JPH08314253A - Method and device for forming image - Google Patents

Abstract

PURPOSE: To provide a method and a device for forming an image capable of restraining deterioration caused by the stirring friction of developer even when the developer is stirred for a long time in a state where neither the consumption nor the replenishment of toner is not performed in the developer container part of a developing device. CONSTITUTION: In a color copying machine, the developer in the developer container part of the developing device of a recorder 44 is stirred and carried to a developing area opposed to a photoreceptor drum so as to develop a latent image formed on the photoreceptor drum, and the developer which is not used for development in the developing area is restored to the developer container part, and the developer container part is replenished with the toner as necessary. The copying machine is provided with a control part 100 controlling the recorder 44 so that the latent image to forcibly consume the toner is formed on the photoreceptor drum and developed to make the toner adhere to the photoreceptor drum, and the developer container part may be forcibly replenished with the toner when the developer is stirred for a specified time or more in the state where neither the consumption nor the replenishment of the toner is not performed in the developer container part.

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 machine, a printer, etc., and more specifically, a developer in a developer accommodating portion is agitated and the developer is opposed to an image carrier. The latent image formed on the image bearing member is conveyed to an area to be developed, and the developer not used for development in the developing area is returned to the inside of the developer accommodating section, and if necessary, is stored in the developer accommodating section. The present invention relates to an image forming method for replenishing toner by replenishing toner and a technique for reducing deterioration due to agitation of a developer in the apparatus.

[0002]

2. Description of the Related Art Conventionally, in the image forming apparatus of this type, if the developer in the developer accommodating portion is continuously agitated for a long time, deterioration due to agitating friction of the developer is accelerated. Therefore, in order to prevent the deterioration of the developer due to stirring friction, the developer in the developer accommodating portion is not stirred unless the toner in the developer accommodating portion is consumed and replenished by a normal image forming operation. It is known to do so.

[0003]

However, depending on the specific configuration of the image forming apparatus, due to the mechanical limitation of the image forming apparatus, the toner is not consumed or replenished in the developer accommodating portion by the normal image forming operation. In some cases, stirring of the developer may not be stopped. For example, in the case of an image forming apparatus including a plurality of latent image carriers and an image forming unit corresponding to each latent image carrier, and driving all or a plurality of latent image carriers and image forming units by one driving device, During the image forming operation of the entire apparatus, all or a plurality of latent image carriers and the corresponding image forming units are continuously driven, and the inside of the developer accommodating portion is in a state where the toner in the developer accommodating portion is not consumed and replenished. The developer is continuously stirred for a long time.

If the developer is continuously stirred for a long time in the state where the toner is not consumed and replenished in the developer accommodating portion as described above, there is no or almost no balance of the toner. Stirring friction between them continues for a long time, and the deterioration of the developer is accelerated, which may cause deterioration in image quality and developing ability at a time earlier than the normal life of the developer. More specifically, the stirring friction between the same toner and the carrier, the stirring friction between the same toner and the stirring friction between the same carriers continue for a long time, and the toner adheres to the surface of the carrier and the toner due to scraping and cracking. Deterioration of the developer such as reduction in diameter is accelerated. Then, the charging ability of the developer is deteriorated earlier than the normal life of the developer, which may result in deterioration of image quality such as background smear and deterioration of developing ability leading to deterioration of gradation reproducibility.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a case where the developer is agitated for a long time without consumption and replenishment of the toner in the developer accommodating portion. However, it is an object of the present invention to provide an image forming method and apparatus capable of suppressing deterioration of a developer due to stirring friction.

[0006]

In order to achieve the above object, the invention of claim 1 stirs the developer in the developer accommodating portion and conveys the developer to a developing area facing the image carrier. To develop the latent image formed on the image bearing member, return the developer not used for development in the developing area into the developer containing section, and replenish toner into the developer containing section as necessary. In the image forming method, the toner in the developer accommodating portion is forcibly consumed when the developer is stirred for a predetermined time or longer without the toner in the developer accommodating portion being consumed or replenished, It is characterized in that the toner is forcibly replenished into the agent container.

According to a second aspect of the present invention, a latent image forming means for forming a latent image on the image carrier, a developer stirring means for stirring the developer in the developer accommodating portion, and a developer agitating means in the developer accommodating portion. And a developer carrying member which carries the developer and supplies it to a developing area facing the image carrying member, and which returns the developer not used for developing the latent image on the image carrying member into the developer containing section. In an image forming apparatus provided with a toner replenishing means for replenishing toner to the developer accommodating portion as necessary, a toner consuming means for forcibly consuming the toner in the developer accommodating portion and an inside of the developer accommodating portion When the developer is agitated for a predetermined time or longer in a state where the toner is not consumed, the toner in the developer accommodating portion is forcibly consumed and the toner is forcibly replenished in the developer accommodating portion. Controlling the toner consuming means and the toner replenishing means It is characterized in that provided and that the control unit.

According to a third aspect of the invention, in the image forming apparatus according to the second aspect, the latent image forming means and the developer carrying member are used as the toner consuming means, and the toner is forcibly consumed. The latent image forming means and the developer carrier so that a latent image for forcibly consuming toner is formed on the image carrier, and the latent image is developed to adhere the toner to the image carrier. It is characterized by controlling.

According to a fourth aspect of the invention, as the toner replenishing means, a toner replenishing member for carrying the toner in the toner accommodating portion and replenishing it in the developer accommodating portion, and a voltage for applying a voltage to the toner replenishing member. 3. The image forming apparatus according to claim 2, further comprising an applying unit, wherein the toner replenishing member and the voltage applying unit are used as the toner consuming unit, and the toner carried on the toner replenishing member is removed and collected. A recovery unit is provided, and when the toner is forcibly consumed, a voltage is applied to the toner replenishing member to generate an electric field in a direction in which the toner in the developer containing portion moves toward the toner replenishing member. After the toner in the developer accommodating portion is carried on the toner replenishing member, the toner replenishing member and the voltage applying hand are so arranged as to remove and collect the toner on the toner replenishing member. And characterized in that for controlling the toner recovery unit.

[0010]

In the image forming method according to claim 1 or the image forming apparatus according to claim 2, the developer is agitated for a predetermined time or more without consumption and replenishment of the toner in the developer accommodating portion. By forcibly consuming the toner in the container and forcibly replenishing the toner in the developer container,
The toner concentration of the developer in the developer accommodating portion is not largely changed, and stirring of the developers makes it difficult for the same developers to continuously rub against each other for a long time.

Particularly, in the image forming apparatus according to the third aspect, the latent image forming means forms a latent image for toner forcible consumption on the image carrier, and the developer carrier supplies the developer to the developing area. By developing the latent image and adhering the toner onto the image carrier, the toner in the developer accommodating portion is forcibly consumed. The toner adhered on the image carrier due to the compulsory consumption of the toner can be removed by a cleaning unit used in normal image formation.

Further, in the image forming apparatus according to the present invention, the voltage applying means applies a voltage to the toner replenishing member to generate an electric field in a direction in which the toner in the developer containing portion moves toward the toner replenishing member. After the toner in the developer accommodating portion is carried on the toner replenishing member, the toner on the toner replenishing member is removed and collected by the toner collecting means, whereby the toner in the developer accommodating portion is forcibly consumed. Note that when the toner is forcibly replenished into the developer container,
As in the case of normal image formation, a voltage for generating an electric field in the direction in which the toner is moved from the toner replenishing member into the developer accommodating portion by the electric field applying means is applied to the toner replenishing member, so that the toner in the toner accommodating portion is removed. To be replenished in the developer accommodating portion.

[0013]

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 section 31, a document placed on a document table 34 is illuminated by a light source 35, and a reflected light image thereof passes through mirrors 36 to 38 and an imaging lens 39 and is, for example, BK by a 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 perform photoelectric conversion on the incident light image while performing main scanning, and then convert it into a digital signal by A / D conversion.
This digital signal is subjected to necessary processing in the image processing unit 32, and recording color information of each color, for example, BK (black), C
(Cyan), M (magenta), and Y (yellow) image signals are converted and output to the printer unit 33.

In the printer section 33, BK, C, M, and Y images are formed by the BK, C, M, and Y image signals from the image processing section 32, respectively, and are superimposed on a transfer sheet as a transfer material. 4 sets of recording devices 44BK and 44 for transferring
Y, 44M, 44C, and these recording devices 44B
K, 44Y, 44M and 44C are photosensitive drums 45BK, 45Y, 45M, 45C and 4 as image bearing members, respectively.
A set of latent image forming means, four sets of developing devices 49BK, 49Y,
49M, 49C, transfer chargers 50BK, 50Y, 5
0M, 50C, a cleaning device 51BK as a cleaning means for cleaning the surface of each photosensitive drum,
It has 51Y, 51M, 51C and the like. The latent image forming means are laser beams 46BK, 46Y, 46M and 46, respectively.
Image exposure laser light emitting device 4 for emitting C respectively
7BK, 47Y, 47M, 47C and charging charger 4
8BK, 48Y, 48M, 48C, etc., and each of the developing devices 49BK, 49Y, 49M, 49C is divided into a developer accommodating portion and a toner accommodating portion, which will be described later, in which a developing roller as a developer bearing member is disposed. Has been done. In this embodiment, a color image is formed with four colors BK, C, M and Y, but one set of recording devices may be reduced so as to form a color image with three colors.

Further, in the printer section 33, as described above, four sets of photosensitive drums 45BK, 45Y, 45M, 4 are set.
5C and the recording devices 44BK, 44Y, 44M, and 44C are juxtaposed, and are configured to perform high-speed copying by transporting the transfer paper from the paper feed unit to the paper discharge unit in one pass. In order to achieve such a high speed copying operation and to maintain the developing characteristics, the copying machine according to the present embodiment has the number 1 as shown in FIG.
The main motor 90 as one drive source is configured to drive the respective driving members of the recording devices 44BK, 44Y, 44M, and 44C including the four photoconductor drums 45BK, 45Y, 45M, and 45C and the developing device. . The rotational driving force of the main motor 90 is transmitted to the worm shaft 92 via the timing belt 91, and the worm gears 92Y, 92M, 92C, 9 formed on the worm shaft 92.
2BK and worm wheel 93Y, 93M, 93C,
Driving members (upper and lower conveying rollers 72, 73 and upper and lower conveying screws 74, 75, etc., which will be described later) in each photoconductor drum and each recording device are driven via 93BK or the like. As described above, in the copying machine of this embodiment, the photosensitive drums 45B of the respective colors are used.
K, 45Y, 45M, 45C and recording devices 44BK, 4
The 4Y, 44M, and 44C drive members cannot be independently driven.

The recording devices 44BK, 44Y, 44M,
For example, in the recording device 44C of 44C, the photosensitive drum 45
The C is rotationally driven by the main motor 90 and uniformly charged by the charging charger 48C, and an electrostatic latent image of the C image is formed by exposure with the laser light 46C from the image exposure laser light 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 a carrier (hereinafter referred to as a developer) to form 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 photosensitive drum 45C is transferred to the transfer paper 50C.
Is transferred. 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.

Other color recording devices 44BK, 44Y, 44
M performs an image forming operation similarly to the recording device 44C. That is, the image exposure laser light emitting devices 47BK, 47Y, 4
Reference numeral 7M denotes a laser light source 46B having an intensity corresponding to the M, Y, and BK image signals from the laser light source by modulating and driving the laser light source by the M, Y, and BK image signals from the image processing unit 32.
K, 46Y, 46M to the photoconductor drums 45BK, 45Y,
It irradiates 45M, and photoconductor drums 45BK, 45Y, 45
M is uniformly charged by the charging chargers 48BK, 48Y and 48M, and electrostatic latent images of BK, Y and M are formed by exposure with the laser beams 46BK, 46Y and 46M.

These electrostatic latent images are developed by the developing devices 49BK, 4BK.
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. 4 shows the developing devices 49Y, 49M,
It is a front view which shows schematic structure of 49C and 49BK. Since the developing devices 49Y, 49M, 49C, 49BK have basically the same configuration, here, the Y, M, C, BK used in the member reference numerals to show the correspondence with the toner color is described. The subscript is omitted.

In the developing device 49 shown in FIG. 4, a hollow cylindrical developing sleeve and a group of fixed magnets and the like built in the developing sleeve are partially exposed through the opening toward the photosensitive drum. A developing roller 70 is disposed as a developer carrying member (illustrated). Then, the developing device 49
Inside, a toner replenishing roller 71 as a toner replenishing member provided so as to face the developing roller 70, upper and lower conveying rollers 72, 73 and upper and lower conveying screws 74, 75 as developer stirring means, and the left side of the developing device 49. A developing doctor 76 also serving as a wall is arranged. Further, a replenishing sponge roller 77 and a thinning blade 78 are arranged so as to contact the surface of the toner replenishing roller 71, and an agitator 79 and a toner conveying screw 80 are arranged above the replenishing sponge roller 77. A storage unit is provided. (Hereinafter, margin)

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 as necessary by a developing bias power source (not shown). 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 by a replenishing bias power source (not shown) as a voltage applying means, if necessary. In addition, the thinning blade 78
Examples of the material include materials having appropriate elasticity such as thin plate metal such as carbon steel. The replenishing sponge roller 77 may be, for example, a core member made of a conductive material such as metal and wound around a core member that has been subjected to a conductive treatment by dispersing carbon in foamed polyurethane. The toner supply roller 71, the supply sponge roller 77,
In selecting the material for the thinning blade 78, the charging polarity of the toner, the required charging amount, etc. are taken into consideration.

Further, the upper and lower conveying rollers 72, 73 as the developer agitating means have a built-in block magnet having two magnetic poles of N pole and S pole, and rotate counterclockwise so as to move from above the developing roller 70. The developer is drawn up and conveyed. The upper conveying screw 74 rotates counterclockwise in the gutter-shaped screw casing 83, falls from the peripheral surface of the upper conveying roller 72, and falls into the screw casing 8
The developer received in 3 is conveyed to the back side of the developing device. 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 reservoir above the developing roller 70 and conveys the developer from the back side of the developing device to the front side.

In the inside of the developing device 49, the lower end is attached to the peripheral wall of the developing device 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, and a blade holder 8 in which the upper part of the thinning blade 78 is attached to the lower end and the upper end is attached to the peripheral wall of the developing device.
The developing roller 7 is composed of a partition wall composed of two.
0 and the like, the developer accommodating portion and the agitator 79 described above.
And the like are disposed in the toner storage portion. The toner storage portion includes an upper toner transport screw 80.
The toner sent from a toner tank (not shown) via the toner container is accommodated, and the developer accommodating portion is filled with the developer including the carrier and the toner replenished from the toner accommodating portion via the toner replenishing roller 71. It is housed. In the figure, reference numeral 84 is a right casing that constitutes the right side surface of the toner storage portion, reference numeral 85 is an upper cover that constitutes the upper surface portion of the storage chamber, and reference numeral 86 is developer replenishment that constitutes the upper surface portion of the developing agitation chamber. The port cover, reference numeral 87, respectively represents a developing casing that constitutes the lower surface of the developing stirring chamber.

In the developing device 49 having the above structure, the developer is carried on the peripheral surface of the developing sleeve of the developing roller 70 by the fixed magnet group. 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, by the developing bias voltage applied from a developing bias source (not shown), the photosensitive drum 4
The electrostatic latent image on 5 is developed and visualized.

When the developing operation is performed, the toner density control sensor pattern previously formed on the photosensitive drum 45 is also developed, and the optical density of the visualized sensor pattern is shown in FIG. 5 (a). It is detected by a photo sensor 88 as an image density detecting means having the characteristic of. 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. The peripheral surface of the toner replenishing roller 71, the replenishing sponge roller 77, the thinning blade 78, and the entire area in the axial direction,
The replenishing roller seal 81 is pressed against the toner, and the toner in the toner containing portion is rubbed against the toner replenishing roller 71 by the replenishing sponge roller 77 which rotates at the same time as the toner replenishing roller 71. Toner supply roller 71 by means of the liquefying blade 78
It is continuously thinned on top.

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 defined as the toner replenishing potential Vh.
The toner supply potential Vhp and the amount of toner replenished from the toner storage unit to the developer storage unit per unit time are referred to as p, and a relationship as shown in, for example, FIG. 5B is established.

The developing roller 70 and the toner replenishing roller 7
The developer that has passed between 1 is entirely pumped up to the lower transport roller 73 by the magnetic force of the lower transport roller 73 at a position facing the lower transport roller 73. 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 conveying screw 75 in the developer pool. Be transported. The developer that has been sufficiently cross-mixed by the upper and lower conveying screws 74 and 75 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. After that, the sheet is conveyed to a developing area in a portion facing the photosensitive drum.

Further, in the copying machine of the present embodiment, the sensor pattern for controlling the image quality is controlled by the charger 48 of the recording device 44 and the laser light emitting device 47 for image exposure at a predetermined timing, for example, every time a copy operation of a predetermined number of sheets is completed. Is formed and visualized by the developing device 49, the image density of this sensor pattern is read by the photosensor 88. Then, based on the output of the photosensor 88, the developing bias voltage applied to the developing roller 70 and the charging charger 48.
At least one of the charging potential on the photoconductor drum 45 and the writing light amount of the image exposure laser light emitting device 47 is controlled in a timely manner to stabilize the image quality.

By the way, as in this embodiment, the developing device 49
Then, as described above, in order to maintain the developing characteristics of the developer, the stirring circulation of the developer is repeated in the developing container,
In the recording device 44 in which the image is not formed, the stirring and circulation of the developer is repeated in a state where the toner is not consumed and replenished, so that the stirring friction between the same developers (toner and carrier) continues for a long time. Degradation accelerates, and there is a possibility that image quality and developing ability may deteriorate at a time earlier than the normal life of the developer.

Therefore, in this embodiment, the developer is agitated for a predetermined period of time or more without toner consumption and replenishment in the developer accommodating portion, or when it is expected that the agitation will be performed. The charging charger 48 of the recording device 44, the developing roller 70, the developing roller 70, so as to forcibly consume the toner in the accommodating portion and forcibly replenish the toner in the developer accommodating portion.
A control unit for controlling the toner supply roller 71 and the like is provided. As this control means, the control unit 100 used in the main body of the copying machine of this embodiment can be used.

FIG. 1 is a block diagram of the control system of the copying machine of this embodiment. The control unit 100 includes a CPU 100a and RO
The I / O interface 1 includes an M100b, a RAM 100c, an I / O interface 100d, and the like.
A signal from the operation panel 94, the image processing unit 32, or the like is input via 00d, and the charging charger 4 of the recording device 44 is input.
8, image exposure laser light emitting device 47, developing device 49,
A control signal is output to the cleaning device 51, the toner supply clutch 71b, and the like.

In the above control system, it is determined whether or not the developer is already stirred for a predetermined time or more in a state where the image forming operation is not performed and the toner is not consumed and replenished. It is determined whether or not it is expected to be presented. For example, the user can use the operation panel 94 to perform image processing and copy number, which are unique to a digital copying machine, such as using a document that does not include cyan color elements, erasing the cyan color elements in the document, or converting to other color elements. The user gives instructions via an editor, etc., and based on the content of the instructions,
Whether or not the developer is already stirred for a predetermined time or more in a state where the cyan recording apparatus does not perform the image forming operation and the toner is not consumed and replenished, or when the developer is stirred for a predetermined time or more. It can be judged whether or not it is expected. Further, the above determination can be made based on the data from the image processing unit 32 described above. Here, the above-mentioned predetermined time is set based on the balance of the balance of the toner that does not burden the life of the developer due to the deterioration characteristics of the developer used in the developing device 49 over time.

Then, it is judged that the stirring of the developer has been performed for a predetermined time or longer without the consumption and replenishment of the toner in the developer accommodating portion of the developing device 49, or the stirring of the developer is expected to be performed for the predetermined time or more. If it is determined that the predetermined amount of toner is forcibly consumed from the developer accommodating portion after the series of set number of copy operations being executed at that time is finished, the toner is consumed at the same time as the toner consumption. By controlling the replenishment bias voltage applied from the replenishment clutch 71b and the replenishment bias power source 95, the toner amount is forcibly replenished from the toner accommodating portion to the developer accommodating portion. Here, the predetermined toner amount is set based on the toner balance pace that does not burden the developing ability of the developer used. Further, the toner consumption amount and the toner replenishment amount do not necessarily have to be set to the same amount, but they are preferably set to the same amount in order to keep the toner concentration of the developer in the developer accommodating portion more constant.

The toner is forcibly consumed as follows. First, a toner consumption pattern similar to the above-described sensor pattern is formed over the entire image formation width for a time corresponding to a predetermined toner amount, and the development device 49 visualizes the pattern.
Due to this visualization, the toner in the developer accommodating portion of the developing device 49 adheres to the pattern on the photosensitive drum 45 and is forcibly consumed. The toner on the visualized pattern is removed by the cleaning device 51 without being transferred to the transfer paper. Here, the creation time of the toner consumption pattern can be obtained, for example, by dividing the toner consumption amount forcibly consumed by dividing the toner consumption amount per unit time by the pattern visualization. Further, the toner consumption amount per unit time due to the pattern visualization can be obtained by multiplying the image forming width, the image forming speed, and the toner adhesion amount per unit area of the pattern.

As described above, according to the present embodiment, it is expected that the stirring of the developer is performed for a predetermined time or more without the consumption and the replenishment of the toner in the developer accommodating portion of the developing device 49. At this time, the toner in the developer accommodating portion is forcibly consumed and the toner is forcibly replenished in the developer accommodating portion, so that the toner concentration of the developer in the developer accommodating portion is not significantly changed. Stirring makes it difficult for the same developers to continuously rub against each other for a long time, and even if the developer is stirred for a long time without consumption and replenishment of the toner in the developer accommodating section, Deterioration can be suppressed.

Further, according to the present embodiment, the recording device 44 forms a latent image of a pattern for forced toner consumption on the photosensitive drum 45, visualizes the latent image, and adheres the toner. The recording device 44 used for normal image formation is diverted, and the toner in the developer accommodating portion in the developing device 49 can be forcibly consumed without providing a separate device.

In the above embodiment, the toner is forcibly consumed by adhering the toner onto the photosensitive drum 45 and removing the toner with the cleaning device 51. Supply potential Vh
The toner in the developer accommodating portion is carried on the toner replenishing roller 71 by switching the positive and negative of p, and the toner on the toner replenishing roller is scraped and removed by the toner scraping device as a toner collecting means, and the toner is stored in the collecting container. The toner in the developer accommodating portion may be forcibly consumed by controlling the toner to be collected. In this case, the cleaning operation by the cleaning device 51 is not necessary, and the cleaning device 51 other than the developing device need not be burdened.

[0040]

According to the image forming method of the first aspect or the image forming apparatus of the second aspect, when the developer is agitated for a predetermined time or more without the consumption and the replenishment of the toner in the developer accommodating portion. The toner concentration of the developer in the developer accommodating portion is forcibly consumed by forcibly consuming the toner in the developer accommodating portion and forcibly replenishing the toner in the developer accommodating portion. The developer is agitated for a long time without consumption and replenishment of the toner in the developer accommodating portion because the same developer is not easily frictioned continuously for a long time by agitating the developer without making a large change. Even in such a case, the deterioration of the developer due to friction by stirring can be suppressed.

Particularly, according to the image forming apparatus of claim 3,
A latent image for compulsory toner consumption is formed on the image carrier by the latent image forming means, a developer is supplied to the developing area by the developer carrier to develop the latent image, and toner is attached to the image carrier. By doing so, the latent image forming means and the developer carrying member used for normal image formation can be diverted, and the toner in the developer accommodating portion can be forcibly consumed without providing a separate device.

Further, in particular, according to the image forming apparatus of the fourth aspect, the voltage applying means applies the voltage for generating the electric field in the direction in which the toner in the developer accommodating portion moves toward the toner replenishing member to the toner replenishing member. After the toner in the developer accommodating portion is carried on the toner replenishing member, the toner in the developer accommodating portion is forcibly consumed by removing the toner on the toner replenishing member by the toner removing means. It is not necessary to operate the forming means and the developer bearing member for the forced toner consumption, and the burden on the cleaning means for the surface of the image bearing member is not imposed.

[Brief description of drawings]

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

FIG. 2 is a schematic configuration diagram of the copying machine.

FIG. 3 is a schematic configuration diagram of a drive system of the copying machine.

FIG. 4 is a schematic configuration diagram of a developing device used in the copying machine.

FIG. 5A is a characteristic diagram of a photo sensor. FIG. 6B is a characteristic diagram showing the relationship between the toner replenishment potential and the toner replenishment amount.

[Explanation of symbols]

 44 recording device 45 photoconductor drum 47 laser light emitting device for image exposure 48 charging charger 49 developing device 50 transfer charger 51 cleaning device 70 developing roller 70a developing bias power source 71 toner replenishing roller 71a replenishing bias power source 71b toner replenishing clutch 72 upper conveying roller 73 Lower Conveying Roller 74 Upper Conveying Screw 75 Lower Conveying Screw 78 Thinning Blade 100 Control Unit

Claims (4)

[Claims] 1. A developer in a developer accommodating portion is stirred, and the developer is conveyed to a developing area facing the image carrier to develop a latent image formed on the image carrier, and the developing area is developed. In the image forming method, in which the developer not used for the development is returned to the developer accommodating portion, and the toner is replenished to the developer accommodating portion as needed, the toner in the developer accommodating portion is not consumed or replenished. In this state, when the developer is stirred for a predetermined time or longer, the toner in the developer containing section is forcibly consumed and the toner is forcibly supplied into the developer containing section. . 2. A latent image forming means for forming a latent image on an image bearing member, a developer stirring means for stirring a developer in a developer accommodating portion, and a developer in the developer accommodating portion for supporting the developer. A developer carrying member which supplies the developer not used for developing the latent image on the image carrying member into the developer containing part while supplying the developer to the developing area facing the image carrying member, and the developer containing part. In an image forming apparatus provided with a toner replenishing means for replenishing toner as necessary, a toner consuming means for forcibly consuming the toner in the developer accommodating section and a state in which no toner is consumed in the developer accommodating section. The toner consuming means and the toner consuming means are configured to forcibly consume the toner in the developer accommodating portion and forcibly replenish the toner in the developer accommodating portion when the developer is stirred for a predetermined time or more. A control means for controlling the toner supply means is provided. And an image forming apparatus. 3. The latent image forming means and the developer carrying member are used as the toner consuming means, and when the toner is forcibly consumed, a latent image for forced toner consumption is formed on the image carrying body. 3. The latent image forming means and the developer carrying member are controlled so that the latent image is formed and the latent image is developed to adhere the toner onto the image carrying member.
Image forming apparatus. 4. The toner replenishing means includes a toner replenishing member for carrying the toner in the toner accommodating portion and replenishing it in the developer accommodating portion, and a voltage applying means for applying a voltage to the toner replenishing member. In the image forming apparatus of item 2, the toner replenishing member and the voltage applying means are used as the toner consuming means, and a toner collecting means for removing and collecting the toner carried by the toner replenishing member is provided. When the toner in the developer accommodating portion is forcibly consumed, a voltage for generating an electric field in the direction in which the toner in the developer accommodating portion moves toward the toner replenishing member is applied to the toner replenishing member to remove the toner in the developer accommodating portion. The toner replenishing member, the voltage applying means, and the toner collecting means so that the toner on the toner replenishing member is removed and collected after being carried on the toner replenishing member. Image forming apparatus and controls.