JP2000019919A - Cleaning device and image forming device provided with same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of fluidity of toner by holding lower than the ambient temp., in a cleaning device. SOLUTION: This cleaning device 17 is made so as to remove the toner remain/sticking on an image carrier surface by toner removing means, after the electrostatic latent image formed by the toner on the rotary image carrier is transferred on transfer material, and to recover by transporting the removed toner by the toner transporting means 17-6. The device is provided with heat radiating means 17-12a radiating the heat of toner transporting means, on the toner transporting means 17-6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning device for removing residual toner adhering to the surface of an image bearing member carrying an image, and an image forming apparatus, such as a copying machine or a laser beam printer, provided with the cleaning device. About.

[0002]

2. Description of the Related Art First, an image forming apparatus will be described with reference to FIG.

The image forming apparatus 20 is a four-color full-color laser beam printer, and FIG. 1 is a longitudinal sectional view showing a schematic configuration thereof.

A laser beam printer (hereinafter, referred to as an "image forming apparatus") shown in FIG. 1 has an upper digital color image reader section (hereinafter, simply referred to as "reader section") R and a lower digital color image printer section (hereinafter, simply referred to as "image forming apparatus"). The printer unit P forms a full-color image on a transfer material S on paper or the like as a recording material based on the image of the document 30 read by the reader unit R, for example.

Hereinafter, the configurations of the reader unit R and the printer unit P will be described.

The reader unit R includes a document table glass 31 on which a document 30 is placed, an exposure lamp 32 for exposing and scanning the document 30 on the document table glass 31, and a reflected light image of the document 30 exposed and scanned by the exposure lamp 32. 33, a lens 34 for condensing the reflected light image, a full-color sensor (image reading means) 35 such as a charge-coupled device (CCD) for storing the condensed reflected light image, and control described later. Video processing unit 36 as means, and storage means 37
The reflected light image is collected on the full-color sensor 35 to obtain a color-separated image signal, and the full-color sensor 35 reads the density of the reference image. The color separation image signal is supplied to an amplification circuit (not shown).
, And then processed by the video processing unit 36 and sent to the printer unit P.

In the printer section P, a drum-type electrophotographic photosensitive member (hereinafter simply referred to as "photosensitive drum" or "drum") 1 as an image carrier is a large-diameter photosensitive drum having a diameter of 180 mm, and is indicated by an arrow R1 in the drawing. Is rotatably supported. Around the photosensitive drum 1, a primary charger (corona charger) 2 as charging means for uniformly charging the surface of the photosensitive drum 1, substantially in order along the rotation direction, and image information on the photosensitive drum 1. An image exposure device 3 for forming a corresponding electrostatic latent image, a potential sensor 1 for detecting a surface potential of the photosensitive drum 1
2. a developing device 4 for storing developers (toners) of different colors for developing an electrostatic latent image formed on the photosensitive drum 1 into a visible image, and a photodetector 1 for detecting the amount of toner on the photosensitive drum 1
3. a transfer device 5 as a transfer means, a cleaning device 7 for removing the developer remaining on the photosensitive drum 1, and
A pre-exposure lamp and the like are arranged.

[0008] The image exposure apparatus 3 includes a polygon mirror 3
a, a lens 3b, a mirror 3c, etc., and polygonally converts a laser beam (light image) E from a laser output unit (not shown) modulated by a color image signal for each color separated from the reader unit R. Reflected by mirror 3a, lens 3b
Then, the image is projected onto the surface of the photosensitive drum 1 via the mirror 3c to form an electrostatic latent image corresponding to a color image signal of each color.

The developing device 4 has four developing devices 4C, 4M, 4Y, and 4K containing toners of four colors (cyan, magenta, yellow, and black), respectively. , 4K is operated in accordance with the color of the electrostatic latent image to operate the eccentric cams 24C, 24M, 24Y, 24K so as to approach the photosensitive drum 1 to perform the developing operation.

