JPH0934247A - Electrostatic latent image developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute a device so that a projection amount from the contact center of a developing roller and a blade which constitutes a developer control means up to the leading end of the blade may come to a prescribed value by forming a contact recessed part whose curvature is almost the same as that of the circumferential surface of the developing roller on one side of the blade. SOLUTION: The developer control means is provided with the blade 46 made of a rigid member which is brought into press-contact with the circumferential surface of the roller 26 of the developing roller 16. The blade 46 is constituted of a sheet-like member, and the contact recessed part 461 is formed on one side of the blade 46 so that it may extend along the circumferential surface of the roller 26 in the width direction. The contact recessed part 461 is formed of a curved surface whose curvature is almost the same as that of the circumferential surface of the roller 26. Since almost the whole surface of the contact recessed part 461 comes into nearly uniform contact with the circumferential surface of the roller 26, the projection amount S from the end part of the contact recessed part 461 up to the leading end of the blade 46 is decided only by the dimension of the blade 46.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic latent image developing apparatus used for developing an electrostatic latent image into a toner image in an image forming machine such as an electrostatic copying machine or a laser printer, and more specifically, An electrostatic device having a developing roller that holds the developer on the surface and conveys it to the developing area, and a regulating member that includes a rigid member that acts on the surface of the developing roller and regulates the amount of the developer retained on the surface. The present invention relates to a latent image developing device.

[0002]

2. Description of the Related Art As is well known, in order to develop an electrostatic latent image into a toner image in an image generator, an electrostatic latent image developing device having a developing roller that is rotationally driven in a predetermined direction is widely used. Have been served. When the developing roller is driven to rotate in a predetermined direction, the developer holding area, the developer amount regulating area, and the developing area can be sequentially moved. In the developer holding region, toner as a developer supplied by an appropriate mode is held on the surface of the developing roller. In the developer amount regulation area, the regulation means acts on the toner as the developer retained on the surface of the developing roller to regulate the toner retained on the surface of the developing roller to a required amount. In the developing area, toner as a developer is applied to the surface of an electrostatic latent image bearing member such as a rotating drum having an electrophotographic photosensitive layer on the peripheral surface to form a toner on the surface of the electrostatic latent image bearing member. The electrostatic latent image is developed into a toner image. In order to achieve good development, the amount of toner retained on the surface of the developing roller is appropriately regulated by the regulating means so that the toner layer retained on the surface of the developing roller has a predetermined thickness and an axial direction. It is important to form the film sufficiently uniformly.

Japanese Patent Publication No. 63-16736 discloses an electrostatic latent image developing device having a regulating means having a blade made of a rubber elastic body made of synthetic rubber such as urethane rubber and silicon rubber. The rubber elastic body constituting the developer regulating means has one surface or the leading edge thereof pressed against the surface of the developing roller to regulate the amount of toner held on the surface of the developing roller to a considerably small amount, and the toner on the surface of the developing roller. To form a thin layer of. Further, a blade of the developer regulating means is constituted by a stainless steel thin plate for spring having a thickness of 0.1 to 0.2 mm, which has been put into practical use. However, in the developer regulating means using an elastic blade such as a rubber elastic body or a stainless thin plate, both ends of the elastic blade are low in rigidity and inferior in regulation force to the central portion, so that they are formed on the surface of the developing roller. The toner layer at both ends is thicker at both ends than the center portion. According to the experiments by the present inventors, when the urethane blade is used, the toner layer at both ends is 3.5 times thicker than the center portion.
It was found that the thickness was about 7.0 μm. As described above, when the elastic blade is used, it is difficult to form the toner layer formed on the surface of the developing roller to have a uniform thickness in the entire axial direction, and thus it is difficult to obtain a uniform image. In addition, the elastic blade has low wear resistance and is not always satisfactory in terms of prolonging its service life.

In order to solve the above problems of the elastic blade, the applicant of the present invention has proposed an invention in which the blade constituting the developer regulating means is formed of a rigid member such as glass.
Proposed as No. 36277. By forming the blade from plate glass, the layer thickness of the toner layer formed on the surface of the developing roller can be uniformly controlled in the width direction, and abrasion resistance is also improved, which is also satisfactory in terms of long life. It became possible.

[0005]

When the blade constituting the developer regulating means is formed of a rigid member such as glass, the amount of protrusion from the contact center between the developing roller and the blade to the tip of the blade. As a result, the layer thickness of the toner layer formed on the surface of the developing roller changes. That is, when the amount of protrusion is longer than a predetermined value, the toner that adheres to and moves on the surface of the developing roller has an area on one side of the blade that is larger than the predetermined value, so that the force that acts in the direction of escaping the blade increases. The toner layer formed on the surface of the developing roller becomes thick. On the other hand, if the amount of protrusion is shorter than a predetermined value, the toner that adheres to and moves on the surface of the developing roller has an area on one side of the blade smaller than a predetermined value, so that the force that acts in the direction of letting the blade decrease decreases, The thickness of the toner layer formed on the surface of the developing roller becomes thin.
However, in the blade support structure disclosed in the above publication, the protrusion amount cannot be adjusted after the blade is assembled, and therefore, the accuracy of the protrusion amount depends on the manufacturing precision of each component of the blade and the support structure. Is decided. However, increasing the manufacturing accuracy of the blade and the above-mentioned components unnecessarily increases the cost.

The present invention has been made in view of the above facts, and its main technical problem is to control only the manufacturing accuracy of the blade so that one side of the blade is in contact with the peripheral surface of the developing roller. It is an object of the present invention to provide an electrostatic latent image developing device provided with a developer regulating means that can always set the above-mentioned protrusion amount to a predetermined value.

[0007]

In order to solve the above-mentioned main technical problems, according to the present invention, a developing housing,
A developing roller for holding the developer on the surface in the developer holding area and conveying the held developer to the developing area and applying it to the electrostatic latent image; and the developer holding area. A regulating means having a blade made of a rigid member that acts on the peripheral surface of the developing roller in the developer regulating area located between the developing area and regulates the amount of the developer retained on the surface, and a regulating means of the blade. In an electrostatic latent image developing device having an elastic urging means for pressing one surface in a direction in which it is pressed against the peripheral surface of the developing roller, a blade made of a rigid member constituting the regulating means is provided on one surface of the developing roller. An electrostatic latent image developing device is provided, which is provided with a contact recess having substantially the same curvature as the peripheral surface.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an electrostatic latent image developing device constituted according to the present invention will be described below in more detail with reference to the accompanying drawings.

FIG. 1 shows an image generator equipped with an electrostatic latent image developing device constructed according to the present invention. The illustrated image generator includes a rotary drum 1 as an image carrier having a photosensitive layer on its peripheral surface. The rotary drum 1 is rotatably mounted in a machine body housing (not shown) by a rotary shaft 2. Around the rotating drum 1 which is rotated in the direction indicated by the arrow 3, a charging corona discharger 4 for sequentially charging the photosensitive layer of the rotating drum 1 to a specific polarity in the direction of rotation, and the charging corona discharger. A laser optical device 5 as an exposing means for forming an electrostatic latent image on the photosensitive layer of the rotary drum 1 which is charged with a specific polarity by an electrostatic latent image formed by the laser light emitted from the optical device 5. An electrostatic latent image developing device 6 for developing a toner image, a transfer corona discharger 7, a peeling corona discharger 8, a cleaning device 9, and a charge eliminating lamp 10 are provided.

The developing device 6 is provided with a developing housing 12 which can be made of synthetic resin. Inside the developing housing 12, a developing roller 16, a supplying means 18, an agitating means 20 and a regulating means 22 are provided. It is arranged. Further, although not shown, a toner cartridge containing toner is mounted on the developing housing 12.

The developing roller 16 is the developing housing 1 described above.
It includes a rotary shaft 24 rotatably mounted between the two side walls and a roller 26 fixed to the rotary shaft 24.
The rotating shaft 24 can be formed of a suitable metal material such as stainless steel. The roller 26 is made of a relatively soft and conductive material, for example, a conductive solid rubber such as urethane rubber. The roller 26 has an Asker C hardness of 60 to 85 in the illustrated embodiment.
The volume resistance of the roller 26 is set to about 10 ^{6 to} 10 ⁹ Ω · cm. The roller 26 of the developing roller 16 configured as described above is exposed through an opening formed in the developing housing 12 and is positioned to face the rotary drum 1. The peripheral surface of the roller 26 that constitutes the developing roller 16 is
It is pressed against the peripheral surface of the rotary drum 1, and the peripheral surface of the roller 26 is slightly elastically compressed in the pressed region. The rotating shaft 24 of the developing roller 16 is continuously driven to rotate in a direction indicated by an arrow 28 in FIG. By the above rotation of the rotary shaft 24, the roller 26 is also continuously driven to rotate in the direction indicated by the arrow 28, and the peripheral surface of the roller 26 is sequentially conveyed through the developer holding area 30, the developer regulating area 32 and the developing area 34. It

The supply means 18 includes a rotary shaft 36 rotatably mounted between both side walls of the developing housing 12.
An auxiliary roller 38 fixed to the rotating shaft 36 is included. The auxiliary roller 38 is made of a foam material such as foam silicon or foam urethane. The auxiliary roller 38 is pressed against the roller 26 of the developing roller 16. The hardness of the foam forming the auxiliary roller 38 is considerably smaller than the hardness of the roller 26 (for example, the Asker C hardness is about 35), and the auxiliary roller 38 is pressed against the roller 26, so that the auxiliary roller 38 becomes 0 It is desirable to be elastically compressed by about 0.15 to 0.25 mm. This auxiliary roller 38 is continuously driven to rotate in the direction indicated by arrow 39 in FIG. The stirring means 20 is the developing housing 12
And a stirring member 42 fixed to the rotating shaft 40.
It is continuously driven to rotate in a direction indicated by an arrow 44 in FIG. 1 by a driving means (not shown).

Next, the regulating means 22 will be described with reference to FIGS. 2 and 3. The regulating means 22 includes a blade 46 made of a rigid member that is pressed against the peripheral surface of the roller 26 of the developing roller 16, and an elastic biasing means 47 that presses one surface of the blade 46 in the direction of pressing against the peripheral surface of the roller 26. It has and.

The blade 46 made of the rigid member is made of a plate-shaped member, and one side thereof (that is, the surface which is pressed against the peripheral surface of the roller 26) extends in the width direction (in FIG. 1) along the peripheral surface of the roller 26. A contact recess 461 extending in the direction perpendicular to the paper surface) is formed. The contact recess 461 is
It is formed by a curved surface having a curvature that is substantially the same as the curvature of the peripheral surface of the roller 26 that constitutes the developing roller 16. The amount of protrusion (S) from the end of the contact recess 461 to the tip of the blade 46 varies depending on the diameter of the developing roller 16, but is 0.1.
It is set to 4.0 mm. In addition, the contact recess 46
The circumferential length of 1 also varies depending on the diameter of the developing roller 16, but is set to 1.0 to 20.0 mm. The surface roughness of the curved surface forming the contact concave portion 461 is sufficiently small, and the center line average roughness Ra defined by JIS B 0601 is 6.00 or less, particularly 0.20 or less, and particularly preferably 0.
It is preferably 02 or less. If the surface roughness of the one surface of the blade 46 becomes excessive, the surface of the toner layer formed on the peripheral surface of the roller 26 constituting the developing roller 16 is not sufficiently flattened and tends to be non-uniform. There is. Therefore, a commercially available sheet glass is used as a suitable rigid material having a sufficiently small surface roughness and high hardness and abrasion resistance even though the blade 46 can be formed relatively inexpensively. Can be mentioned. The plate glass may have a thickness of about 3 mm. If it is desired to apply the required voltage to the blade 46 to control the charging characteristics of the toner, a conductive coating can be applied to one side of the sheet glass. As the plate glass having a conductive coating on one surface, a plate glass commercially available under the trade name "Nesa glass" can be conveniently used. Instead of the plate glass, the blade 46 may be made of a rigid member made of an appropriate metal plate such as stainless steel. When assembled, the blade 46 configured as described above has its tip end surface brought into contact with the support portion 121 provided on the mounting portion 120 of the developing housing 12.

The elastic urging means 47 presses the other surface of the blade 46 against the pressing member 471 and a plurality of pressing members 471 press the one surface of the blade 46 against the peripheral surface of the roller 26 through the pressing member 471. The compression coil spring 472 is provided. The pressing member 472 is made of a stainless steel plate having a thickness of about 2 mm, has substantially the same length as the blade 46 corresponding to the length of the blade 46 in the width direction, and has two guiding long holes 471a, 471a. In the illustrated embodiment, two support protrusions 471b and 471b are formed on the rear end surface of the support protrusion. The pressing member 471 thus configured is fitted into the through hole 122 formed in the mounting portion 120 of the developing housing 12, and its front end face, that is, the abutment face 471c contacts the other face of the blade 46. Be punished. The pressing member 471 is fitted into the through hole 122 formed in the mounting portion 120 of the developing housing 12, and the mounting portion 120 of the developing housing 12 is described.
The guide bolts 473, 473 screwed onto
By inserting the two elongated holes 471a and 471a formed in No. 1 respectively, the movement of the pressing member 471 is guided. The plurality of (two in the illustrated embodiment) compression coil springs 472 and 472 have one end fitted to support protrusions 471b and 471b formed on the rear end surface of the pressing member 471 and the other ends thereof. Support protrusions 123, 123 formed on the developing housing 12
Respectively, and presses one side of the blade 46 in the direction of pressing against the peripheral surface of the roller 26 via the pressing member 471. The pressing force of the blade 46 against the peripheral surface of the roller 26 of the developing roller 16 can be appropriately set according to the thickness of the toner layer to be formed on the peripheral surface of the roller 26. When the pressure contact force increases, the thickness of the developer layer formed on the peripheral surface of the roller 26 decreases. On the other hand, if the pressure contact force becomes excessively large, smooth rotation of the roller 26 tends to be impeded. In the developing mode in the illustrated embodiment, the thickness of the toner layer formed on the peripheral surface of the roller 26 is usually about 20 to 30 μm, and in order to properly form the developer layer having such a thickness. The blade 46 may be brought into pressure contact with the circumferential surface of the roller 26 at a linear pressure (pressure per unit length in the width direction) of 4 to 50 g / cm.

The electrostatic latent image developing device according to the embodiment shown in FIGS. 1 to 3 is configured as described above, and its operation will be described below. When the operation of the electrostatic latent image developing device is started, the roller 26 of the developing roller 16, the auxiliary roller 38 of the supply means 18, and the stirring means 20 are rotationally driven in the directions indicated by arrows by driving means not shown. The roller 26 of the developer roller 16 is continuously driven to rotate in the direction shown by the arrow 28, and the supplying means 1 is provided in the developer holding area 30.
8 acts on the roller 26 to separate the toner held on the peripheral surface of the roller 26 up to that time from the roller 26, and the toner is newly supplied to the peripheral surface of the roller 26. In the developer regulation area 32, the blade 46 of the regulation means 22 acts on the developer retained on the peripheral surface of the roller 26 to regulate the toner retained on the peripheral surface of the roller 26 to a required amount and reduce the toner. Form in layers. In order to make the thickness of the toner layer formed on the peripheral surface of the roller 26 a predetermined amount, the protrusion amount from the contact end of the blade 46 constituting the regulating means 22 with the roller 26 to the tip of the blade 46 is set. It is important to maintain the predetermined value, but in the illustrated embodiment, a contact recess 461 extending in the width direction along the peripheral surface of the roller 26 is formed on one surface of the blade 46 that constitutes the regulating means 22. Since the contact recess 461 is formed by a curved surface having substantially the same curvature as the peripheral surface of the roller 26 constituting the developing roller 16, the contact recess 4 is formed.
Since substantially the entire surface of 61 contacts the peripheral surface of the roller 26 substantially uniformly, the amount of protrusion (S) from the contact end of the blade 46 with the roller 26 to the tip of the blade 46 is determined by the size of only the blade 46. Therefore, by controlling the manufacturing accuracy of the blade 46, the above-mentioned protrusion amount (S) can always be maintained at a predetermined value, and the layer pressure of the toner layer formed on the peripheral surface of the roller 26 can be maintained within a predetermined range. be able to. The contact concave portion 461 of the blade 46 is the roller 2
Since a contact is made with a curved surface having substantially the same curvature as that of the peripheral surface of 6, it is possible to form a thin toner layer with a small pressing force,
Therefore, the driving torque of the developing roller 16 can be reduced. Further, since the spring force of the compression coil springs 472 and 472 forming the elastic biasing means 47 acts on the blade 46 via the pressing member 471, the blade 46.
Is not affected by individual variations of the coil spring itself, and a uniform pressing force acts on the blade 46 in the entire width direction. Therefore, the toner layer formed on the surface of the roller 26 of the developing roller 16 can be made uniform. Next, in the developing area 34, a developer is applied to the electrostatic latent image on the electrostatic photoconductor disposed on the peripheral surface of the rotary drum 1 to develop the electrostatic latent image into a toner image. . For example, the electrostatic latent image has a non-image area charged to about + 700V and an image area charged to about + 120V, and toner is attached to the image area (so-called reversal development). The rotary drum 1 is continuously driven to rotate in the direction indicated by the arrow 3 in FIG. 1, so that the peripheral surface of the rotary drum 1 and the peripheral surface of the roller 26 of the developing roller 16 are moved in the same direction in the developing zone 34. . The moving speed V2 of the peripheral surface of the roller 26 is set to be slightly higher than the moving speed V1 of the peripheral surface of the rotating drum 1, and 1.2V1 ≦
It is preferable that V2 ≦ 2.2V1. In this case, sufficient toner is conveyed to the developing area 34 by the roller 26, and the toner is once attached to the non-image portion of the electrostatic latent image by the sliding action of the peripheral surface of the roller 26 against the peripheral surface of the rotary drum 1. The toner is properly peeled off, and thus a good toner image having an appropriate development density and no fog can be obtained. As the developer, the volume average particle diameter (V
ol. 50%: toner having a volume average particle size or less and toner having a volume average particle size or more have the same volume) of 8.0 to 1
A developer consisting of only toner having a volume resistance of about 2.0 μm and 10 ⁸ Ω · cm or more is preferably used.

[0017]

In the electrostatic latent image developing device according to the present invention, the blade made of a rigid member, which constitutes a regulating means for regulating the amount of the developer held on the surface of the developing roller by one side, is Since the contact concave portion having substantially the same curvature as that of the peripheral surface of the developing roller is provided, since the substantially entire surface of the contact concave portion contacts the peripheral surface of the roller substantially uniformly, from the contact end of the blade with the roller to the tip of the blade. The amount of protrusion is determined by the size of the blade only. Therefore, by controlling the manufacturing precision of the blade, it is possible to always maintain the above-mentioned protrusion amount at a predetermined value, and it is possible to maintain the layer pressure of the toner layer formed on the peripheral surface of the roller within a predetermined range. Since the contact concave portion of the blade contacts the peripheral surface of the roller with a curved surface having substantially the same curvature, the toner layer can be formed with a small pressing force, and therefore, the driving torque of the developing roller can be reduced. Further, as described above, since the contact between the blade and the roller is a surface contact due to the curved surface, the surface pressure is small, so that the deformation of the developing roller is reduced and the defective formation of the toner layer caused by the deformation of the developing roller is obviated. Can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an image generator equipped with an electrostatic latent image developing device configured according to the present invention.

FIG. 2 is an enlarged explanatory view showing a relationship between a developing roller and a regulating unit which constitute the electrostatic latent image developing device shown in FIG.

FIG. 3 is a perspective view of a main part of a regulation unit and an elastic biasing unit that form the electrostatic latent image developing device shown in FIG.

[Explanation of symbols]

 1: Rotating drum 4: Corona discharger for charging 5: Laser optical part 6: Electrostatic latent image developing device 7: Corona discharger for transfer 8: Corona discharger for peeling 9: Cleaning device 10: Static elimination lamp 16: Development roller 18: Supply Means 20: Stirring Means 22: Regulation Means 26: Developing Roller Rollers 30: Developer Holding Area 32: Developer Regulation Area 34: Development Area 38: Supply Means Auxiliary Rollers 46: Blades 47: Elastic Energizing Means 461: Contact concave portion 471: Pressing member 472: Compression coil spring 473: Guide bolt

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahisa Nakaue 1-22-28 Tamazo, Chuo-ku, Osaka City Mita Engineering Co., Ltd. Within Mita Engineering Co., Ltd.

Claims (1)

[Claims] 1. A developing housing, and a developer for holding a developer on a surface in a developer holding area provided in the developing housing and conveying the held developer to the developing area to apply it to an electrostatic latent image. A blade comprising a roller and a rigid member that acts on the peripheral surface of the developing roller in a developer regulating area located between the developer retaining area and the developing area to regulate the amount of developer retained on the surface. In the electrostatic latent image developing device, which comprises a regulating means provided with the elastic biasing means for pressing one surface of the blade in a direction of pressing against the peripheral surface of the developing roller, a rigid member constituting the regulating means is provided. The electrostatic latent image developing device is characterized in that the blade is provided on one surface with a contact recess having substantially the same curvature as the peripheral surface of the developing roller.