JP2971530B2 - Developing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a developing device used for a copying machine or the like, and more particularly, to a structure for preventing a developer from scattering in a developing device.

(Prior Art) As is well known, in an image forming apparatus such as a copying machine or a printer, a two-component developer obtained by mixing an electrostatic latent image formed on a photoreceptor with, for example, a toner and a carrier is used. , A visible image is processed, and the visible image is transferred onto copy paper and then fixed to obtain a copy.

One of the above-described image forming apparatuses is a color copying machine that obtains a color image by superimposing images of different colors on the same copy paper. The schematic configuration of the color copying machine will now be described with reference to FIG. .

That is, the color copier includes a scanner unit 21 for reading a document, an image processing unit 22 for electrically processing an image signal output as a digital signal from the scanner unit 21, and each color from the image processing unit 22. And a printer unit 23 for forming an image on copy paper based on the image recording information.

The above-described scanner unit 21 includes a lamp 25 that illuminates the original placed on the original placing table 24 while moving the original in the scanning direction.
A mirror 26, 27, 28 for setting the optical path of the reflected light from the original illuminated by the lamp 25; an image forming lens 29 arranged in this optical path to form an image on the dichroic prism 30; And a light receiver 31 that separates the reflected light from the light and receives the light for each wavelength. Scanner section mentioned above
In 21, in the dichroic prism 30, for example, a light receiver that receives reflected light from a document separated into three kinds of colors of red R, green G, and blue B, that is, image light, receives colors of respective wavelengths, That is, the light is incident on each of the red CCD 31R, the green CCD 31G, and the blue CCD 31B, and is converted into a digital signal in the light receiver.

The above-described digital signal is output to the image processing unit 22,
The same processing unit 22 performs processing necessary for image forming exposure, which will be described later, to record information of each color, for example, black (hereinafter, abbreviated as Bk), yellow (the same, Y), magenta (the same, M), The signals are converted into recording and forming signals of cyan (same as C).

FIG. 4 shows a case where the above four colors of Bk, Y, M, and C are formed, but the number of colors is, of course, not limited to this.

On the other hand, a signal from the image processing unit 22 is input to the printer unit 23, and is used for operation control of the image exposure laser light emitting devices 32Bk, 32C, 32M, and 32Y according to each color.

The above-described printer unit 23 is a part for exposing image light from a document onto a photoreceptor, processing the electrostatic latent image formed by the exposure into a visible image with a developer, and transferring the processed image onto copy paper. It is.

That is, in the illustrated example, the printer unit 23 is provided with four sets of recording devices 33Bk, 33C, 33M, and 33Y arranged side by side.

Since each of the recording devices described above has the same configuration,
For the sake of simplicity, the recording apparatus for C (cyan) will now be described, and the description of the other colors will be omitted.
Note that components having the same function for each color have the same reference numerals, and a reference numeral indicating each color is added to the reference numeral to distinguish the configuration of each color.

That is, in the recording device 33C for C (cyan), the photosensitive member 34C on the drum is arranged in the optical path from the laser light emitting device 32C, and the image forming is performed around the photosensitive member 34C along the rotation direction. A charging device 35C, a developing device 36C, a transfer device 37C, and the like for performing the processing are provided similarly to a known copying machine.

Then, the photosensitive member 34C uniformly charged by the charging device 35C
A latent image of a cyan image is formed by exposure by the laser light emitting device 32C, and the latent image is processed into a visible image by the developing device 36C.

On the other hand, the printer unit 23 is provided with a paper feed unit for copying paper, and from this paper feeding unit, for example, one of two kinds of sizes is selected by a paper feed roller 38. The copy paper is conveyed to the conveyance belt 41 passing through the transfer position of the photoreceptor 34C after its leading end is aligned with the leading end of the image by the registration roller 40.

Then, the copy paper carried on the transport belt 41 and transported to the transfer position of the photoconductor 34C is sequentially transported toward the photoconductors 34Bk, 34C, 34M, and 34Y, each of which has been subjected to visible image processing, and After the visible image of each color is electrostatically transferred by the action of the transfer device 37 provided opposite to the transfer belt 37, the visible image of each color is transferred to the fixing roller 42 from the transfer belt 41 to receive the fixing, and is discharged out of the apparatus by the discharge roller 43. Is discharged. The transfer belt 41 described above electrostatically attracts the copy paper carried thereon,
The belt is conveyed at a moving speed without displacement.

As the above-described developing position, for example, there is a case where a two-component developer in which a resin toner and a magnetic carrier such as iron powder are mixed is used. In the case of this apparatus, a magnet for forming a magnetic brush is incorporated. A magnetic brush is carried on a rotatable developing sleeve, and the toner in the brush is transferred by an electrostatic attraction force from an electrostatic latent image on a photoreceptor. The structure of such a developing device is as follows. , FIG.

That is, a developing device A shown in FIG. 5 includes a developing tank C in which a developing sleeve B is disposed and a replenishing tank D in which replenishing toner is stored.
The replenishment toner is rubbed against the surface of the replenishment roller F located in the vicinity of the developing sleeve B by the supply roller E located at the outlet of the replenishment tank D, and is carried on the surface of the replenishment roller F for development. It is transported toward the sleeve B. The supply roller E, the supply roller F, and the blade G that contacts the surface of the supply roller F to make the supply toner thinner are provided with a supply bias circuit H for the supply toner.
The circuit H corrects the charge amount of the replenishment toner according to the density change of the reference density pattern i formed on the photosensitive member I.

A plurality of magnets including a magnet constituting a developing main pole are attached to a support plate inside the developing sleeve B described above. The brush is brought into contact with the electrostatic latent image on the photosensitive member I.

In FIG. 5, reference numeral J denotes a protrusion that protrudes laterally to form a plane for fixing a lid that closes the supply port.

On the other hand, the developer carried on the surface of the developing sleeve B is exposed from the opening C1 of the developing tank C formed at a position facing the photoconductor I by forming a magnetic brush, and The toner is electrostatically attracted to the electrostatic latent image by contact with the electrostatic latent image.

By the way, in the above-described opening C1 of the developing tank C,
As shown in FIG. 6, a doctor blade C2 is provided on the upstream side in the rotation direction of the developing sleeve B so that a part of the developing tank C projects toward the developing sleeve B, and the layer thickness on the developing sleeve B is reduced. By regulating, the amount of the developer supplied is set.

(Problems to be solved by the invention) However, in the structure of the developing device described above,
As the amount of the developer on the developing sleeve B is regulated, some of the developer is excluded from the surface of the developing sleeve B, and the developer scatters around the opening to the outside from the opening, that is,
Leakage on the photoconductor side may cause soiling of the photoconductor.

Accordingly, as shown in FIG. 6, the developing area where the developer is supplied to the electrostatic latent image on the photoconductor opposite to the photoconductor and the developer is carried even when the developing area is located beside the developing area. Seal member K capable of covering both areas with possible non-developing areas
With the developing sleeve B in a state where a part thereof is in contact with the photosensitive member.
It is conceivable to arrange such that the gap between the inner surface of the developing tank and the inner surface of the developing tank is constant.

However, when such a sealing member K is arranged, it is advantageous to make the gap between the developing sleeve and the inner surface of the developing tank facing the developing sleeve as narrow as possible to prevent scattering due to toner leakage. If this gap is set over the entire area where the developer can be held in the axial direction of the developing sleeve, the magnet is extended in the area where the developer can be held other than the developing area due to the interposition of a structural component such as a bearing. It is difficult to apply the magnetic force, and therefore, the developer not used for development moves on the developing sleeve as it is and stays between the seal member K and the developing sleeve. Sometimes. Therefore, the developer remaining in an area other than the above-described development area is likely to be deposited due to the small influence of the transfer magnetic force on the development sleeve side as described above, and as a result, the deposited developer,
In particular, the solidification of the toner may hinder the rotation of the developing sleeve, or may damage the seal member and cause the toner to scatter.

Therefore, an object of the present invention is to provide the above-described developing device,
In view of the problem in the structure for preventing toner scattering, an object of the present invention is to provide a developing device having a structure capable of preventing stagnation of a developer not used for development and preventing toner scattering and breakage of a seal member. .

(Means for Solving the Problems) In order to achieve this object, the present invention is a developing apparatus for processing a latent image formed on a photoreceptor into a visible image in a developing area, A developing tank containing a developing sleeve mounted on the developing device therein, the developing sleeve having an opening at a position facing the photoconductor, and an upstream side of the developing region in a rotational direction of the developing region in the opening. In the developing region in the axial direction of the developing sleeve, the distal end is extended to the extent that the developer can be exposed, and the developer can be carried on the side of the developing region. In the region, a seal member having a tip formed in a length capable of covering the entire area of the developing sleeve facing the opening and extending along the axial direction of the developing sleeve, the seal member comprising: The above development The structure is characterized in that the thickness of the region capable of supporting the developer located on the side of the region is made thinner than the portion facing the development region.

(Operation) According to the present invention, when the developer that moves to the side of the developing area in the developing sleeve reaches the gap between the developing sleeve surface and the seal member, the gap moves in the moving direction of the developer. Since it is larger than the developing area, it moves without interfering with the seal member.

(Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to Figs. 1 to 3. In FIGS. 1 to 3, it is to be noted that the reference numerals used for the components of the developing device are the same as those used in FIG.

