JPH096116A - Developing device - Google Patents

Abstract

PURPOSE: To provide a developing device constituted so that developer or a developing unit need not be exchanged and the developer can be continuously used by prolonging the life of the developer by preventing the developer from being deteriorated caused by a long-time use and replenishment with new toner when the toner is detected to be exhausted. CONSTITUTION: A magnetic pole is arranged inside a developing sleeve 4 facing a prescribed-capacity developer retention part A where the developer obstructed by a doctor 6 is retained. A predoctor hood 7 guiding the developer while regulating the movement thereof in a direction orthogonally crossing a developing carrying direction is provided inside a supporting case and in an area whose magnetic flux density of a magnetic field in the normal line direction on the surface of the sleeve 4 generated by a magnet roller 5 housing the magnetic pole is equal to or under a prescribed value. Besides, a toner residual quantity sensor 10 is provided at a position where the residual quantity of toner can be detected in a state where the toner exists at the uppermost part of a boundary surface where the toner in a toner hopper 8 is brought into contact with the developer.

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 or a printer, and more specifically, a developer carrier for carrying a developer composed of toner and magnetic particles, and the developer. A magnetic field generating means disposed inside the carrier, a developer restricting member for restricting the amount of the developer carried on the developer carrier, and a predetermined volume for retaining the developer blocked by the developer restricting member. The developer accumulating portion is adjacent to the developer accumulating portion from upstream in the developer conveying direction on the developer carrying member, and the stored toner is the developer carried on the developer carrying member or the staying toner. And a toner accommodating portion having a toner replenishment opening that comes into contact with the developer, and the toner in the toner accommodating portion is taken into the developer carried by the developer carrier.

[0002]

2. Description of the Related Art Conventionally, as a developing device of this type, a magnetic particle layer is formed on a developer carrying member in a container,
The toner is accommodated in the toner supply unit in the container so as to come into contact with the magnetic particle layer, and the magnetic particles in the magnetic particle layer move with the rotation of the developer carrier having a magnet fixedly arranged inside the toner. The toner is taken into the magnetic particle layer at the supply unit, and the developer in which the toner and the magnetic particles are mixed,
In a developing device in which a developer regulating member regulates a layer thickness and conveys the toner to a developing region, the magnet does not have a magnetic pole facing the toner replenishing portion, and a downstream side of the toner supplying portion with respect to a rotation direction of a developer carrying member. And has a magnetic pole on the upstream side of the regulating member, and is provided on the downstream side of the toner supply section and on the upstream side of the regulating member at a position within the range of the magnetic field of the magnetic pole so as to face the developer carrying member. There is known a developing device having a shielding member that forms a region filled with the magnetic particle layer between the developer carrying member and the developer carrying member (see, for example, JP-B-5-67233).

[0003]

By the way, in the developing device proposed in Japanese Patent Publication No. 5-67233, when the amount of the developer present in the region filled with the magnetic particle layer becomes a little too large, the developer regulation is restricted. Except for those that pass through the gap between the member and the developer carrying member, the developer hardly moves, so when image formation is performed with a slightly higher toner consumption amount, new toner is supplied to the developer that contributes to development. Will be difficult. Therefore, in order to activate the movement of the developer existing in the developer circulation region, it is preferable to set a small amount of developer in the case of this developing device.

On the contrary, when the amount of the developer is too small, the toner density becomes too high and the toner is insufficiently charged, so that problems such as background stains and in-machine contamination due to toner scattering are likely to occur. Further, the developer layer formed near the surface of the developer carrying member is a moving layer that moves with the rotation of the developer carrying member in the vicinity of the developer carrying member, and above the moving layer. At first glance, it separates into a stationary layer, and the developer in the moving layer frequently contributes to toner transport, which causes severe deterioration of the developer such as toner spent and magnetic particle film abrasion. The life will be shortened. Furthermore, since this developing device cannot set a large amount of developer, it is limited to use in an image forming device (for example, an image forming device capable of forming an image of about several thousand sheets) which may have a very short developer life. It is necessary to frequently change the developer in such a form that the developer replacement time is grasped by using a sheet number detecting means and the entire developing unit is replaced.

