JP2003280365A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and inexpensive developing device where a gap between a rotating sleeve and a blade in a developing unit is efficiently and accurately controlled so that it is not changed while the rotating sleeve rotates, and an image forming apparatus. <P>SOLUTION: In the developing device 10 having the rotating sleeve 13 and the blade 11 regulating the thickness of a powder developer layer formed on the sleeve 13 and using powder developer, the blade 11 has an end face 17a opposed to the outer peripheral surface of the sleeve 13 and an abutting member 12 abutting on the outer peripheral surface of the sleeve 17a is provided at both ends of the end face 17a. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device in which a powder developer is used and the thickness of a developer layer is regulated on a developing sleeve, and an image forming apparatus having the developing device (for example, a copying machine, Facsimiles, printers, etc.).

[0002]

2. Description of the Related Art FIG. 6 is a schematic view showing the periphery of an image forming portion such as copying (image forming apparatus). The image forming portion is a portion that forms a predetermined toner image on the recording paper 115 by an electrophotographic process, and has the photosensitive drum 30 having photosensitivity.
1, a charging unit 302, an exposure unit 303, a developing unit 304, a transfer unit 305, a charge removing unit 307, and a cleaner 306 are provided in this order along the rotation direction. The static elimination unit 307 and the cleaner 306 may be arranged in reverse.

The charging unit 302 applies a predetermined potential to the surface of the photosensitive drum 301 by generating corona discharge. The exposure unit 303
Is to selectively attenuate the surface potential of the photosensitive drum 301 by irradiating light corresponding to a desired image to form an electrostatic latent image. The developing unit 304 is
The electrostatic latent image formed on the surface of the photoconductor drum 301 is developed with toner to form a toner image. The transfer unit 305 transfers the toner image formed on the photosensitive drum 301 onto the recording paper 115. The charge eliminating unit 307 is for eliminating the surface charge of the photoconductor drum 301 by the lamp light. The cleaner 306 is composed of a fur brush 316 and a rubber blade 326, and removes toner and its additives remaining on the surface of the photosensitive drum 301. The cleaner 306 in the illustrated example is a fur brush 316.
And a rubber blade 326, but may be a cleaner 306 having only one.

The recording paper 115 to which the toner image has been transferred in the image forming section is heated and pressed by the heating roller 401 and the pressure roller 402 to fix the toner image (fixing section), and then the discharge roller ( The sheet is discharged onto the sheet discharge tray (not shown).

FIG. 7 is a sectional view showing the conventional developing unit (developing device) 304, which is shown together with the photosensitive drum 301. Housing 3 of developing unit 304
A magnetic one-component developer (toner) (not shown) is provided inside 93.
And a stirring roller 3 for stirring the toner.
24, and a developing roller 344 for transferring the toner to the surface of the photosensitive drum 301 are axially supported by the housing 393.

The developing roller 344 comprises a rotating sleeve 341 covering the roller surface and a roller-shaped magnet 342 provided inside the roller. The rotating sleeve 341 rotates while the magnet 342 is fixed. Has become. A magnetic blade 394 is provided to face the developing roller 344, and is fixed and attached to the housing 393 with screws or the like.

Regarding the magnetic pole arrangement of the magnet 342, for example, an S pole (blade pole S1) is arranged at a position facing the magnetic blade 394, and an N pole (developing pole N1) is arranged at a position facing the photosensitive drum 301. An example is a four-pole structure in which the S pole (S2) is arranged on the downstream side of the developing pole N1 in the rotating sleeve rotation direction, and the N pole (N2) is arranged on the further downstream side.

Next, a developing method using the developing unit 304 will be described. The toner in the developing unit 304 is charged to a predetermined polarity by friction with the rotary sleeve 341, and the charged toner is attached to the rotary sleeve 341 and conveyed. The toner layer thickly formed on the rotating sleeve 341 is divided into two at the intermediate position between the rotating sleeve and the blade when passing through the magnetic blade 394, and the toner near the magnetic blade 394 is divided into two parts. The toner that is fixed to the rotating sleeve 341 and is fixed to the rotating sleeve 341 is attracted to the rotating sleeve 341 by the magnetic attraction force and is separated from the magnetic blade 394.
Head to.

