JP2005227653A - Cleaning apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning apparatus obtaining a good image without any white stripes over a long period of time by preventing curling up of a cleaning blade or damage to an edge even when continuous copying is carried out using an original of low printed ratio or narrow size paper and furthermore preventing occurrence of slipping or filming. <P>SOLUTION: A cleaning blade eliminating transfer residual toner from an intermediate transfer body after secondary transferring is carried out of a toner image formed on the intermediate transfer body to recording material and a toner application means installed on a upstream side in the rotating direction of the intermediate transfer body and applying the eliminated toner by the cleaning blade to the intermediate transfer body are provided. The quantity of the toner applied to the intermediate transfer body by the toner application means is ≥0.2 mg/cm<SP>2</SP>and ≤0.6 mg/cm<SP>2</SP>. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus for primary transfer of a toner image formed on an image carrier to an intermediate transfer member, and secondary transfer of the toner image transferred to the intermediate transfer member to a recording material to form an image. The present invention relates to a cleaning device for removing toner remaining on a body.

  Technology that primarily transfers the toner image formed on the image bearing member to the intermediate transfer member, secondarily transfers the toner image transferred to the intermediate transfer member to the recording material, and removes transfer residual toner on the intermediate transfer member with a cleaning blade. Is conventionally known.

  The toner is composed of a mixture of a base material and an external additive. The base material is made of a pigment, wax, resin, or the like, and the external additive is made of abrasive particles or a lubricant for imparting electrification such as silica or titania.

  When the transfer residual toner on the intermediate transfer member is removed by the cleaning blade, the transfer residual toner is scraped off at the edge of the cleaning blade, but a part of the toner is attached to the edge. Abrasive particles contained in the toner also serve as a lubricant, and a small amount enters the gap between the edge and the intermediate transfer member to lower the coefficient of friction between the cleaning blade and the intermediate transfer member. It is possible to continue removing the transfer residual toner without causing the toner.

  However, in reality, the wax or the lubricant contained in the toner partially adheres to the intermediate transfer member and is stretched without being sufficiently polished and removed by the cleaning blade to form a thin film. Ming phenomenon occurs.

  Further, it is necessary that the toner always stays at the edge. However, when the printing rate at which copying is performed only on a part of the sheet is low, the toner becomes deficient if many such copies are made. If the toner is deficient, the coefficient of friction between the cleaning blade and the intermediate transfer member increases, so that the edge of the cleaning blade at the deficient portion is damaged, and the wax or the sliding material slips through the portion to cause filming.

  When filming occurs in the intermediate transfer member, the electrical resistance of the portion increases, and as a result, the charge preferentially flows in the primary transfer and secondary transfer where no filming occurs. Transferability deteriorates and white streaks occur on the recording material.

  The following patent documents are disclosed with respect to such a problem.

  For one, image formation having a cleaning member that uses a function of cleaning a transfer residual toner on an intermediate transfer body by being indirectly biased by a cleaning bias applying member and a function of applying a lubricant to the intermediate transfer body. An apparatus is disclosed (Patent Document 1).

In addition, even when only primary transfer is performed without using an intermediate transfer member, the surface of the image carrier is mirror-finished with use, the frictional resistance between the image carrier and the cleaning blade is increased, the blade is turned up, Damage and wear occur. For this reason, the specularity of the surface of the image carrier is detected by a reflection type optical sensor, and when the surface of the image carrier is in a mirror state, more toner acts as a lubricant on the non-image portion of the image carrier. A cleaning device is disclosed (see Patent Document 2).
JP 2002-268400 A JP-A-6-318019

  The present invention solves the above-mentioned problem from a viewpoint different from that of the above-mentioned patent document. By feeding an appropriate amount of toner into the gap between the edge of the cleaning blade and the intermediate transfer member, an original with a low printing rate can be used or a small width can be obtained. Even when paper of a size is transported and continuous copying is performed, the cleaning blade is prevented from turning over and the edges are damaged. It is an object of the present invention to provide a cleaning device and an image forming apparatus obtained over the above.

