JP2001042736A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hardly turn up a cleaning blade even in the case of increasing the contact pressure and/or contact angle of the cleaning blade by always heaping the toner scraped by the cleaning blade at the contact part of the cleaning blade with an image carrier and a part just below the contact part. SOLUTION: The toner T remaining on the image carrier after the toner image on the image carrier is transferred is scraped and removed by the cleaning blade 21 in contact with the surface of the image carrier 10. Then, the toner T scraped by the blade 21 is always heaped at the contact part C of the blade 21 with the image carrier 10 and the part U just below the contact part C. Therefore, the toner T is always supplied to the contact part of the blade 21 with the rotating image carrier 10 without being affected by an image pattern. Since the toner T has a function as lubricant, frictional force between the blade 21 and the surface of the photoreceptor gets low and the blade 21 is hardly turned up.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, a facsimile, a copying machine, etc., for forming an image by using an electrophotographic technique. In particular, the present invention relates to a cleaning device using a cleaning blade (hereinafter, simply referred to as a blade) for removing residual toner on an image carrier that carries the toner image.

[0002]

2. Description of the Related Art Generally, an image forming apparatus using an electrophotographic technique has a photosensitive member (an example of an image carrier) having a photosensitive layer on an outer peripheral surface, and a charging means for uniformly charging the outer peripheral surface of the photosensitive member. Exposure means for selectively exposing the outer peripheral surface uniformly charged by the charging means to form an electrostatic latent image; and toner as a developer on the electrostatic latent image formed by the exposure means Developing means for giving a visible image (toner image) by applying
Transfer means for transferring the toner image developed by the developing means onto a transfer medium such as paper; and contacting the surface of the photoreceptor to scrape off toner (residual toner) remaining on the outer peripheral surface of the photoreceptor after transfer. A cleaning device using a cleaning blade for removing and removing the cleaning blade.

Further, as a transfer means, in order to transfer the toner image on the photoconductor to a recording medium such as paper, the toner image formed on the photoconductor is transferred (primary transfer) and carried thereon. There is known an image forming apparatus provided with an intermediate transfer member (an example of an image carrier) that further transfers (secondarily transfers) the toner image to a recording medium. This intermediate transfer member is also provided with a cleaning blade for scraping off and removing toner (residual toner) remaining on the surface after the transfer of the toner image.

[0004]

In recent years, in an image forming apparatus using an electrophotographic technique, high image quality (small particle size of toner), high speed, and long life have been desired. In order to meet this demand, in particular, the demand for higher image quality (smaller particle size of toner), it is necessary to improve the cleaning property in order to satisfactorily remove the toner remaining on the image carrier after transferring the toner image. As one measure for this, it is conceivable to increase the contact pressure and / or contact angle of the cleaning blade with respect to the surface of the image carrier.

However, when the contact pressure of the cleaning blade against the surface of the image carrier is increased, the frictional force between the blade and the surface of the image carrier increases, and especially when the contact angle is increased, the blade is turned up. The problem that it becomes easy occurs. This turning of the blade is particularly likely to occur when an image pattern with a small amount of residual toner on the surface of the image carrier is formed, or in a high-temperature, high-humidity environment.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide an image forming apparatus in which even when the contact pressure and / or contact angle of the cleaning blade is increased, the blade is unlikely to be turned.

[0007]

According to a first aspect of the present invention, there is provided an image forming apparatus, comprising: an image carrier which is a rotating body for carrying a toner image; A cleaning blade for scraping toner remaining on the image carrier after the toner image on the image carrier is transferred, wherein a contact portion between the image carrier and the cleaning blade is provided. The toner scraped off by the cleaning blade is always deposited immediately below the cleaning blade. The image forming apparatus according to claim 2, wherein the angle of repose of the toner is α, and the rotation of the image carrier is based on a perpendicular passing through the center of rotation of the image carrier at the contact portion. When the angle from the perpendicular to the contact portion is β, the direction opposite to the direction is the forward direction, β is equal to or less than α.

