JP2002365904A - Development machine and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a development machine and an imaging device, capable of avoiding image defects such as longitudinal stripes or uneven density on image and superior formation of the image by toner from being stuck to a conductive developer regulating member and the developer carrier, so that a toner thin layer is stably formed on a developer carrier. SOLUTION: This development machine is provided with a voltage-applying means 32 generating electric field between the developer carrier 11 and the conductive developer regulating member 12, and develops an electrostatic latent image formed on an image carrier 21 with developer 15 carried on the developer carrier 11, so as to form a developer image on the image carrier 21. In the developing device and the imaging device equipped with the developing device, the applying means 32 generates alternating electric field between the developer carrier 11 which rotates and the regulating member 12, when the image is not being formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for developing an electrostatic latent image formed on a latent image carrier such as an electrophotographic photosensitive member or an electrostatic recording derivative, and a copy provided with the developing device. The present invention relates to an electrophotographic image forming apparatus such as a printer, a facsimile, or an image forming apparatus such as an electrostatic recording apparatus.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying apparatus, an image recording apparatus, a printer, and a facsimile, an electrostatic latent image formed on a latent image carrier such as an electrophotographic photosensitive member or an electrostatic recording dielectric is used. The image is developed by a developing device and visualized as a developer image (toner image). As one of such developing devices, various developing devices using a non-magnetic toner developer have been proposed and put into practical use.

For example, as shown in JP-A-54-43038, a rubber or metal developing blade as a developer regulating member is brought into contact with the surface of a developing sleeve as a developer carrier, A thin layer of toner is formed on the developing sleeve by regulating the passage between the contact portion of the developing blade and the developing sleeve by passing non-magnetic toner.
In addition, there is a developing device that imparts a sufficient triboelectric charge to the toner by friction at a contact portion.

[0004] The developing device using the above-mentioned non-magnetic toner requires a separate toner supply member for supplying the toner onto the developing sleeve. Because, in the case of magnetic toner,
This is because toner can be supplied onto the developing sleeve by the magnetic force of the magnet in the developing sleeve, but in the case of non-magnetic toner, toner cannot be supplied by the magnetic force.

That is, as shown in FIG. 11, a non-magnetic one-component developing device is a developing container 1 containing a non-magnetic toner 15.
6, a developer supply roller 14 having a developer sleeve 11 and a developing blade 12 in the opening thereof and abutting against the developing sleeve 11 at a position upstream of the developing blade 12 in the rotation direction of the developing sleeve 11 in a developing container 16. By rotating this in the direction E (the direction in which the facing portion moves in the opposite direction) with respect to the developing sleeve 11 rotating in the direction D,
The nonmagnetic toner 15 is supplied and carried on the developing sleeve 11.

The toner 1 carried on the developing sleeve 11
5 is then sent to a contact portion with the developing blade 12 with the rotation of the developing sleeve 11, where it is thinned, and then conveyed to a developing unit facing the photosensitive drum 21, and Used for developing the electrostatic latent image. The toner 15 remaining without being provided on the developing sleeve 11 is returned into the developing container 16 by the developing sleeve 11, peeled off from the surface of the developing sleeve 11 by the toner supply roller 14, and then again by the toner supply roller 14. The supply to the developing sleeve 11 is repeated.

Further, as a method for efficiently providing the electric charge to the toner 15, there is a method of externally adding a charge auxiliary agent to the toner base particles. As the charge auxiliary agent, fine particles having the same polarity as the toner base particles in the charging series are used. Further, in order to further charge the fine particles having the same polarity as the toner base particles, fine particles having the opposite polarity to the toner base particles are used. In order for this action to be performed effectively, the particle diameter is desirably in the order of toner base particles> fine particles having the opposite polarity to the toner base particles> fine particles having the same polarity as the toner base particles. Such a method of externally adding two or more types of fine particles to toner base particles to activate charging of the toner is generally applied.

[0008] In recent years, the demand for images in computers and the like that handles images in digitized form has increased, and accordingly, higher definition and higher quality images have been demanded, and further, lower cost image forming apparatuses have been demanded. .

In order to meet such demands, it is desirable to use a thin metal plate which is easier and cheaper to process than a rubber product which is relatively difficult to process and expensive, as a material of the developing blade 12. It is possible to achieve both low cost and high image quality of the forming apparatus.

