JP3479947B2 - Developing device and image forming apparatus using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for an image forming apparatus such as a copying machine, a facsimile, a printer and the like, and an image forming apparatus using the same, and more specifically to a developer carrying member carrying a developer, A developing device that includes a developer supply member that supplies the developer onto the developer carrier, and develops a latent image formed on the image carrier based on an image signal, and an image forming apparatus using the device. It is about.

[0002]

2. Description of the Related Art Conventionally, a dry developing device used for electrophotography, electrostatic recording, etc. uses a two-component developer containing a toner and a carrier and a one-component developer containing no carrier. There is something to use. The former device is capable of obtaining a relatively stable and good image, but on the other hand, deterioration of the carrier and variation in the mixing ratio of the toner and the carrier are likely to occur, which makes it difficult to maintain and compact the device. There is. On the other hand, in the latter device, a substance corresponding to a carrier is contained in the toner, and when the toner is moved by using a magnetic force, the toner contains a magnetic substance. However, since the magnetic material is opaque, an apparatus using a non-magnetic developer is suitable for color development. In this case,
It is necessary to stably supply the developer to, for example, a developing roller as a developer carrier without using magnetic force. To solve this problem, Japanese Patent Application Laid-Open No. 61-42672 discloses a developing device using a non-magnetic one-component developer, which rotates while contacting the developing roller to supply the developing roller with the developer. A developing device provided with is disclosed.
According to this technique, it is possible to stably form a thin toner layer, which is suitable for development, in which a necessary charge is sufficiently given to the toner and which is uniformly thinned.

Here, when the image ratio is relatively small,
If the developing device is idled without developing, the developer may be deteriorated or scattered, and the image may be disturbed. Therefore, for example, Japanese Patent Laid-Open Nos. 5-134530 and 6-208277 disclose devices for controlling the drive timing of the developing device depending on the presence or absence of an image signal to reduce the idling time of the developing device. ing.

[0004]

However, the consumption amount of the developer supplied onto the developing roller changes depending on the amount of the portion of the image to be formed to which the toner should be attached (hereinafter referred to as the amount of the toner attachment portion). Therefore, the above-mentioned JP-A-5-134
In the apparatus of Japanese Patent Laid-Open No. 530 and JP-A-6-208277, when the image signal is detected and the developing device is driven, the amount of toner supplied onto the developing roller is small relative to the amount of the toner adhering portion. However, the image density is lowered. However, if the amount of toner supplied to the developing roller is large relative to the amount of the toner adhering portion, there is a problem in that toner is scattered downstream of the developing device and scumming on the image carrier occurs. .

The present invention has been made in view of the above problems, and an object of the present invention is to prevent development of toner density and development of a toner capable of preventing toner scatter and background stain of an image carrier. To provide an apparatus and an image forming apparatus using the apparatus.

[0006]

In order to achieve the above object, the invention of claim 1 uses a non-magnetic one-component developer, and a developer carrying member carrying the developer, and the developer. A developing device for developing a latent image formed on the image carrier based on an image signal, comprising a developer supplying member for supplying the developer onto the developer carrier while being in contact with the carrier. hand,
Supply bias voltage applying means for applying a supply bias voltage to the developer supply member, and a developer corresponding to the image signal.
An amount is supplied from the developer supply member to the developer carrier.
To this end, a control means for controlling the supply bias voltage application means is provided.

In this developing device, the supply bias voltage applied to the developer supplying member by the supply bias voltage applying unit is appropriately changed by the control unit in accordance with the image signal, and the developer supplying member changes the supply bias voltage. A developer corresponding to the amount of image is supplied to the developer carrier.

According to a second aspect of the present invention, a non-magnetic one-component developer is used, the developer carrying member carrying the developer, and the developing while the surface is moved in contact with the developer carrying member. A developing device for developing a latent image on an image carrier formed on the basis of an image signal, the developing device including a developer supplying member for supplying the developer onto the agent carrier, the developing device according to the image signal.
The amount of the image developer is supplied from the developer supply member to the developer carrier.
In order to supply the developer, a control means for controlling the moving speed of the developer supply member is provided.

In this developing device, the control means changes the moving speed of the developer supply member in response to the image signal, and the developer supply member develops the developer in accordance with the amount of the image. Supply to the agent carrier.

[0010]

[0011]

According to a third aspect of the present invention, in the image forming apparatus for forming an image by developing the latent image formed on the image bearing member on the basis of the image signal by the developing apparatus, the developing apparatus according to the first or second aspect of the invention. It is characterized by using a developing device.

