JP2009192700A - Image forming apparatus - Google Patents

Abstract

An image forming apparatus that maintains stable development characteristics, transfer characteristics, and cleaning characteristics over a long period of time and does not generate abnormal images.
In a developing unit 31, a developing hopper 311 for storing toner replenished from a toner cartridge 32, a transport paddle 31d for feeding the toner in the developing hopper 311 to a toner supply member 31b, and the fed toner to a developing roller are provided. A supply roller 31b supplied to 31a, a regulation roller 31c that regulates toner on the development roller 31a to form a toner layer, and a development roller that develops the toner layer regulated by the regulation roller 31c in contact with the development roller 31a Further, a regulating roller 31c, a supply roller 31b, and a lubricant removing roller 31e are arranged in contact with the periphery of the developing roller 31a from the downstream to the upstream in the rotation direction of the developing roller 31a. A one-component developing device is used.
[Selection] Figure 3

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a fax machine, and more particularly to an image forming apparatus using an electrostatic copying process using a contact one-component developing device.

In recent years, office automation and colorization have further progressed in offices, and in addition to copying originals consisting only of conventional characters, many originals including graphs created with a personal computer are output by a printer and used as presentation materials. Opportunities to copy sheets are increasing. Many printer output images are solid images, line images, and halftone images, and accordingly, market demands required for image quality are changing, and requirements such as high reliability are further increased.
Developers used in electrophotographic systems such as electrophotography, electrostatic recording, electrostatic printing, etc., in the development process, for example, an image carrier (typically a photoconductor) on which an electrostatic latent image is formed. ) And then transferred from the photosensitive member to a transfer medium such as transfer paper in the transfer step, and then fixed on the paper surface in the fixing step. At that time, as a developer for developing the electrostatic latent image formed on the image carrier, a two-component developer composed of a carrier and a toner, and a one-component system composed of only a toner without requiring a carrier. Developers (magnetic toner, non-magnetic toner) are known. In a two-component developer, the developer deteriorates due to toner particles adhering to the carrier surface, and the toner concentration in the developer decreases because only the toner is consumed. Must be maintained at a constant rate, and therefore, there is a disadvantage that the developing device is enlarged. On the other hand, one-component developers have the advantage that the size of the apparatus can be reduced, etc., and the mainstream of the development system is because it is easy to use in any environment (low temperature, low humidity, high temperature, high humidity). It is becoming.

By the way, the one-component developer is classified into a magnetic one-component developer using a magnetic toner and a non-magnetic one-component developer using a non-magnetic toner. A magnetic one-component developing method using a magnetic one-component developer uses a developing roller provided with a magnetic field generating means such as a magnet inside to hold magnetic toner containing a magnetic material such as magnetite, and a layer thickness regulating member In recent years, many thin-layer printers have been put to practical use in small printers.
On the other hand, in the non-magnetic one-component development method using a non-magnetic one-component agent, since the toner does not have a magnetic force, a toner replenishing roller or the like is pressed against the developing roller to supply the toner onto the developing roller. Since it does not contain a colored magnetic material, it has the advantage that it can be colorized and does not use a magnet for the developing roller. In recent years, it has been put to practical use in small full-color printers and the like. However, in the one-component development system, there are still many problems to be improved.

In the two-component development system, a carrier is used as a means for charging and transporting toner, and the toner and the carrier are sufficiently stirred and mixed in the developing device and then transported to the developing roller for development. However, it is possible to maintain stable charging and conveyance, and it is easy to cope with a high-speed developing device. Compared to this, the one-component development method does not have a stable charging and conveying means like a carrier, and therefore, charging and conveyance defects are likely to occur due to long-term use and high speed.
In particular, in the non-one-component development method, after the toner is conveyed onto the developing roller, the toner is thinned by the layer thickness regulating member and developed, but the toner and the friction charging member such as the developing roller or the layer thickness regulating member are used. Since the contact / friction charging time of the toner is very short, the amount of low-charged and reverse-charged toner tends to increase more than the two-component developing method using a carrier. In addition, means for transporting the toner by at least one toner transport member and developing the electrostatic latent image formed on the image carrier by the transported toner is employed. The toner layer thickness must be as thin as possible. For this reason, in order to receive a pressing force by the layer thickness regulating member, there is a problem that the external additive added to the toner surface is embedded in the toner and the chargeability and fluidity of the toner are greatly reduced. .
Here, as an example of a conventional one-component developing device, there are known configuration examples as shown in FIGS. 10 and 11 described in Patent Documents 1 and 2.

On the other hand, in recent years, in monochrome and full-color image forming apparatuses, a mechanism for applying a lubricant such as zinc stearate to an image carrier (photosensitive member or intermediate transfer member) in order to improve the life or reduce abnormal images. Have been presented. That is, by applying fine powder of lubricant to the image carrier and forming a lubricant layer on the surface of the image carrier, toner filming of the image carrier is prevented, or a recording medium such as transfer paper from the image carrier. The life can be extended by improving the transferability to the surface, improving the cleaning property, and reducing the wear of the cleaning blade.
As a conventional example of such lubricant application, Patent Document 3 presents a method of changing the area of the lubricant in contact with the application member so that the initial lubricant application amount does not become excessive. .
Patent Document 4 proposes a method of adding a lubricant in advance to the toner in order to prevent solid white spots and filming due to lubricant application unevenness.
Patent Document 5 proposes a simple lubricant coating method in which the lubricant coating device does not become large and complicated with respect to the reduction in the toner particle size accompanying the increase in image quality.
The above example is provided with a mechanism for applying the lubricant to the image carrier for the above-described purpose, but describes a method for suppressing variation in application and side effects caused thereby.
Naturally, in order to extend the life of the image carrier and stabilize the characteristics of transfer and cleaning, it is a natural requirement that the lubricant should be applied in an appropriate amount. Has devised a lubricant application mechanism.
However, in the image forming apparatus using the above-described contact developing type single-component developing device, the developing roller, which is a toner carrier of the developing device, is in direct contact with the image carrier, particularly the photosensitive member. It has been found that the lubricant applied to the surface adheres to the surface of the developing roller via the toner on the surface of the developing roller and is taken into the developing unit side.
Patent Document 6 proposes a method for preventing toner filming by adhering and applying a lubricant to the surface of the developing roller using the incorporation of the lubricant.

JP 2002-162817 A JP 2006-208673 A JP 2002-365993 A JP 2003-263069 A JP 2004-354695 A JP 2005-250346 A

However, in the image forming apparatus based on the above-described prior art using a contact one-component developing device that has the merit of low cost and downsizing, and provided with a lubricant application device that stabilizes the life of the photosensitive member and the cleaning device, Study was carried out.
By changing the amount of lubricant applied to the photoconductor, in the one-component developing device having the configuration of Patent Document 1, the filming state of the developing roller and the lubricant adhered to the surface of the developing roller and toner. As a result of investigating the occurrence of side effects due to the incorporation into the development unit, filming was continued until the development roller filming occurred at an early stage under the condition that no lubricant was applied, and the lubricant application amount was increased to a fixed amount a. Could not be suppressed.
Furthermore, if the amount of lubricant applied is increased and the amount of lubricant applied exceeds a certain amount b (b> a), the toner conveying force of the developing roller is reduced and the amount of toner on the developing roller is reduced. The decrease in image density, the frictional charge between the toner and the developing roller, and the frictional charge between the toner and the toner layer thickness regulating member are hindered by the lubricant, resulting in background contamination, density unevenness, and transfer failure. Results were obtained.
In addition, the limit amount b of the lubricant application amount that causes these problems is the lubricant application amount c1 necessary for guaranteeing the cleaning performance, and the lubricant application necessary for reducing the cleaning wear. It was found that the amount applied was less than the amount c2. (B <c1, b <c2)
That is, as shown in FIGS. 10 and 11, in the image forming apparatus having the contact one-component developing device, when the lubricant application amount is set to the above limit amount b, the occurrence of developing roller filming can be avoided. Since the cleaning property and the life of the cleaning blade cannot be extended, and further the decrease in the amount of developer toner transported over time, an image forming apparatus with a sufficiently long life cannot be obtained.
If the application amount of the lubricant c1 or c2 is selected in order to maintain the cleaning property, a decrease in the developer toner conveyance amount occurs at an early stage, causing a problem that an unclear image (blurred image) is generated. It becomes easy.
Here, it has been found that the amount of the lubricant taken into the surface of the developing roller becomes smaller as the amount of the developing toner increases, that is, when the toner moves more from the developing roller to the photosensitive member during the developing operation. .

Therefore, the higher the frequency of taking an image with a high image area ratio, the lower the amount of lubricant taken in, but the user does not necessarily output only a large area image. In order to reduce this, after a large number of low-area images are output, a method of consuming toner at the time of non-image formation for a shortage with respect to a certain area ratio may be used.
For example, if images with an area ratio of 6% or more are always taken, the amount of lubricant taken in can be suppressed, and the lower limit of toner consumption that can prevent the occurrence of unclear images (blurred images) is less than that. When an image with an area of approximately 3% consisting mainly of text, which is an area, continues to be output, the toner of 3% of the difference is consumed from the developing roller to the photoreceptor during non-image formation, and the lubricant is taken in. The amount can be suppressed.
However, this method wastes toner that can be originally used for printing, which causes a mutual disadvantage for both the user who uses the apparatus and the manufacturer who provides the apparatus.

  Accordingly, the present invention has been made in view of the above-described problems, and its object is to provide an image forming apparatus that maintains stable development characteristics, transfer characteristics, and cleaning characteristics over a long period of time and does not generate abnormal images. It is.

The features of the present invention, which is a means for solving the above problems, are listed below.
An image forming apparatus of the present invention includes an image carrier that forms a latent image, a charging device that uniformly charges the surface of the image carrier, an exposure device that exposes the charged image carrier surface to form a latent image, and an image A contact one-component developing device for bringing a toner carrier into contact with the carrier and supplying toner to the latent image formed on the image carrier for development; and a toner image on the image carrier directly transferred to a recording medium or intermediate A transfer device for transferring to a recording medium after transfer to a transfer body, a cleaning device for removing toner remaining on the image carrier or intermediate transfer body, and a fixing device for fixing a toner image on the recording medium; In the image forming apparatus having means for applying a lubricant to the image carrier, the contact one-component developing device is configured by arranging a toner cartridge for supplying toner to the developing unit, and the developing unit includes a toner cartridge. A developing hopper that stores toner replenished from the ridge, a transport paddle that sends toner in the developing hopper to the toner supply member, a toner supply member that supplies the supplied toner to the toner carrier, and a toner on the toner carrier. A toner layer regulating member that forms a toner layer by regulation, and a toner carrier that develops the toner layer regulated by the toner layer thickness regulating member in contact with the image carrier, and further comprising the toner carrier A toner layer thickness regulating member, a toner supply member, and a lubricant removing member are disposed in contact with the periphery of the body from the downstream side to the upstream side in the rotation direction of the toner carrier.
In the image forming apparatus of the present invention, the contact one-component developing device further includes a communication port through which the toner passes between the toner cartridge and the developing unit, and a developing hopper side for controlling the amount of toner to pass therethrough. A control valve is provided on the inner surface.
The image forming apparatus of the present invention is further characterized in that the lubricant removing member is constituted by a sponge roller, and the diameter of the foam cell on the surface thereof is in the range of 0.1 mm to 2 mm.
The image forming apparatus of the present invention is further characterized in that the toner in the developing hopper is supplied to the surface of the lubricant removing member.
The image forming apparatus according to the present invention further includes a lubricant removal contact member that contacts the surface of the lubricant removal member.
Further, the image forming apparatus of the present invention is further characterized in that the toner in the developing hopper is supplied to the surface of the lubricant removing member and a contact portion of the lubricant removing contact member.
Further, in the image forming apparatus of the present invention, the rotation direction of the lubricant removing member is opposite to the rotation direction of the toner carrier (counter direction) at the contact portion. The lubricant removing member is rotated, and the peripheral speed of the lubricant removing member is set to a peripheral speed ratio of 0.5 to 2 times the peripheral speed of the toner carrier.
Further, in the image forming apparatus of the present invention, the rotation direction of the toner supply member is reverse (counter direction) at the contact portion with respect to the rotation direction of the toner carrier, and The lubricant removing member is rotated so that the rotation direction of the lubricant removing member is the same direction (coordinate direction) at the contact portion with respect to the rotation direction of the toner carrier, and further the lubricant The peripheral speed of the removing member is a peripheral speed ratio of 1.1 to 3 times the peripheral speed of the toner carrier.
Further, the image forming apparatus of the present invention further applies a voltage between the toner carrier and the lubricant removing member in order to form an electric field in which the toner moves from the toner carrier to the lubricant removing member. A voltage applying means for applying is provided.
The image forming apparatus of the present invention is further characterized in that the additive amount of the toner external additive used in the developing device is between 1.2 parts by weight and 7 parts by weight with respect to the toner. To do.
The image forming apparatus of the present invention is further characterized in that a toner stirring member is provided below the lubricant removing member.

The present invention, which is a means for solving the above problems, has the following specific effects.
The image forming apparatus of the present invention uses a contact one-component developing device having the advantages of low cost and downsizing, and is provided with a lubricant coating device that stabilizes a photoconductor and a cleaning device with a long life and stabilizes an image. By suppressing the influence on the toner layer on the developing roller due to the incorporation of the lubricant into the developing device, the adhesion amount of the toner layer can be stabilized over a long period of time, and the cost can be reduced and the service life can be extended.
Further, the image forming apparatus of the present invention further suppresses toner deterioration and deterioration of the characteristics of the developing roller by improving the circulation of the toner in the developing apparatus, and the developing roller by incorporating the lubricant into the developing apparatus. The influence on the upper toner layer can be suppressed, and the adhesion amount of the toner layer can be stabilized over a long period of time, resulting in a low cost and a long life.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus according to an embodiment of the present invention.
The image forming apparatus 1 includes a photosensitive unit 10, a writing optical unit 20, a developing unit 30, an intermediate transfer unit 40, a secondary transfer unit 50, a fixing unit 60, a duplex printing paper reversing unit 70, and the like. Then, black (hereinafter referred to as Bk), cyan (hereinafter referred to as C), magenta (hereinafter referred to as M), and yellow (hereinafter referred to as Y) color images are successively developed on the photoreceptor belt 11 of the photoreceptor unit 10. These are then superimposed to form the final four-color full-color image. Around the photoreceptor belt 11, a photoreceptor cleaning device 12, a charging roller 13, a plurality of developing devices 30, an intermediate transfer belt 41 of an intermediate transfer unit 40, and the like are disposed. The photosensitive belt 11 is stretched between a driving roller 14, a primary transfer counter roller 15, and a stretching roller 16, and is rotated by a driving motor. The writing optical unit 20 converts color image data into an optical signal, performs optical writing corresponding to each color image, and forms an electrostatic latent image on the photosensitive belt 11. The writing optical unit 20 includes a semiconductor laser 21 as a light source, a polygon mirror 22, three reflecting mirrors 23, and the like.

The developing device 30 includes, in order from the bottom of the image forming apparatus 1 main body, a Bk developing device 30K containing black toner, a C developing device 30C containing cyan toner, an M developing device 30M containing magenta toner, and a yellow. A Y developing device 30Y containing toner is provided. Here, a contact / separation mechanism (not shown) is further provided that moves each developing device 30 in the left-right direction in the drawing to perform contact / separation operation with respect to the photosensitive belt 11.
The toner in the developing device 30 is charged with a predetermined polarity. A developing bias is applied to the developing roller 31a by a developing bias power source, and the developing roller 31a is biased to a predetermined potential with respect to the photosensitive belt 11. The contact / separation mechanism moves the developing device 30 toward the photosensitive belt 11 by the driving force when an electromagnetic clutch (not shown) for transmitting driving from the motor to each developing device 30 is turned on. At the time of development, any one selected from the developing device 30 moves and contacts the photosensitive belt 11. On the other hand, when the electromagnetic clutch is turned off and the drive transmission is released, the developing device that has been in contact with the photosensitive belt 11 moves away from the photosensitive belt 11.
In the standby state of the main body of the image forming apparatus 1, the developing devices 30K, C, M, and Y are also set at positions separated from the photosensitive belt 11, and when the image forming operation is started, the laser beam is based on the color image data. Is started, and electrostatic latent image formation is started (hereinafter, an electrostatic latent image based on Bk image data is referred to as a Bk electrostatic latent image; the same applies to C, M, and Y). Before the leading edge of the electrostatic latent image reaches the Bk development position so that the leading edge of the Bk electrostatic latent image can be developed, the Bk developing roller 31a starts to rotate, and the Bk electrostatic latent image is transformed with Bk toner. develop. Thereafter, the developing operation of the Bk electrostatic latent image area is continued, but when the rear end portion of the Bk electrostatic latent image passes the Bk developing position, the K developing device 30K is separated from the photosensitive belt 11, The corresponding color developing device 30 contacts the photosensitive belt 11 in preparation for the next color development. This is completed at least before the leading edge of the electrostatic latent image based on the next image data reaches the developing position.

The intermediate transfer unit 40 includes an intermediate transfer belt 41, a belt cleaning device 42, a position detection sensor 43, and the like. The intermediate transfer belt 41 is stretched around a drive roller 44, a primary transfer roller 45, a secondary transfer counter roller 46, a cleaning counter roller 47, and a tension roller 48, and is driven and controlled by a drive motor (not shown). A plurality of position detection marks are provided in the non-image forming area at the end of the intermediate transfer belt 41, and any one of these position detection marks is detected by the position detection sensor 43, and this detection is performed. Image formation starts at the timing. Further, the belt cleaning device 42 includes a cleaning brush 42a, a contact / separation mechanism, and the like, while transferring the Bk image of the first color to the intermediate transfer belt 41 and the images of the second, third, and fourth colors. During the transfer to the intermediate transfer belt 41, the cleaning brush 42a is separated from the surface of the intermediate transfer belt 41 by the contact / separation mechanism.
Further, the secondary transfer unit 50 includes a contact / separation mechanism including a clutch or the like for contacting / separating the secondary transfer roller 51, the secondary transfer roller 51 with the intermediate transfer belt 41. The secondary transfer roller 51 swings about the rotation axis of the contact / separation mechanism in accordance with the timing when the transfer paper reaches the transfer position. The secondary transfer roller 51 and the secondary transfer counter roller 46 bring the transfer paper and the intermediate transfer belt 41 into contact with each other with a constant pressure. The secondary transfer roller 51 maintains the positional accuracy of the parallelism with the secondary transfer counter roller 46 by a positioning member (not shown) provided in the intermediate transfer unit 40. Further, the contact pressure of the secondary transfer roller 51 with respect to the intermediate transfer belt 41 is made constant by a positioning roller (not shown) provided on the secondary transfer roller 51. At the same time as the secondary transfer roller 51 is brought into contact with the intermediate transfer belt 41, a transfer bias having a polarity opposite to that of the toner is applied to the secondary transfer roller 51, and the superimposed toner images on the intermediate transfer belt 41 are collectively transferred onto the transfer paper.

On the other hand, at the time when the image forming operation is started, the transfer paper is fed from either the transfer paper cassette 80 or the manual feed tray 83 and is waiting at the nip of the pair of registration rollers 82. Then, when the leading edge of the four-color superimposed toner image on the intermediate transfer belt 41 approaches the secondary transfer roller 51, the registration roller pair 82 is driven so that the leading edge of the transfer paper coincides with the leading edge of the toner image. The transfer paper and the toner image are aligned. Then, the transfer paper is superimposed on the toner image on the intermediate transfer belt 41 and passes through the secondary transfer position. At this time, the transfer paper is charged by the transfer bias by the secondary transfer roller 51, and most of the toner image is transferred onto the transfer paper. Then, the transfer paper onto which the four-color superimposed toner images are collectively transferred from the intermediate transfer belt 41 is conveyed to the fixing unit 60, and the toner image is melted at the nip portion between the fixing belt 61 and the pressure roller 62 controlled to a predetermined temperature. It is fixed, sent out of the apparatus main body, and stacked face down on the paper discharge tray 84 to obtain a full color copy.
Furthermore, when performing duplex printing, the transfer paper that has passed through the fixing unit 60 is sent to the duplex printing paper reversing unit 70 by the duplex switching claw 85. In the double-sided printing paper reversing unit 70, the transfer paper is first guided in the direction of arrow D by the reversal switching claw 71, and after the rear end of the transfer paper passes through the reversal switching claw 71, the reversing roller pair 72 stops and the transfer paper also Stop. Then, the reverse roller pair 72 starts reverse rotation after a certain blank time, and the transfer paper starts to switch back. At this time, the reverse switching claw 71 is switched, and the transfer paper is sent to the registration roller pair 82. The transfer sheet sent to the registration roller pair 82 stands by at the nip of the registration roller pair 82 with the front and back reversed. Then, the registration roller pair 82 is driven at a predetermined timing, the transfer paper is sent to the secondary transfer position, and the four-color superimposed toner image is collectively transferred from the intermediate transfer belt 41, and then the toner image is melted by the fixing unit 60. It is fixed and sent out of the main body.
On the other hand, the surface of the photoconductor belt 11 after the primary transfer can be cleaned by the photoconductor cleaning device 12 and uniformly discharged with a charge removal lamp or the like to facilitate cleaning. Further, the surface of the intermediate transfer belt 41 after the toner image is transferred onto the transfer paper is cleaned by pressing the cleaning brush 42a of the belt cleaning device 42 with a contact / separation mechanism. The toner cleaned from the intermediate transfer belt 41 is stored in a waste toner tank 49.