[0010]

However, FIG.
When the developing blade 12 and the developing sleeve 11 are set to the same potential by using a metal thin plate as the developing blade 12 as described in
The toner 15 adheres to the developing blade 12 at the nip portion where the toner and the developing sleeve 11 come into contact with each other, thereby hindering uniform toner coating in the longitudinal direction on the developing sleeve 11, resulting in a vertical streak-like defect as an image. Has occurred.

Further, as shown in FIG. 1, the developing blade 12 is connected to a bias power source 32 which is a voltage applying means in order to eliminate toner sticking on the developing blade 12, and the developing sleeve 11 is connected to a bias power source 31 for applying a developing bias. And as a result of providing a potential difference between the developing blade 12 and the developing sleeve 11, the fixing on the developing blade 12 disappeared, but the toner was fixed on the developing sleeve 11 this time,
Density unevenness occurred in the cycle of the developing sleeve.

Therefore, an object of the present invention is to stabilize the formation of a thin toner layer on a developer carrier without causing toner to adhere to the conductive developer regulating member and the developer carrier.
An object of the present invention is to provide a developing device and an image forming apparatus capable of avoiding image defects such as vertical streaks and density unevenness on an image and performing good image formation.

[0013]

The above object is achieved by a developing apparatus and an image forming apparatus according to the present invention. In summary, the first aspect of the present invention is directed to a developer, a rotatable developer carrier for carrying and transporting the developer, and the developer carrier on the developer carrier in contact with the developer carrier. A conductive developer regulating member that regulates a layer thickness of the developer; and a voltage application unit that generates an electric field between the developer carrier and the conductive developer regulating member. A developing device configured to develop the electrostatic latent image formed on the image carrier with the developer conveyed to the body to form a developer image on the image carrier;
The voltage applying means generates an alternating electric field between the rotating developer carrier and the conductive developer regulating member during non-image formation.

According to a second aspect of the present invention, there is provided an image forming apparatus comprising: an image carrier; and a developing device for developing an electrostatic latent image formed on the image carrier with a developer. A developer, a rotatable developer carrier that carries and transports the developer, and a conductive developer that contacts the developer carrier and regulates the layer thickness of the developer on the developer carrier. A developer regulating member, and voltage applying means for generating an electric field between the developer carrier and the conductive developer regulating member, wherein the voltage applying means rotates during the non-image forming period. An image forming apparatus, wherein an alternating electric field is generated between a developer carrier and the conductive developer regulating member.

According to one embodiment of the first and second aspects of the present invention, the apparatus further comprises rotation number detecting means for detecting the rotation number of the developer carrier, and the voltage applying means includes the rotation number detecting means. When the number of rotations of the developer carrying member detected by the controller exceeds a predetermined number, generation of an alternating electric field between the developer carrying member and the conductive developer regulating member is stopped.

According to another embodiment of the first and second aspects of the present invention, the apparatus further comprises humidity detecting means for detecting the humidity of the environment inside or outside the developing device, and the voltage applying means comprises:
When the humidity detected by the humidity detecting means exceeds a predetermined humidity, the generation of the alternating electric field between the developer carrier and the conductive developer regulating member is stopped.

[0017]

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

Embodiment 1 FIG. 2 shows an embodiment of the configuration of the image forming apparatus of the present invention. The image forming apparatus has a photosensitive drum 21 as an image carrier that rotates in the direction of arrow A, and a charging roller 22 that is installed around the photosensitive drum 21 and rotates in the direction of arrow B (followed by the photosensitive drum 21). Then, a charging bias is applied by a power supply device (not shown) to charge the surface of the photosensitive drum 21. The charged surface of the photosensitive drum 21 has an exposure device 23
Forms an electrostatic latent image with light L from
As a result, the electrostatic latent image is developed, and a developer image (toner image) is formed on the photosensitive drum 21.

The thus formed toner image on the surface of the photosensitive drum 21 is transferred to a transfer material 2 by a transfer roller 25 as transfer means.
6 is transferred. The toner remaining on the surface of the photosensitive drum 21 without being transferred to the transfer material 26 is collected by the cleaning device 27, and the surface of the photosensitive drum 21 is cleaned.

Transfer material 26 having a toner image transferred on its surface
Is transported to the fixing device 28, where the toner image on the surface is fixed by the fixing device 28, and is discharged outside the device.

As an image forming apparatus to which the present invention is embodied, there is an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile or the like, or an electrostatic recording apparatus.

