JP2000206783A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of obtaining a high-quality image over a long term by reducing the contact pressure of a layer regulating member to a developer carrier and forming a uniform and thin toner layer on the developer carrier. SOLUTION: A developer carrier 1 carrying the toner layer on its surface and feeding it to a developing area is disposed, and a layer forming member 3 is provided to come in contact with the surface of the carrier 1. By grinding the surface of the carrier 1, the average inclination (θa) of surface roughness is made smaller than 2.0 deg. and the average peak interval (Sm) of the surface is set to >=50 μm. The contact pressure of the member 3 to the carrier 1 is set to about 1 to 10 gf/cm. The surface of the carrier 1 is provided in such a way becomes near to a comparatively flat state and the toner thin layer is formed nearly uniformly on the carrier 1 by bringing the member 3 into contact with the carrier 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an electrophotographic image forming apparatus such as a copying machine or a printer, for selectively transferring toner to a latent image by a difference in electrostatic potential to visualize the developing device. .

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus such as a copying machine or a printer, an electrostatic latent image is formed on an image carrier,
The toner is selectively transferred to a visible image, and then the toner image is transferred to a recording sheet or the like.

As a developing device for visualizing an electrostatic latent image on the image carrier, for example, a developing device using a non-magnetic one-component developer is known. This developing device transports the toner onto the developer carrier, forms a toner layer on the developer carrier by a layer regulating member such as a blade, and imparts a predetermined polarity to the toner due to friction between the toner and the layer regulating member. Charge. Then, a bias voltage is applied between the developer carrier and the image carrier to form an electric field in a region facing the developer carrier, and the toner charged by the action of the electric field is transferred to an image area on the image carrier to be static. Visualize the latent image.

Conventionally, as the developer carrying member, a metal roll of stainless steel, aluminum, or the like, or a roll having a coat layer on the metal roll for controlling charge and controlling resistance has been used. The surface is roughened by a sandpaper method, a bead blast method, a sandblast method, a chemical etching method or a combination of these methods. In this way, the surface of the developer carrier is roughened to prevent uneven conveyance and a decrease in the amount of conveyance, and a uniform layer is formed by pressing the layer regulating member against the surface of the developer carrier. .

In addition, if the friction between the toner and the layer regulating member is insufficient, poorly charged toner remains in the toner layer and causes image disturbance. The member is pressed against the surface of the developer carrier with a strong pressure. When the layer regulating member is pressed with a strong pressure as described above, the toner on the developer carrier is scraped off, so that the toner is roughened so as to be easily caught on the surface of the developer carrier, and the required surface roughness is reduced. We are trying to secure.

[0006]

However, the conventional developing device as described above has the following problems. In the developing device, when the electrostatic latent image on the image carrier is visualized with the toner, the toner needs to be uniformly charged to a desired polarity, but the blade is pressed against the surface of the developer carrier. When the toner is frictionally charged, if the toner layer on the developer carrying member is thick, the toner in the lower layer may not be sufficiently charged. At the time of development, if toner of a desired polarity is mixed with toner of the opposite polarity, the latent image portion that should not be developed is developed, causing image disturbance.

In the conventional layer formation in the non-magnetic one-component developing system, charging is performed by friction between the toner and the blade, and the blade is applied to the developer carrier so that both are sufficiently contact-charged. It is necessary to increase the contact pressure. However, when the blade pressure increases, the toner scraping force also increases, and the surface of the developer carrier is roughened in order to supply a sufficient amount of toner to the developing area, thereby obtaining a necessary transport amount. Also, when the pressure applied to the toner increases, the stress applied to the toner also increases, and external additives used for charge control and fluidity control are embedded in the toner, and the performance such as chargeability and fluidity deteriorates. This causes image quality degradation.

Further, when a developer carrying member whose surface is roughened by a sandpaper method, a bead blasting method, a sand blasting method, a chemical etching method or a combination thereof, the developer carrying material is subjected to a layer forming cycle. There is a problem that the amount of toner on the body varies. That is, the toner amount in one cycle (when there is no toner on the developer carrier before supply), two cycles (when the toner in the first cycle remains without being consumed before supply), and the toner amount in the subsequent cycles Was measured, it was found that the toner amount in the first cycle was larger than the toner amount in the second and subsequent cycles. According to our experiments,
In the case where the conventional roughened developer carrier is used, for example, as shown by a dotted line in FIG. 16, the amount of toner on the developer carrier decreases from the first to the fifth cycle. When compared with the fifth cycle, the toner amount is reduced by about 10%.

Due to such cycle characteristics, when solid development is performed after the development of a solid black patch, the amount of toner in the portion where the patch is developed in the next layer formation cycle is larger than in other portions. As shown in FIG. 19A, only a part of the image is developed densely. FIG. 19B illustrates the state of the surface of the developer carrier at that time. As shown in this figure, on the surface of the developer carrying member, the amount of toner in the portion where the toner was consumed after being developed in the previous cycle is increased.

Another problem is that the surface of the developer regulating member is roughened so that the surface of the layer regulating member that comes into contact therewith is shaved. Then, a toner having a small particle diameter is clogged in the shaved portion, so that the toner is fixed, and there is a problem that the image is deteriorated such that a streak is generated in the toner layer.
Conventionally, an elastic body such as rubber is used for a portion of the layer forming member that comes into contact with the developer carrying member. However, since the layer is always in contact with the developer carrying member, the toner partially adheres, and When the toner layer is formed on the carrier, the toner is dammed, which causes stripe unevenness.

