JP3387569B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile and a printer, and more specifically, in a state where a developer carrying member is in contact with a developer carrying member.
An image forming apparatus equipped with a developing device that operates the developer carrying carrier to charge the developer carried on the developer carrying carrier to a predetermined potential to form a thin layer, and to carry the developer to the next process region. It is about.

[0002]

2. Description of the Related Art Conventionally, as an apparatus of this type, the developer carrying member is operated by operating the developer carrying member while the developer regulating member is in contact with the developer carrying member. A developer (one-component developer, two-component developer, etc.) carried on the toner is thinly charged while being charged to a predetermined potential by triboelectrification of the developer carrying carrier, the developer, and the developer regulating member. It is known that a developing device is provided which is layered and is conveyed to a next process region such as a developing region or a developer stirring region.

[0003]

However, in the image forming apparatus equipped with the above-described conventional developing device, a thin layer is formed on the developer carrying carrier when the developing device is intermittently operated or stopped during standby. The binding force between the developer and the developer carrying / conveying body, the developer regulating member, or the like is increased, and the developer is fixed on the developer carrying / conveying body. The carrying amount may become unstable or insufficient.

Therefore, in order to suppress and remove the sticking of the developer, in JP-A-2-203364, there is provided a magnetic brush roller in contact with a toner supply roller as a developer carrying / conveying body to supply the toner. It has been proposed to control the rotation speed of the roller while the magnetic brush roller is rotating. Further, in Japanese Unexamined Patent Publication No. 1-1165575, a toner scraping member that scrapes off a toner layer on a toner replenishing roller serving as a developer carrying / conveying body and replenishes it in a developing device,
It has been proposed that a charge eliminating member made of a conductive material is provided on the downstream side of the toner scraping member in the rotational direction of the toner replenishing roller so as to prevent the toner replenishing roller from being charged. Further, in JP-A-60-69665, provided impulsive force means for applying impulsive force to the lid member of the developing equipment,
It has been proposed that prior to the development, the impact force of the impact means is applied to the lid member to forcibly remove the toner adhering to the seal member or the like due to the impact. Further, Japanese Patent Application Laid-Open No. 61-286867 proposes a device in which a conductive member is provided in the vicinity of a developing sleeve of a developing device, and the toner adhering to the surface of the developing sleeve is adsorbed and collected by the conductive member. There is. However, in the configuration proposed above, it is necessary to newly provide some member, device or the like for preventing the toner sticking.

The present invention has been made in view of the above problems, and it is an object of the present invention to stabilize the developer from the developer carrying carrier to the next process area without providing new members, devices and the like. It is to provide an image forming apparatus that can be supplied as a sheet.

[0006]

[0007]

In order to achieve the above object, the invention of claim 1 provides a developer carrying carrier for carrying and carrying the developer toward the developer carrying body in the next process area. ,
By operating the developer carrying carrier with the developer regulating member in contact with the developer carrying member, the developer carried on the developer carrying carrier is charged to a predetermined potential to form a thin layer. In an image forming apparatus equipped with a developing device that conveys to a region,
Voltage applying means for applying a voltage to the developer carrying carrier,
Before the normal operation of the developer carrying carrier, the voltage is applied so that a voltage for generating an electric field in the direction of moving the developer on the developer carrying carrier to the next process area is applied in advance. A control means for controlling the means is provided.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect , voltage applying means for applying a voltage to the developer carrying carrier and before the normal operation of the developer carrying carrier is started. A first voltage for generating an electric field in a direction to move the developer on the developer carrying carrier to the next process area, and an electric field in a direction to move the developer in the next process area to the developer carrying carrier. It is characterized in that a control means for controlling the voltage applying means is provided so as to sequentially apply the second voltage for generating the voltage.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect , the application time of the first voltage V1 is T.
1, and when the application time of the second voltage V2 is T2, V1 = V2 and T1 = T2 are satisfied.

Further, the invention of claim 4, the image forming apparatus according to claim 1, 2 or 3, based on the history of the stop time of the developer carrying carrier, whether to apply the above SL proactive voltage A control means for controlling the application time of the preceding voltage or the preceding voltage is provided.

[0011] The invention of claim 5 is the image forming apparatus according to claim 1, 2 or 3, based on the time history of the developer carrying carrier, whether to apply the above SL proactive voltage,
A control means for controlling the application time of the preceding voltage or the preceding voltage is provided. Here, the time history is the total operating time of the developer carrying carrier.