At the time of image formation in the printer section P, the photosensitive drum 1 is rotated at a rotational speed of 133 mm / sec in the direction of the arrow R1 in the drawing, the surface of the photosensitive drum 1 is first neutralized by a pre-exposure lamp, and then the primary charging is performed. The surface of the photosensitive drum 1 is uniformly charged by the unit 2, and the surface of the photosensitive drum 1 is sequentially irradiated with a laser beam E corresponding to a color image signal of each color separated by the image exposure device 3 in a predetermined color order. To form an electrostatic latent image corresponding to the color image signal.

Next, predetermined developing units 4C, 4M, 4Y, 4
K is operated in the order of cyan (C), magenta (M), yellow (C), and black (K) in a predetermined developing order to develop the electrostatic latent image on the photosensitive drum 1 and Then, a toner image using a resin as a base is sequentially formed. Here, the developing units 4C, 4M, 4Y, 4K of the developing device 4
Is configured to perform a developing operation by selectively approaching the photosensitive drum 1 in accordance with the color of the toner image by the operation of the eccentric cams 24C, 24M, 24Y, and 24K.

Since each developing device is a known two-component developing device, the description of its configuration and operation will be omitted.

Here, each developing unit 4M, 4C, 4Y, 4K
The developer used in will be described.

The magenta, cyan, yellow, and black developers, which are the color developers of the color developing units 4M, 4C, 4Y, and 4K, are a two-component developer comprising a magnetic pole carrier C and a low-melting non-magnetic toner T described later. Agent is used.

The two-component developer comprises toner T and carrier C.
(Hereinafter referred to as “T / C”) is ΔT / (T +
C) It is mixed and used at a ratio (mixing ratio) of｝ × 100 = 5%. The toner T has an external additive such as silica so as to have a negative charge, and has a diameter of about 8 μm.
m, and has a high fluidity in order to obtain high image quality, and has a charge of 3.0 × 10 ⁻² C / kg as a tribo.
The magnetic carrier C is formed of a ferrite carrier having a diameter of about 50 μm.

In forming a multi-color image or a full-color image, the toner uses a sharp-melt toner, widens the color reproduction range of a copy, and satisfactorily obtains a color copy faithful to a document. The toner is manufactured by melt-kneading, pulverizing, and classifying a toner-forming material such as a binder resin such as a polyester resin or a styrene-acryl ester resin, a colorant (a dye, a sublimable dye), and a charge control agent. You. Various external additives (for example, hydrophobic colloidal silica) are added to the toner as needed.

In consideration of the fixing property and the sharp melt property, it is particularly preferable that the color toner uses a polyester resin as the binder resin. Examples of the sharp melt polyester resin include a polymer compound having an ester bond in the main chain of a molecule synthesized from a diol compound and a dicarboxylic acid. In particular, the structural formula shown in FIG. 5 (where R is an ethylene or propylene group, X, Y
Is a positive integer of 1 or more, respectively, and the average value of X + Y is 2 to 10. ), A bisphenol derivative represented by the formula (1) or a substituted derivative thereof as a diol component, a divalent or higher carboxylic acid, an acid anhydride thereof or a lower alkyl esterified carboxylic acid (eg, fumaric acid, maleic acid, maleic anhydride, phthalic acid , Terephthalic acid, trimellitic acid, pyromellitic acid, etc.) as a carboxylic acid is more preferable because it has a sharp melting property. The softening point of the polyester resin is from 75 to 150C, preferably from 80 to 120C.

The toner or binder resin having a sharp melt property is defined as a temperature at which an apparent melt viscosity shows 10 ³ poise is T ₁ , and a temperature at which an apparent melt viscosity shows 5 × 10 ² poise is T.
When T is ₂ , T ₁ = 90 to 150 ° C. | ΔT | = | T ₁ −T ₂ | = 5 to 20 ° C.

The sharp-melt resin having these temperature-melt viscosity characteristics is characterized in that the viscosity is reduced very sharply when heated. Such a decrease in viscosity causes appropriate mixing of the uppermost toner layer and the lowermost toner layer, and at the same time, sharply increases the transparency of the toner layer itself, thereby enabling good subtractive color mixing.

Referring back to FIG. 4, the recording material cassettes 7a, 7b,
7c (in some cases, the paper is manually fed), the transfer material S fed by a transport system including a pickup roller, a paper feed guide, a paper feed roller, and the like is provided with a toner image formed on the photosensitive drum 1 at a predetermined position. Is wound around the transfer device 5 in synchronization with the timing of the transfer to the transfer device 5.