[0008]

According to the image forming apparatus of the first aspect, the toner remaining on the image carrier after the transfer of the toner image on the image carrier, which is a rotating body for carrying the toner image, is performed by the image forming apparatus. It is scraped off and removed by a cleaning blade that contacts the surface of the carrier. According to the image forming apparatus of the present invention, the toner scraped off by the blade is constantly deposited on the contact portion between the image carrier and the cleaning blade and directly below the contact portion. The action as a lubricant makes it difficult for the blade to be turned up as described below. That is, since the toner scraped off by the blade is constantly deposited on the contact portion between the image carrier and the cleaning blade and directly below the same, the image pattern is formed on the contact portion between the rotating image carrier and the cleaning blade. The toner is always supplied without being affected by the toner. Since the toner acts as a lubricant, the presence of the toner reduces the frictional force between the blade and the surface of the image carrier, and as a result, increases the contact pressure and / or contact angle of the blade. However, the blade is hardly turned up. Also for the same reason,
Even under a high-temperature and high-humidity environment, the blade is hardly turned. As described above, according to the image forming apparatus of the first aspect, even when the contact pressure and / or contact angle of the cleaning blade is increased, the blade is less likely to be turned. Moreover, the cleaning blade removes the toner by a so-called stick-slip behavior. However, according to the image forming apparatus of the first aspect, the frictional force between the blade and the surface of the image carrier is reduced. The above behavior is stabilized, and as a result, the cleaning performance is further improved.

As a conventional cleaning device, as shown in FIG. 7A or 7B, a contact portion below the contact portion C between the image carrier 1 and the cleaning blade 3 rotating in the direction of arrow A. Space S provided at an interval from C
It is known that toner is deposited on the paper and various foreign substances deposited on the paper are removed by the deposited toner (Japanese Patent Laid-Open No. 1-161288). The toner is deposited in a space S provided below the contact portion C of the cleaning blade 3 with the contact portion C at a distance from the contact portion C, and the contact between the image carrier and the cleaning blade is made as in the above-mentioned invention. Since the toner is not deposited on the portion and immediately below the portion, the above-described operation and effect according to the first aspect cannot be obtained.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the angle of repose of the toner is α, and a vertical line passing through the center of rotation of the image carrier at the contact portion is used as a reference. When the angle from the perpendicular to the contact portion is β when β is the direction opposite to the rotation direction of the image carrier and β is less than α, there is no need to provide a special toner accumulation member. Depending on the surface of the image carrier,
The toner can be deposited on the contact portion between the image carrier and the cleaning blade and directly below the contact portion.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 is a schematic front sectional view showing a first embodiment of an image forming apparatus according to the present invention, and FIG. 2 is an enlarged view of a main part thereof.

This image forming apparatus is an apparatus capable of forming a full-color image using a developing device using four color toners of yellow (Y), cyan (C), magenta (M), and black (K). .

In FIG. 1, reference numeral 10 denotes a photoreceptor as an image carrier, which is rotationally driven by an appropriate driving means (not shown) in a direction indicated by an arrow. Around the photoreceptor 10, along a rotation direction thereof, a charging roller 12 as a charging unit,
Developing roller 13 (Y, C, M, K) as developing means,
An intermediate transfer device 30 and a cleaning device 20 are provided.

The charging roller 12 contacts the outer peripheral surface of the photoconductor 10 to uniformly charge the outer peripheral surface. An outer peripheral surface of the uniformly charged photoconductor 10 is subjected to selective exposure L according to desired image information by an exposure unit (not shown), and an electrostatic latent image is formed on the photoconductor 10 by the exposure L. You. This electrostatic latent image is developed with toner applied by a developing roller 13. In this embodiment, a developing roller 13Y for yellow, a developing roller 13C for cyan, a developing roller 13M for magenta, and a developing roller 13K for black are provided as developing rollers. These developing rollers 13Y, 13C, 13M, and 13K can selectively contact the photoconductor 10, and when they come into contact with each other, apply any one of yellow, cyan, magenta, and black toner to the photoconductor 10. The electrostatic latent image on the photoconductor 10 is developed by being applied to the surface of the photoconductor 10. The developed toner image is
The image is transferred onto an intermediate transfer belt 36 as an intermediate transfer body described later (see the primary transfer unit Tr1).