Further, a coating agent for more uniformly charging the toner may be applied to a portion where the layer regulating member comes into contact with the developer carrier, but the coating is applied by contact with the developer carrier. Even if peeling, streaking, etc. do not occur, an image disorder may occur due to poor charging of the toner.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce the contact pressure of a layer regulating member and to form a uniform and thin toner layer on a developer carrying member. An object of the present invention is to provide a developing device that can stably obtain a high-quality image for a long time by forming the developing device.

[0013]

According to a first aspect of the present invention, there is provided an image forming apparatus, comprising: an image carrier having an electrostatic latent image formed on a surface thereof; A developer carrier rotatably supported, and a layer forming member that is in contact with or pressed against the surface of the developer carrier to form a developer layer on the surface of the developer carrier, wherein the developer carrier A developing device that carries and transports a developer layer on the peripheral surface of the body, and transfers the toner to the image carrier at a position facing the image carrier and the developer carrier to visualize the electrostatic latent image In, the contact pressure of the layer forming member to the developer carrier,
It is set to 20 gf / cm or less, and an average inclination (θa) of the surface roughness of the developer carrying member is smaller than 2.0 degrees.

Here, the average inclination (θa) is, as shown in FIG. 14, expressed by the average value of the angle formed by the average line of the portion extracted by the measured length L from the cross-sectional curve and the cross-sectional curve. Is a value obtained by the following equation.

(Equation 1)

The average inclination (θa) indicates the average inclination angle of the irregularities on the surface of the developer carrier, and is one of the parameters for evaluation such as the degree of scattering of reflected light. is there. Further, the surface of the developer carrying member includes a surface close to a flat surface as long as it can be actually processed by a method such as polishing.

The contact pressure of the layer-forming member with the developer carrier may be 20 gf / cm or less. In this case, the case where the pressure hardly acts is included. This contact pressure
Considering the state of formation of the toner layer, 1 gf / cm to 10 g
f / cm is more preferred.

In such a developing device, the average slope (θa) of the surface roughness of the developer carrier is set to be smaller than 2.0 degrees, and the surface of the developer carrier is The number of small grooves is smaller than that of the carrier, and the state becomes relatively gentle. In such a developer carrier, for example, there is no toner on the developer carrier in the first cycle of layer formation, and toner remains on the developer carrier in the second cycle of layer formation without being consumed. In this case, the amount of toner in the first cycle and the amount of toner in the second and subsequent cycles are stabilized, as shown by the solid line in FIG. This is presumably because the surface of the developer carrying member is relatively gentle, so that the surface state becomes the same as the case where the toner is loaded even in the first cycle, and the amount of adhered toner is stabilized. Therefore, even when the solid development is performed after the development of the black solid patch, the toner amount in the portion where the patch is developed in the next layer forming cycle is prevented from increasing compared to the other portions, and the uniformity without density unevenness is prevented. An image is obtained.

Further, in the above-mentioned developing device, the contact pressure of the layer forming member with the developer carrier is set to 20 gf / cm or less, so that a thin toner layer can be formed almost uniformly on the developer carrier. It becomes possible. This is for the following reasons.

In the conventional developing device, the contact pressure of the layer forming member is increased to apply electric charge to the toner at the time of forming the layer, and the surface of the developer supporting member is cleaned so that the toner on the developer supporting member is not scraped off. Although the surface was roughened, in the present invention, the contact pressure of the layer forming member is reduced, and the toner is not scraped off even if the surface of the developer carrying member is made smooth.
A substantially uniform thin layer of toner is stably formed on the developer carrier. At this time, since the toner layer is thin, most of the toner comes into contact with the layer forming member, and the toner is almost uniformly charged. Therefore, the toner of the opposite polarity does not remain on the developer carrier after the layer is formed, and the occurrence of image quality deterioration such as background fogging during development is prevented. Further, since the contact pressure of the layer forming member is small, deterioration of the developer is prevented, and good image quality can be obtained over a long period.

According to a second aspect of the present invention, in the developing device according to the first aspect, an average interval between peaks (Sm) of the surface of the developer carrier is 50 μm or more.

Here, the average mountain interval (Sm) is defined as shown in FIG.
As shown in the figure, it is expressed by the average value of the interval from the point going from the peak to the valley to the crossing point going from the next peak to the valley, across the average line of the portion extracted by the measured length L from the sectional curve. It is a value obtained by the following equation.

(Equation 2)

In such a developing device, the average peak-to-peak interval (Sm) of the surface of the developer carrier is set to 50 μm or more. Small grooves are not densely formed like the body, and the surface is relatively flat. For this reason, the toner comes into stable contact with the developer carrier, and the amount of toner adhering to the developer carrier is stabilized. Therefore, even if the contact pressure of the layer forming member is set lower than in the related art, it is possible to form a uniform toner layer on the developer carrier.

According to a third aspect of the present invention, there is provided the developing device according to the first or second aspect, wherein the developer carrier is conductive. Such a developer carrier is desirably formed of a metal such as aluminum or stainless steel, for example. When the surface of the developer carrier is coated with an insulating layer, electric charges remain on the surface, and a uniform toner layer cannot be formed. It is considered that the mirror image plays a large role in conveying the toner, and by making the developer carrier conductive, a uniform toner layer can be formed on the developer carrier.

Further, as in the fifth aspect of the invention, the developer carrier may be a metal roll surface coated with a resistance layer. It is desirable to form a relatively thin layer of a low-resistance material as the resistance layer, whereby a uniform toner layer can be formed on the developer carrying member.

