JP2003241598A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which prevents toner scatter and forms a stable image, in a toner recycle system. <P>SOLUTION: In the image forming apparatus having: a toner recycle means 80 which transports toner, recovered by a cleaning means 63, to a developing means 61 as a recycled toner, thereby using the toner again; and a scattered toner quantity detecting means 101 which detects a quantity of toner scattered from the developing means, there is provided a control means which controls, based upon the result of the detection by the scattered toner quantity detecting means, a quantity of recycled toner which is transported from the toner recycle means to the developing means. <P>COPYRIGHT: (C)2003,JPO

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 an electrophotographic copying machine, a printer and a facsimile, and more particularly to an image forming apparatus using a toner recycling method.

[0002]

2. Description of the Related Art In recent years, an increasing number of image forming apparatuses have adopted a toner recycling system in which toner collected by a cleaning means is reused in order to effectively utilize resources and protect environmental problems. However, when the collected recycled toner is returned to the developing unit to form an image, there is a problem that a problem such as background stain occurs. Therefore, in the image forming apparatus that performs toner recycling, based on the background stain on the image carrier detected by the image density sensor on the image carrier, the ratio of unused toner and recycled toner is controlled,
A technique for reducing the above problems is disclosed in Japanese Patent Laid-Open No. 9-281
It is disclosed in Japanese Patent No. 783.

However, in the conventional image forming apparatus, when the ratio of the recycled toner to the unused toner in the developer is increased, not only the background of the image is smeared but also the toner is scattered to cause the charging means in the apparatus. However, there is a problem that the developing process elements such as the developing unit, the image carrier, and the transfer unit are contaminated, which causes various deterioration of image quality.

[0004]

SUMMARY OF THE INVENTION Therefore, the present invention provides an image forming apparatus which solves the above-mentioned conventional problems and can prevent toner scattering in a toner recycling system to form a stable image. The purpose is to do.

[0005]

In order to achieve the above object, the invention of claim 1 is a toner recycling means for conveying the toner collected by the cleaning means as recycling toner to the developing means for reuse and a developing means. In an image forming apparatus provided with a toner scattering amount detecting means for detecting the amount of toner scattering from the toner, a control means for controlling the carrying amount of recycled toner carried from the toner recycling means to the developing means based on the detection result of the toner scattering amount detecting means. It is characterized by having.

According to a second aspect of the present invention, in the first aspect, the control means controls the ratio of the unused toner and the recycled toner conveyed to the developing means based on the detection result of the toner scattering amount detection means. And According to a third aspect of the present invention, in the first or second aspect, the control unit reduces the transport amount of the recycled toner to the developing unit when the toner scattering amount detected by the toner scattering amount detecting unit exceeds a predetermined amount. , Or not transported. According to a fourth aspect of the present invention, in any one of the first to third aspects, the control unit controls the transport amount of the recycled toner transported to the developing unit per hour based on the detection result of the toner scattering amount detection unit. Characterize.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a tandem type indirect transfer type electrophotographic apparatus (color copying machine). Reference numeral 1 in the figure
Reference numeral 00 is a copying apparatus main body, 200 is a sheet feeding table on which the copying apparatus is placed, 300 is a scanner mounted on the copying apparatus main body 100, and 400 is an automatic document feeder (ADF) further mounted thereon.

An endless belt-shaped intermediate transfer member 10 is provided at the center of the copying apparatus main body 100. Intermediate transfer member 10
As shown in the cross section in FIG. 2, a base layer 11 is made of a fluororesin having a small elongation or a rubber material having a large elongation, and a base layer made of a material which does not easily grow such as canvas is formed on the base layer 11. ing. The elastic layer 12 is made of, for example, fluorine rubber or acrylonitrile-butadiene copolymer rubber. The surface of the elastic layer 12 is coated with, for example, a fluororesin to form a coating layer 1 having good smoothness.
Covered with 3.

