JPH0246950B2 - - Google Patents

Description

Detailed Description of the Invention <Technical Field> The present invention relates to 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. relates to an electrostatic latent image developing device of the type that uses a one-component developer consisting only of toner particles capable of retaining an electric charge.

<Prior art and its problems> Electrostatic latent image developing devices used in electrostatic copying machines and the like to apply toner to an electrostatic latent image to make it a visible image can be roughly divided into carrier particles and toner particles. There are two types of devices: those that use a so-called two-component developer, and those that use a one-component developer that consists only of toner particles. In order to stably perform good development, the ratio of carrier particles to toner particles must always be maintained at the required value, and therefore, depending on the consumption of toner particles due to the performance of development, There are difficult problems to solve, such as the need to properly replenish toner particles. Therefore, in recent years, there has been a tendency to advantageously use electrostatic latent image developing devices that use a one-component developer.

Therefore, depending on the characteristics of the one-component developer used, an electrostatic latent image developing device that uses a one-component developer is capable of developing (a) a one-component developer consisting only of relatively conductive toner particles; (b) devices that use a one-component developer consisting only of relatively insulating toner particles;

Apparatuses and methods using the above developer (a) are disclosed, for example, in Japanese Patent Publication No. 37-491, Japanese Patent Publication No. 37-492, Japanese Patent Publication No. 39-20695, Japanese Patent Application Laid-Open No. 49-5035, It is disclosed in known documents such as the specification and drawings of Patent No. 2976144, the specification and drawings of US Pat. No. 3,909,258, and the specification and drawings of US Patent No. 4,081,571. As is clear from such known documents, when using the developer described in (a) above, the developer is held on the surface of the developer holding member and transported to the development area to form an electrostatic latent image. Only contact is required to cause the developer to adhere to the electrostatic latent image as desired; therefore, no special treatment, such as charging the developer, is required prior to contacting the electrostatic latent image. The advantage is that it doesn't. However, since the toner particles constituting the developer are relatively conductive, it is relatively difficult to successfully transfer a toner image to a transfer member in, for example, a toner image transfer type electrostatic copying machine. There's a problem.

On the other hand, apparatuses and methods using the above developer (b) are disclosed, for example, in JP-A-51-26046 and JP-A-52-26046.
Publication No. 106734, Japanese Patent Application Laid-Open No. 1983-3233, Japanese Patent Application Publication No. 1983
It is disclosed in known documents such as JP-A-110843, JP-A-53-111737, JP-A-53-135335, JP-A-53-23638, and JP-A-54-136339. As is clear from such known documents, the apparatus using the developer of (b) above comprises a developer retaining surface, which is in the form of a roll or an endless belt, and has a surface that is moved through an endless travel path. The developer container includes a member, a developer container having an opening formed in a portion facing a portion of the movement path, and means for charging the developer by an appropriate method such as triboelectric charging. The charging means is constituted by a charging member disposed at the downstream edge of the opening of the developer container (that is, one edge located on the downstream side as viewed in the moving direction of the surface of the developer holding member). It's convenient. At least a portion of this charging member is made of an elastic material, and its free end is brought into pressure contact with the surface of the developer holding member. In the above-mentioned device, the developer contained in the developer container is held on the surface of the developer holding member and charged, and then transferred to the developing area by movement of the surface of the developer holding member. The developer material is carried and applied to the electrostatic latent image, thus causing the desired deposition of the developer onto the electrostatic latent image to achieve development.

When using the developer described in (b) above, the toner particles constituting the developer are relatively insulating, so the above-mentioned problem occurs when using the developer described in (a) above. There are no shortcomings. However, (b) above
The conventional electrostatic latent image developing device using the developer has the following drawbacks or problems to be solved.

That is, in a conventional electrostatic latent image developing device using the developer described in (b) above, as will be described in more detail later, the upstream edge of the opening of the developer container (i.e., the movement of the surface of the developer holding member) There is a tendency for the developer to scatter from near one edge (located on the upstream side) and contaminate other components such as an electrostatic copying machine in which the electrostatic latent image developing device is used.

The toner particles constituting the developer in (b) above are:
As can be easily understood from the above-mentioned known documents, in general, the developer is often non-magnetic and cannot be magnetically attracted, but if the developer is composed of non-magnetic toner particles, Therefore, the developer cannot be magnetically attracted to and held on the surface of the developer holding member by the action of the generated magnetic field, and therefore mechanically (for example, the surface of the developer holding member and the developer (mechanical mutual engagement or adhesion with)
It is necessary to hold the developer on the surface of the developer holding member and/or electrically (for example, adsorption by Wanderwaalska). However, as is well known to those skilled in the art, compared to the holding force when a developer made of magnetic toner particles is magnetically held by the action of a magnetic field, the holding force of a developer made of non-magnetic toner particles is The holding force when holding the agent mechanically and/or electrically is generally weak. Therefore, when using a developer composed of non-magnetic toner particles, the developer is relatively easily dispersed from the surface of the developer holding member, and the above-mentioned problem of developer scattering is especially a problem. Easy to occur.