Further, if the toner is consumed even before the life of the developer, a sufficient amount of toner is not taken into the developer and the toner density becomes insufficient, especially in a developing device with a small amount of developer. However, this effect immediately appears in the developed image. For example, if the toner end time is unknown and the toner concentration falls below a predetermined concentration, the frequency of contact between carriers increases and the film coating the magnetic powder is scraped off too much, resulting in a marked decrease in toner charging ability. Will end up. Then, the toner is not charged to the desired charge amount,
Stains on the latent image carrier of the image forming apparatus and toner scattering easily occur. Further, since the magnetic powder core material has a lower resistance than the coating film, the thinner the magnetic powder coating film is, the lower the magnetic powder resistance is, and the magnetic powder adheres to the latent image carrier. Will end up. Furthermore, when this magnetic powder adheres, the magnetic powder in the developing unit decreases and the amount of developer becomes insufficient. Also, transfer dropout, cleaning blade chipping, latent image carrier and fixing roller damage, etc. There is a problem that the powder causes various problems in other parts.

The present invention has been made in view of the above problems, and an object of the present invention is to set the toner density to such an extent that the developer does not adhere to the image carrier and the image density does not decrease. The remaining toner amount is detected so as to determine the toner end while keeping the toner remaining amount, and only the toner is replenished based on the result of the remaining toner amount detection, thereby reducing the unevenness of the toner density and the toner charge amount, and the uneven image density. ,
It is an object of the present invention to provide a developing device capable of preventing background stains, toner scattering, etc., and extending the life of the developer as much as possible.

[0007]

In order to achieve the above-mentioned object, a developing device according to a first aspect of the invention is a developer carrier for carrying a developer comprising toner and magnetic particles, and the developer carrier. A magnetic field generating means disposed inside, a developer regulating member for regulating the amount of the developer carried on the developer carrying member, and a predetermined amount of developer retention for retaining the developer blocked by the developer regulating member. Section adjacent to the developer holding portion from the upstream side in the developer conveying direction on the developer carrying member, and the toner stored in the developer carrying member is developed on the developer carrying portion or the developing portion. And a toner accommodating portion having a toner replenishing opening that comes into contact with the developer, and the toner in the toner accommodating portion is taken into the developer carried on the developer carrier. Located on the wall surface of the upper toner container, In which it characterized in that a remaining toner amount detecting means for detecting the toner remaining amount.

According to a second aspect of the present invention, there is provided the developing device according to the first aspect, wherein a toner container for replenishing the toner in the toner containing section is provided above the toner containing section. .

A developing device according to a third aspect is the developing device according to the first aspect, wherein the toner accommodated in the toner accommodating portion is conveyed to the toner replenishing opening side around the fixed shaft in the toner accommodating portion. The toner transporting means for rotating the toner transporting means is provided so that the lowermost end of the outermost rotation trajectory of the toner transporting means is located at the uppermost part of the boundary surface where the stored toner and the developer in the toner accommodating portion come into contact with each other. It is characterized in that a detection level for level detection is set.

According to a fourth aspect of the present invention, in the developing apparatus according to the first, second or third aspect, the toner remaining amount detecting means is configured by using a sensor that directly detects the toner in the toner containing portion. It is characterized by.

According to a fifth aspect of the present invention, in the developing apparatus according to the first, second or third aspect, a part of the toner containing portion is formed of a transparent member, and the toner remaining amount detecting means is provided outside the toner containing portion. It is characterized by using a sensor for detecting the remaining amount of toner in a non-contact manner via the transparent member.

