JP2000075630A - Developing device, process cartridge and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of a ghost image and to make the image density non-uniform in the longitudinal direction of a developer carrier by reliably performing toner stripping by a developer supply and stripping means. The present invention provides an image forming apparatus capable of stably obtaining a good image having a uniform image density and a developer carrying member for carrying a one-component developer.
A developing device 4 for visualizing the electrostatic latent image on the image carrier 1 at a developing position opposite to the image carrier 1 having an electrostatic latent image on the surface; A straight line F connecting the rotation center and the rotation center of the developer carrier 42
And an angle (α) between the rotation center of the image carrier 1 and the straight line E connecting the rotation center of the developer carrier 42 with respect to the straight line F, is at least 80 degrees upstream of the rotation direction of the developer carrier 42 and 100 degrees.
Degrees or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for visualizing an electrostatic latent image formed on an image carrier using, for example, an electrophotographic method or an electrostatic recording method as a toner image using a developing device. The present invention relates to a developing device, a process cartridge, and an image forming apparatus used for, for example, a copying machine, a printer, and the like, which obtain a permanent image by transferring and fixing an image on a recording material.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus using, for example, an electrophotographic system has a drum-shaped electrophotographic photosensitive member, that is, a photosensitive drum, rotatably provided as an image carrier at a substantially central portion thereof. Is uniformly charged by the charging means. Thereafter, the surface of the photoreceptor is exposed, and an electrostatic latent image corresponding to an image signal is formed on the surface. The electrostatic latent image reaches a position facing the developing device with the rotation of the photoconductor, is visualized by the developer, and a so-called toner image is formed on the photoconductor. Thereafter, the toner image is electrostatically transferred onto a recording material by a transfer unit, and further fixed by heat and pressure by a fixing device to form a permanent image on the recording material. Further, a cleaning device for removing toner and the like remaining on the photoconductor after the transfer is completed is provided at a desired position.

[0003] In an image forming apparatus having the above-described schematic configuration, a developing apparatus using a one-component developer as a developer is known. In particular, a developing device using only non-magnetic toner particles (hereinafter simply referred to as “toner”) as a non-magnetic one-component developer is known.

In such a developing device, a rotatable sleeve is used to transport the toner to a developing position facing the photosensitive drum and to attach the toner to the electrostatic latent image on the photosensitive drum to form a toner image. , That is, those having a developing sleeve are known.

In recent years, there has been a further demand for improvements in the resolving power and sharpness of an image formed by an image forming apparatus. In such a developing apparatus, it is important to form a thin layer of toner on a developing sleeve. Thus, various proposals have been made regarding a method for forming a thin layer of toner and a developing device for realizing the method.

For example, in a developing device disclosed in Japanese Patent Application Laid-Open No. Sho 54-43038, an elastic blade as a means for regulating the thickness of a developer layer made of rubber or metal is brought into contact with the surface of the developing sleeve. That is, a thin layer of toner is formed on the developing sleeve by regulating the layer thickness by passing the toner between the abutting portions of the elastic blade and the developing sleeve, and developing at the abutting portions. Is applied to the toner.

In the prior art described above, in order to control the non-magnetic toner particles by the elastic blade, a means for supplying the toner onto the developing sleeve is separately required. That is, as is conventionally known, in the case of a developing device using magnetic toner particles as a one-component developer, toner can be supplied onto the developing sleeve by a magnetic force generated by a magnet provided in the developing sleeve. On the other hand, in the case of a developing device using non-magnetic toner particles, this is impossible.

Therefore, in order to supply the toner to the developing sleeve, conventionally, an elastic roller-shaped member using a foamed rubber material such as polyurethane foam or sponge, or a brush material has been brought into contact with the developing sleeve. Various proposals have been made.

FIG. 5 shows an example of a developing device using a conventional one-component developer.

The developing device 4 contains toner in a developing container 41, and a part of the developing container 41 on the side where the developing device 4 and the photosensitive drum 1 face each other is open. A developing sleeve 42 as a developer carrying member is supported by the developing container 41 so as to be rotatable in the direction of arrow B so as to expose a part in the circumferential direction. As can be understood from FIG. 3, spacers 47 are provided at both ends in the longitudinal direction of the developing sleeve 42 as gap regulating members.
When the spacer 47 comes into contact with the surface of the photosensitive drum 1, the surface of the photosensitive drum 1 and the surface of the developing sleeve 42 face each other at a predetermined distance.

An elastic blade 44 as a developer layer thickness regulating means for regulating the amount of toner carried on the surface of the developing sleeve 42 is in contact with the developing sleeve 42. An elastic roller 43 as a developer supply and stripping means is in contact with the developing sleeve 42 at a position on the upstream side in the rotation direction of 42.

When the developing device 4 starts the developing operation, the toner is stirred by the rotation of the stirring member 45 in the direction of arrow D,
Further, the sheet is conveyed to the elastic roller 43 side. The toner is carried on the surface of the developing sleeve 42 while being preliminarily charged by the rubbing with the elastic roller 43, and then, while the layer thickness is regulated by the elastic blade 44, a desired charge is given by the rubbing at this time. .

Thereafter, the toner carried and transported to the developing position facing the photosensitive drum 1 with the rotation of the developing sleeve 42 flies onto the photosensitive drum 1 by the developing bias voltage applied to the developing sleeve 42, and It selectively adheres to the electrostatic latent image on one surface to form a toner image.

The toner remaining on the surface of the developing sleeve 42 without contributing to the development is conveyed again into the developing container 41 by the rotation of the developing sleeve 42, and the elastic roller 43 peels off the toner, whereby the toner in the developing container 41 is removed. Mixed with.

In the developing device 4 described above, the elastic roller 4
As the third function, it is necessary to provide a sufficient toner supply capability and a toner stripping capability. In particular, it is necessary to pay attention to the toner stripping capability that has not contributed to development.

That is, when the toner stripping ability becomes insufficient, the toner newly supplied onto the developing sleeve 42 and the toner remaining on the developing sleeve 42 without contributing to the development are developed. They will be mixed on the surface. Therefore, when the toner is conveyed to the portion facing the photosensitive drum 1 after passing through the elastic blade 44, a difference in developing property occurs between these toners, and as a result, a so-called ghost image is generated, which is preferable in image quality. Absent.

