JP2008107442A - One-component developing device, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device preventing toner supplied from a toner cartridge from flowing back before agitated to the toner cartridge and sufficiently agitating, the toner existing in a hopper and the toner supplied from the toner cartridge to obtain the same toner charging characteristics and eliminate, instable charging, thereby preventing the problems resulting from toner deterioration. <P>SOLUTION: The developing device 30 includes: a developing unit 31 for developing an electrostatic latent image with the one-component toner; a toner cartridge 32 having a path through which the toner passes horizontally between the developing unit 31 and the toner cartridge 32; a control valve 34 disposed in the developing unit and for controlling the supply/discharge of the toner between the developing unit 31 and the toner cartridge 32; and a mechanism disposed in the toner cartridge 32 and for periodically forming a cavity near the path, wherein a first rotary agitating member 343 is disposed under the control valve 34. <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 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 many cases, it has been put into 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 carrier are sufficiently stirred and mixed in the developing device and then transported to a 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 / 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 roller, the toner is thinned by the layer thickness regulating member and developed, and 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 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. .

  For example, Patent Document 1 proposes a developing device in which a back valve is provided at the communication port 34 to prevent back flow to the cartridge side. In the configuration of this prior art, the toner of the developing unit cannot return to the toner cartridge side, so that there is a problem that the developing unit is clogged with toner and voids are eliminated. As a result, the toner in the hopper is insufficiently agitated, and the chargeability of the toner is deteriorated, resulting in background contamination, density unevenness, and toner dropping. Further, since the toner in the hopper is unilaterally fatigued, the difference in chargeability between the toner in the cartridge and the toner supplied from the cartridge is not well stirred and sent to the developing unit. The toner in the hopper was reversely charged or lowly charged, causing scumming or blurring.

JP 2002-162817 A

  However, in the conventional technology, the toner supplied from the cartridge is returned to the cartridge side by the control valve before being mixed with the toner in the hopper in the developing unit and stirred. As a result, the supply of new toner to the hopper is hindered, and the efficiency of returning deteriorated toner to the cartridge is reduced. The toner supplied from the cartridge to the hopper is agitated with the toner originally contained in the hopper by the rotating agitating member driving the control valve, and is conveyed to the developing roller side. Therefore, before being sufficiently stirred, it is supplied to the developing roller. As a result, a new highly chargeable toner and a toner with reduced chargeability in the vicinity of the developing roller are mixed, and the two types of toner are frictionally charged on the developing roller, thereby generating reversely charged toner and preventing charging. There is a problem that the image quality is deteriorated, such as stabilization and a decrease in resolution of the occurrence of background contamination. In addition, due to the insufficient stirring, toner recovery around the developing roller is delayed, fluidity is lowered, and it becomes more difficult to replace the toner, so that toner deterioration (addition of additives and increase in cohesion) proceeds. End up. As a result, toner agglomerates are formed, white streaks are generated, toner adheres to the developing roller, filming (film-like adhering), and unevenness and torque increase due to toner adhering to the entrance seal and end seal. .

  Therefore, the present invention has been made in view of the above problems, and the problem is that the toner supplied from the toner cartridge is prevented from flowing back to the toner cartridge before being agitated, and was originally in the hopper. Provided is a developing device in which toner and toner supplied from a toner cartridge are sufficiently agitated to match the chargeability of the toner, to solve the above-described unstable charging, and to prevent problems caused by toner deterioration. That is.

The features of the present invention, which is a means for solving the above problems, are listed below.
The developing device according to the present invention includes a developing unit that develops a one-component toner on an electrostatic latent image on an image carrier, and is detachable from the developing unit. When the developing unit is attached to the developing unit, A toner cartridge having a passage through which toner can pass in a direction, and a control valve for controlling supply / discharge of toner between the developing unit and the toner cartridge is provided inside the developing unit, and the toner cartridge is regularly near the passage. In the developing device having a mechanism for forming a space in the first rotary stirring member, a first rotating stirring member is provided below the control valve.
The developing device of the present invention is further characterized in that the first rotating stirring member has an acting force for conveying the toner to be stirred in the axial direction of the first rotating stirring member.
In addition, the developing device of the present invention further includes a second rotating stirring member that conveys toner from the first rotating stirring member to the developing roller.
The developing device of the present invention is further characterized in that the second rotary stirring member also serves as a drive mechanism that provides a drive force for driving the control valve.
The developing device of the present invention is further characterized in that the control valve and its driving mechanism are provided above the toner surface in the developing unit.
The developing device of the present invention is further characterized in that the first rotating stirring member has a higher rotational speed than the second rotating stirring member.
The developing device of the present invention is further characterized in that the rotation frequency of the first rotating stirring member is higher than the driving frequency of the control valve.
The developing device of the present invention is further characterized in that the drive frequency of the control valve is synchronized with the rotation of the second rotating stirring member.
The developing device of the present invention is further characterized by using a toner having a bulk density in the range of 0.4 to 0.6 g / cm ³ and a glass transition point in the range of 60 to 90 ° C. .

The process cartridge of the present invention is characterized in that at least the image carrier and the developing device are integrally supported, and the above-described developing device is used in the process cartridge that is detachable from the main body of the image forming apparatus. .
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 for cleaning toner on a body and a fixing device for fixing a visible image on a recording member with heat and / or pressure, wherein the developing device described above is used. To do.

As described above, in the developing device of the present invention, before the toner supplied from the cartridge is immediately conveyed to the developing roller side, the toner in the hopper is made to be charged by stirring well with the toner in the hopper. The promotion of deterioration can be suppressed, problems caused by toner deterioration such as background stains and white stripes can be prevented, and stable image quality can be obtained over a long period of time.
Furthermore, by supplying a sufficiently agitated toner to the developing roller uniformly and stably, the toner and toner aggregate with increased aggregation do not stay around the developing roller, and white streaks are generated and the developing roller filming occurs. And stable image quality can be obtained over a long period of time. Furthermore, in the case of a color toner having a toner bulk density in the range of 0.4 to 0.6 g / cm ³ and a glass transition point in the range of 60 ° C. to 70 ° C. By using the toner in the circulation type developing device of this configuration, the stirring operation can be efficiently performed, the toner deterioration with time can be delayed, and the image quality can be stabilized for a long time.

  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 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 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 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, Y, C, and M 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 Y, C, and M). 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 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. FIG. 2 is a schematic diagram showing a configuration in the vicinity of the developing device of the present invention.
The developing device 30 is arranged in four colors in the order of K (black) Y (yellow) C (cyan) M (magenta) from the top on the left side of the main body (image forming order is KYCM). Open the cover. The toner cartridge 32 is set in the developing device 30 and is taken out when the developing unit 31 is taken out. In the normal toner replacement, the front cover of the main body is opened and the door is further opened, and only the toner cartridge 31 is replaced. Further, an ID chip 32f is attached to the toner cartridge 31, and information on the toner cartridge 31 is stored, which is used for toner remaining amount detection and new article detection.
The developing device 30 includes a developing roller 31a that rotates while carrying toner on the surface in order to develop an electrostatic latent image on the surface of the photoreceptor belt 11, and a toner conveyance paddle 31d that rotates to pump up and stir the toner. The developing unit 31 includes a toner cartridge 32 that stores 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. The developing unit 31 includes a developing roller 31a, a toner supply roller 31b, and a doctor roller 31c. Further, paddles 31d, 32a and 32b (in the description: also described as agitators) for stirring and replenishing toner are provided in the toner cartridge 32 and the developing unit 31, respectively.

