JPH11174833A - Developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the durability of a developing device, to reduce the burden of a user by prolonging the supplying interval of developer, to suppress the deterioration of image quality outputted after the developer is supplied and to reduce the cost of a developer supply system. SOLUTION: This developing device is provided with a rigid developer layer forming means 4a and an elastic developer layer forming means 4c as the developer layer forming means with respect to a developer carrying/feeding means 2. The forming means 4a is not made in contact with the carrying/feeding means 2 and the forming means 4c is made away from the carrying/feeding means 2 in a term other than the fixed term after the developer is supplied to the inside of a developing container 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device and an image forming apparatus.

More specifically, a developer container for accommodating a powder developer, a developer carrying / transporting means for carrying and transporting the developer in the developing container on the surface, and a surface of the developer carrying / transporting means It has a developer layer forming means for forming a thin layer of developer thereon, and the developer layer carried and formed on the surface of the developer carrying / transporting means enables the electrophotographic photosensitive member, the electrostatic recording dielectric, etc. And a developing device for developing a latent image formed by an appropriate latent image forming means on the image bearing means. The invention also relates to an image forming apparatus provided with the developing device.

[0003]

2. Description of the Related Art FIG. 13 shows a schematic configuration of an example of the above-described developing device. FIG. 14 is a partially enlarged model view thereof.

The developing device A of this embodiment is a developing device using a one-component magnetic / insulating developer (hereinafter, referred to as a toner) as a powder developer. The electrostatic latent image formed is developed as a toner image.

The image bearing means B is a rotating drum type electrophotographic photosensitive member in this embodiment. The photoreceptor B is driven to rotate at a predetermined peripheral speed (process speed) in the clockwise direction of the arrow, and an electrostatic latent image corresponding to the target image information is formed on its outer peripheral surface by a well-known electrophotographic process means (not shown). An image is formed.

In the developing device A, reference numeral 1 denotes a developing container in which a toner t is stored.

Reference numeral 2 denotes a developing sleeve made of a non-magnetic material as a developer carrying / transporting means. The developing sleeve 2 is rotatably supported between a rear side wall and a front side wall of the developing container 1 via a bearing. is there. The front side of the developing sleeve 2 is exposed to the outside,
The rear side faces the inside of the developing container 1.

Reference numeral 3 denotes a magnet roller inserted into the developing sleeve 2 as a magnetic field generating means. The magnet roller 3 is fixed non-rotatably, and the developing sleeve 2 is driven to rotate around the fixed magnet roller 3 by a driving system (not shown) at a predetermined peripheral speed in a counterclockwise direction indicated by an arrow.

Reference numeral 4a denotes a blade member as a developer layer forming means for forming a thin layer of toner on the surface of the developing sleeve 2. The developer layer forming means 4a in this example is a magnetic or non-magnetic rigid blade member, and as shown in FIG.
The lower side thereof is disposed in a state of being in non-contact proximity to the developing sleeve 2 with a predetermined small gap β, and the gap β
In some cases, the thickness of the magnetic attraction layer of the toner on the developing sleeve 2 is regulated as a predetermined thin layer.

Reference numerals 5 and 6 denote first and second toner stirring / conveying members disposed in the developing container 1, respectively, which are rotationally driven at a predetermined speed in a clockwise direction indicated by an arrow by a drive system (not shown). The toner in the developing container 1 is stirred by the rotation of the first and second toner stirring and conveying members 5 and 6, conveyed in the direction of the developing sleeve, and supplied to the rear side of the developing sleeve 2.

The developing device A is arranged such that the developing sleeve 2 is close to the photosensitive member B in a non-contact manner with a predetermined small gap α.

Reference numeral E denotes a developing bias application power source for applying a predetermined developing bias to the developing sleeve 2.

A part of the toner t supplied to the rear side of the developing sleeve 2 is applied to the surface of the developing sleeve 2 by the magnetic field of the magnetic pole S2 of the developer roller of the magnet roller 3 inside the developing sleeve. And is transported as the developing sleeve 2 rotates.

The magnetically attracted layer of the toner is conveyed to an opposing gap β between the blade member 4a as a developer layer forming means and the developing sleeve 2, and the layer thickness is regulated by the gap β and the magnetic field of the magnetic pole N1. The developing sleeve 2 is coated as a predetermined thin layer.

The thin layer of toner is used for the subsequent developing sleeve 2.
, The toner is transported to a developing site a, which is a portion of the photoconductor B and the developing sleeve 2 that are in close proximity to each other, under the action of the magnetic field of the developing magnetic pole S1 and the developing bias. Then, the electrostatic latent image on the surface of the rotating photoconductor B is selectively developed as a toner image by selectively shifting to the photoconductor B side corresponding to the electrostatic latent image.