Accordingly, the elastic roller 43 is required to satisfy both the toner supply function and the toner stripping function.
The developing sleeve 42 is brought into contact with the developing sleeve 42 with a predetermined penetration amount and a contact width (hereinafter, referred to as “nip width”).

By employing the configuration of the conventional developing device as described above, a thin layer of toner can be favorably formed on the developing sleeve 42, and the electrostatic latent image on the photosensitive drum can be favorably developed. Became possible.

[0019]

However, in recent years,
In order to achieve higher image quality, the particle size of the toner used as a developer tends to be smaller, and a new problem has arisen. That is, a small particle size toner (the average particle size is
10 μm) is a toner having a normal particle size (the average particle size is 10 μm).
m to 15 μm), it tends to be less likely to be peeled off from the developing sleeve 42. In order to prevent the occurrence of the ghost image described above, it is necessary to further improve the peeling ability of the elastic roller 43.

In order to address the above problem, a foamed elastic roller having sufficient performance for supplying toner is
The developing sleeve 42 of the elastic roller 43
For example, a method of increasing the amount of intrusion into the nip, increasing the nip width, and increasing the number of rotations can be considered.

However, by taking such measures, it is possible to prevent the occurrence of a ghost image, but on the other hand, the image density of the image to be formed is in a direction orthogonal to the recording material conveyance direction, that is, A phenomenon occurs in which the density becomes non-uniform in the longitudinal direction of the developing sleeve 42, and the density is high at the center in this direction and low at both ends.

According to the study by the present inventors, it has been found that the above-mentioned non-uniformity of image density (image density unevenness) is caused by the following.

In the conventional developing device 4 shown in FIG. 5, as a result of a detailed study of the gap between the developing sleeve 42 and the photosensitive drum 1, the longitudinal center of the gap between the developing sleeve 42 and the photosensitive drum 1 It turned out that it became narrow compared with the longitudinal direction both ends. Therefore, during the development operation,
When a developing bias voltage in which a DC bias voltage is superimposed on an AC bias voltage is applied to the developing sleeve 42, the electric field intensity at the time of development is reduced due to the above-described gap difference.
It becomes stronger at the center in the longitudinal direction and weaker at both ends. As a result, a difference occurs between the developability at the center in the longitudinal direction of the developing sleeve 42 and the developability at both ends, and a phenomenon occurs in which the image density at the center increases.

The cause of the narrowing of the gap at the longitudinal center of the developing sleeve 42 is the bending of the developing sleeve 42. That is, as understood from FIG. 3, both ends in the longitudinal direction of the developing sleeve 42 are supported by bearing portions of the developing container 41, while
This is because the elastic roller 43 and the elastic blade 44 are in contact with each other, so that their pressure causes bending.

As described above, the spacers 47 (FIG. 3) are provided at both ends in the longitudinal direction of the developing sleeve 42. When the spacers 47 contact the photosensitive drum 1, the developing sleeve 42 and the photosensitive drum 1 are separated. A predetermined gap is maintained. However, both ends in the longitudinal direction of the developing sleeve 42 are kept at a predetermined gap with respect to the photosensitive drum 1 by the spacer 47, while the central portion in the longitudinal direction is bent in the direction of the photosensitive drum 1 by the above-mentioned two pressures. It has been found that the gap with No. 1 becomes narrow.

According to the study of the present inventors, the cause of the bending of the developing sleeve 42 is that of the elastic roller 43 and the elastic blade 44 which are in contact with the developing sleeve 42,
Elastic roller 42 with high linear pressure on developing sleeve 42
Turned out to be particularly dominant. On the other hand, the contribution of the elastic blade 44 to the bending was small. Generally, the elastic roller 43 comes into contact with the developing sleeve 42 at a linear pressure of about 30 g / cm to 100 g / cm, whereas the linear pressure of the elastic blade 44 is as low as 10 g / cm to 20 g / cm. The effect is small.

However, the toner used and the developing sleeve 4
In the case where it is necessary to increase the contact pressure of the elastic blade 44 with the developing sleeve 42 due to the surface properties of No. 2, the influence on the bending of the elastic blade 44 increases.

As a countermeasure against the above-described problem of uneven image density in the longitudinal direction of the developing sleeve 42 due to the bending of the developing sleeve 42, the following countermeasures can be considered.

That is, a method of reducing the contact pressure of the developing roller 43 against the developing sleeve 42, which is a main factor for bending the developing sleeve 42, or increasing the strength (rigidity) of the developing sleeve 42 on the side to be bent. It is.

Here, in order to increase the strength of the developing sleeve 42, it is necessary to take measures such as enlarging the outer diameter of the sleeve, increasing the wall thickness in the case of a pipe shape, increasing the thickness of the sleeve, or making it solid. It is conceivable to adopt a countermeasure method in terms of the material, such as using a material having high rigidity, such as various SUSs.

However, with these methods, it is difficult to completely eliminate the bending. Further, the method of reducing the contact pressure of the elastic roller 43 makes it difficult to scrape off the toner, which is not preferable. The method of increasing the strength of the developing sleeve 42 reduces the size of the developing device and the image forming device.
From the viewpoints of weight reduction and cost reduction, all undesirable results are produced.

Accordingly, it is an object of the present invention to prevent the occurrence of a ghost image by reliably performing toner stripping by the developer supply and stripping means, and to make the image density non-uniform in the longitudinal direction of the developer carrying member. It is an object of the present invention to provide an image forming apparatus capable of preventing the occurrence of the image formation and stably obtaining a good image having a uniform image density.

[0033]

The above object is achieved by a developing device, a process cartridge and an image forming apparatus according to the present invention. In summary, a first aspect of the present invention provides a developing container for storing a one-component developer as a developer, a rotatable developer carrier extending to an opening of the developing container, A rotatable developer supply and peeling roller for supplying and peeling the developer onto the developer carrier in contact with the body surface, and a direction of rotation of the developer carrier of the developer supply and peeling roller; A developer layer thickness regulating means for abutting the developer carrier on the downstream side to regulate the layer thickness of the one-component developer on the developer carrier, and carrying the one-component developer. The developer carrying member is a developing device that visualizes an electrostatic latent image on the image carrying member at a developing position facing an image carrying member carrying an electrostatic latent image on a surface,
A first straight line connecting the rotation center of the developer supply and stripping roller and the rotation center of the developer carrier, and a second straight line connecting the rotation center of the image carrier and the rotation center of the developer carrier. The angle (α) between the line and the straight line is 80 degrees or more on the upstream side in the rotation direction of the developer carrier when viewed from the first line.
A developing device characterized in that the angle is not more than 00 degrees.