[0012]

In the developing device according to any one of claims 1 to 5, the developer in the developer retaining portion carried on the developer carrying member by the magnetic field generated by the magnetic field generating means is conveyed as the developer carrying member moves. It Then, the transported developer is regulated by the developer regulating member and then supplied to the developing area facing the image carrier. The developer not used for development in the development area is
The developer is further transported as the surface of the developer carrier moves, takes in toner from the toner replenishing opening, and then returns to the developer retaining portion. On the other hand, the developer regulated by the developer regulating member and not supplied to the developing area moves above the developer retaining portion, and seems to stay in the developer retaining portion without contributing to the toner conveyance. To form a developer retention layer that looks visible. Then, the developer in the staying layer is regulated by the developer regulating member, and is forcibly moved in a direction opposite to the conveying direction on the surface of the developer carrying member by the developer moving upward one after another. To be made. When it reaches a position where it is less likely to be affected by the magnetic field from the developer carrying member, it moves toward the toner replenishing opening of the toner containing section due to the internal pressure and gravity of the developer itself in the developer retaining section. And
The developer retention layer that has moved to the vicinity of the toner replenishing opening is again transferred to the developer regulating member side while taking in toner from the opening along with the movement of the developer moving layer that is being conveyed on the surface of the developer carrier. The developer is conveyed and rotates so as to circulate in the developer accumulating portion.

Here, when the amount of the toner taken in the developer increases and the toner concentration increases, the volume of the developer in the developer moving layer also increases, and the developer flows through the toner replenishing opening. It will move to the closing position. By thus closing the toner supply opening with the circulating developer, the amount of toner taken into the developer on the developer carrier is reduced. Due to this decrease in the toner intake amount, the toner concentration of the developer is always kept below a certain concentration.

Particularly, in the developing device according to the first aspect, the toner in the toner containing portion is consumed by the use,
When the upper surface of the toner reaches the detection position of the toner remaining amount detecting means installed in the toner containing portion, it is determined by the toner remaining amount detecting means that the toner is insufficient. Here, the toner remaining amount detection means detects the toner remaining amount shortage in a state where the toner exists in the uppermost part of the boundary surface where the toner in the toner storage portion contacts the developer. As a result, even when the remaining amount of toner in the toner storage unit reaches the detection level, the remaining amount is detected in a state where the toner can be reliably taken into the developer. When the toner remaining amount detecting means determines that the toner remaining amount is insufficient, the operator is urged to replenish the toner accommodating portion with new toner through, for example, the display means. Therefore, by replenishing the toner in the toner containing portion based on such a display to the operator, the developer can be continuously used without being frequently replaced, and the image density of There is no significant decrease or the adhesion of the developer on the image carrier.

Particularly, in the developing device according to the second aspect, the toner is replenished into the toner containing portion through the toner discharge port of the toner container based on the detection result of the insufficient toner amount by the toner remaining amount detecting means. .

Particularly, in the developing device according to the third aspect, the lowermost end of the outermost peripheral rotation locus of the toner conveying means is located at the uppermost part of the boundary surface where the stored toner in the toner accommodating portion and the developer come into contact with each other. Since the detection level for toner level detection is set so that it is positioned, even if the remaining toner amount decreases due to use, it is possible to ensure that the toner remains in the developer on the surface of the developer carrier until the detection level is reached. And it conveys toner smoothly.

Particularly, in the developing device according to the fourth aspect, the sensor as the toner remaining amount detecting means detects the toner remaining amount in the toner containing portion by directly contacting the toner.

Particularly, in the developing device of the fifth aspect, the sensor as the toner remaining amount detecting means detects the toner remaining amount in the toner containing portion from outside the toner containing portion through the transparent member in a non-contact manner. (Hereinafter, margin)

