JP4284720B2 - Development device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a developing device that is used in, for example, an electrophotographic printer and supplies toner to an electrostatic latent image on a photoreceptor.
[0002]
[Prior art]
Conventionally, a developing device for supplying toner to an electrostatic latent image on a photoconductor used in an electrophotographic printer is in contact with the thickness of a toner layer adhering to the surface of a rotating developing roller over the width direction of the developing roller. The blade is made uniform. The blade of such a developing device is fixed inside the housing of the electrophotographic printer, and always contacts the developing roller while maintaining a constant angle and pressing force.
[0003]
[Problems to be solved by the invention]
However, as the printer prints, the toner in the developing device is charged with toner due to the external additive on the toner surface being driven into or peeled off from the toner base particles due to friction or collision in the developing device. Changes. Further, the pressing force of the blade against the developing roller changes due to the fusion of the toner to the blade.
[0004]
For this reason, even if the blade is fixed to the printer housing and kept in contact with the developing roller while maintaining a certain angle and pressing force, the toner is affected by the change in the chargeability of the toner and the influence of the toner fused to the blade. It is difficult to keep the layer thickness constant over a long period of time. In particular, the toner produced by the polymerization method has a spherical shape, and since there is no depression on the surface of the toner, the external additive on the toner surface is struck and peeled off to the toner base particles, and the thickness of the toner layer changes. It's easy to do.
[0005]
The present invention has been made to solve the above-described problems, and can suppress a change in the toner charging performance and a change in the thickness of the toner layer caused by the toner fusion to the blade. An object of the present invention is to provide a developing device capable of obtaining printing with a stable period.
[0006]
[Means for Solving the Problems]
[0007]
[0008]
[0009]
[0010]
[0011]
[0012]
[0013]
[0014]
[0015]
[0016]
The invention according to claim 1 is attached to the developing roller (4) for attaching the toner (TN) manufactured by the dispersion polymerization method to the electrostatic latent image on the photosensitive drum (1), and the developing roller (4). In a developing device comprising a blade (51) for uniforming the thickness of toner (TN) to be transferred and a toner cartridge, a pressing means (53, etc.) for pressing the blade (51) against the developing roller (4) The pressing means is disposed on the opposite side of the developing roller (4) across the blade (51), and is superimposed on the blade (51) so that the blade (51) is placed against the developing roller (4). An auxiliary plate (52 etc.) for increasing the contact pressure, an urging means (53 etc.) for pressing the auxiliary plate (52 etc.) against the blade (51), and a pressing means based on predetermined information (52,5 Control means (101) for controlling the pressing force of the control means (101), and the control means (101) increases the pressing force of the pressing means (53, etc.) when the toner cartridge is replaced. Increasing the contact pressure of the blade (51) against the developing roller (4), Furthermore, after increasing the pressing force of the pressing means, The contact pressure of the blade against the developing roller is lowered by lowering the pressing force of the pressing means (53, etc.) until the toner cartridge is newly replaced, and the thickness of the toner layer deposited on the developing roller is reduced. To regulate.
[0017]
According to the present invention, since the pressing force of the pressing means (52, 53) is controlled based on the predetermined information, the contact pressure of the blade (51) is appropriately controlled to enable stable printing.
Further, by suppressing the change in the thickness of the toner layer on the developing roller (4), the original performance of the toner (TN) produced by the polymerization method can be exhibited, and a high-definition image and high durability can be obtained. it can.
[0018]
According to a second aspect of the present invention, in the developing device according to the fifth aspect, the transfer means (9) for transferring the toner (TN) attached to the electrostatic latent image on the photosensitive drum (1) to the image receiving body (11). ) And counting means (102) for counting the number of times of transfer by the transfer means (9), and the control means (101) sets the count number of the counting means (102). Based on this, the pressing force of the pressing means is reduced Take control.
[0019]
According to this invention, since the pressing force of the pressing means (52, 53) is reduced based on the number of times of transfer by the transferring means (9), the contact pressure of the blade (51) can be appropriately controlled. .
[0020]
[0021]
[0022]
In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiment.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
-First embodiment-
A first embodiment in which the developing device of the present invention is applied to an electrophotographic printer (a laser printer for negatively charged toner) will be described below with reference to FIGS.