According to the second aspect of the present invention, in the process cartridge detachable from the image forming apparatus main body, the image carrier, at least the developer carrier, the developer supply and peeling roller, and the developer layer thickness regulating means are provided. A process unit acting on the image carrier including a developing device provided with: a first straight line connecting the rotation center of the developer supply and peeling roller and the rotation center of the developer carrier; An angle (α) between a rotation center of the image carrier and a second straight line connecting the rotation center of the developer carrier is 80 to the upstream side in the developer carrier rotation direction with respect to the first straight line. Over 10
There is provided a process cartridge characterized by being set to 0 degrees or less.

According to the third aspect of the present invention, there is provided an image forming apparatus in which a process cartridge is detachable and which forms an image on a recording material, wherein (a) an image carrier, at least a developer carrier, a developer supply and A process unit acting on the image carrier including a peeling roller and a developing device having a developer layer thickness regulating unit; and a rotation center of the developer supply and peeling roller and the developer carrier. An angle (α) formed by a first straight line connecting the rotation center of the image carrier and a second straight line connecting the rotation center of the image carrier and the rotation center of the developer carrier is viewed from the first straight line. Mounting means for removably mounting a process cartridge having an angle of 80 degrees or more and 100 degrees or less on the upstream side in the rotation direction of the developer carrier, and (b) conveying means for conveying the recording material; Have Image forming apparatus is provided, wherein.

In the first to third aspects of the present invention, according to one embodiment, the angle (α) is approximately 90 degrees.
Further, according to another embodiment, the developer layer thickness regulating means is provided at a point symmetric position with respect to a position at which the developer supply and peeling roller abuts on the developer carrier. Contact the body.

According to a fourth aspect of the present invention, there is provided a developing container for containing a one-component developer as a developer, a rotatable developer carrier extending to an opening of the developing container, A rotatable developer supply / peeling-off roller that abuts on the surface of the developer carrier and supplies and peels the developer onto the developer carrier, and the developer carrier of the developer supply / peeling-off roller A developer regulating means for abutting the developer carrier on the downstream side in the rotation direction to regulate the layer thickness of the one-component developer on the developer carrier, and carrying the one-component developer. A developing device for visualizing an electrostatic latent image on the image carrier at a developing position opposed to the image carrier having an electrostatic latent image on a surface thereof; Pressing force of the roller against the developer carrier, and The angle (β) between the resultant vector of the thickness regulating means and the pressure applied to the developer carrier and the straight line connecting the rotation center of the image carrier and the rotation center of the developer carrier is 80 degrees or more. , 100 degrees or less.

According to the fifth aspect of the present invention, in an image forming apparatus detachable process cartridge, an image carrier, at least a developer carrier, a developer supply / peeling roller, and a developer layer thickness regulating means are provided. Process means acting on the image carrier including a developing device provided with the developer supply and the pressing force of the peeling roller against the developer carrier, and the developer layer thickness regulating means of the The angle (β) formed by the resultant vector of the pressure applied to the developer carrier and the straight line connecting the rotation center of the image carrier and the rotation center of the developer carrier is 80 degrees or more and 100 degrees or less. A process cartridge is provided.

According to the sixth aspect of the present invention, there is provided an image forming apparatus for detachably attaching a process cartridge and forming an image on a recording material, comprising: (a) an image carrier, at least a developer carrier, a developer supply and Processing means for operating on the image carrier, including a peeling roller and a developing device having a developer layer thickness regulating means, wherein the developer supply and peeling roller are applied to the developer carrier. The angle formed by the resultant vector of the pressure, the force applied to the developer carrier by the developer layer thickness regulating means, and the straight line connecting the rotation center of the image carrier and the rotation center of the developer carrier. (Β) is 80
Mounting means for removably mounting a process cartridge having a degree of not less than 100 degrees and less than 100 degrees,
(B) An image forming apparatus, comprising: a conveying unit that conveys the recording material.

In the fourth to sixth aspects of the present invention, according to one embodiment, the resultant force vector of the developer layer thickness regulating means with the pressing force applied to the developer carrier, and the rotation center of the image carrier. An angle (β) formed by a straight line connecting the rotation center of the developer carrier and the rotation center is approximately 90 degrees.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a developing device, a process cartridge and an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Embodiment 1 FIG. 1 shows a schematic configuration of an embodiment of an image forming apparatus according to the present invention. It should be understood that, according to this embodiment, the invention is embodied in a laser beam printer, but the invention is not so limited.

According to the present embodiment, the image forming apparatus supports a drum-shaped electrophotographic photosensitive member as an image carrier, that is, a photosensitive drum 1 so as to be rotatable in the direction of arrow A. The surface of the photosensitive drum 1 is uniformly charged by a charging roller 2 as charging means. Then, the optical system 3 corresponding to the image information
Performs exposure on the surface of the photosensitive drum 1, and an electrostatic latent image corresponding to an image signal is formed on the surface of the photosensitive drum 1.

The electrostatic latent image reaches a position facing the developing device 4 as the photosensitive drum 1 rotates, and is visualized by the developer, so that a so-called toner image is formed on the photosensitive member. Next, the toner image is conveyed to a position where the transfer roller 7 as a transfer unit and the photosensitive drum 1 come into contact with each other.

On the other hand, the recording material P stored in the cassette 5
Is fed into the image forming apparatus by the feed roller 6 in synchronization with the toner image on the photosensitive drum 1 entering the transfer position, and is conveyed to the transfer position by the conveying means 14.

The toner image on the photosensitive drum 1 reaching the transfer position is electrostatically transferred by the transfer roller 7 onto the recording material P that has reached the transfer position. Thereafter, the recording material P carrying the unfixed toner image is further conveyed to the fixing device 9, and the unfixed toner is fixed on the recording material P by heat and pressure.

