device that develops the latent image on the photosensitive member to form a toner image on the photosensitive member; 8. The image forming apparatus according to any one of 1 to 7, further comprising a transfer device that transfers a toner image on a photosensitive member to the image carrier.

  9. 9. The image forming apparatus according to 8, wherein the toner image forming unit includes a lubricant applying device that applies a lubricant onto the photoconductor.

  10. The image forming apparatus according to any one of 1 to 9, further comprising a lubricant application device that applies a lubricant to the image carrier.

  11. 11. The image forming apparatus according to any one of 1 to 10, wherein the toner constituting the toner image formed in the toner image forming unit contains a lubricant.

  12 The image forming apparatus according to any one of 1 to 11, wherein the toner constituting the toner image formed in the toner image forming unit contains a wax.

  In the present invention, a scraper that removes deposits on the image carrier is pressed against the image carrier between a plurality of support members.

  As a result, the scraper reliably removes the toner and foreign matter on the image carrier, and the tip of the scraper is taken away by the moving image carrier and the surface of the image carrier is prevented from being damaged. . Further, the toner is sufficiently prevented from slipping through the scraper.

1 is a diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a portion of an image forming apparatus in which a scraper 10 is disposed. It is a figure which shows the tension roller 6C. It is a figure which shows the scraper. It is a figure which shows the tension roller 6C displaced by a monochrome image formation mode and a color image formation mode. FIG. 5 is a diagram illustrating toner slipping.

  Hereinafter, the present invention will be described based on an embodiment of the present invention, but the present invention is not limited to the embodiment.

<Image forming apparatus>
FIG. 1 is a diagram showing an overall configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus shown in FIG. 1 is called a tandem color image forming apparatus, and includes four toner image forming units 20Y, 20M, 20C, and 20K, a transfer body unit 30, a secondary transfer apparatus 7A, A cleaning device 9, a scraper 10, and a fixing device 40 are provided.

  A toner image forming unit 20Y that forms a yellow toner image includes a latent image forming device including a photoreceptor 1Y, a charging device 2Y, and an exposure device 3Y, a developing device 4Y, a lubricant applying device 5Y, and a primary transfer device as a transfer device. 7Y and a cleaning device 8Y. A toner image forming unit 20M that forms a magenta toner image includes a latent image forming device including a photoreceptor 1M, a charging device 2M, and an exposure device 3M, a developing device 4M, a lubricant applying device 5M, and a primary transfer device as a transfer device. 7M and a cleaning device 8M. A toner image forming unit 20C that forms a cyan toner image is a latent image forming device including a photoreceptor 1C, a charging device 2C, and an exposure device 3C, a developing device 4C, a lubricant applying device 5C, and a primary transfer device as a transfer device. 7C and a cleaning device 8C. A toner image forming unit 20K that forms a black toner image includes a latent image forming device including a photoreceptor 1K, a charging device 2K, and an exposure device 3K, a developing device 4K, a lubricant applying device 5K, a primary transfer device 7K as a transfer device, and It has a cleaning device 8K.

  The lubricant application devices 5Y, 5M, 5C, and 5K apply lubricants such as zinc stearate to the surfaces of the photoreceptors 1Y, 1M, 1C, and 1K, respectively. Note that the lubricant may be contained in the toner as a component of the toner, and the lubricant application devices 5Y, 5M, 5C, and 5K may be omitted.

  The transfer body unit 30 includes an intermediate transfer body 6 as a belt-like image carrier and a plurality of rollers 6A to 6C as belt support members for supporting the belt-like image carrier. When the roller 6E that rotates by driving the motor that does not rotate is driven, it moves around as indicated by the arrow W2. The roller 6A is a backup roller facing the secondary transfer device 7A, and forms a transfer electric field with the secondary transfer device 7A to which a transfer voltage is applied. The roller 6C is a tension roller that corrects the offset of the intermediate transfer member 6 as will be described later.

  The primary transfer devices 7Y, 7M, 7C, and 7K are arranged to face the toner image forming portions 20Y, 20M, 20C, and 20K, respectively, and transfer rollers that press the intermediate transfer body 6 to the photoreceptors 1Y, 1M, 1C, and 1K, respectively. Have The transfer rollers of the primary transfer devices 7Y, 7M, 7C, and 7K each have a roller made of conductive rubber and a power source (not shown) that applies a transfer voltage to the transfer roller.