After the transfer, the cleaning device 20
A photosensitive member blade (cleaning blade) 21 for scraping off the toner (residual toner) T remaining on and adhering to the outer peripheral surface of the photoreceptor 10, and a scooping sheet 22 for scraping the toner that is scraped off by the blade 21 and falls Stacking section 23 for stacking the falling toner, and the stacking section 23
A receiving portion 24 for receiving the toner overflowing from the container, a screw 25 for transporting the toner in the receiving portion 24 to a waste toner bottle (not shown), and a case 26. The upper part of the blade 21 is fixed to the blade holder 27. The blade holder 27 has both ends (both ends in a direction orthogonal to the paper surface) swingably attached to side portions 26a, 26a (only one shown) of the case 26 by shafts 27a, 27a (only one is shown). I have. A blade urging spring (compression coil spring) 28 is provided between the case 26 and the blade holder 27, and the tip of the blade 21 (the tip of the blade 21) is generated by the urging force of the blade urging spring 28 and the elastic force of the blade 21 itself. Edge) 21a
Contact the surface of the photoconductor 10.

As clearly shown in FIG. 2, the feature of this embodiment is that the above-mentioned depositing section 23 makes the contact portion C between the photoreceptor 10 and the cleaning blade 21 and the portion U just below the contact portion.
Is that the toner T scraped off by the blade 21 is constantly deposited. Deposition section 23 in this embodiment
Is formed by a surface of a photoreceptor, the rake sheet 22, and a plate-like deposition member 23b attached to the rake sheet 22 via a spacer 23a.
The spacer 23a and the stacking member 23b extend in a direction orthogonal to the paper surface, and the stacking portion 23 is provided over the entire length below the contact portion C. An interval 23d is formed between the upper end 23c of the accumulation member 23b and the blade 21. Through this interval 23d, excess toner out of the toner T accumulated on the accumulation section 23 is removed by the receiving section 24.
It overflows into.

As shown in FIG. 1, the rake sheet 22 is
It is fixed to the case 26, and the bottom of the spacer 23 a is supported by the case 26.

The above-described cleaning device is configured as a unit by a case 26, and is detachably attached to a frame (not shown) of the image forming apparatus main body.

The intermediate transfer device 30 includes a driving roller 31,
It has four driven rollers 32, 33, 34, 35, an endless intermediate transfer belt 36 as an intermediate transfer member stretched over these rollers, a secondary transfer roller 37, and a cleaning unit 38. ing.

The driving roller 31 is driven to rotate at substantially the same peripheral speed as the photosensitive member 10 by engaging a gear (not shown) fixed to the end with a driving gear (not shown) of the photosensitive member 10. Therefore, the intermediate transfer belt 36 is circulated in the direction indicated by the arrow at substantially the same peripheral speed as the photoconductor 10. The driven roller 35 is a primary transfer roller, and is pressed against the photoconductor 10 via the intermediate transfer belt 36, and forms a primary transfer portion Tr1 between the photoconductor 10 and the intermediate transfer belt 36 at the pressed portion. ing. Drive roller 31
Is provided with an electrode roller (not shown) via an intermediate transfer belt 36, and a primary transfer voltage is applied to the intermediate transfer belt 36 via the electrode roller.
The driven roller 32 is a tension roller, and urges the intermediate transfer belt 36 in the tension direction by an urging means (not shown). The driven roller 33 is a backup roller that forms the secondary transfer unit Tr2. A secondary transfer roller 37 is opposed to the backup roller 33 via an intermediate transfer belt 36. The secondary transfer roller 37 is
It can be moved toward and away from the intermediate transfer belt 36 by a contacting / separating mechanism (not shown). A secondary transfer voltage is applied to the secondary transfer roller 37. The driven roller 34 is a backup roller for the cleaning unit 38. The cleaning unit 38 is configured by an intermediate transfer member blade that comes into contact with the intermediate transfer belt 36 and scrapes off the remaining toner (secondary transfer residual toner) on the outer peripheral surface thereof. The intermediate transfer member blade can be moved toward and away from the intermediate transfer belt 36 by a contact / separation mechanism (not shown). The toner scraped off by the intermediate transfer member blade 38 is received by a receiving portion (not shown), and is conveyed to a waste toner bottle by a screw (not shown).