The above object can be achieved by any of the following means.
(1) A cleaning blade that removes transfer residual toner after the toner image formed on the intermediate transfer member is secondarily transferred to the recording material from the intermediate transfer member, and an upstream side in the rotation direction of the intermediate transfer member. And a toner applying unit that applies the toner removed by the cleaning blade to the intermediate transfer member, and the amount of toner applied to the intermediate transfer member by the toner applying unit is 0.2 mg / cm ² or more, 0 . Cleaning device characterized by being 6 mg / cm ² or less.
(2) In an image forming apparatus in which a toner image formed on an image carrier is primarily transferred to an intermediate transfer member, and the toner image transferred to the intermediate transfer member is secondarily transferred to a recording material to form an image. A cleaning blade that removes transfer residual toner after the next transfer from the intermediate transfer body, and a toner that is positioned upstream in the rotation direction of the intermediate transfer body and removed by the cleaning blade is applied to the intermediate transfer body. A toner application unit; and a storage unit that stores a belt image, and the belt image stored in the storage unit is formed on the intermediate transfer member as a toner image for each predetermined movement distance of the intermediate transfer member. An image forming apparatus.
(3) In an image forming apparatus in which a toner image formed on an image carrier is primarily transferred to an intermediate transfer member, and the toner image transferred to the intermediate transfer member is secondarily transferred to a recording material to form an image. A cleaning blade that removes transfer residual toner after the next transfer from the intermediate transfer body, and a toner that is positioned upstream in the rotation direction of the intermediate transfer body and removed by the cleaning blade is applied to the intermediate transfer body. A toner applying unit; a detecting unit that detects the amount of the toner remaining after transfer; and a storage unit that stores a band image. The detecting unit detects that the toner amount is 0.2 mg / cm ² or less. In this case, the image forming apparatus is characterized in that the band image stored in the storage unit is formed on the intermediate transfer member as a toner image.

  According to the cleaning device and the image forming apparatus of the present invention, an appropriate amount of toner is fed into the gap between the edge of the cleaning blade and the intermediate transfer member, thereby using a document with a low printing rate or conveying a small width sheet. Even when continuous copying is performed, the cleaning blade is prevented from being turned over and the edges are damaged, and further, the occurrence of slip-out and filming is prevented, and a good image free of white stripes can be obtained over a long period of time.

  First, FIG. 1 shows an example of a color image forming apparatus that primarily transfers a toner image formed on an image carrier to an intermediate transfer member, and secondary transfers the toner image transferred to the intermediate transfer member to a recording material to form an image. The description will be given with reference. FIG. 1 is a configuration diagram of a color image forming apparatus.

  The color image forming apparatus shown in FIG. 1 includes an image forming apparatus 100 and an image reading apparatus 200.

  The image forming apparatus 100 is called a tandem color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, a belt-like intermediate transfer member 6, a sheet feeding and conveying unit 20, and details later. And a belt fixing device 30 described below.

  An image reading device 200 including an automatic document feeder 201 and a document image scanning exposure device 202 is installed on the image forming apparatus 100.

  The document d placed on the document table of the automatic document feeder 201 is transported by a transport unit, and an image on one or both sides of the document is scanned and exposed by the optical system of the document image scanning exposure device 202, and the line image sensor CCD is scanned. Is read.

  The analog signal photoelectrically converted by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing and the like in the image processing unit 101, and then input to the exposure means 3Y, 3M, 3C, 3K. Is done.

  The image forming unit 10Y that forms a yellow (Y) image includes a charging unit 2Y, an exposure unit 3Y, a developing device 4Y, and a cleaning unit 5Y disposed around a photosensitive drum 1Y as an image carrier. The image forming unit 10M that forms a magenta (M) color image includes a photosensitive drum 1M as an image carrier, a charging unit 2M, an exposure unit 3M, a developing device 4M, and a cleaning unit 5M. An image forming unit 10C for forming a cyan (C) color image includes a photosensitive drum 1C as an image carrier, a charging unit 2C, an exposure unit 3C, a developing device 4C, and a cleaning unit 5C. The image forming unit 10K that forms a black (K) image includes a photosensitive drum 1K as an image carrier, a charging unit 2K, an exposure unit 3K, a developing device 4K, and a cleaning unit 5K. The charging unit 2Y and the exposure unit 3Y, the charging unit 2M and the exposure unit 3M, the charging unit 2C and the exposure device 3C, and the charging unit 2K and the exposure device 3K constitute a latent image forming unit.

  The developing devices 4Y, 4M, 4C, and 4K include a two-component developer including yellow (Y), magenta (M), cyan (C), and black (K) small particle size toners and a carrier.

  The intermediate transfer member 6 is wound around a plurality of rollers and is rotatably supported.