In this image forming apparatus, the supply bias voltage is supplied by the control means in accordance with the image signal.
Or by changing the moving speed of the developer supplying member, by the developer supplying member supplies the developer according to the amount of the image on the developer carrying member.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter referred to as copying machine) which is an image forming apparatus will be described below. FIG. 1 is a schematic configuration diagram of a copying machine according to this embodiment. The example of this copying machine is an example of a two-color digital copying machine, which has a document reading unit, an image processing unit, and a printer unit, and can use an ADF, a sorter, or the like.

Below the photosensitive drum 11 serving as an image carrier, a sheet conveying path 15 is provided from a sheet feeding device including a sheet feeding cassette 12 and a sheet feeding roller 13 to a sheet discharging tray 14. A registration roller 16, a transfer device 17, a separator 18, and a fixing device 19 are disposed in the middle of the paper transport path 15.

Around the photosensitive drum 11, a first image forming unit 20 for forming a specific color image, for example, a black image on the photosensitive drum 11, and a chromatic color image, for example, a red image, on the photosensitive drum 11. A second image forming unit 21 for forming on top, a cleaning device 22, and a static eliminator 23
And are arranged. The first image forming unit 20 includes a first charger 24 that uniformly charges the photosensitive drum 11, and
The first exposure device 25 and the first developing device 26 are included. The second image forming unit 21 includes a second charger 27,
A self-scanning second exposure device 28 and a second developing device 29 are assembled on a support 30.

In the document reading unit, the color image information of the document 1 placed on the document table is read by the CCD 3 via the optical system 2, and the output signal thereof is read by the image processing unit (IPU) 4. It is divided into a colored portion of the colored toner (hereinafter referred to as the second color) and a portion of the other colors, and converted into an electric image signal. Then, the image signal of the color portion of the second color toner is sent to the second exposure unit 28 and the second development control unit 5 of the printer unit, and the image signals of the other color (hereinafter referred to as the first color) portions are transmitted. It is sent to the first exposure device 25 of the printer unit.

In the printer section, the photosensitive drum 11 is rotated clockwise by the main motor and uniformly charged by the first charger 24 to, for example, -800 V, and then exposed by the first exposure device 25 to 1 An electrostatic latent image of a color image is formed. In this case, the first exposure device 25 drives a laser light source (not shown) to be modulated by a driving circuit with the image signal of the first color from the image processing unit, and deflects the light from this laser light source by the polygon mirror 31 to make the mirror 3
It irradiates while scanning in the main scanning direction (axial direction of the photoconductor drum 11) onto the photoconductor drum 11 via 2. The polygon mirror 31 is rotationally driven by a polygon motor 33. The electrostatic latent image of the image of the first color on the photosensitive drum 11 is supplied to the first developing device 26 by the developing roller 34 to which the developing bias voltage is applied from the developing bias power source. Then, the toner of the first color is developed to form a visible image of the first color.

Next, the photosensitive drum 11 has a second charger 27.
Are charged substantially uniformly by. Then, the photosensitive drum 11
Is exposed by the LED array of the second exposure unit 28 in accordance with the image signal of the second color from the image processing unit, and an electrostatic latent image of the image of the second color is formed. Then, in the second developing device 29, the electrostatic latent image of the image of the second color is developed by the developer of the second color by the developing roller 35 to which the developing bias voltage is applied from the developing bias power source, and the second color is developed. It becomes a visible image of the color. The developing bias voltage applied to the developing roller 35 may be DC voltage, AC voltage, or pulse voltage.

On the other hand, the transfer paper is fed from the paper feed cassette 12 to the registration roller 16 by the paper feed roller 13, and the registration roller 16 sends the transfer paper in synchronization with the visible image on the photosensitive drum 11. The transfer paper is the photosensitive drum 11.
The upper visible image is transferred by the transfer device 17 and separated from the photoconductor drum 11 by the separator 18, and the visible image is fixed by the fixing device 19 and discharged as a copy to the paper discharge receiver 14. After the transfer paper is separated from the photosensitive drum 11, the cleaning device 22 removes the residual toner to remove the static electricity.
By 3, the residual charge is erased.

Next, the second developing device 29 will be described with reference to FIG. The second developing device 29 includes the photosensitive drum 11
A casing having an opening facing the surface, a developing roller 35 as a developer carrying member, a part of which is exposed from the opening and is rotationally driven counterclockwise at a predetermined linear velocity, and the developing roller 35. It is housed in a developer supply roller 36 as a developer supply member that is rotationally driven in the clockwise direction of the arrow while being pressed against the right side portion, and in a hopper part as a developer storing means configured in the right side portion inside the casing. Agitators 37 and 38 that supply non-magnetic one-component developer (hereinafter referred to as toner) to the surface of the developer supply roller 36 and agitate the toner in the hopper, and the photosensitive drum 11 by the rotation of the developing roller 35. And a blade 39 as a developer regulating member that regulates the thickness of the toner layer on the developing roller 35 that is conveyed to the developing area, which is an opposing portion of the developing roller 35, so as to be uniform. Further, the roller 40 is provided coaxially with the developing roller 35, and the roller 40 is brought into contact with the non-image forming area of the photoconductor drum 11, so that a minute gap between the developing roller 35 and the photoconductor 11 is maintained. Is configured.

The developing roller 35 and the agitator 37,
38 is driven to rotate by the main motor, and the second developing device 29
The toner inside is agitated by agitators 37 and 38 and supplied to the developer supply roller 36. Developer supply roller 3
6, a supply roller bias power supply 41 (not shown)
A supply bias voltage is applied so as to form an electric field between the frictionally charged toner and the developing roller 35 so as to receive an electrostatic force from the developer supplying roller 36 side toward the developing roller 35 side. Then, the developer supply roller 36
Supplies toner to the developing roller 35 as the toner rotates, and the toner on the developing roller 35 is regulated to a certain amount by the blade 39 and supplied to the photosensitive drum 11 by the developing roller 35.

FIG. 3 is a control block diagram showing a part of the control in this embodiment. As described above, the document reading unit having the charge coupled device (CCD) 3 reads the document 1 and outputs the image signal to the image processing unit (IPU) 4. The image processing unit (IPU) 4 processes the image signal to
The image signal of the second color and the image signal of the second color are output to the first exposure device 26 and the second exposure device 28 of the printer unit, and the image signal of the second color is output to the second development control unit 5. Output.

In this embodiment, based on the image signal of the second color output from the image processing section, the supply bias voltage corresponding to the area ratio of the image is supplied to the developer supply roller 36.
The second developing control unit 5 controls the supply roller bias power supply 41 so that

FIG. 4 shows the relationship between the area ratio of an image and the amount of toner consumed as a developer for forming the image. The image area ratio and the toner consumption amount are in a proportional relationship, and the toner consumption amount increases as the image area ratio increases. FIG. 5 shows the relationship between the supply bias voltage applied to the developer supply roller 36 and the amount of development of the toner supplied from the development roller 35 onto the photosensitive drum 11. In FIG. 5, the horizontal axis represents the supply potential which is the difference between the supply bias voltage and the developing bias voltage.
As shown in FIG. 5, the developing amount tends to increase as the supply bias voltage becomes higher.

Therefore, when the image area ratio is large and the toner consumption amount is large, the supply bias voltage is increased to increase the developing amount, while when the image area ratio is small and the toner consumption amount is small. If the supply roller bias power supply 41 is controlled so as to reduce the supply bias voltage to reduce the development amount, and the supply bias voltage is changed according to the area ratio of the image, the toner consumption amount is reduced. The amount of developer on the developing roller 35 can be balanced. As a result, the amount of toner supplied to the developing roller is less than the amount of toner required for image formation, resulting in a decrease in image density, or the amount of toner supplied to the developing roller is reduced due to image formation. Since the amount of toner consumed is larger than the amount of toner consumed, toner scattering to the downstream side of the developing device and scumming on the image carrier will not occur.

The second development control section 5 may be configured to change the peripheral speed of the developer supply roller 36 instead of changing the supply bias voltage according to the area ratio of the image. A control block diagram in this case is shown in FIG. 7 shows the relationship between the peripheral speed of the developer supply roller 36 and the amount of development of the toner supplied from the development roller 35 onto the photosensitive drum 11. The horizontal axis of FIG. 7 represents the peripheral speed ratio of the developer supply roller 36 to the developing roller 35. As shown in FIG. 7, the developing amount tends to increase as the peripheral speed of the developer supply roller 36 increases. Therefore, when the image area ratio is large and the toner consumption amount is large, the peripheral speed of the developer supply roller 36 is increased to increase the developing amount, while the image area ratio is small and the toner consumption amount is large. When the amount is small, the developer supply roller 3
In order to reduce the developing amount by lowering the peripheral speed of 6,
By controlling the supply roller motor 42 that drives the developer supply roller 36 to change the peripheral speed of the developer supply roller 36 in accordance with the area ratio of the image, the toner consumption amount and the developing roller 35 are increased. Can be balanced with the amount of developer. As a result, the amount of toner supplied to the developing roller is less than the amount of toner required for image formation, resulting in a decrease in image density, or the amount of toner supplied to the developing roller is reduced due to image formation. Since the amount of toner consumed is larger than the amount of toner consumed, toner scattering to the downstream side of the developing device and scumming on the image carrier will not occur.