<Object of the Invention> The present invention has been made in view of the above-mentioned facts, and its first object is to provide an electrostatic latent image developing device that uses the developer described in (b) above. Even if the toner particles constituting the agent are non-magnetic and therefore the developer is held on the surface of the developer holding member mechanically and/or electrically rather than magnetically, It is an object of the present invention to provide a new and excellent electrostatic latent image developing device in which scattering of developer is sufficiently prevented.

<Solution Means of the Invention> The solution means of the present invention to achieve the above-mentioned object is such that the upstream edge of the opening of the developer container is set at a distance of 10 mm from the horizontal line passing through the uppermost part of the movement path of the surface of the developer holding member. defined by the free end of the piece extending downwardly and downstream viewed in the direction of travel of the surface of the developer retaining member at an angle α, with degrees ≤ α ≤ 50 degrees; It is positioned downstream of the uppermost portion of the surface movement path so as to be close to or in contact with the surface of the developer holding member.

That is, the present invention includes a developer holding member having a surface that can be moved through an endless movement path, and a developer container having an opening formed in a portion facing a part of the movement path. , a downstream edge of the opening of the developer container located on the downstream side as viewed in the direction of movement of the surface of the developer holding member is formed at least partially of an elastic material, and a free end thereof The developer holding member is defined by a charging member that is brought into pressure contact with the surface of the holding member, and is a one-component developer consisting only of toner particles that can hold the charge contained in the developer container. In an electrostatic latent image developing device of the type in which developer is held on the surface of a member and is charged and carried to a development area by movement of the surface of the developer holding member to be applied to an electrostatic latent image to be developed; The upstream edge of the opening of the developer container located on the upstream side when viewed in the moving direction of the surface of the developer holding member is aligned with a horizontal line passing through the uppermost part of the movement path on the surface of the developer holding member. defined by the free end of the piece extending downwardly and downstream at an angle α of 10 degrees≦α≦50 degrees with respect to the surface of the developer retaining member, and Positioned so as to be close to or in contact with the surface of the developer holding member, downstream of the uppermost part of the movement path of the surface of the developer holding member, as viewed in the moving direction of the surface of the developer holding member. An electrostatic latent image developing device is provided.

<Preferred Embodiments of the Invention> 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.

Outline of the overall structure Referring to FIGS. 1 and 2, the overall structure of the electrostatic latent image developing device, which is indicated by the number 2, is outlined. The electrostatic latent image developing device 2 includes a developer holding member. 4 and a developer container 6. Developer holding member 4
may be of any form, such as an endless belt well known to those skilled in the art, as long as its surface capable of retaining the developer is of such form that it can be moved through an endless path of travel; In the example shown in FIG. (transferred through a circular path of travel defined by a circumferential surface).
The developer container 6 has an opening formed in a portion of the surface of the developer holding member 4 facing a part of the movement path, that is, in the illustrated example, a part facing a part of the circumferential surface of the roller 10. It has 12.

In such an electrostatic latent image developing device 2, the developer 14 contained in the developer container 6 comes into contact with the surface of the developer holding member 4 through the opening 12 and is held there, and is also later Charged as detailed. The developer 14 held on the surface of the developer holding member 4 is moved by the movement of the surface of the developer holding member 4, so that the developer 14 is moved by the roller 1 in the illustrated example.
0 in the direction shown by arrow 8, development area 1
6. 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 charged developer (toner particles) held on the surface of the developer holding member 4 adheres to the surface of the electrostatic latent image forming member according to the potential or charge of the electrostatic latent image. The electrostatic latent image is developed into a visible image (toner image).

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

Developer In the electrostatic latent image developing device 2 according to the present invention,
It is important to use, as the developer 14, a one-component developer consisting only of toner particles that can be charged, in other words, can retain an electric charge, by a method as mentioned below. The toner particles themselves capable of retaining an electric charge are known as relatively insulating toner particles, and in the electrostatic latent image developing device 2 according to the present invention, the toner particles themselves are 10 ¹²
A one-component developer consisting only of toner particles having a specific resistance of Ω·cm or more, particularly 10 ¹⁴ Ω·cm or more, is preferably used. Further, it is desirable that the toner particles constituting the one-component developer have a small particle size and a large specific surface area so that they can be easily and quickly charged to the saturation charge amount.
Those having an average particle size of 5 μ to 30 μ, particularly 20 μ or less, especially 15 μ or less are preferred.

Developer Holding Member In the electrostatic latent image developing device 2 according to the present invention,
A one-component developer 14 consisting only of relatively insulating toner particles as described above is used, and before such developer 14 retained on the surface of the developer retaining member 4 is conveyed to the development zone 16. As mentioned later, the developer 1 is
4 is charged. Therefore, in order to charge the developer 14 sufficiently and easily, and also to reliably prevent overcharging of the developer 14,
As is well known to those skilled in the art, it is desirable that the resistivity of at least the surface of the developer holding member 4 be smaller than the resistivity of the developer 14. On the other hand, according to the fact that the present inventors have confirmed through experiments, the resistivity of the surface of the developer holding member 4 is excessively reduced to 10 ³ Ω・
It has been found that if it is made smaller than cm, the sharpness of the developed image (toner image) decreases and so-called fog tends to occur. Therefore, at least the surface of the developer holding member 4 preferably has a resistivity of 10 ³ Ω·cm or more, which is smaller than the resistivity of the developer 14 described above.