  The images of the respective colors formed by the image forming units 10Y, 10M, 10C, and 10K are sequentially transferred (primary transfer) and synthesized by the primary transfer units 7Y, 7M, 7C, and 7K on the rotating intermediate transfer body 6. A color image is formed.

  The recording material P accommodated in the paper feeding cassette 21 of the paper feeding / conveying means 20 is fed by the paper feeding means 22, passes through the paper feeding rollers 23, 24, 25, 26, the registration rollers 27, etc., and then the transfer roller 9. The color image on the intermediate transfer body 6 is transferred onto the recording material P (secondary transfer).

  The recording material P onto which the color image has been transferred is sandwiched by the belt fixing device 30, and heat and pressure are applied to fix the toner image on the recording material P, and the toner image is fixed on the recording material P. It is sandwiched between rollers 28. Thereafter, the sheet is placed on a discharge tray 29 outside the apparatus.

  On the other hand, after the color image is transferred to the recording material P by the transfer roller 9, the residual transfer toner is removed by the cleaning unit 8 from the intermediate transfer body 6 from which the recording material P is separated by curvature.

  When the recording material P that has been subjected to the fixing process is reversed and discharged, the recording material P passes through the conveyance path on the right side of the branch plate 28A disposed between the belt fixing device 30 and the discharge roller 28, and the lower side. After being transported to the first transport path <1>, it is transported in reverse, passes through the second transport path <2> on the left side of the branch plate 28A, and is discharged out of the apparatus by the paper discharge roller 28.

  When copying on both surfaces of the recording material P, after fixing the image formed on the first surface of the recording material P, the recording material P is moved to the first conveyance path <1>, and further to the fourth below the branch plate 28B. After being introduced into the transport path <4>, it is transported in the reverse direction, passed through the transport path on the right side of the branch plate 28B, transported to the third transport path <3>, and then detoured upward and transported by the paper feed roller 26. . The recording material P is formed with images of the respective colors on the second surface by the image forming means 10Y, 10M, 10C, and 10K, heated and fixed by the belt fixing device 30, and discharged to the outside by the paper discharge roller 28.

  Although the above image forming apparatus has been described as a color image forming apparatus, a monochrome image forming apparatus may be used if an intermediate transfer member is used.

  Next, the cleaning means 8 according to the present invention will be described in detail.

  FIG. 2 is an enlarged view of the cleaning means 8. Reference numeral 6 denotes the above-described intermediate transfer member, which is wound around the backup roller 61 and rotates in the direction of the arrow.

  Reference numeral 81 denotes a cleaning blade made of urethane rubber or the like, and is in sliding contact with the peripheral surface of the intermediate transfer body 6 diagonally from the counter type. Then, the transfer residual toner adhering to the intermediate transfer body 6 after the secondary transfer to the recording material P is scraped off by the edge which is the tip of the cleaning blade 81. A brush roller 82 is formed of conductive acrylic fiber or the like, and is rotated counterclockwise by a driving source (not shown). Then, the brush roller 82 drops the transfer residual toner scraped off by the cleaning blade 81 to the left. The dropped transfer residual toner is transported by the transport screw 83 and collected in a predetermined container.

  Here, a toner storage member 84 is fixed below the brush roller 82, and a part of the transfer residual toner scraped off by the cleaning blade 81 is stored in the gap between the brush roller 82 and the toner storage member 84. A toner storage portion 85 is formed. A urethane sheet 86 is in sliding contact with the intermediate transfer member 6 so that the transfer residual toner does not fall from the right side.

  In this way, a part of the transfer residual toner scraped off from the intermediate transfer body 6 by the cleaning blade 81 is stored in the toner storage section 85, and is attached to the intermediate transfer body 6 by the rotation of the brush roller 82 and supplied upward. Then, it is scraped off again at the edge of the cleaning blade 81, but a small amount of untransferred toner remains attached to the edge of the cleaning blade 81. Therefore, the friction coefficient between the cleaning blade 81 and the intermediate transfer member 6 is kept low, and even when copying with a low printing rate is performed for a long time, the blade is not turned over, the edge is not damaged, etc. Does not occur.