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a developing device used in an electrophotographic copying machine (hereinafter referred to as "copying machine") which is an image forming apparatus will be described below. FIG. 1 is a partial cross-sectional view showing a schematic configuration of the developing device according to this embodiment.
This developing device is a cylindrical photosensitive drum 1 which is an image carrier.
A support case 2 which is disposed laterally of the photosensitive drum 1 and has an opening formed toward the photosensitive drum 1, a part of which is exposed from the opening.
From a developing sleeve 4 as a developer carrying member carrying a developer 3 composed of toner and magnetic particles (hereinafter referred to as “carrier”) on its surface, and a fixed magnet group as a magnetic field generating means fixedly arranged inside the developing sleeve 4. A magnet roller 5, a doctor 6 as a developer regulating member that regulates the amount of the developer carried on the developing sleeve 4 and conveyed,
The doctor sleeve 7 is formed above the developing sleeve 4 so as to form a retaining portion of the developer, and the toner hopper 8 as a toner accommodating portion is provided. The polarity of the magnetic pole on the surface of the magnet roller 5 is shown inside the developing sleeve 4 in FIG.

The doctor's front hood 7 is the developing sleeve 4
And a developer accumulating portion A in which the developer, which is not supplied to the developing position of the portion facing the photosensitive drum 1 and whose movement is blocked by the doctor 6, is accumulated. A magnet roller 5 is provided inside the developing sleeve 4 facing the developer accumulating portion A.
The magnetic pole 5a is arranged. Further, the toner hopper 8 is
A toner replenishing port 8a is provided adjacent to the upstream side of the developer retaining portion A in the developer conveying direction and facing the surface of the developing sleeve 4, and the toner in the hopper 8 is provided in a space adjacent to the toner replenishing port 8a. A toner agitator 9 is provided as a toner conveying member for feeding 3a toward the toner supply port 8a while stirring.

The pole important in the magnetic pole construction of the magnet roller 5 is the P ₄ pole indicated by the symbol D in FIG. 2A, which is arranged opposite to the developer retaining portion A and has the developer retaining portion A. Gravity can sufficiently contribute to the movement of the developer in the inside, that is, the front end portion 7a of the doctor's front knee on the toner supply port 8a side.
The magnetic force distribution is such that the magnetic force of P ₄ does not reach so much. In order to obtain the magnetic force distribution in the apparatus of the present embodiment, the polar angle of the P ₄ pole is ± 10 with the rotation shaft of the developing sleeve 4 as the center, with the position facing the point D as a reference.
The magnetic flux density on the developing sleeve 4 in the range of 50 °
The magnetic flux density is set to 80 mT and the half width of the magnetic flux density is set to 20 ° to 60 °. As other setting conditions, the saturation magnetic flux density of the carrier is 50 to 90 emu / g,
The distance L between the developing sleeve 4 and the front of the doctor 7 is 10
mm or more. Of course, with respect to the carrier itself in the developer, conventional techniques for minimizing changes in physical properties due to use over time, for example, techniques for preventing carrier spent, carrier surface abrasion, carrier chargeability change, etc. It is desirable to actively adopt it.

Further, in FIG. 1, an auxiliary line Q drawn from the rotation center P of the developing sleeve 4 toward the front end portion 7a of the doctor's front desk 7 and the doctor 6 from the rotation center P of the developing sleeve 4 are shown.
Auxiliary line R drawn along the surface in the vertical direction, and an auxiliary line S drawn so that the angle formed by the auxiliary line Q and the auxiliary line R becomes 1/2.
Of these, in the developer retaining portion A, the auxiliary line S and the auxiliary line Q are surfaces extending in the axial direction of the developing sleeve 4, respectively.
Let V be the volume of the area surrounded by the surface of the developing sleeve 4 and the surface of the doctor's front histories 7 facing the developing sleeve 4.
The amount of developer actually present in the region (volume V) is W, and the apparent density of the developer 3 is ρ _D (usually 1.4 to 2.2 g / cm ³
Range), the developer amount W is the volume V and the density ρ.
The shape of the front doctor's pad 7 and the amount W of the developer to be stored in the developer accumulating portion A are set so that a relationship smaller than the product with _D is established.