[0012] The invention of claim 6 is the image forming apparatus according to claim 1, 2 or 3, the developer carrying conveyor of the installation environment (e.g., humidity) based on, the upper Symbol proactive voltage It is characterized in that a control means for controlling whether or not the voltage is applied, the application time of the preceding voltage, or the preceding voltage is provided.

[0013]

According to a seventh aspect of the present invention, in the image forming apparatus according to the second aspect, in which the developer carrying member in the next process area operates periodically, the application time of the first voltage and the each second voltage application time and current of said next process zone
It is characterized in that it is set to an integral multiple of the operation cycle of the image carrier .

[0015]

[0016]

According to the invention of claim 1, the developer carrying carrier is operated while the developer regulating member is in contact with the developer carrying carrier carrying and carrying the developer. the developer carried on the developer carried and conveyed member, charged to a thin layer to a predetermined potential, that the developer carrying member is provided
It is transported to the next process area. The binding force of the developer carried on the developer carrying carrier increases due to the intermittent operation of the developing device or the stoppage of the operation during standby, and the developer is fixed on the developer carrying carrier to the next process area. The developer transport amount may become unstable or insufficient. Therefore, before the normal operation of the developer carrying carrier is started by the control means, a voltage for generating an electric field in a direction to move the developer on the developer carrying carrier to the next process area is applied in advance. The voltage applying means is controlled so as to do so. This allows
The binding force between the developer which is fixed on the developer carrying carrier and is hard to separate and the developer carrying carrier is weakened, and the developer is carried out by the normal operation of the developer carrying carrier. So that they can be transported properly.

According to a second aspect of the present invention, by the control means, the electric field in a direction for moving the developer on the developer carrying carrier to the next process area before the normal operation of the developer carrying carrier is started. Voltage applying means for sequentially applying a first voltage for generating the electric field and a second voltage for generating an electric field in the direction in which the developer in the next process area moves to the developer carrying carrier. To control. Thus, in case of performing the application of the upper Symbol proactive voltage, the developer is prevented from being excessively transferred from the developer carrying carrier to said next process zone.

In the invention of claim 3, when the application time of the first voltage V1 is T1 and the application time of the second voltage V2 is T2, V1 = V2 and T1 = T
Each voltage and application time are set so as to satisfy 2. As a result, when subjected to application of the upper Symbol proactive voltage,
Do not change the amount of the developer in the next process area.

[0019] In the invention of claim 4, in the control means, based on the history of the stop time of the developer carrying carrier, whether to apply the above SL proactive voltage, application time of said prior specific voltage , Or control the preceding voltage. For example, if the stop time is long, or subjected to application of proactive voltage, or a longer application time of the proactive voltage, or to increase the said prior specific voltage. As a result, the binding force between the developer and the developer carrying carrier, which is firmly fixed on the developer carrying carrier and difficult to separate during the stop time, is weakened, and regardless of the length of the stop time, The developer can be properly conveyed to the next process area by the normal operation of the developer carrying and conveying body.

[0020] In the invention of claim 5, in the control means, based on the time history of the developer carrying carrier, whether to apply the above SL proactive voltage, application time of said prior specific voltage, or Control the preceding voltage. For example, if該経time history is short, or subjected to application of proactive voltage, or a longer application time of the <br/> proactive voltage, or to increase the said prior specific voltage. Thus, it weakens the binding force between the time history in the developer carried and conveyed developer is less likely apart bonded onto body and developer carrying carrier, the length of the time history <br/> Nevertheless, the developer can be properly conveyed to the next process area by the normal operation of the developer carrying and conveying body .

[0021] In the invention of claim 6, in the control means, based on the installation environment of the developer carrying carrier, whether to apply the above SL proactive voltage, application time of said prior specific voltage, or Control the preceding voltage. For example, if the humidity of the installation environment is low, or subjected to application of proactive voltage, or a longer application time of the proactive voltage, or to increase the said prior specific voltage. This weakens the binding force between the developer that is fixed on the developer carrying carrier and is hard to separate in the installation environment and the developer carrying carrier, and the developer is irrelevant regardless of the installation environment. The normal operation of the carrying and transporting body enables the developer to be properly transported to the next process area.