Thereafter, the P on the recording material on which the permanent image is formed
Is discharged outside the image forming apparatus. Further, the toner remaining on the photosensitive drum 1 after the transfer is scraped off by the cleaning blade 10 and stored in the waste toner storage container 11 of the cleaning device 8 to be repeatedly subjected to the image forming operation.

According to the present embodiment, the developing device 4 is formed as a unit and is detachable from the image forming apparatus main body.
Further, the image forming apparatus of the present embodiment performs so-called reversal development in which a portion of the surface of the photosensitive drum 1 uniformly charged by the charging roller 2 where the charge is attenuated by exposure is visualized by toner.

Next, the developing device 4 of this embodiment will be described in more detail. FIG. 2 shows a schematic configuration of an example of the developing device according to the present invention.

The developing device 4 contains only a non-magnetic one-component developer, that is, non-magnetic toner particles (toner) as a developer in a developing container 41. The developing container 41 extends in the longitudinal direction of the developing container 41, and has an opening at a position facing the photosensitive drum 1. In this opening, the developing container 41 is driven to rotate in the direction of arrow B as a developer carrier. Developing sleeve 42
However, it is provided so that the half circumferential surface is exposed outside the developing container 41, and the opposite half circumferential surface protrudes into the developing container 41.

The surface of the developing sleeve 42, which is exposed outside the developing container 41, and the surface of the photosensitive drum 1 are designed to be kept at a small interval by a spacer 47 (FIG. 3) as a gap regulating means.

The surface of the developing sleeve 42 has desired irregularities in order to increase the probability of rubbing with the toner and to achieve good toner transportability. A blasting process such as alundum abrasive grains or glass beads is performed for forming the rough surface of the convex portion, or a convex portion is formed using conductive particles such as metal oxide particles, graphite, and carbon, for example. It is also possible to suitably form a concave portion using a phenol resin for binding these particles.

Referring to FIG. 2, in the developing container 41, an elastic blade 44 as a developer layer thickness regulating means is supported by a pressing metal plate 48 at a position above the developing sleeve 42. The vicinity of the front end is provided so as to contact the outer peripheral surface of the developing sleeve 42 by surface contact. The elastic blade 44 is configured so that its tip is located in the rotation direction upstream side of the developing sleeve 42, that is, in a so-called counter direction abutting direction.

The elastic blade 44 has a spring elasticity S
A material obtained by injection-forming a rubber material such as urethane or silicone and various elastomers as the elastic member 44b on a thin metal plate 44a such as US or phosphor bronze is preferably used.

An elastic roller 43 serving as a developer supply and stripping means is positioned upstream of the position where the elastic blade 44 abuts on the developing sleeve 42 in the rotational direction of the developing sleeve 42 so as to abut the developing sleeve 42. ,and,
The developing sleeve 42 is supported so as to be rotatable in the same direction (arrow C direction). The elastic roller 43 will be described later in detail.

When the developing device 4 starts the developing operation, the toner is stirred by the rotation of the stirring member 45 in the direction of arrow D,
Further, the sheet is conveyed to the elastic roller 43 side. Further, the toner is conveyed to the vicinity of the developing sleeve 42 by the rotation of the elastic roller 43 in the direction of the arrow C, and the toner carried on the elastic roller 43 at the contact portion between the developing sleeve 42 and the elastic roller 43 is By being rubbed against the developing sleeve 42, it receives triboelectric charging and adheres to the developing sleeve 42.

Thereafter, as the developing sleeve 42 rotates in the direction of arrow B, the toner is sent under pressure of the elastic blade 44, and receives a desired triboelectric charge (triboelectric charge). After being formed, it is conveyed to a developing position which is a portion facing the photosensitive drum 1.

At the developing position, an AC voltage, in which a DC voltage is superimposed, is applied between the photosensitive drum 1 and the developing sleeve 42 by a power supply 49, and the toner on the developing sleeve 42 is changed by the developing bias voltage. 1
It flies upward and selectively adheres to the electrostatic latent image on the surface of the photosensitive drum 1 to form a toner image.

The toner remaining on the surface of the developing sleeve 42 without contributing to the development is changed with the rotation of the developing sleeve 42.
It is transported again to the developing container 41 and collected from the lower part of the developing sleeve 42. A seal member 46 is provided in this collection portion to allow the toner not contributing to the development to pass into the developing container 41 and to allow the toner in the developing container 41 to leak from the lower portion of the developing sleeve 42. To prevent

The toner collected on the developing sleeve 42 in the developing container 41 is applied to the elastic roller 43 and the developing sleeve 42.
Is peeled off from the surface of the developing sleeve 42 at the abutting portion. Most of the toner peeled off at this time is conveyed with the rotation of the elastic roller 43, mixed with the toner contained in the developing container 41, and the charge of the toner is dispersed. At the same time, the rotation of the elastic roller 43 supplies new toner onto the developing sleeve 42, and the operation described above is repeated.

More specifically, in this embodiment, the diameter of the photosensitive drum 1 is 35 mm, and the developing sleeve 42 has a diameter of 16 m.
m, 1.5mm thick aluminum sleeve surface,
A regular blast treatment with glass beads (# 600) is performed, and the surface roughness is determined by a three-point average roughness of JIS B0601.
μm was used. The photosensitive drum 1 has a peripheral speed of 50 mm
/ S, and the developing sleeve 42 was rotated at 80 mm / s, which was slightly faster than the peripheral speed of the photosensitive drum 1.

As shown in FIG. 3, a spacer 47 is provided between the developing sleeve 42 and the photosensitive drum 1 such that a gap X between both ends in the longitudinal direction of the developing sleeve 42 is 300 μm.
Regulated by. The gap between the developing sleeve 43 and the photosensitive drum 1 will be described later in detail.

The developer used in this embodiment is a non-magnetic one-component developer as described above, and contains only non-magnetic toner particles (toner) as the developer. The average particle size (volume average particle size) of the toner was 8 μm. The elastic blade 44 is formed by bonding or molding a polyamide elastomer with a thickness of 1 mm as an elastic member 44b on a thin metal plate 44a made of a phosphor bronze metal having a thickness of 0.1 mm having spring elasticity, The contact pressure against the developing sleeve 42 was 10 g / cm. In this specification, the average particle size of the toner is shown as a weight average particle size.