On the other hand, as is well known to those skilled in the art, the relatively insulating developer 14 composed only of toner particles as described above is generally non-magnetic and is not magnetically attracted. When the developer 14 is magnetic, a magnet is disposed within the developer holding member 4, and the surface of the developer holding member 4 is affected by the action of the magnetic field generated by the magnet. The developer 14 can be conveniently attracted and held magnetically. However, when the developer 14 is non-magnetic, it is necessary to mechanically or electrically hold it on the surface of the developer holding member 4 instead of magnetically attracting and holding it. In order to mechanically and electrically hold the developer 14 sufficiently reliably on the surface of the developer holding member 4, the surface layer of the developer holding member 4 has a thickness of at least 100 μm.
It is preferable to use a material that is flexible and has excellent recovery properties. When the hardness of the surface layer of the developer holding member 4 is excessively high, the amount of the developer 14 held on the surface of the developer holding member 4 tends to decrease excessively, and the holding power of the developer 14 tends to become excessively weak. There is. On the other hand, when the hardness of the surface layer of the developer holding member 4 is excessively small and the restorability is poor, when the free end of the charging member for charging the developer 14 is pressed against the developer holding member 4, as will be mentioned later. In such cases, the surface of the developer holding member 4 is easily damaged by the pressure contact, or it is extremely difficult to control the thickness of the layer of the developer 14 held on the surface of the developer holding member 4. Failures such as this may occur.

By satisfying the above-mentioned requirements on the surface of the developer holding member 4, the developer can be easily and precisely formed into a desired form (for example, a roller form as shown in FIGS. 1 and 2, or an endless belt form). To manufacture the holding member 4, first, a metal support base of the required form is formed from a suitable metal member such as aluminum, and then a material satisfying the above-mentioned requirements is coated on the surface of the metal support base. It is preferable to bond the surface layers formed by, for example, an adhesive. As the surface layer, a material containing silicone rubber with a polymerization ratio of 10% or more is preferably used as a material that is flexible and has excellent restorability. Since silicone rubber is a material with a fairly large specific resistance value, in order to make the specific resistance of the surface layer reach the desired value as mentioned above, a required amount of a resistance control agent such as carbon powder or aluminum powder can be mixed in. .

In addition, the present inventors have confirmed through experiments that a high-resistance portion having a resistivity larger than that of the surface layer is formed on the surface of the above-mentioned surface layer in the form of 50 meshes to 800 meshes. It has been found that the sharpness of the developed image (toner image) can be improved by scattering the toner particles in a distributed manner. Such a high resistance part can be formed by applying silicone rubber or a mixture thereof mixed with an appropriate resistance control agent on the surface of the above-mentioned surface layer by a screen method which is known per se. Can be done. In this case, it is desirable that the thickness of the high resistance portions scattered on the surface of the above-mentioned surface layer be 500 μm or less. If the thickness of the high-resistance portion is greater than 500 μm, the thickness of the layer of developer 14 held on the surface of the developer holding member 4 may be made uniform due to the scattered high-resistance portions. becomes difficult.

The form of the developer holding member 4 itself may be any form as long as the surface capable of holding the developer 14 can be moved through an endless movement path, as described above.
From the viewpoint of miniaturization of the device and ease of manufacturing, it is preferable to use a roller-shaped device, especially a hollow roller 10 as shown in FIGS. 1 and 2, which is made hollow to reduce the weight. It is preferable that the When the developer holding member 4 is constituted by a roller 10, an electrostatic latent image forming member 18 is moved in the direction of an arrow 20 in the developing area 16, as shown in FIGS. 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 in which the surface of the developer holding member 4 moves. When the roller 10 is rotated in the opposite direction to the direction shown by the arrow 8, the development area 1 is
A so-called reservoir of the developer 14 is generated downstream of the developer 14, and after passing through the development zone 16, the surface of the electrostatic latent image forming member 18 tends to come into contact with the reservoir of the developer 14. After that, the developer 14 falls onto the surface of the electrostatic latent image forming member 18, and the developed image (toner image) tends to have a so-called background stain. Further, it is preferable to rotate the roller 10 at a rotational speed such that the surface of the roller 10 moves at a speed 1.5 to 5 times the speed of movement of the surface of the electrostatic latent image forming member 18. If the moving speed of the surface of the roller 10 is made smaller than 1.5 times the moving speed of the surface of the electrostatic latent image forming member 18, the sharpness of the developed image (toner image) will decrease and an insufficient development phenomenon will occur.
Conversely, if the speed of movement of the surface of the roller 10 is greater than five times the speed of movement of the surface of the electrostatic latent image forming member 18, the sharpness of the developed image (toner image) will decrease and background smear will occur. It has also been experimentally confirmed that scattering of the developer 14 occurs near the developing area 16.

