JPH0980894A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply developer to a developer basin when the amount of developer in the developer basin in the casing of a developing device is a predetermined amount or less in order to prevent the deterioration of image quality with time of developer in a one-component system image forming device. SOLUTION: In the case the amount of developer in the developer basin 17 detected by a sensor 17 provided on a partition member 16 is a predetermined amount or less agitators 12 and 13 are rotated to supply developer to the developer basin 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer.
The present invention relates to prevention of deterioration in image quality due to deterioration with time of a developer in an image forming apparatus that forms an image by developing a latent image formed on the surface of a latent image carrier using a one-component developing device.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus of this type, there is one that forms an image by developing a latent image formed on the surface of a latent image carrier with, for example, a frictionally charged one-component developer. Are known.

[0003]

However, according to the image forming apparatus, there is a problem that the quality of the image formed is deteriorated when the image formation is repeated. As a result of research conducted by the inventors, it has become clear that the cause of this problem is due to deterioration of the developer over time. That is, in an image forming apparatus that uses a one-component developer as a developer, a load is applied to the developer as the developer is conveyed through the developing device, and the developer is likely to deteriorate. Cause deterioration of image quality. Specifically, as shown in FIG. 10, when the number of image formed sheets increases, the cohesion of the developer increases and the image density decreases. In this case, as for the reduction of the image density, it is possible to appropriately replenish the developer to secure the image density as shown in the figure, but it is inevitable that the image quality of the image formed before the replenishment is deteriorated.

The present invention has been made in view of the above problems, and an object of the present invention is to prevent deterioration of image quality due to deterioration of a developer with time and to form an excellent image. To provide a forming apparatus.

[0005]

In order to achieve the above object, an image forming apparatus according to a first aspect of the invention is an image forming apparatus for developing a latent image formed on a latent image carrier by a developing device to form an image. In the developing device, a casing portion in which a developer is held, and a developer carrier for developing the latent image by supplying the developer carried on the surface to the latent image carrier. A developer reservoir provided in the casing portion and having the developer carrier therein, and a developer supply that conveys the developer in the casing portion and supplies the developer to the developer reservoir portion Means, a developer amount detection sensor for detecting the amount of developer in the developer reservoir, and the developer amount sensor detects that the amount of developer in the developer reservoir is less than or equal to a predetermined amount. And driving the developer supply unit to Is characterized in that a one-component developing device and a developer supply control means for supplying the developer to the image agent reservoir.

In the image forming apparatus according to claim 1,
The developer amount detection sensor detects that the amount of developer in the developer reservoir is below a predetermined amount, and supplies the developer only when the developer carrier does not supply sufficient developer. The means is driven to carry the developer and supply the developer to the developer reservoir. Therefore, even in cases other than the above, the load applied to the developer is lighter than that in the case where the developer supply unit is driven, and deterioration of the developer is suppressed. In addition, since the developer is sequentially used for image formation from that supplied to the developer reservoir, the developer loaded by transportation remains in the casing without being used, and is further subjected to frictional electrification treatment and the like. As a result, the deterioration of the developer is prevented.

An image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect, characterized in that it has a developer stirring means for stirring the developer in the developer reservoir.

In the image forming apparatus according to claim 2,
The developer is agitated by the agitating means in the developer reservoir,
Even if the developer is in a solidified state with a high degree of aggregation, the developer will be loosened. Therefore, the developer is not supplied to the latent image carrier through the developer carrier in a solid state and is not used for image formation. Further, such a stirring member is provided in the vicinity of the detection surface of the developer amount detection sensor, the stirring member is formed of a material that does not damage the flexible detection surface, and the detection surface is rubbed. According to the cleaning configuration described above, it is possible to prevent erroneous detection of the developer amount of the developer amount detection sensor due to the developer adhering to the detection surface.

An image forming apparatus according to a third aspect of the present invention is an image forming apparatus that develops a latent image formed on a latent image carrier by a developing device to form an image, the developing device including a developer inside thereof. A casing portion that holds the latent image bearing member, a developer bearing member that supplies the developer carried on the surface to the latent image bearing member to develop the latent image, and the developing unit provided inside the casing unit. A developer reservoir provided with a developer carrier, and a developer supply means for conveying the developer in the casing to supply the developer to the developer reservoir, the developer being supplied into the casing. One-component image forming apparatus in which the developer supply capability of the developer supply unit is set so that the change in the cohesion degree of the developer from the time when the developer is supplied to the next time is 10% or less. Is characterized by Than it is.

In the image forming apparatus according to claim 3,
The developer supply capability of the developer supply unit that supplies the developer to the developer reservoir is such that the change in the degree of aggregation of the developer from the supply of the developer to the next supply of the developer is 1
It is set to be 0% or less.

An image forming apparatus according to a fourth aspect is an image forming apparatus that develops a latent image formed on a latent image carrier by a developing device to form an image, and the developing device has a developer inside thereof. A casing portion that holds the latent image bearing member, a developer bearing member that supplies the developer carried on the surface to the latent image bearing member to develop the latent image, and the developing unit provided inside the casing unit. A developer reservoir portion provided with a developer carrier, a developer supply means for transporting the developer in the casing portion and supplying the developer to the developer reservoir portion, and a latent image formed on the latent image carrier. When the latent image amount integrating means for integrating the amount of the latent image and the latent image amount integrated by the latent image integrating means become a predetermined amount or more, the developer supplying means is driven to develop in the developer reservoir. One-component system including developer supply control means for supplying a developer It is characterized in that an image device.

According to the image forming apparatus of claim 4,
The amount of the latent image formed on the latent image carrier accumulated by the latent image amount accumulating means becomes a predetermined amount or more, and the amount of the developer in the developer reservoir decreases, so that the amount of the latent image carrier is sufficient for the developer carrier. Only when the developer is not supplied, the developer conveyed in the casing is supplied to the developer reservoir. Therefore, even in a case other than the above case, the load applied to the developer is reduced as compared with the case where the developer is supplied to the developer reservoir, and the deterioration of the developer is suppressed. Further, it is possible to prevent the image density from being lowered due to lack of the developer in the developer reservoir.

An image forming apparatus according to a fifth aspect is an image forming apparatus which develops a latent image formed on a latent image carrier by a developing device to form a visible image to form an image. The developing device is provided with a density detection sensor that detects the density of the visible image formed on the body, and the developing device supplies the latent image bearing member with the casing part in which the developer is held and the developer carried on the surface. Then, a developer carrier for developing the latent image, a developer reservoir portion provided inside the casing portion, the developer reservoir portion having the developer carrier therein, and carrying the developer in the casing portion. When the cumulative value of the density detected by the density detection sensor and the developer supply means for supplying the developer to the developer pool portion becomes a predetermined value or more, the developer supply means is driven to drive the developer. Supply developer to the reservoir Is characterized in that a one-component developing device provided with an image agent supply control means.

According to the image forming apparatus of claim 5,
The developer is supplied to the developer reservoir only when the integrated value of the densities of the visible images formed on the latent image carrier detected by the density detection sensor is equal to or higher than a predetermined density. Therefore,
Even in cases other than the above, the load applied to the developer is reduced and deterioration of the developer is suppressed as compared with the case where the developer is supplied to the developer reservoir. Further, it is possible to prevent the image density from being lowered due to lack of the developer in the developer reservoir.

An image forming apparatus according to a sixth aspect of the present invention is the image forming apparatus according to the first to fifth aspects, wherein the volume of the developer reservoir is the maximum amount of development used in one image forming operation. It is characterized by being larger than the volume of the agent.

In the image forming apparatus according to claim 6,
For example, even when an image is formed using a large amount of developer such as an image containing many solid portions, the volume of the developer pool is the maximum amount of development used in one image forming operation. Since it is larger than the volume of the developer, the amount of the developer does not become insufficient when forming the image. (Hereinafter, margin)

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] A first embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine) which is an image forming apparatus will be described below. FIG. 1 is a schematic configuration diagram of a copying machine according to the present embodiment. In this copying machine, an electrostatic latent image is formed on the surface of the photosensitive drum 1 as a latent image carrier by an optical system as a latent image forming means (not shown). Then, the electrostatic latent image is developed by an image device using toner as a developer to form a toner image as a visible image. Then, this toner image is transferred to a recording paper as a recording material by a transfer device (not shown) such as a corona discharger, and a toner image is formed on the surface of the recording paper.

In this copying machine, the developing device is a one-component developing device for forming an image by causing charged toner to fly to the photosensitive drum 1 by the force of an electric field. The developing device will be described below. This developing device
A developing roller 10 as a developer bearing member in a state where a minute gap is maintained with the photosensitive drum 1, a supply roller 11 whose surface is made of sponge and is attached in contact with the developing roller 10, and agitates and conveys toner. Agitators 12, 13 and a blade 14 for forming a thin layer of toner on the surface of the developing roller 10 are provided, and these are mounted in a casing 15. The blade 1
Reference numerals 2 and 13 function as the developer supplying means described in the claims.

In the above structure, the toner in the casing 15 is conveyed to the supply roller 11 while being agitated by the agitators 12, 13 and the toner is charged by the rubbing between the supply roller 11 and the developing roller 10, and this charging is performed. The formed toner adheres to the surface of the developing roller 10. Then, the charged toner is thinned by the blade 14 and then conveyed to a position close to the photosensitive drum 1 by the rotation of the developing roller 10 in the direction of the arrow in the figure, and the electrostatic latent image formed on the surface of the roller. Used for image development.

Further, a plate-shaped warp member 16 is attached to the developing device, and by this member, the inside of the casing 15 is a developer reservoir 17 (hereinafter, referred to as an area where the developing roller 10 is provided). It is divided into two regions, a region 17) and a region 18 having agitators 12, 13 therein. The height of the vertical member 16 is preferably higher than the center of rotation of the supply roller 11, and in the illustrated example, the height is substantially equal to the height of the uppermost portion of the supply roller 11. As shown in an enlarged view of a part of this copying machine, a sensor 19 as a developer amount detecting sensor is attached to the vertical member 16 so that its detecting surface 19a faces the area 17 side. ing.

In the above structure, the agitators 12, 13 as the supply means for supplying the toner to the area 17 are judged by the sensor 19 that the amount of the toner in the area 17 is smaller than the predetermined amount of toner. In such a case, it is controlled by a control means (not shown) such as a microprocessor so as to rotate and drive. As a result, even when the amount of toner in the area 17 is insufficient,
Compared with the case where the agitators 12 and 13 are driven to rotate,
The load applied to the toner by the time it is used for development is reduced, and the toner is less likely to deteriorate. Further, the toner is sequentially used for the development from the one conveyed to the area 17, so that the toner applied with a load due to the conveyance or the like does not stay in the casing 15 for a long time.

Further, in this copying machine, a mini-agitator 20 may be provided as a developer stirring means for stirring the toner conveyed to the area 17. Mini agitator 20
By providing, even if the toner is conveyed to the area 17 in a solid state, the mini agitator 20 is rotated so that the toner is loosened. Regarding the timing of rotating the mini agitator 20,
Similar to the agitators 12 and 13, the sensor 19 may be rotationally driven when it is determined that the amount of toner in the area 17 is smaller than a predetermined amount of toner.

Further, if the mini-agitator 20 is formed of a material that does not damage the detection surface 19a of the flexible sensor 19, and is provided at a position where the detection surface is rubbed,
Since the detection surface 19a is cleaned, it becomes possible to prevent the toner from adhering to the detection surface 19a.

[Second Embodiment] A second embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine) which is an image forming apparatus will be described below. FIG. 3 is a schematic configuration diagram of the copying machine according to the present embodiment. In addition, about the structure similar to 1st Embodiment, only the same code | symbol as shown in FIG. 1 which shows this embodiment in FIG. 3 is attached | subjected, and the description is abbreviate | omitted.

In the copying machine according to the first embodiment,
A developer pool 17 (hereinafter referred to as a region 17) is attached to the vertical member 16.
A sensor 19 for detecting the amount of toner inside the agitator, and the agitators 12 and 13 as the developer supplying means are driven at a predetermined timing by using the sensor. Is not provided and the agitators 12 and 13 are always driven when the developing device is being driven.

Here, it is desirable that the amount of toner supplied to the area 17 by the agitators 12 and 13 is as small as possible. This is because when the amount of toner supplied to the area 17 is excessive, toner that is not used for developing the electrostatic latent image stays in the area 17, and the stayed toner is accumulated between the developing roller 10 and the supply roller 11. This is because the toner is repeatedly frictionally charged by the rubbing, and the degree of cohesion increases and the quality of the formed image deteriorates. If so, it seems desirable to reduce the amount of toner supplied to the area 17 sufficiently so that the toner cohesion does not change. On the other hand, on the other hand, when only the toner that does not change the toner aggregation is supplied to the area 17, the amount of toner in the area is insufficient and the toner does not sufficiently follow the photosensitive drum 1 and is supplied to the drum. There is also a case where the image quality deteriorates due to the shortage of the amount of toner that is retained.

Therefore, in this copying machine, the agitator 12 is used.
And 13 are constantly driven when the developing device is being driven, the amount of toner supplied to the area 17 is adjusted to reduce the image quality due to an increase in the degree of toner aggregation and the toner supplied. It aims to solve both the deterioration of image quality due to the lack of. Hereinafter, a specific description will be given.

As a result of research conducted by the inventors, image defects caused by high toner cohesion are limited to the extent that deterioration of image quality is not a problem if the change is within a certain range. It has been clarified that the deterioration of the image quality can be prevented when the change in the toner cohesion is 10% or less, preferably 5% or less. In this copying machine, the rotation speed of the agitators 12 and 13 is adjusted to set the toner replenishing ability to the area 17 of the agitator to a desired value in order to keep the increase in the cohesion degree within the relevant value. There is. That is, in the conventional case, the rotation speed of the agitators 12 and 13 is 1
Although it is about 20 rpm, this causes the amount of toner supplied to the region 17 to become excessive, and the change in the degree of aggregation in the region becomes 10% or more. Therefore, in this apparatus, the rotation speed of the agitators 12 and 13 is set to 10 rpm or less, the amount of toner supplied to the region 17 is sufficiently reduced, and the change in the degree of aggregation is set to 10% or less.

Further, in the copying machine according to the first embodiment, the height h of the vertical member 16 is substantially equal to the height of the uppermost portion of the replenishing roller 11, whereas the height of this copying machine is high. The height h is set higher than the center of rotation of the supply roller 11 and lower than the uppermost point of the roller. In this copying machine in which the agitators 12 and 13 are continuously rotated, even at this height, the amount of toner accumulated in the area 17 is sufficient to cause the toner to follow the photosensitive drum 1, and the height h This is because it is desirable to reduce the amount of toner remaining in the region 17 as low as possible to prevent the toner aggregation degree from increasing in the region.

Further, in the copying machine according to the first embodiment, the mini agitator 20 is used to loosen the toner in the area 17 and reduce its cohesion. On the other hand, in this copying machine, the toner is not loosened and the area 1
It also serves to return the toner excessively supplied to the area 7 to the area 18. As a result, even if the toner is once excessively supplied to the area 17, the toner is returned from the area 17 to the area 18.

Further, the smaller the volume of the area 17, the faster the toner is used for development, and the deterioration of the image quality due to the load applied to the developer is less likely to occur.
However, if the volume of the region 17 is too small, when a large amount of toner is required for development, there is a risk that the toner will be insufficient and the image quality will be degraded. Therefore, in this copying machine, the area 1
The volume of 7 is made larger than the volume of the maximum amount of toner used in one developing operation to avoid such danger.

In the copying machine described above, the area 1
Sensor and agitator 1 to detect the amount of toner inside 7.
Since the amount of toner supplied to the region 17 can be adjusted without providing a clutch or the like for disconnecting the drive transmission to 2 and 13, the manufacturing cost of the copying machine can be kept low. However, in a high-speed copying machine or the like that consumes a large amount of toner, it may be difficult to cope with this configuration. Therefore, the area 1 that is also effective in the following cases
A modification of a copying machine having a configuration for adjusting the amount of toner replenished to No. 7 will be shown.

FIG. 4 is a block diagram showing a circuit for controlling the copying machine according to this modification, and FIG. 5 is a flow chart showing the control. In the copying machine according to this modification, the writing amount of the electrostatic latent image formed on the photosensitive drum 1 is integrated and measured by the circuit shown in FIG. 4 as the latent image forming amount integrating means. Then, this measured value is compared with a value determined in advance by an experiment, and when the measured value is larger, the toner is replenished to the developer reservoir 17 (hereinafter referred to as the area 17). Here, in order to replenish the area 17 with toner, for example, an electromagnetic clutch is provided in a drive system for transmitting the rotational driving force to the agitators 12 and 13, and the drive is transmitted to the agitators 12 and 13 using the clutch. A configuration can be adopted.

[Third Embodiment] A third embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine) which is an image forming apparatus will be described below. FIG. 6 is a schematic configuration diagram of the copying machine according to the present embodiment. In addition, about the structure similar to 1st Embodiment and 2nd Embodiment, only the same code | symbol as what was shown in FIG. 1 which shows 1st Embodiment in FIG. 6 is attached | subjected, and the description is abbreviate | omitted. . As shown in FIG. 6, this copying machine has an optical sensor 43 as a density detection sensor for detecting the density of a toner image as a visible image formed on the photosensitive drum 1. As shown in FIG. 7, which is an explanatory view showing the optical sensor 43 in an enlarged manner, the light receiving section 43b receives the light emitted from the light emitting section 43a to the photosensitive drum, and the intensity of the received light is increased. Thus, the density of the toner image on the surface of the photosensitive drum 1 is detected.

The optical sensor 43 described above is used to detect the density of the pattern image 40 formed of the toner image formed on the surface of the photosensitive drum 1 as shown in FIG.
The pattern image 40 does not appear on the image to be formed because it is several centimeters later on the surface of the photosensitive drum 1 than the toner image corresponding to the image to be formed. Then, as shown in FIG. 9, the integrated value of the density of the pattern image detected and measured by the optical sensor 40 is compared with a predetermined value, and when the integrated value is larger, the developer reservoir 17 Toner is supplied to (hereinafter referred to as area 17). Here, in order to replenish the area 17 with toner, for example, an electromagnetic clutch is provided in the drive system for transmitting the rotational driving force to the agitators 12 and 13 as in the copying machine of the second embodiment, and the clutch is used. A configuration in which the drive is transmitted to the agitators 12 and 13 can be adopted.

[0036]

According to the first aspect of the present invention, the developer is transferred to the developer pool portion only when the developer amount sensor detects that the amount of the developer in the developer pool portion is equal to or less than a predetermined amount. Since the developer is transported, deterioration of the developer is less likely to occur in other cases than in the case where the developer is transported. Therefore, the deterioration of the image quality due to the use of the developer, which has deteriorated with time due to the conveyance or the like, in the image formation does not occur, and the image formation of good quality can be performed.

According to the second aspect of the present invention, the developer in the solidified state is not used for image formation because the developer is agitated by the stirring means. The deterioration of the image quality due to being used for the formation is prevented, and the image formation of a better quality is performed.

According to the third aspect of the invention, since the change in the cohesion degree of the toner used for image formation is 10% or less, the deterioration of the image quality due to the drastic change in the cohesion degree does not occur. Thus, good quality image formation can be performed.

According to the invention of claim 4, the developer is accumulated in the developer only when the amount of the latent image formed by the latent image accumulating means and formed on the latent image carrier exceeds a predetermined amount. Since the developer is conveyed and supplied to the section, deterioration of the developer is less likely to occur in other cases than in the case where the developer is conveyed. Therefore, the deterioration of the image quality due to the use of the developer, which has deteriorated with time due to the conveyance or the like, in the image formation does not occur, and the image formation of good quality can be performed.

According to the fifth aspect of the present invention, the developer is added only when the integrated value of the densities of the visible images formed on the latent image other carrier detected by the density detection sensor is equal to or higher than a predetermined density. Since the developer is supplied to the developer pool, deterioration of the developer is less likely to occur in other cases than in the case where the developer is conveyed and supplied. Therefore, the deterioration of the image quality due to the use of the developer, which has deteriorated with time due to the conveyance or the like, in the image formation does not occur, and the image formation of good quality can be performed.

According to the invention of claim 6, even when an image is formed using a large amount of developer such as an image containing a lot of solid portions, the developer is insufficient in forming the image. As a result, the image density is prevented from lowering due to the insufficient supply amount of the developer, and the image formation with better quality is realized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a copying machine according to a first embodiment.

FIG. 2 is an explanatory view showing an enlarged part of the copying machine.

FIG. 3 is a schematic configuration diagram of a copying machine according to a second embodiment.

FIG. 4 is a block diagram showing a control circuit of a copying machine according to a modification of the copying machine.

FIG. 5 is a flowchart showing control of the copying machine.

FIG. 6 is a schematic configuration diagram of a copying machine according to a third embodiment.

FIG. 7 is an explanatory view showing a part of the copying machine in an enlarged manner.

FIG. 8 is an explanatory view showing a pattern image formed on a photosensitive drum provided in the copying machine.

FIG. 9 is a flowchart showing control of the copying machine.

FIG. 10 is a graph showing a problem of a conventional copying machine.

[Explanation of symbols]

 1 Photoreceptor Drum 10 Developing Roller 11 Supply Roller 12 Agitator 13 Agitator 14 Blade 15 Casing 16 Tailoring Member 17 Developer Reservoir 19 Sensor 20 Mini Agitator 40 Pattern Image 42 Optical Sensor

Front page continuation (72) Inventor Nobuyuki Koinuma 1-3-6 Nakamagome, Ota-ku, Tokyo In Ricoh Co., Ltd. (72) Inventor Akira Sawada 1-3-6 Nakamagome, Ota-ku, Tokyo In Ricoh

Claims (6)

[Claims] 1. An image forming apparatus for forming an image by developing a latent image formed on a latent image carrier by a developing device, wherein the developing device includes a casing part in which a developer is held. A developer carrier for supplying the developer carried on the surface to the latent image carrier to develop the latent image, and a developer provided inside the casing part and provided with the developer carrier inside thereof. A developer reservoir, a developer supply unit that conveys the developer in the casing and supplies the developer to the developer reservoir, and a developer amount detection sensor that detects the amount of the developer in the developer reservoir. When the developer amount sensor detects that the amount of the developer in the developer reservoir is equal to or less than a predetermined amount, the developer supply unit is driven to supply the developer to the developer reservoir. And a developer supply control means An image forming apparatus characterized by being a component type developing apparatus. 2. The image forming apparatus according to claim 1, further comprising a developer agitating means for agitating the developer in the developer reservoir. 3. An image forming apparatus for forming an image by developing a latent image formed on a latent image bearing member by a developing device, wherein the developing device includes a casing part in which a developer is held. A developer carrier for supplying the developer carried on the surface to the latent image carrier to develop the latent image, and a developer provided inside the casing part and provided with the developer carrier inside thereof. And a developer supplying unit that conveys the developer in the casing unit and supplies the developer to the developer reservoir unit. After the developer is supplied into the casing, the developer is supplied next. The change in the degree of cohesion of the developer before the supply of
An image forming apparatus, which is a one-component system image forming apparatus in which the developer supplying capability of the developer supplying unit is set to be less than or equal to a percentage. 4. An image forming apparatus for forming an image by developing a latent image formed on a latent image carrier by a developing device, wherein the developing device includes a casing part in which a developer is held. A developer carrier for supplying the developer carried on the surface to the latent image carrier to develop the latent image, and a developer provided inside the casing part and provided with the developer carrier inside thereof. A developer reservoir, a developer supply unit that conveys the developer in the casing and supplies the developer to the developer reservoir, and a latent image that integrates the amount of the latent image formed on the latent image carrier. Amount supply means and a developer supply means for driving the developer supply means to supply the developer to the developer reservoir when the amount of the latent image integrated by the latent image integration means exceeds a predetermined amount. It is a one-component developing device equipped with control means. An image forming apparatus. 5. An image forming apparatus, which develops a latent image formed on a latent image carrier by a developing device to form a visible image to form an image, the visible image formed on the latent image carrier. The developing device is provided with a density detecting sensor for detecting the density of the latent image, and the developing device supplies the latent image bearing member with the casing part in which the developer is held and the developer carried on the surface to form the latent image. A developer carrying member for developing, a developer reservoir portion provided inside the casing portion, the developer reservoir portion having the developer bearing member therein, and a developer carrying member in the casing portion to develop the developer in the developer reservoir portion. When the integrated value of the density detected by the density detection sensor and the developer supply means for supplying the developer becomes a predetermined value or more, the developer supply means is driven to supply the developer to the developer reservoir. And the developer supply control means Image forming apparatus which is a one-component developing device was e. 6. The image forming apparatus according to claim 1, wherein a volume of the developer reservoir is larger than a maximum volume of the developer used in one image forming operation. An image forming apparatus characterized by.