The weight average particle size of the toner was measured by the following apparatus and method. That is, using a Coulter counter TA-II type (manufactured by Coulter) as a measuring device,
Using an interface (manufactured by Nikkaki) and a CX-1 personal computer (manufactured by Canon) connected to output a number distribution and a volume distribution, a 1% aqueous NaCl solution was prepared using primary sodium chloride as an electrolyte. As a measuring method, 0.1 to 5 ml of a surfactant is added as a dispersing agent to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample was suspended was treated with an ultrasonic disperser for about 1 to 3 minutes, and was then used as an aperture by the Coulter Counter TA-II.
Using a 0 μm aperture, 2 to 4
The particle size distribution of the 0 μm particles was measured, from which the weight average particle size according to the invention was determined.

Here, the linear pressure was measured by sandwiching three SUS thin plates having a known coefficient of friction under pressure contact with an elastic blade.
The center sheet was pulled out with a spring alone, and the pulling force at that time was calculated from the friction coefficient, and the number of grams per unit length was obtained.

In this embodiment, the power supply 4
9, the developing bias voltage applied to the developing sleeve 42 has a frequency of 2000 Hz, a peak-to-peak voltage of 200.
A DC voltage of -400V is superimposed on an AC voltage of 0V,
Further, the surface potential on the photosensitive drum 1 is
An electrostatic latent image is formed at 600 V (non-exposed area, dark area), and an image portion whose charge potential has been attenuated by exposure is set at -150 V (exposed area, light area), and reversal development is performed to attach toner to the exposed area.

Next, the elastic roller 43 will be described in more detail.

As the elastic roller 43, a roller obtained by adhering a foam 43b of polyurethane foam, silicone or the like so as to form a roller on a core metal 43a serving as a rotating shaft can be suitably used. The number is preferably about 50 to 200 cells per inch from the viewpoint of supplying the toner onto the developing sleeve 42. In this embodiment, a polyurethane foam having 75 cells per inch is used.

In this embodiment, the outer diameter of the elastic roller 43 is 1
5 mm, and the nip width is 5 m with respect to the developing sleeve 42.
m in the developing container 41 so that the contact pressure against the developing sleeve 42 becomes 60 g / cm.
The elastic roller 43 is driven to rotate at a peripheral speed of 60 mm / s in the same direction as the developing sleeve 42.

As described above, the present inventors have clarified that the image density unevenness occurs in the longitudinal direction of the developing sleeve 42 due to the bending of the elastic sleeve 42. Therefore, the developing device according to the present invention employs the arrangement of the elastic roller 43 for preventing the bending of the developing sleeve 42. This will be described in detail below.

As shown in FIG. 2, a straight line connecting the rotation center of the photosensitive drum 1 and the rotation center of the developing sleeve 42 is E, and a straight line connecting the rotation center of the elastic roller 43 and the rotation center of the developing sleeve 42 is F. And the angle between the straight line E and the straight line F is α.

In order to prevent the bending of the developing sleeve 42, it is preferable that the angle α is not less than 80 degrees and not more than 100 degrees, and in this embodiment, the angle α is approximately 90 degrees.

An image was formed on 3000 sheets of A4-size recording material P by the image forming apparatus provided with the developing device 4 having the above configuration.

In order to clearly show the operation and effect of the present invention, similar images were formed by changing the angle α to 60 degrees, 120 degrees and 180 degrees as a comparative example. Developing sleeve 4 during image forming operation below
The gap Y (FIG. 3) between the developing sleeve 42 and the photosensitive drum 1 at the center in the longitudinal direction was measured.

At the same time, in the output image at the time when the image forming operation for 3000 sheets is completed, the developing sleeve 42
The image density was evaluated for unevenness (image density unevenness) in the longitudinal direction, that is, in the direction perpendicular to the recording material P conveyance direction.

Table 1 shows the results of the image forming test described above. In addition, as for the image unevenness in Table 1, a case where the image unevenness hardly occurs is represented by (○), a case where the image unevenness occurs is expressed as (×), and a case where the image unevenness occurs significantly is expressed as (XX). .

[0077]

[Table 1]

As shown in Table 1, when the angle α was 90 degrees, image density unevenness in the longitudinal direction of the developing sleeve 42 hardly occurred, and a good image was obtained. At this time, the measured value of the gap Y at the central portion in the longitudinal direction of the developing sleeve is 305.
μm, which is almost the same as the gap X = 300 μm at both ends in the longitudinal direction of the developing sleeve 42 regulated by the spacer 47.

On the other hand, the angle α is 180 degrees (Comparative Example 1), that is, the direction in which the elastic roller 43 presses the developing sleeve 42 (the direction along the straight line F) is directed toward the surface of the photosensitive drum 1 (in the direction of the straight line E). (The direction along), the image density unevenness in the longitudinal direction of the developing sleeve 42 was most remarkable. or,
At this time, the measured value of the gap Y at the central portion in the longitudinal direction of the developing sleeve 42 was 240 μm, and the above-mentioned gap X = 300 μm
It turns out that it is narrower than. For this reason, the image density at the central portion in the longitudinal direction of the developing sleeve 42 was increased, resulting in image density unevenness.

Similarly, when the angle α was 120 degrees (Comparative Example 2), the gap Y was 270 μm, and image density unevenness occurred.

When the angle α is 60 degrees (Comparative Example 3), ie,
If the angle α is less than 90 degrees and the direction in which the elastic roller 43 presses the developing sleeve 42 (the direction along the straight line F) is away from the surface of the photosensitive drum 1 (the direction along the straight line E), the gap Y becomes 330 μm and the developing sleeve 42
The image density at the center in the longitudinal direction is lower than that in Comparative Example 1.

As understood from the above, by setting the angle α to approximately 90 degrees according to the present invention, when the developing sleeve 42 is bent by the contact pressure of the elastic roller 43 with the developing sleeve 42, The bending direction can be made substantially coincident with the circumferential direction of the photosensitive drum 1 at the developing position.
Accordingly, it is possible to make the gap Y between the developing sleeve 42 and the photosensitive drum 1 at the center in the longitudinal direction substantially equal to the gap X at both ends in the longitudinal direction of the developing sleeve 42.