Next, the image forming apparatus shown in FIG.
The developing device of the present invention provided as
This will be described with reference to FIG. In this embodiment, a non-magnetic one-component toner is used as a developer.

Developing sleeve 11 as developer carrier
Is rotated in the direction of arrow D (the direction in which the facing portion moves in the same direction as the photosensitive drum 21), facing the photosensitive drum 21. The developing sleeve 11 is in contact with the photosensitive drum 21, but in this case, it may be non-contact. A predetermined developing bias is applied to the developing sleeve 11 by the power supply device 31. The developing sleeve 11 of this embodiment is made of urethane rubber for the base layer and urethane rubber containing silicon particles for the surface layer, and has a roller resistance of 5 × 10 ³ to 5 × 10 ³ .
It is an elastic rubber roller of 2 × 10 ⁷ Ω. The roller resistance in this case is measured by first contacting the developing sleeve with a rotatable cylindrical electrode, connecting the power supply device and the shaft portion of the developing sleeve, and interposing the current measuring device between the cylindrical electrode. The developing sleeve is rotated at 60 rpm while a load of 500 g is applied to one side of the developing sleeve shaft portion, and the developing sleeve shaft portion is connected to the ground by 5 g.
The current value was read by applying 0 V and measured. In this case, as long as the developing sleeve 11 has elasticity, any material may be used, and the resistance is not limited to the above range.

Further, a developing blade 12 as a developer regulating member regulates and charges the toner layer on the developing sleeve 11 to an optimum layer thickness. Is applied. The developing blade 12 of this embodiment was a SUS conductive developer regulating member (straight blade). or,
The developing blade 12 may be any as long as it has conductivity and elasticity.

The toner supply roller 14 is opposed to the developing sleeve 11 in the developing container 16.
It rotates in the direction of arrow E (the direction in which the facing portion moves in the opposite direction to the photosensitive drum 21), which is the direction in which the toner 15 is supplied upward. In this embodiment, the toner supply roller 14 uses a urethane sponge roller. The toner supply roller 14 may be made of any material as long as it has elasticity. The sponge or fur brush structure is effective for supplying toner or peeling off undeveloped toner.

Further, as described in the conventional example, as a method of efficiently providing electric charge to the toner 15, there is a method of externally adding a charge auxiliary to toner base particles. As the charge auxiliary, fine particles having the same polarity as the toner base particles and the same polarity as the toner base particles, and fine particles having the opposite polarity to the toner base particles are used to further charge the fine particles having the same polarity as the toner base particles.

The toner 15 used in this embodiment is a non-magnetic one-component toner, and the toner base particles have negative chargeability and a weight average diameter of 7.1 μm. In this embodiment, the base particles use a spherical toner obtained by a turbid polymerization method.
The production method may be a pulverization method or the like, and may have any shape. 100 parts by weight of the base particles, 1 part of hydrophobic silica fine particles having an average primary particle diameter of 10 nm, and 0.5 part of surface-treated magnesium oxide compound fine particles having an average primary particle diameter of 0.4 μm were added to 100 parts by weight of a base particle using a Henschel mixer Externally added, a toner was obtained.

Here, the order of the triboelectric charging sequence of the hydrophobic silica fine particles and the surface-treated magnesium oxide compound fine particles with respect to the toner base particles is shown in FIG.
It was measured at 00.

FIG. 3 is a schematic diagram of the triboelectric charge amount measuring device 200. The apparatus includes a support table 201 having a portion inclined at 60 ° with respect to the horizontal, and a contact powder storage member 2 provided above the indicating table 201 and configured to store contact powder 202 for measurement.
03, an object support plate 204 supported by the inclined portion of the support 201, and a collection container 205 provided below the support 201 for collecting the contact powder 202 supplied on the object support plate 204. And an electrometer 206 (model 6514 manufactured by KEITHLEY) connected to the object support plate 204, and the contact powder 202 from the contact powder storage member 203 to the object 207 applied on the object support plate 204. And the amount of charge generated by the friction is displayed on the electrometer 206.

The method of evaluating the charging sequence characteristics of the hydrophobic silica fine particles as an external additive to the toner 15 base particles and the surface-treated magnesium oxide compound fine particles in the present invention will be described below. A solution obtained by dissolving the toner base particles in a solvent was dip-coated on the plate 204 as a non-measurement object 207 and dried to obtain a sample.
As the other sample, the hydrophobic silica fine particles and the surface-treated magnesium oxide compound fine particles are separately flowed to the object support plate 204 on the contact powder 202, and the triboelectric charging of the hydrophobic silica fine particles and the surface-treated magnesium oxide compound fine particles with respect to the toner base particles. Row measurements were taken.