[0022]

According to a seventh aspect of the invention, the application time of the first voltage and the application time of the second voltage applied to the developer carrying member are respectively set in the next process area.
By setting the integral multiple of the operation cycle of the developer carrying member, the respective application time, so that the operation of the developer carrying member of the at least one said next process area is performed.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a color electrophotographic copying machine (hereinafter referred to as a copying machine) which is an image forming apparatus will be described below. FIG. 2 is a schematic configuration diagram of the copying machine according to the present embodiment. This copying machine obtains a color image by superposing and transferring a plurality of images of different colors from a photosensitive drum on the same transfer paper, and a scanner unit 31 for reading an original document and this scanner unit 31.
An image processing unit 32 that electrically processes a digital image signal from the printer, and a printer unit 33 that forms a color image on a transfer sheet based on the image signal of each color from the image processing unit 32.
It has and.

In the scanner unit 31, the original placed on the original table 34 is illuminated by the light source 35, and the reflected light image passes through the mirrors 36 to 38 and the imaging lens 39 and is, for example, BK by the dichroic prism 40. (Black) R (Red), G (Green), B (Blue)
Are separated into respective colors and image-formed on the light receivers 41 to 43 including CCD. Then, the movable optical system including the light source 35 and the mirrors 36 to 38 is moved to perform sub-scanning of the original,
The light receivers 41 to 43 photoelectrically convert the incident light image while performing main scanning, and then perform A / D conversion to convert the image signal into BK, R, G, and B image signals, which are output to the printer unit 33. In this case, the BK, R, G and B image signals may be Y, M and C image signals.

In the printer section 33, four sets of BK, R, G, and B images are formed by the BK, R, G, and B image signals from the image processing section 32, respectively, and are superposed and transferred onto a transfer sheet. recording device 44BK, 44Y, 44M, 44
C, and these recording devices 44BK, 44Y, 44
M and 44C are photosensitive drums 45BK, 45Y, and
45M, 45C, laser light 46BK, 46Y, 46M,
Image exposure laser light emitting devices 47BK, 47Y, 47M and 47C for emitting 46C respectively, charging chargers 48BK, 48Y, 48M and 48C, developing device 49B.
K, 49Y, 49M, 49C, transfer charger 50B
K, 50Y, 50M, 50C, cleaning device 51B
It has K, 51Y, 51M, 51C and the like.

In the recording device 44C, the photosensitive drum 45C
Is driven to rotate by the main motor, and the charging charger 4
8C, the electrostatic latent image of the C image is formed by exposure with the laser beam 46C from the image exposure laser beam emitting device 47C. In this case, the image exposure laser light emitting device 47C modulates and drives the laser light source by the C image signal from the image processing unit 32, and the laser light 46C having the intensity corresponding to the C image signal is emitted from the laser light source to the photosensitive drum 45C.
Irradiate to.

The electrostatic latent image on the photosensitive drum 45C is developed by a developing device 49C with a two-component developer containing C toner and carrier (hereinafter referred to as developer) to become a visible image composed of a C toner image. It is transferred by the transfer charger 50C onto the transfer paper on the conveyor belt 52. Paper feeding device 53, 54
Contains two types of transfer paper, and the selected one feeds the transfer paper to the registration roller 57 by the paper feed rollers 55 and 56. The registration roller 57 sends the transfer paper to the conveyor belt 52 at a predetermined timing. The conveyor belt 52 is the roller 5
8 to 60 are rotated and driven to convey the transfer paper sent from the registration roller 57, and the C toner image on the photoconductor drum 45C is transferred to the transfer paper by the transfer charger 50C as described above. . Further, the cleaning device 51C has a toner removing brush roller and a charge eliminating device, and removes the residual toner on the photosensitive drum after the transfer of the C toner image.

The recording devices 44BK, 44Y and 44M perform the image forming operation similarly to the recording device 44C. That is, the image exposure laser light emitting devices 47BK, 47Y, and 47M modulate the laser light sources by M, Y, and BK image signals from the image processing unit 32 to drive the laser light sources M, Y, and B, respectively.
Laser light 46BK, 46 having an intensity corresponding to the K image signal
Y, 46M of the photosensitive drum 45BK, 45Y, irradiated to 45M, the photoreceptor drum 45BK, 45Y, 45M is a charger 48BK, 48Y, laser light is uniformly charged by 48M 46BK, 46Y, BK in exposure with 46M , Y, M electrostatic latent images are formed.

These electrostatic latent images are developed by developing devices 49BK, 4
9Y and 49M develop with a developer containing BK toner, Y toner, M toner, and carrier, respectively, to form a visible image composed of a BK toner image, a Y toner image, and an M toner image, which is transferred to a transfer paper on the conveyor belt 52. Charger 50BK, 5
0Y and 50M are transferred so as to overlap with the C toner image so as to form a full-color image. Further, the transfer sheet on the conveyor belt 52 is fixed by the fixing device 61 after the transfer of the visible image, and is discharged to the outside by the conveyor roller 62. In addition, the conveyor belt 52 has a charge eliminator 63 after the transfer paper is conveyed.
The residual charge is erased by the belt cleaning device 6
4 removes the residual toner.

FIG. 3 is a front view showing a schematic configuration of each of the developing devices 49Y, 49M, 49C and 49BK which are image forming units. Developing devices 49Y, 49M, 49
Since the C and 49BK basically have the same configuration,
Here, the subscripts of Y, M, C, and BK used in the reference numerals of the members to indicate the correspondence with the toner colors are omitted .

Referring to FIG. 3, in the developing device 49 of this example, a hollow cylindrical developing sleeve and a fixed magnet built in the developing sleeve are partially exposed from the opening toward the photosensitive drum. A developing roller 70 including a group (not shown) is provided. Then, in the developing device 49, a toner replenishing roller 71 as a developer carrying / conveying body provided so as to face the developing roller 70, vertical conveying rollers 72, 73, vertical conveying screws 74, 75, and a developing device. A developing doctor 76 which also serves as a left side wall of 49 is provided. Further, a replenishing sponge roller 77 and a thinning blade 78 as a developer regulating member are arranged so as to come into contact with the surface of the toner replenishing roller 71, and above the replenishing sponge roller 77, an agitator 79 and a toner conveying screw 80. Is provided.

The developing sleeve of the developing roller 70 is made of a conductive non-magnetic material such as aluminum, and a developing bias voltage is applied by a developing bias power source (not shown) as needed. In addition, the toner supply roller 71
Is a core member made of a conductive material such as metal, on which a resistor layer (surface layer) made of silicon rubber resin or the like is formed. A replenishing bias voltage is applied to the core member as needed by a replenishing bias power source (not shown) as a voltage applying means. Further, as the material of the thinning blade 78, a material having appropriate elasticity such as a thin plate metal such as carbon steel can be used. Further, as the supply sponge roller 77, a core member made of a conductive material such as metal,
Examples thereof include those obtained by subjecting a foamed polyurethane to a conductive treatment by dispersing carbon, etc., and winding it. In addition,
When selecting the materials for the toner replenishing roller 71, the replenishing sponge roller 77, and the thin layer blade 78, the charging polarity of the toner, the required charging amount, and the like are taken into consideration.

The upper and lower conveying rollers 72 and 73 are
A block magnet having N and S poles is built in, and is rotated counterclockwise so that the developer from the developing roller 70 is pumped up and conveyed. Above upper conveying screw 74
Rotates counterclockwise within the gutter-shaped screw casing 83, drops the developer received from the screw casing 83 from the peripheral surface of the upper conveying roller 72, and conveys the developer to the inner side of the developing device. There is. An unillustrated opening for dropping a developer is formed in a lower portion of the screw casing 83 on the back side, and an unillustrated overflow opening in the width direction is formed in a side wall opposite to the upper and lower conveying rollers 72, 73. . The lower conveying screw 75 rotates counterclockwise in the developer pool above the developing roller 70,
The developer is conveyed from the back side of the developing device to the front side.

In the developing device 49, the lower end is attached to the peripheral wall of the developing device 49, and the upper end is in contact with the toner replenishing roller 71 at a predetermined pressure. The replenishing roller seal 81, the toner replenishing roller 71, and the thinning blade 78. ,as well as,
A developing stirring chamber in which the developing roller 70 and the like are arranged and the agitator are formed by a partition wall formed by a blade holder 82 having an upper portion attached to the lower end portion and an upper end portion attached to the peripheral wall of the developing device. 79
And the like are divided into a toner storage chamber. Then, in the toner storage chamber, the upper toner transport screw 8
The toner sent from a toner tank (not shown) via 0 is stored in the developing and stirring chamber, and a developer including the carrier and the toner replenished from the toner storing chamber via the toner replenishing roller 71 is stored in the developing agitating chamber. It is housed. In the figure, reference numeral 84 is a right casing forming the right side surface of the toner storage chamber, reference numeral 85 is an upper cover forming the upper surface of the storage chamber, and reference numeral 86 is developer replenishment forming the upper surface of the developing stirring chamber. The port cover, reference numeral 87, respectively represents a developing casing that constitutes the lower surface of the developing stirring chamber.

The operation of the developing device 49 will be described. The fixed magnet group holds the developer on the peripheral surface of the developing sleeve of the developing roller 70. When the developing sleeve rotates in the counterclockwise direction, the developer carried on the developing sleeve is conveyed, the height of the brush is regulated by the developing doctor 76, and the developing area between the developing roller 70 and the photosensitive drum 45 is formed. Be transported. Then, the electrostatic latent image on the photosensitive drum 45 is developed and visualized by a developing bias voltage applied from a developing bias source (not shown).

When the developing operation is performed, the test pattern previously formed on the photosensitive drum 45 is also developed,
The optical density of the visualized test pattern is detected by the photosensor 88 as an image density detecting means. The detection result is compared with the reference density, the toner concentration in the developer at the present time is determined, and when it is determined that the toner concentration is low, the toner replenishing roller 71 arranged close to the developing roller 70 is When a toner replenishing clutch such as a magnet clutch (not shown) is turned on, the toner rotates in a counterclockwise direction. A replenishing sponge roller 77, a thinning blade 78, and a replenishing roller seal 81 are pressed against the peripheral surface of the toner replenishing roller 71 and the entire area in the axial direction.
The toner in the toner accommodating chamber is rubbed onto the toner replenishing roller 71 by the replenishing sponge roller 77 which rotates at the same time as the toner replenishing roller 71, and is conveyed along with the rotation of the toner replenishing roller 71 and then onto the toner replenishing roller 71 by the thinning blade 78. It is continuously thinned.

The thinned toner on the toner replenishing roller 71 is charged to a predetermined polarity, that is, the negative electrode in this embodiment by a series of frictional actions, and this negatively charged toner is carried on the developing roller 70. Contact the developer that is being used. At this time, the core of the toner replenishing roller 71 is controlled by the replenishing bias power source so that the negatively charged toner on the toner replenishing roller 71 forms an electric field moving to the developing roller 70 side between the developing roller 70 and the toner replenishing roller 71. Apply a replenishment bias voltage to the member. As a result, the toner on the toner replenishing roller 71 is supplied to the developer on the developing roller 70, and the toner concentration in the developer is kept within a certain range.
Here, the potential difference between the developing sleeve of the developing roller 70 and the toner replenishing roller 71, that is, the potential difference between the developing bias voltage and the replenishing bias voltage is called the toner replenishing potential.

The developer that has passed between the developing roller 70 and the toner replenishing roller 71 is located at a position facing the lower conveying roller 73, and the magnetic force of the lower conveying roller 73 causes the lower conveying roller 73 to move.
Pumped up to. The developer drawn up by the lower carrying roller 73 is further drawn up by the upper carrying roller 72, and when it reaches a portion beyond the top of the carrying roller 72 and where there is no influence of the magnetic force on the screw casing 83 side, Thus, it falls by its own weight over the entire width and is received by the screw casing 83. Then, it is conveyed to the inner side of the developing device by the lower conveying screw in the screw casing 83 and falls from the developer dropping opening formed in the lower portion of the inner side of the screw casing 83. Further, part of the developer received by the screw casing 83 also drops from the overflow opening. Then, the developer dropped from the developer dropping opening or the carver flow opening forms a developer pool above the developing roller 70, and is moved to the inner side of the developing device by the lower carrying screw 75 in the developer pool. Be transported. In this way, the vertical conveying screws 74, 75
The developer that has been sufficiently cross-mixed by the developer is carried on the developing roller 70 by the magnetic force of the developing roller 70 and conveyed, and is regulated to a predetermined thickness by the developing doctor 76 on the way, and then a portion facing the photosensitive drum. Be transported to.

By the way, as in this embodiment, the developing device 45
When it is configured to be small, it becomes difficult to stir and mix the developer and the replenished toner in a developer stirring region for a sufficient time, so the replenished toner is thinned as much as possible,
It is desired to be sufficiently charged. But on the other hand,
When a high charge amount is applied to the toner, the toner supply roller 71
It becomes difficult for the toner to separate from the top. Moreover, as the stop time of the toner replenishing roller 71 becomes longer, the coupling force between the thin layer charged toner on the toner replenishing roller 71 and the toner replenishing roller 71 becomes larger, and it becomes more difficult to separate them.

Therefore, in this embodiment, before the toner replenishing operation by the normal operation of the toner replenishing roller 71, the toner replenishing roller 71 (and the replenishing sponge roller 77) is operated in advance for a predetermined time so as to perform the predetermined replenishment. A control means for applying a bias voltage to the toner supply roller 71 is provided. As this control means, the control unit 100 used in the copying machine of this embodiment can be used.

FIG. 1 is a block diagram of control according to this embodiment. The control unit 100 includes a CPU 100a and a ROM 10
0b, RAM 100c, I / O interface 100
I / O interface 100d
A signal from a photo sensor 88, a humidity sensor 89 that detects the installation environment of the copying machine, a copy start switch 90, and the like is input via a control signal to a replenishing bias power source 71a, a developing bias power source 70a, a toner replenishing clutch 71b, and the like. Is output.

FIG. 4A is a graph showing changes over time in the ON / OFF control signal VCL and the replenishment bias voltage VH of the toner replenishment clutch 71b in the conventional toner replenishment control, and FIG. 4B shows the present embodiment. 6 is a graph showing a time change of the ON / OFF control signal VCL and the replenishment bias voltage VH in the toner replenishment control of the example. Here, symbol A indicates a period of the toner replenishing operation by the operation of the normal toner replenishing roller 71, symbol B indicates a period of the preceding toner replenishing operation (1 second) performed before the normal toner replenishing operation, The symbol C indicates the copy operation time.

In the period (C) during copying, a developing bias voltage of -560V is applied to the developing sleeve of the developing roller 70, and in this period (C), the toner replenishing roller is set to zero the toner replenishing potential. The replenishment bias voltage VH0 (= -560V) having the same potential is also applied to 71. In addition, the toner replenishing roller 7 for normal toner replenishment
While 1 is rotated (A), in order to form a predetermined toner replenishment potential, a predetermined replenishment bias voltage V
H1 is applied. The toner replenishing operation is performed at the same timing as the developing operation of the image portion on the photosensitive drum 45.

In this embodiment, as shown in FIG. 4B, immediately after the copy start switch 90 is pressed to start the copy operation, the toner supply clutch 71b is preceded by the normal toner supply operation (A). Is turned on, and the toner supply roller 71 is operated in advance. In the first half T1 of the preceding operation period B, the replenishment bias voltage (VH0−ΔVH) as the first voltage V1 for generating the electric field for moving the negatively charged toner from the toner replenishment roller 71 to the developing roller 70 side. ) Is applied to the toner supply roller 71,
In the second half T2 of the period B, the replenishment bias voltage (VH0 + ΔVH) as the second voltage V2 for generating the electric field for moving the negatively charged toner from the developing roller 70 side to the toner replenishing roller 71 side is supplied. It is applied to the roller 71. Here, the periods T1 and T2 are set to be equal.

The preceding operating time (B) of the toner replenishing roller 71 and the value of ΔVH are previously stored in the ROM 100.
b or the matrix of Table 1 stored in the RAM 100c.

[Table 1] Here, the time history is the total rotation time of the toner supply roller 71, which is reset to zero when the roller is replaced. The installation environment (humidity) is humidity data of the installation environment of the developing device 49 detected by the humidity sensor 89. The stop time history is the time from when the toner supply roller 71 was operated last time until the next copy start switch is pressed.

In Table 1 above, for example, the history of time is 2
If it is less than time, the installation environment (humidity) is 65% RH, and the stop time history is 5 minutes, the toner replenishing roller 71 is operated in advance for 1 second.
A replenishment bias voltage of −560V ± 300V is applied to the first terminal.

As described above, according to the present embodiment, the direction in which the toner replenishing roller 71 is operated in advance and the toner on the toner replenishing roller 71 is moved to the developing roller 70 before the normal operation of the toner replenishing roller 71 is started. The replenishment bias voltage VH for generating the electric field is applied. This weakens the coupling force between the toner that is fixed on the toner replenishing roller 71 and is difficult to separate from the toner replenishing roller 71, and the toner is properly transferred to the developing roller 70 by the normal operation of the toner replenishing roller 71 thereafter. Allow it to be transported. Therefore, since the toner thinned on the toner replenishing roller 71 is highly charged, if a document having a large image area is intermittently copied, the replenishment becomes insufficient even if the continuous replenishment movement is performed.
Even when the density is reduced, the toner is stably replenished, the toner is replenished in time, and the density is not reduced. Further, unlike the conventional case, it is not necessary to provide a new member or device.

Further, according to this embodiment, the toner on the toner replenishing roller 71 is moved to the developing roller 70 as the replenishing bias voltage VH applied before the start of the normal operation of the toner replenishing roller 71. A voltage V1 for generating an electric field and a voltage V2 for generating an electric field in a direction to move the toner on the developing roller 70 to the toner replenishing roller 71.
Is sequentially applied in advance, the toner is not excessively conveyed from the toner replenishing roller 71 to the developing roller 70 during the preceding operation of the toner replenishing roller 71.
Further stable toner supply is performed.

Further, according to this embodiment, the replenishment bias voltage VH in the preceding operation of the toner replenishing roller 71 is set.
Is set so as to satisfy V1 = V2 and T1 = T2, the toner density of the developer on the developing roller 70 does not change, and more stable toner supply is performed.

Further, according to the present embodiment,
Since the preceding operation time of the toner replenishing roller 71 and the replenishment bias voltage VH applied at that time are controlled based on the installation environment (humidity) and the stop time history, the above history and stop time history Regardless of the length and the size of the installation environment (humidity), the toner can be properly conveyed to the developing roller 70 by the normal operation of the toner replenishing roller 71, and stable toner replenishment can always be performed.

The toner replenishing roller 71 of the above embodiment is used.
In the preceding operation, the rotation speed of the toner supply roller 71 may be increased instead of lengthening the time of the preceding operation. In this case, the preceding operation time can be shortened.

Further, in the above embodiment, the replenishment bias voltage V1 during the preceding operation of the toner replenishing roller 71 is set.
It is preferable that the application times T1 and T2 of V2 and V2 are set to integral multiples of the operation cycle of the developing roller 70 which is the mechanism of the developing area. In this case, the developing roller 7 of one cycle is applied during the preceding application times T1 and T2 during operation.
The operation of 0 is performed at least once, so that the toner density of the developer on the developing roller 70 is not uneven, and the stable developing operation can be performed.

In the above embodiment, the toner replenishing roller is used as the developer carrying / conveying body, but instead of this, a developer carrying / conveying body composed of a belt may be used.

Further, in the above embodiment, the two-component type developer comprising the toner and the carrier is used, but the present invention can be applied to the image forming apparatus using the one-component type developer.

[0056]

[0057]

Effects of the Invention According to the present invention, in the control unit, before the start of normal operation of said developer carrying conveying member, the developer on the current <br/> image-carrying carrier following The voltage applying means is controlled so that the voltage for generating the electric field in the direction of moving to the process area is applied in advance. As a result, the binding force between the developer that is fixed on the developer carrying carrier and is hard to separate from the developer carrying carrier is weakened, and the developer is carried out during normal operation of the developer carrying carrier. It can be properly conveyed to the next process area. Therefore, even if the chargeability of the developer on the developer carrying carrier is high, the developer is stably supplied from the developer carrying carrier to the next process area without providing a new member or device. The effect is that you will be able to.

Further, according to the invention of claim 2, the control means moves the developer on the developer carrying carrier to the next process area before the normal operation of the developer carrying carrier is started. The first voltage for generating the electric field in the direction and the second voltage for generating the electric field in the direction for moving the developer in the next process region to the developer carrying carrier are sequentially applied in advance. controlling the voltage applying means, thereby, in the case of the application of the upper <br/> Symbol proactive voltage, the developer is prevented from being excessively transferred from the developer carrying carrier to said next process zone Therefore, there is an effect that the developer can be more stably supplied from the developer carrying carrier to the next process area.

Further, according to the invention of claim 3, the first
And the second voltage V2
When the application time of T2 is T2, V1 = V2 and T1
= Each voltage and application time to satisfy T2,
Thus, in the case of the application of the upper Symbol proactive voltage,
Since the amount of the developer in the next process area is not changed, there is an effect that the developer can be more stably supplied from the developer carrying carrier to the next process area.

Further, according to the inventions of claims 4 to 6, the controller controls the stop time history of the developer carrying carrier, the time history of the developer carrying carrier, or the developer carrying carrier. based on the installation environment, whether to apply the above SL proactive voltage, application time of said prior specific voltage, or by controlling the said prior specific voltage, the length of該経time history and the stop time history Regardless of the size of the installation environment (humidity) or the size of the installation environment (humidity), the developer can be properly conveyed to the next process area by the normal operation of the developer carrying carrier. This has the effect of enabling stable supply at all times.

[0061]

According to the invention of claim 7, the application time of the first voltage and the application time of the second voltage to be applied to the developer carrying member are respectively determined by the current time of the next process area.
By setting an integral multiple of the operating cycle of the image carrier ,
At each application time, at least once in the next process area
Since the operation of the developer bearing member is performed, unevenness of the developer in the next process area does not occur, and a stable developing operation can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram of control according to an embodiment.

FIG. 2 is a schematic configuration diagram of a copying machine according to an embodiment.

FIG. 3 is a schematic configuration diagram of a developing device of the copying machine.

FIG. 4A is a graph showing changes over time in an ON / OFF control signal and a replenishment bias voltage of a conventional toner replenishment clutch.
FIG. 6B is a graph showing changes over time in the ON / OFF control signal of the toner replenishment clutch and the replenishment bias voltage according to the embodiment.

[Explanation of symbols]

45 photoconductor drum 49 Developing device 70 developing roller 70a Development bias power supply 71 Toner supply roller 71a Supply bias power supply 71b Toner supply clutch 78 Thinning blade 100 control unit

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Norihiro Kurami 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Yuji Sawai 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 In stock company Ricoh (72) Inventor Souta Fujimori 1-3-3 Nakamagome, Ota-ku, Tokyo Satoshi Hatori (72) Inventor Satoshi Hatori 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 Within Ricoh Co., Ltd. (56) Reference JP-A-5-100563 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15/08 507 G03G 15/08 501 G03G 21/14

Claims (7)

(57) [Claims] 1. A developer carrying member for carrying and carrying a developer toward a developer carrying member in a next process area, wherein the developer carrying member is brought into contact with a developer regulating member. In an image forming apparatus equipped with a developing device that is operated to charge the developer carried on the developer carrying body to a predetermined potential to form a thin layer, and carry the developer to the next process area. Voltage applying means for applying a voltage to the body, and a voltage for generating an electric field in a direction for moving the developer on the developer carrying carrier to the next process area before the normal operation of the developer carrying carrier is started. An image forming apparatus comprising: a control unit that controls the voltage application unit so as to apply the voltage in advance. 2. A voltage applying means for applying a voltage to the developer carrying carrier, and the developer on the developer carrying carrier to the next process area before the normal operation of the developer carrying carrier is started. A first voltage for generating an electric field in a moving direction and a second voltage for generating an electric field in a direction in which the developer in the next process area moves to the developer carrying carrier are sequentially applied in advance. The image forming apparatus according to claim 1, further comprising control means for controlling the voltage applying means. 3. When the application time of the first voltage V1 is T1 and the application time of the second voltage V2 is T2, V1 = V2 and T1 = T2 are satisfied. The image forming apparatus according to item 2. 4. Based on the history of the stop time of the developer carrying carrier, whether to apply the above SL proactive voltage, application time of said prior specific voltage, or control for controlling the said prior specific voltage An image forming apparatus according to claim 1, 2 or 3, further comprising means. 5. Based on the time history of the developer carrying carrier, whether to apply the above SL proactive voltage, application time of said prior specific voltage, or a control means for controlling said prior specific voltage The image forming apparatus according to claim 1, wherein the image forming apparatus is provided. 6. Based on the installation environment of the developer carrying carrier, whether to apply the above SL proactive voltage, application time of said prior specific voltage, or a control means for controlling said prior specific voltage The image forming apparatus according to claim 1, wherein the image forming apparatus is provided. 7. The image forming apparatus according to claim 2, wherein the developer carrying member in the next process area is cyclically operated, wherein the application time of the first voltage and the application time of the second voltage are 3. The image forming apparatus according to claim 2, wherein each is set to an integral multiple of the operation cycle of the developer carrier in the next process area.