FIG. 3 is a perspective view showing the configuration of the developing device of the present invention.
The drive of the gear of the developing unit 31 is transmitted from the developing roller 31a, and the transport paddles 32a and 32b of the two agitators are rotated in one direction by the one-way clutch. In the configuration of the present invention, a single blade (mylar) configuration is suitable for the transport paddle 31d which is an agitator on the developing unit 31 side. In this mylar, stirring and replenishment and a toner replenishment passage of the toner cartridge 32 are used. A space is formed in the vicinity of a certain communication path 33.
Further, the toner cartridge 31 is provided with a shutter mechanism. When the toner cartridge 31 is inserted into the developing unit 31, the shutter is automatically opened. Only the toner bottle for the start uses a toner bottle with a strong toner replenishment power. This is because when a new developing unit 31 is set up, a large amount of toner needs to be supplied to the empty toner hopper 31h in a short time.
As a developing mechanism, the toner replenished in the developing unit 31 is agitated by the agitator 31d in the developing unit 31, transported to the replenishing roller 31b, and further transported from the replenishing roller 31b to the developing roller 31a. . The amount of toner adhering to the developing roller 31a is regulated by the doctor roller 31c, and development is performed in contact with the photoreceptor belt 11. The doctor roller 31c is attached with a one-way clutch and does not normally rotate. However, when the developing roller 31a reverses after completion of the job, the doctor roller 31c rotates in the same direction so that toner is accumulated between the doctor roller 31c and the developing roller 31a. It is preventing.

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. 4 is a diagram schematically illustrating 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. 4A, the control valve 34 in the developing unit 31 is attached to the support and has a certain angle. The 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. 4B, in the developing unit 31, a plurality of paddle films push the control valve 34 in the transport paddle 31d. At this time, the toner between the control valve 34 and the communication port 33 is Since the toner cartridge 32 side is also filled with toner, the communication port 33 cannot be moved, and returns to the developing unit 31 from the control valve 34 in the developing unit 31 in the lateral direction. Next, as shown in FIG. 4 (3), in the transport paddle 31 d, a 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. Next, as shown in FIGS. 4 (4) and 4 (5), the transport paddle 31d is moved back to the original angle when the plurality of paddle films are separated from the control valve 34. A large gap is formed and a space is formed, so that the toner moves from the toner cartridge 32 side through the communication port 33 and is supplied.

Furthermore, as shown in FIG. 4 (6), the paddle film of the 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. 4 (7), the paddle film of the 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. 4 (8) and 4 (9), the transport paddle 31d is moved back to the original angle when the plurality of paddle films are separated from the control valve 34. 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. 4 (10), the paddle film of the 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. 4 (11) and 4 (12), the paddle film of the transport paddle 31d further moves from the developing unit 31 side to the toner cartridge 32 side by pushing the control valve 34 again. Discharged.
Further, by making the rotational speed of the transport paddle 31d faster than the transport paddles 32a and 32b, the transport paddle 31d moves from the developing unit 31 side to the toner cartridge 32 side as shown in FIGS. Can be made.
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 transport paddle 31d in the developing unit 31 and the transport paddles 32a and 32b 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 transport paddle 31d in the developing unit 31 faster than the transport paddles 32a and 32b 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 conveyance paddle 31d pushes the control valve 34, the number of times of supplying 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 transport paddle 31d is provided for every other comb tooth shape corresponding to the comb-like control valve 34, and it is provided for every control valve 34 with two paddle films. Thus, the control valves 34 can be operated alternately. By alternately operating, the toner can be discharged evenly without forming a dead space of toner in the developing unit 31.

At this time, the operation of the control valve 34 in the developing hopper 31f in which toner exists in the developing unit 31 will be described. The control valve 34 has an effect of increasing the supply force. The toner is pulled to the hopper side by the pump effect when the valve is repelled by the paddle of the developing unit 31 and the valve returns at a stroke. On the other hand, when there is a space where there is no toner in the communication port 34 on the toner cartridge 32 side, it functions to return the toner to the toner cartridge 32. Further, the transport paddles 32a and 32b in the toner cartridge 32 have an effect of increasing the return force. In order to carry the toner, it is necessary to create a space where the toner is to be taken. A space is formed in front of the supply path of the toner cartridge 32, and the toner on the developing hopper 31h side is pushed out by the control valve 34. A return operation is achieved. In the case of the two-paddle, even if the toner in front of the communication port 34 is applied with one paddle, the other paddle immediately sends the toner to the front of the communication port 34, and a necessary space cannot be secured for a predetermined time. Therefore, it is possible to prevent the toner from being sent in front of the communication port 34 by using only one paddle on one side.
Further, the rib 35 in the toner cartridge 32 has an effect of helping to create a space and further increasing the return force. Only the transport paddles 32 a and 32 b have a weak force for creating a space in front of the communication port 34. Therefore, by attaching the rib 25, the toner is prevented from flowing in front of the communication port 34.

FIG. 5 is a schematic view showing a transport paddle used in the developing unit in the developing device according to the present invention. The transport paddle 31d of the first rotary transport member transports toner to the developing roller 31a. The transport paddle 31d has a flat plate (blade) attached to a shaft having a quadrangular cross section, and two of them extend in opposite directions on opposite surfaces. The opposing flat plate has a concavo-convex shape (comb shape), but the two convex portions are configured to be displaced. The uneven portion corresponds to the position of the communication port 33 of the developing hopper 31h. The control valve 34 provided in the communication port 33 is long enough to be pushed by the flat plate convex portion, and the concave portion does not contact the control valve 34. Shape. Further, the base part of the convex part of the flat plate is made wider (C-shaped) than the tip part, and the toner is generated at the shaded part of the flat convex part by rotating the transport paddle 31d in the developing unit 31. Is generated in the horizontal direction, and the toner in the developing hopper 31h is agitated in the horizontal direction.
Further, in the developing device 30 in which the transport paddle 31d is provided and the control valve 34 is pushed in, it is desirable that the transport paddle 31d is maintained at a necessary distance from the control valve 34 and is not in contact therewith.
Further, the rotation of the transport paddle 31d of the developing hopper 31h causes the flat projection to push the control valve 34 and return the toner below the control valve 34 to the toner cartridge 32 side.
As shown in Table 1, the transport paddle 31d (66 rpm) of the developing hopper 31h is set to rotate considerably faster than the transport paddles 32a and 32b (8 rpm) of the toner cartridge 32. The control valve 34 could be operated several times by the hopper paddle 31d within the time allowed, and the toner could be efficiently returned to the toner cartridge 32. When the flat plate convex portion 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 hopper side and the toner cartridge 32 toner is placed below the control valve 34. A space to draw in is formed.
In order to perform these operations, the control valve 34 must prevent the flat plate of the transport paddle 31d from being deformed with respect to the PET film thickness of 0.1 mm. Further, even if it is too thick (too hard), there are side effects such as an increased impact on the toner. When the paddle flat plate was made of the same PET material, a thickness of 0.188 mm was appropriate. By shifting the convex portions of the two flat plates of the transport paddle 31d, the pushing and releasing operations of the control valve 34 are alternately performed, so that the movement of the toner in the developing hopper 31h is improved and the circulation with the toner cartridge 32 is improved. Improved.

With the two-sheet paddle, the toner circulation and lateral agitation were improved, but with this two-sheet structure, the toner at the communication port 34 tends to increase, and the toner surface of the developing hopper 31h undulates in the vertical direction. Mountains and valleys are created. If there is a mountain at the communication port 34, toner replenishment is hindered, so that the total replenishment amount decreases.
In addition, since toner flows from the toner cartridge 32 at the base of the toner peak, the uniformity of toner stirring is slightly impaired.
As a result of examination to improve this point, when a blade having a length shorter than the two flat plates and having no unevenness was added between the two flat plates at an angle of 90 degrees, the toner of the communication port 34 was The mountain was broken and the toner surface in the developing hopper 31h was almost horizontal.
By doing so, in this transport paddle 31d, both the replenishment amount and the return amount are stable, a sufficient circulation action is achieved, and a local toner flow is not generated. Therefore, uniform stirring is performed in the developing hopper 31h. I was able to maintain sex.

FIG. 6 is a schematic diagram showing the configuration of the communication port of the developing unit. FIG. 7 is a schematic diagram illustrating the configuration of the communication port of the toner cartridge. Here, the shape of the toner supply passage (communication port) 33 between them will be described. The communication port 33 is formed by providing a plurality of holes through which toner enters and exits at almost the entire width of the image forming width, and toner replenishment and return are performed uniformly over the entire width. The control valve 34 described so far is arranged in each of the plurality of holes. The connecting portion is provided with an elastic member so that no gap is generated when the toner cartridge 32 is set. The communication port 33 is composed of a plurality of individual holes, and only an area less than half of the image forming width is opened. Similarly, since the communication port 33 of the slide shutter 32c is configured by a plurality of individual holes, the communication port 33 is closed when the slide shutter 32c moves.
The toner cartridge 32 is also provided with a slide shutter. By crushing an elastic member 32d made of foamed polyurethane or the like affixed to the toner cartridge 32 with a slide shutter 32c, the gap is eliminated and toner drop is prevented. Further, since the fixing seal is attached to the toner cartridge 32 from the outside, the hole of the slide shutter 32c is also closed by the fixing seal, and the toner remaining in each hole of the slide shutter 32c is blocked and does not fall. . There is a protrusion at the rear end of the slide shutter 32c, and the slide shutter 32c of the developing unit 31 is hooked and opened and closed. The elastic member 32c has a thickness of 0.5 mm to 3 mm to prevent toner dropping. Further, an elastic member 32c is further provided at the exit of the sliding portion of the toner cartridge 32. When the toner cartridge 32 is attached or detached, the slide shutter 32c is always rubbed by the elastic member 32c to prevent the toner from falling outside.

FIG. 8 is a schematic view showing the configuration of the developing device of the present invention. The example of FIG. 8 will be described. The toner replenished from the toner cartridge 32 to the developing hopper 31h by the operation of the control valve 34 falls downward from the communication port 33, and is agitated by the rotating agitating member 343 together with the toner of the developing hopper 31h on the spot, and a new toner The external additive such as hydrophobized silica is transferred to the toner of the developing hopper 31h (the amount of the additive on the surface is reduced as compared with the new toner) to restore the chargeability and fluidity. Further, by recoating with the external additive, the contact between the toner resins is suppressed, and the generation of the reversely charged toner is less likely to occur due to frictional charging between the new and old toners. In the conventional configuration, there is no space for the rotating agitating member 343 and the hopper wall surface and the bottom face along the rotation of the paddle 31d. However, when the paddle 31d rotates, the toner replenished from the toner cartridge 32 rides on the blade. Thus, the toner is sent to the developing roller 31a side. In addition, since the stirring force on the blades of the paddle 31d is small, if it is rotated on the blades several times, it may be stirred and mixed with the hot partner. Some of them are sent to the developing roller 31a side. Therefore, by rotating the rotating stirring member 343, the toner is not directly transferred to the paddle 31d from the communication port 33, but is rotated so that the toner is stirred in the space of the rotating stirring member 343 and then transferred to the paddle 31d. It is necessary to determine the rotation speed of the stirring member 343. Here, the rotational speed of the rotary stirring member 343 is set to 210 rpm with respect to the rotational speed of the paddle 31d of 66 rpm.
Although the set value varies depending on the size of the developing unit 31, the size of the space of the developing hopper 31h, and the flow characteristics of the toner, it is desirable to rotate the rotary stirring member 343 quickly. The rotation (rotation direction is CCW in FIG. 8) of the rotating agitating member 343 works to draw the toner replenished from the control valve 34, and the toner is first taken into the rotation path of the rotating agitating member 343. Further, since the rotation of the paddle 31d is slow, the toner of the developing hopper 31h serves to suppress the toner of the rotating stirring member 343 from being pushed out to the paddle 31d side. That is, while the toner replenished from the toner cartridge 32 is being stirred by the rotary stirring member 343, the toner is not conveyed to the developing roller side as it is, but after the stirring is achieved, the paddle 31d moves to the developing roller 31a side. It will be sent.
Further, since the toner swells at the upper part of the rotating stirring member 343, the toner in the developing hopper 31h enters the operating range of the control valve 34 from the upper part of the stirred toner, and the return operation of the control valve 34 removes the toner from the toner cartridge 32. The replenished toner is not immediately returned, and is sent once to the developing roller 31a side by the paddle 31d, and the toner returned from the toner is returned to the toner cartridge 32, and toner circulation throughout the developing device 30 is performed. Have achieved.

FIG. 9 is a diagram schematically illustrating the shape of the blades of the transport paddle.
The shape of the rotary stirring member 343 may be such that the A-type blade as shown in FIG. 5 is flat, and in this case, stirring in the radial direction around the rotation axis is positively performed. However, since the movement in the axial direction is small, the stirring action in the axial direction is slightly poor. Therefore, an example in which the blades are twisted to positively generate an agitating action also in the axial direction will be described.
The B type can generate a force for conveying toner in both directions. On the other hand, the C type generates a conveying force that draws toner toward the center. The angle of twist determines the conveying force in the axial direction and the conveying force in the radial direction, and determines the angle from the balance.
When the angle is lying, the conveying force in the axial direction is weak and the conveying (moving) force in the radial direction is present. On the other hand, as the angle is increased, the conveying force in the axial direction increases and the conveying force in the radial direction decreases. Further, since a shearing action occurs on the toner accumulation and a compressing action occurs on the aggregate of toner particles, if the angle is too large, the degree of aggregation of the toner is increased. Therefore, an appropriate angle setting is preferable.
In this example, good characteristics were obtained in the operation in the range of 15 to 45 degrees. That is, it is a condition that ensures the stirring property in the axial direction and suppresses the increase in the degree of toner aggregation.

Next, FIG. 10 is a schematic view showing another configuration of the developing device of the present invention. In this example, the drive cam 341 of the control valve 34 is used to drive the control valve 34. The drive cam of the control valve 34 is strong enough not to be deformed, and a metal shaft such as SUS has a cam shape. As described above, the cams corresponding to the control valves 34 are arranged so as to alternately drive the adjacent control valves 34. The drive cam of the control valve 34 is preferably arranged in the upper part of the hopper where toner does not reach. This is because if the cam is operated in a state where toner is sandwiched between the cam and the control valve 34, toner aggregates are easily generated. Compared with the conventional driving by the paddle 31d, since the driving force can be increased, the resilience can be increased by increasing the elastic modulus of the control valve 34. Whereas PET of 0.188mm thickness was used, thicker PET film, high elastic modulus, thin phosphor bronze plate and thin SUS plate, those that were stretched by pasting PET film on them Applicable. As a result, the amount of toner drawn from the toner cartridge 32 increases, and even if the toner in the developing hopper 31h stays in front of the control valve 34, it is not affected.
Further, when the control valve 34 is driven by the transport paddle 31d, the blades of the transport paddle 31d are forced to be deformed, and the push-in is slightly sweet. Since the driving performance is inferior and the control valve 34 is driven in accordance with the driving cycle, the rotational speed is slightly insufficient from the viewpoint of stirring. When the control valve 34 is driven by another driving mechanism as in this example, sufficient agitation of the toner is maintained.
It is desirable that the operation of the control valve 34 and the paddle 31d be constant in relation to the amount of toner supplied by the control valve 34 to the amount that the paddle 31d sends the toner to the developing roller 31a. This ratio is selected by setting the replenishment amount of the control valve 34.

パドル３１ｄと制御弁３４は整数比が望ましく、また回転撹拌部材３４３は、例３のように羽根の数が多く、十分回転が速いので整数でなくてもよい。 Further, since the toner inflow / discharge from the control valve 34 is affected by the toner flow in the developing hopper 31h, it is important to synchronize the timing so that the control valve 34 is driven when the position of the transport paddle 31d is the same. is there.
For example, each drive cycle and rotation cycle are determined at the following ratios.