As a result, with respect to the toner base particles, the hydrophobic silica fine particles have the same negative polarity as the toner base particles in the charging series, and the surface-treated magnesium oxide compound fine particles have the opposite polarity in the charging series with the toner base particles. It turned out to have positive polarity.

That is, in the toner 15 of the present embodiment, hydrophobic silica fine particles having an average diameter of 10 nm and exhibiting the same negative polarity as the mother particles are added to the base particles having a weight average diameter of 7.1 μm.
Part, average diameter 0.4 μm showing positive polarity opposite to that of base particles
0.5 part of a magnesium oxide compound. Accordingly, the toner 15 used in the present embodiment has the particle diameter described in the conventional example, in the order of toner base particles> fine particles having the opposite polarity to the toner base particles> fine particles having the same polarity as the toner base particles.
It can be seen that the toner is efficiently charged.

Here, the blade bias applied to the developing blade, which is a characteristic part of the developing device of the present invention, will be described. Here, the blade bias means the developing blade potential-the developing sleeve potential.

When no blade bias is applied in the conventional developing device shown in FIG. 11 or the developing device shown in FIG. 1, as shown in Table 1, the phenomenon of toner sticking is caused by low temperature and low humidity (15 ° C.). (° C./10%) in an environment where the toner charge amount is relatively large. It is considered that the cause of the adhesion of the toner is that the toner is attracted to the conductive developing blade by the reflection force.

[0035]

[Table 1]

When the blade bias is not applied, the charge generated by the friction between the toner 15 and the developing blade 12 and the friction between the toner 15 and the developing sleeve 12 are shown in FIGS.
In such a circuit, a current I flows from the blade bias power supply device 32 which is a voltage applying means to the developing blade 12.

Here, among the circuits connected to the developing device 24 of FIG. 1, a circuit having a configuration as shown in FIG. 4 in which a current measuring device 41 is provided between the blade bias power supply 32 and the developing blade 12 is shown. Use in a low-temperature, low-humidity environment (15 ° C / 10
%), The current flowing in the circuit is measured by the current measuring device 41 while changing the blade bias in the state of 3000 prints, and the direction of the current is I flowing from the blade bias power supply 32 to the developing blade 12. A current value profile as shown in FIG. 5 is obtained.

In FIG. 5, when the blade bias is at a predetermined potential A (about -100 V in this embodiment), the amount of electric charge generated by frictional charging is small, and the current value is also small. From this, it is considered that the charge amount of the toner 15 is minimal at the blade bias A.

Here, the charge amount of the toner 15 when the blade bias was actually changed was measured. As a result, the profile of FIG. 6 was obtained. When the blade bias is increased in the same direction as the charging polarity of the toner base particles (in the negative direction in the present embodiment), the current value suddenly increases at a predetermined potential A of the blade bias at which the current value is minimized in FIG. The toner charge amount has decreased. When the blade bias was increased in the same direction as the charge polarity of the toner base particles with the potential A as a critical point, the toner charge amount did not change much. This supported the above considerations.

Thus, it is apparent that the charge amount of the toner 15 can be reduced by increasing the blade bias to a predetermined potential A or more in the same direction as the charge polarity of the toner base particles.

However, it is also added that there is a toner having a small effect of the blade bias. For example, in a system in which only hydrophobic silica fine particles having the same polarity as the toner base particles are externally added,
FIG. 7 shows the current value flowing to the developing blade with respect to the blade bias, and FIG. 8 shows the toner charge amount with respect to the blade bias.

In FIG. 7, there is no predetermined potential such as the predetermined potential A shown in FIG. Therefore, as shown in FIG. 8, even when the blade bias is changed, the toner charge amount is substantially constant (−60 μC
/ G). Further, the same results as those shown in FIGS. 7 and 8 were obtained in the toner to which only the magnesium oxide compound having the opposite polarity to that of the toner base particles and surface-treated was externally added.

As shown in FIG. 6, unless at least one kind of the toner is externally added, at least one of the fine particles having the same charge polarity as the toner base particles and the fine particles having the different charge polarity from the toner base particles. It is apparent that a good profile cannot be obtained and the effect of the blade bias is small.

