JP2000029297A - Developing device and image forming device provided with same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of replenishing toner to a developer container inside by correctly detecting the toner in the developer inside the developer container and an image forming device provided with the same. SOLUTION: A two component developer 43 comprises, non magnetic toner with the toner of a particle in a spherical shape and a magnetic carrier in which, when assuming the absolute maximum length of the carrier particle as L, the maximum projection area as A, and the maximum peripheral length as P, globular factor SF1 expressed by, SF1=(L2/A)×(π/4)×100 is >=100 to <=140, globular factor SF2 expressed by, SF2=(P2/A)×(π/4)×100 is >=100 to <=120, and specific resistance is >=1×1010Ω.cm to <=1×104 Ω.cm. A CPU 67 is, in accordance with the image information from the original 81, made possible to correct the toner quantity fed from a toner replenishing tank 60 to a developer container 44a in accordance with the detection result of a toner density detecting sensor 80.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic or electrostatic recording system for making a latent image formed on a latent image carrier with a developer and visualizing the latent image. The present invention relates to an image forming apparatus, and more particularly, to a developing apparatus for appropriately controlling the toner concentration of a two-component developer and an image forming apparatus including the developing apparatus.

[0002]

2. Description of the Related Art In general, a two-component developer mainly composed of toner particles and carrier particles is used in a developing device provided in an electrophotographic or electrostatic recording type image forming apparatus. In particular, in a color image forming apparatus that forms a full-color or multi-color image by an electrophotographic method, most developing devices use a two-component developer from the viewpoint of the tint of the image.

As is well known, the toner concentration of this two-component developer (ie, the ratio of the weight of toner particles to the total weight of carrier particles and toner particles) is a very important factor in stabilizing image quality. ing.

[0004] Toner density changes as toner particles of a developer are consumed during development. Therefore, there is a need for a developing device that can accurately detect the toner concentration of the developer in a timely manner, replenish the toner according to the change, constantly control the toner concentration, and maintain the image quality.

FIG. 1 shows a schematic configuration of an electrophotographic digital copying machine as an example of an image forming apparatus having a conventional developing device.
0 will be described.

In such an image forming apparatus, first, an image of a document 31 is read by a CCD 1, and an obtained analog image signal is amplified to a predetermined level by an amplifier 2 and is converted to an analog-digital converter (A / D converter). Device 3 converts the digital image signal into a digital image signal of, for example, 8 bits (0 to 255 gradations).

Next, the digital image signal is supplied to a gamma converter (a converter composed of a 256-byte RAM in this example, which performs density conversion by a look-up table method) 5 and is corrected. Analog converter (A / D
(Converter) 9. Here, the digital image signal is
The signal is again converted into an analog image signal and supplied to one input of the comparator 11.

The other input of the comparator 11 is supplied with a triangular wave signal of a predetermined period generated from the triangular wave generating circuit 10. The analog image signal supplied to one input of the comparator 11 is compared with the triangular wave signal. And pulse width modulated.

The above-mentioned pulse width-modulated binary image signal is input to the laser drive circuit 12 as it is, and is used as an on / off control signal for emission of the laser diode 13. A laser beam emitted from a laser diode 13 is scanned in a main scanning direction by a well-known polygon mirror 14, and is rotated through an f / θ lens 15 and a reflection mirror 16 in a direction indicated by an arrow. Irradiated on the surface 17 to form an electrostatic latent image.

On the other hand, the photosensitive drum 17 is uniformly discharged by the exposing device 18 and is uniformly charged, for example, negatively by the primary charging device 19, and then is irradiated with the laser light to generate static electricity corresponding to the image signal. An electrostatic latent image is formed. The electrostatic latent image is developed into a visible image (toner image) by a developing device 20 as a developing device. The toner image has two rollers 2
The image is transferred to the transfer material 23 held on a transfer material carrying belt 27 that is stretched between the transfer rollers 5 and 26 and driven endlessly in the direction of arrow b by the action of the transfer charger 22.

The residual toner remaining on the photosensitive drum 17 is then scraped off by a cleaner 24. Note that only a single image forming station (including a photosensitive drum 17, an exposing unit 18, a primary charger 19, a developing unit 20 and the like) is shown for simplicity of description, but in the case of a color image forming apparatus. For example, the image forming stations for the respective colors of cyan, magenta, yellow, and black are sequentially arranged on the transfer material carrying belt 27 along the moving direction.

Further, in order to correct the changed toner density in the developing device 20 due to the development of the latent image, a video count type developer density control is performed, and the output level of the digital image signal for each pixel is controlled. And the toner is predicted and replenished. That is, the output level of the image signal converted into the digital signal by the analog-digital converter 3 is integrated for each pixel, the video signal is converted into a video count number by the video counter 4 and sent to the CPU 6. The number is converted into a toner replenishment amount and sent to the motor drive circuit 7 as a toner replenishment signal.

The motor drive circuit 7 drives the motor 28 for a time corresponding to the toner replenishment signal, and rotates and drives the toner conveying screw 30 in the toner replenishment tank 8 containing the toner 29 for the above-mentioned predetermined time. 8, an appropriate amount of toner is supplied into the developing device 20 so that the toner density in the developing device 20 is kept constant.

However, the conventional developing device does not directly detect the toner density of the developer 21, but converts the density information of the original image into a video count number, converts this into a replenishment amount, and estimates the consumption amount. The toner supply from the toner supply tank 8 to the developer container 20a, the consumption amount (the toner supply amount from the toner supply tank 8 to the developer container 20a). When the consumption amount of toner (toner consumption) fluctuates, it is not possible to cope with the fluctuation, and due to these fluctuations, the toner concentration, that is, the mixing ratio between the toner particles and the carrier particles gradually deviates from the initial set value (specified value). Come. For this reason, in the conventional developing device, there is a possibility that the toner density is largely deviated from the allowable range of the initial set value.

Various methods other than the video count method have been conventionally proposed for detecting the mixing ratio between the toner particles in the developer container 20 and the magnetic carrier. For example, light is applied to toner provided around the photosensitive drum 17 and displaced from the developing device 20 side to the photosensitive drum 17 side, and the ratio of the toner in the developer (hereinafter referred to as T / D ratio) and the developing device 20
A method of detecting a T / D ratio from reflected light when light is applied to the developer applied on the developing sleeve 20b.
A change in the apparent magnetic permeability μ is detected from the ratio of the carrier contained in the developer in a certain volume near the sensor using the inductance of the coil provided in the developer container 20, and T /
A method of detecting the D ratio has been proposed and put into practical use.

Light is applied to the toner provided around the photosensitive drum 17 and displaced from the developing sleeve 20b to the photosensitive drum 17, and the T / D ratio is detected from the transmitted light and reflected light. And the type of the developer 21 provided on the developing sleeve 20b and applied to the developing sleeve 20b.
With respect to a method of detecting a T / D ratio from reflected light when light is applied to a device, there has been proposed a method in which the accuracy of toner density control is improved by using the method in combination with the video count method.

[0017]

However, the detection means of the type which detects the T / D ratio from the amount of the developing toner on the photosensitive drum 17 has been developed in accordance with the miniaturization of the developing device or the image forming apparatus. However, even if the space can be secured, there is a problem that stable detection cannot be performed due to charging, change of a latent image, or mechanical tolerance (for example, a distance between a developing sleeve and a photosensitive drum). ,
The detecting means of the type that detects the T / D ratio from the reflected light when the developer 21 applied on the developing sleeve 20b is irradiated with light, accurately detects the T / D ratio when the detecting means is contaminated by toner scattering or the like. The / D ratio may not be detected.

On the other hand, a detecting means of a system for detecting the T / D ratio by detecting the change in the apparent magnetic permeability μ of the carrier contained in the developer 21 in a fixed volume near the sensor using the inductance of the coil. In the following, the sensor for detecting the toner concentration is not only inexpensive, but also free from the above-mentioned space problems and the problem of contamination caused by toner scattering. Since the toner concentration of the developer in the container can be detected,
It can be said that this is an optimum T / D ratio detecting means in a low-cost, small-space developing device or image forming device.

However, the above-described toner density detection sensor of the type that detects the change in the apparent magnetic permeability μ of the developer in a certain volume, when the bulk density of the developer itself changes due to some influence, Since the apparent magnetic permeability of the developer 21 changes with the change in the bulk density, the sensor output may change in accordance with the change in the magnetic permeability.

A toner density detection sensor utilizing a change in magnetic permeability indicates that, for example, when the magnetic permeability increases, the T / D in the developer decreases within a certain volume. The toner supply is started because it means that the toner amount has decreased. Conversely, when the magnetic permeability decreases, it means that the T / D ratio in the developer has increased within a certain volume. T / D based on a sequence in which toner supply is stopped to indicate that the amount of toner inside has increased
Control the ratio.

Therefore, if the bulk density changes in the developer container while the T / D ratio in the developer container 20 is constant, the amount of developer (carrier) in a certain volume near the toner concentration detection sensor changes. Therefore, the change in the magnetic permeability at that time appears in the sensor output.

As a result, a sensor output indicating that the amount of toner has decreased is output without consuming toner, and toner is replenished, or the amount of toner decreases despite the amount of toner decreasing. There is a problem that a sensor output is output that does not occur and toner is not supplied. In the former case, there is a problem that the image density is increased due to excessive toner supply, a problem that the developer amount increases with an increase in the toner amount and the developer overflows from the developer container, or an increase in the toner ratio in the developer. May cause problems such as toner scattering due to a decrease in the toner charge amount. On the other hand, in the latter case, problems such as image degradation due to a decrease in the amount of toner in the developer, a low image density due to an increase in the toner charge amount, and the like. May be caused.

The cause of the above-mentioned problem is that the developer used in the above-described developing method is caused by a change in the shape of a conventionally commonly used pulverized toner as a result of a detailed study by the present inventors. The toner has irregularities in the shape of each toner and is different from each other. Therefore, in a stationary state, a flowing state, and a standing state, the bulk density of the developer is easily changed, and the change in the toner shape due to the endurance causes a large change in the bulk density. I understand.

For this reason, in the case of the conventionally used pulverized toner, the bulk density of the developer tends to fluctuate. Therefore, the apparent magnetic permeability μ change of the developer in a certain volume near the sensor is utilized by utilizing the inductance of the coil. And T
It can be said that it is difficult to use the density detection sensor that detects the / D ratio.

Further, in the forward rotation of the developing sleeve 20b in the conventional example, the developer is clogged in the agent reservoir near the regulating blade above the developing sleeve 20b, causing the developing sleeve 20b to rotate.
b, the developer is easily compressed in the agent pool, the frictional force between the agents due to the rotation of the developing sleeve 20b increases, and the further the developing sleeve 20b rotates, the more the toner is charged. As a result, the amount of toner charge from the initial toner charge becomes large. A large variation in the toner charge amount indicates a large variation in the repulsive force between the developers. The repulsive force between the developers tends to repel as the charge amount of the toner increases, and the repulsion spreads between the developers, so that the bulk density of the developer may decrease.

Accordingly, the present invention provides a developing device capable of accurately detecting the amount of toner in a developer in a developer container and supplying toner to the developer container, and an image forming apparatus having the developing device. For the purpose of providing.

[0027]

According to the present application, the object is to provide a two-component developer containing a toner and a carrier on a developer carrier, and a latent image carrier formed in accordance with image information. A developer device for visualizing the electrostatic latent image by applying the toner to the electrostatic latent image on the body, the developer device containing a two-component developer, and a toner container for replenishing the developer container with toner. A toner supply means, and a control means for controlling the amount of toner supplied to the developer container by the toner supply means in accordance with the image information, by detecting the magnetic permeability in the developer container. It has a detecting means for detecting the amount of toner in the container, the two-component developer is a non-magnetic toner in which the toner is spherical particles, and the carrier has an absolute maximum length of carrier particles L and a maximum projected area A. Maximum circumference is P To ^{_{come, SF 1 = (L 2 /}} A) × (π /
4) The spherical coefficient SF ₁ represented by × 100 is 100 or more and 140 or less, SF ₂ = (P ² / A) × (π / 4) × 100
120 following in represented by spherical coefficient SF ₂ is 100 or more,
And 1 × 10 ¹⁴ Ω when the specific resistance is 1 × 10 ¹⁰ Ω · cm or more
The first is that the magnetic carrier is not more than cm, and the control means is capable of correcting the amount of toner supplied to the developer container in accordance with the image information by the toner supply means in accordance with the detection result of the detection means. This is achieved by the invention.

According to the present application, the above object is achieved in the first aspect by the control means, wherein the control means is configured to detect the toner amount detected by the detection means, a predetermined reference toner amount, or the detection amount previously detected by the detection means. The invention is also achieved by the second invention in which the toner supply means can adjust the amount of toner supplied to the developer container in accordance with the difference from the amount of toner.

Further, according to the present invention, the above object is achieved in the first invention or the second invention, in which the control means converts the image information into a toner supply time or a toner supply amount of the toner supply means. And a second table for converting the amount of toner detected by the detecting unit into a toner supply time or a toner supply amount of the toner supply unit, and a third table indicating a relationship between the first table and the second table. Is also achieved by

According to the present application, the above object is achieved by any one of the first to third inventions, wherein the detecting means comprises:
The invention is also achieved by the fourth invention in which the developer is disposed at a position where the flow velocity of the developer is constant and the flow is regular, and the toner concentration in the developer container can be detected when the developing device is driven.

Further, according to the present application, the above object is achieved in any one of the first to fourth inventions, wherein the nonmagnetic toner has a spherical coefficient SF ₁ of 100 or more and 140 or less, _This is also achieved by the fifth invention in which ₂ is not less than 100 and not more than 120.

Further, according to the present application, the above object is achieved in any one of the first to fifth inventions, wherein the developer carrier is provided at a portion where the latent image carrier and the developer carrier are opposed to each other. The present invention is also achieved by the sixth invention in which a regulating member which rotates so as to move in directions opposite to each other and regulates the amount of the developer on the developer carrier below the developer carrier is provided.

Further, according to the present application, the above object is achieved according to any one of the first to sixth inventions, wherein the magnetic carrier comprises a binder resin, a magnetic metal oxide, and a non-magnetic metal oxide. The present invention is also achieved by the seventh invention in which the contained resin magnetic carrier is a high-resistance carrier produced by a polymerization method.

According to the present application, an object of the present invention is to provide an image forming apparatus for recording an image formed by a series of image forming processes on a recording medium, comprising the developing device of the first invention. The invention is also achieved by the invention of (1).

Further, according to the present application, the above object is achieved according to the eighth aspect, in which the control means determines the difference between the detected toner amount of the detection means and a preset reference toner amount or a previously detected toner amount. Accordingly, the invention is also achieved by the ninth invention in which the toner supply means can adjust the amount of toner supplied to the developer container.

According to the present application, the above object is achieved in the eighth or ninth aspect of the present invention in which the control means converts the image information into a toner supply time or a toner supply amount of the toner supply means. A tenth invention having a second table for converting the amount of toner detected by the detecting means into a toner replenishing time or a toner replenishing amount of the toner supplying means, and a third table showing a relationship between the first table and the second table. Is also achieved by

Further, according to the present application, the above object is achieved according to any one of the eighth to tenth aspects, wherein the detecting means is arranged at a position where the flow velocity of the developer is constant and the flow is regular. The present invention is also achieved by the eleventh invention in which the toner concentration in the developer container can be detected when the developing device is driven.

According to the present application, the above object is achieved by any one of the eighth to eleventh aspects of the present invention, wherein the nonmagnetic toner has a spherical coefficient SF ₁ of 100 or more and 140 or less, SF ₂ is also achieved by a twelfth invention of is 120 or less 100 or more.

Further, according to the present application, the above object is achieved in any one of the eighth to twelfth inventions in that the developer carrier is provided at a portion where the latent image carrier and the developer carrier are opposed to each other. The thirteenth aspect of the present invention is also achieved by a thirteenth aspect in which a regulating member which rotates so as to move in directions opposite to each other and regulates the amount of the developer on the developer carrier below the developer carrier is provided.

According to the present application, the above object is achieved according to any one of the eighth to thirteenth inventions, wherein the magnetic carrier comprises a binder resin, a magnetic metal oxide, and a nonmagnetic metal oxide. The invention is also attained by a fourteenth invention in which a resin magnetic carrier containing a high-resistance carrier produced by a polymerization method.

That is, in the first invention according to the present application, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then detects the toner amount by the detecting means. The correction is performed according to the toner amount, and the toner replenishing means is controlled.

According to the second aspect of the present invention, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then detects the toner amount by the detecting means. The correction is performed according to the difference between the toner amount and a preset reference toner amount or a difference between the detected toner amount detected by the detection unit and the toner supply unit.

Further, in the third invention according to the present application, the control means determines the toner supply time or toner supply amount supplied by the toner supply means into the developer container, based on the first table, based on the image information. Then, based on the third table, based on the detected toner amount of the detecting means based on the second table, the toner replenishing time or the toner replenishing amount determined based on the first table is corrected, and the toner replenishing means is controlled. Control.

In the fourth aspect of the present invention, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then sets the developing means to the developing means. By detecting the magnetic permeability of the developer while the apparatus is being driven, correction is made in accordance with the detected toner amount, and the toner replenishing means is controlled.

Further, in the fifth invention according to the present application, the control means determines the amount of toner to be supplied to the developer container by the toner replenishing means in accordance with the image information, and then detects the toner amount by the detecting means. The correction is performed according to the toner amount, and the toner replenishing means is controlled.

In the sixth invention according to the present application, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then detects the toner amount by the detecting means. The correction is performed according to the toner amount, and the toner replenishing means is controlled.

Further, in the seventh invention according to the present application, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then detects the toner amount by the detecting means. The correction is performed according to the toner amount, and the toner replenishing means is controlled.

Further, in the eighth invention according to the present application, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then detects the toner amount by the detecting means. The correction is performed according to the toner amount, and the toner replenishing means is controlled.

Further, according to the ninth invention of the present application, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then detects the toner amount by the detecting means. The correction is performed according to the difference between the toner amount and a preset reference toner amount or a difference between the detected toner amount detected by the detection unit and the toner supply unit.

Further, in the tenth aspect of the present invention, the control means sets the toner supply time or toner supply amount supplied by the toner supply means into the developer container to the image information based on the first table. Then, based on the third table, based on the detected toner amount of the detecting unit based on the second table, the toner replenishing time or the toner replenishing amount determined based on the first table is corrected, and the toner replenishing unit is corrected. Control.

Further, in the eleventh invention according to the present application, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information. By detecting the magnetic permeability of the developer while the developing device is being driven, correction is made in accordance with the detected toner amount, and the toner replenishing means is controlled.

Further, in the twelfth invention according to the present application, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then controls the detecting means. Correction is made in accordance with the detected toner amount, and the toner replenishing means is controlled.

Further, in the thirteenth invention according to the present application, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information. Correction is made in accordance with the detected toner amount, and the toner replenishing means is controlled.

In the fourteenth aspect of the present invention, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then determines the amount of toner to be supplied to the detecting means. Correction is made in accordance with the detected toner amount, and the toner replenishing means is controlled.

[0055]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

(First Embodiment) First, a schematic configuration of an image forming apparatus as an example of the first embodiment of the present invention will be described.
A description will be given based on FIG. In this embodiment, a case is described in which the present invention is applied to an electrophotographic digital copying machine. However, it goes without saying that the present invention can be equally applied to various other image forming apparatuses of an electrophotographic type or an electrostatic recording type. No.

In this image forming apparatus, as shown in FIG. 1, a photosensitive drum 40 serving as a drum-shaped latent image carrier on which an electrostatic latent image is formed on the outer peripheral surface, and an outer peripheral surface of the photosensitive drum 40 are defined. A primary charger 42 for charging to a potential, a semiconductor laser 36 for forming an electrostatic latent image on the outer peripheral surface charged to a specified potential by exposure, and visualizing the electrostatic latent image with a developer A developing device 44 as a developing device, a transfer charger 49 for transferring a visible image (visible image) formed on the outer peripheral surface to a recording paper 48 as a sheet-shaped recording medium, and a fixing device (not shown) are provided. ing.

As shown in FIG. 1, an image of a document 81 to be copied is projected onto an image sensor 33 such as a CCD by a lens 32. The image sensor 33 decomposes the original image into a number of pixels and generates a photoelectric conversion signal corresponding to the density of each pixel. The analog image signal output from the image sensor 33 is
The signal is sent to the image signal processing circuit 34, where it is converted into a pixel image signal having an output level corresponding to the density of the pixel, and sent to the pulse width modulation circuit 35.

The pulse width modulation circuit 35 forms and outputs a laser drive pulse having a width (time length) corresponding to the level of each input pixel image signal. That is, FIG.
As shown in FIG. 5, a wider drive pulse W is applied to a high-density pixel image signal, and a narrower drive pulse S is applied to a low-density pixel image signal. On the other hand, a drive pulse I having an intermediate width is formed.

The laser drive pulse output from the pulse width modulation circuit 35 is supplied to the semiconductor laser 36 and causes the semiconductor laser 36 to emit light for a time corresponding to the pulse width. Therefore, the semiconductor laser 36 is driven for a longer period of time for the high-density pixels, and is driven for a shorter period of time for the low-density pixels. Therefore, the photosensitive drum 4
In the case of 0, a longer range is exposed in the main scanning direction for high-density pixels and a shorter range in the main scanning direction is exposed for low-density pixels by the optical system described below. That is,
The dot size of the electrostatic latent image differs depending on the density of the pixel. Therefore, it goes without saying that the toner consumption for the high density pixels is larger than that for the low density pixels.
In FIG. 3D, the electrostatic latent images of the low, medium and high density pixels are indicated by L, M and H, respectively.

The laser beam 36a emitted from the semiconductor laser 36 is swept by a rotating multi-plane boundary 37 to direct a lens 38 such as an f / θ lens and the laser beam 36a toward a photosensitive drum 40 as a latent image carrier. 39 forms a spot image on the photosensitive drum 40. Thus, the laser beam 36a scans the photosensitive drum 40 in a direction substantially parallel to the rotation axis of the photosensitive drum 40 (main scanning direction).
An electrostatic latent image will be formed.

The photosensitive drum 40 is an electrophotographic photosensitive drum having amorphous silicon, selenium, OPC and the like on its surface and rotating in the direction of the arrow. 42 uniformly charges. Thereafter, exposure scanning is performed with a laser beam modulated in accordance with the image information signal described above, whereby an electrostatic latent image corresponding to the image information signal is formed. The electrostatic latent image is a two-component developer 4 in which toner particles and carrier particles are mixed.
3 (hereinafter, referred to as a developer 43) is reversely developed by a developing device 44 to form a visible image (toner image). Here, the reversal development is a development method in which a toner charged to the same polarity as the latent image is attached to a region of the photoconductor exposed to light, and the toner is visualized.

The toner image is formed by two rollers 45 and 46.
A transfer charger 4 is mounted on a transfer material 48 held on a transfer material carrying belt 47 which is stretched therebetween and is driven endlessly in the direction of arrow c in the figure.
9 is transcribed.

The transfer material 48 onto which the toner image has been transferred is separated from the transfer material carrying belt 47, is conveyed to a fixing device (not shown), and is fixed to a permanent image. Further, the residual toner remaining on the photosensitive drum 40 after the transfer is removed by the cleaner 50 thereafter.

Although only a single image forming station (including a photosensitive drum 40, an exposing device 41, a primary charging device 42, a developing device 44, etc.) is shown in FIG. In the case of (1), for example, image forming stations for each color of cyan, magenta, yellow, and black are sequentially arranged on the transfer material carrying belt 47 along the moving direction, and a document is placed on the photosensitive drum of each image forming station. Are sequentially formed, developed by a developing device having a corresponding color toner, and sequentially transferred to a transfer material 48 held and conveyed by a transfer material carrying belt 47. Will be.

The developing device 4 provided in the image forming apparatus shown in FIG.
FIG. 2 shows a schematic configuration of No. 4.

The developing device 44 includes a developer container 44a, a developing sleeve 54 as a developer carrier, a toner replenishing tank 60 as a toner replenishing unit, a toner concentration detecting sensor 80 as a detecting unit, and image information from a document 81. The toner supply tank 60 has a CPU 67 as a control means capable of correcting the amount of toner to be supplied to the developer container 44a in accordance with the detection result of the toner concentration detection sensor 80.

As shown in FIG. 2, the developing device 44 has a developing sleeve 54 disposed opposite to the photosensitive drum 40, and a first partition 51 in which the inside of the developer container 44a extends in the vertical direction. Chamber (developing chamber) R1 and second chamber (stirring chamber)
R2.

A non-magnetic developing sleeve 54 rotating in the direction of arrow f is disposed in the first chamber R1, and a magnet 55 is fixedly disposed in the developing sleeve 54.

The developing sleeve 54 carries and conveys a layer of a two-component developer (including a magnetic carrier and a non-magnetic toner) whose thickness is regulated by a blade 56, and the developer 43 in a developing area opposed to the photosensitive drum 40. Is supplied to the photosensitive drum 40 to develop the electrostatic latent image. In order to improve the development efficiency, that is, the rate at which toner is applied to the latent image, a development bias voltage in which a DC voltage is superimposed on an AC voltage is applied to the development sleeve 54 from a power supply 57.

A screw 58 and a screw 59 for stirring the developer in the developer container 44a are arranged in the first chamber R1 and the second chamber R2, respectively. The screw 58 stirs and transports the developer in the first chamber R1.
The screw 59 stirs and transports the toner 63 supplied from the toner discharge port 61 of the toner replenishing tank 60 to be described later by the rotation of the transport screw 62 and the developer 43 already in the developer container 44a. To make the toner concentration uniform.

The partition wall 51 is formed with a developer passage (not shown) for connecting the first chamber R1 and the second chamber R2 to each other at the near side and the rear end in FIG. Due to the conveying force of the screws 58 and 59, the developer in the first chamber R1 whose toner concentration has been reduced due to the toner consumption due to the development moves from one passage into the second chamber R2, and the toner in the second chamber R2. The developer whose concentration has been restored moves from the other passage into the first chamber R1.

The developer container 4 is developed by developing the electrostatic latent image.
4a to correct for the changed developer concentration, ie,
In order to control the amount of toner to be supplied to the developer container 44a, the level of the output signal of the image signal processing circuit 34 is counted for each pixel. This counting is performed as follows in the present embodiment.

First, the output signal of the pulse width modulation circuit 35 is supplied to one input of an AND gate 64,
The other input of the D gate is supplied with a clock pulse from the clock pulse oscillator 65 (the pulse shown in FIG. 3B). Therefore, as shown in FIG. 3C, the AND gate 64 outputs a number of clock pulses corresponding to the respective pulse widths of the laser driving pulses S, I and W, that is, a number of clock pulses corresponding to the density of each pixel. A pulse is output.

The number of clock pulses is integrated by the counter 66 for each image, and the video count is calculated. The pulse integration signal (video count number) for each image from the counter 66 indicates that the toner image of the original 81 is 1
This corresponds to the amount of toner consumed from the developing device 44 to form the image.

Therefore, the above-described pulse integration signal is transmitted to the CPU 67.
And stored in the RAM 68. CPU67
Is a conveying screw 62 required to supply an amount of toner 63 corresponding to the amount of toner consumed from the developing device 44 from the toner replenishing tank 60 to the developer container 44a provided in the developing device 44 based on the pulse integration signal. , And controls the motor drive circuit 69 to drive the motor 70 only during the calculated time.

Thus, in general, if the pulse integration value is large, the driving time of the motor 70 becomes longer, and
If the pulse integration value is small, the driving time of the motor 70 is shorter.

The driving force of the motor 70 is transmitted to the conveying screw 62 via a gear train 71, and the conveying screw 62 conveys the toner 63 in the toner replenishing tank 60 and supplies a predetermined amount of toner to the developing device 44. The toner is supplied every time the development of one image is completed or during the development.

By the way, the developing device 44 uses the density information obtained by photoelectrically converting the image of the original to be copied as described above.
Is not a direct detection of the actual toner concentration of the developer and a replenishment of the toner based on the detected toner concentration, but a kind of inferred replenishment. If there is a change from the expected amount of toner replenishment from the replenishing tank 60 or the amount of toner consumption from the developing device 44, or if the consumption system and the replenishment system fluctuate, the developer container 4
The toner concentration of the developer 43 in 4a gradually shifts from the initial set value. If this deviation is not corrected, the toner density will greatly deviate from the allowable range of the initial set value.

For this reason, in the present embodiment, the toner concentration detecting sensor 80 which is a detecting means using the inductance of the coil is provided in the developer container 44a, and the two-component developer in the developer container 44a is always driven when the developing device 44 is driven. Is detected,
The CPU 67 controls the driving of the motor 70 (supply of the developer 63 from the toner replenishing tank 60) so as to correct the above-mentioned deviation in accordance with the detected toner concentration (detected toner amount) of the toner concentration detection sensor 80. ing.

The toner density detecting sensor 80 utilizing the inductance of the coil detects a change in the apparent magnetic permeability μ of the carrier contained in the developer 43 in a certain volume near the sensor. When the magnetic susceptibility increases, it means that the T / D in the developer has decreased in a certain volume, which means that the amount of toner in the developer has decreased.
Is larger than the initial output signal. Conversely, when the magnetic permeability decreases, the T /
This means that the D ratio has increased, which means that the amount of toner in the developer has increased. In this case, the output signal of the toner density detection sensor 80 is smaller than the initial output signal.

The output signal of the toner density detecting sensor 80 is supplied to the input of the comparator 75. A reference signal corresponding to a specified toner density of the developer 43 (a preset toner density) is input to the comparator 75 in advance.

Accordingly, the comparator 75 compares the specified toner density with the actual toner density in the developer container 44a.
Generates an output signal indicating that the actual toner density of the developer 43 in the developer container 44a is higher than a specified value or an output signal indicating that the toner density is lower than the specified value. . When there is no difference between the two input signals, an output signal indicating the difference may be generated. Comparator 7
The output signal of No. 5 is supplied to the CPU 67.

In the present embodiment, as shown in FIG. 4, the CPU 67 sets a table 1 representing the relationship between the video count number, the output level such as the gradation level, and the optical density.
Based on the video count data based on the result of Table 1, the video count number and the toner replenishment time (replenishment amount) for replenishing the toner during or during formation of a toner image such as during continuous copying. Table 2 as a first table representing the relationship, Table 3 as a second table representing the relationship between the output of the toner density detection sensor 80 and the toner supply time, the toner supply amount based on the video count number in Table 2, And a table 4 that is a third table that indicates a relationship with the toner supply amount by the toner density detection sensor 80.

Next, C having tables 1, 2, 3, and 4
The control operation of the image forming apparatus of this embodiment using the PU 67 will be described with reference to the flowchart shown in FIG.

First, when the start button is pressed to copy the original, the original 81 is read by the image sensor 33 as described above in block S101, and the photoelectric conversion corresponding to the density of each pixel of the image of the original 81 is performed. A signal is generated.

Next, in block S102, the counter 66 counts the output level of each pixel and integrates to calculate a video count. This pulse integrated value (a value obtained by integrating the video count number) is sent to the CPU 67,
In block S103, the toner replenishment time for one image (the replenishment amount may be used), that is, the number of rotations of the screw 62, is determined by the table 2, and the copying operation is started in block S104. An image forming operation such as transfer is performed.

When one toner image is formed, in step S106, the screw 62 is rotated by the rotation speed determined as described above before forming the next toner image or during the formation of the toner image. Supply toner.

The toner image forming and toner replenishing operations are as follows.
This is repeated for the number of copies set by the operator. At this time, the toner concentration detection sensor 80 starts operating in block S105 when the developing device 44 is driven, and the developer container 4
4a, the actual toner concentration of the developer 43 is measured. In block S107, the measured value of the toner concentration of the toner concentration detection sensor 80 is compared with a reference value to calculate the difference, and in block S108, the difference is calculated. The difference value is converted from the table 4 of the CPU 67 into an excessive or insufficient toner supply time per one image.

Then, in decision block S109, it is determined from the comparison result of the measured toner density of the toner density detection sensor 80 with the reference value whether or not the toner is excessively replenished. YES), in block S110, 1 calculated in block S108
A command to subtract the excessive toner supply time per sheet is given to the block S103, and the block S103 is set at the next toner supply operation.
Subtraction is performed from the toner supply time per image calculated in step 103.

On the other hand, if it is determined in the determination block S109 that the toner supply is insufficient (NO),
In block S111, a command to add the insufficient toner supply time per sheet calculated in block S108 is given to block S103, and the toner supply time per sheet image calculated in block S103 at the time of the next toner supply operation is changed. to add. Hereinafter, the same operation is repeated.

As described above, the toner density detection sensor 80
Thus, when the developing unit 44 is driven, the actual toner concentration of the developer is directly detected, the actual toner concentration is compared with a reference value to calculate a difference value between the detected toner concentration and the difference value. Calculates the excessive or insufficient toner replenishment time (replenishment amount) for one image by using the tables 1, 2, 3, and 4 of the image and corrects the toner replenishment time (replenishment amount) calculated at the time of the next toner replenishment operation. Therefore, there is an advantage that errors in the replenishment system due to aging or the like can always be corrected.

Further, instead of operating the toner density detection sensor 80 only at the time of the copy operation (or at the time of the continuous copy operation) as in the present embodiment, for example, the toner density detection before turning off the power supply of the apparatus the day before is performed. The last data detected by the sensor 80, that is, an excessive or insufficient toner replenishment time (replenishment amount) per image, is stored in memory, and the apparatus is turned on the next day to operate the developing device 44. Then, the toner concentration detection sensor 80 is operated to calculate the excessive or insufficient toner replenishment time per one image, and an operation of correcting the toner replenishment time (replenishment amount) from the comparison of both values is added. Is also good.

In a full-color copying machine or the like, the amount of toner replenishment differs for each color even if toner is replenished for a certain period of time due to differences in physical properties of toners of different colors. In this case, a correspondence table between the toner replenishment time and the toner replenishment amount is provided for each toner of each color, and the time for replenishing the toner of each color is determined with reference to this table, and the toner is replenished. In this case, the replenishment accuracy is improved.

Further, the present invention can be applied to an image forming apparatus which performs shading expression of an image by a dither method. In addition, an image forming apparatus which forms a toner image by an image information signal output from a computer or the like instead of copying a document. The present invention can be applied to an apparatus.

Of course, as described above, the present invention can be applied to a color image forming apparatus. In this case, the above-described image forming unit may be provided for each color along the traveling direction of the transfer material carrying belt 47. However, the image of the document may be color-separated to form an image information signal for each color, and toner supply may be controlled for each color in the same manner as described above.

The present invention is also applicable to a color image forming apparatus having a configuration in which a plurality of developing devices are arranged around a photosensitive drum. Further, it goes without saying that various modifications and changes can be made as necessary.

Further, the toner particles used in the present embodiment are spherical polymerized toners. The method of manufacturing the toner particles is as follows. In the present embodiment, a monomer composition obtained by adding a colorant and a charge control agent to a monomer of the polymerization method is used. The product was suspended and polymerized in an aqueous medium to obtain spherical toner particles. The production method is not limited to the above-mentioned method, and may be produced by an emulsion polymerization method or the like, or may contain other additives.

[0099] The shape factor of the spherical polymerized toner obtained by this process is SF ₁ is 100 to 140, SF ₂ is 100 to
20. The SF ₁ and SF ₂ are Hitachi FE-
Using a SEM (S-800), 100 toners are sampled at random, and the image information is introduced into an image analyzer (Lusex3) manufactured by Nicole via an interface, analyzed, and calculated by the following equation. These values were defined as shape factors SF1 and SF2 in the present invention. SF ₁ = (MXLNG ² / AREA) × (π / 4) × 10
0 SF ₂ = (PERI ² / AREA) × (π / 4) × 100 (AREA: maximum toner projected area, MXLNG: absolute maximum length, PERI: maximum circumference) SF ₁ indicates the degree of sphericity, and The shape gradually becomes irregular from a spherical shape, and SF ₂ indicates the degree of irregularity.

[0101] For the shape factor of the spherical polymerized toner, the shape factor of the conventional pulverized toner SF ₁ is 180 to 220,
Since SF ₂ is 180 to 200, spherical polymerized toner is seen that the shape of the toner particles is close to a perfect circle as compared to conventional pulverized toners.

In the spherical polymerized toner, the change rate of the shape factor of the toner particles due to the deterioration of the agent is smaller than that of the conventional pulverized toner. change, SF ₁ in pulverized toner is 120 to 150, whereas SF ₂ is close to 120 to 140 and a spherical, spherical polymerized toner SF ₁ is 100 to 12
0, SF ₂ is there is little change in shape and 100 to 120. This is because the crushed toner is agitated, and the uneven surface layer is scraped off by the friction caused by the carrier or toner contact.The shape changes close to a sphere, causing a large change in shape. This indicates that the shape change is small due to the small number of factors.

From the above, the pulverized toner has a large change in the shape of the toner particles, and therefore a large change in the contact area between the agents, and a large change in the porosity and the bulk density. A large change in porosity and bulk density means a large fluctuation in the output of the toner concentration detection sensor 80 utilizing the inductance of the coil, and thus it is difficult to use the toner concentration detection sensor. As described above, since the change in the shape of the toner particles is small, the change in the bulk density is also small, and the output fluctuation of the toner density detecting sensor 80 is also small, so that more accurate toner density detection can be performed.

The toner replenishment data obtained from the detection result of the toner density detection sensor 80 is sent to the CPU 26 and compared with the video count data, so that the toner density can be detected more accurately.

Next, the magnetic carrier used in this embodiment will be described. In the present embodiment, by changing the material of the magnetic carrier, that is, by using a high-resistance magnetic carrier, a change in the toner charge amount with respect to a change in the T / D ratio of the developer is suppressed, and the volume of the two-component developer is further reduced. Density fluctuation is suppressed.

FIG. 6 shows a change in toner charge amount with respect to a change in T / D ratio between a ferrite-based magnetic carrier conventionally used and a high-resistance carrier capable of suppressing a tribo change amount in the present embodiment. It is a thing.

It can be seen that the low-resistance carrier has less change in the toner charge amount than the conventional ferrite-based magnetic carrier. The present inventor considered this phenomenon as follows.

[0107] high resistance carrier and a ferrite based magnetic carrier of the present embodiment is different from its shape factor, SF ₁ of the high-resistance carrier, respectively 100 to 140, SF ₂ 10
For the ferrite-based magnetic carrier SF _1,
But 140 to 180, the range of the T / D ratio of the comparison measurement for SF ₂ is 145 to 185 and the surface layer is uneven, because of large contact area towards ferritic magnetic carrier and toner, and the toner The triboelectricity of the carrier is high due to the contact of the carrier, and the resistance of the carrier itself is low, so that the accumulation of the electric charge in the carrier is small and the carrier is hardly saturated.

However, when the T / D ratio increases, the area of the carrier covered by the toner increases, and the contact area between the toner and the carrier decreases. Therefore, the toner charge amount decreases as compared with the case where the T / D ratio is low. come. On the other hand, a high resistance carrier has a specific resistance of 1 × 10 ¹⁰ to 1 × 10 ¹⁴ Ω.
Cm, the charge amount provided by contact with the toner is accumulated, and the toner charge amount is likely to be saturated. Therefore, even if the T / D ratio changes, the change in the saturated toner charge amount of the carrier is small, and it is considered that the change in the toner charge amount is small.

As described above, if the change in the toner charge amount with respect to the change in the T / D ratio can be suppressed, it is possible to have a developer configuration in which the change in the bulk density of the developer is smaller by combining with the spherical polymerization toner. More accurate toner toner concentration data can be sent to the CPU 26 by the toner concentration detection sensor 80 that detects the magnetic permeability of the carrier using the inductance of the coil, and changes in the supply amount of the supply system and the consumption amount of the consumption system. Therefore, if the developer T / D ratio is likely to fluctuate, the video count data can be corrected more accurately.

FIG. 8 shows a conventional ferrite-based magnetic carrier, and FIG. 7 shows a 400-line PWM with respect to a change in the T / D ratio in the high-resistance carrier of the present embodiment.
The potential difference between the average potential of the light exposure portion of the dot latent image and the DC voltage component when a 17-tone image is output by (modulating the width of the laser drive pulse current with respect to the density of the recorded image) Vcont) and a change in image density. As can be seen from FIG. 8, by suppressing the change in the toner charge amount with respect to the change in the T / D ratio in the present embodiment, the change in the image density with respect to the change in the T / D ratio could be reduced.

Therefore, by using the high-resistance carrier of the present embodiment, the change in the bulk density of the developer is small, and the toner density detecting sensor 8 utilizing the inductance of the coil is used.
At 0, not only the more accurate developer toner concentration data can be obtained, but also the supply amount of the supply system and the consumption amount of the consumption system, which are problems in using the developer concentration control of the video count system, have changed. In this case, even if the developer T / D ratio fluctuates somewhat, it can be said that the magnetic carrier has a small deviation in image density and can obtain a stable image quality.

The present inventor has set forth the above high-resistance carrier as follows:
A resin magnetic carrier composed of a binder resin, a magnetic metal oxide, and a non-magnetic metal oxide was produced by a polymerization method, but if the change in toner charge amount can be suppressed by another manufacturing method, the carrier is used. No problem.

Therefore, according to the present embodiment, the toner density of the developer in the developer container 44a is always directly detected by the toner density detection sensor 80, and one image is changed according to the change of the toner density. The toner replenishment time (replenishment amount) is calculated by adding or subtracting the toner replenishment time (replenishment amount) from the toner replenishment time (replenishment amount) calculated at the time of the next image forming operation (at the time of development processing). By correcting this, even if the supply amount of the supply system and the consumption amount of the consumption system fluctuate, these can be easily corrected, and the toner concentration (that is, toner particles and carrier) in the developer container 44a can be corrected. (Mixing ratio of particles) can always be maintained within the allowable range of the initial set value (specified value).

Further, according to the present embodiment, by using the spherical polymerized toner, the stirring of the developing unit 44 during operation, the deterioration of the developer due to the agent compression, and the friction between the developers, the shape of the toner particles is reduced. The change in bulk density due to the change, the change in the bulk density of the developer due to the change in the shape of the toner, or the toner charge due to the compression of the developer is suppressed, and the change in the bulk density due to repulsion between carriers is prevented. By using a carrier with a suppressed change in the amount of charge, the change in the bulk density of the developer can be suppressed, and the toner concentration in the developer container 44a can be more accurately controlled by the toner concentration detection sensor 80. Due to small space,
It is possible to perform toner density control suitable for a low-cost copying machine or image forming apparatus.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. In addition, about the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

In the first embodiment, in order to suppress the fluctuation in the bulk density of the two-component developer, a non-magnetic toner of the two-component developer is changed to a spherical toner obtained by polymerization, and the material of the magnetic carrier is changed. That is, the use of a high-resistance magnetic carrier suppresses a change in the bulk density of the two-component developer.

In the first embodiment, the developing sleeve 54 as a developer carrier is provided with a photosensitive drum 4 as a latent image carrier.
In order to prevent the developer 43 from coating unevenly on the developing sleeve 54, the developer is stored near the regulating blade 56 of the developing sleeve 54, and the developer is compressed. The agent is gradually compressed mechanically.

Since the developing sleeve 54 is configured to rotate in the forward direction with respect to the photosensitive drum 40, the developing sleeve 54 must pump the developer from the developer container 44a by the action of the magnet roller 55. ,
The magnets 55 having a high magnetic force are used for the magnetic poles N2 and S2 of the magnet roller 55, and the developer 43 is pumped up by the cooperative action. And magnetically compressed, and as a result, the developer 43
The bulk density change or the bulk density change due to the embedding of the external additive occurs, and the developer 43
This causes a change in the magnetic permeability.

In response to this phenomenon, as shown in FIG. 9, the developing device 90 as the developing device in this embodiment moves the developing sleeve 82 as the developer carrier in the rotation direction of the photosensitive drum 88 as the latent image carrier. On the other hand, the photosensitive drum 88 and the developing sleeve 82 are rotated so as to move in the opposite directions to each other (in the direction of arrow g with respect to the direction of arrow a), so that the agent between the developing sleeve 82 and the regulating blade 84 is moved. The compression density is reduced, and the bulk density change of the developer 87 due to the shape change of the toner or the bulk density change due to the embedding of the external additive is minimized. This is for suppressing the output fluctuation with respect to the fluctuation.

As shown in FIG. 9, in a configuration in which the developing sleeve 82 is rotated so as to move in opposite directions to each other at the opposing portion of the photosensitive drum 88 and the developing sleeve 82 with respect to the rotation direction of the photosensitive drum 88, After the developer in the developing chamber R1 is pumped up by the magnetic force of the S3 pole and the developer 87 is applied to the developing sleeve 82, the developer 87 applied to the developing sleeve 82 is regulated by the regulating blade 84 so that the coating on the developing sleeve 82 is performed. Controlling the amount.

Therefore, as compared with the forward rotation of the developing sleeve 40 in which the developer is gradually clogged near the regulating blade 56 of the developing sleeve 54 as in the developing device shown in FIG.
In the present embodiment, since the developer is not pumped up from the developer container, the magnet roller 8 of the developing sleeve 82 is not used.
3, the magnetic force of only the magnetic pole S3 is N2 in the conventional implementation system.
As compared with the case of the S2 pole, the magnetic binding force between the developing sleeve 82 and the regulating blade 84 can be weakened, and the agent between the developing sleeve 82 and the regulating blade 84 for preventing coating unevenness on the developing sleeve 82 can be reduced. There is no need to make a spill.

Therefore, the compressibility of the developer in the vicinity of the regulating blade 84 of the developing sleeve 82 is small, and as a result, the deterioration of the developer can be prevented, and the fluctuation of the toner charge amount can be suppressed. is there.

This can suppress a change in the bulk density of the developer due to a change in the shape of the toner, or a change in the amount of toner charged due to the compression of the developer, leading to a reduction in the change in the bulk density due to repulsion between the developers. As compared with the conventional example, the output fluctuation of the toner density detection sensor using the inductance of the coil can be suppressed.

Therefore, according to the present embodiment, the toner concentration of the developer in the developer container 90a is always directly detected by the toner concentration detection sensor 92, and one image is changed according to the change in the toner concentration. The toner replenishment time (replenishment amount) is calculated by adding or subtracting the toner replenishment time (replenishment amount) from the toner replenishment time (replenishment amount) calculated at the time of the next image forming operation (at the time of development processing). By correcting this, even if the supply amount of the supply system and the consumption amount of the consumption system fluctuate, these can be easily corrected, and the toner concentration (that is, the toner particles and the carrier) in the developer container 90a can be corrected. (Mixing ratio of particles) can always be maintained within the allowable range of the initial set value (specified value).

Further, according to the present embodiment, by using the spherical polymerized toner, the developer is deteriorated due to agitation during the operation of the developing device 90, the agent compression, and the like, and the toner particles are shaped by the friction between the developers. The development sleeve 82 is rotated so as to move in the opposite direction to the rotation direction of the photoconductor drum 88 at the opposing portion of the photoconductor drum 88 and the development sleeve 82 (the direction of arrow a). (In the direction of arrow g), the deterioration of the developer due to the compression of the developer in the vicinity of the regulating blade 84 of the developing sleeve 82 is prevented, the change in the bulk density of the developer due to the change in the shape of the toner, or the change in the developer By suppressing toner charge due to compression, preventing changes in bulk density due to repulsion between carriers, and further using a carrier in which toner charge changes are suppressed, developer It is it is possible to suppress the density change,
The toner density in the developer container 90a can be controlled more accurately by the toner density detection sensor 92, and accordingly, the toner density control suitable for a small space, low cost copying machine or image forming apparatus can be performed. it can.

[0126]

As described above, according to the first aspect of the present invention, the control means determines the amount of toner to be supplied to the developer container by the toner replenishing means in accordance with the image information. Since the toner replenishing unit is controlled by correcting the amount of toner detected by the detecting unit, the amount of toner in the developer in the developer container is accurately detected, and the toner is replenished. The toner concentration in the developer container can be maintained.

According to the second invention of the present application,
The control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then determines the amount of toner detected by the detecting means and a predetermined reference toner amount, or the amount detected by the previously detecting means. Correction is performed according to the difference between the detected toner amount and the toner replenishment means, so that the toner amount in the developer in the developer container is accurately detected, and the toner is replenished. The toner concentration in the developer container can be maintained.

Further, according to the third invention of the present application, the control means determines the toner supply time or toner supply amount supplied by the toner supply means into the developer container according to the image information based on the first table. After the determination, the toner replenishing time or the toner replenishment amount determined according to the detected toner amount of the detecting means based on the second table based on the third table is corrected to control the toner replenishing means. By accurately detecting the amount of toner in the developer in the developer container and replenishing the toner, the toner concentration in the developer container can be maintained.

According to the fourth invention of the present application,
The control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then detects the detected toner by detecting the magnetic permeability of the developer while the developing device is being driven. Since the toner replenishing means is controlled by correcting the amount according to the amount, the toner amount in the developer in the developer container is accurately detected, and the toner is replenished. Can be kept.

Further, according to the fifth invention of the present application, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then detects the toner amount detected by the detecting means. Since the toner replenishing means is controlled by correcting the amount according to the amount, the toner amount in the developer in the developer container is accurately detected, and the toner is replenished. Can be kept.

Further, according to the sixth invention of the present application,
The control means controls the toner replenishing means by determining the amount of toner supplied by the toner replenishing means into the developer container in accordance with the image information and correcting the toner amount in accordance with the detected toner amount of the detecting means. Therefore, the toner concentration in the developer container can be maintained by accurately detecting the amount of toner in the developer in the developer container and replenishing the toner.

Further, according to the seventh aspect of the present invention, after the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, the control means detects the amount of toner detected by the detecting means. Since the toner replenishing means is controlled by correcting the amount according to the amount, the toner amount in the developer in the developer container is accurately detected, and the toner is replenished. Can be kept.

Further, according to the eighth invention of the present application,
The control means controls the toner replenishing means by determining the amount of toner supplied by the toner replenishing means into the developer container in accordance with the image information and correcting the toner amount in accordance with the detected toner amount of the detecting means. Therefore, the toner concentration in the developer container can be maintained by accurately detecting the amount of toner in the developer in the developer container and replenishing the toner.

Further, according to the ninth invention of the present application, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then determines the amount of toner detected by the detecting means. The toner replenishing unit is controlled by correcting the amount in accordance with the difference between the amount and a preset reference toner amount or the amount of toner detected by the detecting unit before. By accurately detecting the amount of toner inside and replenishing the toner, the toner concentration in the developer container can be maintained.

Further, according to the tenth aspect of the present invention,
The control means determines a toner supply time or a toner supply amount to be supplied to the developer container by the toner supply means in accordance with the image information based on the first table, and then determines the detection means based on the second table based on the third table. The toner replenishment time or the toner replenishment amount determined according to the detected toner amount is corrected to control the toner replenishment means. Therefore, the toner amount in the developer in the developer container is accurately detected, and the toner , The toner concentration in the developer container can be maintained.

Further, according to the eleventh aspect of the present invention, after the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, the control means sets the developing means to The amount of toner in the developer in the developer container can be accurately determined by correcting the amount of toner detected by detecting the magnetic permeability of the developer while the apparatus is operating, and controlling the toner replenishing means. The toner concentration in the developer container can be maintained by replenishing the toner.

Further, according to the twelfth aspect of the present invention, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then detects the amount of toner by the detecting means. The toner replenishing means is controlled in accordance with the correction in accordance with the amount of toner. Therefore, the amount of toner in the developer in the developer container is accurately detected, and the toner is replenished. The concentration can be maintained.

Further, according to the thirteenth aspect of the present invention, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then detects the toner amount by the detecting means. The toner replenishing means is controlled in accordance with the correction in accordance with the amount of toner. Therefore, the amount of toner in the developer in the developer container is accurately detected, and the toner is replenished. The concentration can be maintained.

Further, according to the fourteenth aspect of the present invention, the control means determines the amount of toner to be supplied into the developer container by the toner replenishing means in accordance with the image information, and then detects the toner amount by the detecting means. The toner replenishing means is controlled in accordance with the correction in accordance with the amount of toner. Therefore, the amount of toner in the developer in the developer container is accurately detected, and the toner is replenished. The concentration can be maintained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view illustrating a schematic configuration of a developing device included in the image forming apparatus of FIG.

3 is a waveform diagram illustrating a method of counting density information of an image information signal in the image forming apparatus of FIG.

FIG. 4 is an explanatory diagram illustrating a table included in a control unit of the image forming apparatus in FIG. 1;

FIG. 5 is a flowchart for explaining a basic operation of the first embodiment of the present invention.

FIG. 6 shows a change in toner charge amount with respect to a change in the T / D ratio of a developer when a high-resistance magnetic carrier used in the first embodiment is used and when a conventional ferrite-based magnetic carrier is used. It is a graph shown.

FIG. 7 is a graph showing Vcont with respect to a change in T / D ratio when a high-resistance magnetic carrier used in the first embodiment is used.
6 is a graph showing the relationship between the image density and the number of strokes.

FIG. 8 is a graph showing the relationship between Vcont and image density with respect to a change in T / D ratio when a conventional ferrite-based magnetic carrier is used.

FIG. 9 is a schematic sectional view illustrating a schematic configuration of a developing device included in an image forming apparatus used in a second embodiment of the present invention.

FIG. 10 is an explanatory diagram illustrating an overall configuration of an example of a conventional image forming apparatus.

[Explanation of symbols]

 Reference Signs List 40 photosensitive drum (latent image carrier) 43 two-component developer 44 developing device (developing device) 44a developer container 67 CPU (control means) 80 toner density detection sensor (detection means) 87 two-component developer 88 photosensitive drum (Latent image carrier) 90 Developing device (developing device) 90a Developer container 92 Toner density detection sensor (detection means) 48 Transfer material (recording medium)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 9/10 G03G 15/08 507X (72) Inventor Masaru Hibino 3- 30-2 Shimomaruko 3-chome, Ota-ku, Tokyo Within Canon Inc. (72) Inventor Ichiro Ozawa 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term within Canon Inc. (reference) 2H005 AA15 BA03 BA11 BA15 CB04 DA01 DA08 FA02 2H077 AB02 AB15 AB18 AC02 AD02 AD06 AD13 AD18 AD36 BA01 DA10 DA15 DA42 DA52 DB02 EA03 FA19 GA12

Claims (14)

[Claims] 1. Two-component development containing toner and carrier
The developer is carried on a developer carrier and is formed according to image information.
Applying the toner to the electrostatic latent image on the latent image carrier
And a developing device for visualizing the electrostatic latent image by
A developer container containing a two-component developer and a toner container
Toner supply means for supplying toner,
The step determines the amount of toner supplied to the developer container according to the image information.
And a control means for controlling the
Detecting the magnetic permeability inside the image agent container allows the developer container
Two-component developer having detecting means for detecting the toner amount of
Indicates that the toner is a non-magnetic toner having spherical particles
A is the maximum projected area, where L is the absolute maximum length of the carrier particles.
Is A and the maximum circumference is P, SF ₁= (L^Two/
A) Spherical coefficient SF expressed by × (π / 4) × 100₁But
100 or more and 140 or less, SF_Two= (P^Two/ A) × (π /
4) Spherical coefficient SF expressed by × 100_TwoIs over 100
120 or less and the specific resistance is 1 × 10^TenΩ · cm or more
1 × 10¹⁴Ω · cm or less magnetic carrier
The column indicates that the toner replenishing means is in charge of the developer volume according to the image information.
The amount of toner supplied to the container is compensated according to the detection result of the detection means.
A developing device characterized in that it can be corrected. 2. The control device according to claim 1, wherein the toner supply unit controls the toner supply unit in accordance with a difference between the detected toner amount of the detection unit and a preset reference toner amount or a detected toner amount detected by the detection unit. The developing device according to claim 1, wherein the amount of toner supplied to the developing device is adjustable. A first table for converting the image information into a toner replenishing time or a toner replenishing amount of the toner supplying unit; a control unit configured to convert the detected toner amount of the detecting unit into the toner replenishing time or the toner replenishing amount of the toner supplying unit; The developing device according to claim 1, further comprising a second table to be converted and a third table indicating a relationship between the first table and the second table. 4. A detecting means disposed at a position where the flow rate of the developer is constant and the flow is regular, and detects a change in the magnetic permeability of the developer by detecting the toner concentration in the developer container when the developing device is driven. The developing device according to any one of claims 1 to 3, wherein the developing device is configured to be able to detect the developing device. 5. The non-magnetic toner has a spherical coefficient SF ₁ of 10
5. The method according to claim 1, wherein the spherical coefficient SF ₂ is not less than 100 and not more than 120, and not less than 0 and not more than 140.
The developing device according to claim 1. 6. The developer carrier rotates at opposite portions of the latent image carrier and the developer carrier so as to move in directions opposite to each other, and is disposed below the developer carrier on the developer carrier. The developing device according to claim 1, further comprising a regulating member that regulates an amount of the developer. 7. The magnetic carrier according to claim 1, wherein the magnetic carrier is a high-resistance carrier obtained by polymerizing a resin magnetic carrier containing a binder resin, a magnetic metal oxide, and a nonmagnetic metal oxide. Item 7. The developing device according to any one of items 6. 8. An image forming apparatus for recording an image formed by a series of image forming processes on a recording medium,
An image forming apparatus comprising the developing device according to claim 1. 9. The controller according to claim 6, wherein the toner supply unit supplies the toner amount to the developer container according to a difference between the detected toner amount of the detection unit and a preset reference toner amount or a previously detected toner amount. The image forming apparatus according to claim 8, wherein the image forming apparatus is adjustable. 10. A control device comprising: a first table for converting image information into a toner replenishing time or a toner replenishing amount of a toner supplying unit; The image forming apparatus according to claim 8, further comprising a second table to be converted and a third table indicating a relationship between the first table and the second table. 11. The detecting means is provided at a position where the flow rate of the developer is constant and the flow is regular, and can detect the toner concentration in the developer container when the developing device is driven. The image forming apparatus according to claim 8. 12. The non-magnetic toner has a spherical coefficient SF ₁ of 1
Is not less than 00 and not more than 140, and the spherical coefficient SF ₂ is 100
The image forming apparatus according to claim 8, wherein the number is equal to or less than 120. 13. The developer carrying member rotates so as to move in opposite directions to each other at a portion where the latent image carrying member and the developer carrying member face each other, and the developer carrying member is provided below the developer carrying member. 9. The image forming apparatus according to claim 8, further comprising a regulating member for regulating a developer amount.
The image forming apparatus according to claim 12. 14. A magnetic carrier comprising: a binder resin;
The image forming apparatus according to any one of claims 8 to 13, wherein the resin magnetic carrier containing a magnetic metal oxide and a nonmagnetic metal oxide is a high-resistance carrier produced by a polymerization method. .