In the course of circulating the intermediate transfer belt 36, the toner image on the photosensitive member 10 is transferred onto the intermediate transfer belt 36 in the primary transfer section Tr1, and the toner image transferred onto the intermediate transfer belt 36 is In the secondary transfer section Tr2, the image is transferred onto a recording medium P such as a sheet to be transferred, which is supplied to the secondary transfer roller 37. Recording medium P
Is supplied from a sheet feeding device (not shown) and supplied to the secondary transfer unit Tr2 at a predetermined timing.

The operation of the entire image forming apparatus as described above is as follows. (I) When a print command signal (image forming signal) from a not-shown host computer or the like (a personal computer or the like) is input to the control unit of the image forming apparatus, the tension roller 32 operates to put the intermediate transfer belt 36 in a stretched state. Becomes
The photosensitive member 10 and the developing roller 1 are driven by driving means (not shown).
3, and the intermediate transfer belt 36 is driven to rotate. (Ii) The outer peripheral surface of the photoconductor 10 is uniformly charged by the charging roller 12. (Iii) Selectively exposing the outer peripheral surface of the uniformly charged photoconductor 10 according to image information of the first color (for example, magenta (M)) by an exposing unit (not shown),
An electrostatic latent image for magenta is formed. (Iv) The first color (for example, magenta) is applied to the photoconductor 10.
Only the developing roller 13 </ b> M comes into contact, whereby the electrostatic latent image is developed, and a toner image of the first color (for example, magenta) is formed on the photoconductor 10. (V) A primary transfer voltage having a polarity opposite to the charging polarity of the toner is applied to the intermediate transfer belt 36, and the toner image formed on the photoconductor 10 is transferred to the primary transfer unit Tr1, that is, the photoconductor 10 and the intermediate transfer belt. The toner image is transferred onto the intermediate transfer belt 36 at a pressure contact portion Tr1 with the intermediate transfer belt 36. At this time, the secondary transfer roller 37 and the cleaning unit 38 are separated from the intermediate transfer belt 36. (Vi) After the toner (primary residual toner) remaining on the photoreceptor 10 is removed by the photoreceptor blade 21, the photoreceptor 1 is discharged by discharging light from a discharging unit (not shown).
0 is eliminated. (Vii) The above operations (ii) to (vi) are repeated as necessary. That is, the second color, the third color, and the fourth color are repeated in accordance with the content of the print command signal, and the toner images corresponding to the content of the print command signal are superimposed on the intermediate transfer belt 36 to form an intermediate image. It is formed on the transfer belt 36. (Viii) The recording medium P is supplied at a predetermined timing, and immediately before or after the leading end of the recording medium P reaches the secondary transfer portion Tr2 (in short, at a desired position on the recording medium P, on the intermediate transfer belt 36). (At the timing when the toner image of the intermediate transfer belt is transferred).
6, the secondary transfer voltage is applied, and the toner image (basically a full-color image) on the intermediate transfer belt 36 is transferred onto the recording medium P. Further, the intermediate transfer member blade 38 comes into contact with the intermediate transfer belt 36, and the toner (secondary residual toner) remaining on the intermediate transfer belt 36 after the secondary transfer is removed. (Ix) The toner image is fixed on the recording medium P by passing the recording medium P through a fixing device (not shown).
The recording medium P is discharged out of the apparatus. (X) If the image forming signal is not input for a predetermined time or the power of the apparatus is turned off after the operations (i) to (ix) are performed, the tension transfer roller 36 is operated to operate the intermediate transfer belt 36 in a stretched state. Is released.