The toner on the developing sleeve 2 that has not been subjected to the development is returned and transported into the developing container 1 by the subsequent rotation of the developing sleeve 2. N2 is a developer carrying magnetic pole.

The toner image on the surface of the rotating photoreceptor B is transferred to a recording material by a transfer means (not shown), and the recording material is discharged as an image formed matter via a fixing means (not shown).

After the transfer of the toner image to the recording material, the surface of the photosensitive member B is cleaned by the cleaning means and is repeatedly used for image formation.

Reference numeral 7 denotes a developer amount detecting means provided near the developing sleeve 2 in the developing container 1. 8 is a developing container 1
Is a replenishing toner hopper or a replenishing toner bin. The toner t in the developing container 1 is gradually consumed and reduced in the development of the electrostatic latent image on the photoconductor B. The amount of toner in the developing container 1 is detected by the developer amount detecting means 7, and the developer amount detection information is input to a control unit (not shown). The control unit is
When the toner amount in the developing container 1 decreases to a predetermined allowable lower limit, a warning to that effect is issued. In response to the warning, the user replenishes the developing container 1 with the replenishing toner. Alternatively, an appropriate amount of toner is automatically supplied at an appropriate time. The toner replenished in the developing container 1 includes first and second toner stirring and rotating members 5.
The toner is stirred by the rotation of 6, is conveyed in the direction of the developing sleeve 2, and is supplied to the rear side of the developing sleeve 2.

In such a developing apparatus A, as a developer layer forming means for forming a thin developer layer having a predetermined thickness on the surface of the developing sleeve 2 as a developer carrying / transporting means, the above-mentioned FIG. .. of a magnetic or non-magnetic rigid blade member 4a, as shown in FIG. 14, arranged so that the lower side thereof is in non-contact and close proximity to the developing sleeve 2 with a predetermined small gap β. In addition, those shown in FIGS. 15 to 17 are also used.

FIG. 15: A rigid roller 4b (cylindrical or columnar member) is used as a developer layer forming means, and the rigid roller 4b is brought into non-contact with the developing sleeve 2 at a predetermined small gap β. The rigid roller 4b is arranged in a state where the rigid rollers 4b are brought close to each other, and is driven to rotate at a predetermined peripheral speed in a counterclockwise direction indicated by an arrow.

That is, the toner layer carried as a magnetic attraction layer on the surface of the developing sleeve 2 by the magnetic field of the developer pumping magnetic pole S2 causes the rigid roller 4 to rotate as the developing sleeve 2 rotates.
b and the developing sleeve 2 are conveyed to each other, and the layer thickness is regulated by passing through the gap β to coat the developing sleeve 2 as a predetermined thin layer.

FIG. 16: An elastic plate-like member 4c such as a rubber plate is used as a developer layer forming means, and one long side of the elastic plate-like member 4c is clamped by a clamp member 9 to be fixed and held. The surface is placed in contact with the surface of the developing sleeve 2 with an appropriate pressure F (pressure contact force per unit length along the axis of the developing sleeve 2) by belly contact.

That is, the toner layer carried as a magnetic attraction layer on the surface of the developing sleeve 2 by the magnetic field of the developer pumping magnetic pole S2 causes the contact portion between the elastic plate member 4c and the developing sleeve 2 by the rotation of the developing sleeve 2. Is transported through the contact portion, and the layer thickness is regulated by coating the developing sleeve 2 as a predetermined thin layer.

Reference numeral 10 denotes plastic or the like, which is provided as a developer layer forming means so as to cover the surface (upper surface, rear surface) of the elastic plate member 4c opposite to the surface (lower surface, upper surface) on the developing sleeve 2 side. The formed developer flow control member prevents the developer from accumulating and staying on the upper surface of the elastic plate-shaped member 4c and pressing the elastic plate-shaped member 4c.

FIG. 17: An elastic roller 4d (cylindrical or columnar member) is used as a developer layer forming means, and the elastic roller 4d is disposed in a state of being brought into contact with the developing sleeve 2 with an appropriate pressure F. The elastic roller 4d is rotated in a counterclockwise direction indicated by an arrow.

That is, the toner layer carried as a magnetic attraction layer on the surface of the developing sleeve 2 by the magnetic field of the developer pumping magnetic pole S2 causes the elastic roller 4 to rotate as the developing sleeve 2 rotates.
The developer is conveyed to a contact portion between d and the developing sleeve 2 and passes through the contact portion, whereby the layer thickness is regulated and the developing sleeve 2 is coated as a predetermined thin layer.

As described above, the developer layer forming means 4a and 4b
4c and 4d include a type in which the members 4a and 4b are not in contact with the developer carrying / transporting unit 2, and a type in which the members 4c and 4d are in contact with the developer carrying / transporting means 2.

In particular, the latter contact-type developer layer forming means 4c and 4d are excellent in the ability to charge the developer.
It is suitable for a developing device adopting a method of replenishing a large amount of developer into the developing container 1 at a time.

Recently, in order to compensate for the disadvantages of the non-contact type and the contact type, a developing device provided with both the non-contact type and the contact type developer layer forming means has begun to be used.

[0031]

However, as the process speed, that is, the image forming speed becomes higher, the wear of the developer layer forming means and the developer carrying / transporting means and the deterioration of the developer itself become a problem. As a result, output image quality deteriorates due to image density reduction, fog, vertical white stripes, unevenness, and the like.

An object of the present invention is to prevent the deterioration of the output image quality, specifically, the image density, fog, vertical white stripes, unevenness, etc., and to improve the durability of the developing device.

Another object of the present invention is to suppress a sudden change in image quality of an output image due to the elastic developer layer forming means being separated from the developer carrying / transporting means at a certain point in time.

It is a further object of the present invention to reduce the burden on the user by prolonging the interval between the replenishments of the developer, to suppress the degradation of the output image quality after the replenishment of the developer, and to reduce the cost of the developer replenishment system.

Further, according to the present invention, the durability image density is reduced,
It is an object of the present invention to more effectively prevent adverse effects such as vertical white stripes and blotches.

[0036]

According to the present invention, there is provided a developing apparatus and an image forming apparatus having the following constitution.

(1) a developing container for storing a powder developer;
A developer carrying / transporting unit that carries and transports the developer in the developing container on the surface; and a developer layer forming unit that forms a developer layer on the surface of the developer carrying / transporting unit, A developing device for developing a latent image on the image carrying means with a developer layer carried / formed on the surface of the developer carrying / transporting means;
As a developer layer forming means for the developer carrying / transporting means, there is provided a rigid developer layer forming means and an elastic developer layer forming means, wherein the rigid developer layer forming means comprises the developer carrying / transporting means. The elastic layer developer layer forming means is separated from the developer carrying / transporting means for a period other than a predetermined period after the replenishment of the developer into the developing container without contacting the conveying means. Developing device.

(2) The means for forming an elastic developer layer comprises:
In a certain period after the replenishment of the developer into the developing container,
The developing device according to (1), wherein the pressing force on the developer carrying / transporting means decreases over time.

(3) The weight of the developer present in the developing container at the time of replenishing the developer into the developing container is 200 g or more, and the weight of the developer collectively supplied from outside to the developing container. The developing device according to (1) or (2), wherein the content is 5% or more and 30% or less.

(4) The surface of the developer carrying / transporting means is roughened by spraying alumina particles, and then roughened by spraying glass particles. The developing device according to any one of (3).

(5) The developing device according to any one of (1) to (4), wherein the powder developer has magnetism.

(6) The developing device according to any one of (1) to (5), wherein the developer carrying / transporting means is a rotating body.

(7) The developer carrying / transporting means is a rotating body, and is rotatably supported by the developer container. Developing device.

(8) An image forming apparatus for forming a latent image on the image carrying means and developing the latent image with a powder developer to form an image. The latent image on the image carrying means is developed. The developing device according to any one of (1) to (7), wherein the developing unit is (1).

<Operation> a) A non-contact type rigid developer layer forming means provided as a developer layer forming means for the developer carrying / transporting means, and an elastic type developer layer as a contact type Among the forming means, the contact type elastic developer layer forming means is separated from the developer carrying / transporting means during a period other than a certain period after the replenishment of the developer, so that the image density decreases and the non-image area is reduced. This prevents fog, vertical and white streaks, developer scattering, and local unevenness of the developer layer thickness appearing on a solid black image or a halftone image, thereby improving the durability of the developing device.

B) The contact-type elastic developer layer forming means reduces the pressure contact force on the developer carrying / transporting means with the lapse of time during a certain period after the supply of the developer into the developing container. As a result, it is possible to prevent a sharp change in the image quality of the output image during a certain period after the replenishment of the developer.

C) The weight of the developer present in the developing container at the time of replenishment of the developer is 200 g or more, and 5% to 30% of the weight of the developer collectively replenished from the outside into the developing container.
Because of the following, the image density decreases during a certain period after the replenishment of the developer, fog in the non-image area, vertical white streaks, developer scattering, and a local developer layer appearing on a solid black image or a halftone image Thickness unevenness can be more effectively prevented, and the burden on the user can be reduced by prolonging the developer supply interval.

D) The surface of the developer carrying / transporting means was roughened by spraying alumina particles, and then roughened by spraying glass particles. The adverse effects can be more effectively prevented.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS <Embodiment 1> (FIGS. 1 to 7) FIG. 1 is a schematic structural view of a developing device in the present embodiment.
FIG. 2 is a partially enlarged model view thereof. FIG. 13 to FIG.
Components and portions common to those in the developing device of FIG. 17 are denoted by the same reference numerals, and the description thereof will not be repeated.

The developing device A of this embodiment is provided with two types of developer layer forming means 4c and 4a of a contact type and a non-contact type with respect to the developing sleeve 2 as a developer carrying means.

The contact type developer layer forming means is an elastic developer layer forming means. Specifically, the elastic plate member 4c shown in FIG. 16 is used.

The non-contact type developer layer forming means is a rigid developer layer forming means, and specifically uses the blade member 4a shown in FIG. The blade member 4a is located downstream of the elastic plate member 4c in the rotation direction of the developing sleeve 2.

[0053] Developing Sleeve 2 In the developing device A of this example, the developing sleeve 2 as a developer carrying means is a hollow cylinder made of aluminum having a diameter of 24.5 mm, and has a SUS305 rotary support shaft at both ends thereof. Are rotatably supported on the front and rear side walls via bearings, and are driven to rotate at a peripheral speed of 470.4 mm / sec in a counterclockwise direction indicated by an arrow.

The outer surface of the developing sleeve 2 is firstly subjected to a surface roughening treatment by spraying spherical glass particles and then irregular alumina particles, and the outer surface has a center line average roughness of 0.25. It is a rough surface of ~ 0.40 µmRa.

The distance α between the developing sleeve 2 and the photosensitive member B is 2
10 to 250 μm.

The power source E applies a developing bias to the developing sleeve 2 with an amplitude of 1350 to 1650 V and a frequency of 2400.
A rectangular AC voltage of ０００3000 Hz is applied while being superimposed on a DC voltage variable between 0 V and +600 V.

[0057] Elastic Plate Member 4c FIG. 3 is a plan view of the elastic plate member 4c as a means for forming an elastic developer layer, in which an intermediate portion is omitted.

The elastic plate-like member 4c of this embodiment is made of urethane rubber and has a thickness of 0.9 to 1.2 mm and a width of 16 m.
m, length 298-307 mm, hardness 60-70 °.

One side of the long side of the elastic plate member 4c is clamped and held by the clamp member 9 with a width of about 5 mm.
The surface of the elastic plate-like member 4c is arranged to be pressed against the surface of the developing sleeve 2 with a pressure F by pressing against the surface thereof. The angle formed by the holding surface and the horizontal is about 45 °.

The long side of the elastic plate member 4c opposite to the side sandwiched by the clamp member 9 is a free end, and protrudes downstream in the rotation direction of the developing sleeve 2.

The width of the pressure contact area between the surface of the elastic plate member 4c and the developing sleeve 2 is 0 to 1 mm before endurance. An angle す formed by a vertical line b passing through the rotation center O of the development sleeve 2 and a line c connecting the rotation center O of the development sleeve 2 and the width center of the pressure contact area N is defined as the position of the pressure contact area N on the developing sleeve 2. The position is about 30 to 40 ° upstream of the vertical line b in the rotation direction of the developing sleeve 2.

The clamp member 9 holding the elastic plate-shaped member 4c is disposed so as to be slidable vertically along a guide member (not shown). As shown in FIG. A rack 11 is fixedly provided, and a pinion 12 is engaged with the rack 11. A stepping motor 13 rotates the pinion 12 forward and backward.

With this configuration, the stepping motor 13
, The clamp member 9 moves downward, and the pressing force F of the elastic plate member 4c against the developing sleeve 2 (the pressing force g / c per unit length along the axis of the developing sleeve 2).
m) increases. Conversely, when the stepping motor 13 is rotated in the reverse direction, the clamp member 9 moves upward, and the pressing force F of the elastic plate member 4c against the developing sleeve 2 decreases.

That is, under the control of the stepping motor 13,
The pressing force F of the elastic plate member 4c against the developing sleeve 2 can be controlled to be strong or weak.

[0065] FIG. 5 shows a blade member 4 as a rigid developer layer forming means.
It is a cross section enlarged model figure of a.

In this embodiment, the blade member 4a is S
Made of PCC, thickness 1.4 ~ 1.6mm, width 10 ~ 15m
m, length 300-320 mm, and its cross-sectional shape is trapezoidal.

The gap β between the blade member 4a and the developing sleeve 2 is set to 200 to 260 μm.

The position on the developing sleeve of the facing portion M of the blade member 4a with respect to the developing sleeve 2 is defined by a line d connecting the vertical line b passing through the rotation center O of the developing sleeve 2 and the facing portion M.
Is about 20 ° downstream of the vertical line b in the rotational direction of the developing sleeve 2.

[0069] Formation and Conveyance of Developer Layer (Toner Layer) The magnet roller 3 as the magnetic field generating means has six magnetic poles S1, N1, S3, N2, S2, and N3. The toner on the surface of the developing sleeve, which has been pumped by the developer pumping pole S1 (the vertical component magnetic flux density on the surface of the developing sleeve is from 600 Gauss to 700 Gauss) by the rotation of the developing sleeve 2, is formed into an elastic plate as an elastic developer layer forming means. The layer thickness is regulated and thinned by the member 4c and the blade member 4a as a rigid developer layer forming means.

In the developing section a, the toner layer raised at the developing pole N2 (the vertical component magnetic flux density at the surface of the developing sleeve is 950 Gauss to 1050 Gauss) develops the electrostatic latent image on the surface of the photosensitive member B. The toner not subjected to the development is returned into the developing container 1 by the subsequent rotation of the developing sleeve 2.

In the developing device of this embodiment, the average charge q of the magnetic developer (toner) on the developing sleeve 2 at normal temperature and normal humidity by the suction method is -9 to -12 μC / g, and the coating amount m
Is 0.8 to 1.0 mg / cm ² , and the initial weight average particle size of the developer is 6.2 to 6.8 μm.

[0072] As shown in FIG. 1, the developing device A of this embodiment has a toner container storage chamber 14 in the developing container 1, and the toner cartridge 15 is inserted into the storage chamber and opened to open the toner cartridge. From 15, toner is supplied to the developing container 1. FIG. 6 is an external perspective view of the toner cartridge 15. The toner cartridge 15 has a cylindrical container filled with replenishing toner. Reference numeral 15a denotes a slit-shaped opening provided in the generatrix direction of the cylindrical container, and is always sealed with a band tape.

The amount of the developer in the developing container 1 is
Is detected by a known developer amount detecting means 7 (FIG. 1) provided in the vicinity of, and the detected developer amount information is input to a main control means (main control circuit) 17. When the amount of the developer in the developing container 1 decreases to 100 to 140 g, the main control means 17 issues a developer replenishment signal to notify the user. Reference numeral 18 denotes a display unit provided on an operation panel unit or the like of the image forming apparatus, and performs the above notification.

The user pulls out the empty toner cartridge 15 inserted into the toner cartridge storage chamber 14 of the developing container 1, inserts a new toner cartridge into the storage chamber 14, opens the toner cartridge, and opens the opening 15a. The rotation operation of the toner cartridge 15 is performed so that the toner cartridge 15 is turned sideways toward the inside of the container 1.

The toner in the toner cartridge 15 is rotated by the developer conveying means 16 built in the cartridge (about 100 revolutions per minute) so that the opening 15a (width w
It is extruded from the toner cartridge 15 into the developing container 1 through an angle θ = 0 to 5 ° (upward is positive) between a line connecting the center of the width and the center of the cylinder to the horizontal line, about 8 mm. The amount of toner replenishment from the toner cartridge 15 to the developing container 1 is 590 g.
It is possible to output a sheet of standard density image.

The toner supplied from the toner cartridge 15 to the developing container 1 is supplied to the first and second toner stirring and conveying members 5.
While being stirred in the longitudinal direction by the rotation of 6, the toner is conveyed in the direction of the developing sleeve 2 and supplied to the rear side of the developing sleeve 2.

[0077] Control of Pressing Force F of Elastic Plate Member 4c The main control means 17 controls the stepping motor 13 to control the elastic plate member 4c with respect to the developing sleeve 2 in accordance with the image output frequency (number of sheets) X after the developer is supplied. Is controlled so that the pressure contact force F (g / cm) of FIG.

In this embodiment, the elastic plate member 4c is separated from the developing sleeve 2 before the developer is supplied and after 101 sheets after the developer is supplied.

In this embodiment, there is almost no change in image quality when the elastic plate-shaped member 4c as the means for forming the elastic developer layer is separated from the developing sleeve 2, and the image density decrease after the replenishment of the developer is the worst. The value is 0.05.

The stable image density after output of about 300,000 sheets (converted to Japanese Industrial Standards A row No. 4 size) is 1.33, and the number of white streaks after supply of the developer is several.

<Examples 2 to 6> (Table 1) Table 1 shows some examples of the developing apparatus in which the settings were variously changed in Example 1 as Examples 2 to 6 and Comparative Example 1.

[0082]

[Table 1] <Embodiment 7> (FIGS. 8 to 12) FIG. 8 is a schematic configuration diagram of a developing device in this embodiment.
FIG. 9 is a partially enlarged model view thereof. FIG. 13 to FIG.
Constituent members and portions common to the developing device of FIG. 17 and the developing device of the first embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

In the developing device A of the present embodiment, the elastic roller 4d shown in FIG. 17 is used as the developer layer forming means of the contact type with the developing sleeve 2 as the developer carrying means, and the non-contact type rigid body is used. The above-described rigid roller 4b shown in FIG. 15 was used as the developer layer forming means. The rigid roller 4b is located downstream of the elastic roller 4d in the rotation direction of the developing sleeve 2.

[0084] Developing Sleeve 2 In the developing device A of this example, the developing sleeve 2 as a developer carrying means is a hollow cylinder made of aluminum having a diameter of 20 mm, and is rotationally driven at a peripheral speed of 157.5 mm / sec in a counterclockwise direction indicated by an arrow. You.

The outer surface of the developing sleeve 2 is subjected to a blast treatment by spraying spherical glass particles, and then coated with a phenol resin, crystalline graphite, and carbon and having a volume resistance of 100 Ωcm or less (film thickness of 10 μm).
１４14 μm), and the center line average roughness of the outer surface is
It is a rough surface of 0.70 to 0.90 μm Ra.

The distance α between the developing sleeve 2 and the photosensitive member B is 2
70 to 330 μm.

The power supply E applies a developing bias to the developing sleeve 2 with an amplitude of 1250 to 1350 V and a frequency of 1750.
矩形 1850 Hz rectangular AC voltage is -400 to -600
The voltage is superimposed on a DC voltage that is variable between V and V.

[0088] Elastic Roller 4d The elastic roller 4d as a means for forming an elastic developer layer includes:
A diameter d of about 15～16Mm, the surface layer 4 ₁ is composed of silicone rubber (thickness 5 to 6 mm), the lower layer and the rotation shaft 4 ₂ is formed of SUS316. Rotary axis 4 ₂
Is rotatably supported on the side wall of the developing device via a bearing.

The position of the pressure contact area N between the elastic roller 4d and the developing sleeve 2 on the developing sleeve 2 is a vertical line b passing through the rotation center O of the developing sleeve 2 and the pressure contact area N between the rotation center O of the developing sleeve 2 and the pressure contact area N. The angle ζ formed by the line c connecting the width center of the developing sleeve 2 is about 40 ° upstream of the vertical line b in the rotation direction of the developing sleeve 2.

The elastic roller 4d is disposed so as to freely slide up and down along a guide member (not shown).
As shown at 0, a rack 11 is integrally provided in the bearing member 19 of the elastic roller 4d in the vertical direction, and a pinion 12 is engaged with the rack 11. The pinion 12 is rotated forward and backward by a stepping motor 13.

With this configuration, the stepping motor 13
, The rack 11 moves downward, and the pressing force F of the elastic roller 4 d against the developing sleeve 2 increases.
Conversely, the stepping motor 13 is rotated in the reverse direction to
1 moves upward, and the pressing force F of the elastic roller 4d against the developing sleeve 2 decreases.

That is, by controlling the stepping motor 13,
The pressing force F of the elastic roller 4d against the developing sleeve 2 can be controlled to be strong or weak.

The elastic roller 4d operates during the developing process (A4
When the transfer material of the size is fed sideways, it is stationary at T ₁ = 2 seconds, but at other times (in the case of continuous output operation, after one output operation command is completed, a single output operation is performed). In the case of ( ₂ ), immediately after the development step) T ₂ = 1.5 seconds at an angular velocity of ω ₂ = 0.01 revolutions / second and γ = 5.4 ° in the counterclockwise direction of the arrow by a driving means (not shown) I do. The rotation / stop of the elastic roller 4d is controlled by a microcomputer, but will not be described in detail here.

The times T ₁ and T ₂ and the angle γ are of course appropriately changed depending on the size of the output image.

A scraping member 20 may be provided for the purpose of removing the developer adhered to the outer periphery of the elastic roller 4d. As the material, an elastic sponge, rubber or the like can be suitably used.

[0096] Rigid Roller 4b The rigid roller 4b as a rigid developer layer forming means is a hollow cylinder made of aluminum having a diameter of 16 mm, and is rotationally driven in a counterclockwise direction indicated by an arrow at a peripheral speed of 84 mm / sec. Inside it, a magnet roller 21 as a magnetic field generating means magnetized to have two magnetic poles is inserted and fixedly arranged. Further, a member 22 for removing the developer adhered to the rigid roller 4b and conveyed in the counterclockwise direction is brought into contact with the rigid roller 4b. Urethane rubber or the like can be suitably used as the material.

The clearance β between the rigid roller 4b and the developing sleeve 2 is set to 200 to 300 μm.

The position of the opposed portion M of the rigid roller 4b on the developing sleeve 2 on the developing sleeve is
An angle ψ between a vertical line b passing through the rotation center O of the developing sleeve 2 and a line d connecting the opposing portion M is about 15 ° downstream of the vertical line b in the rotation direction of the developing sleeve 2.

[0099] Formation and Conveyance of Developer Layer (Toner Layer) The magnet roller 3 as the magnetic field generating means has six magnetic poles S1, N1, S3, N2, and S2. The rotation of the developing sleeve 2 causes the developer to be pumped up to the pole S2 (the vertical component magnetic flux density at the surface of the developing sleeve is from 650 Gauss to 770).
The toner on the surface of the developing sleeve pumped up by the Gauss) is applied to an elastic roller 4d as a means for forming an elastic developer layer.
Then, the layer thickness is regulated by the rigid roller 4b as a rigid developer layer forming means, and the layer is thinned.

In the developing section a, the toner layer raised at the developing pole S1 (the vertical component magnetic flux density at the surface of the developing sleeve is from 900 Gauss to 1000 Gauss) develops the electrostatic latent image on the surface of the photosensitive member B. The toner not subjected to the development is returned into the developing container 1 by the subsequent rotation of the developing sleeve 2.

In the developing device of this embodiment, the average charge q of the developer (toner) on the developing sleeve 2 at normal temperature and normal humidity by the suction method is +12 to +15 μC / g, and the coating amount m is 0.7 to 0. 1.9 mg / cm ² , and the initial weight average particle size of the developer is 7.4 to 7.8 μm.

. Developing agent supply The developing device A of this embodiment also has a toner cartridge storage chamber 14 in the developing container 1, and inserts and opens the toner cartridge 15 in this storage chamber to remove the toner cartridge 15 from the developing container. 1 is supplied with toner.

The developer amount in the developing container 1 is detected by the developer amount detecting means 7 provided near the developing sleeve 2, and the detected developer amount information is inputted to the main control means 17. The main controller 17 controls the developer amount in the developer container 1 to 30 to
When the weight is reduced to 60 g, a developer supply signal is issued to notify the user.

The user pulls out the empty toner cartridge 15 inserted into the toner cartridge storage chamber 14 of the developing container 1, inserts a new toner cartridge into the storage chamber 14, opens the toner cartridge, and opens the opening 15a. The rotation operation of the toner cartridge 15 is performed so that the toner cartridge 15 is turned sideways toward the inside of the container 1.

The toner in the toner cartridge 15 is rotated by the developer conveying means 16 (about 70 revolutions per minute) incorporated in the toner cartridge 15 so that the opening 15a (width w: about 7 mm, width center, center of cylinder) The connecting line is extruded from the toner cartridge 15 into the developing container 1 through an angle θ = 0 to 5 ° (the upper part is defined as positive) formed by the horizontal line.

The toner replenishment amount from the toner cartridge 15 to the developing container 1 is 380 g, and it is possible to output about 7600 sheets of standard density images by one replenishment of the developer.

The toner supplied from the toner cartridge 15 to the developing container 1 is conveyed in the direction of the developing sleeve 2 while being stirred in the longitudinal direction by the rotation of the toner stirring and conveying member 6, and is supplied to the rear side of the developing sleeve 2. You.

. Control of Pressing Force F of Elastic Roller 4d The main control means 17 controls the stepping motor 13 to control the pressing force F of the elastic roller 4d against the developing sleeve 2 in accordance with the number of image outputs (number of sheets) X after the replenishment of the developer. Is controlled to change as shown in FIG.

In this embodiment, the elastic roller 4d is separated from the developing sleeve 2 before the developer replenishment and after 1001 sheets after the developer replenishment.

Also in this embodiment, there is almost no change in the image quality when the elastic roller 4d as the means for forming the elastic developer layer is separated from the developing sleeve 2, and the image density decrease after the replenishment of the developer is the worst value. 0.07.

The stable image density after output of about 250,000 sheets (converted to Japanese Industrial Standard A row No. 4 size) is 1.29, and the number of white streaks after developer replenishment is several.

Here, the first embodiment and the seventh embodiment are described.
FIG. 12 shows the relationship between the developer amount W _tres in the developing container 1, the developer supply amount W _trep, and the performance of the developing device.

In the region above the straight line W _tres res = 0.3 ^* W _trep and to the left of W _trep = 200 g, the rate at which the user perceives that “the developer supply interval is short” is high.
_In the area below _tres = 0.05 ^* W _trep, the image quality after developer replenishment (evaluated by (good) / (good) × (impossible)) is poor.
(Possible).

<Embodiments 8 to 12> (Table 2) Table 2 shows some examples of the developing apparatus in which the settings were variously changed in Embodiment 7 as Examples 8 to 12 and Comparative Example 2.

[0115]

[Table 2] <Others> a) The above 12 embodiments have been described, but it is needless to say that changes can be made within the scope of the present invention.

B) a developing device having a plurality of developer carrying / transporting means, a developing device in which the developer carrying / transporting means is in contact with the image carrying means, a developing device using a one-component developer containing no magnetic material, The present invention is also applicable to a developing device using a two-component developer composed of a toner and a carrier, a developing device having a belt-like developer carrying / conveying unit, or a belt-like developer layer forming unit.

C) In the image forming apparatus, the image bearing means is not limited to the electrophotographic photosensitive member. An electrostatic recording dielectric or a magnetic recording magnetic material may be used. Further, an electrostatic latent image forming means for these image bearing means is also appropriate. Even in the transfer method,
The direct method may be used.

[0118]

As is apparent from the above description, according to the present invention, the elastic developer layer forming means is separated from the developer carrying / transporting means for a period other than a certain period after the replenishment of the developer. As a result, reduction of image density, fogging of non-image areas, vertical white streaks, developer scattering, and local unevenness of developer layer thickness appearing on solid black images and halftone images are prevented, and the durability of the developing device is prevented. The effect that improvement can be achieved is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a developing device according to a first embodiment.

FIG. 2 is a partially enlarged model diagram thereof.

FIG. 3 is a plan view of an elastic plate-shaped member as a means for forming a developer layer of an elastic body, in which an intermediate portion is omitted.

FIG. 4 is a schematic view of a configuration of a pressing force control unit for the elastic plate-shaped member.

FIG. 5 is a schematic cross-sectional view of a blade member as a means for forming a rigid developer layer.

FIG. 6 is an external perspective view of the toner cartridge.

FIG. 7 is a press-contact force control table for an elastic plate member.

FIG. 8 is a schematic configuration diagram of a developing device according to a second embodiment.

FIG. 9 is a partially enlarged model view thereof.

FIG. 10 is a schematic diagram of a configuration of a pressing force control unit for an elastic roller.

FIG. 11 is a pressing force control table for an elastic roller.

FIG. 12 shows a relationship between a developer amount in a developing container, a developer replenishing amount, and performance of a developing device.

FIG. 13 is a schematic configuration diagram of a conventional developing device.

FIG. 14 is a partially enlarged model view thereof.

FIG. 15 is a partial model view of a developing device in which a developer layer forming unit is a non-contact rigid roller.

FIG. 16 is a partial model view of a developing device in which a developer layer forming unit is a contact elastic plate member.

FIG. 17 is a partial model view of a developing device in which a developer layer forming unit is a contact elastic roller.

[Explanation of symbols]

Reference Signs List A developing device B electrophotographic photosensitive member (image carrying means) 1 developing container 2 developing sleeve (developer carrying / transporting means) 4a, 4b, 4c, 4d non-contact or contact type developer layer forming means 5.6 developer Stirring / conveying member 11-13, 17 Pressure contact force control means

Claims (8)

[Claims] 1. A developer container for storing a powder developer, a developer carrying / transporting means for carrying and transporting the developer in the developing container on a surface, and a developer carrying / transporting means on the surface of the developer carrying / transporting means. A developing device having a developer layer forming means for forming a layer of developer, wherein the developing device develops a latent image on the image carrying means with the developer layer carried and formed on the surface of the developer carrying / transporting means; As a developer layer forming means for the developer carrying / transporting means, there is provided a rigid developer layer forming means and an elastic developer layer forming means, wherein the rigid developer layer forming means comprises the developer carrying / transporting means. The elastic developer layer forming means is separated from the developer carrying / transporting means for a period other than a predetermined period after the developer is supplied into the developing container without contacting the developing means. Developing device. 2. The method according to claim 1, wherein the pressing force applied to the developer carrying / transporting means decreases over time during a certain period after the developer is supplied to the developing container. The developing device according to claim 1, wherein the developing device is operated. 3. The weight of the developer present in the developing container at the time of replenishing the developer into the developing container is 200 g or more, and The developing device according to claim 1, wherein the content is 5% or more and 30% or less. 4. The method according to claim 1, wherein the surface of said developer carrying / transporting means is roughened by spraying alumina particles, and then roughened by spraying glass particles. The developing device according to any one of the above. 5. The developing device according to claim 1, wherein the powder developer has magnetism. 6. The developing device according to claim 1, wherein said developer carrying / transporting means is a rotating body. 7. The developing device according to claim 1, wherein said developer carrying / transporting means is a rotating body, and is rotatably supported by said developer container. . 8. An image forming apparatus which forms a latent image on an image bearing means, develops the latent image with a powder developer, and executes image formation, and develops the latent image on the image bearing means. The developing device according to claim 1, wherein the means is provided.