The transfer device 5 includes a transfer drum 5a having a diameter of 180 mm as a recording material carrier and a transfer charger 5b for transferring the toner image on the photosensitive drum 1 to the transfer material S.
A suction corona charger 5c serving as suction charging means for causing the transfer material S to be attracted to the transfer drum 5a; a suction roller 5g serving as a counter electrode; an inner corona charger 5d; and an outer corona charger 5e. A recording material carrying sheet 5f made of a dielectric material, which is a recording material carrying means, is integrally formed in a cylindrical shape in a peripheral opening area of the transfer drum 5a, which is rotatably supported and provided with a separating charger 5h. It is stretched. In the transfer device 5, two sheets of transfer paper S of A4 size or the like,
One transfer material S having a size or the like can be supported.
The image formation on the two transfer materials S is performed by continuously irradiating the same image signal, continuously forming a toner image on the photosensitive drum 1, and performing transfer. As the recording material supporting sheet 5f, a dielectric sheet such as a polycarbonate film is used.

The transfer drum 5a is rotated in the direction indicated by an arrow R5 in synchronization with the photosensitive drum 1, and the cyan toner image developed by the cyan developing device 4C is transferred to a transfer portion (contact portion between the photosensitive drum 1 and the transfer drum 5a) N In the above, the image is transferred onto the transfer material S carried on the recording material carrying sheet 5f by the transfer charger 5b. The transfer drum 5a continues to rotate as it is, and prepares for transfer of a toner image of the next color (for example, magenta).

The photosensitive drum 1 on which the toner image has been transferred
The cleaner 7 having the cleaning blade 71 cleans the deposits such as residual toner.

Here, the cleaning device 7 in FIG. 4 will be described.

The toner is transferred from the photosensitive drum 1 to the transfer material by the transfer charger 5b shown in FIG. 4, but partially remains on the photosensitive drum 1 and remains as residual toner T, and is conveyed by the photosensitive drum 1. Is done. The residual toner must be collected by the cleaning device 7 before moving to the next step.

FIG. 6 is a schematic diagram of the cleaning device 7. The cleaning device 7 is disposed at a position where it contacts the photosensitive drum 1 rotating in the direction of arrow R1. The cleaning device 7 has a cleaning blade 71 formed by flowing and bonding an elastic rubber blade 7-1a such as urethane rubber to a supporting metal plate 7-1b. The cleaning blade 71 is pressed against the surface of the photosensitive drum 1 by the spring force of a tension coil spring 7-5 stretched between the cleaning container 7-9 and the support member 7-4. At the transfer portion, residual toner T remaining on the surface of the photosensitive drum 1 without contributing to the transfer reaches the cleaning device 7 and is scraped off by the cleaning blade 71. Thereafter, the residual toner T scraped off on the squeeze sheet 7-7 is
The toner is sent to a toner conveying screw 7-6 via a toner stirring spring 7-8.

As shown in FIG. 7, the rotary shaft 7-12 of the toner conveying screw 7-6 is directly connected to a motor M. When the motor M is rotated, a spiral shape is formed on the rotary shaft 7-12. , And rotates integrally with the feed blade 7-13 provided in the control unit. As a result, the toner is transported to the waste toner box 7-11.

The photosensitive drum 1 on which the toner image has been transferred
Is uniformly charged again by the primary charger 2 and receives the above-described image exposure to the laser beam E modulated by the next magenta image signal. The magenta latent image is developed by a magenta developing device 4M to form a magenta toner image, and the magenta toner image is transferred to a transfer material S carried on a recording material carrying sheet 5f at a transfer section N, and the cyan image is formed. A magenta toner image is superimposed and transferred on the toner image. Further, the transfer drum 5a continues to rotate as it is,
Prepare for transfer of a toner image of the next color (for example, yellow).

The above process is repeated to form and transfer yellow and black images, and when the transfer of the toner images of four colors is completed, the transfer material S is separated by the separating charger 5h which performs an AC corona discharge. The charge is removed, and then separated from the transfer drum 5a by the action of the separation push-up roller 8b and the separation claw 8a.
, And are collectively fixed and discharged onto an external paper discharge tray 10.

