JP2000098719A - Developing device of electrophotographic image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep toner concentration in a developer housing chamber constant in the developing device of an electrophotographic image forming device constituted so that toner is supplies to the developer housing chamber from a toner housing chamber through a toner supply path according to the movement of two-component developer housed in the developer housing chamber. SOLUTION: The photoreceptor 10 side of a mold case 29 is equipped with the developer housing chamber 30 freely rotatably provided with a developing sleeve 33 and set for housing the two-component developer and the back side thereof is provided with the toner housing chamber 31 housing the toner. Then, a partition wall 29b partitioning both chambers 30 and 31 is provided with the toner supply path 40. The chamber 31 has a freely rotatably agitator 35. Besides, the chamber 31 is provided with an opening and closing member 45 opening and closing the path 40. Then, the member 45 is opened and closed according as the agitator 35 is rotated. When the member 45 is closed, the path 40 is blocked so that the powder pressure of the toner in the chamber 31 is prevented from reaching the chamber 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming an image on an image carrier such as a photoreceptor by using an electrophotographic method, such as a copying machine, a printer, a facsimile, or a multifunction machine thereof, and transferring the image. To an electrophotographic image forming apparatus that performs recording on a recording medium such as paper. More specifically, the present invention relates to a developing device that visualizes a latent image formed on an image carrier using a two-component developer (a mixture of a toner and a carrier) in such an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in a developing device of this type, as shown in FIG.
A developer storage chamber 1a for rotatably mounting the developing sleeve 3 for storing a two-component developer is provided on the front side opposite to the above, and a toner storage chamber 1b for storing toner is provided on the rear side thereof. A toner supply path 1d having a narrow width extending from the near side to the back side in the figure along the developing sleeve 3 on the partition wall 1c.
Is provided.

In such a developing device, a distal end of a doctor blade 4 is further provided on the outer periphery of the developing sleeve 3 and an agitator 5 is rotatably provided in the toner storage chamber 1b. The entire apparatus is installed with the toner storage chamber 1b side slightly inclined upward, so that toner can be easily supplied from the toner storage chamber 1b to the developer storage chamber 1a by gravity through the toner supply path 1d.

During development, the developing sleeve 3 is rotated, and the rotation causes the developer to move in the direction indicated by the arrow in FIG. 6 to circulate in the developer accommodating chamber 1a while frictionally charging the toner and the carrier. At the same time, a part of the developer is adsorbed on the outer periphery of the developing sleeve 3 by a magnet built therein, and the developer is thinned by the doctor blade 4. On the other hand, in the toner storage chamber 1b, the agitator 5 is rotated to stir the toner.

In the developer accommodating chamber 1a, a toner is electrostatically adhered from the developer to the surface of the photosensitive member 2 by a bias voltage applied to the developing sleeve 3, and the toner is used to charge the photosensitive member 2
The electrostatic latent image formed thereon is visualized.

When the toner concentration in the developer accommodating chamber 1a decreases, the developer circulates accordingly,
Due to the movement of the developer, the toner from the toner storage chamber 1b gradually passes through the toner supply path 1d to the developer storage chamber 1a.
It is taken in. On the other hand, when the toner concentration increases,
In response, the movement of the developer gradually becomes slower, and the taking in of the toner from the toner storage chamber 1b stops. By the movement of the developer that varies depending on the toner concentration in the developer storage chamber 1a, the toner is replenished from the toner storage chamber 1b to the developer storage chamber 1a so that the toner density in the developer storage chamber 1a is always kept constant. Was.

[0007]

Conventionally, in such a developing device, since the entire device is installed with the toner storage chamber 1b side slightly inclined upward, the toner powder pressure in the toner storage chamber 1b is always constant. This is a state where the toner has been added to the developer storage chamber 1a through the toner supply path 1d. Further, when the agitator 5 rotates during development, the toner powder pressure is also applied to the developer accommodating chamber 1a through the toner supply path 1d by the rotation.

Therefore, conventionally, when the powder pressure of the toner is applied to the developer storage chamber 1a from the toner storage chamber 1b side in this manner, regardless of the movement of the developer in the developer storage chamber 1a at the time of development, The toner may be forcibly taken into the developer accommodating chamber 1a by the toner powder pressure.

Further, in some cases, if the forcible toner intake continues, the toner may aggregate in the toner supply path 1d, and the supply path 1d may be blocked by the aggregated toner, making it impossible to supply toner. .

As a result, the toner is forcibly taken in or the supply of the toner is stopped. As a result, the toner density cannot be kept constant in the developer accommodating chamber 1a. There was a problem that it would decrease.

[0011]

Therefore, according to an embodiment of the present invention, a two-component developer is used as a developer and a developer accommodating chamber 30 is used as in the embodiment described with reference to the following drawings. In the developing device 13 of the electrophotographic image forming apparatus, the toner is supplied from the toner storage chamber 31 to the developer storage chamber 30 through the toner supply path 40 in accordance with the movement of the developer stored in the toner supply path 40. An opening / closing member 45 for opening and closing is provided.

According to a second aspect of the present invention, in the developing device 13 of the electrophotographic image forming apparatus according to the first aspect, for example, as in the embodiment described with reference to the following drawings, the opening and closing member 45 is provided. , Which is opened and closed by an agitator 35 provided in the toner storage chamber 31.

According to a third aspect of the present invention, a two-component developer is used as a developer, and the movement of the developer stored in a developer storage chamber 30 is described in an embodiment described with reference to the following drawings. In the developing device 13 of the electrophotographic image forming apparatus for supplying toner from the toner storage chamber 31 to the developer storage chamber 30 through the toner supply path 40 in accordance with the rotation member 50, The toner supply path 40 is provided to shield the toner supply path 40.

According to a fourth aspect of the present invention, in the developing device 13 of the electrophotographic image forming apparatus according to the third aspect, for example, as in the embodiment described with reference to the following drawings, the rotating member 50 is provided. , And is rotated by toner passing through the toner supply path 40.

According to a fifth aspect of the present invention, in the developing device 13 of the electrophotographic image forming apparatus according to the third aspect, for example, as in the embodiment described with reference to the following drawings, the rotating member 50 is provided. , And is rotated by transmitting the driving force of the driving means.

According to a sixth aspect of the present invention, in the developing device 13 of the electrophotographic image forming apparatus according to the fifth aspect, for example, as in an embodiment described with reference to the following drawings, the rotating member 50 is provided. , And is rotated at a predetermined fixed number of rotations.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a schematic configuration of a copying machine which is an example of an image forming apparatus provided with a developing device according to the present invention.

Reference numeral 10 in the figure denotes a drum-shaped photosensitive member serving as an image carrier. An eraser lamp 12, a developing device 13, a transfer device 14, a cleaning device 15, a static elimination lamp 16, and the like are provided around the photoreceptor 10 in order from the charging device 11 thereon in the rotation direction indicated by the arrow in the drawing. Further, a fixing device 17 is provided on the left side of the cleaning device 15, and an optical reading device 18 is provided above the photoconductor 10. Further, a sheet cassette 19 is detachably mounted below the transfer device 14.

The optical reading device 18 includes optical components such as a light source 20, a lens 21, and a plurality of mirrors 22. Further, a pressure plate 24 for document pressing is provided above the contact glass 23.

When making a copy by using the illustrated copying machine, the original is set on the contact glass 23 by opening the pressure plate 24, the original is pressed by closing the pressure plate 24, and then the copy switch is pressed. Then, while reading the image of the original with the optical reading device 18, the photosensitive member 10 is rotated, and the surface is uniformly charged by the charging device 11 with the rotation, and the surface is irradiated with light from the optical reading device 18. Writing according to the read content is performed, and an electrostatic latent image is formed on the photoconductor 10.

Subsequently, as the photosensitive member 12 rotates, unnecessary charges on the surface of the photosensitive member 12 are erased by the eraser lamp 12, and then, when the photosensitive member 12 passes the position of the developing device 13, toner is adhered by the developing device to form an electrostatic latent image. Are sequentially visualized.

On the other hand, together with the photoreceptor 10, the paper feed roller 2
5, the sheet P, which is a recording medium in the sheet cassette 19, is sent out and abuts against the registration roller pair 26 to be stopped. Then, the registration roller pair 26 is rotated in synchronization with the image on the photoconductor 10, and the paper P is transferred to the photoconductor 1.
0 is sent to the lower side in the figure.

Then, the image on the photoconductor 10 is transferred to the sheet P by the transfer device 14. After the image transfer, the paper P
The sheet is conveyed to the fixing device 17, where the transferred image is fixed, sent out by the sheet discharge roller pair 27, and stacked on the sheet discharge tray 28.

On the other hand, the toner remaining on the surface of the photoreceptor 10 after the image transfer is removed by the cleaning device 15 and the charge is removed by the charge removing lamp 16 to prepare for the next image formation.

By the way, the developing device 13 described above is
As shown in FIG. 3, a mold case 29 is provided along the photosensitive member 10 and the front side of the mold case, that is, the side facing the photosensitive member 10 is opened, and a developer accommodating chamber 30 is provided there. A toner storage chamber 31 is provided.

A two-component developer is stored in the developer storage chamber 30, and a developing sleeve 33 is rotatably provided at a position facing the photoreceptor 10. The developing sleeve 33 incorporates a magnet (not shown), and has a distal end of a doctor blade 34 having a base end supported by an upper portion of the mold case 29 disposed close to the outer periphery.

The toner storage chamber 31 stores toner,
The agitator 35 is provided rotatably about its support shaft 35a. The agitator 35 is formed by a support shaft 35a and a U-shaped frame-like stirring portion 35b that is long in the axial direction.
A toner end detection sensor 36 is provided on the rear wall 29a of the mold case 29 with the detection surface 36a facing the inside of the toner storage chamber 31.

Further, in the mold case 29, a partition wall 29b is provided between the toner accommodating chamber 31 and the developer accommodating chamber 30, and the developing sleeve 3 is provided on the partition wall.
A long and narrow toner supply path 40 is provided along 3. The toner supply path 40 is formed such that its outlet on the side of the developer storage chamber 30 is slightly inclined downward. Then, the toner supply path 40
An opening / closing member 45 for opening and closing the entrance of the toner storage chamber 31 is provided.

As shown in FIG. 3, for example, the opening / closing member 45 is formed by using an elongated plate material and bending the distal end edge 45a slightly, and providing projections 45b outwardly on both end surfaces in the longitudinal direction of the base end edge. Become. Then, the protrusions 45b are rotatably supported by opposed side plates (not shown) provided on both sides of the mold case 29 on the near side and the back side in the figure. Thus, when the developing device 13 is not used, the opening / closing member 45 is in a closed position in which the toner supply path 40 is closed.

In the developing device 13 described above, during use, a developing drive motor (not shown) is driven, the drive is transmitted to rotate the developing sleeve 33, and the rotation causes the developer to move in the direction indicated by the arrow in FIG. While circulating in the developer accommodating chamber 30 while frictionally charging the toner and the carrier, a part of the developer is placed on the outer periphery of the developing sleeve 33.
A so-called magnetic brush is formed by adsorbing the developer with the magnet, and the developer is thinned to a predetermined thickness by the doctor blade.

Further, a bias voltage is applied to the developing sleeve 33, and the toner is electrostatically attached to the surface of the photoconductor 10 from the developer with the bias voltage, and the toner is formed on the photoconductor 10 with the toner. Visualizes the latent image.

On the other hand, during the development, the toner storage chamber 31 transmits the drive of the development drive motor to
5 is rotated clockwise in FIG. 1, and the rotation agitates the toner.

When rotating the agitator 35,
In each case, the tip of the agitating section 35b hits the tip of the opening / closing member 45, and pushes up the opening / closing member to temporarily open the toner supply path 40, during which the toner enters the toner supply path 40. After pushing up the opening / closing member 45, the opening / closing member 45
Return by its own weight and close again. Then, the toner supply passage 40 is closed by the opening / closing member 45, and the toner supply pressure in the toner storage chamber 31 is blocked so as not to reach the toner supply passage 40. In this way, the opening and closing of the opening and closing member 40 is repeated according to the rotation of the agitator 35, so that the toner enters the toner supply path 40 from the toner storage chamber 31 only when the opening and closing member 40 is opened.

On the other hand, in the developer accommodating chamber 30, when the toner is consumed for development and its density decreases, the developer circulates in response to the consumption, and the movement of the developer causes
From the toner storage chamber 31, the toner is gradually taken into the developer storage chamber 30 through the toner supply path 40.

Conversely, when the toner concentration in the developer storage chamber 30 becomes higher, the movement of the developer gradually becomes slower in response to this, and the intake of toner from the toner storage chamber 31 stops. In this manner, the toner is gradually supplied from the toner storage chamber 31 into the developer storage chamber 30 through the toner supply path 40 by the movement of the developer that varies according to the toner concentration in the developer storage chamber 30, and the toner in the toner The concentration is always kept constant.

In the developing device 13 described above, the opening / closing member 45 is always biased to a position where the toner supply passage 40 is closed by using, for example, a spring member.
When opening 0, the opening / closing member 45 is pushed open by the agitator 35 against the spring member, and when closing the toner supply path 40, the opening / closing member 45 may be rotated and closed by the urging force of the spring member. .

Incidentally, in the above-described example, the opening / closing member 45 is used.
Only when is closed, the toner supply passage 40 is closed by the opening / closing member, and the toner powder pressure in the toner storage chamber 31 is reduced.
Try not to reach zero. However, the developing device 13 described above
4, a rotary member 50 is provided in the toner supply path 40 as shown in FIG. 4, for example, and the toner supply path 40 is closed by the rotary member so that the toner powder in the toner storage chamber 31 is removed. The pressure may not always reach the toner supply path 40.

In another example, the rotating member 50 is formed by, for example, radially forming a plurality of elongated blades 50b on the outer periphery of a center support shaft 50a. Then, both ends of the support shaft 50a are rotatably supported by the above-mentioned opposite side plates of the mold case 29, and are disposed so as to shield the toner supply path 40 with the blades 50b.

During development, the toner is supplied from the toner storage chamber 31 to the toner supply path 40 by the rotation of the agitator 35.
Then, the rotating member 50 is rotated by being pushed by the toner passing therethrough, and the rotation further conveys the toner to replenish the inside of the developer accommodating chamber 30.

In the example shown in FIG. 4, the rotating member 50 is rotated by the toner passing through the toner supply path 40. However, the rotating member 50 may be configured to transmit the driving force of the driving unit and rotate.

As shown in FIG. 5, a gear 56 coaxial with the rotary member 50 is engaged with a developing gear 55 coaxial with the developing sleeve 33, for example. The rotation of the rotating member 50 is transmitted through the engagement between the developing gear 55 and the gear 56. In this example, an agitator gear 58 coaxial with the agitator 35 is meshed with a gear 56 via an idler gear 57, and the same driving force of the developing drive motor is applied to the agitator gear 5 during development.
8 to rotate the agitator 35.

When the rotating member 50 is driven to rotate as described above, it is preferable that the rotating speed of the rotating member 50 is set to a constant rotating speed in advance. For example, when a predetermined number of solid image originals having an image area of 100% are copied,
The number of rotations is set in advance so that the density of the copy image remains constant without change.

When the toner enters the toner supply path 40 from the toner storage chamber 31 by the rotation of the agitator 35 during development, the toner is always quantitatively conveyed by the rotating member 50 rotating at a constant speed to store the developer. The toner is supplied into the chamber 30 so that the toner concentration in the chamber 30 is kept constant.

[0044]

According to the first aspect of the present invention, when the opening / closing member closes the toner supply path, the toner pressure from the toner storage chamber is prevented from being applied to the developer storage chamber. During development, the toner is less likely to be taken into the developer storage chamber due to the powder pressure of the toner,
The toner can be taken in by the movement of the developer in the developer accommodating chamber, whereby a high-quality recorded image can be provided while keeping the toner concentration in the developer accommodating chamber constant. Further, by preventing the forced intake of the toner in this way, it is possible to prevent the toner from aggregating in the toner supply path and stopping the toner supply.

According to the second aspect of the present invention,
Since the opening / closing member is opened and closed by an agitator normally provided in the developing device without using a separate driving unit, it is possible to prevent an increase in the number of components and to prevent an increase in cost.

According to the third aspect of the present invention, a rotary member is provided in the toner supply path, the toner is conveyed by the rotation of the toner supply path, and the toner supply path is blocked by the rotary member so that the toner powder pressure is constantly developed. To prevent the toner from entering the developer storage chamber, the toner is not forcibly taken into the developer storage chamber due to the powder pressure of the toner during development, and only by the movement of the developer in the developer storage chamber. The toner can be taken in, whereby the toner density in the developer storage chamber can be kept constant, and a higher quality recorded image can be provided. Further, by completely preventing the forced toner intake, it is possible to reliably prevent the toner from aggregating in the toner supply path and causing the toner supply to be stopped.

According to the fourth aspect of the present invention,
Since the rotating member is configured to be rotated by the toner passing through the toner supply path without using a separate driving unit, it is possible to prevent an increase in the number of parts, thereby preventing an increase in cost.

According to the fifth aspect of the present invention,
Since the rotating member is configured to rotate by transmitting the driving force of the driving unit, the toner can be quantitatively supplied to the developer accommodating chamber by the rotation of the rotating member. The toner density can be stabilized at a constant level.

According to the sixth aspect of the present invention,
In order to allow the rotating member to rotate at a preset constant rotational speed, for example, the rotational speed of the rotating member is set in advance so that the developer accommodating chamber has a constant toner concentration. It is possible to more reliably maintain the room at a constant toner concentration.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a developing device according to the present invention.

FIG. 2 is an overall schematic configuration diagram of a copying machine including the developing device.

FIG. 3 is a perspective view showing the vicinity of a mounting position of an opening / closing member in the developing device.

FIG. 4 is a longitudinal sectional view showing another example of the developing device according to the present invention.

FIG. 5 is a schematic view of a gear train provided in the developing device.

FIG. 6 is a longitudinal sectional view of a conventional developing device.

[Explanation of symbols]

 Reference Signs List 10 photoconductor 13 developing device 30 developer storage chamber 31 toner storage chamber 33 developing sleeve 35 agitator 40 toner supply path 45 opening / closing member 50 rotating member

Claims (6)

[Claims] 1. An electrophotography in which a two-component developer is used as a developer, and toner is supplied from the toner storage chamber to the developer storage chamber through a toner supply path in accordance with the movement of the developer stored in the developer storage chamber. A developing device for an electrophotographic image forming apparatus, comprising: an opening and closing member for opening and closing the toner supply path. 2. The developing device for an electrophotographic image forming apparatus according to claim 1, wherein said opening and closing member is opened and closed by an agitator provided in said toner storage chamber. 3. An electrophotography in which a two-component developer is used as a developer, and toner is supplied from the toner storage chamber to the developer storage chamber through a toner supply path in accordance with the movement of the developer stored in the developer storage chamber. A developing device for an electrophotographic image forming apparatus, wherein a rotating member for transporting toner by rotation is provided in the toner supply path to shield the toner supply path. 4. The developing device for an electrophotographic image forming apparatus according to claim 3, wherein said rotating member is rotated by toner passing through said toner supply path. 5. The developing device for an electrophotographic image forming apparatus according to claim 3, wherein said rotating member is rotated by transmitting a driving force of a driving unit. 6. The developing device for an electrophotographic image forming apparatus according to claim 5, wherein said rotating member is rotated at a preset fixed number of rotations.