Therefore, as in this example, one part of hydrophobic silica fine particles having an average diameter of 10 nm and exhibiting a negative polarity having the same polarity as the charge polarity of the base particles was added to the base particles having a weight average diameter of 7.1 μm. In the developing device 24 using the toner 15 containing 0.5 part of a magnesium oxide compound having an average diameter of 0.4 μm and exhibiting a positive polarity opposite to the charging polarity of the base particles, the blade bias A has a low charge amount. Since it is determined as an extreme value, by applying a bias higher than the potential A to the developing blade 12 in the same direction as the charging polarity of the toner 15 as the blade bias, the effect of the blade bias can be stably obtained.

Actually, the developing operation was repeated many times while applying the blade bias A to the toner 15 of this embodiment.

Here, the blade bias (= −200 V) of a potential considered to be higher than the blade bias A is applied to the developing blade 12 by the power supply unit 32 of the developing device in FIG.
And the developing operation was repeated many times. As a result, the toner 15 was not fixed on the developing blade 12, and the image did not have vertical stripes.

However, the toner 15 on the developing blade 12
The toner 15 was fixed on the developing sleeve 11 this time, and the density unevenness of the developing sleeve pitch occurred as an image.

From this result, although the mirroring power was successfully reduced by reducing the charge amount of the toner 15 by the effect of the blade bias, the toner 15 was separated by the effect of the electric field of the blade bias. It was considered that the toner 15 on the developing sleeve 11 was firmly fixed.

As a result of the above considerations, in the present invention,
In order to prevent toner from sticking to both the developing blade 12 and the developing sleeve 11, the power supply device 32 generates an alternating electric field as a blade bias.

When an alternating electric field is applied to the developing blade during the developing operation, the toner coat on the developing sleeve becomes unstable. Therefore, the blade bias is applied except for the developing operation, that is, during non-image formation.

Here, in the following developing devices A, B and C having the configuration of FIG. 1, the developing operation is repeated many times under the environment of the environment temperature of 15 ° C. and the humidity of 10% by changing the manner of applying the blade bias. The state of the vertical streak and image unevenness at the time of the comparison was compared, and the results are shown in Table 2.

The developing device A is a developing device which does not apply a blade bias at all, the developing device B is a developing device which applies a blade bias of -200 V for 5 seconds for every 50 printed sheets, and the developing device C is a developing device of the present invention. In the developing device, a power source device 32 applies a blade bias for generating an alternating electric field of a rectangular wave to the developing sleeve 11 with respect to the developing sleeve at ± 200 V, 10 Hz, and 5 seconds for every 50 printed sheets. is there.

[0053]

[Table 2]

As is clear from Table 2, in the case of using the developing device A to which no blade bias is applied, after printing 2,000 sheets, a vertical streak due to the fusion of the toner of the developing sleeve 12 to the recording paper is generated. In the developing device B with a blade bias of -200 V, no vertical streak was generated, but when the number of sheets exceeded 4000, unevenness in image density due to fusion of the toner on the developing sleeve 11 occurred.

On the other hand, in the developing device C, an alternating electric field is applied to the developing sleeve between the conductive developing blade (made of SUS) which comes into contact with the developing sleeve and regulates the toner and the developing sleeve. 200V, 10H
z, the image was generated while rotating the developing sleeve for one second after the developing operation, thereby making it possible to form an image free of vertical stripes and non-uniformity in the periodic density of the developing sleeve on 10,000 prints.

As described above, at the time of non-image formation, the power supply 3
By applying a blade bias from 2 to generate an alternating electric field between the rotating developing sleeve and the developing blade, vertical streaks on the image due to toner fusion of the developing sleeve,
Further, it is possible to avoid unevenness in density on an image due to toner fusion of the developing blade, and at least one of fine particles having the same charge polarity as toner base particles and at least one of fine particles having different charge polarity from toner base particles These effects were enhanced by using a toner to which one type was externally added.

In the present embodiment, the specification of the blade bias may be 500 V or less in absolute value with respect to the developing sleeve 11, and when the absolute value is 500 V or more, discharge from the developing blade 12 starts. The toner coat becomes unstable. Note that the magnitude of the bias is appropriately adjusted according to the type and setting of the image forming apparatus.

The frequency is not limited to 10 Hz, but may be any Hz. The longer the blade bias application time, the more effective. The timing of performing the blade bias is not limited to after the developing operation, but may be before the developing operation.
The effect can be obtained even when the blade bias is periodically performed after the developing operation is repeated several times.