Next, an experiment was conducted on the relationship between the supply amount of the transfer residual toner that adheres to the intermediate transfer member 6 by the rotation of the brush roller 82 and is supplied upward, and the amount of white streaks generated.
[Experiment 1]
(1) Experimental conditions Experimental machine: tandem full-color copier Photosensitive drum: outer diameter 60 mm, coated with a phthalocyanine pigment dispersed in polycarbonate as an organic semiconductor layer, film thickness of photosensitive layer including charge transport layer 25 μm
Photoreceptor non-image part potential: Detected by potential sensor and feedback controlled, controllable range is -500V to -900V
Total exposure potential: -50V to 0V
Exposure: Laser scanning system, semiconductor laser power is 300μW
Development: Two-component development system Intermediate transfer member: Seamless semiconductive resin belt, rotational speed 220 mm / s, surface resistivity 1 × 10 ¹¹ Ω / □, volume resistivity 1 × 10 ⁸ Ω · cm, tension 50 N
Primary transfer means: A primary transfer roller (outer diameter 20 mm, resistance value 1 × 10 ⁶ Ω, roller pressure 5 N) is installed on the back surface of the intermediate transfer member, and a predetermined current is set in a current value table in which a matrix is formed by temperature and humidity and a counter. Secondary transfer means: The intermediate transfer member is sandwiched between the backup roller and the secondary transfer roller, the resistance value is 1 × 10 ⁷ , and the current value table in which the matrix is formed by the temperature and humidity and the counter Select and apply current value Cleaning blade for intermediate transfer member: urethane rubber, free length 9 mm, thickness 2 mm, contact angle 17 degrees Toner storage member: arranged upstream of cleaning blade Brush roller: made of conductive acrylic fiber, 6.25 denier 100,000 / 2.54cm ²
Under the above conditions, the height h of the toner storage member 84 is changed to change the volume of the toner storage portion 85, and the rotation speed of the brush roller 82 is changed to change the toner supply amount by the brush roller 82 from 0.05 to 0.05. It was changed to 0.6 mg / cm ² . Then, for each toner supply amount, 5 sheets of A4 size paper were intermittently fed laterally to make color copies, and a total of 100,000 copies were made. The paper document used a character chart of 5% printing for each color.
(2) Experimental results Table 1 shows.

  Every 10,000 copies, a full-size halftone original in A3 size was copied, and the occurrence of white streaks due to filming was evaluated by ○, Δ, and ×. The white streaks were visually observed and evaluated under the following conditions.

○: No white streaks appear on the image Δ: Five or less white streaks appear on the image ×: Six or more white streaks appear on the image Note that the height h of the toner storage member 84 is changed. Even when the volume of the toner reservoir 85 was changed and the rotation speed of the brush roller 82 was changed, the toner supply amount did not exceed 0.6 mg / cm ² .
[Experiment 2]
(1) Experimental conditions Under the conditions of Experiment 1, toner was stored in advance in the toner storage unit 85 before the experiment, and copying was performed using a document with a printing rate of 0% for each color.
(2) Experimental results As a result, as the number of copies increased, the toner supply amount gradually decreased, and the occurrence of white streaks due to filming became “x” at 20,000 copies.

  Therefore, the band image is stored in the memory 102 (storage means), and the band image is formed on the intermediate transfer body 6 as a toner image for each moving distance of the intermediate transfer body 6 under the following conditions, and the secondary transfer is not performed. The band image was formed in a size of 320 mm in the main scanning direction (larger than the long side of A4 size and the maximum printing width) and 10 mm in the sub-scanning direction. In addition, the band images were formed in four colors Y, M, C, and K, and each color was formed with a length of 2.5 mm in the sub-scan direction.

Experiment a
A belt image was formed every time the moving distance of the intermediate transfer body 6 reached 5 m using a B5 paper with a length (257 mm) and a document having a printing rate of 10% for each color.

  As a result, no white streak occurred even with 100,000 copies. That is, in a narrow paper having a width of about 260 mm or less, there is a portion where toner from the paper does not adhere to both ends of the edge of the cleaning blade, but a band image having a width wider than the paper width (maximum print width) is intermittently formed. As a result, toner adheres to both ends of the edge of the cleaning blade, so that the friction coefficient between the cleaning blade and the intermediate transfer member does not increase.

Experiment b
A4 paper is placed vertically (297 mm), and a belt image is formed every time the moving distance of the intermediate transfer body 6 reaches 20 m for a document with a printing rate of 0% for each color and a document with a printing rate of 5% for each color. did.