Developer Container In the developer container 6 used in the electrostatic latent image developing device 2 according to the present invention, the developer holding member 4
Near the upstream edge of the opening 12 formed in a portion facing a part of the movement path on the surface of the developer holding member 4, located on the upstream side in the direction of movement of the surface of the developer holding member 4 (i.e., the direction indicated by the arrow 8). In order to prevent the developer 14 from scattering near the downstream edge located on the downstream side, it is important that the upstream edge and downstream edge of the opening 12 are configured as follows.

First, to explain the structure of the downstream edge of the opening 12, in the developer container 6 shown in FIGS. The charging member 22 is made of an elastic material, and its free end is defined by a charging member 22 that is brought into pressure contact with the surface of the developer holding member 4. This charging member 22 may be formed integrally with the main body 24 of the developer container 6;
It is convenient to form it separately from the main body 24, which can be formed from a suitable synthetic resin plate or metal plate, and to have one end (the right end in FIG. 1) fixed to the main body 24. The charging member 22 can be made of any elastic material, but as will be explained next, it has the important function of acting on the developer 14 held on the surface of the developer holding member 44 to charge it. From this point of view, 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 described above. A particularly suitable material for forming charging member 22 may include spring steel. Further, instead of spring steel, metal materials such as molybdenum, tungsten, or aluminum can also be suitably used. When the charging member 22 is formed from spring steel or a metal material such as molybdenum, tungsten, or aluminum, heat treatment or anodic oxidation treatment is performed to generate an oxide film on the surface to increase corrosion resistance, wear resistance, etc. Preferably. The charging member 22 can be formed from a relatively low-resistance synthetic resin material instead of the above-mentioned metal material, but in this case, a synthetic resin material with sufficient elasticity and sufficient mechanical strength should be selected. is important.

The above-described charging member 22 shown in FIGS. 1 and 2 has a surface of the developer holding member 4 indicated by the arrow
When moving in the direction indicated by , it contacts the surface of the developer holding member 4 at the opening 12 of the developer container 6 and acts on the developer 14 held therein, causing the developer 14 to be triboelectrically charged. . 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. In addition to triboelectrically charging the developer 14, the charging member 22 charges the developer 14 held on the surface of the developer holding member 4 and transported to the development area 16.
It also performs a so-called panicle length setting function to adjust the thickness of the layer to a desired value. The thickness of the layer of the developer 14 held on the surface of the developer holding member 4 and conveyed to the developing area 16, that is, the length of the ears, is determined to appropriately control the pressing force of the free end of the charging member 22 against the surface of the developer holding member 4. It is adjusted to the required value by adjusting.

In a conventional electrostatic latent image developing device of the type that holds the developer on the surface of the developer holding member 4 and triboelectrically charges the developer before conveying it to the development area, generally, as shown in FIG. As illustrated by the two-dot chain line,
The opening 12 of the developer container 6 is located upstream of the developing area 16 when viewed in the moving direction of the surface of the developer holding member 4.
A charging member 22' whose free end is brought into pressure contact with the surface of the developer holding member 4 at an appropriate position downstream of the downstream edge of the developer holding member 4 is often disposed separately from the developer container 6. Such a conventional electrostatic latent image developing device includes a developer 14 held on the surface of the developer holding member 4 at a location separate from the developer container 6, that is, at a location outside the developer container 6. Since the free end of the charging member 22' acts on the charging member 22', there is a problem in that the developer 14 is separated from the surface of the developer holding member 4 on the upstream side of the free end of the charging member 22' and is caused to float and scatter around. exist. In particular, when the developer 14 is non-magnetic and therefore is held on the surface of the developer holding member 4 not magnetically but mechanically or electrically, the developing agent on the surface of the developer holding member 4 is The adhesive force of the developer 14 is relatively weak, and the developer 14
Since the developer is relatively easily peeled off and floated from the surface of the developer holding member 4, the above-mentioned scattering of the developer becomes a big problem.

On the other hand, in the illustrated electrostatic latent image developing device 2 constructed according to the present invention, the charging member 22
defines the downstream edge of the opening 12 of the developer container 6 and is configured to perform both charging and frictional functions. In such a case, as can be easily understood from FIG. 1, the upstream side of the free end of the charging member 22 is located within the developer container 6, and therefore, the upstream side of the free end of the charging member 22 is The peeling of the developer 14 from the surface of the developer holding member 4 occurs within the developer container 6, and therefore the developer peeled off from the surface of the developer holding member 4 by the action of the free end of the charging member 22. The agent 14 is reliably contained within the developer container 6 and does not float or scatter outside the developer container 6.

Next, to explain the configuration of the upstream edge of the opening 12, in many conventional electrostatic latent image developing devices, the opening 12 of the developer container 6 moves in the direction of movement of the surface of the developer holding member 4 (i.e., the arrow 8 The upstream edge 26' located on the upstream side as seen in the direction indicated by is the uppermost part of the movement path of the surface of the developer holding member 4, as illustrated by the two-dot chain line in FIG. is located upstream of the portion indicated by number 28 in the moving direction of the surface of the developer holding member 4, that is, in a region where the movement path of the surface of the developer holding member 4 rises toward the downstream. There is. Therefore, there is a problem that the developer 14 is scattered near the upstream edge of the opening 12 of the developer container 6. To explain this point in more detail, it is necessary that the upstream edge 26' located at the position shown by the two-dot chain line in FIG. 1 be extremely close to or in contact with the surface of the developer holding member 4. Otherwise, as will be readily understood, the developer 14 in the developer container 6
Due to its own importance, the developer falls downward through the gap between the upstream edge 26' and the surface of the developer holding member 4 and is scattered around. On the other hand, if the upstream edge 26' is brought into close proximity to or in contact with the surface of the developer holding member 4, the upstream edge 26' will not be attached to the surface of the electrostatic latent image forming member 18 during development in the development area 16. The upstream side of the upstream edge 26' interferes with the developer 14 remaining on the surface of the developer holding member 4 and moving together with the surface of the developer holding member 4,
Thereby, the developer 14 tends to be peeled off from the surface of the developer holding member 4. The developer 14 peeled off from the surface of the developer holding member 4 on the upstream side of the upstream edge 26' falls downward and floats and scatters. Such an undesirable phenomenon is particularly caused by the fact that the developer 14 is non-magnetic, and therefore the developer 14 cannot be held firmly enough magnetically on the surface of the developer holding member 4, and mechanically. This phenomenon occurs noticeably when electrical maintenance is required.

Electrostatic latent image developing device 2 configured according to the present invention
In order to reliably prevent the developer 14 from scattering near the upstream edge of the opening 12 of the developer container 6, as clearly shown in FIG.
The upstream edge 26 of the opening 12 located on the upstream side when viewed in the moving direction of the surface of the developer holding member 4 (that is, the direction shown by the arrow 8) is the uppermost part of the movement path of the surface of the developer holding member 4. , in the specific example shown, is downstream from the part indicated by number 28 in the moving direction of the surface of the developer holding member 4, and therefore the moving path of the surface of the developer holding member 4 descends toward the downstream. It is important that the developer holding member 4 is positioned in close proximity to or in contact with the surface of the developer holding member 4 in this area.

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 4 is peeled off, the peeled developer 14 moves in the direction shown by the arrow 8 without scattering to the surroundings due to the guiding and restraining action of the lower surface of the piece 30 extending in an inclined manner as described above. Developer holding member 4
The developer smoothly moves downstream along with the surface of the developer, and is collected into the developer container 6. . When the upstream edge 26 is brought into close proximity to or in contact with the surface of the developer holding member 4, the presence of the developer 14 moving together with the surface of the developer holding member 4 causes the surface of the developer holding member 4 to is elastically somewhat concave or the piece 30 is elastically deflected, thereby causing the developer material 14 to
enters into the developer container 6. If the inclination angle α of the piece 30 that defines the upstream edge 26 becomes too large, a large opening will occur in the upstream direction between the surface of the developer holding member 4 and the lower surface of the piece 30 on the upstream side of the upstream edge 26. An angularly open space is created, therefore, a piece 30 for the developer peeled off from the surface of the developer retaining member 4 on the upstream side of the upstream edge 26.
The restraining effect of the developer 14 becomes weak, and the effect of preventing the developer 14 from floating and scattering becomes insufficient. Conversely, if the inclination angle α of the piece 30 defining the upstream edge 26 becomes too small, as will be easily understood, not only the free end edge of the piece 30, i.e. the upstream edge 26 but also the base of the piece 30 The end edge is also located close to the surface of the developer holding member 4, and therefore the developer 14 is peeled off from the surface of the developer holding member 4 even on the upstream side of the proximal edge of the piece 30 itself. There is a tendency for the developer 14 to float and scatter around.

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 development 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 is abnormally charged, the abnormally charged charge can be leaked to the ground through the piece 30.

Peeling Member In the illustrated electrostatic latent image developing device 2 constructed according to the present invention, in addition to the above-mentioned components,
Further, the surface of the developer holding member 4 is rubbed in the area inside the opening 12 of the developer container 6 to remove the developer holding member 4.
A peeling member 32 is provided for peeling off the developer 14 adhered to or held on the surface.

The stripping member 32 is disposed within the developer container 6, as clearly shown in FIGS. 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 developer holding member 4 at the middle part of the opening 12 in the direction. 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 development, the developer 14 in the developer container 6 is completely newly added to the developer on 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. 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 ( It is possible to prevent undesirable development in which development spots are formed on a toner image.

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 important to ensure that the developer 14 peeled off from the surface of the developer holding member 4 by the action is held within the developer container 6 without being scattered around.

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 possible to make both the piece 30 and the peeling member 32 from a relatively conductive material and ground them, rather than just one of them. desirable.

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 be averaged in the axial direction and extremely uniform development can be achieved, the developer holding member 4 can be moved along the axis 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.

Specific example configured to easily change charging polarity of developer In the electrostatic latent image developing device 2 shown in FIGS. As a result, it becomes triboelectrically charged. As is well known, the charging polarity of the developer 14 at this time is as follows:
It is uniquely defined by the relative relationship between the material of the developer 14 and the material of the charging member 22 in the triboelectrification series. Therefore, in order to change the charging polarity of the developer 14, it is necessary to change the material of the charging member 22, and it is not impossible to change the charging polarity of the developer 14 appropriately in an actual device. However, it is extremely difficult.

On the other hand, after the developer 14 is charged, the development area 1
In the electrostatic latent image developing device of the type 6, if the charging polarity of the developer 14 can be changed appropriately, the electrostatic latent image can be developed into a positive image or a negative image as required. It is possible. For example, when the electrostatic latent image formed on the electrostatic latent image forming member 18 has a positive potential or charge in the image area, the developer 14 carried to the development area 16
If charged with a negative charge, the electrostatic latent image will be developed into a positive image, and conversely, if charged with a positive charge, the electrostatic latent image will be developed into a negative image.

The electrostatic latent image developing device 102 illustrated in FIG.
Electrostatic latent image developing device 2 illustrated in FIGS. 1 and 2
By making the following modifications to the above, the charge polarity of the developer 114 can be changed extremely easily as required.

In the electrostatic latent image developing device 102 shown in FIG. 3, the developer 114 is not triboelectrically charged by the mechanical action of the charging member 122 on the developer 114, but is electrically charged as described below. The charging member 122 and the developer holding member 1 are
04, and thereby the developer 114 held on the surface of the developer holding member 104 is charged. Therefore, the free end of the charging member 122 is not necessarily connected to the developer holding member 1.
It does not need to be in pressure contact with the surface of 04,
It is only necessary that the charging member 122 be brought into electrical contact with the developer 114 held on the surface of the developer holding member 104 on the upstream side of the developing area 116, and the charging member 122 may be provided separately from the developer container 106. It can also be placed. However, the first
As in the case of the specific example illustrated in FIGS.
The charging member 122 is connected to the opening 112 of the developer container 106.
The free end of the charging member 122 is elastically pressed against the surface of the developer holding member 104 which is moved in the direction shown by the arrow 108, thereby allowing the development to be carried out. Developer 114 held on the surface of the agent holding member 104
The charging member 122 also performs a so-called spike length setting function that defines the thickness of the layer, and also reliably prevents the developer 114 from scattering near the upstream edge of the opening 112 of the developer container 106. Eggplant is preferred.

The electrical means for applying the charging DC voltage between the charging member 122 and the developer holding member 104 includes a changeover switch mechanism 140 . The illustrated changeover switch mechanism 140 includes two contacts 142a and 14 electrically connected to the charging member 122.
2b, two contacts 144a and 144b electrically connected to the developer holding member 104, and two input terminals 146 and 148. Two input terminals 146 and 148 are connected to member 150 as shown in the drawing.
is fixed to the member 150, and is integrally formed with the member 150 to select either a first operating position indicated by a two-dot chain line 150' or a second operating position indicated by a two-dot chain line 150'' in FIG. The member 150 is positioned at the first working position 1.
50', input terminal 146 is connected to contact 142a and thus to charging member 122, and input terminal 148 is connected to contact 144a and thus to developer retaining member 104. When the member 150 is positioned in the second operative position 150'', the input terminal 146 is connected to the contact 144b and thus to the developer retaining member 104, and the input terminal 148 is connected to the contact 142b and thus to the charging member 122. A power supply circuit having a direct current 152 can be connected between the two input terminals 146 and 148 as shown in FIG. 4-A.

In the electrostatic latent image developing device 102 equipped with the electrical means as described above, the changeover switch mechanism 140
member 150 from the first working position 150' to the second working position 150'.
When switched to the operating position 150'', the charging member 12
The polarity of the charging DC voltage applied between the developer holding member 104 and the developer holding member 104 is reversed, so that the developer 1 held on the surface of the developer holding member 104
The charging polarity of 14 can be changed. Therefore, by simply operating the changeover switch mechanism 140, the arrow 1
The electrostatic latent image on the electrostatic latent image forming member 118, which is moved in the direction indicated by 20, can be selectively developed into either a positive image or a negative image as required.

On the other hand, in an electrostatic latent image developing device of the type that carries the charged developer 114 on the surface of the developer holding member 104 to the development area 116 and applies it to the electrostatic latent image, the developer holding member 104 is transferred during development. If a so-called developing bias DC voltage is applied between the electrostatic latent image forming member 118 and the electrostatic latent image forming member 118 on which the electrostatic latent image to be developed is formed,
It is known that it is possible to effectively prevent the developer 114 from adhering to the non-image area of an electrostatic latent image, and to develop an excellent image (toner image) without background smear. In addition to the above-described charging DC voltage, the developer holding member 104 and the electrostatic latent image forming member 1
In order to also apply the above-mentioned developing bias voltage between
Between the two input terminals 146 and 148 of 40, instead of the power supply circuit shown in FIG. 4-A, two DC power supplies 15 connected in series are connected as shown in FIG. 4-B.
4 and 156, and the electrostatic latent image forming member 118 is connected to the power supply circuit 2 of the power supply circuit.
It is only necessary to electrically connect between the two DC power supplies 154 and 156. In this way, the changeover switch mechanism 14
When the 0 member 150 is in the first working position 150', a charging DC voltage is applied between the charging member 122 and the developer holding member 140 by both DC power sources 154 and 156. At the same time, a developing bias DC voltage is applied between the developer holding member 104 and the electrostatic latent image forming member 118 by the DC power supply 156. and,
When the member 150 of the changeover switch mechanism 140 is switched from the first operating position 150' to the second operating position 150'', the polarities of both the charging DC voltage and the developing bias DC voltage are simultaneously reversed, and the charging A charging DC voltage is applied between the member 122 and the developer holding member 104 by both DC power sources 156 and 154, and a charging DC voltage is applied between the developer holding member 104 and the electrostatic latent image forming member 118. During this time, a developing bias DC voltage is applied by the DC power supply 154.

The power supply circuits shown in Figures 4-A and 4-B include a DC power supply, but instead of these power supply circuits, an AC power supply 158 and a forward rectifier 1 are used.
60 and a reverse rectifying element 162 as shown in FIG. 4C may also be used. When using the power supply circuit shown in FIG. 4-C, one of the two input terminals 146 and 148 of the changeover switch mechanism 140 is connected to
0 and the other 148 are connected in parallel to one end of an AC power source 158 via a reverse rectifying element 162, and the electrostatic latent image forming member 118 is electrically connected to the other end of the AC power source 158. Ru. It goes without saying that even when the power supply circuit shown in Figure 4-C is used in this way, substantially the same effect can be obtained as when the power supply circuit shown in Figure 4-B is used. It can be easily understood.

In addition, when using the power supply circuit shown in FIG. 4-C, the forward rectifier 160 and the reverse rectifier 1
There is a pulsating current (ripple) component in the DC voltage obtained through the DC voltage 62, but if undesirable development occurs due to the presence of the pulsating current component in the charging DC voltage and the developing bias DC voltage, A pulsating current eliminating element (not shown) such as a capacitor or a coil may be interposed.

In an electrostatic copying machine or the like in which the electrostatic latent image developing device 102 is used, as is well known to those skilled in the art, a charging corona discharger used for forming an electrostatic latent image and a charging corona discharger used for transferring the electrostatic latent image are used. Various types of corona dischargers are often used, such as a transfer corona discharger used to remove residual charges, and a static elimination corona discharger used to remove residual charges. In such a case, a part of the discharge current of the corona discharger can be converted to an appropriate current without using the DC or AC power supply used in the power supply circuits shown in Figures 4-A to 4-C. It can be collected by a collection member and conveniently used as a power source for the charging DC voltage and the developing bias DC voltage.

FIG. 4-D shows that a part of the discharge current of the AC corona discharger 164 is collected by a current collecting member 166 and used as a power source for the charging DC voltage and the developing bias DC voltage. An example of a circuit configuration for the case is shown below. As shown in FIG. 4-D, the current collecting member 166 is connected to the AC corona discharger 1.
It is disposed facing an opening formed in the upper surface of the shield case 168 of the AC corona discharger 164, and collects a part of the discharge current from the discharge electrode 170 of the AC corona discharger 164, which originally flows from the shield case 168 to the ground. . The current collecting member 166 itself may have an appropriate shape such as a plate-shaped body or a thin wire, and may be formed from an appropriate material capable of collecting the discharge current. It is preferable to use a material that has been subjected to an ozone-resistant treatment such as the formation of a metal oxide film so that it will not be adversely affected by the ozone present. For example, the current collecting member 166 can be suitably formed from a metal material such as tungsten, molybdenum, or aluminum on which a metal oxide film is formed by anodizing or the like. The current collecting member 166 has a forward rectifying element 172 similar to the AC power source 158 in FIG. 4-C.
is connected to one of the two input terminals 146 and 148 of the changeover switch mechanism 140 shown in FIG. is connected to the other input terminal 148 of input terminals 146 and 148 of. On the other hand, the electrostatic latent image forming member 118 (FIG. 3)
is grounded and electrically connected indirectly to the current collection member 166.

When the electrostatic latent image developing device 102 shown in FIG. 3 is used with the above-described circuit configuration shown in FIG. 4-D, a special power source is used for the charging DC voltage and the developing bias DC voltage. Needless to say, it is obvious that the same effects as those obtained when using the power supply circuit shown in FIG. 4-C can be obtained without the need to do so.

FIG. 4-E shows that a part of the discharge current of the positive DC corona discharger 178 is collected by the current collection member 180, and a part of the discharge current of the negative DC corona discharger 182 is collected by the current collection member 180. An example of a circuit configuration is shown in which the particles are collected by the collecting member 184 and used as a power source for the charging DC voltage and the developing bias DC voltage. In the circuit configuration of FIG. 4-E, the current collection member 180 connects the two input terminals 14 of the changeover switch mechanism 140 shown in FIG.
6 and 148, and the current collecting member 184 is connected to one of the selector switch mechanisms 146 and 148 shown in FIG.
The other 14 of the two input terminals 146 and 148 of 0
Connected to 8. On the other hand, the electrostatic latent image forming member 118
(FIG. 3) is grounded and electrically connected indirectly between current collection member 180 and current collection member 184.

When the above-described circuit configuration shown in FIG. 4-E is used in the electrostatic latent image developing device 102 shown in FIG. 3, a special power source is used for the charging DC voltage and the developing bias DC voltage. It will be clear that the same effects as those obtained when using the power supply circuit shown in FIG. 4-B can be obtained without the need to do so.

[Brief explanation of drawings]

FIG. 1 is a simplified sectional view showing a first specific example of an electrostatic latent image developing device constructed according to the present invention. Second
The figure is a simplified partially cutaway perspective view of the electrostatic latent image developing device shown in FIG. 1. FIG. 3 is a simplified sectional view showing a second specific example of an electrostatic latent image developing device constructed according to the present invention. Figures 4-A to 4-E are
4 is a circuit diagram showing a power supply circuit that can be used in combination with the electrostatic latent image developing device shown in FIG. 3. FIG. 2 and 102...electrostatic latent image developing device, 4 and 1
04... Developer holding member, 6 and 106... Developer container, 12 and 112... Opening of developer container,
14 and 114...developer, 16 and 116...
Development area, 18 and 118...electrostatic latent image forming member,
22 and 122...Charging member, 26...Upstream edge of opening of developer container, 32...Peeling member, 140...
...Switch mechanism.

Claims (1)

[Scope of Claims] 1. A developer holding member having a surface that can be moved through an endless movement path, and a developer container having an opening formed in a portion facing a part of the movement path, A downstream edge of the opening of the developer container located on the downstream side when viewed in the moving direction of the surface of the developer holding member is at least partially formed of an elastic material, and a free end is formed of a material that is elastic. The developer holding member is defined by a charging member that is brought into pressure contact with the surface of the member, and includes a one-component developer consisting only of toner particles that can retain the charge contained in the developer container. In an electrostatic latent image developing device of the type in which the developer is held and charged on the surface of the developer holding member and is carried to a development area by movement of the surface of the developer holding member to be applied to the electrostatic latent image to be developed; The upstream edge of the opening of the developer container, which is located on the upstream side when viewed in the moving direction of the surface of the developer holding member, is located at defined by a free end of a piece extending downwardly and downstream viewed in the direction of movement of the surface of the developer holding member at an angle α of 10°≦α≦50°; Positioned so as to be close to or in contact with the surface of the developer holding member on the downstream side of the uppermost part of the movement path of the surface of the developer holding member as viewed in the moving direction of the surface of the developer holding member. An electrostatic latent image developing device characterized by: 2. The developer has a specific resistance of 10 ¹² Ω·cm or more, the specific resistance of at least the surface layer of the developer holding member is smaller than the specific resistance of the developer, and the specific resistance of the charging member is smaller than the specific resistance of the developer. The electrostatic latent image developing device according to claim 1, wherein the resistivity is equal to or lower than that of at least the surface layer of the agent holding member. 3. The electrostatic latent image developing device according to claim 2, wherein the developer has a specific resistance of 10 ¹⁴ Ω·cm or more. 4 The specific resistance of at least the surface layer of the developer holding member is smaller than the specific resistance of the developer, but 10 ³
The electrostatic latent image developing device according to claim 2 or 3, which has a resistance of Ω·cm or more. 5. The developer holding member includes a metal support base and a surface layer mounted on the support base, and the surface layer is made of a material containing at least 10% silicone rubber by weight and has a diameter of 100 μm or more. The electrostatic latent image developing device according to any one of claims 1 to 4, which has a thickness. 6. The surface of the surface layer is dotted with high resistance parts formed from a material having a resistivity larger than that of the surface layer with a distribution degree of 50 meshes to 800 meshes. The electrostatic latent image developing device according to scope 5. 7. The thickness of the high resistance part is 500 μm or less,
An electrostatic latent image developing device according to claim 6. 8. The charging member is made of spring steel.
An electrostatic latent image developing device according to any one of claims 1 to 7. 9. The electrostatic latent image developing device according to claim 8, wherein the spring steel has an oxide film. 10. The electrostatic latent image developing device according to any one of claims 1 to 9, wherein the developer holding member is constituted by a rotationally driven roller. 11 The developer holding member has a surface that moves in the development area in the same direction as the moving direction of the surface of the electrostatic latent image forming member on which the electrostatic latent image to be developed is formed, and where the electrostatic latent image is formed. of the moving speed of the surface of the member
11. The electrostatic latent image developing device according to claim 10, which is rotatably driven to move at a moving speed of 1.5 to 5 times. 12. The electrostatic latent image developing device according to claim 10 or 11, wherein the developer holding member is continuously moved back and forth in the direction of its rotational axis. 13. A peeling member is disposed in the developer container to rub the surface of the developer holding member in a region within the opening to peel the developer from the surface of the developer holding member. The electrostatic latent image developing device according to any one of the ranges 1 to 12. 14. Electric means is provided for applying a DC voltage between the charging member and the surface of the developer holding member to charge the developer held on the surface of the developer holding member, The electric means includes a changeover switch mechanism capable of selectively reversing the polarity of the DC voltage applied between the charging member and the surface of the developer holding member. The electrostatic latent image developing device according to any one of items 1 to 13.