According to the above-described image forming apparatus, the following operation and effect can be obtained. The toner remaining on the image carrier 10 after the transfer of the toner image on the image carrier 10, which is a rotating body carrying the toner image, is scraped off by the cleaning blade 21 that comes into contact with the surface of the image carrier 10. Removed. According to the image forming apparatus of this embodiment, the image carrier 10 and the cleaning blade 2
The toner T scraped off by the blade 21 is always deposited on the contact portion C and the immediately lower portion U thereof, and the action of the toner T as a lubricant causes the turning of the blade 21 as described below. Is less likely to occur. In other words, since the toner T scraped off by the blade 21 is always deposited on the contact portion C between the image carrier 10 and the cleaning blade 21 and immediately below U, the rotating image carrier 10 includes:
The toner T is always supplied to the contact portion C with the cleaning blade 21 without being affected by the image pattern. Since the toner acts as a lubricant, the presence of the toner T causes the blade 21 and the image carrier 1 to move.
The frictional force with the zero surface decreases, and as a result, even when the contact pressure and / or contact angle of the blade 21 is increased, the blade 21 is less likely to be turned. Further, for the same reason, it is difficult for the blade to be turned up even in a high temperature and high humidity environment. As described above, according to the image forming apparatus of this embodiment, even when the contact pressure and / or the contact angle of the cleaning blade 21 is increased, the blade 21 is less likely to be turned. Moreover, the cleaning blade 21
Removes toner by a so-called stick-slip behavior. However, according to this image forming apparatus, the frictional force between the blade 21 and the surface of the image carrier 10 is reduced, so that the behavior is stabilized. As a result, the cleaning performance is further improved.

In the initial stage of use of the image forming apparatus (for example, when the image forming apparatus is provided to a user and started to be used),
It takes a short time, though a short time, for the toner to be deposited. However, in this type of image forming apparatus, usually, an image carrier ( A lubricant such as oil is applied to the surface of the photoreceptor or the like, or a lubricant such as polyvinylidene fluoride is applied to the surface of the blade, so that the blade is turned up even in the initial stage of use until the toner is deposited. There is no.

<Second Embodiment> FIG. 3 is an enlarged view showing a main part of an image forming apparatus according to a second embodiment of the present invention. In the figure, the same or corresponding parts as in the first embodiment are denoted by the same reference numerals.

This embodiment is different from the first embodiment in that a rake sheet 22, a spacer 23a,
This is in that the plate-like deposition member 23b is integrally formed, and there is no other difference. According to this embodiment, the same operation and effect as those of the first embodiment can be obtained. Further, since the rake sheet 22, the spacer 23a, and the plate-like deposition member 23b are integrally formed, the number of components is reduced, and the assembling property is improved.

<Third Embodiment> FIG. 4 is an enlarged view showing a main part of an image forming apparatus according to a third embodiment of the present invention. In the figure, the same or corresponding parts as in the first embodiment are denoted by the same reference numerals.

This embodiment is different from the first embodiment in that the height of the plate-like deposition member 23b is lower than that of the first embodiment. The point remains the same. As shown in FIG. 4, the height of the deposition member 23b is within a range where the toner T scraped off by the blade 21 is constantly deposited on the contact portion C between the image carrier 10 and the cleaning blade 21 and the immediately lower portion U thereof. Can be reduced. According to this embodiment, the same operation and effect as those of the first embodiment can be obtained.

<Fourth Embodiment> FIG. 5 is an enlarged view showing a main part of a fourth embodiment of the image forming apparatus according to the present invention. In the figure, the same or corresponding parts as in the first embodiment are denoted by the same reference numerals.

This embodiment is different from the first embodiment in that a rake sheet 22 and a stacking member 23b are formed by bending a single plate-like body (sheet-like body) without providing a spacer 23a. 23e) and the other points are the same. According to this embodiment, the same operation and effect as those of the first embodiment can be obtained. Also, without providing the spacer 23a, the rake sheet 22 and the stacking member 23b
One bent plate (including sheet)
Since it is formed of 23e, the number of parts is reduced and the assemblability is improved.