The thin toner layer that has come to the position facing the photoconductor drum 301 jumps to the electrostatic latent image portion formed on the photoconductor drum 301, and forms an image by toner on the surface of the photoconductor drum 301.

[0010]

However, in the toner coating method on the rotary sleeve 341 as in the above-mentioned conventional example, the magnetic blade 394 attached to the housing 393 and the rotary shaft rotatably supported by the housing 393 are also provided. If the gap between the rotating sleeve and the blade of the sleeve 341 is not accurately managed, the background fog is likely to occur when the gap is large, and the toner is easily deteriorated when the gap is small. Therefore, in the assembly process of the developing unit 304, adjustment using a gap gauge or the like and fixing of screws are necessary, but it takes time to adjust and fix, and the skill of the operator is required, which is inefficient. Met. Further, in the case where the gap changes during the rotation of the rotary sleeve 341, the above-described problem periodically occurs as the rotary sleeve 341 rotates. In order to prevent this, it is necessary to selectively use the rotating sleeve 341 with less eccentricity and to make the housing 393 strong so as not to vibrate.

Therefore, in the present invention, the gap between the rotary sleeve and the blade in the developing unit is efficiently and accurately controlled, and the gap does not change during the rotation of the rotary sleeve, which is compact and inexpensive. , And an image forming apparatus.

[0012]

A developing device according to the present invention according to claim 1 has a rotary sleeve and a powder for controlling the thickness of a powder developer layer formed on the rotary sleeve. In a developing device using a developer, the blade has an end surface facing the outer peripheral surface of the rotating sleeve, and contact members that contact the outer peripheral surface of the rotating sleeve are provided at both ends of the end surface. It has a feature.

According to the above invention, since the gap between the outer peripheral surface of the rotary sleeve and the end surface of the blade is directly set by the abutting members provided at both ends of the end surface of the blade,
The gap between the rotating sleeve and the blade can be set in a short time and is accurately managed, and the gap does not change during the rotation of the rotating sleeve. In addition, a compact and inexpensive structure is possible.

According to a second aspect of the present invention, in the developing device according to the first aspect, the abutting member is a sheet member made of a low friction material having a predetermined thickness. According to the above invention, the contact member is formed of a sheet member of a low friction material such as fluororesin having a predetermined thickness,
An inexpensive configuration is possible. Further, since the rotary sleeve abuts against the sheet member made of the low friction material and slides and rotates,
Rotation is light and smooth, and damage due to high friction of the sheet member is avoided.

According to a third aspect of the present invention, in the developing device according to the first or second aspect, the blade is biased toward the rotary sleeve with a predetermined pressure. According to the present invention described above, for example, this blade has a biasing pressure of 0.2 to 1.4 g / m 2 per length for forming a thin layer of powder developer.
Energize at a predetermined pressure of m. If the biasing pressure is higher than this, the sheet member is crushed and the gap between the rotating sleeve and the blade becomes small. If the urging pressure is smaller than this, the gap is widened by the powder developer or the blade vibrates.

According to a fourth aspect of the present invention, in the developing device according to the third aspect, the rotary sleeve contains a magnet, and the blade made of a magnetic material has a magnetic attraction force on the rotary sleeve side. Is urged by. According to the present invention described above, since the blade is biased by the magnetic attraction force, no special biasing means is required, and a more compact and inexpensive developing device can be realized.

According to a fifth aspect of the invention, in the developing device according to any one of the first to fourth aspects, the powder developer is a magnetic one-component developer. The inventions of claims 1 to 4 are particularly effective in magnetic one-component development in which the rotating sleeve-blade gap is set small.

According to a fifth aspect of the present invention, the image forming apparatus includes the developing device according to any one of the first to fifth aspects, and the electrostatic latent image formed on the photoconductor is developed by the developing device. It is the invention of the device. According to the above invention, since the gap between the outer peripheral surface of the rotating sleeve and the end surface of the blade is directly set by the abutting members provided at both end portions of the end surface of the blade, the rotating sleeve-blade gap is shortened in a short time. Not only can it be set, but it can also be managed accurately, and the gap does not change during rotation of the rotating sleeve.
In addition, a compact and inexpensive structure is possible.