More specifically, in this embodiment, the measured value of the gap Y is slightly larger than the value of the gap X. This is because in the present embodiment, the angle α is strictly 90 degrees, and the bending direction of the developing sleeve 42 is strictly orthogonal to the straight line E connecting the rotation center of the photosensitive drum 1 and the rotation center of the developing sleeve 42. The gap Y is increased by the curvature of one.

Therefore, preferably, by making the angle α slightly larger than 90 degrees, that is, up to about 100 degrees, the gap between the photosensitive drum 1 and the developing sleeve 42 can be made more uniform in the longitudinal direction. Becomes The angle α is
In practice, it has been found that the size can be reduced to about 80 degrees.

The outer diameter of the photosensitive drum 1 and the developing sleeve 4
2, outer diameter and strength, developing sleeve 42 of elastic roller 43
The degree of influence on the gap between the photosensitive drum 1 and the developing sleeve 42 depends on the amount of bending of the developing sleeve 42 and the contact pressure on the developing sleeve 42. Accordingly, although the angle α at which the gap in the longitudinal direction of the developing sleeve 42 can be made most uniform varies depending on the image forming apparatus to be implemented, the angle α
Is set to approximately 90 degrees, it is possible to make the gap in the longitudinal direction substantially uniform for each bending. According to the study by the present inventors, in the image forming apparatus having the configuration of the present embodiment as described above, the angle α is 80 degrees or more.
It was found that in the range of 100 degrees, the gap between the developing sleeve 42 and the photosensitive drum 1 was substantially uniform in the longitudinal direction.

According to the present embodiment, the contact pressure (10 g / cm) of the elastic blade 44 against the developing sleeve 42 is smaller than the contact pressure of the elastic roller 43 against the developing sleeve 42 (60 g / cm). The contact position of the elastic roller 43 is arbitrarily determined from the viewpoint that the influence on the deflection of the developing roller 42 is very small. The elastic blade 44 is brought into contact with the developing sleeve 42 at a point symmetrical position with respect to.

That is, the contact position between the elastic blade 44 and the developing sleeve 42 is determined by the elastic roller 43 and the developing sleeve 4.
The position is 170 ° to 190 ° downstream of the developing sleeve 42 in the rotation direction from the contact position with the developing sleeve 42.

By doing so, the elastic blade 44
The direction of the contact pressure of the developing sleeve 42 with respect to the developing sleeve 42 is a direction that cancels the bending of the developing sleeve 42 due to the contact pressure of the elastic roller 43, so that the gap between the photosensitive drum 1 and the developing sleeve 42 is more evenly arranged in the longitudinal direction. It is possible to do.

As described above, according to the image forming apparatus of the present invention, the direction of bending of the developing sleeve 42 due to the contact pressure of the elastic roller 43 with the developing sleeve 42 is different from the circumferential direction of the photosensitive drum 1 at the developing position. Thus, the gap between the developing sleeve 42 and the photosensitive drum 1 can be made uniform in the longitudinal direction.

Embodiment 2 Since the image forming apparatus of this embodiment is basically the same as that of Embodiment 1, members having the same functions are denoted by the same reference numerals, and detailed description is omitted.

FIG. 4 shows another embodiment near the developing position of the image forming apparatus according to the present invention.

According to this embodiment, the characteristics of the toner used,
Depending on the surface characteristics of the developing sleeve 42 and the like, the toner layer thickness regulating force by the elastic blade 44, that is, the elastic blade 44
It is intended that the present invention can be applied also when it is necessary to increase the contact pressure of the developing sleeve against the developing sleeve.

That is, the developing sleeve 4 of the elastic blade 44
2 was 40 g / cm, and the contact pressure of the elastic roller 43 against the developing sleeve 42 was 60 g, as in the first embodiment.
g / cm. In such a case, the elastic roller 43
The bending of the developing sleeve 42 due to the contact pressure does not become dominant, and it is necessary to consider the influence of the contact pressure of the elastic blade 44.

Therefore, as shown in FIG.
3, a pressing force vector F1 for the developing sleeve 42;
The angle β formed by the resultant vector F3 of the elastic blade 44 and the pressing force vector F2 with respect to the developing sleeve 42 and the straight line G connecting the rotation center of the photosensitive drum 1 and the rotation center of the developing sleeve 42 is approximately 90 degrees. That is, the resultant force vector F3 is configured to be substantially perpendicular to the straight line G.

Thus, when the developing sleeve 42 is bent by the contact pressure of the elastic roller 43 and the elastic blade 44 with the developing sleeve 42, the bending direction is substantially coincident with the circumferential direction of the photosensitive drum 1 at the developing position. Can be done. Accordingly, the gap Y between the developing sleeve 42 and the photosensitive drum 1 at the central portion in the longitudinal direction is defined as
It is possible to make the gap X at both ends in the longitudinal direction substantially equal.

More specifically, in the present embodiment, the angle γ formed by the vector F1 and the straight line G is 80 degrees, and the vector F2 (connects the contact position between the elastic blade 44 and the developing sleeve 42 and the rotation center of the developing sleeve 42). The angle θ between the straight line G and the straight line G was set to 105 degrees. As in the first embodiment, in each image forming apparatus embodying the present invention, the angle β can be adjusted in accordance with the degree of bending of the developing sleeve 42. However, according to the study of the present inventors, the angle β is It is desirable that the angle be 80 degrees or more and 100 degrees or less.

When the frictional force between the elastic roller 43 and the elastic blade 44 against the developing sleeve 42 is large,
Needless to say, it is necessary to determine the angles γ and θ in consideration of this force. The intention of the present inventors is that the direction of the force (F3) applied to the developing sleeve 42 is substantially perpendicular to the straight line G at the developing position where the photosensitive drum 1 and the developing sleeve 42 are opposed to each other. It is.

As described above, according to the image forming apparatus of the present invention, even when the contact pressure of the elastic blade 44 with the developing sleeve 42 is high and the influence of the pressure on the bending of the developing sleeve 42 cannot be ignored. Thus, the bending direction of the developing sleeve 42 caused by both the elastic roller 43 and the elastic blade 44 can be made to substantially coincide with the circumferential direction of the photosensitive drum 1 at the developing position. Therefore, the gap between the photosensitive drum 1 and the developing sleeve 42 can be made uniform in the longitudinal direction.

In the above two embodiments, the developing device 4 is unitized so as to be detachable from the image forming apparatus main body. However, the present invention is not limited to this. 4 is fixed to the image forming apparatus main body,
It is also possible to adopt a configuration in which only toner can be supplied.

For example, as shown in FIG. 6, the photosensitive drum 1, the charging roller, the developing device 4, the cleaning device 8 including the cleaning blade 10 and the waste toner container 11 are collectively unitized by the cover 12, and the image is formed. Process cartridge 2 detachable from the forming apparatus main body
It can be set to 0. In the image forming apparatus main body, mounting means 13 for detachably mounting the process cartridge 20 are provided at, for example, two places in the case of the image forming apparatus of FIG.

That is, the so-called process cartridge in the present specification is a unit in which a charging unit, a developer carrying unit or a cleaning unit and an image carrying unit are integrally formed into a cartridge, and this cartridge is detachable from the main body of the image forming apparatus. Or at least one of a charging unit, a developer carrier, and a cleaning unit and an image carrier are integrally formed as a cartridge so as to be detachable from the image forming apparatus main body. The developer carrier and the image carrier are integrally formed into a cartridge so as to be detachable from the image forming apparatus main body.

[0102]

As described above, according to the present invention,
A developer container for containing a one-component developer as a developer, a rotatable developer carrier extending to an opening of the developer container, and developing on the developer carrier in contact with the surface of the developer carrier; A rotatable developer supply / peeling roller for supplying and peeling the developer, and a developer carrier contacting the developer carrier at a downstream side of the developer supply / peeling roller in the rotation direction of the developer carrier. A developer layer thickness regulating means for regulating the layer thickness of the one-component developer, and a developer carrier for carrying the one-component developer, an image carrier having an electrostatic latent image on the surface; In a developing device for visualizing an electrostatic latent image on an image carrier at an opposite developing position, a first straight line connecting a rotation center of a developer supply and peeling roller and a rotation center of the developer carrier, A second straight line connecting the rotation center of the carrier and the rotation center of the developer carrier is formed. Since the degree (α) is set to be not less than 80 degrees and not more than 100 degrees on the upstream side in the rotation direction of the developer carrier when viewed from the first straight line, the deflection due to the contact pressure of the developer supply and stripping means with respect to the developer carrier. Is substantially matched with the circumferential direction of the image carrier at the developing position, and the gap between the developer carrier and the image carrier can be made uniform in the longitudinal direction. Therefore, the developing device of the present invention, and the process cartridge and the image forming apparatus including the developing device, prevent the generation of the ghost image by reliably performing the toner supply and the peeling of the toner by the peeling unit, and It is possible to prevent the image density from becoming non-uniform in the longitudinal direction of the developer carrier, and to stably obtain a good image having a uniform image density.

Further, according to another aspect of the present invention, the same applies to the case where the contact pressure of the developer layer thickness regulating means with respect to the developer carrying member has a non-negligible effect on the deflection of the developer carrying member. The operation and effect of the present invention can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an embodiment of a developing device according to the present invention and an image forming apparatus including the same.

FIG. 2 is a schematic configuration diagram showing one embodiment of a developing device according to the present invention.

FIG. 3 is a view of the vicinity of a developing position as viewed from above.

FIG. 4 is a schematic sectional view illustrating a developing position of another embodiment of the image forming apparatus according to the present invention.

FIG. 5 is a schematic configuration diagram illustrating an example of a conventional developing device.

FIG. 6 is a schematic configuration diagram illustrating an embodiment of an image forming apparatus according to the present invention, in which a process cartridge is detachable.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photosensitive drum (image carrier) 2 Charging roller (charging means) 3 Optical system 4 Developing device 7 Transfer roller (Transfer means) 8 Cleaning device 9 Fixing device 12 Cover 13 Mounting means 14 Transport means 20 Process cartridge 41 Developing container 42 Development Sleeve (developer carrier) 43 Elastic roller (developer supply and stripping roller) 44 Elastic blade (developer layer thickness regulating blade) 45 Stirring member

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuhisa Tsurugimo 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Yasunari Watanabe 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon F term in reference (reference) 2H071 BA04 BA13 DA06 DA08 DA13 DA15 2H077 AD06 AD13 AD14 AD17 AD31 BA08 BA09 EA11

Claims (23)