<Fifth Embodiment> FIG. 6A is an enlarged view showing a main part of an image forming apparatus according to a fifth embodiment of the present invention, and FIG. FIG. In FIG. 6, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals.

This embodiment is characterized in that the angle of repose of the toner T is α, and a vertical line V passing through the rotation center 11 of the image carrier 10 at a contact portion C between the image carrier 10 and the cleaning blade 21 is used as a reference. If the angle from the perpendicular V to the contact portion C is β, the direction opposite to the direction of rotation (in this case, the counterclockwise direction) of the rotation direction of the support 10 is β. In the figure, H is a horizontal line. With such a configuration, for example, the contact portion C is formed by the surface of the image carrier 10 without providing the special toner depositing member 23b provided in the first embodiment.
Further, the toner T can be deposited on the portion U immediately below the toner. If β is too small (for example, a negative value, and the contact portion C is located to the right of the vertical line V in the figure), the toner discharging property becomes extremely poor.
In some cases, there is a possibility that a defect that cleaning failure occurs may occur. Therefore, β is desirably α / 10 or more. According to this embodiment, the same operation and effect as those of the first embodiment can be obtained. Further, the toner T can be deposited on the contact portion C and the portion U immediately below the contact portion C by the surface of the image carrier 10 without providing a special toner depositing member. Is improved.

Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above-described embodiments or examples, and can be appropriately modified and implemented within the scope of the present invention. It is. For example, in the above embodiment, the case where the image carrier is a photoconductor has been described. However, the present invention is also applicable to a case where the image carrier is an intermediate transfer member. Further, in the above embodiment, the case where the image carrier (photoconductor) is cylindrical has been described, but the present invention is also applicable to the case where the image carrier is belt-shaped.

[0034]

According to the image forming apparatus of any one of claims 1 and 2, the contact pressure of the cleaning blade and / or
Alternatively, even when the contact angle is increased, the blade is less likely to be turned. Moreover, the so-called stick-slip behavior of the cleaning blade is stabilized, and as a result, the cleaning performance is further improved.

Further, according to the image forming apparatus of the present invention, the contact portion between the image bearing member and the cleaning blade and the portion directly below the contact portion by the surface of the image bearing member without providing a special toner accumulation member. Then, the toner can be deposited.

[0036]

[Brief description of the drawings]

FIG. 1 is a schematic front sectional view showing a first embodiment of an image forming apparatus according to the present invention.

FIG. 2 is an enlarged view of a main part of the same.

FIG. 3 is an enlarged view showing a main part of a second embodiment of the image forming apparatus according to the present invention.

FIG. 4 is an enlarged view showing a main part of a third embodiment of the image forming apparatus according to the present invention.

FIG. 5 is an enlarged view showing a main part of a fourth embodiment of the image forming apparatus according to the present invention.

FIG. 6A is an enlarged view showing a main part of an image forming apparatus according to a fifth embodiment of the present invention, and FIG. 6B is an explanatory diagram of a repose angle of toner.

FIGS. 7A and 7B are explanatory diagrams of a conventional technique.

[Explanation of symbols]

 T toner 10 photoreceptor (image carrier) 11 rotation center 21 cleaning blade C contact part U immediately below V perpendicular

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masahiro Maeda 3-3-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation F-term (reference) 2H034 BF01 CA04

Claims (2)

[Claims] An image bearing member, which is a rotating member for carrying a toner image, is in contact with the surface of the image bearing member, and after the toner image on the image bearing member has been transferred, remains on the image bearing member. An image forming apparatus comprising: a cleaning blade for scraping off toner that is present, wherein the toner scraped off by the cleaning blade is constantly deposited at a contact portion between the image carrier and the cleaning blade and immediately below the contact portion. An image forming apparatus comprising: 2. An angle of repose of the toner is α, and a vertical line passing through a rotation center of the image carrier at the contact portion is defined as a reference, and a direction opposite to the rotation direction of the image carrier is defined as a positive direction. 2. The image forming apparatus according to claim 1, wherein β is equal to or less than α, where β is an angle up to.