[0024]
FIG. 1 is a cross-sectional view of the developing device according to the first embodiment. The developing device includes a photosensitive drum 1 on which an electrostatic latent image is formed, a charging device 2 that charges the photosensitive drum 1, and a laser scanner 3 that emits light for forming an electrostatic latent image on the photosensitive drum 1. A developing roller 4 for attaching the toner TN to the electrostatic latent image on the photosensitive drum 1, a blade device 5 for making the thickness of the toner TN attached to the developing roller 4 uniform, and a toner TN on the developing roller 4. Supply roller 6, photosensitive drum 1, charging device 2, laser scanner 3, developing roller 4, blade device 5 and cover 8 for storing supply roller 6, and transfer roller provided opposite to photosensitive drum 1. 9 and a fixing mechanism 12 for fixing the toner TN attached to the paper 11. A toner storage unit 13 formed by recessing the cover 8 is provided adjacent to the supply roller 6. Arrows A, B, and C attached to the photosensitive drum 1, the developing roller 4, and the supply roller 6 indicate the respective rotation directions.
[0025]
As shown in FIG. 1 and FIG. 2A, the blade device 5 includes a blade 51 in which a bent portion 51 a formed at the tip is pressed against the developing roller 4 and a developing roller of the blade 51 by overlapping the blade 51. 4, the auxiliary plate 52 for uniformly increasing the contact pressure, the operation lever 54 having one end attached to the auxiliary plate 52 and the other end protruding outside the cover 8, and the operation lever 54 protruding from the cover 8. And a tension spring 53 interposed between the part and the cover 8. The operating lever 54 is urged by the spring 53 in a direction to rotate counterclockwise around the opening end 8 a of the cover 8, whereby the auxiliary plate 52 is pushed in the direction of the blade 51. As shown in FIG. 2B, when the operating lever 54 is operated to remove the spring 53 from the cover 8, the biasing force of the spring 53 does not act on the operating lever 54, so that the contact pressure of the blade 51 against the developing roller 4 Can be reduced. When the operation lever 54 in the state of FIG. 2B is operated to attach the spring 53 to the cover 8, the state returns to the state of FIG.
[0026]
In the present embodiment, the operation lever 54 can be driven not only by manual operation but also by an actuator 105 (FIG. 3). As will be described later, the contact pressure of the blade 51 is automatically set according to the number of printed sheets. It is configured to adjust and suppress fluctuations in print density. The actuator 105 can be switched back and forth between a state in which the spring 53 acts (state in FIG. 2A) and a state in which the spring 53 does not act (state in FIG. 2B).
[0027]
FIG. 3 is a block diagram showing a control system of the developing device. As shown in FIG. 3, a counter 102 for counting the number of printed sheets after toner cartridge replacement, an operation switch group 103 for receiving various instructions from the operator, a cartridge replacement detection device 104 for detecting toner cartridge replacement, and an operation lever 54 are provided. A lever driving actuator 105 for driving, the laser scanner 3, a feeding mechanism 106 for feeding paper 11, and a fixing mechanism 12 are connected to the control device 101.
[0028]
Next, an operation when the operation lever 54 is manually operated will be described.
[0029]
As shown in FIG. 1, the photosensitive drum 1 rotates at a constant speed in the direction of arrow A, and the surface thereof is uniformly charged by the charging device 2 to be charged. The charged photosensitive drum 1 is irradiated with image light by a laser scanner 3 to form an electrostatic latent image. The electrostatic latent image reaches a position facing the developing roller 4 as the photosensitive drum 1 rotates. Here, the toner TN adhering to the surface of the developing roller 4 is charged with the same polarity as the surface of the photosensitive drum 1, and is attached to the electrostatic latent image to be visualized.
[0030]
The toner TN is supplied from the toner storage unit 13 to the developing roller 4 by the supply roller 6. The toner TN attached to the surface of the supply roller 6 by the rotation of the supply roller 6 moves to the surface of the developing roller 4. Thereafter, the toner TN adhering to the surface of the developing roller 4 is made into a thin layer having a uniform thickness by the blade 51. The thin layer toner TN is attracted to and moved by the electrostatic latent image formed on the photosensitive drum 1 at the contact portion between the photosensitive drum 1 and the developing roller 4 to form a toner image as described above. The sheet 11 is conveyed in the direction of arrow D according to the rotation of the photosensitive drum 1, and the toner image on the photosensitive drum 1 is transferred onto the sheet 11 by the transfer roller 9. The sheet 11 on which the toner image has been transferred is conveyed to the fixing mechanism 12, where the toner image is fixed on the sheet 11 and printing is completed. In FIG. 1, reference numeral 14 denotes a fixed image.