FIG. 1 is a schematic cross-sectional view for explaining a main part of a developing device according to an embodiment of the present invention.

That is, in FIG. 1, the developing tank C containing the developing sleeve B has an opening C1 at a position where the developing sleeve B and the photoconductor I face each other, and an inner surface of the opening C1 has A seal member K1 having a base end attached to the upstream side in the rotation direction of the developing sleeve B, in other words, behind the doctor blade C2 is disposed.

The seal member K1 described above is provided along the axial direction of the developing sleeve B as shown in FIG. 2, and a range corresponding to the developing area in the axial direction (for convenience, this range is referred to as an entrance) is a developing sleeve. The length of the tip is set so that the magnetic brush formed on B can be exposed toward the photoreceptor I, and the range located on the side of the development area (for convenience, this range is referred to as a side portion) is: The length of the leading end is set so as to cover the peripheral surface of the developing sleeve B facing the opening C1. Therefore, the seal member K1 is divided into an entrance seal portion K1A covering the development region and a side seal portion K1B covering the side of the development region.

In the seal member K1, the thickness of the entrance seal portion K1A and the thickness of the side seal K1B are different.

That is, as shown in FIG. 3, the thickness α of the entrance seal portion K1A is set to a certain thickness so as to be able to bend and deform when brought into close contact with the photoreceptor, and that the developer scatters toward the photoreceptor. It is made to be able to prevent by sticking to.
On the other hand, the side seal K
1B, the range extended by the same length as the tip of the entrance seal K1A is made the same thickness α as the entrance seal K1A, and from the position corresponding to the tip of the entrance seal K1A to the tip of the side seal K1B. The thickness β in the range is reduced to increase the distance between the side seal portion K1B and the surface of the developing sleeve B. In other words, the gap between the seal member K1 and the surface of the developing sleeve B is wider in the side seal portion K1B than in the range facing the entrance seal portion K1A.

Since the present embodiment has the above-described structure, the developer carried on the developing sleeve B passes through the doctor blade C2 in the developing tank C and then electrostatically attracts to the photosensitive member I in the developing area. Is done.

On the other hand, on the developing sleeve B facing the side seal portion K1B, the developer that has not contributed to the development is carried on the developing sleeve B as it is and moves to try to interfere with the side seal portion K1B.

However, since the distance between the side seal portion K1B and the surface of the developing sleeve is wider than the developing region, the developer moves without being hindered by the inner surface of the seal member K1.

Therefore, the developer carried on the developing sleeve B in a range opposing the side seal portion K1B is recovered as it is without staying between the developing member B and the seal member K1.

(Effects of the Invention) As described above, according to the present invention, the seal member opposed to the side of the developing area of the developing sleeve on which the developer not contributing to the development is carried is provided such that the distance from the surface of the developing sleeve is equal to that of the developing area. Since the thickness is reduced so as to be larger than that, the interference between the developer remaining on the developing sleeve and having a large residual amount and the seal member can be prevented, and the cause of stagnation can be eliminated. Therefore, it is possible to prevent solidification of the stagnated developer and prevent rotation of the developing sleeve, damage to the surface of the photoconductor, or damage to the seal member.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a main structure of a developing device according to an embodiment of the present invention, FIG. 2 is a perspective view schematically showing a partial arrangement of the structure shown in FIG. FIG. 3 is a perspective view showing a part of the structure shown in FIG. 1 taken out, FIG. 4 is a layout diagram for explaining an example of the image forming apparatus, and FIG. 5 is a view of the apparatus shown in FIG. FIG. 6 is a schematic sectional view showing the structure of the developing device, and FIG. 6 is a sectional view for explaining a part of the structure of the developing device shown in FIG. A: developing device, B: developing sleeve, C: developing tank,
C1 ... Opening, C2 ... Doctor blade, K1 ... Seal member, K1A ... Entrance seal facing the development area, K1B
... Side seal portion facing the side of the development area, α.
Thickness of entrance seal, β ... Thickness of side seal.

Claims (1)

(57) [Claims] 1. A developing device for processing an electrostatic latent image formed on a photosensitive member into a visible image in a developing area, wherein a developing sleeve provided in the developing device is housed inside. A developing tank having an opening formed at a position where the developing sleeve faces the photoreceptor; and a base mounted at the opening in the developing region on the upstream side in the rotation direction of the developing sleeve, and the developing sleeve. In the development region in the axial direction, the tip is extended to a length that allows the developer to be exposed, and in the region where the developer can be carried on the side of the development region, the opening faces the opening. A seal member having a tip extending to a length capable of covering the entire area of the developing sleeve, and a seal member extending over the respective areas, wherein the seal member is capable of carrying a developer positioned on a side of the developing area. A thickness of the region, developing apparatus is characterized by comprising thinner than the thickness of the region opposed to the developing region.