JPH07199631A - Developing method and device therefor - Google Patents

Abstract

PURPOSE:To provide a developing device capable of restraining the fluctuation of image density at the time of supplying toner to the minimum. CONSTITUTION:In the respective developing units 22 of a revolver developing device used in a full color printer; a developing current I at the time of developing is detected by the ammeter 11 of a developing bias circuit, and the toner adhesive amount of a solid image on a photoreceptor belt is detected by a reflection type photosensor 10. By controlling a condition for supplying the toner to a developing roller 23 based on the detected results, an appropriate developing condition is obtained. A potential difference, the ratio of rotating linear velocity, and abutting pressure between the developing roller 23 and a supplying roller 31 are used as the toner supplying condition. Instead of the toner supplying condition, it is conceivable to control a condition for supplying external additive such as silica to the toner or a condition for forming a toner thin layer on the developing roller. The abutting pressure and the potential difference between the roller 23 and a developing blade 32 and the projecting amount of the blade 32 are used as the toner thin layer forming condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method for a copying machine, a facsimile, a printer and the like and a developing method and an apparatus for use in the apparatus. More specifically, the present invention supplies a developer to a developer carrier, The present invention relates to a developing method and apparatus for forming a developer layer on a developer carrying member and developing a latent image formed on the image carrying member by the developer layer.

[0002]

2. Description of the Related Art Generally, a developing device using a one-component type developer is compared with a developing device using a two-component type developer.
It is considered to be advantageous from the point that it is not necessary to control the weight ratio of the toner to the developer (toner concentration) and a uniform charge amount can be obtained at all times, and maintainability. However, in reality, the toner itself has a particle size distribution from the viewpoint of productivity and cost by pulverizing the toner of the one-component developer, and there is a distribution of the toner charge amount due to deterioration over time. It is known that the toner is sequentially consumed from a so-called small particle size toner, which is relatively high. (It is considered that this small particle size toner has a strong adhesion to the developer carrying member and easily passes through the pressure contact portion of the developer regulating member.) As a result, at the time of so-called toner end where toner replenishment is required, the toner The average particle size of is quite large. Immediately after replenishing the toner after this toner end, the average particle size of the toner becomes small and the toner passing through the pressure contact portion of the developer regulating member on the developer carrying member has a relatively small particle size. Therefore, the amount of development is reduced as compared with the vicinity of the toner end, and as a result, the image density is significantly reduced. Therefore, the fluctuation of the image density due to the toner supply is repeated.

In order to prevent the fluctuation of the image density, the contact pressure of the developer accumulated in the housing of the developing device is blocked from acting on the back surface of the developer regulating member pressed against the developer carrier. It has been proposed to provide a blocking member and maintain its contact pressure so that the thickness of the developer layer formed on the developer carrying member is substantially constant and an image of uniform density is obtained. (For example, JP-A-5-107897.
(See the official gazette). Also, the floating toner concentration is detected from the optical scattering of the floating toner in the vicinity of the developing device, the toner charge amount is calculated from the detection result, and toner replenishment is controlled based on the calculated toner charge amount. Has been proposed (see, for example, Japanese Patent Laid-Open No. 4-320287).

[0004]

However, in the developing device proposed in JP-A-5-107897 mentioned above,
If the toner particle size or the toner characteristics themselves change, the effect is lost.

Further, in the image forming apparatus proposed in Japanese Patent Laid-Open No. 4-320287, the density of the floating toner is greatly influenced by the particle size as well as the charge amount. Therefore, the calculation accuracy of the charge amount is high. Seems to have a problem with. There is also a problem that the toner actually used for development is not targeted.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a developing device capable of minimizing fluctuations in image density by a simple method.

[0007]

In order to achieve the above object, a developer is supplied to a developer carrying member, a developer layer is formed on the developer carrying member, and an image carrying is carried by the developer layer. A method for developing a latent image formed on a body, comprising:
In the invention, the developing current at the time of development and the amount of the developer adhering to the image carrier are detected, and the condition for supplying the developer to the developer carrier is controlled based on the detection result. According to the invention of claim 2, the developing current at the time of the development and the amount of the developer adhering to the image carrier are detected, and the detection result is obtained. Based on the above, the conditions for replenishing the external additive to the developer are controlled to obtain appropriate developing conditions.
The development current at the time of development and the amount of the developer adhering to the image carrier are detected, and the conditions for forming the developer layer on the developer carrier are controlled on the basis of the detection results to obtain an appropriate value. It is characterized in that development conditions are obtained.

Further, it is provided with a developer carrying member, a developer supplying member for supplying a developer to the developer carrying member, and a developer regulating member for forming a developer layer on the developer carrying member. ,
In a developing device for developing a latent image formed on an image carrier by the developer layer, the invention of claim 4 includes a developing current detecting means for detecting a developing current at the time of the developing, and a developing current detecting means on the image carrier. A developer adhesion amount detecting means for detecting the adhesion amount of the developer,
A developer supply condition control means for controlling the supply condition of the developer by the developer supply member based on the detection result by the development current detection means and the developer adhesion amount detection means. According to a fifth aspect of the present invention, there is provided a developing current detecting means for detecting a developing current at the time of the developing, a developer adhering amount detecting means for detecting an adhering amount of the developer on the image carrier, and the developing current. External additive replenishment condition control means for controlling replenishment conditions for replenishing the external additive to the developer based on the detection result by the detection means and the developer adhesion amount detection means. The invention of claim 6 is
Developing current detecting means for detecting the developing current at the time of developing, developer adhesion amount detecting means for detecting the adhesion amount of the developer on the image carrier, developing current detecting means and developer adhesion amount detecting means And a developer layer forming condition control means for controlling the forming condition of the developer layer based on the detection result of the above.

[0009]

According to the present invention, the developing current at the time of developing the latent image on the image carrier and the amount of the developer adhering to the image carrier are detected. From this detection result, it is possible to know the charge amount and the adhesion amount of the developer on the developer carrier. The amount of charge of the developer has an inverse correlation with the image density, while the amount of the developer attached has a linear relationship with the image density. Further, the charge amount and the adhesion amount of the developer on the developer carrier can be changed by changing the supply condition of the developer to the developer carrier. Therefore, the developer on the developer carrier is detected so that the developing current at the time of development and the amount of the developer deposited on the image carrier are detected and the detection result becomes a predetermined value or falls within a predetermined range. By controlling the supply conditions of, it becomes possible to obtain proper developing conditions.

Further, the charge amount and the adhesion amount of the developer on the developer carrier can be changed by changing the replenishment condition of the external additive to the developer. Therefore, in the invention of claim 2 or 5, the developing current at the time of development and the amount of the developer adhering to the image carrier are detected, and the detection result becomes a predetermined value or falls within a predetermined range. like,
The replenishment condition of the external additive to the developer is controlled. This makes it possible to obtain proper developing conditions.

The charge amount and the adhesion amount of the developer on the developer carrier can be changed by changing the conditions for forming the developer layer on the developer carrier. Therefore, in the invention of claim 3 or 6, the developing current at the time of development and the amount of the developer adhering to the image carrier are detected, and the detection result becomes a predetermined value or falls within a predetermined range. Thus, the conditions for forming the developer layer on the developer carrier are controlled. This makes it possible to obtain proper developing conditions.

[0012]

EXAMPLE An example in which the present invention is applied to a rotary developing device (hereinafter referred to as a revolver developing device) used in a full color printer which is an image forming apparatus will be described below. [Embodiment 1] FIG. 1 shows a revolver developing device 4 according to Embodiment 1.
It is a front view which shows the schematic structure of. Note that FIG. 1 shows a state in which one developing unit, for example, a yellow developing unit is in the developing position. The revolver developing device 4 is arranged in the vicinity of the photosensitive belt 1 rotating as an endless belt in the A direction. Then, in the cover member 41 of the revolver developing device 4, the casing 20 as a rotating body is provided.
Is rotatably provided around a rotation center axis O (not shown), and the casing 20 is rotated in the direction of arrow C by a drive mechanism (not shown). Also, the casing 20
Has an integral shape so as to divide the revolver developing device 4 into four parts, whereby each color developing unit of a yellow developing unit 22Y, a magenta developing unit 22M, a cyan developing unit 22C, and a black developing unit 22K is formed.

The developing units 22Y, 22 of the first embodiment
M, 22C and 22K are developing units using a non-magnetic one-component developer, which are yellow, magenta, cyan, and
And store the black toner. In addition, each developing unit 22
The Y, 22M, 22C and 22K are provided with cylindrical developing rollers 23Y, 23M, 23C and 23K as a developer bearing member, respectively. The developing rollers 23Y, 2
3M, 23C, and 23K are arranged so that a part thereof is exposed to the outside through an opening 22a provided in the casing 20.

Each color developing unit 22Y, 22M, 2
Since the 2C and 22K have the same form and the same operation, the yellow developing unit 22Y will be described as an example in the following description, and the description of the other developing units 22M, 22C and 22K will be omitted. In addition, each developing unit 22Y, 2
Regarding the same corresponding members in 2M, 22C, and 22K, only the letters at the end of the reference numerals in FIG. 1 are changed and shown.

FIG. 2 is a schematic diagram of a developing unit constituting the revolver developing device 4, that is, a yellow developing unit 22Y in this case. In FIG. 2, the developing unit 22Y is arranged below the photosensitive belt 1 when used for development, and supplies yellow toner as a non-magnetic one-component developer to the electrostatic latent image formed on the photosensitive belt 1. .
An opening 22a is formed in the upper part of the casing 20 of the yellow developing unit 22Y at the developing position. A developing roller 23Y is provided in the opening 22a so as to face the photoconductor belt 1 at a predetermined peripheral speed ratio with the photoconductor belt 1 and at a portion facing the photoconductor belt 1 in the moving direction of the photoconductor belt 1. It is arranged to rotate in the same direction as. A shielding member 38Y is provided on a surface portion of the developing roller 23Y on the downstream side in the rotation direction with respect to the portion facing the photosensitive belt 1.
The end portions of the contact portions are in contact with each other to prevent the toner from leaking or scattering from the opening portion 22a.

Below the developing roller 23Y, a supply roller 31Y made of an elastic material such as polyurethane foam is rubbed against the developing roller 23Y as a toner supply member, and
The developing roller 23Y has a predetermined peripheral speed ratio with respect to the developing roller 23Y at the sliding portion 36Y with the developing roller 23Y.
It is provided so as to rotate in the same direction as the rotation direction.

Further, a developing blade 32Y as a developer regulating member made of an elastic material such as urethane rubber is provided on the downstream side in the rotation direction of the developing roller 23Y with respect to the position where the supply roller 31Y is disposed and in the vicinity of the opening 22a. However, the vicinity of its free end is provided so as to contact the developing roller 23Y.

Further, on the left side of the rubbing portion 36Y in the figure, there is provided a screw-shaped first toner carrying member (hereinafter referred to as a first toner carrying screw) 33Y for carrying the toner from the front side to the back side of the paper. Further, below the supply roller 31Y, a screw-shaped second toner conveying member (hereinafter, referred to as a second toner conveying screw) 35Y that conveys toner from the back side of the paper toward the front side is provided. And
At the longitudinal end of the yellow developing unit 22Y, as shown in FIG.
As shown in, a toner storage portion 40Y is provided.
Here, the toner conveying screw 33Y is arranged in parallel with the developing roller 23Y and the supply roller 31Y from the toner containing portion 40Y to the other end portion in the longitudinal direction of the developing unit 22Y, and the toner containing screw 40Y is connected to the yellow developing unit 22Y. In order to convey the toner toward the other end, the toner is rotated in cooperation with the developing roller 23Y and the supply roller 31Y and at a predetermined peripheral speed ratio. Further, the second toner carrying screw 3 is provided in the lower part of the yellow developing unit 22Y.
5Y is arranged in parallel with the developing roller 23Y, the supply roller 31Y, and the first toner carrying screw 33Y, and is rotated so as to carry the toner in the opposite direction to the first toner carrying screw 33Y.

Further, as shown in FIG. 2, the casing 20 is formed so that a part thereof is in contact with the supply roller 31Y, and the developing roller 23Y, the supply roller 31Y and the casing 20 surround the toner conveying member 33Y. The toner transport space 37Y is formed.

Reference numerals 42Y, 42M, 42 in FIG.
C and 42K are the developing units 22Y and 22M,
22C, 22K toner accommodating portions 40Y, 40M, 40
Toner cartridges 42Y, 42M, 42
By mounting and replacing C and 42K at the time of new mounting of the revolver developing device 4 and at the time of toner end, a required amount of toner is always stored in the toner storing units 40Y, 40M, 40C, and 40K. This toner cartridge 42Y, 42
Each of M, 42C, and 42K has a movable valve, and the opening / closing of this movable valve is controlled via a valve drive device (not shown).

A predetermined developing bias voltage is applied to the conductive cored bar of the developing roller 23Y by the developing bias power source 43, and a predetermined toner supply bias power source 44 is applied to the conductive cored bar of the supply roller 31Y. Bias voltage is applied.

In the revolver developing device 4 having the above structure,
The first toner transport screw 33Y transports the toner from the toner container 40 into the toner transport space 37Y by rotating in the predetermined direction and supplies the toner onto the supply roller 31Y. The toner supplied onto the supply roller 31Y is rubbed by the supply roller 31Y and the developing roller 23Y at the rubbing portion 36Y and is charged while being developed.
It is supplied to the surface of Y and is carried on the surface of the developing roller 23Y. The toner carried on the surface of the developing roller 23Y is made into a toner thin layer having a uniform thickness and a predetermined thickness by the developing blade 32Y, and the electrostatic latent image formed on the surface of the photosensitive belt 1 is contacted or non-contact developed. develop.

The toner that has not been used in the developing step is conveyed by the first toner conveying screw 33Y to the end of the developing unit opposite to the toner containing portion 40Y. First
The toner carried by the toner carrying screw 33Y to the toner circulating portion 34Y falls under the yellow developing unit 22Y due to gravity. Then, the toner dropped to the lower part in the yellow developing unit 22Y is transferred to the first toner transfer screw 33 by the second toner transfer screw 35Y.
By being transported in the direction opposite to Y, the toner not used in the developing process is transported to the toner storage unit 40Y.

The revolver developing device 4 having the above-described structure synchronizes with the color information and develops units 22Y, 22M, 22.
The developing unit 22Y, 2K is rotated about the rotation center axis O so as to selectively dispose C, 22K at the developing position.
The 2M, 22C, and 22K rotate the developing rollers 23Y, 23M, 23C, and 23K in the direction of arrow D in the drawing at the developing position to sequentially develop the corresponding electrostatic latent images formed on the photosensitive belt 1. Then, the developed images are superimposed on the intermediate transfer belt (not shown) and the transfer paper to form a full-color image.

By the way, immediately after the toner is replenished at the toner end in the developing process by the developing unit 22Y, the amount of development is reduced as compared with immediately before the toner end, and as a result, the image density is remarkably lowered. Therefore, FIG.
As shown by the solid line, the fluctuation of the image density due to the toner supply is repeated. The horizontal axis in FIG. 4 is time, and the arrows of symbols S ₁ , S ₂ , and S ₃ respectively indicate the toner supply timing.

Here, as shown in FIG. 5, the image density ID
And a toner adhesion amount m / a on the developing roller have a linear relationship. On the other hand, the toner adhesion amount m / a on the developing roller
Between the toner charge amount q / m and the toner charge amount q / m basically have an inverse correlation as shown in the measured data of FIG. 6, and when the toner charge amount q / m is high, the toner adhesion amount m / a becomes low. Therefore, in order to increase the image density, it is necessary to increase the toner adhesion amount m / a, and for that purpose, it is sufficient to decrease the toner charge amount q / m. (Hereafter, margin)

Further, FIGS. 7A, 7B and 7C show
The time change of the instantaneous value dm / dt of the toner adhesion amount of the solid image formed on the photosensitive belt 1 before and after the toner replenishment, the developing current I, and the instantaneous value dq / dm of the toner charge amount are respectively modeled. It is shown in. The horizontal axis in the figure is time, and its numerical value corresponds to the rotation speed of the developing roller 23Y. As can be seen from FIG. 7A, the instantaneous value dm / dt of the toner adhesion amount of the solid image on the photosensitive belt 1 is constant at the developing roller 2 to 3 rotations, but tends to decrease at 3 rotations or more. Show. Moreover, the difference before and after the toner replenishment was clearly recognized. Also in the graph of the developing current I in FIG. 7B, the same tendency as in FIG. 7A and the difference before and after the toner replenishment are recognized. Here, using the data shown in FIGS. 7A and 7B,

As shown in Equation 1, the instantaneous value dq / dm of the toner charge amount q / m at a certain time can be obtained. Figure 7
In (c), the time change of the instantaneous value dq / dm of the toner charge amount is shown. From these graphs, the toner charge amount q / m of the latter is clearly higher immediately before and immediately after toner replenishment. At this time, the toner adhesion amount m / a is low.

[0028]

## EQU1 ## I / (dm / dt) = (dq / dt) / (dm
/ Dt) = dq / dm

Therefore, in the first embodiment, the photosensitive belt 1
A predetermined image density is obtained by detecting the toner adhesion amount and the developing current of the solid image above and controlling the toner supply condition to the developing roller based on the detection result. In the revolver developing device 4, as a developer adhesion amount detection means for detecting the adhesion amount of toner in a continuous solid image (having a certain width) formed by keeping the surface potential of the photoconductor belt 1 constant. As shown in FIGS. 1 and 2, the reflective photosensor 10 is arranged at the opening end of the cover member 41. Further, as a developing current detecting means for detecting the developing current, the ammeter 11 is connected in series with the developing bias power source 43 between the conductive core metal of the developing roller 23Y and the ground.

The toner supply condition, which is a control parameter for changing the toner charge amount q / m and the toner adhesion amount m / a on the developing roller, is the developing roller 2
The potential difference between 3Y and the supply roller 31Y, the contact pressure between both rollers, and the relative rotational linear velocity ratio between both rollers can be used. For example, as shown in FIGS. 8 and 9, by changing these toner supply conditions, the toner charge amount q /
m and the toner adhesion amount m / a on the developing roller can be changed. In the figure, ΔVsp on the horizontal axis is the developing roller 2.
3Y is the potential difference (Vb-Vs) between the supply roller 31Y, the value of the parameter t in the figure is the thickness of the spacer for adjusting the contact pressure of the developing blade 32Y, and the value on the right side thereof (0 .9, 1.2) is the relative rotational linear velocity ratio (vs / vd) of the supply roller / developing roller. The error bars in the figure represent the range of standard deviation ± σ of the measurement data. Further, the priority order of control in the first embodiment is set in the order of potential difference, relative rotational linear velocity ratio, and contact pressure. Also,
As the developer supply condition control means, for example, CPU, R
A control electrical unit (not shown) of the main body of the apparatus, which is composed of an AM, ROM, I / O interface, etc., can be used.

In the control of the revolver developing device 4 having the above structure, when the potential difference ΔVsp between the developing roller 23Y and the supply roller 31Y is increased, the toner charge amount q / m on the developing roller 23Y in FIG. 6 decreases. At the same time
Since the toner adhesion amount m / a on the developing roller 23Y increases, the developing current I and the toner adhesion amount on the photosensitive belt 1 are detected by the reflective photosensor 10 and the ammeter 11 while changing the potential difference ΔVsp. From the detection result, it is confirmed whether the toner charge amount q / m and the toner adhesion amount m / a have changed to required values. If the required value is not reached, the potential difference ΔVsp is further increased and the toner charge amount q / m and the toner adhesion amount m / a are repeatedly controlled so as to reach the final target values.

If the target value is not reached even if the potential difference ΔVsp is maximally changed, control is performed to change the relative rotational linear velocity ratio (vs / vd) of the supply roller / developing roller, which is the next priority. To do. Further, when the target value is not reached, the contact pressure between both rollers is controlled to be changed. The above three types of control parameters may be appropriately combined and controlled simultaneously.

As described above, according to the first embodiment, the developing current I and the toner adhesion amount on the photosensitive belt 1 are detected, and the toner charge amount q on the developing roller 23Y is detected based on the detection results.
/ M and the toner adhesion amount m / a, the toner supply to the developing roller such as the potential difference between the developing roller 23Y and the supply roller 31Y, the contact pressure of both rollers, and the relative rotational linear velocity ratio of both rollers. By controlling the conditions, it is possible to obtain appropriate developing conditions, and as shown by the alternate long and short dash line in FIG. 4, the fluctuation of the image density during toner replenishment is remarkably improved as compared with the conventional example.

In the first embodiment, if the output of a counter or the like is appropriately used to control the toner supply condition at regular intervals (for example, about every 100 prints), it is possible to change the time. The increase in image density can be suppressed.

Example 2 By the way, in the revolver developing device 4 shown in FIG. 1, silica (a compound of SiO ₂ ) and titanium compound (TiO ₂ ) having a diameter of 10 to 30 nm (cf. the diameter of the toner is 7 to 11 μm). ) And other additives (external additives)
However, it is externally added to the toner and mixed with the toner particles mainly for the purpose of improving the releasability, preventing the toner aggregation and improving the transferability of the toner image. However, especially near the toner end, the external additive is buried in the toner, and its function is not fulfilled. Further, this external additive is the toner charge amount q
/ M, the toner charge amount q / m also decreases in the so-called buried state. When the toners agglomerate to reduce the toner charge amount q / m and the toner adhesion amount m / a on the developing roller increases, the image density increases.

Therefore, in the second embodiment, in the revolver developing device 4 similar to the first embodiment, instead of controlling the toner supply condition to the developing roller, the developing current I and the toner adhesion amount on the photosensitive belt 1 are replaced. The external additive replenishment condition is controlled while checking the toner charge amount q / m and the toner adhesion amount m / a on the developing roller 23Y based on the detection result. However, excessive addition of external additives affects development and other factors.Therefore, based on the toner remaining amount calculated from the number of prints from the time of toner supply to the developing device, After determining the upper limit,
Replenish external additives. For example, the remaining toner amount is 30 g,
If the specified concentration of the external additive is 0.7 (wt%) and 20% of the additive is effective in the state of residual toner, 30
(G) x 0.7 (wt%) x 80 (%) = 16.8 (m
It is considered that the addition amount of g) is the upper limit.

The external additive thus replenished is intermittently supplied, and when it passes between the developing blade 32Y and the developing roller 23Y, the external additive is externally added to the toner particles, so that it is similar to the initial toner. The characteristics are maintained.
Originally, it is preferable to adhere to the toner particles, but it is considered that the effect as an external additive can be obtained by being present in at least the developer.

In order to replenish the additive as described above, in the second embodiment, as shown in FIG. 2, the silica bar 12 in which silica is mechanically hardened is arranged at a position where it can be appropriately brought into contact with the supply roller 31Y. I have set up. Then, the silica bar 12 is rubbed with the toner supply 31Y, so that the silica bar 12 is rubbed.
Are abraded and silica particles are scraped off. Here, the contact of the silica bar 12 with the supply roller 31Y is performed by a silica bar driving device (not shown), and is configured to interlock with a counter for the number of printed sheets. For example, if the number of prints is 1500 and 16.8 mg, 0.01
It should not exceed 68 mg.

If the external additive cannot be solidified by itself, it may be solidified by further adding a binder agent of a material that does not affect the charging. Further, the silica bar 12 may be arranged so as to come into contact with another member.

In the control of the revolver developing device 4 having the above-described structure, when the replenishment amount of silica particles is increased, the toner charge amount q / m on the developing roller 23Y in FIG. 6 is increased, and at the same time, on the developing roller 23Y. Toner adhesion amount m /
Since a decreases, the developing photocurrent I and the toner adhesion amount on the photosensitive belt 1 are detected by the reflective photosensor 10 and the ammeter 11 while changing the supply amount of silica particles.
From the detection result, it is confirmed whether the toner charge amount q / m and the toner adhesion amount m / a have changed to required values. If the required value has not been reached, the replenishment amount of the silica particles is further increased and the toner charge amount q / m and the toner adhesion amount m / a are repeatedly controlled so as to reach the final target values.

As described above, according to the second embodiment, the developing current I and the toner adhesion amount on the photosensitive belt 1 are detected, and the toner charge amount q on the developing roller 23Y is detected based on the detection result.
By controlling the replenishment condition of the external additive such as silica while checking / m and the toner adhesion amount m / a, an appropriate developing condition can be obtained as in the first embodiment.

[Third Embodiment] In the revolver developing device 4 similar to the first embodiment, instead of controlling the toner supply condition to the developing roller, the developing current I and the photosensitive belt 1 are replaced.
Detects the toner adhesion amount on the top, and based on the detection result,
The toner thin layer forming condition on the developing roller 23Y may be controlled while confirming the toner charge amount q / m and the toner adhesion amount m / a on the developing roller 23Y. The toner thin layer forming condition is that the developing blade 32Y and the developing roller 23Y.
And the contact pressure, the potential difference, and the amount of protrusion of the developing blade 32Y with respect to the developing roller 23Y. In particular, since the contact pressure and the potential difference affect the toner charging characteristics as shown in the examples of FIGS. 8 and 9, the toner charging characteristics can be greatly changed. Example 3
Then, the order of control of the toner thin layer forming conditions is set to the order of contact pressure → potential difference → protrusion amount of the developing blade 32Y with respect to the developing roller 23Y.

As described above, according to the third embodiment, the developing current I and the toner adhesion amount on the photosensitive belt 1 are detected, and the toner charge amount q on the developing roller 23Y is detected based on the detection result.
/ M and the toner adhesion amount m / a are controlled, the toner thin layer forming conditions are controlled, so that an appropriate developing condition can be obtained as in the first embodiment.

In each of the above embodiments, the case where the above control is applied to the yellow toner developing unit 22Y has been described, but the other developing units 22M, 22C,
The same can be applied to 22K, and similar effects can be obtained.

The control in each of the above embodiments may be carried out independently, or may be carried out by appropriately combining the respective controls.

Although the above embodiments have been described with respect to the case of the revolver developing device used in the full-color printer having the four developing units 22, the present invention is also applied to the developing device used in a normal monochromatic copying machine or the like. The same effect can be obtained.

[0047]

According to the invention of claim 1 or 4, the developing current at the time of development and the amount of the developer adhering to the image carrier are detected so that the detection result becomes a predetermined value or a predetermined value. By controlling the supply condition of the developer to the developer carrying member so that it falls within the range, the proper developing condition can be obtained, so that the fluctuation of the image density can be minimized even when the developer is replenished. The effect is that you can.

According to the invention of claim 2 or 5, the developing current at the time of development and the amount of the developer adhering to the image carrier are detected so that the detection result becomes a predetermined value or within a predetermined range. By controlling the replenishment condition of the external additive to the developer so that the proper development condition can be obtained,
There is an effect that the fluctuation of the image density can be minimized even when the developer is replenished.

According to the invention of claim 3 or 6, the developing current at the time of development and the amount of the developer adhering to the image carrier are detected so that the detection result becomes a predetermined value or within a predetermined range. By controlling the conditions for forming the developer layer on the developer carrier so that proper development conditions can be obtained, the fluctuation of the image density can be minimized even when the developer is replenished. The effect is that you can.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a revolver developing device according to an embodiment.

FIG. 2 is a schematic configuration diagram of a developing unit 22Y of the revolver developing device.

FIG. 3 is a perspective view of the revolver developing device.

FIG. 4 is a characteristic diagram showing a change in image density when toner is replenished.

FIG. 5 is a characteristic diagram showing a relationship between toner adhesion amount m / a on a developing roller and image density.

FIG. 6 is a characteristic diagram showing a relationship between a toner adhesion amount m / a on a developing roller and a toner charge amount q / m.

FIGS. 7A, 7B, and 7C are characteristic diagrams showing changes over time in the toner adhesion amount, the developing current, and the toner charge amount on the photosensitive belt, respectively.

FIG. 8 is a potential difference ΔVsp between a developing roller and a supply roller.
And a toner charge amount q / m.

FIG. 9 is a potential difference ΔVsp between a developing roller and a supply roller.
And a characteristic diagram showing the relationship between the toner adhesion amount m / a and the image density.

[Explanation of symbols]

 1 Photoconductor Belt 4 Revolver Developing Device 10 Reflective Photo Sensor 11 Ammeter 12 Silica Bar 22 Developing Unit 23 Developing Roller 31 Supplying Roller 32 Developing Blade 43 Developing Biasing Power Supply 44 Toner Supplying Biasing Power Supply

Claims (6)

[Claims] 1. A developing method in which a developer is supplied to a developer carrier, a developer layer is formed on the developer carrier, and a latent image formed on the image carrier by the developer layer is developed. In the above, the developing current at the time of development and the amount of the developer adhering to the image carrier are detected, and based on the detection result, the condition for supplying the developer to the developer carrier is controlled, and Developing method which obtains various developing conditions. 2. A developing method in which a developer is supplied to a developer carrier, a developer layer is formed on the developer carrier, and a latent image formed on the image carrier is developed by the developer layer. In the above, the developing current at the time of development and the amount of the developer adhering to the image bearing member are detected, and the replenishment condition of the external additive to the developer is controlled on the basis of the detection result to obtain an appropriate value. A development method characterized by obtaining development conditions. 3. A developing method in which a developer is supplied to a developer carrier, a developer layer is formed on the developer carrier, and the latent image formed on the image carrier by the developer layer is developed. In the above, the developing current at the time of development and the amount of the developer adhering to the image carrier are detected, and the conditions for forming the developer layer on the developer carrier are controlled based on the detection results, A developing method characterized by obtaining proper developing conditions. 4. A developer carrying member, a developer supplying member for supplying a developer to the developer carrying member, and a developer regulating member for forming a developer layer on the developer carrying member. In a developing device for developing a latent image formed on an image carrier by the developer layer, a developing current detecting means for detecting a developing current at the time of development, and an amount of the developer attached on the image carrier are A developer adhesion amount detection means for detecting, and a developer supply condition control means for controlling the supply condition of the developer by the developer supply member based on the detection results by the development current detection means and the developer adhesion amount detection means. And a developing device. 5. A developer carrying member, a developer supplying member for supplying a developer to the developer carrying member, and a developer regulating member for forming a developer layer on the developer carrying member. In a developing device for developing a latent image formed on an image carrier by the developer layer, a developing current detecting means for detecting a developing current at the time of development, and an amount of the developer attached on the image carrier are A developer adhering amount detecting means for detecting, and an external additive replenishing for controlling a replenishing condition for replenishing the external additive to the developer based on the detection results by the developing current detecting means and the developer adhering amount detecting means. A developing device provided with a condition control means. 6. A developer carrying member, a developer supplying member for supplying a developer to the developer carrying member, and a developer regulating member for forming a developer layer on the developer carrying member. In a developing device for developing a latent image formed on an image carrier by the developer layer, a developing current detecting means for detecting a developing current at the time of development, and an amount of the developer attached on the image carrier are A developer adhesion amount detecting means for detecting, and a developer layer forming condition control means for controlling the formation condition of the developer layer based on the detection results by the developing current detecting means and the developer adhesion amount detecting means are provided. A developing device characterized in that