According to a sixth aspect of the present invention, in the developing device according to the first or second aspect, the developer carrier has a metal film or a resistor resin film formed endless. There is provided a developing device characterized in that the developing device is supported so as to be able to move around an endless peripheral surface. As described above, even when the developer carrier made of a metal film or a resistor resin film is used, the average slope (θa) and the average peak interval (Sm) of the surface roughness of the developer carrier are used.
Is set in the above range, a similar effect can be obtained.

According to a seventh aspect of the present invention, in the developing device according to any one of the first to sixth aspects, the toner carried on the developer carrier is a spherical toner. . In a conventional developer carrier, small grooves are densely formed on the surface. When spherical toner is used, the contact area between the toner and the developer carrier is reduced, and the force for holding the toner on the developer carrier is reduced. Is small.
On the other hand, in the present invention, since the surface of the developer carrying member is entirely flat and the contact area between the toner and the developer carrying member is large, a good layer formation is possible even when spherical toner is used. It can be performed.

According to an eighth aspect of the present invention, in the developing device according to any one of the first to seventh aspects, the developing device is provided downstream of the layer forming member in a circumferential direction of the developer carrier. It has a toner charging device for charging the toner carried on the agent carrier.

In the above invention, when a thin toner layer is formed on the developer carrying member by the layer forming member, the toner comes into contact with the layer forming member to give a charge of a desired polarity. After the formation, the toner is further charged by the toner charging device, so that the charge on the toner on the developer carrying member can be reliably applied. For this reason, the toner of the opposite polarity is prevented from being conveyed to the developing area by the circumferential movement of the developer carrying member, and a clearer image can be obtained.

According to a ninth aspect of the present invention, in the developing device according to any one of the first to eighth aspects, a portion of the layer forming member that contacts the developer carrier is formed of plastic. It is assumed that

By using plastic for the portion of the layer forming member that comes into contact with the developer carrying member, toner adhesion can be suppressed as compared with a conventionally used layer forming member that uses rubber for the contact portion. It is possible to form a uniform toner layer on the developer carrying member without stripe unevenness for a long period of time. It is considered that the reason why plastic is less likely to stick than conventionally used rubber is that the coefficient of friction of the surface of rubber is large in the case of rubber and the toner is easily caught. Incidentally, the plastic described in the above invention is mainly a thermoplastic resin, and particularly, O, N,
It has S and a benzene ring. The rubber is a vulcanized rubber, a thermoplastic elastomer, or the like that exhibits rubber-like elasticity.

According to a tenth aspect of the present invention, in the developing device according to any one of the first to ninth aspects, the layer forming member includes a conductive layer on a surface that does not contact the developer carrier. And a power supply for applying an alternating electric field between the conductive layer and the developer carrier.

In such a developing device, by applying an alternating electric field, the toner can be vibrated after passing through the layer forming member, and it is possible to form a uniform toner layer without fine lines or unevenness. Become. As this alternating electric field, for example, a sine wave as shown in FIG. 18A can be used, but it is preferable that a DC component is superimposed as shown in FIG. 18B. That is, by using the alternating electric field in which the DC component is superimposed on the AC component as in the invention according to claim 13, an effect is produced that the charged toner is attracted to the developer carrier. FIG.
A rectangular wave as shown in (c) may be used. In an actual developing device, apart from the alternating electric field for forming the layer,
Since an alternating electric field for developing the toner on the electrostatic latent image carrier is also applied, the bias actually applied to the developer carrier is a sum of these. The applied bias can be set as appropriate, such as a sine wave or a rectangular wave.

According to an eleventh aspect of the present invention, in the developing device according to the tenth aspect, the layer forming member has a thin metal film formed on a surface of the plastic film that does not contact the developer carrier. Shall be. The metal thin film can be provided by, for example, vapor deposition, and an alternating electric field can be applied through the metal thin film. When the entire member is formed of a plastic film, the processing is easier and the cost is lower than that of a metal material.

According to a twelfth aspect of the present invention, in the developing device according to the tenth aspect, the layer forming member is a metal plate member partially fixed and supported, and is adhered to the plate member. Plastic film. In such a layer forming member, since a metal plate-shaped member is used, it is difficult to be plastically deformed with time as compared with a case where a metal thin film is provided by vapor deposition or the like, and the contact pressure is kept substantially constant for a long period of time. Is possible. For example, a plastic film having an adhesive property on one side adhered to a metal plate member can be easily and inexpensively manufactured.

When the toner is vibrated by the AC bias as described above, a very large alternating electric field is required if a conventional thick rubber member is used as the layer forming member.
If a thin plastic film is used as in the invention of claim 11 or 12, a vibration effect can be obtained from a low voltage, and it is possible to prevent discharge to other parts of the device and save energy. .

According to a fourteenth aspect of the present invention, in the developing device according to any one of the tenth to thirteenth aspects, the alternating electric field has an AC component having a peak-to-peak voltage of 100.
It is assumed that V is set to V or more. By setting the peak-to-peak voltage of the AC component to 100 V or more, the toner vibrates sufficiently and the toner layer can be made substantially uniform.