Further, since the abutting member is made of a sheet member of a low friction material such as fluororesin having a predetermined thickness, an inexpensive structure can be realized. Further, since the rotary sleeve abuts against the sheet member made of the low friction material and slides and rotates, the rotation is light and smooth, and the sheet member is prevented from being damaged due to high friction. Further, for example, when the blade presses with a predetermined pressure of 0.2 to 1.4 g / mm as a pressing force per length for forming a thin layer of the powder developer, the sheet member is crushed and the rotary sleeve- It is possible to prevent the gap between the blades from becoming small, the gap from being spread by the powder developer, and the vibration from occurring in the blades.

Further, when the blade is pressed by the magnetic attraction force, no special pressing means is required, and a more compact and inexpensive developing device can be realized. Also, these are
It is particularly effective in magnetic one-component development in which the rotating sleeve-blade gap is set small.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an example of a copying machine (image forming apparatus) according to an embodiment of the present invention will be described. FIG. 1 is a schematic diagram showing a schematic configuration of the copying machine. The same components as those in FIG. 5 are designated by the same reference numerals to avoid redundant description.

The copying machine 60 includes a paper feeding section 200 arranged at the bottom of the copying machine main body, an image forming section 300 arranged above the paper feeding section 200, and more than the image forming section 300. The fixing unit 400 disposed on the discharge side and the fixing unit 4
00, and an image reading unit 500 provided above the main body of the copying machine. The paper feeding unit 200, the image forming unit 300, the fixing unit 400, and the ejection unit. Paper transport unit 100 connecting the units 600
Is equipped with.

The image forming section 300 forms a predetermined toner image on a sheet by the electrophotographic process as described above, and the photosensitive drum 301 rotatably supported.
Around the photosensitive drum 301 along the rotation direction (arrow A), the charging unit 302 and the exposure unit 3
03, developing unit (developing device) 10, transfer unit 3
05, the cleaner 306 is provided. The developing unit 10 develops the electrostatic latent image with toner to form a toner image on the surface of the photosensitive drum 301.

The fixing unit 400 is the image forming unit 30.
No. 0, which is arranged on the downstream side in the paper conveyance direction, and on which the toner image is transferred in the image forming unit 300 is nipped by a pair of rollers (a heating roller 401 and a pressure roller 402) and heated, and the toner is transferred onto the paper. It fixes the image.

The image reading section 500 irradiates a document placed on the contact glass with light from an exposure lamp and guides the reflected light to a photoelectric conversion section via a reflecting mirror.
The image information of the original is read.

The paper feeding section 200 comprises a plurality of paper feeding cassettes 201, 202 and 221. The paper feed cassette 221 is a bypass tray for replenishing paper from the side of the copying machine, and can be closed by a lid 222.

Each of the paper feed cassettes 201, 202,
A sheet conveyance path 110 is connected to the sheet 221, and the sheet conveyance path 110 faces the image forming unit 300, and further, the fixing unit 40.
It goes toward the discharge part 600 through 0. Note that the paper transport path 110 constitutes the paper transport unit 100. Further, the paper for which copying has been completed is discharged onto the discharge tray 610 from the discharge roller 605 of the discharge unit 600.

As can be seen from FIG. 1, the copying machine 60 is a vertical conveyance type, and the entire copying machine is compact. As the developing unit 10, the developing roller 14 is located above,
The toner storage portion 354 is shaped to be located below the developing roller 14.

Next, a developing unit (developing device) 10 according to an embodiment of the present invention used in the above copying machine will be described. FIG. 2 is a sectional view showing the developing unit 10. A magnetic one-component developer (toner) (not shown) is stored in the toner storage portion 354 of the developing unit 10, and two stirring rollers 314 that stir the toner.
324 is provided. In addition, toner is applied to the photosensitive drum
The developing roller 14 for shifting to the surface 01 is provided above the toner storage portion 354.

The developing roller 14 is a cylindrical rotary sleeve 13 made of a non-magnetic material such as aluminum.
And a fixed magnet 15 contained in the rotary sleeve 13, and the rotary sleeve 13 rotates around the fixed magnet 15 with the position of the magnet 15 fixed. Magnet 1 in this rotating sleeve 13
5 is the same as the conventional one, the S pole (blade pole S1) and the photosensitive drum 3 are provided at a position facing a toner layer thickness regulating member 16 described later
The N pole (developing pole N1) is arranged at a position facing 01, and the S pole (S
2) The N pole (N2) is arranged further downstream.

The blade 11 may be provided so as to face the rotating sleeve 13 (developing roller 14), and a magnet may be further attached to the blade 11 on the upstream side of the blade 11 in the rotating sleeve rotating direction.

FIG. 3A is a partially enlarged sectional view showing the developing roller 14 and the blade 11, and FIG. 3B is a further enlarged sectional view of the portion between the blade and the rotary sleeve. The same components as those in FIG. 2 are designated by the same reference numerals to avoid redundant description.

The blade 11 is a magnetic plate member (eg, magnetic stainless steel, specifically SUS340 or SU).
S430 etc., and its rotating sleeve 1
A thin edge portion 17 having an end surface 17a is formed at a portion facing the third edge portion 3. The end surface 17a of the thin edge portion has a predetermined gap W1 (for example, 0.
2 to 0.4 mm) is opened to extend in parallel with the axial direction of the rotating sleeve. End face 17 of the thin edge portion
The thickness T2 at a is, for example, 0.4 mm (preferred thickness T2
Is 0.4 to 0.8 mm), and by making T2 small in this way, the width of the end face 17a becomes small and the stress given to the developer passing therethrough becomes short, so that the development The agent is less likely to deteriorate. However, if it is too small, the strength will be insufficient.

The protrusion length L1 of the thin edge portion 17 is, for example, 0.5 mm (a preferable protrusion length L1 range is 0.3 to 0.8 mm). The thickness T3 of the trunk portion 18 of the blade 11 is, for example, 2 mm, and holds the position of the thin edge portion 17 firmly without bending. This executive 18
The transition portion 19 from the thin edge portion 17 to the thin edge portion 17 is gradually inclined so as to be inclined. By doing so, the magnetic lines of force from the blade pole S1 can be concentrated on the narrow end surface 17a, whereby a stable thin layer of developer is maintained between the rotating sleeve 13 and the end surface 17a of the blade 11. It

Next, the blade 11 which is a feature of the present invention
The supporting method of 1 will be described with reference to FIGS. Figure 4
Is a partial perspective view near one end of the developing roller 14,
FIG. 5 is a cross-sectional view taken along the line BB in FIG.

In FIG. 4, the developing roller 14 has a shaft 34.
Both ends are axially supported by the housing 393 of the developing unit by the bearing portion 311 that supports the developing unit 3. Also, blade 1
The position of No. 1 in the thickness T3 direction is regulated by the support slits 16 provided in the housing 393 near both ends of the developing roller. When the blade 11 is assembled in the developing unit 10, both ends of the blade 11 are smoothly inserted from above the supporting slit 16 in FIG. 4 toward the developing roller 14 along the slit without rattling. Since the blade 11 is made of a magnetic material, it is urged toward the rotary sleeve 13 by being attracted by the magnetic force of the blade pole S1. The supporting mechanism of the blade 11 may not be the slit as described above. The developing roller 1 can support both sides of the blade 11 in the thickness direction.
As long as it can slide smoothly in the direction of 4 without play, it may be sandwiched between ribs arranged on both sides of the blade 11 in the thickness direction. Further, the ribs may be arranged so as not to face each other.

Further, as shown in FIG. 5, the thin edge portion 17 of the blade 11 covers the end surface 17a at a position opposite to a portion (region D in FIG. 4) of both ends of the rotary sleeve 13 where the toner does not adhere. As described above, a thin sheet member 12 made of fluororesin (for example, 2 mm × 10 mm, thickness 0.3 mm)
However, for example, a double-sided tape is attached so as to cross the end surface 17a in the width direction. The end surface 17a of the blade 11 is
It is in contact with the rotary sleeve 13 via the sheet member 12. That is, the gap between the end surface 17a and the outer peripheral surface of the rotary sleeve 13 is directly set by the sheet members 12 provided at both ends of the end surface 17a of the blade 11. As a result, the gap between the rotary sleeve and the blade is accurately managed, and the gap does not change during the rotation of the rotary sleeve. Further, by using such a sheet member as the contact member, highly accurate gap management can be performed with an inexpensive material.

The outer peripheral surface of the rotary sleeve 13 is roughened by sandblasting or the like so that the toner can be easily conveyed by the rotation of the sleeve 13 on the surface of the portion C on which the toner is placed, but the portion D on which the toner is not placed is provided. The surface of is not roughened and has a smooth surface. Since the sheet member 12 made of a low-friction material having a predetermined thickness such as a fluororesin is brought into contact with this portion, when the rotating sleeve is rotated, sliding rotation with the rotating sleeve is light and smooth, and the sheet member is high. It is possible to avoid damage due to friction.

Further, the blade 11 is urged to the rotary sleeve side by a predetermined pressure by the magnetic attraction force of the blade pole S1 along the support slit 16. Since the blade is biased by the magnetic attraction force, no special biasing means is required. Further, by attaching a plate-shaped magnet to the blade 11, the magnetic attraction force can be adjusted. For example,
It is suitable that the blade is biased at a predetermined pressure of 0.2 to 1.4 g / mm as a biasing pressure per length for forming a thin layer of powder developer. If the biasing pressure is higher than this, the sheet member is crushed and the gap between the rotating sleeve and the blade becomes small. If the urging pressure is smaller than this, the gap is widened by the powder developer or the blade vibrates.

Next, a method of setting the rotary sleeve-blade gap by the sheet member 12 will be described. By adhering the sheet member 12 to the blade 11 and inserting the blade 11 into the support slit 16, the blade 11 is urged by the magnetic attraction force of the blade pole S1 of the developing roller 14, and the blade 11 causes the sheet member 12 to rotate. The both end portions are contacted with a predetermined urging pressure. After that, by the initial rotation of the rotary sleeve 13 for about 1 minute, the seat member 12 fits in the contact portion of the rotary sleeve 13, and thereafter, the seat member 1
2 can be continued to rotate with low sliding friction without being scraped or peeled off. As described above, not only can the setting be performed in a short time, but also the accuracy can be controlled, and the gap does not change during the rotation of the rotary sleeve.

The present invention is simple and highly accurate in the gap between the rotating sleeve and the blade in the non-magnetic one-component developing method and the two-component developing method in addition to the magnetic one-component developing method as described in the above embodiment. The method is sufficiently effective as a method with high stability and high stability, and is effective within the scope of the claims without being limited to the above embodiment.

[0042]

As described above, the developing device according to the present invention according to claim 1 has the rotating sleeve and the blade for regulating the thickness of the powder developer layer formed on the rotating sleeve. In the developing device using the powder developer, the blade has an end surface facing the outer peripheral surface of the rotating sleeve, and contact members that contact the outer peripheral surface of the rotating sleeve are provided at both ends of the end surface. Therefore, since the gap between the outer peripheral surface of the rotary sleeve and the end surface of the blade is directly set by the abutting members provided at both ends of the end surface of the blade, the gap between the rotary sleeve and the blade can be set in a short time and the accuracy can be improved. It is well controlled and the gap does not change during rotation of the rotating sleeve.
In addition, a compact and inexpensive structure is possible.

A developing device according to a second aspect of the present invention is the developing device according to the first aspect, wherein the abutting member is a sheet member of a low friction material such as fluororesin having a predetermined thickness. And an inexpensive configuration is possible. Also,
Since the rotary sleeve abuts against the sheet member made of the low friction material and slides and rotates, the rotation is light and smooth, and the sheet member is prevented from being damaged due to high friction.

A developing device according to a third aspect of the present invention is the developing device according to the first or second aspect, wherein the blade is biased toward the rotary sleeve with a predetermined pressure.
For example, this blade urges a pressure of 0.2 to 1.4 g / mm as a predetermined proper pressure as the urging pressure per length for forming a thin layer of the powder developer. If the biasing pressure is higher than this, the sheet member is crushed and the gap between the rotating sleeve and the blade becomes small. If the urging pressure is smaller than this, the gap is widened by the powder developer or the blade vibrates.

A developing device according to a fourth aspect of the present invention is the developing device according to the third aspect, wherein the rotary sleeve contains a magnet, and the blade made of a magnetic material is on the rotary sleeve side. Since it is urged by the magnetic attraction force, no special urging means is required, and a more compact and inexpensive developing device can be realized.

A developing device according to a fifth aspect of the present invention is the developing device according to any one of the first to fourth aspects, wherein the powder developer is a magnetic one-component developer and the gap between the rotating sleeve and the blade is small. It is particularly effective in the set magnetic one-component developing method.

An image forming apparatus according to a sixth aspect of the present invention comprises the developing device according to any one of the first to fifth aspects,
The developing device develops the electrostatic latent image formed on the photoconductor. Thereby, since the gap between the outer peripheral surface of the rotating sleeve and the blade end surface is directly set by the abutting members provided at both end surfaces of the blade,
The gap between the rotating sleeve and the blade can be set in a short time and is accurately managed, and the gap does not change during the rotation of the rotating sleeve. In addition, a compact and inexpensive structure is possible.

Further, since the abutting member is made of a sheet member having a predetermined thickness and made of a low friction material such as fluororesin, an inexpensive construction is possible. Further, since the rotary sleeve abuts against the sheet member made of the low friction material and slides and rotates, the rotation is light and smooth, and the sheet member is prevented from being damaged due to high friction. Further, for example, when the blade presses with a predetermined pressure of 0.2 to 1.4 g / mm as a pressing force per length for forming a thin layer of the powder developer, the sheet member is crushed and the rotary sleeve- It is possible to prevent the gap between the blades from becoming small, the gap from being spread by the powder developer, and the vibration from occurring in the blades.

Further, when the blade is pressed by the magnetic attraction force, no special pressing means is required, and a more compact and inexpensive developing device can be realized. Also, these are
It is particularly effective in magnetic one-component development in which the rotating sleeve-blade gap is set small.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of an example of a copying machine (image forming apparatus) according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a developing unit (developing device) according to an embodiment of the present invention.

FIG. 3A is an enlarged cross-sectional view showing a portion of a developing roller and a toner layer thickness regulating member, and FIG. 3B is a further enlarged cross-sectional view of a portion between a blade and a rotary sleeve.

FIG. 4 is a partial perspective view near one end of a developing roller 14.

5 is a cross-sectional view taken along the line BB in FIG.

FIG. 6 is a schematic diagram showing the periphery of an image forming unit for copying or the like.

FIG. 7 is a sectional view showing a conventional developing unit (developing device).

[Explanation of symbols]

10 Development unit (developing device) 11 blade 12 Sheet member (contact member) 13 rotating sleeve 14 Developing roller 15 fixed magnet 17 Thin Edge 17a end face 60 Copier (image forming device) S1 blade pole

Continued front page    F term (reference) 2H031 AC02 AC02 AC08 AC31 AC34 BA03                       BB01                 2H077 AB01 AB18 AC04 AD06 AD12                       AD13 AD18 AD23 AD36 AE04                       EA13

Claims (6)

[Claims] 1. A developing device using a powder developer, comprising: a rotary sleeve; and a blade for regulating the thickness of a powder developer layer formed on the rotary sleeve, wherein the blade is the outer peripheral surface of the rotary sleeve. And a contact member for contacting the outer peripheral surface of the rotary sleeve is provided at both ends of the end surface. 2. The developing device according to claim 1, wherein the contact member is a sheet member made of a low-friction material having a predetermined thickness. 3. The developing device according to claim 1, wherein the blade is biased toward the rotary sleeve with a predetermined pressure. 4. The developing device according to claim 3, wherein the rotary sleeve contains a magnet, and the blade made of a magnetic material is biased toward the rotary sleeve by a magnetic attraction force. 5. The powder developer is a magnetic one-component developer,
The developing device according to claim 1. 6. An image forming apparatus comprising the developing device according to claim 1, wherein the developing device develops an electrostatic latent image formed on a photoconductor. .