[0030]

However, the conventional cleaning device has the following problems.

In FIGS. 4, 6 and 7, the waste toner collected by the cleaning blade 71 is carried by the toner conveying screw 7-6 as described above.

At this time, if the temperature and humidity around the cleaning device 7 are low, the waste toner is smoothly conveyed and finally discharged from the waste toner discharge port 7-10, and the waste toner box 7-11. Will be collected.

However, when the temperature and humidity are high, the waste toner has poor fluidity, and the toner conveying screw 7-6
And the toner is hardly conveyed, and stays around the toner conveying screw 7-6 and the toner stirring spring 7-8. Finally, the waste toner is removed from the cleaning container 7.
-9, the cleaning device 7 may become defective, may fall off the squeeze sheet 7-7, and may adhere to the transfer material and cause image formation failure, or may adhere to other parts. This may cause a malfunction of the image forming apparatus.

In recent years, such phenomena have become remarkable due to low melting and sharp melting of the toner under the condition of colorization and high speed of the image forming apparatus. I have. Above all, in the case of colorization, the melting point of the toner is an indispensable technique in order to fuse and fix the toner in a mixed color, and the above problem is likely to occur.

Further, an organic photoreceptor is often used for the photoreceptor drum, and in this photoreceptor, a nitric acid compound formed by the reaction of ozone generated in the surroundings in the air is deposited, and the photoreceptor easily causes an electric flow. Become. In order to solve such a phenomenon, a drum heater (not shown) is provided in the photosensitive drum, and the surface of the photosensitive drum is heated to, for example, about 40 degrees C.
The water on the surface of the photosensitive drum is evaporated to prevent the flow of electricity. At this time, if only the temperature of the drum heater, the temperature around the cleaning device does not rise so much, but the temperature around the cleaning device rises due to the heat from other heating elements around the device, and the temperature inside the cleaning device rises. The fluidity of the waste toner was reduced, and the above problem was likely to occur.

Incidentally, the temperature and humidity at which the fluidity of the waste toner deteriorates are uniquely determined by the composition formula of the toner used in each image forming apparatus and the rotational speed and shape of the toner conveying screw 7-6. However, the temperature is about 50 degrees or more and the humidity is about 50% or more.

The present invention provides a cleaning device for maintaining the temperature lower than the ambient temperature to prevent deterioration of toner fluidity, and an image forming apparatus including the cleaning device and capable of performing high-quality image processing. The purpose is to do.

[0038]

The above object is achieved by the following means.

After the electrostatic latent image formed by the toner on the surface of the rotatable image carrier is transferred to the transfer material, the toner remaining on the surface of the image carrier is removed by toner removing means. A cleaning device for transporting and removing the removed toner by a toner transport unit, wherein the toner transport unit is provided with a heat radiating unit for releasing heat of the toner transport unit.

The toner conveying means is a toner conveying screw having a spiral feed blade around a metal rotary shaft.

The heat radiating means is a heat radiating shaft formed by extending an end of the rotary shaft.

The radiating means is a metal radiating fin radially provided on the rotating shaft.

The radiating fins are disposed in an air duct through which air flows.

[0044] The heat radiating means is provided integrally with a heat radiating shaft formed by extending an end of the rotary shaft, and is a rotating body having a larger diameter than the heat radiating shaft.

[0045] The rotating body is a gear for transmitting a rotating force to the rotating shaft.

An image forming apparatus comprising: an image forming means for transferring an electrostatic latent image formed by toner on the surface of an image carrier to a transfer material; and the cleaning device according to any one of the above. apparatus.

(Operation) The toner removed by the toner removing means of the cleaning device is collected and transported by the toner transporting means. Since the toner conveying means is provided with the heat radiating means, even if the ambient temperature rises, the heat does not remain, and the fluidity of the waste toner does not deteriorate.

Therefore, the waste toner is smoothly discharged.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

The structure of the image forming apparatus in which the cleaning device described below is incorporated is substantially the same as that of the image forming apparatus shown in FIG. 4, and the description of the structure and operation will be omitted.

In the cleaning device described below, the same components as those of the cleaning device shown in FIG. 7 are denoted by the same reference numerals as those shown in FIG. 7, and the description of those portions is omitted. . Therefore, as for the cleaning device, only portions different from the cleaning device shown in FIG. 7 will be described.

(First Embodiment) A metal rotary shaft 17-12 of a toner conveying screw 17-6 of a cleaning device 17 shown in FIG. It is connected. Rotary shaft 17-12
The extended portion forms a heat radiation shaft 17-12a. By the way, the radiation shaft 17-12a is connected to the cleaning container 7-
It protrudes from 50 by about 50 mm.

Accordingly, the radiation shaft 17- is connected to the rotation shaft 17-12.
12a, the rotating shaft 17-12 and the radiating shaft 17-12a are made of metal, and the toner conveying screw 17-6 is separated from the heat source such as the motor M and the photosensitive drum. The heat in the container 7-9 is
The heat is radiated from the radiation shaft 17-12a, and the toner conveying screw 17-12 is not affected by the heat source.

Therefore, the cleaning device 17 shown in FIG.
It is possible to prevent deterioration of the fluidity of the waste toner in the cleaning container 7-9 by preventing heat from being trapped in the cleaning container 7-9 and lowering the temperature of the rotating shaft 17-12 itself compared with other portions. This is advantageous in that waste toner can be prevented from adhering to the feed blades 7-13.

Incidentally, the temperature inside the cleaning container 7-9 is about 50 degrees, and the temperature of the toner conveying screw 17-6 is about 47 degrees.

(Second Embodiment) The metal rotary shaft 27-12 of the toner conveying screw 27-6 of the cleaning device 27 shown in FIG. 2 also extends outside the cleaning container 7-9 and is connected to the motor M. It is connected. Rotary shaft 27-12
The extended portion forms a heat radiation shaft 27-12a. On the radiating shaft 27-12a, four metal flat radiating fins 27-14 are radially projected at equal intervals.
By the way, the radiation fin 27-14 is a radiation shaft 27-12a.
The length of the part to be attached to is about 30 mm, and the protruding length is about 10 mm. The heat radiation fins 27-14 are located in the air duct 27-15 through which air flows.

Therefore, the radiation shaft 27- is connected to the rotation shaft 27-12.
12a, radiation fins 27-14 on the radiation shaft 27-12a, radiation fins 27-1
4 is disposed in the air duct 27-15, the rotation shaft 27-12, the radiation shaft 27-12a, and the radiation fin 2
7-14 is made of metal, and the toner conveying screw 2
The heat in the cleaning container 7-9 is radiated from the heat radiating shaft 27-12a and the heat radiating fins 27-14, and the toner in the cleaning container 7-9 is separated from the heat source such as the motor M and the photosensitive drum. The transport screw 27-12 is no longer affected by the heat source.

Therefore, the cleaning device 27 shown in FIG.
It is possible to prevent deterioration of the fluidity of the waste toner in the cleaning container 7-9 by preventing the heat from being trapped in the cleaning container 7-9 and lowering the temperature of the rotating shaft 27-12 itself compared with other portions. This is advantageous in that waste toner can be prevented from adhering to the feed blades 7-13.

(Third Embodiment) The metal rotary shaft 37-12 of the toner conveying screw 17-6 of the cleaning device 37 shown in FIG. 3 extends outside the cleaning container 7-9. The extended part is the radiation shaft 37-12a.
It has become. A driven gear 37-18 is provided at the tip of the heat radiation shaft 37-12a. Driven gear 37-1
8 meshes with a driving gear 37-19 rotated by a motor.

Accordingly, the radiation shaft 37- is connected to the rotation shaft 37-12.
12a, a heat dissipating shaft 37-12a, a driven gear 37-18, a rotating shaft 37-12, a heat dissipating shaft 37-12a, and a driven gear 37-18, made of metal, Since the screw 37-6 is separated from the heat source such as the motor M and the photosensitive drum, the heat in the cleaning container 7-9 is radiated from the heat radiation shaft 37-12a and the toner conveying screw 37-12.
Are no longer affected by the heat source.

The driven gear 37-18 is provided with a radiation shaft 37-12.
a, which are formed integrally and have a larger diameter than the radiation shaft 37-12a.

Therefore, the cleaning device 37 shown in FIG.
The deterioration of the fluidity of the waste toner in the cleaning container 7-9 is prevented by, for example, preventing the heat from being trapped in the cleaning container 7-9 and the temperature of the rotating shaft 37-12 itself being lower than the other portions. This is advantageous in that waste toner can be prevented from adhering to the feed blades 7-13.

Further, the cleaning device 37 shown in FIG.
Since the driven gear 37-18 meshes with the driving gear 37-19, heat is transmitted between the two gears, and the heat in the cleaning container 7-9 can be radiated by the heat transmission.

In general, it is conceivable to use a fan when lowering the temperature of an object. However, if a fan is provided in the cleaning devices 17, 27, and 37, the toner may be scattered because the toner is a powder, and the fan cannot be used. Therefore, the configuration that prevents the temperature rise of the cleaning device due to heat radiation or heat transfer without using a fan as in the present invention is an optimal configuration in the image forming apparatus.

[0065]

According to the cleaning device of the present invention, the heat of the cleaning device itself is released by the heat radiating means so that the cleaning device is hardly affected by the ambient temperature. Is prevented from adhering to the toner, and the toner can be smoothly transported and collected.

The toner is a powder, and the toner may be scattered when the cleaning device is cooled by a fan. However, if the temperature is prevented from rising by the heat radiation by the heat radiation means as in the cleaning device of the present invention, the toner is scattered. The temperature can be lowered without scattering.

Further, since the toner can be smoothly conveyed and collected, it is possible to prevent the toner from falling down.
The transfer material is not contaminated and other devices do not malfunction.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a cleaning device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of a cleaning device according to another embodiment.

FIG. 3 is a cross-sectional view illustrating a schematic configuration of a cleaning device according to another embodiment.

FIG. 4 is a cross-sectional view illustrating a schematic configuration of the image forming apparatus.

FIG. 5 is a diagram illustrating a structural formula of a toner.

FIG. 6 is a cross-sectional view in the width direction of a conventional cleaning device.

FIG. 7 is a cross-sectional view illustrating a schematic configuration of another cleaning device.

[Explanation of symbols]

T toner S transfer material 1 photosensitive drum (image carrier) 3 exposure device (image forming device) 4 developing device (image forming device) 5 transfer device (image forming device) 7-7 squeeze sheet (toner removing device) 17, 27, 37 Cleaning Device 17-6, 27-6, 37-6 Toner Conveying Screw (Toner Conveying Means) 17-12, 27-12, 37-12 Rotary Shaft 17-12a, 27-12a, 37-12a Radiating Shaft 17- 13 feed blade 20 image forming apparatus 27-14 heat radiation fin 27-15 air duct 37-18 driven gear (rotary body)

Claims (8)

[Claims] After an electrostatic latent image formed by toner on a rotatable image carrier surface is transferred to a transfer material, toner remaining on the image carrier surface is removed by toner removing means. A cleaning device that conveys and removes the removed toner by a toner conveying unit, wherein the toner conveying unit is provided with a heat radiating unit that releases heat of the toner conveying unit. 2. The cleaning device according to claim 1, wherein the toner conveying means is a toner conveying screw provided with a spiral feed blade around a metal rotary shaft. 3. The cleaning device according to claim 2, wherein the heat radiating means is a heat radiating shaft formed by extending an end of the rotating shaft. 4. The cleaning device according to claim 2, wherein the heat radiating means is a metal radiating fin radially provided on the rotating shaft. 5. The cleaning device according to claim 4, wherein the radiating fin is disposed in an air duct through which air flows. 6. The heat dissipating means according to claim 2, wherein the heat dissipating means is provided integrally with a heat dissipating shaft formed by extending an end of the rotary shaft, and is a rotating body having a larger diameter than the heat dissipating shaft. Cleaning device. 7. The cleaning device according to claim 6, wherein the rotating body is a gear that transmits a rotating force to the rotating shaft. 8. An image forming means for transferring an electrostatic latent image formed by toner on the surface of the image carrier to a transfer material, and the cleaning device according to claim 1. An image forming apparatus comprising: