JPS6235097Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is an electrostatic latent image developing device, more specifically,
The present invention relates to an electrostatic latent image developing device using a one-component developer consisting only of toner particles capable of retaining an electric charge.

An electrostatic latent image developing device used in an electrostatic copying machine or the like to apply toner particles to an electrostatic latent image to make it a developed image has the following characteristics in terms of the developer used: (1) carrier particles and toner particles; (2) A device that uses a so-called two-component developer consisting of (2) toner particles, and a device that uses a so-called one-component developer that consists only of toner particles. The device further includes:
(2-1) A type of device that uses a one-component developer consisting only of relatively conductive toner particles, and (2-
2) devices that use a one-component developer consisting only of toner particles that are relatively insulating and capable of retaining an electric charge;

Therefore, in the above-mentioned type (1), in order to stably perform good development, the ratio of carrier particles to toner particles must always be maintained at a required value. There are problems that are relatively difficult to solve, such as the need to appropriately replenish toner particles as the toner particles are consumed in the process. Also,
In the device of type (2-1) above, the developer is held on the surface of the developer holding member, and as long as the developer is carried to the development area and comes into contact with the electrostatic latent image, the developer, that is, the developer is transferred to the electrostatic latent image. The advantage is that the toner particles can be deposited as desired and therefore do not require any special treatment, such as charging the toner particles prior to contacting the electrostatic latent image; Because of its electrical conductivity, it is relatively difficult to successfully transfer a toner image onto a transfer member in, for example, a toner image transfer type electrostatic copying machine.

Therefore, in recent years, electrostatic latent image developing apparatuses of the type (2-2) above, that is, a type that uses a one-component developer consisting only of toner particles that are relatively insulating and capable of retaining electric charge, have been developed. tends to be used conveniently.

As an electrostatic latent image developing device of the type (2-2) above, Japanese Patent Application No. 1983-29629 (filed date: March 8, 1980, title of invention: Electrostatic A developer having a surface that is moved through an endless path of travel, generally in the form of a roll or an endless belt, such as the electrostatic latent image developer disclosed in the specification and drawings of Latent Image Development Apparatus. A one-component developer consisting of a developer holding member and toner particles capable of retaining an electric charge is accommodated, and the developer is passed through an opening formed in a portion facing a part of the movement path. a developer container to be supplied to the surface of the holding member, and a downstream edge of the opening of the developer container when viewed in the moving direction of the surface of the developer holding member is made of a material having at least a portion of elasticity. An electrostatic latent image developing device of the type in which a charging member is disposed and whose free edge is brought into pressure contact with the surface of the developer holding member is preferably used. In such an electrostatic latent image developing device, the developer supplied from the developer container through its opening to the surface of the developer holding member and held there is charged to the required amount by the action of the free edge of the charging member. The amount (that is, the required layer thickness) is regulated, and the developer is triboelectrically charged, and then, as the surface of the developer retaining member moves, it is transported to the development area and applied to the electrostatic latent image to be developed.

Therefore, in the electrostatic latent image developing device as described above, in order to perform good development, the developer that is brought into contact with the surface of the developer holding member through the layer of developer held on the surface of the developer holding member is required to perform good development. The width of the mutual contact area (that is, the development area) between the surface of the agent holding member and the surface on which the electrostatic latent image to be developed is formed is made sufficiently large, and the mutual contact between the two surfaces is made as uniform as possible. It is important to make it a reality. In order to satisfy these requirements, especially when the developer holding member is in the form of a roll, the hardness of at least the surface layer of the developer holding member must be sufficiently low (measurement method according to JIS standard K-2808). hardness at 15
It is important to keep the angle between 60 degrees and 60 degrees.

On the other hand, as described in the specification of the above-mentioned Japanese Patent Application No. 55-29629, the surface of the developer holding member must be able to reliably hold the developer and have a specific resistance value of a certain value. (typically 10 ³ Ω
- cm) or more, and in order to satisfy such conditions, the weight ratio must be 10
It is advantageous to form the surface layer of the developer retaining member with a material that is flexible and has excellent recovery properties, such as a material containing silicone rubber in an amount of % or more.

However, when the hardness of the above-mentioned materials suitable for forming the surface layer of the developer holding member is sufficiently lowered, the ratio of the materials is generally lowered due to the ratio of the compounded substances required to lower the hardness. The resistance becomes considerably high (e.g., greater than 10 ¹³ Ω-cm). and,
When the resistivity of the above-mentioned material, and therefore the resistivity of the surface layer of the developer holding member, reaches a fairly high value, for example, 10 ¹³ Ω-cm or more, (a) the action of the free edge of the charging member causes toner particles to be It is relatively difficult to achieve sufficient triboelectrification (because if the specific resistance of the surface layer of the developer holding member is relatively low, the amount of oxidation that exists on the surface of the developer holding member during triboelectrification is relatively low). When the toner particles in the surface region of the toner particle layer are charged, relatively strong lines of electric force are generated that extend from the charged toner particles to the surface of the developer holding member through the toner particle layer. Therefore, charging of the toner particles in the entire toner particle layer is promoted, but as the resistivity of the surface layer of the developer holding member increases, the electric lines of force generally become weaker. ) Undesirable edge effects occur in the developed image (because when the resistivity of the surface layer of the developer holding member increases, the charge or potential of the electrostatic latent image to be developed causes This is because the lines of electric force generated between the electrostatic latent image and the surface of the developer holding member tend to be weak.

The present invention has been developed in view of the above facts, and its main purpose is to prevent the problems and defects described in (a) and (b) from occurring even when the surface layer of the developer holding member has a considerably high resistivity. An object of the present invention is to provide an improved electrostatic latent image developing device that can reliably and easily avoid the above problems.

As a result of extensive research and experiments, the inventor of the present invention has found that, first, if the thickness of the developer layer held on the surface of the developer holding member is made extremely thin, from 10 to 50 μm, the above ( It has been found that the problems and defects described in (a) and (b) can be reliably avoided. Second, the hardness of at least the surface layer of the developer holding member is sufficiently low (JIS standard K-
Hardness measured by 2808 (approximately 15 to 60 degrees)
In this case, it has conventionally been impossible or extremely difficult to make the thickness of the developer layer held on the surface of the developer holding member extremely thin as required.
The charging member is arranged so that at least the leading end of the charging member extends downstream at an angle of 0 degrees to 90 degrees when viewed in the moving direction of the surface of the developer holding member with respect to the normal to the surface of the developer holding member. If the free edge of the charging member is pressed against the surface of the developer holding member with a pressing force of 80 to 500 g/cm, the developer can be easily and stably held on the surface of the developer holding member. It has been found that the thickness of the layer can be made extremely thin as required.

Based on the above recognition discovered by the present inventors, the present invention provides a developer retaining member having a surface that can be moved through an endless movement path, and a developer holding member that is composed only of toner particles capable of retaining electric charge. a developer container containing a component-based developer and supplying the developer to the surface of the developer holding member through an opening formed in a portion facing a part of the movement path; At the downstream edge of the opening of the container as viewed in the moving direction of the surface of the developer holding member,
In an electrostatic latent image developing device of the type in which a charging member is disposed, at least a portion of which is made of an elastic material and whose free edge is brought into pressure contact with the surface of the developer holding member; The surface layer having a thickness of at least 100μ has a hardness of 15 to 60 degrees as measured according to JIS standard K-2808, and at least the tip of the charging member is aligned with the normal to the surface of the developer holding member. On the other hand, the surface of the developer holding member extends downstream at an angle α of 0 degrees to 90 degrees when viewed in the moving direction, and the free edge of the charging member has a pressing force of 80 to 500 g/cm. The thickness of the layer of developer retained on the surface of the developer holding member is approximately 10 to 10 mm due to the action of the free edge of the charging member.
Provided is an electrostatic latent image developing device characterized in that: limited to 50μ.

Hereinafter, preferred embodiments of an electrostatic latent image developing device constructed in accordance with the present invention will be described in more detail with reference to the accompanying drawings.

To outline the overall structure of the illustrated electrostatic latent image developing device with reference to FIG. ing.

The developer holding member 4 may be of any form, such as an endless belt, as is well known to those skilled in the art, as long as its surface capable of holding the developer is of such form that it can be moved through an endless travel path. However, in the illustrated example, the roller 10 is rotated in the direction shown by the arrow 8 (therefore, the surface thereof is rotated by the rotation of the roller 10 in the direction shown by the arrow 8). , through a circular travel path defined by the circumferential surface of roller 10).

The developer container 6 accommodating the developer 14 is located at a portion of the surface of the developer holding member 4 that faces a portion of the movement path, thus facing a portion of the circumferential surface of the roller 10 in the illustrated example. Opening 12 formed in the part
has. A charging member 22 is disposed at the downstream edge of the opening 12 when viewed in the direction indicated by the arrow 8 on the surface of the developer holding member 4 . In addition, the developer container 6
A peeling member 32 is provided in the area within the opening 12 for rubbing the surface of the developer holding member 4 and peeling off the developer 14 adhered to or held there from the surface of the developer holding member 4. It is preferable that the

In the electrostatic latent image developing device 2 as described above, the developer 14 contained in the developer container 6 is
is held in contact with the surface of the developer holding member 4 through the opening 12. Then, the developer holding member 4
As will be explained in detail later, the thickness of the developer 14 held on the surface of the developer 14 is regulated as required by the action of the charging member 22, and it is triboelectrically charged. The developer 14, which is held on the surface of the developer holding member 4 and whose thickness is regulated as required and is triboelectrically charged, is held on the surface of the developer holding member 4.
is conveyed to the development zone 16 by movement of the surface thereof, and thus, in the illustrated embodiment, rotation of the roller 10 in the direction indicated by arrow 8. On the other hand, in the development area 16, a suitable electrostatic latent image forming member 18, on the surface of which is formed an electrostatic latent image to be developed, is continuously moved, for example, in the direction indicated by an arrow 20. Thus, in the development area 16, the developer holding member 4
The developer (toner particles) held on the surface of the electrostatic latent image is attached to the surface of the electrostatic latent image forming member 18 according to the potential or charge of the electrostatic latent image, and the electrostatic latent image is developed (toner image). The image is then developed. The developer 14 that remains on the surface of the developer holding member 4 without being attached to the surface of the electrostatic latent image forming member 18 in the developing area 16 accompanies the movement of the surface of the developer holding member 4. The toner is transported again to the area of the opening 12 of the developer container 6, where it is once peeled off from the surface of the developer holding member 4 by the action of the peeling member 32.

Each component of the electrostatic latent image developing device 2 will be described in more detail below.

First of all, the developer 14 used, that is, the developer 14 contained in the developer container 6 will be explained. The developer 14 can be charged by the action of the charging member 22. It is important to use a one-component developer consisting only of toner particles that are capable of retaining a charge. The toner particles themselves capable of retaining an electric charge are known as relatively insulating toner particles, but in the electrostatic latent image developing device 2 according to the present invention, the toner particles capable of retaining an electric charge are 10 ¹² Ω-cm or more, particularly 10 ¹⁴ Ω-cm or more. A one-component developer consisting only of toner particles having a resistivity of Ω-cm or more is preferably used. In addition, toner particles constituting a one-component developer preferably have a small particle size and a large specific surface area so that they can be easily and quickly charged to a saturation charge amount. 5μ to 30μ, especially 20μ
Below, those with a diameter of 15μ or less are particularly preferred.

Next, the developer holding member 4 will be explained.
As already mentioned, in order to perform good development in the electrostatic latent image developing device 2, the surface of the developer holding member 4 must be brought into contact with the surface of the developer holding member 4 through the layer of the developer 14 in the developing area 16. The width of the mutual contact area (i.e., development area) between the surface of the developer holding member 4 and the electrostatic latent image forming member 18 on which the electrostatic latent image to be developed is formed is made sufficiently large; It is important that the mutual contact between the two surfaces be as uniform as possible. For this purpose, it is important to make the hardness of at least the surface layer of the developer holding member 4 sufficiently low. On the other hand, if the hardness of the surface layer of the developer holding member 4 is excessively reduced, the free edge of the charging member 22 pressed against the surface of the developer holding member 4 will cause the developer holding member 4 to Problems arise, such as the surface being significantly damaged in a short period of time. Therefore, the developer holding member 4 has a thickness of 100 μm.
It is important that the surface layer has a hardness of 15 to 60 degrees as measured by the JIS standard K-2808.

The hardness of the surface layer is made to fall within the required range, and the required form (for example, the roll form as shown in FIG. 1,
In order to fabricate the developer holding member 4 with sufficient precision and ease (in the form of a belt), first, a metal support base of the desired shape is formed from a suitable metal material such as aluminum, and then this metal support base is formed. It is preferable that a surface layer made of a material having a hardness within a required range be bonded to the surface of the metal support base, for example, with an adhesive. As the surface layer, a material containing 10% or more of silicone rubber by weight is preferably used as a material that is flexible and has excellent restorability. Since silicone rubber is a material with a fairly high specific resistance, it is possible to mix a resistance control agent such as carbon powder or aluminum powder into it to lower the specific resistance of the surface layer, but in general, the amount of resistance control agent mixed is It should be noted that as the hardness of the surface layer increases, the hardness of the surface layer increases accordingly.

The form of the developer holding member 4 itself may be any form as long as the surface holding the developer 14 can be moved through an endless movement path, as described above, but if the size of the device From the viewpoint of ease of design and manufacture, it is preferable to use a roller-shaped roller, especially a hollow roller 10 as shown in FIG. 1, which is made hollow to reduce weight. be. When the developer holding member 4 is composed of a roller 10, the surface of the electrostatic latent image forming member 18 is moved in the direction of an arrow 20 in the developing area 16, as shown in FIG. It is preferable to rotate the roller 10 in the direction shown by the arrow 8 so that the surface of the developer holding member 4 is moved in the same direction as the direction shown in FIG. When rotating the roller 10 in the opposite direction to the direction indicated by the arrow 8,
A so-called reservoir of the developer 14 is generated on the downstream side of the developing area 16 when viewed in the direction of movement of the electrostatic latent image forming member 18 shown by the arrow 20, and after passing through the developing area 16, the surface of the electrostatic latent image forming member 18 is There is a tendency for the developer 14 to come into contact with the reservoir of the developer 14, and as a result, the developer 14 falls onto the surface of the electrostatic latent image forming member 18 after development, causing so-called background stains on the developed image (toner image). tends to occur. Further, the surface of the roller 10 may be moved at a speed of 0.8 to 15 times the moving speed of the surface of the electrostatic latent image forming member 18.
In particular, it is preferable to rotate the roller 10 at a rotational speed that is 1 to 10 times faster. The moving speed of the surface of the roller 10 is determined by the electrostatic latent image forming member 18.
If it is smaller than 0.8 times the moving speed of the surface of
The sharpness of the developed image (toner image) decreases and an insufficient development phenomenon occurs, and conversely, the moving speed of the surface of the roller 10 is set to be higher than 15 times the moving speed of the surface of the electrostatic latent image forming member 18. As a result, the sharpness of the developed image (toner image) decreases and scumming occurs.

Next, the charging member 22 will be described. The charging member 22 disposed at the downstream edge of the opening 12 of the developer container 6 is made of an elastic material at least in part (in the illustrated case, the entirety). , its free edge 22a is brought into pressure contact with the surface of the developer holding member 4. Such a charging member 22 may be formed integrally with the main body 24 of the developer container 6, but it may be formed separately from the main body 24, which may be formed from an appropriate synthetic resin plate or metal plate, and its base may be formed integrally with the main body 24. 22b is conveniently secured to the body 24.
The charging member 22 can be made of any elastic material, but from the viewpoint of its function of acting on the developer 14 held on the surface of the developer holding member 4 to charge it, the above-mentioned material is suitable. It is desirable to form the developer holding member 4 from a material having a resistivity smaller than that of the surface of the developer holding member 4. Suitable materials for forming charging member 22 may include metallic materials such as phosphor bronze, spring steel, molybdenum, tungsten, or aluminum.
When forming the charging member 22 from a metal material,
It is preferable to perform heat treatment or anodic oxidation treatment to form an oxide film on the surface to increase corrosion resistance, abrasion resistance, etc. The charging member 22 is made of a relatively low resistance synthetic resin material instead of the metal material as described above.
However, in this case, it is important to select a synthetic resin material with sufficient elasticity and mechanical strength.

The charging member 22 as described above, when the surface of the developer holding member 4 moves in the direction indicated by the arrow 8,
The developer 1 is held in contact with the surface of the developer holding member 4 at the opening 12 of the developer container 6.
4 to triboelectrically charge the developer 14. The charging polarity of the developer 14 due to the triboelectric charging action of the charging member 22 is determined by the interrelationship in the triboelectric series of the material of the developer 14 and the material of the charging member 22, as is well known to those skilled in the art. The charging member 22 is
In addition to triboelectrically charging the developer 14, there is also a so-called spike length setting function that regulates the thickness of the layer of the developer 14 held on the surface of the developer holding member 4 and transported to the development area 16 to a required value. carry out.

As mentioned above, when the surface layer of the developer holding member 4 is formed of a material that is flexible and has excellent recovery properties, such as a material containing 10% or more of silicone rubber by weight, this surface layer The hardness of the layer is within a sufficiently low range as described above, that is, JIS standard K-2808.
When the hardness is 15 to 60 degrees using the measurement method according to the above method, the specific resistance of the surface layer generally becomes a fairly high value of 10 ¹³ Ω-cm or more. When the specific resistance of the surface layer of the developer holding member 4 is a fairly high value of 10 ¹³ Ω-cm or more, as described above, (a) the free edge 22a of the charging member 22 acts to prevent the development. Agent (toner particles) 14
Problems or drawbacks tend to occur, such as: it becomes relatively difficult to achieve sufficient triboelectric charging; and (b) undesirable edge effects occur in the image developed in the development zone 16. However, according to experiments conducted by the present inventors and their analysis, the thickness of the layer of the developer 14 held on the surface of the developer holding member 4 is determined by setting the so-called spike length using the free edge 22a of the charging member 22. Depending on the action, 10 to 50 μ, especially 25 to 35
If it is made sufficiently thin with μ, the above (a)
It has been found that the problems and defects described in (b) and (b) can be reliably avoided.

In order to make the thickness of the layer of developer 14 held on the surface of the developer holding member 4 extremely thin as described above, the charging member 22 is arranged as shown by the solid line in FIG. At least the tip of the developer holding member 4 is aligned with respect to the normal line of the surface of the developer holding member 4 (more specifically, the normal line of the surface of the developer holding member 4 at the position where the free edge 22a of the charging member 22 comes into pressure contact with the developer holding member 4). It is important that it is arranged so that it extends downstream at an angle α of 0 degrees to 90 degrees, preferably 10 degrees to 60 degrees, as viewed in the direction of movement shown by arrow 8 on the surface of 4. In addition, the free edge 22a of the charging member 22
It is important to contact the surface of the developer holding member 4 with a pressing force of 80 to 500 g/cm, particularly 100 to 300 g/cm. In order to sufficiently enhance the so-called panicle length setting effect of the free edge 22a of the charging member 22, the free edge 22a is preferably formed in the shape of a sharp knife edge, as clearly shown in FIG.

Next, the structure of the upstream edge 26 of the opening 12 of the developer container 6 located on the upstream side when viewed from the moving direction indicated by the arrow 8 on the surface of the developer holding member 4 will be explained. Similar to that of the electrostatic latent image developing device disclosed in the specification and drawings of the above issue, the upstream edge 26 is the uppermost portion of the travel path of the surface of the developer retaining member 4, in the illustrated embodiment designated by the number 28. It is preferable that the portion is positioned closer to or in contact with the surface of the developer holding member 4 on the downstream side as viewed in the moving direction of the surface of the developer holding member 4 than the portion indicated by . Such an upstream edge 26 may be defined by the free end of any suitable member that defines the upstream portion of the opening 12 of the developer container 6;
As clearly shown in the figure, an angle β of 0 degrees < β < 90 degrees, particularly 10 degrees < β < 50 degrees, with respect to a horizontal line passing through the uppermost part 28 of the movement path of the surface of the developer holding member 4. A piece 30 that extends downwardly and at an angle downstream when viewed in the direction of movement of the surface of the developer holding member 4.
Advantageously, said upstream edge 26 is defined by the free end of.

When the upstream edge 26 of the opening 12 of the developer container 6 is configured as described above, the developer 1 is removed from the surface of the developer holding member 4 on the upstream side of the upstream edge 26.
Even if the developer holding member 4 is peeled off, the peeled developer 14 is pushed downward due to its weight, and therefore the developer retaining member 4
It moves toward the developer container 6 downstream along the surface of the developer container 6 in the direction of movement indicated by the arrow 8, and is collected into the developer container 6. Therefore, the developer 14 peeled off from the surface of the developer holding member 4 on the upstream side of the upstream edge 26 does not float around and scatter.
A piece 3 whose upstream edge 26 extends obliquely as described above.
0, the developer 14 peeled off from the surface of the developer holding member 4 on the upstream side of the upstream edge 26 is guided by the lower surface of the piece 30. The developer holding member 4 moves along with the surface of the developer holding member 4 moving in the direction shown by the arrow 8, and is more reliably collected into the developer container 6. Furthermore, upstream edge 2
6 is extremely close to or in contact with the surface of the developer holding member 4, the developer holding member 4
Due to the presence of the developer 14 moving with the surface of the developer retaining member 4, the surface of the developer retaining member 4 becomes elastically somewhat concave or the piece 30 is elastically deflected, thereby causing the developer 14 to develop. It enters into the agent container 6.

a piece 30 whose free end defines the upstream edge 26;
can be formed integrally with the main body 24 of the developer container 6, or can be formed integrally with the main body 24 as in the illustrated example.
4 and one end (i.e., the upper end) of the body 24 is connected to the main body 24; however, it can be formed from a relatively conductive material having a resistivity lower than that of the developer material 14 and directly connected to the main body 24. Preferably, it is grounded either directly or via a suitable bias voltage source (not shown). In this way, due to charge transfer from the surface of the electrostatic latent image forming member 18 or frictional charging due to friction with the surface of the electrostatic latent image forming member 18, the developer holding member 4 is removed after development in the developing area 16. Even if an undesirable phenomenon occurs in which the developer 14 remaining on the surface of the developer holding member 4 or the surface of the developer holding member 4 itself becomes abnormally charged, the abnormally charged charge can be leaked to the ground through the piece 30.

Next, a description will be given of the peeling member 32, which may have substantially the same configuration as the peeling member used in the electrostatic latent image developing device disclosed in the specification and drawings of Japanese Patent Application No. 55-29629. The peeling member 32 is
As clearly shown in FIG. It is preferable that the brush is composed of a so-called brush having a large number of thin wires that are brought into contact with the surface of the agent holding member 4. Alternatively, the peeling member 32 may be suitably constructed from a blade piece whose free end is brought into contact with the surface of the developer holding member 4 at a desired position within the opening 12.

When the peeling member 32 as described above is provided, the developer retaining member 4 is not attached to the surface of the electrostatic latent image forming member 18 during development in the development area 16 and is removed from the developer holding member 4 after development. Developer 14 remaining on the surface
is reliably peeled off from the surface of the developer holding member 4 in the developer container 6 by the peeling action of the peeling member 32, and is mixed with other developer 14 in the developer container 6. Therefore, during the next development, the developer 14 in the developer container 6 is completely newly transferred to the downstream side of the peeling member 32 when viewed in the moving direction of the surface of the developer holding member 4 shown by the arrow 8. Agent holding member 4
The newly retained developer 14 is frictionally charged by the action of the charging member 22 and transported to the developing area 16. In this way, each time development is performed, the developer 14 is completely newly held on the surface of the developer holding member 4, charged, and transported to the development area 16. As the developer 14 remaining on the surface of the developer holding member 4 continues to remain on the surface of the developer holding member 4 without being peeled off, as development is repeatedly performed, the development becomes uneven and the developed image ( This makes it possible to prevent the undesirable phenomenon that development spots are formed on toner images.

Note that the area is not inside the developer container 6, but is located downstream of the development area 16 and upstream of the upstream edge 26 of the opening 12 of the developer container 6 when viewed in the moving direction of the surface of the developer holding member 4 shown by the arrow 8. It is also possible to arrange the peeling member 32 at the position, but in this case, the peeling member 32
This causes a problem in that the developer 14 peeled off from the surface of the developer holding member 4 is scattered around. Therefore, the stripping member 32 is arranged in the developer container 6 and configured to act on the surface of the developer retaining member 4 in the area within the opening 12, thereby making it possible for the stripping member 32 to It is preferable that the developer 14 peeled off from the surface of the developer holding member 4 by the action is reliably held within the developer container 6 without scattering to the surroundings.

The brush or blade piece that may be conveniently used as the stripping member 32 may be formed from any suitable material, preferably elastic, but relatively electrically conductive, having a resistivity less than that of the developer material 14. Preferably, it is formed from a material and connected to ground, either directly or via a suitable bias voltage source (not shown). In this way, the developer container 6
For reasons such as those already mentioned in connection with said piece 30 defining the upstream edge 26 of the opening 12,
After development in the development area 16, the developer holding member 4
Even if abnormal charging occurs on the developer 14 remaining on the surface of the developer holding member 4 or on the surface itself of the developer holding member 4, the abnormally charged charge can be leaked to the ground through the peeling member 32. In order to easily and sufficiently leak abnormally charged charges to the ground, it is desirable that both the piece 30 and the peeling member 32 be made of a relatively conductive material and grounded, rather than just one of them. .

Thus, the free end of the stripping member 32, which can be composed of a brush or a blade piece, extends over the entire width in the axial direction (i.e., the direction perpendicular to the plane of the paper in FIG. 1) with respect to the surface of the developer holding member 4. In order to achieve uniform contact and uniform action, it is necessary to manufacture and position the stripping member 32 with great precision with the surface of the developer holding member 4, but in practice it is difficult to do so. Although it is not impossible, it is extremely difficult, and even if it were possible to do so, as development is repeated, the peeling member 3 may be attached to the surface of the developer holding member 4.
2 will become uneven. In view of this, for example, the developer holding member 4 as shown in the specific example shown in FIG.
When the roller 10 is composed of a roller 10, it is preferable that the roller 10 is rotated in the direction of the arrow 8 and reciprocated over a predetermined range in the direction of its central axis of rotation. In this way, the action of the peeling member 32 on the surface of the developer holding member 4 can be averaged and made sufficiently uniform. Instead of reciprocating the developer holding member 4 in the axial direction, the peeling member 32 can also be reciprocated in the axial direction, but if the developer holding member 4 is reciprocated in the axial direction, the developing area Since the developing action at 16 can also be averaged in the axial direction and extremely uniform development can be achieved, the developer holding member 4 can be moved along the axial direction by an appropriate driving means (not shown) without causing any particular problems. As long as the developer holding member 4 can be reciprocated in the direction
It is preferable to reciprocate in the axial direction.
Of course, if desired, both the developer retaining member 4 and the stripping member 32 can be reciprocated in the axial direction separately so as not to be synchronized with each other.

[Brief explanation of the drawing]

FIG. 1 is a simplified sectional view showing a specific example of an electrostatic latent image developing device constructed according to the present invention. 2... Electrostatic latent image developing device, 4... Developer holding member, 6... Developer container, 12... Opening of developer container, 14... Developer, 22... Charging member.

Claims (1)

[Claims for Utility Model Registration] 1. A developer retaining member having a surface that can be moved through an endless movement path and containing a one-component developer consisting only of toner particles capable of retaining an electric charge, a developer container for supplying the developer to the surface of the developer holding member through an opening formed in a portion facing a part of the movement path, the developer holding member in the opening of the developer container; A charging member is disposed on the downstream edge of the surface of the member when viewed in the direction of movement, the charging member being at least partially made of an elastic material and having a free edge brought into pressure contact with the surface of the developer holding member. In an electrostatic latent image developing device; the surface layer of the developer retaining member having a thickness of at least 100 μm is determined by the measurement method according to JIS standard K-2808.
The charging member has a hardness of 15 degrees to 60 degrees, and at least the leading end of the charging member has a hardness of 0 to 0 on the downstream side when viewed from the direction of movement of the surface of the developer holding member with respect to the normal to the surface of the developer holding member. degrees to 90
and the free edge of the charging member is pressed against the surface of the developer holding member with a pressing force of 80 to 500 g/cm, thus An electrostatic latent image developing device characterized in that the layer thickness of the developer retained on the surface is limited to 10 to 50μ by the action of the free edge of the charging member. 2. The electrostatic latent image developing device according to claim 1, wherein the angle α is from 10 degrees to 60 degrees. 3. The electrostatic latent image developing device according to claim 1 or 2, wherein the free edge of the charging member is shaped like a sharp knife. 4. The electrostatic latent image developing device according to any one of claims 1 to 3, wherein the pressing force is 100 to 300 g/cm. 5. The electrostatic latent image developing device according to any one of claims 1 to 4, wherein the layer thickness of the developer is 25 to 35 μm. 6. The surface layer of the developer retaining member having a thickness of at least 100 μm is made of an electrostatic latent material according to any one of claims 1 to 5 of the utility model registration claim having a specific resistance of 10 ¹³ Ω-cm or more. Image developing device.