  The secondary transfer device 7A has a conductive rubber transfer roller and a power source (not shown) for applying a transfer voltage to the transfer roller.

  The cleaning device 9 is for cleaning the intermediate transfer body 6 after the secondary transfer, and the residual transfer toner, paper dust, lubricant on the intermediate transfer body 6 by a cleaning blade 9A as a cleaning means made of plate-like rubber. Scrape and remove.

In the toner image forming units 20Y, 20M, 20C, and 20K, the toner images formed on the photoreceptors 1Y, 1M, 1C, and 1K rotating as indicated by the arrow W1 are respectively transferred by the primary transfer devices 7Y, 7M, 7C, and 7K. Transferred to the intermediate transfer body 6. On the intermediate transfer member 6, the toner images formed in the toner image forming portions 20Y, 20M, 20C, and 20K are overlapped to form a color toner image. The color toner image on the intermediate transfer member 6 is transferred to the recording material P by the secondary transfer device 7A. The color toner image on the recording material P is fixed by the fixing device 40. The intermediate transfer body 6 after the transfer is cleaned by a cleaning device 9.
<Scraper>
2 is a view showing a portion of the image forming apparatus in which the scraper 10 is arranged, FIG. 3 is a view showing the tension roller 6C, and FIG. 4 is a view showing the scraper 10.

  The scraper 10 is disposed downstream of the cleaning device 9 and upstream of the primary transfer device 7Y, and the scraper 10 scrapes off toner, lubricant, wax, and the like adhering to the intermediate transfer member 6. For the scraper 10, for example, a plate-like member made of metal or resin such as a SUS plate having a thickness of 0.1 mm is used. Further, the scraper 10 contacts the intermediate transfer member 6 at a tip extending in a direction intersecting the intermediate transfer member 6 at an acute angle between the downstream side in the moving direction of the intermediate transfer member 6. That is, the scraper 10 contacts the intermediate transfer member 6 in a counter manner. The tension roller 6C and the scraper 10 are attached to the support member 11.

  Furthermore, the scraper 10 is installed between the roller 6B and the tension roller 6C so as to be in pressure contact with the intermediate transfer member 6. There is no member that supports the intermediate transfer member 6 between the belt support member and the belt support member, such as between the roller 6B and the tension roller 6C. Accordingly, when no force is applied to the intermediate transfer body 6 between the roller 6B and the tension roller 6C, the intermediate transfer body 6 forms a flat surface as indicated by a dotted line in this portion. When the tip of the scraper 10 is in pressure contact with the intermediate transfer member 6 that forms a flat surface, the intermediate transfer member 6 bends as shown by a solid line.

  The scraper 10 is rotatable about a base shaft 102 and is biased by a spring 103 as a biasing means so as to rotate in the direction of an arrow W3. In FIG. 4, the scraper 10 is fixed to a plate-like support member 101 at the base. The support member 101 is rotatable about a shaft 102 provided at both ends, and is biased by the springs 103 and 103 provided on the shafts 102 and 102 so that the support member 101 and the scraper 10 are rotated in the direction of the arrow W3. Is done.

  As shown in FIG. 3, the tension roller 6 </ b> C is urged upward by a spring 6 </ b> CA as indicated by an arrow W <b> 4 and applies a constant tension to the intermediate transfer body 6. Thus, the tension roller 6C adjusts the tension of the intermediate transfer member 6. When the tension of the intermediate transfer member 6 varies for some reason, the roller shaft 6CB moves up and down by the spring 6CA and is adjusted to a constant tension. The roller shaft 6CB is rotatably supported by the support member 11. As described above, since the scraper 10 is supported by the support member 11, the roller shaft 6CB and the scraper 10 are integrally displaced.

  In this way, the scraper 10 is pressed against the intermediate transfer body 6 stretched between the roller 6B and the tension roller 6C with a constant tension at a constant pressure, so that the contact angle of the scraper 10 with respect to the intermediate transfer body 6 is stabilized. Good scraping by 10 is performed. As a result, deposits such as toner, lubricant, and wax on the intermediate transfer member 6 are removed well.

  Since the tension roller 6C and the support member 11 are biased upward by the spring 6CA, they are displaced up and down as indicated by 6C1 and 6C2 in FIG. The tension roller 6C and the support member 11 move up and down by the tension adjusting action, but move up and down according to the image forming mode. FIG. 5 shows the tension roller 6C displaced in the monochrome image forming mode and the color image forming mode.

  In the color image forming mode, the intermediate transfer member 6 is set to the monochrome image forming mode in order to stably run the intermediate transfer member 6 at the transfer positions of the toner image forming units 20Y, 20M, 20C, and 20K (see FIG. 1). In comparison, a strong tension is applied. For this reason, the tension roller 6C moves downward to a position indicated by 6C2 to 6C1 in FIG.

  It is preferable that the scraper 10 is brought into pressure contact with the intermediate transfer member 6 with a constant load so that the contact pressure of the scraper 10 does not change even when the tension of the intermediate transfer member 6 changes. For this reason, it is preferable to use a biasing means that presses the scraper 10 against the intermediate transfer member 6 and has a characteristic of applying a constant load. From this point of view, a weight can be used instead of the spring 103 as the biasing means of the scraper 10.

  The scraper 10 is preferably disposed so as to be in close contact with the intermediate transfer member 6 forming a flat surface near the tension roller 6C. Specifically, the scraper 10 is in pressure contact with the intermediate transfer body 6 between the tension roller 6C and the other rollers, that is, the rollers 6B and 6D. As a result, it is possible to avoid the tip of the scraper 10 being dragged by the intermediate transfer member 6 or the intermediate transfer member 6 being damaged by the scraper 10. Further, toner can be prevented from slipping through. When the scraper 10 is pressed against the position of the roller 6B or 6D, that is, the intermediate transfer body 6 is in contact with and supported by the belt support member, the intermediate transfer is performed if foreign matter exists on the support member. The body 6 is lifted by the foreign matter, and a protrusion is formed on the surface of the intermediate transfer body 6. Alternatively, irregularities due to wrinkles and undulations are formed on the surface of the intermediate transfer member 6 supported by the support member. When the tip of the scraper 10 comes into contact with such unevenness, the tip is held by the unevenness, or the surface of the intermediate transfer member 6 is damaged. In addition, since a gap is formed between the intermediate transfer member 6 and the scraper 10 around the convex portion, toner passes through.

  By bringing the scraper 10 into pressure contact with the intermediate transfer member 6 between the roller 6B and the tension roller 6C or between the roller 6D and the tension roller 6C, the undesirable phenomenon is sufficiently suppressed.

  For example, in the example of FIG. 1, it is preferable that the tip of the scraper 10 is brought into contact with the intermediate transfer body 6 at the positions indicated by P1 and P5.

  Toner, lubricant, wax, and the like adhere to the surface of the intermediate transfer member 6 that has passed through the cleaning device 9.

  The lubricant is applied to the photoreceptors 1Y, 1M, 1C, and 1K by the lubricant application devices 5Y, 5M, 5C, and 5K, and moved to the intermediate transfer member 6 in the primary transfer. Further, the wax contained in the toner is separated from the toner and adhered to the intermediate transfer member 6. The lubricant may be contained in the toner. In the toner containing the lubricant, the lubricant is separated from the toner and adheres to the intermediate transfer member 6. A lubricant application device that applies a lubricant to the intermediate transfer member 6 may be provided.

  The amount of lubricant and wax that moves from the toner image forming portions 20Y, 20M, 20C, and 20K and adheres to the intermediate transfer member 6 differs between the image portion and the non-image portion, and also varies depending on the density of the image. On the intermediate transfer member 6, lubricant and wax are deposited in a non-uniform distribution.

  As described above, in the case where deposits are present in a non-uniform distribution on the intermediate transfer member 6, a cleaning failure occurs in the cleaning device 9.

  Such a cleaning failure occurs when the cleaning means is a cleaning blade or a cleaning brush. The cleaning failure when the cleaning means is a cleaning blade is considered to be due to the phenomenon described below.

  When a non-uniform layer of lubricant or wax is formed on the surface of the intermediate transfer member 6, slight cleaning occurs on the cleaning edge 9AE of the cleaning blade 9A as shown in FIG. As a result, the toner slips through the cleaning blade 9A due to the curling, resulting in poor cleaning.

  The scraper 10 described above removes such foreign matter together with the toner that has passed through the cleaning blade 9A. As a result, the surface of the intermediate transfer member 6 is cleaned and defective cleaning in the cleaning device 9 is prevented, and a high-quality image can be formed over a long period of time.

  In the cleaning device 9, it is preferable to provide a toner storage member upstream of the cleaning blade 9A. A brush or the like is used as the toner storage member.