The second developing control section 5 as a control means
Thus, the moving speed of the developer supply roller 36 as the developer supply member, that is, the peripheral speed is changed according to the information about the area ratio of the image obtained by the image signal, and the agitator as the developer stirring means. 37,
The peripheral speed of 38 may be changed, and the conveying force of the agitators 37 and 38 may be controlled according to the area ratio of the image. A control block diagram in this case is shown in FIG. The second developing controller 5 controls the supply roller motor 42 according to the area ratio of the image as described above to change the peripheral speed and drives the agitators 37 and 38.
3 is controlled according to the area ratio of the image, and the peripheral speeds of the agitators 37 and 38 are changed. That is, when the image area ratio is large and the toner consumption amount is large, the peripheral speed of the agitators 37 and 38 is increased to increase the conveying force, while when the image area ratio is small and the toner consumption amount is small, The peripheral speed of the agitators 37 and 38 is reduced to weaken the carrying force. This makes it possible to optimize the developer conveying force to the developer supply roller according to the area ratio of the image and prevent the developer from being deteriorated due to the rotation of the agitators 37 and 38. The supply roller motor 42 may be configured to also serve as the agitator motor 43 that drives the agitator. Further, although the illustrated example is an example in which the supply roller motor 42 is controlled according to the area ratio of the image, the supply roller bias power supply 41 is used as described above,
The supply bias voltage applied to the developer supply roller 36 may be controlled. The supply roller motor 42 and the supply roller bias power supply may not be controlled, but only the peripheral speeds of the agitators 37 and 38 may be controlled.

It should be noted that the above-mentioned embodiment is a second embodiment of the present invention.
Although it is an example applied to a color digital copying machine, the present invention is also applicable to a developing device having another structure and using non-magnetic one-component developing, and an image forming apparatus using the same, and The effect of can be obtained. (Hereafter, margin)

[0030]

According to the first and fourth aspects of the invention, the bias voltage applied to the developer supplying member is appropriately changed according to the image signal, and the developer supplying member develops according to the amount of the image. Since the developer is supplied to the developer carrier,
Since the amount of developer supplied on the developer carrier is less than the amount of developer required for image formation, the image density may be reduced, or the amount of developer supplied on the developer carrier. Is greater than the amount of the developer consumed by image formation, the developer is effectively scattered to the downstream of the developing device, and the background stain on the image carrier does not occur.

According to the second and fourth aspects of the invention, the moving speed of the developer supply member is changed according to the image signal, and the developer according to the amount of the image is supplied by the developer supply member. Since it is supplied to the developer carrier, the amount of developer supplied on the developer carrier is less than the amount of developer required for image formation, which leads to a decrease in image density. Since the amount of developer supplied to the body is larger than the amount of developer consumed by image formation, the developer is not scattered to the downstream of the developing device and the background stain on the image carrier does not occur. There is an excellent effect.

[0032]

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an electrophotographic copying machine according to an embodiment.

FIG. 2 is an enlarged view of a second developing device 29 of the copying machine.

FIG. 3 is a control block diagram showing a part of control of the copying machine.

FIG. 4 is an explanatory diagram showing a relationship between an area ratio of an image and a consumption amount of toner as a developer for forming the image.

FIG. 5: Supply potential of the copying machine and developing roller 3
5 is an explanatory view showing the relationship with the amount of development of the toner supplied from No. 5 on the photosensitive drum 11. FIG.

FIG. 6 is a control block diagram of a modified example of control of the copying machine.

7 is an explanatory diagram showing the relationship between the peripheral speed of the developer supply roller 36 and the amount of development of the toner supplied from the development roller 35 onto the photosensitive drum 11. FIG.

FIG. 8 is a control block diagram of another modification of the copying machine.

[Explanation of symbols]

11 Photosensitive drum 29 Second developing device 35 developing roller 36 Developer Supply Roller 37, 38 agitator 5 Second development controller 41 Supply roller bias power supply 42 Supply roller motor 43 Agitator motor

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Claims (3)

(57) [Claims] 1. A non-magnetic one-component developer is used, a developer carrying member carrying the developer, and the developer being supplied to the developer carrying member in a state of being in contact with the developer carrying member. And a developer supplying member for developing a latent image on an image carrier formed based on an image signal, the supplying device applying a supply bias voltage to the developer supplying member. And the amount of developer corresponding to the image signal is set by the developer supply member.
And a control means for controlling the supply bias voltage applying means for supplying the developer to the developer carrier . 2. A non-magnetic one-component developer is used, a developer carrying body carrying the developer, and a developer carrying body moving on the surface while being in contact with the developer carrying body. A developing device for developing a latent image on an image carrier formed on the basis of an image signal, the developing device comprising a developer supplying member for supplying the developer, wherein the amount of developer according to the image signal is the developing amount. Agent supply member
In order to supply the developer carrier to the developer carrier , a developing device is provided with control means for controlling the moving speed of the developer supply member. 3. An image forming apparatus for forming an image by developing a latent image formed on an image bearing member on the basis of an image signal by a developing apparatus, wherein the developing apparatus according to claim 1 or 2 is used as the developing apparatus. An image forming apparatus characterized by the above.