[0031]
By the way, in general, as the printing is repeated, the charging characteristics of the toner in the developing device change as the external additive on the toner surface is driven into or peeled off from the toner base particles due to friction or collision in the developing device. To do. Further, the pressing force of the blade against the developing roller changes due to the fusion of the toner to the blade.
[0032]
For this reason, even if the blade is fixed and kept in contact with the developing roller 4 while maintaining a certain angle and pressing force, the change in the charging property of the toner and the influence of the toner fused to the blade cause an effect on the developing roller 4. It is difficult to always keep the thickness of the toner layer constant over a long period of time. In particular, the toner produced by the polymerization method has a spherical shape and no depression on the surface of the toner, so that the external additive on the toner surface is significantly driven into and peeled off from the toner base particle, and the thickness of the toner layer is large. Easy to change. In this case, the chargeability of the toner is reduced due to an increase in contact pressure due to the fusion of the toner to the blade, or the external additive on the toner surface being driven into or coming off from the toner base particles, and the fluidity of the toner is also reduced. . Therefore, the thickness of the toner layer on the developing roller tends to be small. For this reason, the print density decreases as printing is performed.
[0033]
On the other hand, in the developing device of the present embodiment, the spring 53 can be removed from the cover 8 by operating the operation lever 54, thereby adjusting the contact pressure of the blade 51. For this reason, the contact pressure of the blade 51 is adjusted in accordance with the operating state of the printer, and thereby the variation in the thickness of the toner layer formed on the developing roller 4 can be suppressed. For example, in order to prevent the toner layer on the developing roller 4 from becoming too thin, after the toner cartridge has been replaced and printed a certain number of times, the lever 53 is operated to remove the spring 53 from the cover 8; What is necessary is just to reduce the contact pressure of the blade 51 with respect to the developing roller 4. By such an operation, the contact pressure of the blade 51 is lowered at the time when the thickness of the toner layer is usually reduced after printing a certain number of sheets, so that the thickness of the toner layer is maintained. As a result, a sufficient print density can be maintained.
[0034]
Next, the operation in automatic control will be described. FIG. 4 shows processing in the control apparatus 101. In step S1 of FIG. 4, the pressure determination flag switched in step S5 or step S8 is read. If it is determined that the flag is off, that is, the blade pressure is high, printing is performed on one sheet. (Step S2), "1" is added to the count of the print counter 102 (step S3). Next, if it is determined that the count value of the print counter 102 has reached a predetermined number (step S4), the actuator 105 is driven to reduce the contact pressure of the blade 51, and the pressure determination flag is set. Turn on (step S5) and proceed to step S6. If it is determined in step S4 that the count of the print counter 102 has not reached the predetermined number, the process returns to step S2.
[0035]
On the other hand, if it is determined in step S1 that the pressure determination flag is ON, that is, it is determined that the blade pressure is low, a new toner cartridge is loaded (step S6), and the print counter 102 counts. The number is reset to “0” (step S7). Next, the actuator 105 is driven to increase the contact pressure of the blade, the pressure determination flag is turned off (step S8), and the process returns to step S2.
[0036]
As described above, in the process of FIG. 4, when a toner cartridge is newly loaded, the count number of the print counter 102 is reset and the blade pressure is increased. In addition, when the count number of the print counter 102 reaches a predetermined number, the print density is maintained by reducing the pressure of the blade. By setting the predetermined number used for the determination in step S4 to an appropriate value, it is possible to effectively suppress fluctuations in the print density due to the number of prints.
[0037]
The developing device of this embodiment is particularly effective when using a polymerized toner, particularly a toner produced by a dispersion polymerization method. The dispersion polymerization method is a polymerization method in which the monomer is dissolved in a solvent having a property that the monomer is dissolved but the polymer produced by the polymerization reaction is not dissolved. Easily obtain particles with a very narrow particle size distribution. Furthermore, particles having a substantially spherical shape can be obtained.
[0038]
Since the dispersed toner has a uniform particle size, a narrow charge amount distribution, and selective development is unlikely to occur, a high-definition image and high durability are expected. However, on the other hand, since the shape is spherical and there is no depression on the surface of the toner, the external additive on the toner surface is struck and peeled off from the toner base particles, so that the fluidity of the toner tends to be reduced. Since the chargeability of the toner tends to change, the thickness of the toner layer may change. Further, in the polymerization method, since the resin composition and molecular weight design are restricted, it is difficult to obtain polymer particles that are less likely to fuse the toner to the blade and have good fixing performance. For this reason, the contact pressure is likely to increase due to the fusion of the toner to the blade, and therefore the thickness of the toner layer on the developing roller tends to be small. For this reason, the print density may decrease as printing is performed.
[0039]
On the other hand, at the initial stage when the toner is filled, the thickness of the toner layer on the developing roller becomes excessive, and the print density is likely to be too high or fog is likely to occur. For this reason, it is necessary to bring the blade into contact with the developing roller with a strong contact pressure immediately after loading the toner so that the thickness of the toner layer does not become excessive. In the developing device of the present embodiment, immediately after replacing the toner cartridge, the blade is brought into contact with the developing roller with a strong pressure to suppress the thickness of the toner layer, and when a predetermined number of prints are performed, the operation lever 54 is operated. Or automatically by the processing of FIG. 4, the contact pressure of the blade to the developing roller is lowered. Thus, stable printing can be obtained by controlling the thickness of the toner layer not to be too thin.
[0040]
The decrease in the thickness of the toner layer and the accompanying decrease in the print density as described above are noticeable during the relatively initial printing of 5 to 50 sheets after the start of toner use. Alternatively, the auxiliary plate 52 may be automatically removed to reduce the contact pressure of the blade 51 to the developing roller 4.
[0041]
5 and 6 show an example of another blade device that replaces the blade device 5.
[0042]
As shown in FIG. 5, the blade device 5 </ b> A is configured to increase the contact pressure of the blade 51 to the developing roller 4 by overlapping the blade 51 with the bent portion 51 a being pressed against the developing roller 4. An auxiliary plate 52A, a compression spring 53A provided between the auxiliary plate 52A and the cover 8 and biasing the auxiliary plate 52A in the direction of the blade 51, one end of which can be brought into contact with the spring 53A, and the other end is a cover. 8 and an operation lever 54A protruding to the outside. By operating the operation lever 54A from the outside of the cover 8 and pushing the spring 53 downward in FIG. 5A, the spring 53A is removed from the auxiliary plate 52 as shown in FIG. The urging force can be prevented from acting. As a result, the contact pressure of the blade 51 with the developing roller 4 can be reduced. Although not shown in the figure, the state where the spring 53A does not act (the state shown in FIG. 5B) by a predetermined operation can be returned to the state where the spring 53A acts (the state shown in FIG. 5A). Is possible.
[0043]
On the other hand, the blade device 5B shown in FIG. 6A enhances the contact pressure of the blade 51 to the developing roller 4 by overlapping the blade 51 with the bent portion 51a pressed against the developing roller 4 and the blade 51. Between the cover 8 and the auxiliary plate 52B, the operation lever 54B having one end attached to the auxiliary plate 52B and the other end protruding to the outside of the cover 8, and the portion of the operation lever 54B protruding from the cover 8 A tension spring 53B. The auxiliary plate 52B is composed of two plate members joined via a hinge 55, and the auxiliary plate 52B can be bent via the hinge 55 as shown in FIG. In FIG. 6A, the operation lever 54B is urged counterclockwise by the spring 53B with the opening end 8a of the cover 8 as a fulcrum, and the auxiliary plate 52B is pushed in the direction of the blade 51. It is. As shown in FIG. 6B, when the operating lever 54B is operated to remove the spring 53B from the cover 8, the urging force of the spring 53B does not act on the operating lever 54B, so that the contact pressure of the blade 51 against the developing roller 4 Can be reduced. As shown in FIG. 6C, when the operation lever 54 </ b> B is further pulled up, the auxiliary plate 52 </ b> B is bent via the hinge 55, and the auxiliary plate 52 </ b> B can be pulled away from the blade 51. Thereby, the pressure from the auxiliary plate 52B to the blade 51 can be further reduced.
[0044]
In this embodiment, an example in which the blade pressure is controlled based on the number of printed sheets is shown. However, instead of performing control based on the number of printed sheets, for example, control based on the operating time of the printer after toner replacement may be performed. For example, the contact pressure of the blade may be reduced when it has been operated for a certain period of time. Further, the print density and the thickness of the toner layer on the developing roller may be detected by some sensor, and feedback control according to the detection result may be performed.
[0045]
Further, when the blade pressure is changed by automatic control, it is not always necessary to accept an operation for manually switching the pressure of the blade, and therefore an operation member corresponding to the operation lever 54 or the like may not be provided.
[0046]
In the above-described embodiment, the contact pressure of the blade can be switched in two stages. However, the contact pressure may be switched over three stages or more, and the contact pressure may be continuously variable.