According to a fifteenth aspect of the present invention, in the developing device according to the tenth aspect, the relationship between the frequency of the alternating electric field and the surface speed of the developer carrier is 10 Hz. / (Mm / sec) or more. The frequency of the AC bias is determined by the relationship with the surface speed of the developer carrying member.
When it is set to z / (mm / sec) or more, the speed of vibration is increased, and it is possible to prevent the toner layer from being uneven.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a developing device according to an embodiment of the invention described in claim 1, claim 2, claim 3 or claim 4. In this developing device, an opening is provided in a portion of a housing 9 in which a developer is accommodated and opposed to an image carrier 10, and a developer carrier that carries a non-magnetic one-component developer while carrying it on the surface is provided in this portion. 1 is provided. At a position facing the developer carrier 1, a supply roll 2 for supplying the developer to the developer carrier 1 and a layer forming member 3 for forming a thin layer of toner on the surface of the developer carrier are provided.
Further, a stirring member 4 for stirring the developer in the housing 9 is provided on the back side of the supply roll 2. Further, a power supply 5 for applying a developing voltage between the developer carrier 1 and the image carrier 10 is connected to the developer carrier 1.

The developer carrier 1 is made of an aluminum roll, and its surface is polished by a combination of sandblasting and chemical etching, so that the surface is relatively smooth and has no small grooves as shown in FIG. It is formed in a state (a state almost entirely flat). The surface of the developer carrier is formed such that the average slope (θa) of the surface roughness is smaller than 2.0 degrees and the average peak interval (Sm) is 50 μm or more.

The surface roughness of the developer carrying member 1 is measured by using Surfcom manufactured by Tokyo Seimitsu Co., Ltd. in the following manner. As shown in FIG. 3A, when the developer carrier 1 was rotated and the measurement stylus 11 was fixed for measurement, the measurement was not performed accurately due to uneven rotation of the developer carrier. As shown in FIGS. 3B and 3C, the measurement was performed by moving the stylus 11. In order to reduce measurement errors, the minimum measurement length is 2 mm
You have to do more. In this measurement, the measurement length was set to 10 mm, the cutoff value was set to 0.25 mm, the tip diameter of the stylus was set to 1 μm, and the measurement distance was set to be sufficiently large. In the method shown in FIG. 3B, it is difficult to measure a long range in the case of a developer carrier having a small diameter.
The measurement was performed by moving the stylus 11 by the method shown in FIG.

Conventionally, ten-point average roughness (Rz) has been used as a means for indicating the surface roughness of a developer carrier or the like, but the value changes when the measurement distance changes. It is not suitable as a means showing minute irregularities such as a developer carrier. Therefore, the present applicant uses the average inclination (θa) and the average peak interval (Sm) shown in FIGS. 14 and 15 as means for indicating minute surface irregularities, and sets these in the above range. The effect of the surface state of the developer carrier will be described later.

The layer forming member 3 has a thickness of 0.03-0.
Si rubber or EPDM on stainless steel leaf spring of about 3mm
The rubber is vulcanized and adhered, and is supported so as to be in contact with the surface of the developer carrying member 1. At this time, the contact pressure on the developer carrier 1 is 20 gf / cm or less, preferably 1 gf / cm or less.
It is set to be 0 to 1 gf / cm. Also,
A rubber having a hardness of 20 to 80 degrees can be used, and a rubber having a hardness of 30 to 60 degrees is particularly suitable.

The contact pressure of the layer forming member 3 was measured by an apparatus as shown in FIG. As shown in this figure, a pressure sensor 24 is provided so as to contact the bearing members 22 at both ends of the developer carrier 21, and the layer forming member 23 is pressed against the developer carrier 21, and the pressure sensor 24 23 were measured for contact pressure.

The contact pressure of the layer forming member 3 is 50 gf / c
If it exceeds m, the layer forming member scrapes off the toner on the developer carrying member, and a uniform toner layer cannot be formed. In the present embodiment, the contact pressure of the layer forming member 3 is set to 10 to 1 gf / cm, which is smaller than in the related art, so that a thinner toner layer is formed on the surface of the developer carrier 1. At this time, approximately one layer of the toner layer on the developer carrying member is in a state of being carried. Further, when the toner layer is formed, the layer forming member 3 is almost certainly in contact with the toner particles constituting the toner layer, so that the toner is charged substantially uniformly, and the toner of the opposite polarity is hardly mixed. . The layer forming member 3 may be a plastic film such as polyethylene or polystyrene having a thickness of about 0.05 to 0.5 mm.

The developer used in the above-mentioned developing device is a non-magnetic one-component toner, and a polarity controlling agent such as a pigment or a metal-containing azo dye is contained in various thermoplastic resins such as styrene resin, acrylic resin and polyester resin. Is dispersed, crushed and classified to a size of 3 to 20 μm, and a charge control agent is externally added. As the charge control agent, fine particles of about 0.1 μm or less such as silica, alumina, and titanium oxide which have been subjected to a hydrophobic treatment are used, and titanium oxide is more preferable. Further, a fluidity aid of the toner is externally added.

In such a developing device, the toner is stirred by the stirring member 4 in the housing 9, and the toner is supplied to the surface of the developer carrier 1 by the supply roll 2. The toner supplied to the developer carrier 1 passes through a contact portion with the layer forming member 2 by the rotation of the developer carrier 1, and a substantially uniform toner layer is formed on the surface of the developer carrier 1. The toner layer is conveyed to a position facing the image carrier 10 by rotation of the developer carrier 1, and the toner is carried on the image carrier by the action of an electric field formed between the developer carrier 1 and the image carrier 10. The image is transferred to an electrostatic latent image of the body 10 and is visualized.

In the developing device, the surface of the developer carrier 1 is relatively smooth and the contact pressure of the layer forming member 3 is set to be small. The toner can be uniformly formed, and the toner can be prevented from being deteriorated by the layer forming member 3.