Here, a lubricant application device for the photoconductor is provided in the photoconductor cleaning device 12. FIG. 2 is a schematic view showing the configuration of the lubricant application device in detail.
As shown in FIG. 2, a lubricant bar 12c obtained by molding a lubricant powder into a rod shape and rotating while contacting the lubricant bar 12c, scraping and conveying the lubricant particles from the lubricant bar 12c to the photoreceptor. A lubricant application brush 12b for applying the lubricant particles and a lubricant pressurizing means 12d for bringing the lubricant bar 12c into contact with the lubricant application brush 12b with a predetermined pressure are provided. In FIG. 2, the flat plate member at the upper part of the lubricant bar 12c is a weight 12d, and the lubricant bar 12c is pressed against the lubricant application brush 12b.
Further, the lubricant particles applied to the surface of the photoreceptor are spread evenly on the surface of the photoreceptor by the cleaning blade 12a of the photoreceptor cleaning device 12 to form a lubricant layer on the surface of the photoreceptor.
Lubricants include zinc stearate, barium stearate, calcium stearate, iron stearate, copper stearate, magnesium stearate, zinc oleate, manganese oleate, copper oleate, palmitic acid, calcium palmitate, magnesium palmitate Metal fatty acids such as aluminum palmitate can be used.
Furthermore, the lubricant application brush 12b is yarn is a carbon dispersion acrylic fiber, 6 to 15 denier thickness, density is 30k~100k present / inch ^2. The rotation of the lubricant application brush is controlled by changing the application time and the rotation speed according to the required application amount of lubricant according to the area ratio of the output image, the number of continuous images, the environmental conditions of temperature and humidity, etc. The method is taken.

FIG. 3 is a schematic diagram showing the configuration of the developing device provided in the image forming apparatus according to the embodiment of the present invention.
The developing device 30 includes a developing unit 31 that develops the latent image of the photoconductor 11 as an image carrier with toner as a developer, and a toner cartridge 32 that replenishes the developing unit 31 with toner.
The developing unit 31 faces the photoconductor 11 and supplies toner onto the developing roller 31a, which is a toner carrier that conveys toner to a developing area formed between the photoconductor 11 and the developing roller 31a. A supply roller 31b, a regulating roller 31c that is a layer thickness regulating member that regulates the amount of toner on the developing roller 31a, and a first conveyance paddle 31d that conveys toner are provided.
The toner cartridge 32 includes first and second storage chambers 321 and 322 that store toner, and second and third transport paddles 32 a and 32 b that transport the toner to the developing unit 31.

With regard to the developing operation, the first transport paddle 31d in the developing unit 31 transports the toner to the developer supply roller 31b while stirring, and the supply roller 31b rubs against the development roller 31a while simultaneously rubbing the toner. The toner is charged by friction charging. The charged toner is attracted to the developing roller 31a with a mirror image force and conveyed. Thereafter, a toner thin layer formed on the developing roller 31a is formed by regulating the amount of toner conveyed to the developing region by the regulating roller 31c. In the developing area, a developing bias is applied to the developing roller 31a to form a developing electric field, and the electrostatic image on the photosensitive belt 11 is developed.
As described in the section of problems in the prior art, the developing roller 31a and the photosensitive member 11 are in contact with each other via a toner layer on the developing roller during the developing operation, and the lubricant layer on the surface of the photosensitive member is the developing roller 31a or A part or most of the surface is peeled off from the surface of the photosensitive member under the mechanical force from the toner layer.
The separated fine particles of the lubricant adhere to the surface of the toner or the additive that externally adds the surface of the toner.
If the toner to which the lubricant is attached moves from the developing roller surface to the photoreceptor side by the developing operation, the lubricant is returned to the photoreceptor again. However, the toner containing the lubricant is conveyed on the developing roller for a portion where there is no image that is not developed.
When the toner having the lubricant adhered to the surface is subsequently rolled or moved on the developing roller, the lubricant adheres to the developing roller surface from the toner.

In addition, toner containing the lubricant is likely to accumulate at the toner staying portion (particularly at the nip entrance of the toner regulating member 31c), and the concentration of the lubricant locally tends to be higher than other locations. .
Each time the developing roller 31a passes through the staying portion, the adhesion of the lubricant advances on the surface of the developing roller 31a, and the lubricant coverage on the developing roller increases. As a result, the frictional charging action between the developing roller surface and the toner is hindered by the lubricant covering the developing roller surface, the toner charge amount is reduced, or the lubricant reduces the friction coefficient of the developing roller surface, The ability to physically adhere and transport toner can be reduced, making it impossible to form an appropriate toner layer on the developing roller, resulting in poor toner supply, reduced density, blurred images, and worsening of background stains. Cause problems.
This problem is mainly caused by taking the lubricant of the photoconductor 11 into the developing roller 31 through the toner, but in the configuration of the developing device 30 in which toner containing a large amount of lubricant stays in the vicinity of the developing roller. There are also factors that cause development fading in a shorter time.
That is, long before the developing device 30 reaches the end of its life, and even though a large amount of unused toner remains in the toner cartridge 32, it causes an abnormal density drop and is used to the original end due to wear of the developing roller. Even if a sufficient amount of toner remains in the toner cartridge 32, the decrease in density is not restored and the developing device 30 has to be replaced, resulting in a large loss.

In this embodiment, in order to prevent such a situation and to enable the developing device 30 to be used up to its original life, in this embodiment, the toner containing the lubricant is applied to the developing nip in the photosensitive member 11 by the developing roller 31a. Even if the toner is transported after passing, the toner is removed by the lubricant removing roller 31e, whereby the ratio of the toner containing the lubricant on the developing roller after passing the lubricant removing roller 31e is reduced, and the supply roller 31b or At the contact portion between the toner layer thickness regulating member 31c and the developing roller 31a, the opportunity for the lubricant to adhere to the surface of the developing roller is reduced, and the increase in the amount of lubricant adhering on the developing roller is suppressed.
Here, the toner containing the lubricant is moved from the periphery of the developing roller into the hopper, and agitated and contacted with the toner to which the lubricant on the hopper is not adhered, so that the lubricant adhering to the toner particles is moved to another hopper. The amount of lubricant adhering to each toner is averaged by diffusing to the toner, the ratio of the toner to which much lubricant is adhering is reduced, and even if it adheres again to the developing roller 31a, Limiting the amount of lubricant to come out.

Next, the action of removing the lubricant will be further described.
In FIG. 3, the lubricant removing member 31e is used as a foaming roller. However, as an embodiment other than the foaming roller, the lubricant removing member 31e is used for the purpose of removing the toner containing the lubricant from the developing roller 31a. 31e can be a plate-like member such as a scraper. For example, a resin blade such as a metal blade polyethylene or polyethylene terephthalate having a thickness of about 0.05 mm to 0.2 mm made of a stainless steel plate or phosphor bronze plate, a polyurethane rubber blade, or the like.
Further, even with a roller-like lubricant removing member 31e having a smooth surface that is not foamed, the toner is moved from the developing roller 31a to the developing roller 31a side by the action of an electric field or the like to be removed from the developing roller surface to some extent. Can be reached. For example, a semi-conductive EPDM, a rubber roller such as polyurethane or silicon, and a two- or more-layered elastic roller in which smoothness is improved by coating a resin on a rubber roller.
However, in order to prevent the developing roller 31a from being damaged or worn, the contact pressure between the lubricant removing member 31e and the developing roller 31a is reduced as much as possible, and the toner containing the lubricant on the lubricant removing member 31e is used. It is more desirable to select the foaming roller 31e as the removing member because it is easy to peel off the surface from the surface.

Accordingly, the following description will be made on the lubricant removing member 31e of the foam roller.
The lubricant removing roller 31e is disposed on the upstream side of the toner supply roller 31b with respect to the rotation direction of the developing roller 31a. The lubricant removing roller 31e is in contact with the developing roller 31a by forming a predetermined nip. It can be rotated by the drive system. In the case of contact one-component development, the toner thin layer formed by the layer thickness regulating member 31c is often formed of two or more layers on the surface of the developing roller instead of a single layer. That is, the toner on which the lubricant is likely to move and adhere from the surface of the photoreceptor is the toner located in the uppermost layer of the toner layer on the developing roller. Since the contact force of the illustrated inlet seal 31h (the film member disposed further upstream of the removal roller 31e) is not so strong, the lubricant contained in the toner is applied to the developing roller 31a here. It is considered that the toner containing the lubricant is conveyed to the lubricant removing roller 31e while passing through the nip with the photoconductor 11.
The lubricant removing roller 31a can reduce the amount of toner containing the lubricant on the developing roller to some extent by removing the uppermost layer toner containing a relatively large amount of lubricant. By sufficiently securing the contact of the removing roller 31a with the developing roller 31a and removing most of the toner conveyed to the developing roller 31a, the amount of toner including a lubricant is further reduced.
Further, the contact pressure between the lubricant removing roller 31e and the developing roller 31a is increased, and the lubricant adhering to the surface of the developing roller 31a is peeled off and the surface of the developing roller 31a is cleaned, so that the proper toner is always obtained Allow layers to be formed.
Therefore, with these, using a contact one-component developing device with the merit of low cost and downsizing,
While providing a lubricant application device that stabilizes the photoconductor and cleaning device for a long service life,
By suppressing the influence on the toner layer on the developing roller 31a due to the incorporation of the lubricant into the developing device, the adhesion amount of the toner layer is stabilized over a long period of time,
A low-cost and long-life image forming apparatus can be obtained.

Next, the toner between the developing hopper 31 and the cartridge 32 according to claim 2 is circulated, and the toner to which the lubricant removed from the developing roller 31a by the lubricant removing roller 31e adheres to the other toner. An embodiment that can increase the probability and stabilize the toner at an early stage will be described.
FIG. 4 is a schematic diagram illustrating a configuration of a developing device provided in the image forming apparatus according to the embodiment of the present invention. This type is equipped with a control valve to improve toner circulation in the cartridge and developing hopper. In this circulation type, since the toner is circulated and stirred between the cartridge 32 and the developing hopper 311, the degree of deterioration is made uniform, and the toner characteristics can be suppressed with minimal toner deterioration without excessive deterioration. This is better for stability.
The developing device 30 includes a developing unit 31 that develops the latent image of the photoconductor 11 as an image carrier with toner as a developer, and a toner cartridge 32 that replenishes the developing unit 31 with toner.
The developing unit 31 faces the photoconductor 11 and supplies a toner onto the developing roller 31a, which is a developer carrying member that conveys the toner to a developing area formed between the developing unit 31 and the developing roller 31a. Supply roller 31b, a regulating roller 31c that is a layer thickness regulating member that regulates the amount of toner on the developing roller 31a, and a first conveyance paddle 31d that conveys toner.
The toner cartridge 32 includes first and second storage chambers 321 and 322 that store toner, second and third transport paddles 32a and 32b that transport the toner to the developing unit 31, and a second transport paddle 32a. A protruding rib 35 is provided at the bottom of the toner cartridge 32 where the toner cartridge rotates.

Here, a non-magnetic one-component developer is used as the developer. However, in the non-magnetic one-component developer, the external additive on the toner surface has a great influence on the chargeability and fluidity of the toner. In a magnetic one-component developer, developability can be controlled by the strength of magnetization depending on the amount of magnetic material. In the non-magnetic one-component developer, the developability is greatly influenced by the charge amount and fluidity due to the external additive. Therefore, when used in the developing device 30 of the present invention, a stable toner surface state can be obtained.
In the developing device 30, the developing unit 31 and the toner cartridge 32 are arranged in parallel in the horizontal direction. Further, the toner cartridge 32 and the developing unit 31 are provided with a communication port 33 through which the toner passes between the toner cartridge 32 and the developing unit 31. Further, a control valve 34 is provided at the communication port 33 on the developing unit 31 side.
The developing device 30 of the present invention allows the toner to pass through the communication port 33. As a result, the toner consumed in the developing unit 31 is supplied from the toner cartridge 32 to the developing unit 31, and the toner deteriorated in the developing unit 31 is transferred from the developing unit 31 to the toner cartridge 32 through the communication port 33. Discharge. The toner cartridge 32 can be replaced independently of the developing unit 31 independently.

The toner is subjected to a pressing force by the toner supply roller 31b and the regulating roller 31c in the developing unit 31. By receiving this pressing force, the toner surface is not smooth, the surface becomes smooth, the adhesion to the photoconductor 11 is increased, and cleaning becomes difficult. Therefore, when the environment becomes low humidity, cleaning failure may occur. In addition, although transferability is improved, fogging appears on a white background portion that has not been visually observed even if it has been transferred conventionally. Further, when the toner is pressed, the external additive present on the toner surface is buried inside the toner. This will be described in detail later with regard to the external additive, but the external additive is harder than the toner, and is therefore buried in the toner. As the external additive present on the toner surface decreases, the chargeability of the toner changes. In particular, since silica used as an external additive has a large specific surface area, the charge amount is high, and the charge amount of the toner varies greatly depending on the amount of the external additive on the toner surface due to burying. Another effect is that the fluidity of the toner is reduced by burying the external additive. This fluidity indicates the adhesion force of the toner. If the fluidity is high, the adhesion force between the toner and, for example, the photoreceptor 11 is reduced. Similarly, the adhesion between the developing roller 31a and the toner is reduced to improve the developability. On the contrary, when the amount of the external additive existing on the toner surface is reduced due to the embedding, that is, the fluidity of the toner is lowered and the developability is lowered.
Therefore, in the developing device 30 of the present invention, the toner in the developing unit 31 is temporarily removed from the toner cartridge 32 through the communication port 33 for supplying the deteriorated toner in the developing hopper 311 from the toner cartridge 32 to the developing unit 31. The toner cartridge 32 is mixed with undeteriorated toner in the toner cartridge 32, and the additive is transferred to the deteriorated toner to be recovered, and at the same time, the ratio of the deteriorated toner amount is reduced. The developing unit 31 is supplied again through the communication port 33 and replenished to stabilize the charging of the toner in the developing hopper 311.

In the image forming apparatus 1 of the present invention, the lubricant adhering to the toner surface is transferred to another toner, so that the adhering amount of the lubricant is averaged over the entire toner, so that the toner around the developing roller 31a becomes the lubricant. In order to prevent the adhesion amount from becoming high, a toner agitating member 31g is provided below the lubricant removing member (lubricant removing roller) 31e and the lubricant removing contact member (contact member) 31f.
FIG. 5 is a schematic diagram showing a configuration of a developing device provided in the image forming apparatus according to the embodiment of the present invention.
The toner containing the lubricant removed from the developing roller 31a by the lubricant removing roller 31e is conveyed to the lubricant removing roller 31e and developed from the surface of the lubricant removing roller 31e by the removing contact member 31f as described above. It is scraped off by the hopper 311.
If the toner containing the lubricant is only present in the developing hopper 311, the lubricant cannot be transferred efficiently. The toner of the developing hopper 311 receives a moving force due to the mixing / stirring by the rotation of the first transport paddle 31d, so that the toner moves.
Further, the toner in the developing hopper 311 and the toner in the cartridge 32 are moved back and forth through the communication port 33 between the developing hopper 311 and the toner cartridge 32, and the toner is circulated throughout the developing device 30 so that the toners come into contact with each other. Thus, the toner lacking the additive is subjected to the transfer of the additive, and the toner having a large amount of lubricant attached is transferred to the toner having a small amount of the lubricant.
However, in order to more efficiently realize the transfer of the lubricant, it is preferable to stir the toner in the developing hopper 311 in the vicinity of the removing roller 31e and before being transported to the supply roller 31b by the first transport paddle 31d. Is effective.
Accordingly, here, the toner agitating member 31g is arranged below the lubricant removing roller 31e, and the toner and lubricant in the developing hopper 311 which are fed by the transport paddle 31d and diffused and averaged are increased. By agitating the contained toner on the spot, the uneven adhesion of the lubricant is quickly leveled.

The toner stirring member 31g is considered to be better to rotate counterclockwise in FIG. 5 for the following reason. That is, since the toner containing the lubricant is subjected to a moving force in a direction away from the supply roller 31b by the stirring member 31g, the time for re-arrival to the developing roller 31a can be lengthened, and the toner of the developing hopper 311 The number of times of contact increases, and the lubricant can be transferred efficiently.
The flow of the toner sent by the first transport paddle 31d and the flow of the toner by the stirring member 31g collide with each other, and the mixing and stirring property of the toner containing the lubricant and the toner sent by the transport paddle 31d is improved. In addition, more contact between toners can be caused.
The rotation of the stirring member 31g improves the flow of toner, improves the flow of toner around the developing roller 31a, particularly in the vicinity of the supply roller and the toner regulating roller, and prevents the staying of deteriorated toner.
The shape of the stirring member 31g may be one in which blades are provided radially around the shaft, and although not shown in order to generate a moving force in the axial direction, the vicinity of the center of the shaft may be screw-shaped. good.
In addition, providing flicker (not shown) that contacts the blades of the stirring member 31g also improves the stirring effect and can quickly average the toner adhesion amount of the toner.
As a result, the mixing and stirring property of the toner containing the lubricant and the toner of the developing hopper 311 fed by the transport paddle 31d is improved, and more contact between the toners can be caused. Further, the rotation of the agitating member 31g improves the toner flow, improves the toner flow around the developing roller 31a, particularly in the vicinity of the supply roller 31b and the toner regulating roller 31c, and prevents retention of deteriorated toner. Each of the above actions suppresses the influence on the toner layer on the developing roller 31a due to the incorporation of the lubricant into the developing device 30 and stabilizes the amount of toner layer deposited over a long period of time, thereby reducing the cost and length. The lifetime of the image forming apparatus 1 can be obtained.

FIG. 6 is a schematic view showing the structure of a control valve arranged in the developing unit in the developing device of the present invention. FIG. 7 is a schematic view showing the shape of the communication port.
As shown in FIG. 6, the control valve 34 is provided corresponding to the communication port 33 of the developing unit 31, and the control valve 34 is attached to the support portion 34 a and is disposed in the housing. As shown in FIG. 6, the control valve 34 has a rectangular shape corresponding to each communication port 33, and the portions without the communication port 33 are alternately provided without the control valve 34. The support portion 34a is made of a metal having rigidity and uses SUS, Cu, or Al. The control valve 34 is an elastic resin film 34b and uses polypropylene, polyethylene, polyester resin, or fluororesin.
The first transport paddle 31d of the developing unit 31 includes a paddle film. This film may be a single film or a plurality of films. The first transport paddle 31d rotates and supplies the toner supplied from the toner cartridge 32 side to the developing roller 31a. The film may be plate-shaped. Further, with respect to the comb-like rectangular control valve 34 provided corresponding to the communication port 33, only the portion corresponding to the control valve 34 may be rectangular. Moreover, when providing two or more sheets, you may use combining these.

FIG. 8 is a schematic diagram for explaining a state in which toner is supplied from the toner cartridge side to the developing unit. As shown in FIG. 8A, the first transport paddle 31d provided in the developing unit 31 is rotating, and the control valve 34 opens the communication port 33 by the elastic deformability of the control valve 34 itself. It is energized in the direction to do. As shown in FIG. 8 (2), the first transport paddle 31 d rotates in the direction of the arrow in the figure, hits the control valve 34, and the control valve 34 is pressed in the direction of the arrow in the figure to thereby connect the communication port 33. It is transformed so as to block.
Next, in FIG. 8 (3), after that, the first transport paddle 31d passes, the elastic control valve 34 is quickly bounced back, and at the same time, the communication port 33 is opened. When the communication port 33 is opened, as shown in FIG. 8 (4), the toner pushed by the toner cartridge 32 is replaced by the toner pushed from the toner cartridge 32 side through the communication port 33. 31 side is supplied.

FIG. 9 is a schematic diagram for explaining a state where toner on the toner cartridge side is supplied. As shown in FIG. 9, the toner cartridge 32 is transported to the first storage chamber 321 by the third transport paddle 32b of the second storage chamber 322, and further transported to the developing unit 31 side by the second transport paddle 32a. To do.
Specifically, as shown in FIG. 9A, the second transport paddle 32a includes a single paddle film, and the toner is pressed against the toner in the toner cartridge 32 by rotating the film. However, it rotates in the direction of the arrow in the figure. At this time, as shown in FIG. 9B, the second transport paddle 32a transports the toner to the developing unit 31 side. Further, by providing the rib 35 in the first storage chamber 321, as shown in the figure, when the previous paddle film hits the rib 35, the toner is blocked by the rib 35, and the rib 35 and the second A space without toner is formed between the transport paddle 32a and the transport film. This space is gradually filled by the intrusion of toner with good fluidity, but a space is formed inside the toner for a certain period of time. Further, when the transport film of the second transport paddle 32a rotates, the toner also enters the space from above, so there is no space inside the toner. Next, when rotating in this state, the transport film of the second transport paddle 32a is in a state where the toner is pushed into the developing unit 31, and the control valve 34 of the developing unit 31 is moved to the first transport paddle. The toner is moved from the toner cartridge 32 side to the developing unit 31 side through the communication port 33 by being overlapped with the time when the control valve 34 is opened without being pressed by the 31d paddle film.
Next, as shown in FIG. 9 (3), the toner in the developing unit 31 enters through the open communication port 33. This is because the paddle film of the first conveyance paddle 31d rotates and the toner that pushes the control valve 34 is pushed from the developing unit 31 side to the toner cartridge 32 side and the paddle of the second conveyance paddle in the first storage chamber 321. The toner film creates a space inside the toner, and when the space just reaches the communication port 33, the toner moves through the communication port 33 from the developing unit 31 side to the toner cartridge 32 side and is discharged.

The movement of the first, second and third transport paddles 31d, 32a and 32b between the developing unit 31 and the toner cartridge 32 and the toner movement in the developing device 30 at this time will be described in more detail.
10A to 10C are schematic diagrams for explaining the state of toner movement between the developing unit and the toner cartridge. Here, the developing roller 31a and the like in the developing unit 31 are omitted.
In the developing device 30, as shown in FIG. 10 (1), the control valve 34 in the developing unit 31 is adhered to the support and has a certain angle. The first transport paddle 31d rotates a plurality of paddle films. The second and third transport paddles 32a and 32b in the toner cartridge 32 rotate a single paddle film. As shown in FIG. 10 (2), in the developing unit 31, a plurality of paddle films push the control valve 34 in the first transport paddle 31 d, and at this time, the first transport paddle 31 d is between the control valve 34 and the communication port 33. Since the toner cartridge 32 side is also filled with toner, the toner cannot move through the communication port 33 and returns from the control valve 34 in the developing unit 31 into the developing unit 31 in the lateral direction. Next, as shown in FIG. 10 (3), in the first transport paddle 31 d, the plurality of paddle films push the control valve 34 further, and there is almost no gap between the control valve 34 and the communication port 33. Become. Next, as shown in FIGS. 10 (4) and 10 (5), the first transport paddle 31d has the control valve 34 returned to the original angle as the plurality of paddle films are separated from the control valve 34. Sometimes, a large gap is formed, and the toner is moved and supplied from the toner cartridge 32 side through the communication port 33 by forming a space.
Furthermore, as shown in FIG. 10 (6), the paddle film of the first transport paddle 31d pushes the control valve 34 again by having a plurality of sheets. At this time, the paddle film of the second transport paddle 32 a hits the rib 35 in the second storage chamber 322 in the toner cartridge 32. When further rotated, as shown in FIG. 10 (7), the paddle film of the first transport paddle 31 d further pushes the control valve 34, and a state without a gap is formed between the control valve 34 and the communication port 33. At this time, when the paddle film of the second transport paddle 32a is rotated first from the rib 35, the rib 35 becomes an obstacle and the toner is not transported, so that a space is formed inside the toner. Further, as shown in FIGS. 10 (8) and 10 (9), the first transport paddle 31d is moved back to the original angle by the plurality of paddle films being separated from the control valve 34. In addition, by forming a space with a large gap, the toner lifted by the paddle film of the second transport paddle 32a is further moved and supplied from the toner cartridge 32 side through the communication port 33.

However, next, as shown in FIG. 10 (10), the paddle film of the first transport paddle 31d pushes the control valve 34 again by having a plurality of sheets. Until now, there has been toner in the vicinity of the communication port 33 on the toner cartridge 32 side. Instead of returning to the inside, it is moved from the developing unit 31 side to the toner cartridge 32 side through the communication port 33 and discharged. As shown in FIGS. 10 (11) and 10 (12), the paddle film of the first transport paddle 31d pushes the control valve 34 again to further move from the developing unit 31 side to the toner cartridge 32 side. It is moved and discharged.
Further, by making the rotation speed of the first transport paddle 31d faster than that of the second transport paddle 32a, as shown in FIGS. 10 (13) to 10 (16), the first transport paddle 31d moves from the developing unit 31 side to the toner cartridge 32 side. Can be discharged.
By repeating this, the toner can be moved through the communication port 33 between the developing unit 31 and the toner cartridge 32.

Here, by controlling the rotational speeds of the first transport paddle 31d in the developing unit 31 and the second transport paddle 32a in the toner cartridge 32, the amount of supply / discharge due to the movement of the toner can be adjusted. In particular, by making the rotation speed of the first transport paddle 31d in the developing unit 31 faster than the second transport paddle 32a in the toner cartridge 32, the number of times the space formed inside the toner contacts the communication port 33 is reduced. Thus, by increasing the number of times the first transport paddle 31d pushes the control valve 34, the number of times of supplying the toner through the communication port 33 can be increased.
Further, the amount of supply / discharge due to the movement of the toner can be adjusted by the number of the communication ports 33. Therefore, one or more communication ports 33 can be provided. The number of the communication ports 33 is appropriately determined according to the image forming speed of the image forming apparatus main body.
Moreover, the control valve 34 provided corresponding to the communication port 33 is provided in the shape of a comb, and the adjacent control valves 34 can be operated alternately. This is because the paddle film of the first transport paddle 31d is provided in every other comb tooth shape corresponding to the comb tooth shaped control valve 34, and all the control valves 34 are composed of two paddle films. The control valves 34 can be operated alternately corresponding to the above. By alternately operating, the toner can be discharged evenly without forming a toner dead space in the developing unit 31.

FIG. 11 is a schematic diagram illustrating a configuration of a first transport paddle disposed in a developing device provided in an image forming apparatus that is an embodiment of the present invention. Specifically, it is a perspective view of the first transport paddle.
The first transport paddle 31d has a film 31d-1 and a film 31d-2 attached to an axis having a quadrangular cross section, and two of them extend in opposite directions on opposite surfaces. This opposing film 31d-1 has a concavo-convex shape (comb shape), and is a shape that shifts the two convex portions. In this way, adjacent control valves 34 can be driven alternately. The uneven portion corresponds to the position of the communication port 33, and the control valve 34 provided in the communication port 33 has a length that allows the convex portion of the film to be pushed in, and the concave portion has a shape that does not contact the control valve 34.
Further, the base portion of the convex portion of the film is formed in a “C” shape so as to be wider than the leading end portion. A moving force is generated to cause horizontal agitation in the developing unit 31.
Further, as the first transport paddle 31d rotates, the convex portion of the film pushes the control valve 34 to return the toner below the control valve 34 to the toner cartridge 32 side. This movement will be described later.
Since the first transport paddle 31d is set so as to rotate faster than the second transport paddle 32a, the control valve 34 is operated several times by the first transport paddle 31d within the time that the cartridge has space. The toner can be returned to the toner cartridge 32 efficiently.
When the convex portion of the film passes through the control valve 34, the control valve 34 is released from the pressing force and returns to its original state by elasticity, and the toner on the control valve 34 is sent to the developing unit 31 side, and the toner is placed below the control valve 34. A space for drawing the toner in the cartridge 32 is formed.
By shifting the convex portions of the two films 31d-1 of the first transport paddle 31d, the control valve 34 is alternately pushed and released, that is, the adjacent control valves 34 are driven alternately so that the developing unit The movement of the toner in the toner 31 is improved, and the circulation property with the toner in the toner cartridge 32 can be improved.

Here, by adopting the first conveyance paddle 31d having the two comb-shaped films as described above, the toner circulation and the lateral agitation are improved. However, in the case of only the two sheets, the communication port 33 is used. The amount of toner tends to increase, and the toner surface in the developing unit 31 undulates in the vertical direction to form peaks and valleys. If the communication port 33 is clogged, the supply of toner from the toner cartridge 32 is hindered, and the amount of toner supplied to the entire developing unit 31 is reduced. Further, since the toner flows from the toner cartridge 32 in the vicinity of the bottom of the toner peak, a phenomenon that the toner agitation uniformity is not ensured is observed. In order to improve this point, as a result of investigation, between the two comb-like films, the comb-like film 31d-1 and the angle of 90 degrees are shorter than the convex portion of the comb-like film. By adding a film without unevenness, that is, a rectangular film film 31d-2 to the first transport paddle 31d, the toner pile at the communication port 33 is broken and the toner surface in the developing unit 31 is made almost horizontal. I was able to.
As described above, in the first transport paddle, the second and third transports of the toner cartridge 32 are performed by disposing the rectangular film film 31d-2 between the two comb-shaped films 31d-1. Both the replenishment amount of toner from the films of the paddles 32a and 32b and the return amount of toner to the toner cartridge 32 are stable, and a sufficient circulation action can be achieved. In addition, since a local toner flow is not formed, uniform agitation can be maintained in the developing unit 31.

The width of the control valve 34 is 0 mm to 20 mm larger than the width of the communication port 33. When the control valve 34 is smaller than the communication port 33, the communication port 33 to which toner is supplied is blocked by the toner on the developing unit 31 side, so that it is difficult to supply toner. Further, in discharging the toner, toner enters between the control valve 34 and the communication port 33, and a large amount of toner is discharged from the developing unit 31 side to the toner cartridge 32 side through the communication port 33 by discharging the inserted toner. However, since the width of the control valve 34 is reduced, a large amount of toner is discharged and the toner in the developing unit 31 is reduced.
On the other hand, toner is discharged from the side of the control valve 34 between the control valve 34 and the communication port 33 through the communication port 33 when the first transport paddle 31d is pushed. For this reason, when the width of the control valve 34 is larger than the communication port 33, the amount of toner that wraps around the communication port 33 is reduced, the amount of discharged toner is reduced, and toner replacement is reduced. The toner supplied from the communication port 33 moves downward from the communication port 33 and is mixed with the toner under the control valve 34. Therefore, when the width of the control valve 34 is increased, the number of supplied toners is reduced, and the homogeneity due to the mixing of the toner is lowered.
For these reasons, the width of the control valve 34 is at least the width of the communication port 33 and less than 20 mm. By setting this width, it is possible to easily control the supply / discharge of the toner, and to improve the homogeneity due to the mixing of the toner after the supply.

The interval between the control valves 34 is 2 mm to 20 mm. When the distance between the control valves 34 is less than 2 mm, the amount of toner entering between the control valve 34 and the communication port 33 is small, and the amount of toner that can be discharged is small. Further, if it exceeds 20 mm, the number of communication ports 33 that can be provided decreases, and the amount of toner supplied and discharged decreases.
The length of the control valve 34 is 10 mm to 25 mm. The size of the space formed between the control valve 34 and the communication port 33 is determined by the length of the control valve 34. Therefore, if the control valve 34 is less than 10 mm, the amount of discharged toner is reduced, and toner replacement is insufficient. If it exceeds 25 mm, the amount to be discharged increases and the amount of toner in the developing hopper decreases.
Further, the angle of the control valve 34 is set to 10 ° to 45 °. The size of the space formed between the control valve 34 and the communication port 33 is determined by the angle of the control valve 34. Therefore, if the angle of the control valve 34 is less than 10 °, the amount of toner discharged becomes small, and the replacement of toner becomes insufficient. When the angle exceeds 45 °, the amount to be discharged increases and the amount of toner in the developing hopper decreases.

Here, the developing device 30 will be further described in detail. The developing device 30 includes a developing roller 31a that rotates while carrying toner on the surface to develop an electrostatic latent image on the surface of the photoreceptor belt 11, and a toner first transport paddle 31d that rotates to pump up and stir the toner. And a toner cartridge 32 for containing toner. The reason why it is divided into two units in this way is that the developing unit 31 has durability that can withstand even if the toner cartridge 32 is replaced several times.
12A and 12B are schematic views showing the configuration of the communication port in the developing device provided in the image forming apparatus according to the embodiment of the present invention. FIG. 12A shows the configuration on the developing unit side, and FIG. 12B shows the toner cartridge. The structure of the side is shown. A slide shutter 31j is provided outside the housing of the developing unit 31, and an elastic member 31k is attached to the slide shutter 31j. The communication port 33 of the developing unit 31 is opened and closed by opening and closing the slide shutter 31j. Further, the toner cartridge 32 side prevents the toner from spilling from the elastic member 32d having an opening corresponding to the communication port 33 provided in the housing, and the communication port 33, or can replenish the toner. A slide shutter 32c to be opened and a fixed seal 32e for fixing them to the housing are provided.
By arranging the toner cartridge 32 in the developing device, the slide shutter 31j on the developing unit 31 side is opened, and the slide shutter 32c on the toner cartridge 32 side is opened, so that a communication port 33 through which toner can pass is formed.

There are a plurality of communication ports 33 on the developing unit 31 side. A slide shutter 31j with an elastic member 31k attached is provided between the developing unit 31 and the toner cartridge 32, and the developing unit 31 is moved by moving the slide shutter 31j. The communication port 33 provided in the housing is opened and closed. When there is no toner cartridge 32 or when it is not attached to the image forming apparatus main body, the communication port 33 is closed with a slide shutter to prevent toner from spilling from the developing unit 31.
Further, when the developing unit 31 is not provided or the toner cartridge 32 is not attached to the image forming apparatus main body, the communication port 33 is closed in order to prevent the toner from spilling out from the toner cartridge 32. A slide shutter 32c is provided. The elastic member 32d is preferably a foamed material such as urethane resin or silicone resin.
As shown in FIG. 12, a window portion 31m opened to the slide shutter 31j is provided corresponding to the communication port 33 provided in the developing unit 31 and the toner cartridge 32. When the communication port 33 is closed, the communication port 33 is closed where there is no window 31m of the slide shutter 31j. The entire communication port 33 is communicated.

In the image forming apparatus 1, the developing device 30 conveys the toner to the developer supply roller 31b while stirring the toner with the first conveyance paddle 31d in the developing unit 31, and the supply roller 31b rubs against the developing roller 31a. At the same time, the toner is rubbed and frictionally charged to charge the toner. The charged toner is attracted to the developing roller 31a with a mirror image force and conveyed. Thereafter, the amount of toner conveyed to the development area is regulated by the regulation roller 31c. A thin toner layer formed on the developing roller 31a is developed on the photosensitive belt with a developing bias in the developing region.
At this time, the toner rubbed against the developing roller 31a by the supply roller 31b receives a large pressing force, and the irregularities on the surface of the toner are scraped to become spherical and increase the adhesion force of the toner. Further, the external additive on the surface of the toner is buried by this pressing force and the fluidity is lowered, and further, the charge amount cannot be adjusted by the external additive, so that the charge amount is changed. Under these influences, the developing property of the toner is lowered, and further, the transfer property and the cleaning property are lowered.
Thus, the amount of deteriorated toner increases in the developing hopper 311 and the toner in the developing unit 31 decreases because the toner is consumed by the development. Therefore, the toner is supplied from the toner cartridge 32 to the developing unit 31 through the communication port 33. In the toner cartridge 32, a second transport paddle 32a and a third transport paddle 32b whose tips are in sliding contact with the inner wall of the toner cartridge main body 32 are provided in the first storage chamber 321 and the second storage chamber 322, respectively. Alternatively, the third transport paddles 32 a and 32 b rotate to push the toner toward the developing unit 31, and the toner is supplied to the developing unit 31 from the communication port 33.

Further, the toner in the developing unit 31 is discharged to the toner cartridge 32 through the communication port 33, and the toner is mixed with the toner in the toner cartridge 32. A large amount of unused toner is stored in the toner cartridge 32 and is mixed with the deteriorated toner in the developing unit 31. As a result of this mixing, the external additive present in large amounts on the surface of the unused toner is redistributed to the deteriorated toner, whereby the charge amount and fluidity of the deteriorated toner become close to those of the original unused toner. This is because the toner discharged from the developing unit 31 to the first storage chamber 321 is further transported to the second storage chamber 322 by the second transport paddle 32a, and then to the first storage chamber 321 by the third transport paddle. Returned to During this time, the external additive is redistributed.
The toner approaching the original unused state is supplied again from the first storage chamber 321 of the toner cartridge 32 to the developing unit 31. A high-quality image can be obtained over a long period of time by forming a thin layer on the developing roller 31a and developing the toner with the toner that has approached the original state and the unused toner.

By the way, as for the lubricant removing roller 31e, as in the example of FIG. 5, the toner containing the lubricant conveyed onto the developing roller 31a is removed and moved to the developing hopper 311 from which the developing of this configuration is performed. In the apparatus 30, since the toner circulation property is excellent, the toner can be moved in the range from the developing hopper 311 to the toner cartridge 32. Since there is a sufficient chance of contact with the toner not adhering the lubricant, the toner can be more actively stabilized.
Various embodiments will be described below.
The sponge roller used for the lubricant removing roller 31e is constructed by covering the periphery of a core metal such as stainless steel with a cylindrical foam, and the foam is made of polyurethane, polyethylene, melamine, silicon rubber or the like. it can.
When the lubricant removing roller 31e is composed of a sponge roller, various properties of the sponge roller were evaluated for the removability of the toner containing the lubricant and the lubricant adhering to the developing roller 31a. It was found that there is an appropriate range for the 25% compression load (JIS-K6767), which is the characteristic of the thickness, and the cell diameter of the sponge.

A sponge with a 25% compressive load between 0.015 MPa and 0.5 MPa is good, and if it is lower than that, the pressure on the developing roller 31a is lowered, and the ability to scrape off the lubricant becomes insufficient. On the other hand, if it is high, it is difficult to secure a contact area, and vibration is likely to occur, so that it is difficult to obtain stable contact conditions. The compressive load is in a characteristic range that is almost normal to the sponge, but the cell diameter, which is another characteristic, is necessarily required to be in the following range.
In other words, the average cell diameter is preferably in the range of 0.1 mm to 2 mm. If the average cell diameter is smaller than that, the ability to hold the removed toner on the surface of the sponge roller is easily obstructed because the cells are buried with the toner. As a result, the effect cannot be expected.
The reason why the lubricant adhering to the developing roller 31a is mechanically removed is that the cells on the surface of the sponge roller are partitioned between the cells, and the wall surface portion forming the skeleton of the cell structure is in contact with the developing roller 31a. . Therefore, if the cell diameter is small, the wall surface is thin and the strength is not high, so that the removal performance is insufficient.
On the other hand, when the cell diameter of the sponge roller is large, a situation occurs in which the wall portion does not contact within the nip width passage time between the lubricant removing sponge roller 31e and the developing roller 31a, and the lubricant removal residue occurs. Since the nip width between the developing roller 31a and the sponge roller is desirably set to 1 to 3 mm, the upper limit of the cell diameter is 2 mm. Here, the cell diameter of the sponge is generally expressed as an average cell diameter. It does not mean that it may vary widely within the range of the cell diameter. It is clear that the smaller the variation of the individual cell diameters relative to the center value is, the more desirable it is in terms of the stability of the lubricant removal. However, it is not necessary to suppress the variation excessively, and the stability of the removal performance can be secured if the sponge is produced by the current normal manufacturing method.

Here, several methods for evaluating lubricant removability will be described.
A normal paper passing test is performed with the conditions for applying the lubricant on the photoconductor and the image area of the toner to be developed fixed, and quantitative analysis of the lubricant adhering to the developing roller 31a over time is performed. Alternatively, the location around the developing roller 31a is determined in advance, and the toner is collected there to quantitatively analyze the lubricant contained in the toner. As a substitute for the amount of lubricant adhering to the developing roller 31a, it is possible to estimate to some extent by a method of measuring the friction coefficient of the surface of the developing roller 31a.
In this case, the friction coefficient tends to saturate to the lower limit value when the lubricant adheres to a certain area or more. Therefore, it is preferable to examine the changing process from the initial friction coefficient to the lower limit value.
When the developing roller 31a used was a metal roller surface layer coated with melamine resin, the change in the friction coefficient was from the initial 0.5 to the lower limit of 0.1. Note that, when measuring the friction coefficient, a PPC quality paper was used as the friction partner.
It is also possible to examine the change with time using the image and development characteristics as evaluation targets.
The evaluation is made quantitatively by looking at the density of the solid image, the difference between the density at the front end and the density at the rear end, or by the change (decrease) in the amount of toner attached to the developing roller 31a.
The removal of the lubricant increases the probability that the lubricant on the surface moves as the number of objects in contact with the surface of the developing roller 31a increases (the more the number of contacts).
Lubricant can be removed efficiently by providing an action of assisting the removal of the lubricant adhering to the developing roller 31a.
Here, the assisting function is assigned to the toner of the hopper that is not attached with much lubricant.

In FIG. 5, the first transport paddle 31d rotates counterclockwise to the developing hopper 311 and feeds the toner to the supply roller 31b. The position of the supply roller 31b is arranged below the developing unit 31, and The lubricant removing roller 31e is arranged at a substantially horizontal position with respect to the developing roller 31a so that the toner pumped up by the transport paddle 31d contacts the lubricant removing roller 31e. That is, toner is sent from the first transport paddle 31d to both rollers 31b and 31e.
If the rotational direction of the lubricant removing roller 31e is clockwise, the toner conveyed from the developing hopper 311 moves clockwise on the lubricant removing roller 31e and enters the nip with the developing roller 31a. The developing roller 31a and the lubricant removing roller 31e are rubbed at their nips, and during that time, the delivery of the lubricant is performed from the more lubricant to the lesser.
When there is only the toner layer conveyed by the developing roller 31a between the developing roller 31a and the lubricant removing roller 31e, the toner layer contains a lubricant, so the surface of the lubricant removing roller 31e is lubricated. As the agent adheres and accumulates, the ability to remove the lubricant from the surface of the developing roller 31a gradually decreases, and finally the ability to remove the lubricant is lost.
In this embodiment, since the toner of the developing hopper 311 is always poured between the developing roller 31a and the lubricant removing roller 31e, the chance of contact with the lubricant adhered to the surface of the developing roller 31a by the toner increases, and the developing roller The lubricant can be easily removed from 31a, and the lubricant adhering to the surface of the lubricant removing roller 31e is also kept low, so that the ability to remove the lubricant is maintained at any time.

Although the rotation direction of the lubricant removing roller 31e is clockwise in the above description, the toner in the developing hopper 311 is transferred from the transport paddle 31d to the lubricant removing roller 31e by changing the arrangement of the scraping member 31f upward. The same effect can be obtained.
In order to efficiently move the toner containing the lubricant conveyed from the developing roller 31a by the lubricant removing roller 31e to the developing hopper 311 from the lubricant removing roller 31e, the toner on the surface thereof is brought into contact with the lubricant removing roller 31e. A lubricant removing contact member 31f is provided to scrape off.
The amount of biting between the lubricant removing contact member 31f and the lubricant removing roller 31e is set to about 0.5 mm to 3 mm so that the toner can be scraped off sufficiently and the surface of the lubricant removing roller 31e is not damaged. To do.
It is desirable that the lubricant removing contact member 31f be disposed so as not to impair the movement of the toner by providing an angle so that the scraped toner does not stay and easily falls to the developing hopper 311.

Further, the developer removing contact member 31f is made of a material such as a metal plate or a resin plate and has no functional problem.
If toner in the developing hopper 311 can be transported by the first transport paddle 31d to the nip portion between the developer removal contact member 31f and the lubricant removal roller 31e, toner containing lubricant can be prevented from staying in the nip. So the effect goes up further.
The toner scraped off by the developer removal contact member 31f is mixed and stirred in the developing hopper 311 by the stirring action of the surrounding toner and the first transport paddle 31d, and the toner containing a large amount of lubricant is changed to the surrounding toner. By diffusing the lubricant, the amount of the lubricant is averaged over the entire toner up to an unaffected level, and the most adhering to the developing roller 31a can be prevented.
In the previous embodiment, when the developing roller 31a rotates in the direction opposite to the clockwise direction and the lubricant removing roller 31e rotates in the clockwise direction, that is, the lubricant removing roller 31e is rotated in the rotating direction with respect to the developing roller 31a. An example of rotating in the above has been described. Here, an example in which the lubricant removing roller 31e rotates in the counter direction with respect to the developing roller 31a will be described.
Similarly, when the developing roller 31a is rotated counterclockwise and the lubricant removing roller 31e is also rotated counterclockwise, the lubricant removing roller 31e rotates in the counter direction at the contact portion with the developing roller 31a. . Generally, rotating the lubricant removing roller 31e in the counter direction has a higher ability to remove the toner containing the lubricant and the lubricant adhering to the surface of the developing roller 31a. Further, the merit of rotating in this direction is that the toner including the lubricant moved from the developing roller 31a to the removing roller 31e can be conveyed on the lubricant removing roller 31e in a direction away from the developing roller 31a, and the removing contact member 31f is It can be arranged that the conveyed toner can be easily placed on the developing hopper 311.

Further, the toner supplied to the lubricant removing roller 31e by the first transport paddle 31d is frictionally charged at the nip between the removing roller 31e and the developing roller 31a, and is preliminarily supplied from the removing roller 31e to the developing roller 31a. It is possible to supplement supply shortage by supplementing supply before the roller 31b.
At this time, it is desirable that the rotational linear speed ratio of the removing roller 31e to the developing roller 31a is 0.5 times to 2 times. This is a linear speed ratio that can effectively extract the removal capability even with respect to the cell diameter of the sponge of the removal roller 31e. However, if the linear speed ratio is increased too much, heat is generated, and heat stress is applied to the toner to lower the fluidity, or the lubricant is softened by changing the heat to make it easier to adhere to the developing roller 31a. Needs to be about double speed.
In particular, the rotation direction of the supply roller 31b is not defined, and the supply roller 31b can be selected in either the counter direction or the follow-up direction with respect to the developing roller 31a.
If it is strong, the supply roller 31b is advantageous in replenishment / preliminary charging because the relative speed of sliding with the developing roller 31a is higher in the counter direction, so the supply roller 31b usually also selects the counter direction. Things are common.

Next, a case will be described in which there is a restriction on the layout of the developing device 30 and the image forming device, and the lubricant removal roller 31e cannot select the counter direction as in the previous section.
When the lubricant removing roller 31e is rotated in the direction of rotation with respect to the developing roller 31a, the toner of the developing hopper 311 is supplied by the first transport paddle 31d in order to improve the ability to remove the lubricant adhering to the developing roller 31a. In this case, since the rotation direction of the lubricant removing roller 31e is a clockwise direction, the supplied toner also moves in that direction. That is, the toner enters from the entrance side (above the nip) of the nip between the lubricant removing roller 31e and the developing roller 31a, and rubs with both rollers at the nip, so that the lubricant adhering to the developing roller 31a and the developing roller 31a In contact with the toner containing the lubricant conveyed above, the lubricant is transferred to the surface of the toner supplied from the developing hopper 311, and the nip exit side of the nip between the lubricant removing roller 31 e and the developing roller 31 a (nip Is discharged in the direction below that (below the lower side). The toner adhering to the lubricant removing roller 31e as it is is scraped off below the developing hopper 311 by the removing contact member 31f.
Since there is a toner supply roller 31b below the lubricant removal roller 31e, the toner containing the lubricant discharged from the lubricant removal roller 31e directly falls on the supply roller 31b, and the rotation direction of the supply roller 31b is the developing roller 31a. In this case, since the toner is supplied to the developing roller 31a, it is necessary to rotate the supply roller 31b in the counter direction with the developing roller 31a. With such a configuration, it is possible to effectively prevent the lubricant from adhering to the developing roller 31a as in the previous section. At this time, the supply roller 31b may be provided with a removal contact member 31f similar to the lubricant removal roller 31e.

Since the rotation speed of the removal roller 31e is in the rotation direction with the developing roller 31a, the linear speed ratio at the contact portion with the developing roller 31a is at least 1.1 times faster than the developing roller 31a and not more than 3 times speed.
This is a linear speed ratio that can effectively extract the removal capability even with respect to the cell diameter of the sponge of the removal roller 31e.
However, if the linear speed ratio is increased too much, heat is generated, and heat stress is applied to the toner to lower the fluidity, or the lubricant is softened by changing the heat to make it easier to adhere to the developing roller 31a. Needs to be about double speed.
The merit of this method is that the lubricant removing roller 31e rotates in the follower direction with respect to the developing roller 31a and at a higher linear speed than the developing roller 31a. Since the amount of toner passing through the nip can be increased, the chance of contact between the toner and the lubricant can be increased, and more lubricant can be removed even if the linear speed ratio is not large.
Further, since the rotation directions of the supply roller 31b and the lubricant removal roller 31e are opposite, the respective drive gears can be directly connected, the gear arrangement can be facilitated, and the drive system space can be reduced.
In this embodiment, the toner containing the lubricant is not only mechanically removed from the developing roller 31a to the lubricant removing roller 31e, but the removal performance is improved by moving the toner by the action of an electric field. The lubricant removing roller 31e has a volume resistance of 10 5 Ωcm to 10 8 Ωcm so as to have semiconductivity.
Generally, the resistance is adjusted by containing an ion conductive material such as carbon black, metal powder, or a surfactant.
In order to draw most of the toner carried on the developing roller 31a through the developing area toward the lubricant removing roller 31e, a potential difference of 200V to 400V is provided from the analogy of the developing action on the photosensitive member. Can be achieved.
That is, when the charging polarity of the toner is negative, when the developing roller 31a is 0V, the toner on the developing roller 31a can be removed by applying + 200V to + 400V to the removing roller 31e. When the developing roller 31a performs a developing operation on the photosensitive member and a developing bias is applied, for example, when a developing bias of −400V is applied, the removal roller 31e is changed from −200V to 0V. It ’s fine.
As described above, the toner removability can be improved more than the mechanical action, and the lubricant can be prevented from adhering to the developing roller 31a.

In the case of a one-component toner, an additive composed of fine particles is attached around the toner particles for the purpose of stabilizing the properties of the toner or adding better properties.
It is not externally kneaded into the toner particles, but is attached to the toner particle surfaces, so it is called an external additive. As described above, the external additive has a small particle size, and the toner has a particle size of about 4 to 10 μm, whereas the primary additive has a primary particle size of 10 nm to several tens of nm compared to the toner. The amount of the additive is not so large, but the surface area of the additive is relatively large.
Therefore, the effect of removing the lubricant by the adsorbing action of the lubricant by the additive is large, and the amount of the additive added to the toner greatly affects the effect of removing the lubricant.
There are various kinds of inorganic fine particles used for the external additive, and examples of frequently used fine particles include hydrophobic silica, titanium oxide, aluminum oxide, silicon carbide, cerium oxide, and boron nitride.
One type of external additive may be used, but the characteristics such as chargeability and fluidity differ depending on the material of each type of external additive. There are many.
It is not clear whether there is a difference in the lubricant adsorption action for each additive type, but since the particle size of the additive fine particles is in the same order, the surface area is considered to be the same level. Assuming equivalent adsorption action.
When the additive removal pattern was changed and the lubricant removal performance was evaluated by the method described above, a toner cartridge that is replaced by using 15K sheets is used here. When the toner cartridge is renewed, the supplied toner contains no lubricant, which is advantageous for preventing the lubricant from adhering to the developing roller 31a. If the density does not decrease until the cartridge is replaced, the life can be extended. I can think about it.

Table 1 shows the actual evaluation results for a toner containing only hydrophobic silica as an external additive.

Table 2 shows the actual evaluation results for the hydrophobic silica + titanium oxide toner as the external additive.

という結果が得られた。 Table 3 shows the actual evaluation results for the toner of hydrophobic silica + titanium oxide + aluminum oxide as the external additive.

The result was obtained.

That is, when the total amount of the additive material is less than 1.2 parts by weight, the action of removing the lubricant is lowered, the adhesion of the lubricant to the developing roller 31a is advanced, the toner conveying force of the developing roller 31a is lowered, and the development is performed. It is considered that a decrease in concentration has occurred.
This is because the coverage ratio of the additive on the toner surface changes depending on the amount of the additive, and the additive removal action is considered to be superior to the surface of the toner particles because the lubricant removal action is considered to be superior. If the coverage is not increased to some extent, the ability to remove the lubricant is insufficient, and if the coverage is above a certain level, the ability to remove the lubricant reaches a level that satisfies the target.
In addition, for reasons of development characteristics, there are cases where more external additives are prescribed, but instead of preventing a decrease in density due to insufficient removal of the lubricant, the amount of additives released from the toner increases, so that the surface of the photoconductor is increased. Filming may occur due to adhesion of additives.
In the case of using only hydrophobized silica, if it exceeds 7 parts by weight, even if the contact pressure between the developing roller 31a and the photoconductor 11 is lowered as much as possible, or even if a lubricant is applied to the photoconductor 11, they are removed. Thus, the filming occurred.
In the system in which other additives were mixed with hydrophobized silica, the filming did not occur immediately after exceeding 7 parts by weight, but basically there was no room, and images with a high area ratio were kept. In this case, filming occurred with an additive amount of about 7.5 parts by weight.
From these series of studies, the proper range of the amount of the external additive is 1 as the toner used in the image forming apparatus having this configuration, which draws out the lubricant removability and does not result in excessive lubricant application conditions. It was confirmed that it was in the range of 2 to 7 parts by weight.
By selecting this range, it is possible to prevent both problems such as density reduction and filming caused by adhesion of the lubricant.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. It is the schematic which shows the structure of a lubricant application apparatus in detail. 1 is a schematic diagram illustrating a configuration of a developing device provided in an image forming apparatus according to an embodiment of the present invention. 1 is a schematic diagram illustrating a configuration of a developing device provided in an image forming apparatus according to an embodiment of the present invention. 1 is a schematic diagram illustrating a configuration of a developing device provided in an image forming apparatus according to an embodiment of the present invention. It is the schematic which shows the structure of the control valve arrange | positioned at the image development unit in the image development apparatus of this invention. It is the schematic which shows the shape of a communicating port. FIG. 4 is a schematic diagram for explaining a state in which toner is supplied from a toner cartridge side to a developing unit. FIG. 6 is a schematic diagram for explaining a state in which toner on the toner cartridge side is supplied. FIG. 7 is a schematic diagram for explaining a state of toner movement between a developing unit and a toner cartridge. FIG. 6 is a schematic diagram for explaining a state of toner movement between a developing unit and a toner cartridge. FIG. 6 is a schematic diagram for explaining a state of toner movement between a developing unit and a toner cartridge. FIG. 3 is a schematic diagram illustrating a configuration of a first transport paddle disposed in a developing device provided in an image forming apparatus that is an embodiment of the present invention. 4A and 4B are schematic diagrams illustrating a configuration of a communication port in a developing device provided in an image forming apparatus according to an embodiment of the present invention, in which FIG. Show. It is the schematic which shows the structure of the conventional image development apparatus. It is the schematic which shows the structure of the conventional image development apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 11 Photoconductor 12 Photoconductor cleaning apparatus 12a Cleaning blade 12b Application brush 12c Lubricant bar 12d Lubricant pressurizing means (weight)
13 First charging means 14 Driving roller (photosensitive member)
15, 16 Followed roller (photosensitive member)
20 exposure means 21 registration roller 25 paper feed roller 26 contact / separation mechanism 30 developing device 31 developing unit 311 developing hopper 31a developing roller 31b supply roller 31c regulating roller 31d first transport paddle 31d-1, 31d-2 film 31e developer removing member (roller)
31f Developer removing contact member 31g Toner stirring member 31h Inlet seal 31j Slide shutter 31k Elastic member 31m Window 32 Toner cartridge 321 First storage chamber 322 Second storage chamber 32a Second transport paddle 32b Third transport paddle 32c Slide shutter 32d Elastic member 32e Fixed seal 33 Communication port 34 Control valve 34a Support portion 34b Film 35 Rib 40 Intermediate transfer belt unit 41 Intermediate transfer belt 42 Belt cleaning unit 43 Mark sensor 44 Drive roller (intermediate transfer belt)
45 Primary transfer bias rollers 46, 47 Followed roller 49 Belt position detection mark 50 Secondary transfer unit 51 Secondary transfer bias roller 60 Fixing means 70 Double-sided transport device 80 Paper feed device 81 Paper feed roller 83 Manual feed tray 90 Transfer material

Claims (11)

An image carrier for forming a latent image;
A charging device for uniformly charging the surface of the image carrier;
An exposure device that exposes a charged image carrier surface to form a latent image;
A contact one-component developing device for bringing a toner carrier into contact with an image carrier, supplying toner to a latent image formed on the image carrier, and developing the toner;
A transfer device for transferring the toner image of the image carrier directly to a recording medium or transferring the toner image on the intermediate transfer body to a recording medium;
A cleaning device for removing toner remaining on the image bearing member or the intermediate transfer member;
A fixing device for fixing the toner image on the recording medium, and
In the image forming apparatus having means for applying a lubricant to the image carrier,
The contact one-component developing device is:
Constructed by arranging toner cartridges for supplying toner to the developing unit,
The developing unit is
A developing hopper for collecting toner replenished from the toner cartridge;
A transport paddle for sending the toner in the developing hopper to the toner supply member;
A toner supply member for supplying the toner to the toner carrier;
A toner layer thickness regulating member that regulates the toner on the toner carrier to form a toner layer;
A toner carrier that develops the toner layer regulated by the toner layer thickness regulating member in contact with the image carrier;
An image in which a toner layer thickness regulating member, a toner supply member, and a lubricant removing member are arranged in contact with the periphery of the toner carrying member from the downstream to the upstream in the rotation direction of the toner carrying member. Forming equipment. The image forming apparatus according to claim 1,
The contact one-component developing device is:
A communication port through which the toner passes between the toner cartridge and the developing unit;
An image forming apparatus comprising a control valve on an inner surface of the developing hopper in order to control the amount of toner to be passed therethrough. The image forming apparatus according to claim 1, wherein
The lubricant removing member is constituted by a sponge roller, and the diameter of the foam cell on the surface thereof is in the range of 0.1 mm to 2 mm. The image forming apparatus according to any one of claims 1 to 3,
The toner in the developing hopper is supplied to the surface of the lubricant removing member. The image forming apparatus according to claim 1,
An image forming apparatus comprising: a lubricant removing contact member that contacts the surface of the lubricant removing member. In the image forming apparatus according to claim 5,
An image forming apparatus, wherein toner in the developing hopper is supplied to a surface of the lubricant removing member and a contact portion of the lubricant removing contact member. The image forming apparatus according to any one of claims 3 to 6,
The lubricant removing member is rotated so that the rotation direction of the lubricant removing member is opposite (counter direction) at the contact portion with respect to the rotation direction of the toner carrier, and the lubricant An image forming apparatus, wherein the peripheral speed of the removing member is a peripheral speed ratio of 0.5 to 2 times the peripheral speed of the toner carrier. The image forming apparatus according to any one of claims 3 to 6,
The rotation direction of the toner supply member is the opposite direction (counter direction) at the contact portion with respect to the rotation direction of the toner carrier, and the lubrication is performed with respect to the rotation direction of the toner carrier. The lubricant removing member is rotated so that the rotation direction of the agent removing member is the same direction (the direction of rotation) at the contact portion, and the peripheral speed of the lubricant removing member is An image forming apparatus having a peripheral speed ratio of 1.1 to 3 times the speed. The image forming apparatus according to claim 1,
In order to form an electric field in which toner moves from the toner carrying member to the lubricant removing member, voltage applying means for applying a voltage is provided between the toner carrying member and the lubricant removing member. Image forming apparatus. The image forming apparatus according to claim 1,
The image forming apparatus according to claim 1, wherein an additive amount of the external additive of the toner used in the developing device is between 1.2 parts by weight and 7 parts by weight with respect to the toner. The image forming apparatus according to claim 1,
An image forming apparatus comprising: a toner stirring member provided below the lubricant removing member.

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