[0047]
In the above embodiment, the contact pressure of the blade is reduced as the number of printed sheets increases, but depending on the type of toner and development conditions, the contact pressure of the blade is increased as the number of printed sheets increases. In some cases, variations in the thickness of the toner layer can be suppressed. In such a case, control may be performed to increase the contact pressure of the blade according to some information, such as increasing the pressure of the blade according to an increase in the number of printed sheets.
[0048]
【Example】
Next, a specific example of a toner manufacturing method will be described. First, a method for producing a polymerized toner (powder toner) used in the developing device will be described below. This polymerized toner is manufactured by a dispersion polymerization method.
[0049]
-Method for producing polymerized toner-
First, a method for producing polymer particles is performed. 465 parts by weight of methanol, 116 parts by weight of 2-propanol, 24 parts by weight of polyvinylpyrrolidone K-30, 154 parts by weight of styrene, acrylic acid in a reaction vessel equipped with a stirrer, condenser, thermometer and gas introduction tube 46 parts by weight of n-butyl and 12 parts by weight of α, α′-azobisisobutyronitrile were added. While stirring and dissolving this mixture at 100 rpm, nitrogen gas is purged from the gas introduction tube and heated to 60 ° C. Styrene and n-butyl acrylate are monomers, polyvinylpyrrolidone K-30 is a dispersant, and methanol and 2-propanol are solvents. After carrying out the polymerization for 13 hours, the mixture was cooled to 20 ° C. in 15 minutes with an ice-water bath, and the resulting polymer particles were collected by filtration, washed with methanol, and left to dry at room temperature for 48 hours. When the polymer particles thus obtained were observed with a scanning electron microscope, they were formed into a spherical shape. When the particle size was measured with a Coulter counter (Multisizer 2 manufactured by Coulter, Inc.), the volume average particle size was 7. The degree of dispersion was 5 μm and the particle size was 1.1.
[0050]
Next, a method for forming polymer particles into a toner will be described below.
[0051]
In 5 parts by weight of a saturated methanol solution of the dye Kayalon Polyester Black S200 (manufactured by Nippon Kayaku Co., Ltd.), 1 part by weight of the spherical polymer particles prepared by the above method was added with stirring to be dispersed. Further, stirring was continued for 1 hour at a temperature of 30 ° C., and the dyed spherical polymer particles were collected by filtration and then air-dried to obtain dyed spherical polymer particles.
[0052]
2 parts by weight of the charge control agent Spiron Black T-77 (Hodogaya Chemical Co., Ltd.) is added to 1000 parts by weight of the dyed spherical polymer particles, and 5 hours at 13000 rpm using a hybridization system (Nara Machinery Co., Ltd.). By performing the treatment for a minute, a charge control agent was injected into the dyed spherical polymer particles to obtain toner mother particles. Next, 1 part by weight of hydrophobic silica (manufactured by Wacker HDK H-2000) was stirred and mixed at 2750 rpm for 3 minutes with a Mechanomyl (manufactured by Okada Seiko Co., Ltd.) to obtain a black toner.
[0053]
-Print test-
Using the laser printer for negatively charged toner having the configuration shown in FIGS. 1 and 2, the toner storage unit 13 was filled with the above polymerized toner, and printing was performed. When 10 sheets were printed, the lever 54 was operated to lower the contact pressure of the blade 51, and printing was continued to print a total of 3000 sheets. As a result, as shown in the column of the example of FIG. 7, when the number of printed sheets is 1 to 3000 sheets, sufficient density printing is obtained, and the fog is also within a practical range. Note that the top row in FIG. 7 shows the total number of printed sheets. “Density” in Examples, Comparative Examples 1 and 2 represents transmission density. “Fog” is the difference between the reflectivity (%) before printing and the reflectivity (%) after printing in the area where white paper is not printed (white area). This value increases as more toner adheres to the surface.
[0054]
(Comparative Example 1)
The laser printer for negatively charged toner having the configuration shown in FIGS. 1 and 2 is modified, and the blade 51 is fixed so that the blade 51 always contacts the developing roller 4 with a strong contact pressure. The polymerization toner was filled and printing was performed. As shown in the column of Comparative Example 1 in FIG. 7, a decrease in the print density was observed, and the transmission density was less than 2.0, which is a practically sufficient density among a small number of printed sheets.
[0055]
Comparative Example 2 The laser printer for negatively charged toner having the configuration shown in FIGS. 1 and 2 is modified, and the blade 51 is fixed so that the blade 51 is always in contact with the developing roller 4 with a weak contact pressure to store the toner. Portion 13 was filled with the above polymerized toner, and printing was performed. As a result, as shown in the column of Comparative Example 2 in FIG. 7, the initial print density was excessively high, and fogging significantly exceeding the practical range of 1.0 was also observed. In this way, immediately after the start of printing, an auxiliary plate is attached to the blade and brought into contact with the developing roller with a strong pressure, and after printing 10 sheets, the pressure of the blade 51 is lowered, so that an image with sufficient density and no fog is obtained. Obtained. On the other hand, if the blade 51 is kept in contact with the developing roller 4 with a strong pressure, the print density decreases. Further, if the blade 51 is brought into contact with the developing roller 4 with a low pressure from the beginning, the print density becomes too high and fogging occurs while the number of printed sheets is small.
[0056]
【The invention's effect】
According to the first aspect of the invention, since the pressing force of the pressing means is controlled based on the predetermined information, the blade contact pressure is appropriately controlled to enable stable printing. Further, by suppressing the change in the thickness of the toner layer on the developing roller, the original performance of the toner produced by the polymerization method is exhibited, and a high-definition image and high durability can be obtained. Further, since the contact pressure of the blade can be adjusted by the control means, it is possible to suppress a change in toner charging performance and a change in the thickness of the toner layer caused by toner fusion to the blade. Stable printing can be obtained.
[0057]
[0058]
[0059]
[0060]
[0061]
[0062]
According to the second aspect of the present invention, since the pressing force of the pressing unit is reduced based on the number of times of transfer by the transferring unit, the contact pressure of the blade can be appropriately controlled.
[0063]
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a developing device according to an embodiment.
2 is a view showing a blade device provided in the developing device of FIG. 1. FIG. 2A is a view showing a state in which the spring functions and the contact pressure of the blade is high, and FIG. 2B is a view showing the spring. The figure which shows the state which is not functioning but the contact pressure of a braid | blade is low.
FIG. 3 is a control block diagram showing a control system of the developing device of FIG. 1;
FIG. 4 is a flowchart showing processing for switching the contact pressure of a blade.
FIGS. 5A and 5B are diagrams showing an example of another blade device, in which FIG. 5A shows a state in which the spring is functioning and the contact pressure of the blade is high, and FIG. 5B is a diagram in which the spring is not functioning; The figure which shows the state where the contact pressure of a braid | blade is low.
6A and 6B are diagrams showing an example of another blade device, in which FIG. 6A is a diagram showing a state where the spring is functioning and the contact pressure of the blade is high, and FIG. 6B is a diagram showing that the spring is not functioning. The figure which shows the state where the contact pressure of a braid | blade is low, (c) is a figure which shows the state which removed the auxiliary | assistant board from the braid | blade by pulling up an operation lever.
FIG. 7 is a diagram illustrating a result of a printing test.
[Explanation of symbols]
1 Photosensitive drum
4 Development roller
9 Transfer roller
11 paper
51 blade
52 Auxiliary plate
52A Auxiliary plate
52B Auxiliary plate
53 Tension spring
53A Compression spring
53B tension spring
54 Control lever
54A Operation lever
54B Operation lever
101 CPU
102 Print counter
TN toner

Claims (2)

Development comprising a developing roller for adhering toner produced by a dispersion polymerization method to an electrostatic latent image on a photosensitive drum, a blade for uniformizing the thickness of the toner adhering to the developing roller, and a toner cartridge In the device
Pressing means for pressing the blade against the developing roller;
The pressing means is disposed on the opposite side of the developing roller with the blade interposed therebetween, an auxiliary plate for overlapping the blade to increase the contact pressure of the blade against the developing roller, and the auxiliary plate as the blade An urging means for pressing toward the
Control means for controlling the pressing force of the pressing means based on predetermined information,
The control means increases the contact pressure of the blade against the developing roller by increasing the pressing force of the pressing means when the toner cartridge is replaced, and further increases the pressing force of the pressing means. Thereafter, the contact pressure of the blade against the developing roller is lowered by lowering the pressing force of the pressing means until a new toner cartridge is replaced, thereby regulating the thickness of the toner layer deposited on the developing roller. A developing device. A transfer unit that transfers the toner attached to the electrostatic latent image on the photosensitive drum to an image receiver; and a counting unit that counts the number of times of transfer by the transfer unit. The control unit is based on a count number of the counting unit. The developing device according to claim 1 , wherein control is performed to reduce a pressing force of the pressing unit.

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