JP2008107427A - One-component developing device, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a long-life developing device causing no image quality deterioration over a long period by effectively using a doctor roller without continuously using the same surface of the doctor roller, and to provide a process cartridge and an image forming apparatus. <P>SOLUTION: The one-component developing device 30 includes: a developing sleeve 31a configured to stick one-component toner to a photoreceptor 10 formed with an electrostatic latent image to thereby visualize the electrostatic latent image; a toner supply roller 31b that rotates in contact with the developing sleeve 31a to supply the toner; and the doctor roller 31c that controls the sticking amount of the toner applied on the developing sleeve 31a, wherein the one-component developing device 30 is provided with a means for detecting the position of the doctor roller 31a, and a means for storing the number of used sheets of toner cartridges at the contact position detected by the means. When a predetermined number of sheets are used at the contact position detected by the means, the contact position of the doctor roller 31c is changed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a one-component developing device used for image formation by an electrostatic copying process such as a copying machine, a facsimile machine, and a printer, and also relates to a process cartridge and an image forming apparatus using the 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, originals including graphs created with a personal computer are output by a printer and used as presentation materials. Opportunities to copy sheets are increasing. Printer output images are mostly solid images, line images, and halftone images. Accordingly, market demands for image quality are changing, and demands for high reliability and the like are further increasing.
Developers used in electrophotographic systems such as electrophotography, electrostatic recording, and electrostatic printing are, for example, an image carrier (typically a photoreceptor) on which an electrostatic latent image is formed in the developing process. Then, the toner is transferred from the photosensitive member to a transfer medium such as transfer paper in the transfer process, and then fixed on the paper surface in the fixing process. 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 the two-component developer, the developer deteriorates due to the 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 drawback that the developing device is increased in size. On the other hand, one-component developers have the advantage that the device can be miniaturized, etc., and are easy to use in any environment (low temperature, low humidity, high temperature, high humidity), etc. 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 sleeve 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 many cases, it has been put into practical use in small printers. In contrast, in the non-magnetic one-component development method using a non-magnetic one-component agent, since the toner does not have a magnetic force, the toner supply roller or the like is pressed against the developing sleeve to supply the toner onto the developing sleeve, and electrostatic 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 sleeve. 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 sleeve 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 / conveying means such as 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 sleeve, the toner is thinned by the layer thickness regulating member and developed, and the toner and the friction charging member such as the developing sleeve 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 be larger than that in 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. .

In order to solve this problem, in Patent Document 1, the developing sleeve is provided with a conductive resin layer having the same charging polarity as the charging polarity of the developer on the surface, and the conductive resin layer is at least a binder resin. , A developing device containing a conductive fine powder and a charge control agent, wherein the rotation center X of the stirring member is located below the horizontal plane H crossing the rotation center of the developing sleeve.
Patent Document 2 shows a configuration in which a reverse support valve is provided at the toner replenishing port to prevent the toner from returning (reversely flowing) to the cartridge side.
However, the technique disclosed above has a problem that it is difficult to stabilize the charging property and fluidity of the toner in the developing device over a long period of time.
Further, according to recent studies, when the toner in the cartridge flows into the developing unit 31, the toner is reversely charged due to the characteristics of the toner in the cartridge to cause background contamination, the developing sleeve of the developing unit, the entrance seal, It has been found that a slight difference in surface properties such as a toner regulating member is picked up to cause vertical streaky toner layer unevenness and cause unevenness in the image. Therefore, it is necessary to adjust the recovery operation at the time of cartridge replacement and the replenishment operation over time according to the characteristics of the toner of the cartridge.

The following document is an example of a one-component developing device provided with a cylindrical toner regulating member. However, in Patent Document 3, the toner regulating member is formed into a cylindrical shape, and the toner is regulated by contacting the developing sleeve to form a thin toner layer. However, a method has been proposed in which the contact position on the outer peripheral surface is changed by rotating the developing sleeve along with the developing sleeve during non-development operation.
The position where the cylindrical toner regulating member (doctor roller) is used is not specified, and the position used as the next contact surface changes depending on the distance the developing sleeve rotates. The doctor roller surface cannot be used. In particular, when unevenness occurs on the surface of the doctor roller over time, a position where the doctor roller is easy to stop and a position where it is difficult to stop is formed, and the position where the doctor roller is easy to stop is used exclusively.
Therefore, some parts will be worn, which will affect the life of the entire roller, and with a small number of sheets used, abnormal images such as white streaks will appear and the life of the entire unit will be reduced. I had decided.

In addition, there has been proposed a method in which the rotation angle of the developing sleeve is made substantially constant by driving the developing sleeve around.
However, it is not the accuracy that can determine the surface contact position of the doctor roller,
Moreover, since it is not managed which surface position is used, it becomes the same operation | movement as the above literature, and it is thought that the position of a doctor roller switches randomly after all.
Continuing the explanation about the wear on the surface of the doctor roller, it has been found that the amount of wear and the roughness of the wear are greatly affected by the state of the toner.
When the toner is almost unused, the toner has an appropriate particle size distribution, and its surface is coated with an external additive such as silica so that the toner does not aggregate. In this case, the wear on the surface of the doctor is uniformly worn on the entire contact surface, and the amount of wear is kept small because the bite into the doctor is small.
However, on the other hand, when the toner is deteriorated, that is, the number of particles having a large particle size increases, the amount of the external additive on the surface decreases and the toner particles are likely to aggregate. Wear increases rapidly and results in uneven wear.
When only the same surface position is used in a state where the toner is deteriorated, the roughness (unevenness) of the portion becomes rough, causing unevenness in the toner layer, causing severe unevenness and background stains in the image. Of course, once the surface of the doctor roller becomes in such a state, it will not be repaired, so even if the contact position on the surface of the doctor roller is changed, if the position is used again, stripes reappear in the image. It will be a thing.

  Therefore, in order to use the outer peripheral surface of the doctor roller evenly, a method for extending the life of the toner regulating member by always rotating the doctor roller during the developing operation is proposed in Reference 5. Then, since the impossibility torque of the development unit increases dramatically, the strength of the unit and the drive system must be increased, the size of the unit itself increases, and a powerful motor is required. The cost of will also rise dramatically.

JP 2005-062215 A JP 2002-162817 A JP 2004-271911 A Japanese Patent Laid-Open No. 2002-372861 JP 2001-253110 A

  Therefore, the present invention has been made in view of the above-mentioned problems, and the problem is that a long-lasting development without deterioration of image quality over a long period of time can be achieved by effectively using a doctor roller without using the same surface. An apparatus, a process cartridge, and an image forming apparatus are provided.

The features of the present invention, which is a means for solving the above problems, are listed below.
The one-component developing device of the present invention is configured to attach a one-component toner to an image carrier on which an electrostatic latent image is formed and to make the electrostatic latent image visible, and to contact the toner carrier. The toner supply rotating body for supplying the toner to the toner carrier, the toner conveying means for feeding the toner to the toner supply rotor, and the toner supplied from the toner supply rotor to the toner carrier. A one-component developing device comprising a cylindrical adhesion amount regulating member that contacts the toner carrier to regulate the adhesion amount, wherein the one-component developing device detects means for detecting the position of the adhesion amount regulating member; And a means for storing the number of sheets used at the contact position, and when the predetermined number of sheets used at the detected contact position is used, the contact position of the adhesion amount regulating member is changed.
The one-component developing device of the present invention further has a toner cartridge for storing a detachable replenishing toner, and can be replaced with a new toner cartridge after using the mounted toner cartridge. Means for storing the number of used sheets, and when the number of used toner cartridges exceeds a predetermined value, an operation of changing the contact position with a smaller number of used sheets is performed.
Further, the one-component developing device of the present invention further has means for storing the number of used cartridges for changing the contact position when the number of used toner cartridges exceeds a predetermined value. It is characterized by a long operating distance.
The one-component developing device of the present invention further includes means for detecting and storing the image area ratio of the output image, and when the image area ratio is equal to or less than a predetermined value, the use is less than the predetermined number. The operation of changing the contact position by the number of sheets is performed.
Further, the one-component developing device of the present invention further has means for detecting and storing the continuous number of sheets when performing continuous printing operation, and when the continuous number of sheets is equal to or greater than a predetermined value, It is characterized in that the operation of changing the contact position is performed with a small number of sheets used.
The one-component developing device of the present invention further includes means for detecting and storing the ambient temperature, and when the detected temperature is equal to or higher than a predetermined value, the contact position can be set with a smaller number of sheets used than the predetermined number. It is characterized by performing a changing operation.
The one-component developing device of the present invention further has means for detecting and storing the ambient temperature and humidity. When the detected humidity is a predetermined value or more, the contact is made with a smaller number than the predetermined number. An operation for changing the position is performed.
In the one-component developing device of the invention, the adhesion amount regulating member is further characterized in that a core layer is covered with a rubber layer, or a rubber layer and a resin coat layer thereon.
The one-component developing device of the present invention is further characterized in that the outermost layer of the adhesion amount regulating member contains fluororubber or fluororesin.
The one-component developing device of the present invention is further characterized in that the adhesion amount regulating member has a quadratic curve or a quartic curve with respect to the axis.
In the one-component developing device of the invention, it is further preferable that the rotation direction of the toner supply rotator is the same as the rotation direction of the toner carrier at a position where the toner supply rotator is in contact with the toner carrier. Features.

The process cartridge of the present invention uses at least the one-component developing device described above in a process cartridge that integrally supports at least the image carrier and the developing device and is detachable from the main body of the image forming device. It is characterized by that.
An image forming apparatus of the present invention includes an image carrier that carries a latent image, a charging device that uniformly charges the surface of the image carrier, an exposure device that writes an electrostatic latent image on the surface of the charged image carrier, A developing device that visualizes the electrostatic latent image formed on the surface of the image carrier, a transfer device that transfers the visible image on the surface of the image carrier directly or via an intermediate transfer member, and an image carrier An image forming apparatus comprising: a cleaning device that cleans a toner on a body; and a fixing device that fixes a visible image on a recording member with heat and / or pressure. A developing device is used.

As described above, the one-component developing device of the present invention can be used uniformly on the outer peripheral surface of the regulating member to prevent uneven wear and extend the life of the adhesion amount regulating member and the one-component developing device.
In the toner cartridge of the present invention, the toner cartridge can be replaced and the life can be extended by using a process cartridge in which the one-component developing device is integrally supported with the image carrier.
In the image forming apparatus of the present invention, the image quality can be stabilized over a long period of time by using this one-component developing device.