Next, an experiment performed to confirm the effect of the developing device will be described. First, the result of examining the cycle characteristics of the amount of toner on the developer carrier when the toner layer is formed by changing the average inclination (θa) of the surface of the developer carrier will be described. FIG. 5 is a graph showing the relationship between the toner layer forming cycle and the amount of toner on the developer carrier when the average inclination (θa) is changed. In this experiment, the contact pressure of the layer forming member was 5 gf / cm
Is set to As shown in FIG. 5, when the value of θa decreases, the amount of toner on the developer carrier becomes substantially constant, and the cycle characteristics are improved.

FIG. 6 is a graph showing the relationship between the toner amount change rate ( _ΔTMAD ) and θa in the first cycle and the fifth cycle. The toner amount change rate ( _ΔTMAD ) is given by the following equation.

(Equation 3)

According to previous studies, Δ _TMAD <5.0%
It has been found that the image has no significant effect in the range of. Accordingly, FIG. 6 shows that the average inclination (θa) of the surface roughness of the developer carrying member is preferably in the range of θa <2.0 degrees.

Next, the average peak interval (Sm) of the developer carrying member
The result of measuring the amount of toner on the developer carrying member when is changed will be described. FIG. 7 shows the average mountain interval (Sm).
5 is a graph comparing the relationship between the amount of toner on a developer carrier and the amount of toner on a developer carrier. As shown in this graph, the toner amount on the developer carrier is Sm ≧ 50 μm
It can be seen that it becomes almost uniform in the range of.

Conventionally, the layer forming member has a thickness of 20 gf /
The toner layer was pressed against the developer carrying member at a contact pressure of about 15 cm, and when it was 15 gf / cm or less, the toner layer was disturbed, and a good toner layer could not be formed. On the other hand, in the present embodiment, it was confirmed that a good toner layer was formed even at 20 gf / cm or less. The contact pressure of the layer forming member is particularly preferably from 10 to 1 gf / cm, and it has been found that a substantially uniform thin layer of the toner can be obtained in this range. When the contact pressure of the layer forming member was 0.5 gf / cm or less, the pressure was weak and uniform layer formation was not performed.

From the above results, the average inclination (θa) of the surface of the developer carrying member is set to θa <2.0 degrees, and the average interval between peaks (Sm) is set to Sm ≧ 50 μm, thereby forming a weaker layer than the conventional one. It was found that a substantially uniform thin layer of toner could be formed on the developer carrying member by the contact pressure of the member.

Next, the results of a long-term running test using the developer carrier of the present embodiment and a conventional developer carrier will be described. The developer carrier of the present embodiment has a relatively smooth surface and few small grooves, as shown in FIG. 2 described above. On the other hand, the conventional developer carrier has a roughened surface by blasting or the like, and as shown in FIG. 8, small grooves are densely formed on the surface, so that the average inclination (θa) is large. Value.

When the cycle characteristics of the amount of toner on the developer carrier were measured, the developer carrier 1 of the present embodiment showed that the amount of toner on the developer carrier in the first cycle and the second and subsequent cycles was It was confirmed that the change was stabilized as compared with the conventional developer carrier 121. In addition, when a long-term running test was performed, the conventional developer carrier 12
In No. 1, the surface of the layer forming member is shaved by the rotation of the developer carrying member, and the toner adheres to that portion, causing a streak or the like. When used, it was confirmed that a uniform toner layer was formed over a long period of time.

In the above-described developing apparatus, an example in which a non-magnetic one-component developing system is used is shown. However, the same applies to a developing system in which a magnetic developer is held on a developer carrier by magnetic attraction. The effect can be obtained.

Next, a developing device according to an embodiment of the present invention will be described. In this developing device, instead of the developer carrier 1 of the developing device shown in FIG.
A developer carrier 31 having a peripheral surface covered with a coat layer 31b made of a resistor is used. The coat layer 31b is made of a material having a low resistance, such as a resin mixed with a conductive powder. This is because if the surface is coated with an insulating layer, electric charges remain on the surface and a uniform toner layer cannot be formed, and the thickness of the coat layer 31b is preferably smaller. . Also, the average surface inclination (θa) and the average peak interval (Sm)
Is set the same as the developer carrier 1 shown in FIG. The other structure of this developing device is the same as that of the developing device shown in FIG.

Regarding the conveyance of the toner on the developer carrying member, it is considered that the mirror image force, which is the force for holding the toner on the developer carrying member, plays a large role. By covering the developer carrying member with the low-resistance coating layer 31b as described above, electric charge is prevented from remaining, and a substantially uniform toner layer can be formed.

FIG. 10 is a schematic structural view showing a developing device according to an embodiment of the present invention. This developing device includes a developer carrier 41 having a film-like member formed endlessly, and is supported by supporting rolls 46 and 47 so as to be able to move around. The developer carrier 41 is made of a metal film such as aluminum, and has an average surface roughness slope (θa) of less than 2.0 degrees and an average surface interval (Sm) of 5 degrees.
It is formed so as to be 0 μm or more. The other structure of this developing device is the same as that of the developing device shown in FIG.

In such a developing device, as in the embodiment shown in FIG. 1, the amount of toner on the developer carrier after the first cycle and the second cycle and thereafter is small, and the cycle characteristics are stabilized. In addition, a long-term running test confirmed that a uniform toner layer was formed over a long period of time.