As a result, no white streak occurred even with 100,000 copies. That is, when a document with a wide width exceeding 260 mm and a printing rate of 5% or less is copied, the toner adhering to the edge of the cleaning blade gradually decreases, and the friction coefficient between the cleaning blade and the intermediate transfer member increases. However, an increase in the coefficient of friction could be prevented by intermittently forming a band image having the maximum print width.
[Experiment 3]
(1) Experimental Conditions Under the conditions of Experiment 1, as shown in FIG. 3, three diffuse reflection type optical sensors 91 (detecting means) are arranged between the cleaning blade 81 and the brush roller 82 in the paper width direction (center portion). The surface reflectance of the intermediate transfer body 6 to which the toner adhered was detected. As a result, as the amount of toner decreased, the surface reflectance increased and the amount of light received by the optical sensor 91 increased. When the toner amount was 0.2 mg / cm ² or less, the output value from the optical sensor 91 exceeded 2V. Therefore, when the output value from any of the optical sensors 91 exceeds 2V, the toner band as described above is formed.

In addition, color copies were made by intermittently feeding 5 sheets of A4 size paper at a time, and a total of 100,000 copies were made. Further, a character chart of 5% printing for each color was used for the paper document.
(2) Experimental results A full-size halftone original was copied in A3 size every 10,000 copies, and the occurrence of white streaks due to filming was evaluated. As a result, no white streaks were found.

1 is a configuration diagram of a color image forming apparatus. It is an enlarged view of a cleaning means. It is an enlarged view of the cleaning means provided with the optical sensor.

Explanation of symbols

P Recording material 1Y, 1M, 1C, 1K Photosensitive drum 6 Intermediate transfer member 81 Cleaning blade 82 Brush roller 84 Toner storage member 85 Toner storage portion 91 Optical sensor 102 Memory

Claims (9)

A cleaning blade for removing residual transfer toner after the toner image formed on the intermediate transfer body is secondarily transferred to the recording material from the intermediate transfer body;
A toner applying unit that is positioned upstream in the rotation direction of the intermediate transfer member and applies the toner removed by the cleaning blade to the intermediate transfer member;
A cleaning device, wherein an amount of toner applied to the intermediate transfer member by the toner applying unit is 0.2 mg / cm ² or more and 0.6 mg / cm ² or less. The toner application unit includes a toner storage member that stores toner removed by the cleaning blade, and a brush roller that contacts the intermediate transfer member and applies toner stored in the toner storage member to the intermediate transfer member. The cleaning apparatus according to claim 1. An image forming apparatus comprising the cleaning device according to claim 1. In an image forming apparatus that primarily transfers a toner image formed on an image carrier to an intermediate transfer member, and secondarily transfers the toner image transferred to the intermediate transfer member to a recording material to form an image.
A cleaning blade that removes transfer residual toner after secondary transfer to the recording material from the intermediate transfer member;
A toner applying unit that is positioned upstream in the rotation direction of the intermediate transfer member and applies the toner removed by the cleaning blade to the intermediate transfer member;
Storage means for storing the belt image,
An image forming apparatus, wherein a belt image stored in the storage unit is formed on the intermediate transfer member as a toner image at every predetermined moving distance of the intermediate transfer member. When the width of the recording material is 260 mm or less, a band image having a maximum printing width in the main scanning direction and a length of at least 10 mm in the sub-scanning direction every time the moving distance of the intermediate transfer member is at least 5 m. The image forming apparatus according to claim 4, wherein the image forming apparatus is formed on the intermediate transfer member. When the width of the recording material exceeds 260 mm and the printing rate is 5% or less, every time the moving distance of the intermediate transfer member is at least 20 m, the maximum printing width in the main scanning direction and the sub scanning direction. The image forming apparatus according to claim 4, wherein a belt image having a length of at least 10 mm is formed on the intermediate transfer member. In an image forming apparatus that primarily transfers a toner image formed on an image carrier to an intermediate transfer member, and secondarily transfers the toner image transferred to the intermediate transfer member to a recording material to form an image.
A cleaning blade that removes transfer residual toner after secondary transfer to the recording material from the intermediate transfer member;
A toner applying unit that is positioned upstream in the rotation direction of the intermediate transfer member and applies the toner removed by the cleaning blade to the intermediate transfer member;
Detecting means for detecting the amount of the transfer residual toner;
Storage means for storing the belt image,
When the detection unit detects that the toner amount is 0.2 mg / cm ² or less, the band image stored in the storage unit is formed on the intermediate transfer member as a toner image. apparatus. 8. The image forming apparatus according to claim 7, wherein the band image has a maximum printing width in the main scanning direction and a length of at least 10 mm in the sub scanning direction. The image forming apparatus according to claim 7, wherein the detection unit is an optical sensor.

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