  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 a one-component developing apparatus according to the present invention.
FIG. 1 shows a type in which a control valve 34 is attached to improve the toner circulation between the toner cartridge 32 and the developing unit 31. In this circulation type, the toner is circulated and agitated between the toner cartridge 32 and the developing unit 31, so that the degree of deterioration is made uniform, and the deterioration of the toner can be suppressed with minimal toner deterioration without excessive deterioration. This is better for stability of properties. In addition, regarding the basic configuration of the developing unit 31, there is a type without the control valve 34 and a type in which the return to the toner cartridge 32 is reduced by a reversely supported valve. Either may be used.
This one-component developing device (hereinafter referred to as “developing device” unless otherwise specified) 30 includes a developing unit 31 and a developing unit 31 that develop the latent image of the photoconductor 11 as an image carrier with toner as a developer. And a toner cartridge 32 for supplying toner.
The developing unit 31 is opposed to the photosensitive member 11 and supplies a toner onto the developing sleeve 31a, which is a developer carrying member that conveys the toner to a developing region formed between the developing unit 31 and the developing sleeve 31a. A supply roller 31b that is a toner supply rotating body, a doctor roller 31c that is a cylindrical adhesion amount regulating member that regulates the amount of toner on the developing sleeve 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 one-component developer is used as the developer. In contrast to replacing the developer as will be described later, it is very difficult to separate the toner from the carrier once mixed with the two-component developer. In the case of a one-component developer, the developer in the toner cartridge 32 and the developing unit 31 is basically the same and can be replaced, and can be applied to the developing device 30 of the present invention. In particular, it is preferable to use a non-magnetic one-component developer even for a one-component developer. With magnetic one-component developers, developability can be controlled by the strength of magnetization depending on the amount of magnetic material, but with non-magnetic one-component developers, developability is greatly affected by the charge amount and fluidity of external additives. Is done. For this reason, the development characteristics vary greatly depending on the amount of the external additive on the toner surface, and it is difficult to maintain stable characteristics over a long period of time. Therefore, by using 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 receives a pressing force by the toner supply roller 31b and the doctor roller 31c in the developing unit 31. By receiving this pressing force, irregularities on the surface of the toner are chipped and the surface becomes smooth, and the adhesion to the photoconductor increases, making cleaning 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 is reduced. Similarly, the developability is improved by reducing the adhesion between the developing sleeve 31a and the toner. 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 unit 31 from the toner cartridge 32 to the developing unit 31. The toner cartridge 32 is mixed with non-deteriorated toner in the toner cartridge 32, the additive is transferred to the deteriorated toner and 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 unit 31.

FIG. 2 is a schematic view showing the structure of a control valve arranged in the developing unit in the one-component developing device of the present invention. 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 34a and disposed in the housing. As shown in FIG. 2, 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 sleeve 31a. The film may be plate-shaped. In addition, for 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. 3 is a diagram for schematically explaining a state in which toner is supplied from the toner cartridge side to the developing unit. The first transport paddle 31d rotates to hit the control valve 34, and the control valve 34 is pressed. Thereafter, the first transport paddle 31d passes, and the elastic control valve 34 is quickly bounced back, and at the same time, the toner pushed in from the toner cartridge 32 side passes through the communication port 33 and the developing unit 31. The toner is supplied by being attracted to the side.
FIG. 4 is a diagram for schematically explaining a state in which the toner is returned from the developing unit side to the toner cartridge. The toner cartridge 32 is transported to the first storage chamber 321 by the third transport paddle of the second storage chamber 322, and further transported to the developing unit 31 side by the second transport paddle. The second transport paddle includes a single paddle film, and transports the toner toward the developing unit 31 by rotating the film.

Further, by providing the rib 35 in the first storage chamber 321, when the previous paddle film hits the rib 35, the toner is blocked by the rib 35, and the toner is interposed between the rib 35 and the paddle film. A space without a gap is formed. 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 paddle film rotates, the toner also enters the space from above, so that there is no space inside the toner.
As the paddle film rotates in this state, the control valve 34 of the developing unit 31 is pressed against the paddle film of the first transport paddle 31d when the toner is pushed into the developing unit 31 side. Without overlapping the control valve 34 being opened, the toner is supplied from the toner cartridge 32 side to the developing unit 31 side through the communication port 33.
Next, the toner in the developing unit 31 enters the opened control valve 34. After that, the paddle film of the first transport 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 for the second transport paddle in the first storage chamber 321. A space is formed inside the toner by the film, and the toner is moved and discharged from the developing unit 31 side to the toner cartridge 32 side through the communication port 33 by overlapping when the space reaches the communication port 33.

The movement of the first, second and third transport paddles and the movement of the toner between the developing unit 31 and the toner cartridge 32 in the developing device 30 at this time will be described in more detail.
FIG. 5 is a diagram schematically illustrating toner movement between the developing unit and the toner cartridge. Here, the developing sleeve 31a and the like in the developing unit 31 are omitted.
In the developing device 30, as shown in FIG. 5 (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 in the toner cartridge 32 rotate a single paddle film. As shown in FIG. 5 (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. 5 (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 FIG. 5 (4) and FIG. 5 (5), the first transport paddle 31d has the control valve 34 returned to its 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.

Further, as shown in FIG. 5 (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 is in contact with the rib 35 in the second storage chamber 322 in the toner cartridge 32. When further rotated, as shown in FIG. 5 (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 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. 5 (8) and 5 (9), the first transport paddle 31d is moved back to the original angle when the plurality of paddle films are 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 is further moved and supplied from the toner cartridge 32 side through the communication port 33.
However, next, as shown in FIG. 5 (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. However, when there is a space formed inside the toner, the developing unit 31 extends laterally from the control valve 34 in the developing unit 31. Instead of returning to the inside, the toner moves from the developing unit 31 side to the toner cartridge 32 side through the communication port 33 and is discharged.

As shown in FIGS. 5 (11) and 5 (12), the paddle film of the first transport paddle 31 d 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, as shown in FIGS. 5 (13) to 5 (16), the first transport paddle 31d moves from the developing unit 31 side to the toner cartridge 32 side. It 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 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 in the toner cartridge 32, the number of times the space formed inside the toner contacts the communication port 33 can be reduced. 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 communication ports 33, and 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 dead space of toner in the developing unit 31.

FIG. 6 is a view showing a first transport paddle used in the one-component developing device according to the present invention. It is a perspective view of the 1st conveyance paddle used suitably for the present invention. The first conveyance paddle 31d has films 311 and 312 attached to a shaft having a quadrangular cross section, and two of the films extend in opposite directions on opposite surfaces. The opposing film 311 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 at the communication port 33 has a length that allows the convex portion of the film to be pushed in, and the concave portion 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, and the first conveying paddle 31d rotates, so that the toner is also transferred laterally by the convex portion of the film. A moving force is generated to cause horizontal agitation in the developing unit 31.

Further, by the rotation of the first transport paddle 31d, the convex portion of the film pushes the control valve 34 and returns the toner under the control valve 34 to the toner cartridge 32 side. This movement will be described later.
Since the first transport paddle 31d is set 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 when the toner cartridge has a 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 311 of the first transport paddle 31d, the control valves 34 are alternately pushed and released, that is, the adjacent control valves 34 are driven alternately to develop the inside of the developing unit 31. The movement of the toner is improved, and the circulation property with the toner in the toner cartridge 32 can be improved.

Here, the adoption of the paddle having the two comb-shaped films as described above improves the circulation and lateral agitation of the toner. However, with only the two sheets, the communication port 33 has a large amount of toner. The toner surface in the developing unit 31 undulates vertically and peaks and valleys are formed. If the communication port 33 is clogged, the supply of toner from the toner cartridge 32 is hindered, so that the amount of toner supplied to the entire developing unit 31 is reduced. Further, since toner flows from the toner cartridge 32 in the vicinity of the bottom of the toner peak, a phenomenon that uniformity of toner agitation is not ensured is observed. In order to improve this point, as a result of the examination, the interdigital film 311 and the interdigital film 311 are at an angle of 90 degrees between the two interdigital films and are shorter than the convex parts of the interdigital film. By adding a non-existing film, that is, a rectangular film 312 to the first conveyance paddle 31d, the toner pile at the communication port 33 was broken, and the toner surface in the developing unit 31 could be made almost horizontal.
As described above, by arranging the rectangular film 312 between the two comb-shaped films 311 in the first transport paddle, the amount of toner supplied from the toner cartridge 312 and the toner to the toner cartridge 32 are set. It is possible to achieve a sufficient circulatory action with a stable return amount. 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. If the control valve 34 is smaller than the communication port 33, the communication port 33 to which toner is supplied is blocked with 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 unit 31 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 unit 31 decreases.

  FIG. 7 is a front view showing a communication port portion provided in the developing unit. As shown in FIG. 7, the communication ports 33 are arranged so that the same number of the same shape in both the left and right directions is line symmetric with respect to the central portion in the longitudinal direction of the developing unit 31. By disposing each communication port 33 in this way, it is possible to more reliably ensure uniform flowability in a cross section perpendicular to the toner flow direction. Moreover, instead of making the control valves 34 at both ends in the longitudinal direction wider than the other control valves 34 by 20% or more, among the plurality of arranged control valves, the control valves 34 corresponding to the communication ports 33 at both ends. A control valve 34 having the same shape as the plurality of control valves 34 may be provided adjacent to the outside, that is, corresponding to a portion where the communication port 33 is not provided. By doing in this way, the control valve corresponding to the communication port 33 of both ends can be made into the same conditions as the thing with the same control valve 34 arrange | positioned on both sides like the other control valves 34. Therefore, it is possible to more reliably ensure the uniform flowability of the toner at each communication port 33 including the communication ports 33 at both ends.

FIG. 8 is a schematic diagram showing the configuration of the image forming apparatus 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 the 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 lower side of the main body of the image forming apparatus 1, 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 for moving the developing devices in the left-right direction in the drawing to perform the contact / separation operation with respect to the photosensitive belt 11 is further provided.

The toner in the developing device 30 is charged to a predetermined polarity, and a developing bias is applied to the developing sleeve 31 a by a developing bias power source, and the developing sleeve 31 a 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 to cancel the drive transmission, 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 developing position so that the leading edge of the Bk electrostatic latent image can be developed, the Bk developing sleeve 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 developing device of the corresponding color comes into contact with the photosensitive belt 11 in preparation for the development of the next color. 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 has a positional accuracy of 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, the developing device 30 will be further described in detail. The developing device 30 includes a developing sleeve 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 conveyance 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.
FIG. 9 is a schematic diagram showing the configuration of the communication port in the one-component developing device of the present invention. The communication ports 33 are arranged so that the same number of the same shapes in the left and right directions are line symmetric with respect to the central portion of the developing unit 31 in the longitudinal direction. By disposing each communication port 33 in this way, it is possible to more reliably ensure uniform flowability in a cross section perpendicular to the toner flow direction. Moreover, instead of making the control valves 34 at both ends in the longitudinal direction 20% or more wider than the other control valves 34, among the plurality of arranged control valves 34, control valves corresponding to the communication ports 33 at both ends. A control valve 34 having the same shape as that of the plurality of control valves 34 can be provided adjacent to 34 and outside thereof, that is, corresponding to a portion where the communication port 33 is not provided. By doing in this way, the control valve 34 corresponding to the communication port 33 of both ends can be made into the same conditions as the thing with the same control valve 34 arrange | positioned on both sides like the other control valves 34. Therefore, it is possible to more reliably ensure the uniform flowability of the toner in each communication port 33 including the communication ports 33 at both ends.

There are a plurality of communication ports 33 on the developing unit 31 side, and a slide shutter with an elastic member attached is provided between the developing unit 31 and the toner cartridge 32. By moving the slide shutter, the communication port 33 provided in the housing of the developing unit 31 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 main body of the image forming apparatus, the communication port 33 is closed in order to prevent the toner from spilling out from the toner cartridge 32. Provide a slide shutter. An elastic member, a slide shutter, and a fixed seal are provided for the toner cartridge 32. The elastic member is preferably a foamed material such as urethane resin or silicone resin.
As shown in FIG. 9, a window portion opened to the slide shutter 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 portion of the slide shutter, and when the communication port 33 is opened, the slide shutter is moved so that the window portion and the communication port 33 are aligned with each other. To communicate.

In the image forming apparatus 1, the developing device 30 transports the toner to the developer supply roller 31b while stirring the toner with the first transport paddle 31d in the developing unit 31, and the supply roller 31b rubs against the developing sleeve 31a. At the same time, the toner is rubbed and frictionally charged to charge the toner. The charged toner is attracted to the developing sleeve 31a with a mirror image force and conveyed. Thereafter, the amount of toner conveyed to the developing area is regulated by the doctor roller 31c. A thin toner layer formed on the developing sleeve 31a is developed on the photosensitive belt with a developing bias in the developing region.
At this time, the toner rubbed against the developing sleeve 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.
As described above, the deteriorated toner increases in the developing unit 31, 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 main body of the toner cartridge 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 into 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, and then to the first storage chamber 321 by the third transport paddle. Returned. 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 sleeve 31a and developing the toner with the toner that has approached the original state and the unused toner.

Next, the driving of the doctor roller will be described.
The shaft of the doctor roller 31c and the rotor of the stepping motor are directly connected, and a pulse is input to the stepping motor to change the contact position between the doctor roller 31c and the developing sleeve 31a. A part for detecting the position is provided on a part of the core of the doctor roller 31c to detect the current contact position. A driving force from a motor such as a stepping motor is connected to the axis of the doctor roller 31c via a gear transmission system (planetary gear, worm gear, wheel gear, etc.) with a high reduction ratio, and the motor is detected while detecting the position of the doctor roller 31c. Is driven / stopped to change to a specific contact position between the doctor roller 31c and the developing sleeve 31a.
As the means for detecting the position of the doctor roller 31c, the following means can be provided. A reflector having approximately the same size as the nip width is provided on the doctor roller 31c for optical detection. A magnetic recording means having approximately the same size as the nip width is provided on the doctor roller 31c for magnetic detection. Further, the doctor roller 31c There are means such as detecting the position with an encoder that is directly connected, and any of them is appropriately selected and used.
Further, as an example of the size of the doctor roller 31c and the form of division of the use surface, for example, if the outer diameter of the doctor roller 31c is φ14.5, the outer periphery is 45.5 mm, and the nip width between the doctor roller 31c and the developing sleeve 31a is If it is 0.5 mm, the outer peripheral surface can be divided into 90 parts. If 2000 sheets can be printed at one place, 180,000 sheets can be printed by the doctor roller 31c.

Next, the operation of the doctor roller will be described.
A toner layer is formed on the surface of the developing sleeve 31a by contacting the developing sleeve 31a at a position on the surface of the doctor roller 31c. As an example, after developing 50 sheets corresponding to the A4 width, the doctor roller 31c is rotated so as to be another contact surface on the surface of the doctor roller 31c. Since the rotation angle is divided into 90 along the above example, it is set to 4 °. If it rotates 360 °, of course, it contacts the developing sleeve 31a at the same position. The positions for each division of the doctor roller 31c are n1, n2,..., N90, and the number of sheets used at each position is stored in the storage means. The storage means may be installed in the developing unit, or may be built in the control unit of the main body. Therefore, in this example, 50 sheets are counted up for each position. Here, n1, n2,..., N90, (return to n1) are used in order, and when each counts 2000, a total of 180,000 sheets are printed. If the specification of the developing unit 31 is less than that, for example, 150,000 sheets of life (about 1700 counts at each position of the doctor roller 31c), the doctor roller 31c is still in a sufficiently usable state. Can maintain stable image quality. In this state, the development unit 31 has at least 30,000 sheets, so if you continue to use it without forced replacement, the cost per sheet can be reduced and the user's merit will come out. Take a method to notify only such messages periodically. By doing in this way, since the surface of the doctor roller 31c can be uniformly worn, the image quality does not change regardless of the position.
In the usage method in which the position cannot be specified so far, the wear of only a certain place has occurred, and the rotation of the doctor stops at that position, and further wear of that position has been promoted. In such a situation, the wear on the surface of the doctor roller 31c is particularly advanced, and when it comes to that position, uneven stripes are likely to occur, and the state of the toner layer (charge amount, charge distribution) is also used in another place. Since the surface state of the doctor roller 31c changes depending on the location, the image quality has changed.

Next, a case where a replaceable toner cartridge 32 is mounted will be described.
The toner cartridge 32 is filled with a necessary amount of toner, and is replaced with a new toner cartridge 32 when the remaining amount of the toner becomes low. As an example, if the amount of toner to be used is 450 g and the target toner amount is 450 g (50 g left in the toner cartridge 32), and an A4 5% image consumes an average of 0.018 g, this toner cartridge 32 has 25,000 sheets (5 % Image) can be printed. As described in the problem section, as the toner in the toner cartridge 32 is used and consumed, the toner in the toner cartridge 32 and the toner in the developing unit 31 are reduced in the amount of additives on the toner surface, and the toner cohesiveness is increased. The characteristics change such that the ratio of toner particles having a large particle size increases, the charging ability of the toner decreases, and the like. Accordingly, the wear speed of the surface of the doctor roller 31c increases.
FIG. 10 is a graph showing the amount of external additive on the toner surface, the ratio of the large particle toner, and the amount of wear on the doctor roller surface with respect to the amount of toner used in the toner cartridge. FIG. 10-1 shows a decrease in the amount of external additive (silica, titanium, etc.) on the surface of the toner of the developing unit 31 (here, the toner near the doctor roller 31c) with respect to the amount of toner used in the toner cartridge 32. It shows a state. In most of the range, a linear decrease with a gentle gradient is observed. This is because toner with little deterioration is supplied from the toner cartridge 32, and the transfer of the additive from the supplied toner to the toner of the developing unit 31 occurs. For this reason, there is toner circulation between the toner cartridge 32 and the developing unit 31, and the deteriorated toner in the developing unit 31 is returned to the toner cartridge 32 and the additive is supplied by the fresh toner abundant in the toner cartridge 32. is there. In this range, since the additive is still sufficiently present on the surface, the degree of aggregation of the toner has not increased so much.

Next, FIG. 10-2 shows a change in the ratio of the large particle size toner with respect to the toner in the developing unit 31.
In the developing method using powder toner, since the toner has original particle size variation (particle size distribution), a relatively small one tends to be consumed first. (Although it is not perfect selectivity, because of such a tendency, the decrease in the small particle size toner is fast and the decrease in the large particle size is slow.) Therefore, the average particle diameter increases and the ratio of toner having a large particle diameter increases. When the toner amount of the developing unit 31 starts to decrease in accordance with the consumption of the toner in the toner cartridge 32, the ratio of the large particle size toner increases toward the end (because the denominator becomes small), and the doctor roller increases accordingly. The probability that such large-diameter toner enters 31c and developing sleeve 31a increases. Such toner is difficult to pass through the doctor nip and is difficult to return to the developing unit 31 from the nip portion, so that the toner tends to stay in the nip portion, and the doctor roller 31c is easily worn there.
As described above, the increase in the toner cohesion and the increase in the ratio of the large particle size toner act synergistically when the toner usage amount of the toner cartridge 32 approaches the upper limit of use, and the wear speed of the doctor roller 31c. As shown in FIG. 10-3, the amount rapidly increases near the upper limit of use with respect to the amount of use of cartridge toner.
Therefore, in order to make the wear of the doctor roller 31c uniform at each position on the entire circumference, the number of used toner cartridges 32 is stored, and when the used number exceeds a specified value, the operation of moving the position of the doctor roller 31c is performed. If the number of sheets is smaller than a predetermined number (in the above description, the movement has been performed every 50 sheets), for example, every 20 sheets, the curve of the amount of wear increases rapidly in the last direction. Let it be done on a sheet-by-sheet basis.
However, since the degree of toner deterioration accurately corresponds to the usage amount of the toner cartridge 32, when the majority of output images such as standard documents have an image area ratio within a certain range, the above control is switched depending on the number of used sheets. Good.
However, if the image area ratio to be output is greatly deviated from the average, there is a discrepancy between the amount of toner used and the number of toner used, and it is necessary to cope with this.
At present, it is actually difficult to monitor the amount of toner remaining in the toner cartridge 32 in a state where it is installed in the apparatus, and there is no such implementation. Here, the number of used sheets and the image area ratio of the output image (pixel count can be substituted) are stored in the storage means, and the toner usage amount of the toner cartridge 32 is calculated therefrom. By adjusting the timing at which the movement is performed, an image with any area ratio can be handled.

  In the explanation of the wear of the doctor roller 31c, it was described that the toner stays in the doctor nip portion. In order to reduce the wear rate, it is effective to move the toner in the doctor nip portion to the developing unit 31 side as much as possible to prevent stagnation. In that case, when changing the contact position of the doctor roller 31c, the rotation angle is made larger than usual, and the staying toner is carried on the doctor roller 31c and scraped off by a scraper in contact with the doctor roller 31c. In the series of examples described so far, the step angle is set to 4 °. However, when the number of used toner cartridges 32 exceeds a specified value, the step angle is moved by an integral multiple thereof, for example, 24 °. The deteriorated toner that promotes wear from the nip portion is moved away from the nip so as not to be caught again, and is transported to the scraper portion with a small number of movements. Since the number of sheets used at each position on the surface of the doctor roller 31c is stored in the storage means, the next contact position is adjusted while adjusting so that a position with a large number of sheets is not selected as the next contact position. Set the rotation angle movement amount to decide.

Subsequently, an operation example regarding the image area ratio will be described.
If low image area continues to be taken, toner degradation will progress and the last rise in the wear curve described above will be accelerated. Therefore, it is necessary to shorten the number of printed sheets (cycle) for moving the doctor roller 31c. Further, since the amount of wear of the toner cartridge 32 starts to increase earlier, it is necessary to start shortening the operation cycle when the number of used toner cartridges 32 is similarly small. The low image area ratio and the degree of deterioration of the toner depend on the method and system used, but the toner particle size, the amount of additive, and the chargeability are measured. The degree of deterioration increases as the area ratio decreases at an image area ratio below that. Usually, in the case of average use by a wide range of users, the image area ratio is about 4 to 5%. When the average image area is smaller than that, for example, when the image is used with a 1% image, the degree of deterioration of the toner cartridge 32 at the final stage is considerably increased. One of the causes is that the actual operation of the developing unit 31 is 4 to 5 times as much as that in normal use under such use conditions.

If the working time of the developing unit 31 is excessively extended with respect to the consumption life of the toner cartridge 32, this causes a problem. Therefore, when an extremely low image is used, the toner deteriorates and the developing unit In order not to prolong the actual working time 31, toner is consumed to some extent to prevent problems. For example, with an image area of 3% as a reference, when an image of 3% or less is printed, the toner is consumed except for during the developing operation when the image is less than 3%. Under the condition of 3% or more, such consumption is not performed, and the toner consumption rate is set to the image area.
However, even in this case, as described above, there is a difference in the degree of deterioration of the toner between 3% and 10%, and the wear curve also slightly changes.
Therefore, by examining the toner deterioration and the wear state in increments of 1% between 3% and 10%, and controlling the movement cycle of the doctor roller 31c so that the wear amount can be adjusted, the variation in the wear of the doctor roller 31c depending on the image area can be reduced. It can be corrected.
Furthermore, when the usage pattern is intermittent, such as output for every single sheet or output for every two sheets, or when used continuously, such as repeat copying in copying or continuous printing on a printer. Therefore, even if the same number of sheets is used, there is a difference in the amount of wear on the surface of the doctor roller 31c.
That is, when continuous printing is performed, the surface temperature of the rotating member such as the developing sleeve 31a is increased due to the generation of frictional heat, and accordingly the contact position of the doctor roller 31c is also increased due to friction and heat conduction, resulting in wear. To progress.
Therefore, in the case of continuous use, it is necessary to perform the movement operation of the doctor roller 31c with a smaller number than usual in order to keep the wear amount at the same level.

Here, as an example, if the average P / J (print per job) is 5 or less, the movement operation is executed every 50 predetermined sheets.
If the average is 10 P / J or less, the moving operation is executed when 40 sheets are exceeded, and if the average is 15 P / J or less, the moving operation is executed when 30 sheets are exceeded. By doing so, it is possible to suppress the promotion of wear at one place.
However, there are cases where the predetermined number of moving cycles is inevitably exceeded, such as continuous use of 50 P / J or more, or when 30 sheets are used continuously after repeating 10 P / J three times. Since the time required for the movement of the doctor roller 31c does not take much, it is possible to interrupt the developing operation. During the fall time after the development drive is stopped, the doctor roller 31c is moved, and after that, the development sleeve 31a is started in about 2 to 3 seconds at the most during the rise time until the development drive is actually started. It is possible to stabilize the toner layer.
However, there is a case where the user feels resistance to stopping the print job. In this case, the use of the doctor roller 31c is continued at the same position without stopping, but the wear amount at the position is slightly advanced from the other positions. Therefore, the wear amount is adjusted by skipping the next use timing based on information such as the number of used sheets, continuous use conditions, number of used toner cartridges 32, and average image area ratio.

As for wear, the temperature rise was taken up during continuous printing, but it is also affected by the surrounding environment.
When the ambient temperature is high, the temperature at which the wear of the doctor roller 31c is promoted is reached in a short time. On the other hand, when the ambient temperature is low, heat is released and it takes time to reach the temperature. Therefore, even if it is about 5 P / J, it may be necessary to change the contact position of the doctor roller 31 c in a short cycle. Similarly, as an influence of humidity, there is a case where the degree of toner aggregation increases in a high humidity environment, thereby promoting the wear of the doctor roller 31c. That is, it is necessary to monitor the ambient temperature and humidity and thereby adjust the number of operations for changing the contact position of the doctor roller 31c. As a specific example, when the ambient temperature exceeds 30 ° C. and the ambient humidity exceeds 70%, the normal movement of the doctor roller 31c is performed every 50 sheets, whereas it is performed every 40 sheets. Change the setting as follows. Further, when an increase in the amount of wear can be predicted from information such as the continuous use condition, the number of toner cartridges 32 used, and the average image area ratio, the set number of operation cycles for changing the contact position of the doctor roller 31c is reduced. By controlling 31c to wear in the same way around the entire circumference, it is possible to prevent uneven wear and local wear from occurring.

  Although the specific configuration of the doctor roller 31c has conventionally been an example of a metal roller (SUS, etc.), the doctor roller 31c is deformed to some extent on its surface in order to make the contact pressure uniform in the axial direction with the developing sleeve 31a. It is preferable to form a nip. Here, a core layer with a rubber layer (urethane rubber, EPDM, NBR, silicon rubber, etc.), and a surface coated with a resin material that can easily impart charge to toner (nylon) System, urethane resin), and also made of fluoro rubber to prevent toner sticking to the surface of the doctor roller 31c, and using fluoro resin (ETFE, Lumiflon: Asahi Glass) as coating material Take as an example. As a surface material, a hard material is excellent in wear, but in general, a problem of toner fixation is likely to occur. On the other hand, fluororesin and rubber materials that are hard to stick with low surface energy, on the other hand, have a surface that is easy to wear. . One of the methods for extending the service life is to take a certain amount of wear into account (when it is used while being worn, it becomes difficult to fix). Accordingly, it can be said that the form in which the doctor roller 31c advantageous for fixing is used in the usage method of the present invention is the method that extends the life and causes little deterioration in image quality.

Furthermore, it is desirable to make the contact pressure uniform so as to prevent uneven wear in the axial direction. For this reason, the shape of the doctor roller 31c in the axial direction is not a pure cylinder but a barrel shape in which the central part is slightly thicker. The curve is preferably a quadratic curve or a quartic curve. This is because when the doctor roller 31c is brought into contact with the developing sleeve 31a with a predetermined pressure, the doctor roller 31c is deflected in the axial direction, but the contact pressure can be adjusted. This is a desirable combination so that the doctor roller 31c having such a shape is used in the method of use of the present invention, long life, and image quality is not deteriorated.
The supply roller 31b is formed by forming a layer of foamed urethane or the like on a metal core, but rotates so as to move in a direction opposite to the moving direction of the developing sleeve 31a at the contact position with the developing sleeve 31a. And a method of rotating the developing sleeve 31a so as to move in the same direction as the moving direction of the developing sleeve 31a can be selected. In the former, excess toner is peeled off from the developing sleeve 31a and a toner layer is formed with the supplied toner (has a refreshing effect), so that afterimage prevention and charging stability are good, but the developing sleeve 31a. The life of the supply roller 31b and the life of the rotary bearing that supports the rotation are shortened, and it is difficult to extend the life of the entire unit. In the latter case, the lifetime of the component parts of the unit can be ensured, and since there is no refreshing action, the same toner may remain on the developing sleeve 31a and may be stressed there. However, in the combination of the present invention, the nip portion of the doctor roller 31c If the return action from the toner to the developing unit 31 is utilized, the overall life can be extended.

  The developing device 30 can be a process cartridge that is integrally supported together with the drum-shaped photoconductor 11 and is detachably formed on the main body of the image forming apparatus 1. In addition, the process cartridge may include a charging unit and a cleaning unit.

1 is a schematic diagram illustrating a configuration of a one-component developing device according to the present invention. FIG. 3 is a schematic diagram illustrating a structure of a control valve disposed in a developing unit in the one-component developing device of the present invention. FIG. 6 is a diagram for schematically explaining a state in which toner is supplied from a toner cartridge side to a developing unit. FIG. 6 is a diagram for schematically illustrating a state in which toner is returned from a developing unit side to a toner cartridge. FIG. 5 is a diagram schematically illustrating toner movement between a developing unit and a toner cartridge. FIG. 5 is a diagram schematically illustrating toner movement between a developing unit and a toner cartridge. FIG. 5 is a diagram schematically illustrating toner movement between a developing unit and a toner cartridge. FIG. 4 is a diagram illustrating a first transport paddle used in the one-component developing device according to the present invention. FIG. 6 is a front view showing a communication port portion provided in the developing unit. 1 is a schematic diagram illustrating a configuration of an image forming apparatus of the present invention. FIG. 2 is a schematic diagram illustrating a configuration of a communication port in the one-component developing device of the present invention. 5 is a graph showing the amount of external additive on the toner surface, the ratio of large particle toner, and the amount of wear on the surface of the doctor roller with respect to the amount of toner used in the toner cartridge.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Photoconductor unit 11 Photoconductor belt 12 Photoconductor cleaning apparatus 13 Charging roller 14 Drive roller (photoconductor)
15, 16 Followed roller (photosensitive member)
20 Writing Optical Unit 21 Semiconductor Laser 22 Polygon Mirror 23 Reflecting Mirror 25 Feeding Roller 26 Contacting / Separating Mechanism 30 Developing Device 31 Developing Unit 31a Developing Sleeve 31b Supply Roller 31c Doctor Roller 31d First Conveying Paddle 31e Slide Shutter 31f Elastic Member 31g Window Portion 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 section 34b Film 34c Wide film (wide control) valve)
34d Film not compatible with communication port (control valve not compatible with communication port)
35 Rib 40 Intermediate transfer unit 41 Intermediate transfer belt 42 Belt cleaning device 43 Mark sensor 44 Drive roller (intermediate transfer belt)
45 Primary transfer rollers 46, 47, 48 Driven roller 49 Waste toner tank 50 Secondary transfer unit 51 Secondary transfer roller 60 Fixing unit 61 Fixing belt 62 Pressure roller 65 Duplex switching claw 70 Duplex printing paper reversing unit 71 Reverse switching claw 72 Reverse roller 80 Paper feed device 81 Paper feed roller 82 Registration roller 83 Manual feed tray 84 Paper discharge tray 90 Transfer material

Claims (13)

A toner carrier for visualizing the electrostatic latent image by attaching a one-component toner to the image carrier on which the electrostatic latent image is formed;
A toner supply rotator that rotates in contact with the toner carrier and supplies toner to the toner carrier;
Toner conveying means for feeding toner to the toner supply rotating body;
In a one-component developing device comprising: a cylindrical adhesion amount regulating member that contacts the toner carrier to regulate the amount of toner applied to the toner carrier from the toner supply rotating body;
The one-component developing device is
Means for detecting the position of the adhesion amount regulating member and means for storing the number of sheets used at the detected contact position;
The one-component developing device, wherein the contact position of the adhesion amount regulating member is changed when a predetermined number of sheets are used at the detected contact position. The one-component developing device has a toner cartridge for storing a detachable replenishing toner, and can be replaced with a new toner cartridge after using the mounted toner cartridge,
It has means for storing the number of used cartridges, and when the number of used toner cartridges exceeds a predetermined value, the operation of changing the contact position with a smaller number of used sheets is performed. The one-component developing device according to claim 1. The one-component developing device has means for storing the number of used cartridges, and lengthens the operating distance for changing the contact position when the number of used toner cartridges exceeds a predetermined value. The one-component developing device according to claim 1, wherein: The one-component developing device has means for detecting and storing the image area ratio of the output image,
4. The one-component developing device according to claim 1, wherein when the image area ratio is equal to or less than a predetermined value, the operation of changing the contact position is performed with a smaller number of sheets used than the predetermined number. . The one-component developing device has means for detecting and storing the continuous number of sheets when performing a continuous printing operation,
5. The one-component developing device according to claim 1, wherein when the continuous number is equal to or greater than a predetermined value, the operation of changing the contact position is performed with a smaller number than the predetermined number. The one-component developing device has means for detecting and storing the ambient temperature,
6. The one-component developing device according to claim 1, wherein when the detected temperature is equal to or higher than a predetermined value, the operation of changing the contact position is performed with a smaller number of sheets used than the predetermined number. The one-component developing device has means for detecting and storing ambient temperature and humidity,
7. The one-component developing device according to claim 1, wherein when the detected humidity is equal to or higher than a predetermined value, an operation of changing the contact position with a smaller number of sheets used than the predetermined number is performed. The one-component developing device according to any one of claims 1 to 7, wherein the adhesion amount regulating member includes a core metal covered with a rubber layer or a rubber layer and a resin coat layer thereon. The one-component developing device according to claim 8, wherein the outermost layer of the adhesion amount regulating member includes fluororubber or fluororesin. 10. The one-component developing device according to claim 8, wherein a shape of the adhesion amount regulating member is a quadratic curve or a quartic curve with respect to an axis. 11. The toner supply rotating body according to claim 1, wherein a rotation direction of the toner supply rotating body is the same as a rotation direction of the toner carrying body at a position where the toner supply rotating body is in contact with the toner carrying body. The one-component developing device described. At least in the process cartridge that integrally supports the image carrier and the developing device and is detachable from the image forming apparatus main body,
A process cartridge using the one-component developing device according to claim 1. An image carrier that carries a latent image, a charging device that uniformly charges the surface of the image carrier, an exposure device that writes an electrostatic latent image on the surface of the charged image carrier, and a surface formed on the surface of the image carrier. A developing device that visualizes the electrostatic latent image, a transfer device that transfers the visible image on the surface of the image carrier directly or via an intermediate transfer member, and a toner on the image carrier. In an image forming apparatus comprising a cleaning device for performing a fixing and a fixing device for fixing a visible image on a recording member with heat and / or pressure,
The image forming apparatus according to claim 1, wherein the image forming apparatus uses a one-component developing device according to claim 1.

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