  As described above, the deposit on the intermediate transfer body 6 is removed by the scraper 10, but the toner image is formed on the intermediate transfer body 6 from which the deposit has been removed, that is, it passes through the scraper 10. The toner image is transferred from the toner image forming portions 20Y, 20M, 20C, and 20K onto the intermediate transfer member 6 and the color toner image is transferred to the recording material by the secondary transfer device 7A. In the image forming process for cleaning with the cleaning device 9, it is desirable that toner as a lubricant is present on the surface of the intermediate transfer body 6 with respect to the cleaning blade 9 </ b> A. The toner storage member collects and stores toner from the intermediate transfer member 6 and applies appropriate toner to the intermediate transfer member 6.

Image formation was performed under the following conditions.
・ Scraper Material: SUS, Etching treatment Thickness: 1mm
Free length: 10mm
Scraper contact load: 17 N / m
Contact angle: 7 °
・ Cleaning blade Material: Urethane rubber Thickness: 2mm
Free length: 9mm
Contact load: 24N
Contact angle: 17 °
Black and white image formation and color image formation were performed. In 300 kp image formation, there was no slipping of toner in the cleaning device, and good cleaning was performed.

  Table 1 shows the tension of the intermediate transfer member in the full-color image forming mode, and Table 2 shows the tension of the intermediate transfer member in the monochrome image forming mode.

  The tension is a load applied to the roller when the roller is pressed against the intermediate transfer member and the intermediate transfer member forming a flat surface starts to bend. The tension was measured three times in each of the full-color image formation mode and the monochrome image formation mode.

  In Table 1, P1 to P5 are tensions of the intermediate transfer member at the positions indicated by P1 to P5 in FIG.

  As shown in Tables 1 and 2, the difference between the measured values obtained by performing the test three times was small at the positions P1 and P5, and there was little fluctuation in the tension. That is, the tension of the intermediate transfer member is stable in the vicinity of the tension roller. Therefore, it is preferable to provide a scraper at the positions P1 and P5.

1Y, 1M, 1C, 1K photoconductor 2Y, 2M, 2C, 2K charging device 3Y, 3M, 3C, 3K exposure device 4Y, 4M, 4C, 4K developing device 5Y, 5M, 5C, 5K lubricant coating device 6 Intermediate transfer member 6C Tension roller 7Y, 7M, 7C, 7K Primary transfer device 7A Secondary transfer device 10 Scraper 20Y, 20M, 20C, 20K Toner image forming unit 103 Spring

Claims (12)

A belt-shaped image carrier, a tension roller that movably supports the image carrier, and adjusts the tension of the image carrier, and the tension roller are arranged at a distance from each other so that the image carrier can be moved. An image forming apparatus comprising: a belt support member supported on the image bearing member; a toner image forming unit that forms a toner image on the image carrier; and a cleaning device that cleans the image carrier.
A plate-shaped scraper for removing deposits on the image carrier;
An image forming apparatus, wherein the scraper is arranged so that a tip of the scraper is pressed against the image carrier between the tension roller and the belt support member.   The image forming apparatus according to claim 1, wherein the scraper is made of metal.   3. The image forming apparatus according to claim 1, wherein the scraper is rotatable about an axis, and has an urging unit that presses the scraper against the image carrier. 4.   The image forming apparatus according to claim 1, wherein the scraper is integrally displaced with the tension roller.   The image forming apparatus according to claim 1, wherein the cleaning device includes a cleaning blade.   The image forming apparatus according to claim 5, wherein the cleaning device includes a toner storage member disposed upstream of the cleaning blade with respect to a moving direction of the image carrier.   The image forming apparatus according to claim 1, wherein the scraper is disposed downstream of the cleaning device with respect to a moving direction of the image carrier.   The toner image forming unit includes: a photosensitive member; a latent image forming device that forms a latent image on the photosensitive member; a developing device that develops the latent image on the photosensitive member to form a toner image on the photosensitive member; The image forming apparatus according to claim 1, further comprising a transfer device that transfers a toner image on a photosensitive member to the image carrier.   The image forming apparatus according to claim 8, wherein the toner image forming unit includes a lubricant applying device that applies a lubricant to the photosensitive member.   The image forming apparatus according to claim 1, further comprising a lubricant application device that applies a lubricant to the image carrier.   The image forming apparatus according to claim 1, wherein the toner constituting the toner image formed in the toner image forming unit contains a lubricant.   The image forming apparatus according to claim 1, wherein the toner constituting the toner image formed in the toner image forming unit contains wax.

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