[Claims] 1. A developer container for containing a one-component developer as a developer, a rotatable developer carrier extending to an opening of the developer container, and a developer container contacting a surface of the developer carrier. A rotatable developer supply and peeling roller for supplying and peeling the developer on the developer carrier, and the developing device at a downstream side of the developer supply and peeling roller in a direction of rotation of the developer carrier. A developer layer thickness regulating means for abutting on a developer carrier to regulate a layer thickness of the one-component developer on the developer carrier, the developer carrier carrying the one-component developer. Is a developing device that visualizes the electrostatic latent image on the image carrier at a developing position opposite to the image carrier having the electrostatic latent image on the surface, wherein the developer supply and the rotation center of the peeling roller A first straight line connecting the rotation center of the developer carrying member, An angle (α) between a rotation center of the image bearing member and a second straight line connecting the rotation center of the developer bearing member is set at an upstream side in the developer bearing member rotation direction with respect to the first straight line. A developing device having a temperature of not less than 100 degrees and not more than 100 degrees. 2. The developing device according to claim 1, wherein the angle (α) is approximately 90 degrees. 3. The developer layer thickness regulating means contacts the developer carrier at a point symmetrical position with respect to a contact position of the developer supply and stripping roller with the developer carrier. 3. The developing device according to claim 1, wherein: 4. A developer container for containing a one-component developer as a developer, a rotatable developer carrier extending to an opening of the developer container, and a developer container contacting the developer carrier surface. A rotatable developer supply and peeling roller for supplying and peeling the developer on the developer carrier, and the developing device at a downstream side of the developer supply and peeling roller in a direction of rotation of the developer carrier. A developer regulating unit that abuts on a developer carrier to regulate a layer thickness of the one-component developer on the developer carrier, and the developer carrier that carries the one-component developer, In a developing device for visualizing an electrostatic latent image on the image carrier at a developing position opposed to an image carrier having an electrostatic latent image on a surface thereof, the developer carrier of the developer supply and peeling roller is provided. And the developer of the developer layer thickness regulating means. The angle (β) between the resultant vector of the pressing force on the carrier and the straight line connecting the rotation center of the image carrier and the rotation center of the developer carrier is 80 degrees or more, and
A developing device having a temperature of not more than 00 degrees. 5. A combination of a resultant vector of a pressure applied to the developer carrier by the developer layer thickness regulating means and a straight line connecting a rotation center of the image carrier and a rotation center of the developer carrier. The developing device according to claim 4, wherein the angle (β) is approximately 90 degrees. 6. A process cartridge detachably mountable to an image forming apparatus main body, including an image carrier, and a developing device provided with at least a developer carrier, a developer supply / peeling roller, and a developer layer thickness regulating unit. A process unit acting on the image carrier, a first straight line connecting a rotation center of the developer supply and peeling roller and a rotation center of the developer carrier, and a rotation of the image carrier. An angle (α) between a center and a second straight line connecting the rotation center of the developer carrier is 80 degrees or more and 100 degrees or less on the upstream side in the developer carrier rotation direction as viewed from the first straight line. A process cartridge. 7. The process cartridge according to claim 6, wherein the angle (α) is approximately 90 degrees. 8. The developer layer thickness regulating means abuts on the developer carrier at a point symmetrical position with respect to the abutment position of the developer supply and peeling roller on the developer carrier. 8. The process cartridge according to claim 6, wherein: 9. The process cartridge, wherein the developing device as the process means, a charging means or a cleaning means, and the image carrier are integrally formed into a cartridge, and the cartridge is attached to the image forming apparatus main body. The process cartridge according to claim 6, wherein the process cartridge is detachable. 10. The process cartridge comprises a developing device, a charging device, a cleaning device as the process means, and an image carrier integrally formed as a cartridge, and the cartridge is detachably mountable to an image forming apparatus main body. The process cartridge according to any one of claims 6 to 8, wherein 11. A process cartridge detachably mountable to an image forming apparatus main body, including an image carrier, and a developing device provided with at least a developer carrier, a developer supply / peeling roller, and a developer layer thickness regulating unit. A process unit acting on the image carrier, and a pressing force of the developer supply and peeling roller against the developer carrier, and a pressure applied to the developer carrier by the developer layer thickness regulating unit. The angle (β) between the resultant vector of the pressing force and the straight line connecting the rotation center of the image carrier and the rotation center of the developer carrier is 80.
A process cartridge having a temperature of not less than 100 degrees and not more than 100 degrees. 12. A resultant vector of the developer layer thickness regulating means and a pressing force applied to the developer carrier, and a straight line connecting the rotation center of the image carrier and the rotation center of the developer carrier. The process cartridge according to claim 11, wherein the angle (β) is approximately 90 degrees. 13. The process cartridge, wherein the developing device as the process unit, a charging unit or a cleaning unit, and the image carrier are integrally formed into a cartridge, and the cartridge is attached to the image forming apparatus main body. 13. The process cartridge according to claim 11, wherein the process cartridge is detachable. 14. The process cartridge comprises a developing device, a charging device, a cleaning device as the process means, and an image carrier integrally formed as a cartridge, and the cartridge is detachably mountable to an image forming apparatus main body. The process cartridge according to claim 11, wherein: 15. An image forming apparatus in which a process cartridge is detachable and forms an image on a recording material,
(A) an image carrier, and a process unit acting on the image carrier including at least a developer carrier, a developer supply / peeling roller, and a developing device having a developer layer thickness regulating unit. A first straight line connecting the rotation center of the developer supply and stripping roller and the rotation center of the developer carrier, and a first straight line connecting the rotation center of the image carrier and the rotation center of the developer carrier. The angle (α) formed by the second straight line and the second straight line is 8
An image forming apparatus, comprising: mounting means for removably mounting a process cartridge having an angle of 0 degrees or more and 100 degrees or less to an apparatus main body; and (b) conveying means for conveying the recording material. . 16. The image forming apparatus according to claim 15, wherein the angle (α) is approximately 90 degrees. 17. The developer layer thickness regulating means contacts the developer carrier at a point symmetrical position with respect to a contact position of the developer supply and stripping roller with the developer carrier. 17. The image forming apparatus according to claim 15, wherein: 18. The process cartridge, wherein the developing device as the process unit, a charging unit or a cleaning unit, and the image carrier are integrally formed into a cartridge, and the cartridge is attached to the image forming apparatus main body. The image forming apparatus according to claim 15, wherein the image forming apparatus is detachable. 19. The process cartridge is a cartridge in which a developing device, a charging unit, a cleaning unit, and an image carrier as the process unit are integrally formed as a cartridge, and the cartridge is detachably mountable to an image forming apparatus main body. The image forming apparatus according to claim 15, wherein: 20. An image forming apparatus for detachably attaching a process cartridge and forming an image on a recording material,
(A) an image carrier, and a process unit acting on the image carrier including at least a developer carrier, a developer supply / peeling roller, and a developing device having a developer layer thickness regulating unit. The resultant force vector of the pressing force of the developer supply and stripping roller on the developer carrier, the pressing force of the developer layer thickness regulating means on the developer carrier, and the rotation of the image carrier. Mounting means for removably mounting a process cartridge having an angle (β) between a center and a straight line connecting the rotation center of the developer carrying member of 80 ° or more and 100 ° or less to the apparatus main body; b) a conveying means for conveying the recording material. 21. A resultant vector of a force applied to the developer carrier by the developer layer thickness regulating means and a straight line connecting the rotation center of the image carrier and the rotation center of the developer carrier. 21. The image forming apparatus according to claim 20, wherein the angle (β) is approximately 90 degrees. 22. The process cartridge, wherein the developing device as the process unit, a charging unit or a cleaning unit, and the image carrier are integrally formed into a cartridge, and the cartridge is attached to the image forming apparatus main body. 22. The image forming apparatus according to claim 20, wherein the image forming apparatus is detachable. 23. The process cartridge comprises a developing device, a charging device, a cleaning device as the process means, and an image carrier integrally formed as a cartridge, and the cartridge is detachably mountable to an image forming apparatus main body. 22. The image forming apparatus according to claim 20, wherein: