JPH11160978A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly control the flowability of developer and to maintain a high-quality image by detecting the flowability of the developer in a developing device and adding additive to the developer. SOLUTION: A developing device driving motor and a developer stirring shaft 8 are coupled through a torque sensor 9. Based on the detected result of the sensor 9, the flowability of the developer is judged. When the torque T of the shaft 8 is increased, it is judged that the flowability of the developer is deteriorated. Then, when the detected result of the sensor 9 becomes larger than a prescribed value, silica is supplied to the inside of the developing device 3 from a silica hopper 10 in order to improve the flowability. The silica is supplied to the inside of the developing device 3 by rotating a silica supply motor in prescribed time. After the silica is supplied, the shaft 8 is rotated by the prescribed number of times in order to sufficiently mix the silica and the developer. Thereafter, the torque T of the shaft 8 is detected again.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus using a two-component developer, such as a copying machine, a facsimile, a laser printer, and the like.

[0002]

2. Description of the Related Art Image output of an electrophotographic image forming apparatus is performed by the following process. That is, first, the charging device uniformly charges the surface of the image carrier. Thereafter, an electrostatic latent image is formed by the exposure device. The electrostatic latent image is supplied with toner by a developing device, visualized on an image carrier, transferred to a transfer paper by a transfer device, and an image is output. The residual toner remaining on the surface of the image carrier after the transfer is removed by a cleaning device. Further, in the area other than the area of the electrostatic latent image, the toner adhered to the image carrier and not transferred is also removed by the cleaning device. Previously, the collected toner removed by the cleaning device was generally discarded before. However, in recent years, this collected toner has been returned to the developing device and reused from the viewpoint of resource saving and reduction of industrial waste. In a machine that performs such toner recycling, unused toner (new toner) and collected toner (recycled toner) in the developing device are mixed, so that the background stain is easily generated on the image,
There is a problem that the sharpness of the image is deteriorated, and the scattering of toner from the developing device into the image forming device is deteriorated. It is known that this is because the physical properties of the recycled toner, such as fluidity, chargeability, transferability, and cleaning properties, are deteriorated as compared with the new toner.

[0003] Irrespective of the presence or absence of a toner recycling mechanism, even when the particle size of the toner is reduced for the purpose of improving image quality, the fluidity of the toner is reduced. When the fluidity of the toner changes,
The fluidity of a developer comprising a toner and a carrier (the term "developer" is used herein to mean "two-component developer") also changes. Generally, the flowability of the developer is prevented by improving the flowability of the toner by externally adding fine particles such as silica as an additive to the toner surface. However, the fluidity of the developer may change depending on the copy conditions. For example, when a low-area-ratio original is continuously copied, the toner in the developer is less consumed, the toner is not replaced, and the stirring in the developing device is performed for a long time, and the silica on the toner surface is buried in the toner. Therefore, depending on the toner, the fluidity is deteriorated, and therefore, the fluidity of the developer is also deteriorated. Further, the fluidity of the developer greatly changes depending on the ratio of the recycled toner to the toner in the developer (see FIG. 12). This is because, in the recycled toner, silica on the surface of the toner is buried in the toner, so that the fluidity of the toner is deteriorated and the fluidity of the developer may be deteriorated.

In the case where a two-component developer is used, if the fluidity of the developer in the developing device deteriorates, problems such as uneven density and blurred horizontal lines may occur (see FIG. 13). ). In addition, since the stirring in the developing device becomes worse, a difference in image density may occur in the axial direction.

As means for solving the above problems, particularly the problem of the fluidity of the developer when a recycled toner is used, the following has been proposed. For example,
Japanese Patent Application Laid-Open No. HEI 6-19312 discloses that a cleaning device that collects residual toner on a surface of an image carrier after transfer, a collection toner storage device provided separately from an unused toner storage device in a developing unit, and a collection device that collects the collected toner. A conveying unit that conveys the collected toner to the developing unit, a conveying unit that conveys the collected toner to the developing unit, and a conveying unit that supplies the unused toner from the unused toner storing unit to the developing unit. Controlling the unused toner replenishing device and the recovered toner replenishing device to reduce the ratio of the amount of collected toner to the total amount of toner in the developing means to a predetermined value or less in the image forming apparatus having the used toner replenishing device. An image forming apparatus characterized by providing means "has been proposed. JP 7
JP-A-92873 discloses that "a latent image formed on a latent image carrier is visualized as a toner image by a developing device, the toner image is transferred to a transfer material, and the toner image remains on the latent image carrier after the transfer. In an image forming method in which toner is removed from a latent image carrier by a cleaning device and collected, only when the amount of toner used in a developing device within a specified period is equal to or greater than a reference amount, the toner is collected by the cleaning device within that period An image forming method characterized by supplying the used toner to the developing device and reusing the toner, has been proposed. JP-A-7-7
No. 2690 states, “An electrostatic latent image is formed in an image forming area on the surface of a photoreceptor, the electrostatic latent image is visualized as a toner image by a developing device, and the toner image is transferred onto a recording medium.
After the transfer, the untransferred toner remaining on the photoreceptor surface is removed by a cleaning device, and the removed untransferred toner is returned to the developing device. To remove the toner of the toner recycle image pattern by the cleaning device in a state where the image pattern is formed, and return the removed toner to the developing device. ,
An image forming method characterized in that, in order to adjust the quantitative ratio between the returned toner and the untransferred toner, the conditions for forming the toner recycling image pattern are changed in accordance with the image area of the document. Has been proposed. JP 7
Japanese Patent Application No. -230208 describes "a means for collecting a developer after image formation in an image forming apparatus for forming an image using a developer, and a collected developer supply means for storing and supplying the collected developer." A new developer supply means for storing and supplying the new developer, a mixed developer supply means for mixing and supplying the supplied recovered developer and the new developer, and detecting an apparatus environment Environment detecting means, a mixing table in which a mixing ratio of the collected developer and the new developer to the apparatus environment is set, and a mixing ratio of the collected developer and the new developer according to the detection result of the environment detecting means. An image forming apparatus comprising a control unit for controlling the collected developer supply unit and the new developer supply unit so as to change based on the mixing table. The basic idea of the prior art cited as an example is to prevent the deterioration of the image quality and the like due to the deteriorated recycled toner by controlling the mixing ratio of the recycled toner and the new toner. Based on this basic idea, Japanese Patent Laid-Open Publication No.
No. 91, "In a developer supply device for mixing and supplying a plurality of types of developers, a first supply unit for supplying a first developer and a second supply unit for supplying a second developer Supply means, mixing means for mixing the developer supplied from the first supply means and the second supply means, and variable means for changing the mixing ratio of the first developer and the second developer And a developer supply device characterized by having the following. In the developer supply device proposed here, the mixing ratio of the collected developer and the new developer is controlled in the same manner as described above, but at this time, attention is also paid to the amount of the additive in the developer, Even if the physical properties of the recycled toner change, the mixing ratio between the new toner and the recycled toner is changed by changing the mixing ratio according to the change in the physical properties so that the additive amount in the mixed developer is within the specified range. Control.

However, in the above-described method for controlling the mixing ratio of the new toner and the recycled toner, a container for storing the recycled toner is required, and the machine becomes large. In addition, when the amount of recycled toner increases due to environmental fluctuations or the like, there is a disadvantage that the amount of unused recycled toner only increases.

Japanese Patent Application Laid-Open No. 5-31354 discloses a method for mixing an additive to improve the flowability of a recycled toner.
In No. 5, "the cleaning device for removing the residual toner after the transfer on the surface of the image carrier, the collected toner storage device provided separately from the unused toner storage device in the developing device, and the collected toner removed by the cleaning device And a collected toner supply device that supplies the collected toner from the collected toner storage device to the developing device, and a collected toner supply device that supplies the collected toner from the unused toner storage device to the developing device. In an image forming apparatus having an unused toner replenishing device for replenishing unused toner, an additive is added to the collected toner in the collected toner accommodating device before replenishing the collected toner into the developing device. An image forming apparatus characterized by providing a mixing means "has been proposed.
The proposed image forming apparatus improves the fluidity of the recycled toner by mixing an additive before replenishing the recycled toner into the developing device in a machine having a toner recycling mechanism, thereby improving the quality of the image. The purpose is to get. However, in this method, an additive is mixed regardless of the fluidity of the developer, so that it is not guaranteed to appropriately control the fluidity of the developer. Also, it is unavoidable to increase the size of the machine for the same reason as described above.

[0008] As described above, an apparatus which attempts to ensure appropriate fluidity of a developer by changing a mixing ratio of a recycled toner and a new toner or by adding an additive to a recycled toner is known as an apparatus. It is difficult to reduce the size.
Further, in the case of an apparatus having no toner recycling mechanism, that is, deterioration of the fluidity of the developer caused when the recycled toner is not used, and even when the toner is recycled, the fluctuation of the environment caused by the fluctuation of the environment and the copy condition, etc. It is also difficult to respond to the deterioration of liquidity.

As a control means for replenishing the toner to the developing device, the toner density of the developer in the developing device (the ratio of the toner in the developer) in the developing device is determined based on the detection result of the toner adhesion amount of the toner image of the reference density pattern. Although such control is performed, when such control is performed, even when the toner in the developer is all new toner, an additive (eg, silica) is excessively replenished in the developer when the toner concentration increases. There is a problem.

[0010]

In view of the above problems, the present invention relates to an environment (temperature, humidity), copy conditions (image area ratio of an original), changes in recycled toner (fluidity of recycled toner, recycled toner, etc.). The first problem is to solve various problems associated with changes in the fluidity of the two-component developer due to fluctuations in the ratio of the two-component developer. It is a second object of the present invention to be able to always detect a change in the fluidity of the developer with high accuracy so that the above problem can be effectively solved.
It is a third object of the present invention to avoid the above-mentioned inconvenience by maintaining an appropriate fluidity by adding an additive even if toner concentration changes.

[0011]

The first object of the present invention is to provide an image forming apparatus having a developing device for developing an electrostatic latent image formed on an image carrier with a two-component developer according to the present invention. It has a detecting means for detecting the fluidity of the developer in the developing device, and an additive charging means for charging an additive into the developing device based on a detection result by the detecting means. Is solved by the image forming apparatus described above. The detecting means may be a torque sensor for detecting a torque of a developer stirring shaft for stirring the developer in the developing device.

A detecting means for detecting and storing a time required for the developer to move in a predetermined section after the developing device starts moving (for example, a predetermined detecting position of a developer circulation path in the developing device); Means for detecting and storing a time required for the developer to move in a predetermined section from the start of movement of the developing device to the detection position by using a sensor for detecting the presence or absence of the developer provided in the developing device), or It is also advantageous that the detecting means has a sensor (for example, a pressure sensor) for detecting the bulk density of the developer in the developing device to solve the second problem. This is because the stirring torque of the developer stirring shaft measured by the torque sensor is not only the resistance of the developer but also the mechanical elements such as the resistance of the agitating part of the developing device, the shape and weight of the stirring member, and the parts of the stirring part. It is affected by abrasion, toner accumulation in the developing device, etc., and particularly in a large developing device, the ratio of the contribution of the resistance of the developer to the stirring torque is reduced. This is because a small change in fluidity, which is difficult to detect with a torque sensor, can be accurately detected.

A toner density sensor for detecting the ratio (toner density) of the toner in the developer is provided, and the additive input means further takes into account the toner density detected by the toner density sensor. It is advantageous to control the dosing of the additives into the developing device. This also solves the third problem.
At this time, based on the fluidity of the developer containing no recycled toner when the toner concentration is the same as the detected toner concentration, the amount of the additive added is controlled by measuring the current fluidity of the developer in the developing device. Thereby, for example, when the toner concentration of the developer in the developing device is controlled to be higher,
Even if the toner in the developer is only a new toner, the additive is added and the excess additive adheres to the photoreceptor to cause troubles such as black stripes, and the toner concentration of the developer in the developing device When the toner is controlled to be lower, it is possible to prevent the unevenness of the solid portion density and the horizontal line blurring from being improved without adding the additive even if the toner in the developer is insufficient.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the embodiment shown in the drawings, the present invention is applied to an electrophotographic copying machine (hereinafter, simply referred to as "copying machine").

FIG. 1 is a schematic configuration diagram of a main part of a copying machine according to one embodiment of the present invention. The photosensitive drum 1 rotating in the direction of the arrow a is electrostatically charged in advance by corona discharge from the charging charger 2, and the charged surface is irradiated with optical image information of document reflected light to form an electrostatic latent image. To form Subsequently, the electrostatic latent image is visualized by applying toner from a developing device 3 as a developing unit that develops with a two-component developer composed of toner and carrier, and then supplied in the direction of arrow b. The visible image is transferred by the transfer charger 4 onto a recording sheet to be printed. After the transfer, the recording paper is separated from the photosensitive drum 1 by the separation charger 5, and is conveyed to a fixing device (not shown) to perform fixing.

The replenishment of toner from the toner hopper 6 to the developing device 3 is performed by rotating the toner replenishing device 6a. The control of the toner replenishment amount and the replenishment timing is based on the output signal of the optical sensor 7 which detects the toner adhesion amount of the toner image of the reference density pattern formed on the non-image forming area on the photosensitive drum 1. This is performed by controlling the driving time of the toner supply device 6a as a means.

The developing device is driven by a developing device drive motor (not shown) attached to the copying machine main body. The developing device drive motor and the developer stirring shaft 8 are coupled by a coupling via a torque sensor 9. In the present embodiment, the fluidity of the developer is determined based on the detection result of the torque sensor 9.

In the present embodiment and the embodiments described later, silica is considered as an additive to be added to the developer. This silica is contained in a silica hopper 10. FIG. 2 shows the structure of the silica hopper 10. The silica contained in the silica hopper 10 is clogged between the sponge 10b and the grooving roller as the supply roller 10a, and is supplied into the developing device 3 according to the rotation of the supply roller 10a. The supply amount of silica can be controlled by the rotation time of the roller 10a.

FIG. 3 is a flowchart showing the flow of the operation of the present embodiment (the torque of the developer stirring shaft 8 is detected every 500 sheets of image formation). For the detection of the torque, the developer stirring shaft 8 is rotated ten times, and the output of the torque sensor 9 is detected 100 times at intervals of 10 msec during the rotation, and the average value is defined as the developer stirring shaft torque T. At this time, if the flowability of the developer deteriorates due to an increase in the ratio of recycled toner in the developer, burial of silica on the toner surface, or environmental fluctuation,
The resistance when stirring the developer increases, and the torque T of the developer stirring shaft 8 increases. Therefore, it can be considered that when the torque T of the developer stirring shaft 8 increases, the fluidity of the developer deteriorates. In the present embodiment, when the detection result of the torque sensor 9 becomes larger than 4.4 kgf · cm, silica is supplied from the silica hopper 10 into the developing device 3 in order to improve the fluidity. The silica is supplied to the developing device 3 by rotating a silica supply motor (not shown) for 3 seconds.
(0.1 g). After the replenishment, the developer stirring shaft 8 is rotated 30 times to sufficiently mix the silica and the developer, and then the developer stirring shaft torque T is detected again. The above operation
It is continued until the detection result of the torque T becomes T <4.4 kgf / cm.

FIG. 4 is a schematic diagram of a main part of a copying machine according to another embodiment of the present invention. The same members as in FIG.
The same reference numerals are given. Hereinafter, portions different from the above-described embodiment will be described. The copying machine shown in FIG. 4 includes a toner concentration sensor 11 for detecting the toner concentration in the developer in the developing device. Further, the ROM 12 stores the developer stirring shaft torque Tref for each toner concentration TC of the developer when the toner in the developer is all new toner.
(Hereinafter, referred to as “reference torque”) (Table 1) is stored.

[0021]

[Table 1]

FIG. 5 is a flowchart showing a flow of the operation in the embodiment shown in FIG. An operation mainly different from that of the above-described embodiment will be described below. While the developing device drive motor is operating, first, the toner concentration sensor 11 detects the toner concentration TC1 of the developer in the developing device. A reference torque Tref1 corresponding to the detected toner concentration TC1 is determined based on a table stored in the ROM 12. Torque sensor 9
When the developer stirring shaft torque T actually detected is larger than the reference torque Tref1, it is considered that the fluidity of the developer has deteriorated. In this embodiment, when T-Tref1> 0.4 kgf.cm, silica is supplied from the silica hopper 10 into the developing device 3 to improve the fluidity. Silica is supplied into the developing device 3 by rotating the silica supply motor for 3 seconds (0.1 g). After the replenishment, the developer stirring shaft 8 is rotated 30 times to sufficiently mix the silica and the developer, and then the torque T of the developer stirring shaft is detected again. The above operation is continued until the detection result of the torque T becomes T-Tref1 <0.4 kgf / cm.

FIG. 6 is a schematic configuration diagram of a main part of a copying machine according to another embodiment of the present invention. The same members as those in the above-described embodiment are denoted by the same reference numerals. Hereinafter, portions different from the above-described embodiment will be described.

During the operation of the developing device, the developer circulates through the developing device, and a part of the developer passes through a developer recirculation path 3d (hereinafter, referred to as a "separator") located above the developing device. As shown by thick arrows in FIGS. 7A and 7B, the flow returns to the lower portion of the developing device. When the developing device is not moving, the developer does not reflux. In this state,
The region where the developer is present is determined, and the separator 3d
There is no developer on top. The copying machine shown in FIG. 6 includes a sensor 13 (for example, a reflection type optical sensor) for detecting the presence or absence of the developer on the separator 3d. Since the region where the developer exists while the driving of the developing device is stopped is determined, the time from when the stirring shaft of the developing device starts to move until the developer is detected at the predetermined detection position A on the separator 3d. By measuring (hereinafter referred to as “recirculation start time”), the time required for the developer to move in a predetermined section, that is, the fluidity of the developer can be evaluated.
The measured reflux start time is stored in the RAM 14.
The ROM 12 stores, for each toner concentration TC of the developer, a table (Table 2) of a recirculation start time tref (hereinafter, referred to as “reference recirculation start time”) when the toner in the developer is all new toner. Have been.

[0025]

[Table 2]

FIG. 8 shows a flow chart of the operation in the present embodiment (the developer recirculation start time is measured every 500 sheets of image formation). First, the toner density TC1 is detected by the toner density sensor 11 while the developing device is operating. The reference recirculation start time tref1 at the toner concentration TC1 is determined using a table in the ROM 12. After that, after stopping the developing device for 5 seconds (that is, after stopping the developing device driving motor (not shown) for driving the developer stirring shaft 8 for 5 seconds), the developing device is started again to start the developer recirculation start time t. Is measured. At this time, if the flowability of the developer is deteriorated due to an increase in the ratio of the recycled toner in the developer, burial of silica on the toner surface, or environmental fluctuation, the resistance when the developer passes over the separator 3d increases. The time (recirculation start time t) required for the developer to reach the detection position A in the downstream portion of the separator after the restart of the developing device is increased. Therefore,
When the reflux start time t is delayed, it can be considered that the fluidity of the developer has deteriorated. In particular, in the present embodiment, it is considered that the fluidity of the developer is deteriorated when the actually detected reflux start time t is longer than the determined tref1, and when t−tref1> 0.5 sec, the fluidity is improved. The silica is supplied from the silica hopper 10 into the developing device 3. Thus, when the silica is introduced, a change in fluidity due to the toner concentration can be taken into consideration. After replenishing the silica, the developer agitating shaft 8 is rotated 30 times to sufficiently mix the silica and the developer, and then the reflux start time is detected again. The above operation is continued until the torque detection result becomes t-tref1 <0.5 sec.

FIG. 9 is a schematic structural view of a main part of a copying machine according to another embodiment of the present invention. The same members as those in the above-described embodiment are denoted by the same reference numerals. Hereinafter, portions different from the above-described embodiment will be described. The copying machine shown in FIG. 9 is provided with a sensor 15 (a pressure sensor in this embodiment) for detecting the bulk density of the developer in the developing device below the developer stirring paddle 3e. As shown in FIG. 10, as the developer fluidity deteriorates, the bulk density decreases. When the bulk density decreases, the developer pressure under the developer stirring paddle 3e decreases, so that the bulk density is detected from the output of the pressure sensor 15. The ROM 12 stores, for each toner concentration TC, a table (Table 3) of the bulk density Pref of the developer when the toner in the developer is all new toner (hereinafter referred to as “reference bulk density”). .

[0028]

[Table 3]

FIG. 11 is a flowchart showing the flow of operation in the case of the embodiment shown in FIG.
The pressure sensor 15 detects the bulk density pressure of the developer below the developer stirring screw (developer stirring paddle) 3e in the developing device for every 00 sheets. First, while the developing device is operating, the toner density TC1 is detected by the toner density sensor 11.
Is detected. The reference bulk density Pref1 of the developer at the toner concentration TC1 is determined using a table in the ROM 12. Thereafter, the bulk density P of the developer is measured. At this time, if the flowability of the developer is deteriorated due to an increase in the ratio of the recycled toner in the developer, burying of silica on the toner surface, or environmental fluctuation, the bulk density of the developer is reduced,
The pressure detected by the pressure sensor 15 below the developer stirring screw becomes smaller. Therefore, when the detected developer pressure is reduced, the bulk density is reduced, that is, it is considered that the fluidity of the developer is deteriorated.
The silica is supplied from the silica hopper 10 into the developing device 3. In order to take into account the change in fluidity due to toner concentration, the bulk density P of the developer actually detected is equal to the reference bulk density P.
It is convenient to consider that the flowability of the developer has deteriorated when it is smaller than ref1. In this embodiment, when Pref1-P> 0.1, silica is supplied from the silica hopper 10 into the developing device 3 to improve the fluidity. After the silica is replenished, the developer stirring shaft 8 is rotated 30 times to sufficiently mix the silica and the developer, and then the developer bulk density P is detected again. The above operation is continued until the detection result of the developer bulk density P becomes Pref1-P <0.1.

[0030]

The image forming apparatus according to any one of claims 1 to 4,
Since it has a detecting means for detecting the fluidity of the developer in the developing device and an additive charging means for adding an additive to the developer in the developing device based on the detection result by the detecting means, the fluidity of the developer is reduced. It is possible to detect at any time and to add the additive based on the detection result, and accordingly, it is possible to appropriately control the fluidity of the developer.
High-quality images can be maintained irrespective of variations in humidity), copy conditions (image area ratio of original), changes in recycled toner (fluidity of recycled toner, ratio of recycled toner). Further, the image forming apparatus can be used regardless of the presence or absence of the toner recycling mechanism. FIG. 14 shows the effect of the silica re-addition on the fluidity of the developer. In the image forming apparatus according to the third aspect, since the fluidity of the developer is evaluated by means for detecting and storing a time required for the developer to move in a predetermined section after the developing device starts to move, the torque sensor detects the time. It is possible to accurately detect a change in fluidity that is difficult. In the image forming apparatus according to claim 4, since the fluidity of the developer is detected by detecting the bulk density of the developer by, for example, a pressure sensor that measures the pressure of the developer at the time of stirring the developer. It is possible to accurately detect the fluidity of the developer over a long period of time irrespective of a change in the stirring shaft torque due to toner accumulation in the inside, abrasion of parts of the stirring unit, and the like.

In the image forming apparatus according to the present invention, a toner density sensor for detecting a ratio (toner density) of the toner in the developer is provided. The additive introduction means controls the amount of the additive introduced into the developing device based on the detection result of the fluidity, so that the additive can be added without excess and deficiency, and the toner concentration in the developing device can be increased. In the case of controlling, even when the toner in the developer is a new toner, an excessive amount of an additive is added to cause a problem such as a black stripe,
In the case where the toner concentration in the developer is controlled to be low, there is no possibility that the additive is not added and a problem such as unevenness of solid portion density and improvement of horizontal line blur is not caused. In the image forming apparatus according to the sixth aspect, the additive introduction unit may detect the amount of the fluidity detected by the detection unit (for example, a developer stirring shaft torque, a reflux start time,
And the corresponding reference amount (reference torque, reference reflux start time, reference bulk density, etc.) of the fluidity stored in advance with respect to the toner density detected by the toner density sensor. Since the amount of additive added is controlled based on the result of comparison with the above, the effect of the image forming apparatus according to claim 5 can be further enhanced.

Further, since the image forming apparatus according to the present invention does not control the fluidity by controlling the mixing ratio of the recycled toner and the new toner, the image forming apparatus includes a space for storing the collected toner. There is no necessity, and thus the above-mentioned effects can be exhibited without increasing the size of the device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part of a copying machine according to one embodiment of the present invention.

FIG. 2 is a view showing the structure of a silica hopper containing silica as an additive to a developer.

FIG. 3 is a flowchart showing a flow of an operation in the embodiment shown in FIG.

FIG. 4 is a schematic configuration diagram of a main part of a copying machine according to another embodiment of the present invention.

5 is a flowchart showing a flow of an operation in the embodiment shown in FIG.

FIG. 6 is a schematic configuration diagram of a main part of a copying machine according to another embodiment of the present invention.

7A is a schematic view of the inside of the developing device of the copying machine shown in FIG. 6 as viewed from above, and FIG. 7B is a schematic diagram of the developing device portion viewed from the side.

FIG. 8 is a flowchart showing a flow of an operation in the embodiment shown in FIG.

FIG. 9 is a schematic configuration diagram of a main part of a copying machine according to another embodiment of the present invention.

FIG. 10 is a graph showing the relationship between the fluidity and bulk density of a developer.

FIG. 11 is a flowchart showing a flow of an operation in the embodiment shown in FIG. 9;

FIG. 12 is a graph showing the relationship between the ratio of recycled toner and the fluidity of developer. 50g fluidity is JI
It measured using the S-Z2502 rheometer.

FIG. 13 is a graph showing the relationship between the fluidity of the developer and the image quality.

FIG. 14 is a diagram showing the effect of re-adding silica on the fluidity of a developer.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor drum 2 charging charger 3 developing device 3a fin 3b sleeve 3c screw 3d separator 3e developer stirring paddle 4 transfer charger 5 separation charger 6 toner hopper 6a toner replenishing device 7 optical sensor 8 developer stirring shaft 9 torque sensor 10 silica hopper 10a Grooving roller 11 Toner density sensor 12 ROM 13 Reflective optical sensor 14 RAM 15 Pressure sensor

Claims (6)

[Claims] 1. An image forming apparatus having a developing device for developing an electrostatic latent image formed on an image carrier with a two-component developer, wherein detection of the fluidity of the developer in the developing device is performed. An image forming apparatus comprising: an adding unit configured to input an additive into the developing device based on a detection result of the detecting unit. 2. The image forming apparatus according to claim 1, wherein the detecting unit is a torque sensor that detects a torque of a developer stirring shaft for stirring the developer in the developing device. apparatus. 3. The apparatus according to claim 1, wherein said detecting means has means for detecting and storing a time required for the developer to move in a predetermined section after the developing device starts moving. Image forming device. 4. The image forming apparatus according to claim 1, wherein the detection unit is a sensor that detects a bulk density of the developer in the developing device. 5. A toner density sensor for detecting a ratio of the toner in the developer,
5. The method according to claim 1, wherein said additive introduction means further controls an introduction amount of the additive into said developing device in consideration of a ratio of the toner detected by said toner concentration sensor. The image forming apparatus according to claim 1. 6. The method according to claim 1, wherein the additive input means includes a detection amount detected by the detection means and a reference amount of fluidity stored in advance with respect to a ratio of the toner detected by the toner density sensor. The image forming apparatus according to claim 5, wherein the amount of the additive to be added is controlled based on the comparison result.