In this embodiment, the toner having a negative polarity is used as an example. However, when a toner having a positive polarity is used, the polarity of the blade bias of the voltage applying means described in this embodiment is inverted. It is needless to say that the same effect can be obtained if the polarity is reversed or the above-described external additive is used as the external additive of the toner.

Example 2 Although generation of vertical streaks could be suppressed in Example 1, the number of prints was 6000 sheets in a high-temperature and high-humidity (30 ° C./80%) environment as shown in Table 1, or as shown in Table 2. In a situation where the toner charge amount becomes small thereafter, the toner having a small charge amount is scattered without being held on the developing sleeve because the developing blade vibrates minutely under the influence of the alternating electric field.

Therefore, in the present embodiment, the developing operation was performed many times using the developing device having the following two types of mechanisms in addition to the developing device of the first embodiment.

As shown in FIG. 9, the developing device is provided with a counting device 91 which is a rotation speed detecting means for counting the rotation speed of the developing sleeve 11, and the number of prints is 600.
When the number of rotations of the developing sleeve 11 reaches zero, an electric signal is issued from the counting device 91 to stop the generation of the alternating electric field by the power supply device 32.

In this case, the counting device 91 is not limited to the inside of the developing device, but may be provided in the image forming device as long as the number of rotations of the developing sleeve 11 can be monitored. In the present embodiment, the alternating electric field was stopped when the number of prints reached 6000. However, this value must be changed as appropriate according to the properties of the toner 15.
C / g or less.

As another example, as shown in FIG. 10, a humidity sensor 92 as a humidity detecting means is provided in the developing device 26, and when the humidity becomes 50% or more, an electric signal is sent from the humidity sensor 92. There is a method of stopping the generation of the alternating electric field by the power supply device 32.

In this case, the humidity sensor 92 is not limited to the inside of the developing device, but may be provided in an image forming apparatus in which the developing device is incorporated. The means for detecting and measuring the humidity is not limited to the humidity sensor, but may be any method. In this embodiment, the alternating electric field is stopped at a humidity of 50%. However, this value needs to be appropriately changed depending on the properties of the toner 15. In this embodiment, the toner charge amount is set to 40 μC from Table 1.
/ G or less.

As described above, with respect to the developing device of the first embodiment, a mechanism for stopping the alternating electric field when the number of rotations of the developing sleeve exceeds the number of rotations corresponding to 6000 prints,
By adding a mechanism to stop the alternating electric field when the humidity in the developing device exceeds 50%, it is possible to form an image without vertical stripes, uneven development sleeve cycle density, and toner scattering at 10,000 prints. did.

[0067]

As described above, the developing device and the image forming apparatus according to the present invention comprise a rotatable developer carrier for carrying and transporting toner, and a conductive member for contacting the developer carrier and regulating the toner. And a voltage applying means for generating an electric field between the developer carrier and the conductive developer regulating member, and applying a voltage while rotating the developer carrier during non-image formation. Means for generating an alternating electric field between the developer carrying member and the conductive developer regulating member, so that toner is prevented from sticking to the developer carrying member and the developer regulating member, and a vertical image is formed on the formed image. Defects such as streaks and density unevenness could be avoided.

Further, by providing a rotation speed detecting means for detecting the rotation speed of the developer carrier, when the rotation speed of the developer carrier exceeds a certain number, the voltage applying means is electrically connected to the developer carrier. By stopping the generation of an alternating electric field with the developer regulating member and providing humidity detecting means for detecting the humidity of the environment inside or around the developing device, when a certain humidity is exceeded, the voltage applying means Since the generation of the alternating electric field between the developer carrier and the conductive developer regulating member is stopped,
The toner can be prevented from scattering while preventing the toner from sticking to the developer regulating member and the developer carrying member.

In addition, the present invention uses a toner in which at least one kind of fine particles having the same charge polarity as the toner base particles and fine particles having the same charge polarity as the toner base particles is externally added, thereby effectively reducing the blade bias. Work on.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a developing device of the present invention.

FIG. 2 is a schematic configuration diagram showing an embodiment of the image forming apparatus of the present invention.

FIG. 3 is an explanatory diagram illustrating a method of measuring a toner charge amount.

FIG. 4 is a schematic configuration diagram showing a current measuring device for measuring a current by a blade bias and a developing device.

FIG. 5 is a graph showing a relationship between a blade bias and a current flowing through a current measuring device.

FIG. 6 is a graph showing a relationship between a blade bias and a toner charge amount.

FIG. 7 is a graph showing a relationship between a blade bias and a current flowing through a current measuring device.

FIG. 8 is a graph showing a relationship between a blade bias and a toner charge amount.

FIG. 9 is a schematic configuration diagram illustrating a developing device according to another example of the present invention.

FIG. 10 is a schematic configuration diagram illustrating a developing device according to another example of the present invention.

FIG. 11 is a schematic configuration diagram of a conventional developing device.

[Explanation of symbols]

Reference Signs List 11 developing blade (conductive developer regulating member) 12 developing sleeve (developer carrier) 14 toner supply roller 15 toner (developer) 21 photosensitive drum (image carrier) 31 developing bias power supply device 32 blade bias power supply device (voltage Application means) 41 Current measuring device 91 Revolution counting device (Revolution detecting device) 92 Humidity sensor (Humidity detecting device) 200 Friction charging amount measuring device

Continued on front page F-term (reference) 2H005 AA08 DA02 DA03 2H073 AA01 BA03 BA12 BA33 BA43 CA02 2H077 AD06 AD13 AD36 DA18 DA42 DB08 DB14 EA14 GA02 GA03

Claims (8)

[Claims] 1. A developer, a rotatable developer carrier that carries and transports the developer, and a layer thickness of the developer on the developer carrier that is in contact with the developer carrier. A conductive developer regulating member that regulates, a voltage applying unit that generates an electric field between the developer carrier and the conductive developer regulating member,
A developing device that develops an electrostatic latent image formed on the image carrier with the developer conveyed to the developer carrier to form a developer image on the image carrier. The developing device according to claim 1, wherein the voltage applying unit generates an alternating electric field between the rotating developer carrier and the conductive developer regulating member during non-image formation. 2. The image forming apparatus according to claim 1, further comprising: a rotation speed detection unit configured to detect a rotation speed of the developer carrier, wherein the voltage application unit detects a rotation speed of the developer carrier detected by the rotation speed detection unit. 2. The developing device according to claim 1, wherein when a predetermined number is exceeded, generation of an alternating electric field between said developer carrier and said conductive developer regulating member is stopped. 3. The image forming apparatus according to claim 1, further comprising a humidity detecting unit configured to detect a humidity of an environment inside or outside the developing device, wherein the voltage applying unit is configured to detect a humidity when the humidity detected by the humidity detecting unit exceeds a predetermined humidity. 3. The developing device according to claim 1, wherein generation of an alternating electric field between the developer carrier and the conductive developer regulating member is stopped. 4. The developer further comprises at least one kind of fine particles having the same charge polarity as the developer base particles and at least one kind fine particles having a different charge polarity from the developer base particles. 4. The method according to claim 1, wherein
The developing device according to any one of the above items. 5. An image forming apparatus comprising: an image carrier; and a developing device for developing an electrostatic latent image with a developer formed on the image carrier, wherein the developing device comprises: A rotatable developer carrier that carries and transports the developer, and a conductive developer regulating member that contacts the developer carrier and regulates the layer thickness of the developer on the developer carrier, Voltage applying means for generating an electric field between the developer carrying member and the conductive developer regulating member, wherein the voltage applying means rotates during the non-image formation, and An image forming apparatus that generates an alternating electric field between conductive developer regulating members. 6. The image forming apparatus according to claim 1, further comprising: a rotation speed detection unit configured to detect a rotation speed of the developer carrier, wherein the voltage application unit detects a rotation speed of the developer carrier detected by the rotation speed detection unit. 6. The image forming apparatus according to claim 5, wherein when the number exceeds a predetermined number, generation of an alternating electric field between the developer carrier and the conductive developer regulating member is stopped. 7. The image forming apparatus according to claim 1, further comprising a humidity detecting unit configured to detect a humidity of an environment inside or outside the developing device, wherein the voltage applying unit is configured to detect when a humidity detected by the humidity detecting unit exceeds a predetermined humidity. 7. The image forming apparatus according to claim 5, wherein generation of an alternating electric field between the developer carrier and the conductive developer regulating member is stopped. 8. The developer according to claim 5, wherein at least one kind of fine particles having the same charge polarity as the developer base particles and at least one fine particle having a different charge polarity from the developer base particles are externally added to the developer. 8. The image forming apparatus according to any one of items 7 to 7.