Next, a developing device according to an embodiment of the present invention will be described. In this developing device, as shown in FIG. 11A, a spherical toner 52 having a particle diameter of 3 to 20 μm is used as a developer. 0.1 μm or less fine particles such as silica, alumina, and titanium oxide subjected to hydrophobic treatment are externally added as a charge control agent to the surface of the spherical toner, and titanium oxide is more preferable. Further, a fluidity aid of the toner is externally added. Further, as the developer carrying member 51, the same as the developer carrying member used in the developing device shown in FIG. 1 is used. The other structure of this developing device is the same as that of the developing device shown in FIG.

In the conventional developer carrier, when the spherical toner 152 is used as shown in FIG. 11B, the contact area between the toner and the developer carrier 151 is small, and the toner is transferred to the developer carrier 151. The image power, which is the holding force, is small. On the other hand, in the present embodiment, as shown in FIG.
Since the contact area between the toner 52 and the developer carrying member 51 is larger than in the related art, a toner layer can be favorably formed on the developer carrying member even when spherical toner is used.

FIG. 12 is a schematic structural view showing a developing device according to an embodiment of the present invention. This developing device includes, in addition to the developing device shown in FIG. 1, a toner charging device that charges a toner layer formed on the developer carrying member 61 downstream of the layer forming member 63 in the circumferential direction of the developer carrying member 61. A device 66 is provided.

This toner charging device 66 is shown in FIG.
As shown in FIG. 5, discharge electrodes 71 and electric field control electrodes 72 are alternately arranged at equal intervals on an insulating substrate 73. The discharge electrodes 71 are formed of a conductive layer 71a and a semiconductive layer covering the surface thereof. 71b. And
A potential equal to or higher than the discharge start potential is applied to the discharge electrode 71 from the power supply 74, and a potential between the developer carrier 61 and the discharge electrode 71 is applied to the electric field control electrode 72 from the power supply 75. In such a toner charging device 66, the discharge electrode 71
A high electric field is generated in a minute space between the electric field control electrode 72 and the electric field control electrode 72, and an ionization state is formed in this minute space. An induced electric field formed between the developer carrier 61 and the developer carrier 61 guides the toner layer on the developer carrier. The other structure of the developing device is the same as that of the developing device shown in FIG.

In the developing device as described above, a substantially uniform toner layer is formed on the developer carrier 61 by the layer forming member 63, and when this toner image passes through a position facing the toner charging device 66, The toner layer is charged to a substantially uniform polarity. Although the toner is charged by the contact friction with the layer forming member 63, a clearer image can be obtained by more surely applying a charge of a desired polarity to the toner by the toner charging device 66. Further, the toner charging device 66 does not charge the toner only by friction with the layer forming member 63.
, The contact pressure of the layer forming member can be further reduced, and the deterioration of the toner can be prevented for a long period of time.

Next, the result of incorporating the developing device of the present embodiment into the image forming apparatus shown in FIG. 13 and performing a print test will be described. The image forming apparatus used in this experiment includes an image carrier 101 that irradiates image light after uniform charging and forms a latent image on the surface due to a difference in charging potential,
A charging device 102 for charging the surface of the image carrier 101 almost uniformly around the image carrier 101, and an image carrier 101
An exposure device 103 that irradiates image light corresponding to image information on the surface of the image forming apparatus, and a toner image storage device that accommodates toners of different colors and visualizes a latent image formed on the image carrier 101 by attaching toner of each color. Developing devices 104a, 104b,
The image forming apparatus includes transfer devices 104 c and 104 d and a transfer device 106 that transfers the toner image formed on the image carrier 101 onto the image receiving member 105. Further, a cleaning device 107 for cleaning the toner remaining on the image carrier 101 after the transfer, and a fixing device 1 for fixing the toner image transferred onto the image receiver 105
08.

The developing devices 104a, 104b, 104
Reference numerals c and 104d each have the same configuration as the developing device shown in FIG. 1, and include a developer carrier 111 that carries and transports yellow, magenta, cyan, and black toners, respectively. As the image carrier 101, a Se-based photoconductor or an organic photoconductor is used, and the image carrier 101 and the developer carrier 111 may be in contact with each other, or 100 to 400.
They may be opposed with a gap of about μm.

The conditions of this experiment are as follows. Image carrier Negatively charged organic photoreceptor Process speed 300 mm / sec Developer carrier Aluminum roll of φ20 mm Supply roll Roll of φ10 mm semiconductive sponge material Layer forming member SUS303, 0.10 mm leaf spring and 1 mm thick EP Adhesion of DM rubber Adhesion pressure: approx. 5 gf / cm, rubber hardness: 50 Latent image potential: -100 V Blank paper potential: -350 V Toner Pigment dispersed in styrene resin, crushed and classified to 7 μm size

As a result of the print test under the above conditions, it was confirmed that even when about 30,000 copies were made, no image disturbance occurred and high quality prints could be obtained. It was also confirmed that toner spillage and the like were more stable in the high-speed range than in the past.

For comparison, a similar print test was conducted with the contact pressure of the layer forming member set to 20 gf / cm. As a result, image disturbance due to toner deterioration occurred in about 4,000 copies. Further, when the contact pressure of the layer forming member was set to 10 gf / cm, image disorder occurred in about 8,000 copies. When the contact pressure of the layer forming member was about 5 gf / cm, an experiment was conducted while adding toner every 8,000 sheets, but no image disturbance occurred. From the results of this experiment, it was confirmed that the developing device of the present embodiment hardly deteriorated the toner due to the embedding of the external additive or the like and was excellent in maintainability.