As shown in FIG. 1, the intermediate transfer member 10 is wound around three supporting rollers 14, 15 and 16 in the illustrated example and can be rotated and conveyed clockwise in the drawing. In this illustrated example, the second support roller 15 among the three rollers is used.
An intermediate transfer member cleaning device 17 for removing the residual toner remaining on the intermediate transfer member 10 after the image transfer is provided on the left side of. An intermediate transfer body 10 is stretched between the first support roller 14 and the second support roller 15, and four intermediate transfer bodies 10 of yellow, cyan, magenta, and black are arranged along the transport direction. The image forming units 18 are arranged side by side to form a tandem image forming apparatus 20.

An exposure device 21 is further provided on the tandem image forming apparatus 20, as shown in FIG. On the other hand, the tandem image forming apparatus 20 with the intermediate transfer member 10 interposed therebetween.
A secondary transfer device 22 is provided on the opposite side. Two
The secondary transfer device 22 is configured by a secondary transfer belt 24, which is an endless belt, is stretched between two rollers 23, and is arranged by being pressed against the third support roller 16 via the intermediate transfer body 10. The image on 10 is transferred onto a sheet. Next to the secondary transfer device 22, a fixing device 25 that fixes the transferred image on the sheet is provided. The fixing device 25 is configured by pressing a pressure roller 27 against a fixing belt 26 which is an endless belt. Secondary transfer device 22
Also has a sheet conveying function for conveying the sheet after the image transfer. Of course, a transfer roller or a non-contact charger may be arranged as the secondary transfer device 22, and in such a case, it is difficult to additionally provide this sheet conveying function. In the illustrated example, a sheet reversing device 28 for reversing the sheet so as to record images on both sides of the sheet under the secondary transfer device 22 and the fixing device 25 in parallel with the tandem image forming device 20 described above. Is provided.

FIG. 3 shows the tandem image forming apparatus 2 shown in FIG.
It is an enlarged view near 0. In the drawing, each image forming unit 18 of the tandem image forming apparatus 20, each photoconductor 40 of the image forming unit 18, each developing device 61, each photoconductor cleaning device 63, and the photoconductor 4 of each image forming unit 18.
0 is attached to each of the primary transfer devices 62 facing each other, and BK is attached to black, Y is attached to yellow, M is attached to magenta, and C is attached to cyan. Show.

FIG. 4 is an enlarged view of the vicinity of the image forming means 18. Of the parts constituting the image forming unit 18, the charging device 60 is formed in a roller shape in the illustrated example,
The photoconductor 40 is charged by contacting with and applying a voltage. Of course, it is also possible to perform charging with a non-contact scorotron charger. The developing device 61 may use a one-component developer, but in the illustrated example, a two-component developer including a magnetic carrier c and a non-magnetic toner is used. Then, the agitating portion 66 that conveys the two-component developer while stirring and supplies and attaches the two-component developer to the developing sleeve 65.
And a developing section 67 that transfers the toner of the two-component developer attached to the developing sleeve 65 to the photoconductor 40, and the stirring section 66 is located at a position lower than the developing section 67. The stirring unit 66 is provided with two parallel screws 68. The two screws 68 are separated by a partition plate 69 except both ends. A toner concentration sensor 71 is attached to the developing case 70.

A potential sensor 103 for detecting the potential of the surface of the photoconductor 40 is arranged between the charging device 60 and the developing device 61, and scattered from the developing device 61 between the developing device 61 and the primary transfer device 62. A toner scattering detection device 101 for detecting toner and an image density sensor 102 for detecting the image density of an image density patch (not shown) formed on the photoconductor 40 are arranged. In this embodiment, the toner scattering detection device 101 is arranged on the downstream side of the developing device 61 to detect the toner scattering to the image density sensor 102, the intermediate transfer belt 10 and the like, but is arranged on the upstream side to detect the potential sensor 103 and the like. The toner scattering to the charging device 60 or the like may be detected.

On the other hand, the developing device 61 is provided with a developing sleeve 65 facing the photoconductor 40 through the opening of the developing case 70, and a magnet 72 is fixedly provided in the developing sleeve 65. Further, a doctor blade 73 is provided so that its tip approaches the developing sleeve 65. In the illustrated example, the distance between the doctor blade 73 and the developing sleeve 65 at the closest position is set to 500 μm.

Then, the two-component developer is replaced by two screws 6
It is conveyed and circulated while being stirred at 8, and supplied to the developing sleeve 65. The developer supplied to the developing sleeve 65 is drawn up and held by the magnet 72 and forms a magnetic brush on the developing sleeve 65. Magnetic brush is developing sleeve 6
Along with the rotation of 5, the doctor blade 73 cuts the ear into a proper amount. The developer that has been cut off is stirred by the stirring unit 66.
Returned to.

On the other hand, of the developer on the developing sleeve 65, toner is transferred to the photoconductor 40 by the developing bias voltage applied to the developing sleeve 65, and the electrostatic latent image on the photoconductor 40 is visualized. After the visible image is formed, the developer remaining on the developing sleeve 65 is separated from the developing sleeve 65 and returns to the stirring section 66 in the absence of the magnetic force of the magnet 72. Further, the toner replenishment amount is determined based on the result of detecting the toner density in the developer by the toner density sensor 71 and the result of detecting the image density of the internal pattern formed on the photoconductor 40 by the image density detection sensor 102. Then, the toner is replenished to the stirring unit 66.

Incidentally, in the illustrated example, the linear velocity of the photoconductor 40 is 200 mm / s and the linear velocity of the developing sleeve 65 is 240 mm / s. The diameter of the photoconductor 40 is 50 mm, the developing sleeve 6
The developing process is performed with the diameter of 5 being 18 mm. The charge amount of the toner on the developing sleeve 65 is -10 to -30 μC /
A range of g is preferred. Photoconductor 40 and developing sleeve 65
The development gap G _P, which is the gap between the
It can be set in the range of mm to 0.4 mm, and it is possible to improve the developing efficiency by reducing the value.

The thickness of the photoconductor 40 is 30 μm, and the optical system
Beam spot diameter of 50 × 60 μm, light intensity of 0.47
It is set to mW. In addition, the photoreceptor 40 is charged (before exposure) with electricity.
Rank V ₀Is -700V, potential V after exposure_LIs -120V
The developing bias voltage to -470V, that is, the developing potential.
And the developing process is performed at 350 V.

Next, the primary transfer device 62 has a roller shape,
The intermediate transfer body 10 is sandwiched and pressed against the photoconductor 40. Other than the roller shape, a conductive brush shape or a non-contact corona charger may be used.

The photoconductor cleaning device 63 is provided with a cleaning blade 75 whose tip is pressed against the photoconductor 40 and is made of polyurethane rubber, for example. A contact brush is also used on the outer periphery of the photoconductor 40 in order to improve the cleaning property. In this explanatory view, a fur brush 76 having a conductive outer periphery is provided on the photoconductor 40 so as to be rotatable in the arrow direction. Further, a metal electric field roller 77 for applying a bias to the fur brush 76 is rotatably provided in the arrow direction, and the tip of the scraper 78 is pressed against the electric field roller 77. A toner recovery amount detection sensor 104 for detecting the recovery amount of the removed toner;
A recovery screw 79 for recovering the removed toner is provided.

Then, the fur brush 76 rotating in the counter direction with respect to the photoconductor 40 removes the residual toner on the photoconductor 40. The toner adhering to the fur brush 76 is removed by the electric field roller 77 to which a bias is applied, which contacts the fur brush 76 in the counter direction and rotates. The toner attached to the electric field roller 77 is scraped by the scraper 7.
It is cleaned at 8. Photoconductor cleaning device 63
The toner collected in (1) is moved to one side of the photoconductor cleaning device 63 by the recovery screw 79, and is returned to the developing device 61 by the toner recycling device 80 described later for reuse.

The static eliminator 64 is, for example, a lamp and irradiates light to initialize the surface potential of the photoconductor 40. And
As the photoconductor 40 rotates, the surface of the photoconductor 40 is first uniformly charged by the charging device 60, and then the laser or L light is emitted from the exposure device 21 according to the contents read by the scanner 300.
The writing light L from the ED or the like is irradiated to form an electrostatic latent image on the photoconductor 40. After that, toner is attached by the developing device 61 to visualize the electrostatic latent image, and the visible image is transferred onto the intermediate transfer body 10 by the primary transfer device 62. The surface of the photoconductor 40 after the image transfer is cleaned by the photoconductor cleaning device 63 to remove the residual toner, and the charge is removed by the charge removing device 64 to prepare for another image formation.

5 and 6 show the toner recycling device 8
It is an enlarged view which shows 0. As shown in FIG. 5, the pin 8 is provided at one end of the recovery screw 79 of the photoconductor cleaning device 63.
The roller portion 82 having the number 1 is provided. Roller part 8
2 is hooked on one side of the belt-shaped collected toner conveying member 83 of the toner recycling device 80, and the pin 81 is inserted into the elongated hole 84 of the collected toner conveying member 83. Blades 85 are provided on the outer periphery of the collected toner conveying member 83 at regular intervals, and the other side is hooked on a roller portion 87 of a rotating shaft 86.

The collected toner carrying member 83 is put in a carrying path case 88 shown in FIG. The transport path case 88 is formed integrally with the cartridge case 89, and one of the two screws 68 of the developing device 61 described above is inserted into the end portion on the developing device 61 side. Then, the driving force is transmitted from the outside to rotate the recovery screw 79, and the recovery toner transfer member 83 is rotationally transferred,
As a result, the toner collected by the photoconductor cleaning device 63 is transported to the developing device 61 through the transport path case 88, and is put into the developing device 61 by the rotation of the screw 68. After that, as described above, the two screws 68 carry and circulate while stirring together with the developer already in the developing device 61, supply it to the developing sleeve 65 and cut off the ears with the doctor blade 73, Transferred to the photoconductor 4
Develop the latent image on 0.

Next, the outline of the electrical equipment control system will be described with reference to FIG. A CPU 145 that performs arithmetic control processing, a ROM 146 that stores a basic program for arithmetic control processing and data for the processing, various sensors and detection devices (71, 101, 102, 103, 104, 143,
144), the image forming counter 151, the leaving time timer 15
A control unit 148 having a RAM 147 for fetching data such as 2 is provided, and the control unit 148 controls the operations of the copying apparatus main body 100, the paper feed table 200, the scanner 300, the automatic document feeder 400, and the like. It Therefore, an external device or the like is connected to the CPU 145 via the I / O interface 149. That is, on the input side of the I / O interface 149, the toner density sensor 71, the toner scattering amount detection device 101, the potential sensor 103, the image density sensor 102, the collected toner amount detection sensor 104, the black toner cartridge detection optical sensor 143, The color toner cartridge detecting optical sensor 144, the fixing temperature detecting sensor 150, the image forming number counter 151, and the leaving time timer 152 are connected.
Further, on the output side of the I / O interface, a developing bias control drive unit 153, a charging control drive unit 154, a toner replenishment control unit 155, a collected toner conveyance drive unit 156, a laser issuing drive unit 157, a developing roller drive unit 158, a developing revolver. The drive unit 159 and the photoconductor drive unit 160 are connected to each other.

Next, the operation will be described. When making a copy using this color electrophotographic apparatus, the automatic document feeder 40
A document is set on the document table 30 of 0. Alternatively, the automatic document feeder 400 is opened, and a document is set on the contact glass 32 of the scanner 300.
Close 0 and hold it down.

When a start switch (not shown) is pressed, when the original is set on the automatic document feeder 400, the original is conveyed and moved onto the contact glass 32, and then the original is set on the contact glass 32. Immediately, the scanner 300 is driven and the first
The traveling body 33 and the second traveling body 34 travel. Then, the light is emitted from the light source by the first traveling body 33, and the reflected light from the document surface is further reflected and directed to the second traveling body 34, and is reflected by the mirror of the second traveling body 34 to form the imaging lens 35.
The reading sensor 36 is passed through the reading sensor 36, and the contents of the document are read by this.

When the start switch is pressed, one of the support rollers 14, 15, 16 is rotationally driven by a drive motor (not shown), the other two support rollers are driven to rotate, and the intermediate transfer member 10 is rotationally conveyed. . At the same time, the photoconductors 40 are rotated by the individual image forming means 18, and the black, yellow, magenta, and
A cyan monochromatic image is formed. And the intermediate transfer member 10
Along with the conveyance, the single color images are sequentially transferred to form a composite color image on the intermediate transfer body 10.

On the other hand, when the start switch is pressed, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, and the paper feed cassettes 4 provided in the paper bank 43 in multiple stages.
The sheet is unwound from one of the four and separated by the separation roller 45.
The sheets are separated one by one and placed in the paper feed path 46, and the transport roller 47
Is guided to the paper feed path 48 in the main body 100 of the copying machine, abutted against the registration rollers 49, and stopped.
Alternatively, the paper feed roller 50 may be rotated so that the manual feed tray 51
The upper sheet is fed out, separated one by one by the separation roller 52, put into the manual paper feed path 53, and also abutted against the registration roller 49 and stopped.

Then, the registration roller 49 is rotated in synchronism with the composite color image on the intermediate transfer member 10, the sheet is fed between the intermediate transfer member 10 and the secondary transfer device 22, and the secondary transfer device 22 is operated. A color image is recorded on the sheet by being transferred. The sheet after the image transfer is conveyed by the secondary transfer device 22 and sent to the fixing device 25, and the fixing device 25 applies heat and pressure to fix the transferred image, and then the switching claw 55 is switched. The sheet is discharged by the discharge roller 56 and is stacked on the sheet discharge tray 57.
Alternatively, the sheet is turned over by the switching claw 55.
Then, the image is recorded on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56.

The intermediate transfer body 10 after the image transfer is the intermediate transfer body cleaning device 17, and the intermediate transfer body 10 is transferred after the image transfer.
The residual toner remaining on the top is removed, and the tandem image forming apparatus 20 prepares for another image formation. Here, the registration roller 49 is generally grounded and used in many cases, but it is also possible to apply a bias to remove paper dust from the sheet.

The control of the recycled toner carrying amount in the above operation will be described with reference to the flow of the recycled toner carrying amount control shown in FIG. The toner density in the developer is detected by the toner density sensor 71 in S1 and the image density of the internal pattern formed on the photoconductor 40 is detected by the image density detection sensor 102. After the replenishment amount is determined, the amount of collected toner in the toner collecting device is detected by the collected toner amount detection sensor 104 in S2, and it is checked whether or not there is a certain amount of collected toner (collected toner amount threshold value). Here, the collected toner amount threshold value is an amount by which the collected toner can be stably conveyed into the developing device 61, and it is desirable that the collected screw 79 is covered with the collected toner.

If it is determined that the collected toner amount is smaller than the collected toner amount threshold value, the process proceeds to S5, where the recycled toner carrying amount is determined to be 0 (no recycled toner is carried), and the toner replenishing amount is all unused. Replenish with toner. By doing so, it is possible to prevent the toner density from decreasing without supplying the required amount of recycled toner into the developing device 61.

If it is determined that the collected toner amount is larger than the collected toner amount threshold value, the process proceeds to S3, where the toner scattering amount detection result by the toner scattering amount detecting device 101 is used as an input value.
The recycled toner supply coefficient r is calculated from the recycled toner supply coefficient table shown in FIG. Here, the recycle toner replenishment coefficient r
Is controlled by the controller 148 so that the amount of toner scattering due to the use of recycled toner is reduced.

Next, the recycled toner carrying amount and the unused toner carrying amount are determined in S4 based on the recycled toner supply coefficient obtained in S3. Here, the recycled toner conveyance amount is calculated by the product of the toner supply amount and the recycled toner supply coefficient obtained in S3. The unused toner carrying amount is calculated by subtracting the recycled toner carrying amount from the toner supply amount.

After the unused toner amount and the recycled toner amount are determined in this way, if the recycled toner replenishment coefficient is low (that is, the toner scattering amount is large), per unit time according to the table shown in FIG. The amount of recycled toner conveyed is reduced, the replenishment time is lengthened, and the calculated recycled toner is slowly conveyed to the developing means 61. By using this method, the ratio of the recycled toner mixed with the unused toner is always constant, and the toner scattering is reduced because the toner is sufficiently stirred and mixed.

It is needless to say that the present invention is not limited to the above-mentioned embodiments, and various modifications and substitutions can be made within the scope of the claims.

[0038]

According to the first aspect of the invention, since the amount of recycled toner conveyed can be controlled in accordance with the amount of toner scattering in the toner recycling system, the amount of toner scattered can be controlled by the amount of recycled toner conveyed, that is, toner scattering is prevented. Therefore, there is an effect that a stable image can be formed. Further, since a large amount of recycled toner can be conveyed when the amount of scattered toner is small, there is an advantage that the recycled toner can be effectively used.

According to the second aspect of the present invention, since the control of the amount of recycled toner conveyed is controlled by the ratio of the unused toner and the recycled toner conveyed to the developing means, it is possible to control the amount of recycled toner conveyed with higher accuracy. There is an effect.

According to the third aspect of the present invention, when the amount of scattered recycled toner is large, the amount of recycled toner that easily scatters toner is reduced or not carried when the amount of scattered toner is large. There is an effect that can be done. According to the invention of claim 4, since the amount of recycled toner conveyed per unit time can be controlled according to the amount of toner scattered, when the amount of scattered toner is large, the amount of recycled toner conveyed per unit time is reduced, and the developing unit is slowly moved. It becomes possible to convey recycled toner. By doing so, the recycled toner can be sufficiently agitated by the developing unit and sufficiently mixed with the unused toner, so that the amount of toner scattering can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic view of a tandem-type indirect transfer type electrophotographic apparatus showing an embodiment of the present invention.

FIG. 2 is a sectional view of an intermediate transfer member.

FIG. 3 is an enlarged view of the vicinity of a tandem image forming apparatus.

FIG. 4 is an enlarged view of the vicinity of an image forming unit.

FIG. 5 is a perspective view showing a collected toner conveying member of the toner recycling device.

FIG. 6 is a perspective view showing a recovered toner transport path case of the toner recycling device.

FIG. 7 is a block diagram showing an outline of an electrical equipment control system.

FIG. 8 is a flow chart of a recycled toner conveyance amount control.

FIG. 9 is a diagram showing a recycle toner supply coefficient.

FIG. 10 is a recycled toner supply amount table per unit time.

[Explanation of symbols]

10 intermediate transfer member 18 image forming means 20 tandem image forming device 22 secondary transfer device 25 fixing device 40 photoconductor 61 developing device (developing device) 63 photoconductor cleaning device (cleaning device) 65 developing sleeve 66 stirring unit 67 developing unit 68 Screw 70 Development case 71 Toner concentration sensor 76 Fur brush 77 Electric field roller 78 Scraper 79 Collecting screw 80 Toner recycling device (toner recycling means) 83 Collected toner conveying member 88 Conveying path case 100 Copier body 101 Toner scattering detection device (toner scattering amount) Detection unit) 102 Image density sensor 103 Potential sensor 104 Toner collection amount detection sensor 148 Control unit (control unit) 200 Paper feed table 300 Scanner 400 Automatic document feeder (ADF)

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H027 DA50 DD03 DE02 DE07 EA06                       EC06 EF09                 2H077 AA37 DA24 DA47 DA63 DB02                       EA03 GA03 GA13                 2H134 GA01 GB02 JA01 JA11 JA14                       KA17 KA40 KB11 KG03 KH01                       KH07

Claims (4)

[Claims] 1. An image forming apparatus comprising: a toner recycling unit that conveys the toner collected by the cleaning unit as a recycled toner to a developing unit for reuse, and a toner scattering amount detecting unit that detects a toner scattering amount from the developing unit. 2. An image forming apparatus according to claim 1, further comprising control means for controlling a carry amount of recycled toner carried from the toner recycling means to the developing means based on a detection result of the toner scattering amount detecting means. 2. The image forming apparatus according to claim 1, wherein the control unit controls the ratio of the unused toner and the recycled toner conveyed to the developing unit based on the detection result of the toner scattering amount detection unit. 3. The control unit reduces or does not convey the recycled toner to the developing unit when the toner scattering amount detected by the toner scattering amount detecting unit exceeds a predetermined amount. The image forming apparatus described. 4. The image forming apparatus according to claim 1, wherein the control unit controls the amount of recycled toner conveyed per hour to the developing unit based on the detection result of the toner scattering amount detection unit. .