The paddle 31d and the control valve 34 desirably have an integer ratio, and the rotary stirring member 343 does not have to be an integer because the number of blades is large and the rotation is sufficiently fast as in Example 3.

For the toner, in order to stably perform the operation by the control valve 34, the bulk density, which is one of the fluidity indexes, is preferably 0.4 to 0.6 g / cm ^3. Therefore, it is necessary to add an appropriate amount of hydrophobized silica that imparts fluidity. Depending on the characteristics of the toner base resin, the bulk density of the hydrophobized silica is 0.4 to 2.4 parts by weight with respect to the polyester resin toner. Although the amount fluctuated slightly, it was possible to realize toner circulation without problems in operation.
With this configuration, even in a color toner having a glass transition point of 70 ° C. or less and poor resistance to thermal stress and mechanical stress, it is possible to reduce the deterioration of the toner in the developing hopper 31h and the toner in the toner cartridge 32. Furthermore, since there is no difference in the degree of toner deterioration depending on the location in the hopper, (uniform toner characteristics), it was possible to suppress the occurrence of abnormal images due to toner deterioration.

  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 an image forming apparatus of the present invention. It is the schematic which shows the structure of the image development apparatus vicinity of this invention. FIG. 2 is a perspective view illustrating a configuration of a developing device of the present invention. 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. 6 is a schematic view showing a transport paddle used in a developing unit in the developing device according to the present invention. FIG. 2 is a schematic diagram illustrating a configuration of a communication port of a developing unit. FIG. 3 is a schematic diagram illustrating a configuration of a communication port of a toner cartridge. 1 is a schematic diagram illustrating a configuration of a developing device of the present invention. It is the figure which represented typically the shape of the blade | wing of a conveyance paddle. It is the schematic which shows the other structure of the image development apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Scanner unit 10 Photoconductor unit 11 Photoconductor belt 12 Photoconductor cleaning apparatus 13 Charging unit 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 Contact / Separation Mechanism 30 Developing Device 31 Developing Unit 31a Developing Roller 31b Supply Roller 31c Doctor Roller 31d First Conveying Paddle 31e Slide Shutter 31f Elastic Member 31g Window 31h Hopper 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 30f Chip 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 roller 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 66 Oil application unit 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 (11)

A developing unit for developing one-component toner on the electrostatic latent image on the image carrier;
A toner cartridge that is detachable from the developing unit and has a passage through which toner can pass in a horizontal direction between the developing unit and the developing unit;
In the developing device having a control valve for controlling supply / discharge of toner between the developing unit and the toner cartridge inside the developing unit, and further having a mechanism for periodically forming a space in the vicinity of the passage in the toner cartridge.
The developing device is characterized in that a first rotating stirring member is provided below the control valve. The developing device according to claim 1, wherein the first rotating stirring member has an acting force for conveying the toner to be stirred in the axial direction of the first rotating stirring member. The developing device according to claim 1, wherein the developing device includes a second rotating stirring member that conveys toner from the first rotating stirring member to the developing roller. The developing device according to claim 3, wherein the developing device also serves as a driving mechanism that provides a driving force for driving the control valve. The developing device according to claim 3, wherein the control valve and a driving mechanism thereof are provided above a toner surface in the developing unit. The developing device according to claim 3, wherein the first rotating stirring member has a higher rotational speed than the second rotating stirring member. The developing device according to claim 1, wherein a rotation frequency of the first rotating stirring member is higher than a driving frequency of the control valve. The developing device according to claim 3, wherein a drive frequency of the control valve is synchronized with rotation of the second rotating stirring member. 7. The developing device according to claim 1, wherein the developing device uses a toner having a bulk density in a range of 0.4 to 0.6 g / cm ³ and a glass transition point in a range of 60 to 90 ° C. The developing device according to any one of the above. 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 developing device according to claim 1 as the process cartridge. 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 is cleaned. An image forming apparatus comprising: a cleaning device that fixes the visible image on the recording member with heat and / or pressure;
The image forming apparatus according to claim 1, wherein the developing apparatus uses the developing apparatus according to claim 1.

Images