Further, a print test was also conducted on the developing device shown in FIG. 12 in the same manner as described above, and it was confirmed that a good image could be obtained for a long period without occurrence of background fogging or generation of toner of opposite polarity. In addition, since the toner is charged by the toner charging device without charging the toner only by friction with the layer forming member, the contact pressure of the layer forming member can be further reduced, and the deterioration of the toner is hardly caused. No generation was observed, and it was confirmed that the maintainability was excellent.

FIG. 17 shows a developing device and a layer used in the developing device according to an embodiment of the present invention described in claim 9, claim 10, claim 12, claim 13, claim 14 or claim 15. It is a schematic structure figure showing a forming member. This developing device is different from the developing device shown in FIG.
21, the supply roll 122, the stirring member 124 and the like have the same configuration, but the configuration of the layer forming member 123 is different. As shown in FIG. 17B, the layer forming member 123 is formed by bonding a plastic film 123b to a metal plate member 123a so that the surface of the plastic film contacts the developer carrier 121. It is supported by. A power supply 126 is connected to the metal plate member 123a,
A bias in which a DC component is superimposed on the component is applied. At this time, the process speed (speed of the developer carrying member 121) is set to 300 mm / sec.
The peak-to-peak voltage (V _PP ) of the C component is 500 V, and the frequency is 4.5 kHz. Thereby, the relationship between the frequency of the AC component and the process speed of the developer carrier 121 is set to 10 Hz / (mm / sec) or more.

In such a developing device, the developer carrier 1
When the toner on the layer 21 passes the position facing the layer forming member 123, the toner is regulated and a toner layer is formed, and the alternating electric field applied between the layer forming member 123 and the developer carrier 121 causes The toner vibrates. Fine stripes and unevenness are smoothed by the vibration of the toner, and a substantially uniform toner layer is formed. Further, by superimposing the DC component, the toner is attracted to the developer carrying member 121, and scattering of the toner is prevented. Also, as described above,
By appropriately setting the relationship between the peak-to-peak voltage (V _PP ) of the component, the frequency of the AC component, and the process speed of the developer carrying member 121, sufficient vibration of the toner can be obtained.

Next, the results of an experiment in which the developing device shown in FIG. 17A was used to investigate the maintainability of the developer carrier and the layer forming member and the state of formation of the toner layer will be described. The developing device used in this experiment is set so that the toner is not consumed unlike the actual case. For this reason, it is greatly affected by the toner deterioration, and it is possible to confirm the image deterioration in a shorter time than actual. As shown in Table 1, as a layer forming member, a 1 mm thick EPD was placed on a 0.1 mm SUS plate.
M rubber and 5 mm on a 0.1 mm SUS plate
FIG. 1 shows an example in which a polyester film having a thickness of 0 μm is adhered and a developer carrier is used.
1 used in the embodiment shown in FIG. Table 1 shows the results of comparing the occurrence time of these white streaks.

[0075]

[Table 1]

As shown in Table 1, the use of the developer carrier of the embodiment shown in FIG. 1 shows that the use of a conventional rubber material as the layer forming member shows twice or more the maintainability. Understand. Furthermore, it was confirmed that the use of a SUS plate on which a film was attached as the layer-forming member exhibited three times or more the maintainability as compared with the conventional rubber-applied one. When the layer is formed while applying an alternating electric field to the layer forming member, the toner vibrates after the layer is formed. However, streaks were eliminated and a uniform toner layer could be obtained.

Further, in place of the above-mentioned layer forming member, a thickness of 0.
The same experiment was performed using a metal film deposited on the back surface of a 25 mm plastic film. This layer forming member is also one embodiment of the invention described in claim 11. It was confirmed that the same effect as in the above experiment was obtained when this layer forming member was used.

Next, an experiment was conducted to examine the state of formation of the toner layer by changing the relationship between the peak-to-peak voltage (V _pp ) of the AC bias applied to the layer forming member and the frequency and the process speed of the developer carrier. . As a result, it was confirmed that unless the AC bias peak-to-peak voltage (V _pp ) was 100 V or more, the toner did not vibrate sufficiently, and the toner leveling effect was not obtained. Further, it was confirmed that the relationship between the frequency and the process speed of the developer carrying member was not 10 Hz (mm / sec) or more, and the speed of the vibration was slow, and the toner layer became uneven.

[0079]

As described above, in the developing device according to the present invention, a substantially uniform toner layer can be formed on the developer carrier, and the amount of toner in each layer forming cycle can be stabilized. And a good image can be formed over a long period of time. Further, by lowering the contact pressure of the layer forming member with the developer carrying member, the deterioration of the developer is reduced, and the life of the developing device can be extended. Further, by using a plastic film as a layer forming member, or by applying an alternating electric field between the layer forming member and the developer carrier,
The unevenness of the toner layer can be eliminated, and a more uniform toner layer can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a developing device according to an embodiment of the present invention described in claim 1, 2, 3, or 4;

FIG. 2 is a schematic diagram showing a surface state of a developer carrier used in the developing device.

FIG. 3 is an explanatory view showing a method for measuring the surface roughness of a developer carrying member used in the developing device.

FIG. 4 is a schematic configuration diagram showing an apparatus for measuring a contact pressure of a layer forming member used in the developing device.

FIG. 5 is a graph showing a relationship between a layer forming cycle in the developing device and a toner amount on a developer carrying member.

FIG. 6 is a graph showing a relationship between an average inclination (θa) of a surface roughness of a developer carrying member used in the developing device and a change rate of a toner amount on the developer carrying member.

FIG. 7 is a graph showing a relationship between an average mountain interval (Sm) of a developer carrier used in the developing device and a toner amount on the developer carrier.

FIG. 8 is a schematic diagram showing a surface state of a developer carrier which is a comparative example of the developer carrier used in the developing device.

FIG. 9 is a partially enlarged view of a developer carrier used in the developing device according to an embodiment of the present invention described in claim 1, 2 or 5;

FIG. 10 is a schematic configuration diagram showing a developing device according to an embodiment of the present invention described in claim 1, 2 or 6.

FIG. 11 is a partially enlarged view of a developing device according to an embodiment of the invention described in claim 1, claim 2, or claim 7,
FIG. 3 is a schematic configuration diagram illustrating a state of adhesion of a toner on a developer carrying member.

FIG. 12 is a schematic configuration diagram showing a developing device according to an embodiment of the present invention described in claim 1, 2 or 8;

13 is a schematic configuration diagram illustrating an example of an image forming apparatus using the developing device illustrated in FIG.

FIG. 14 is a view showing the average inclination (θa) of the surface roughness of a developer carrying member used in the developing device of the present invention.

FIG. 15 is a diagram showing an average peak interval (Sm) of the surface of a developer carrying member used in the developing device of the present invention.

FIG. 16 is a graph comparing the relationship between the development cycle in the developing device of the present invention and the amount of toner on the developer carrier with that of a conventional developing device.

FIG. 17 shows a developing device according to an embodiment of the present invention according to claim 9, claim 10, claim 12, claim 13, claim 14 or claim 15, and a layer forming member used in the developing device. FIG.

18 is a diagram illustrating an example of a bias applied between a layer forming member and a developer carrier of the developing device illustrated in FIG. 17;

FIG. 19 is a diagram illustrating a problem in a conventional developing device, and is a diagram illustrating a state of adhesion of toner on a developer carrier and a state of an image.

[Explanation of symbols]

 1, 31, 41, 51, 61, 121 Developer carrier 2, 42, 62, 122 Supply roll 3, 43, 63, 123 Layer forming member 4, 44, 64, 124 Stirring member 5, 125 Power supply 9, 129 Housing 10 image carrier 11 stylus 21 developer carrier 22 bearing member 23 layer forming member 24 pressure sensor 46, 47 support roll 52 toner 66 toner charging device 71 discharge electrode 72 electric field control electrode 73 insulating substrate 74 power supply 75 power supply 101 image Carrier 102 Charging device 103 Exposure device 104 Developing device 105 Image receiver 106 Transfer device 107 Cleaning device 108 Fixing device 111 Developer carrier 126 Power supply

Continued on the front page F term (reference) 2H005 AA15 FA06 FA07 2H073 AA01 BA04 BA25 CA02 CA13 2H077 AB03 AC04 AD02 AD06 AD13 AD17 AD23 AD36 EA13 EA14 EA15 EA16 FA01 FA13 FA25

Claims (15)

[Claims] 1. A developer carrier which is provided close to or in contact with an image carrier on which an electrostatic latent image is to be formed, and whose peripheral surface is rotatably supported, A layer forming member that forms a developer layer on the surface of the developer carrying member, which is in contact with or pressed against the developer carrying member, and carries and transports the developer layer on the peripheral surface of the developer carrying member;
A developing device for transferring the toner to the image carrier at a position facing the image carrier and the developer carrier to visualize the electrostatic latent image, wherein the layer forming member contacts the developer carrier; Pressure is 20
gf / cm or less, and the average slope (θa) of the surface roughness of the developer carrying member is:
A developing device characterized by being smaller than 2.0 degrees. 2. The developing device according to claim 1, wherein an average interval between peaks (Sm) of the surface of the developer carrier is 50 μm or more. 3. The developing device according to claim 1, wherein the developer carrier is conductive. 4. The developing device according to claim 1, wherein the developer carrying member is formed of a metal. 5. The developing device according to claim 1, wherein the developer carrier has a metal roll surface coated with a resistance layer. 6. The developer carrying member is a metal film or a resistor resin film formed into an endless shape, and is supported so that the endless circumferential surface can be moved around. The developing device according to claim 1 or 2, wherein 7. The developing device according to claim 1, wherein the toner carried on the developer carrier is a spherical toner. 8. The image forming apparatus according to claim 1, further comprising a toner charging device configured to charge the toner carried on the developer carrying member downstream of the layer forming member in a circumferential direction of the developer carrying member. The developing device according to any one of claims 1 to 7. 9. The developing device according to claim 1, wherein a portion of the layer forming member that comes into contact with the developer carrier is formed of plastic. 10. The layer forming member has a conductive layer on a surface not in contact with the developer carrier, and has a power supply for applying an alternating electric field between the conductive layer and the developer carrier. 10. The method according to claim 1, wherein:
The developing device according to any one of the above. 11. The developing device according to claim 10, wherein the layer forming member is formed by forming a thin metal film on a surface of a plastic film that does not contact the developer carrier. 12. The layer forming member according to claim 10, wherein the layer forming member has a metal plate member partially fixed and supported, and a plastic film attached to the plate member. Developing device. 13. The alternating electric field according to claim 10, wherein a DC component is superimposed on an AC component.
The developing device according to claim 12. 14. The alternating electric field according to claim 1, wherein a peak-to-peak voltage of an AC component is 100 V or more.
The developing device according to any one of claims 0 to 13. 15. The relationship between the frequency of the alternating electric field and the surface speed of the developer carrier is 10 Hz / (mm / sec).
The developing device according to any one of claims 10 to 14, wherein c) or more.