In the developing device having the above-described structure, the developer 3 on the developing sleeve 4 is conveyed as the sleeve 4 rotates in the direction of the arrow, and is regulated by the doctor 6 to form a thin layer. The thinned developer 3 is conveyed to a developing area facing the photoconductor drum 1 rotating in the arrow direction. Then, in the developing area, toner is supplied to the electrostatic latent image formed on the photosensitive drum 1, and the electrostatic latent image is visualized. Developer 3 not used for this visualization
Is conveyed with the rotation of the developing sleeve 4, takes in the new toner 3a sent from the agitator 9 and supplied from the toner supply port 8a, and then returns to the developer accumulating portion A. Then, the internal pressure of the developer 3 containing the new toner 3a increases due to the restriction by the doctor 6, so that the developer 3
The toner is charged. In this way, the toner in the developer 3 on the developing sleeve 4 can be charged by the internal pressure of the developer in the developer accumulating portion A, so that it is complicated to charge or agitate the developer 3 such as a paddle or a screw. No special stirring mechanism is required.

On the other hand, a part of the developer 3 which is not supplied to the developing area and whose progress is blocked by the doctor 6 is replenished with toner in the toner hopper 8 by the internal pressure and gravity of the developer 3 itself in the developer accumulating portion A. Move toward mouth 8a. The developer 3 in the developer retention layer that has moved to the vicinity of the toner supply port 8a
Rotates with the movement of the developer moving layer accompanying the rotation of the developing sleeve 4 so that the developer moving layer is conveyed to the doctor 6 side and circulates.

2 (a) to 2 (c) show a developer retention portion A.
The rotational movement of the developer 3 in Example 1 was observed by magnifying the side surface using a high-speed video, and capturing the different color toner in the developer by photographing at 200 frames / sec and 10 × speed. A part of the developer in the developer retention layer, which is conveyed to the downstream side in the rotation direction of the developing sleeve 4 so as to hit the doctor 6, partially moves above the developing sleeve 4 due to the magnetic force lines formed by the magnet roller 5 and gravity. And flows in the developer accumulating portion A to make a rotational movement.

The toner in the toner hopper 8 is as shown in FIG.
Confluence point c between the flow indicated by symbol a and the flow indicated by symbol b
It is taken into the developer from the vicinity. At this time, the developer moving layer is about 100 mm / sec near the surface of the developing sleeve 4.
Since there is still a sufficient gap in the developer retention portion A, the rotation speed of the developer retention layer is about 10 mm / sec.

Next, as shown in FIG. 2B, when the toner concentration gradually increases and the developer moving layer expands, the confluence point c
Is gradually separated from the vicinity of the surface of the developing sleeve 4, the flow velocity a of the developer near the surface of the developing sleeve 4 is decreased, and the developer 3 is moving near the surface at a speed of about 65 mm / sec. The rotation speed of the agent retention layer is about 5 mm / se
c.

Next, as shown in FIG. 2C, when the amount of toner replenished to the developer 3 increases and the toner concentration increases,
Along with that, the bulk of the developer 3 increases, and voids disappear in the developer retaining portion A, so that the fluidity of the developer 3 gradually deteriorates. Therefore, as the developer moving layer expands, the confluence point c approaches the front end portion 7a of the knee. As a result, the toner is no longer taken into the developer. At this time, the rotation speed of the developer retention layer is about 1 mm.
/ Sec. However, in the developer retention layer, there is a portion where the developer is still retained in a loosely packed state, the developer 3 in this portion has a relatively high toner content as compared with the other portions, and the flow velocity is very slow. However, the rotational movement continues, in which the dispersion of toner in the developer and the start-up of charging are in progress.

When the toner is consumed by the development and the toner concentration in the developer retaining portion A decreases, and the bulk of the developer 3 decreases, the state of FIG. The toner starts to be taken into the agent.

As described above, the toner concentration is self-controlled by changing the developer volume in the developer retaining portion A according to the toner intake state, so that the toner concentration of the developer 3 is always substantially constant. Keeped in range.
For this reason, a complicated toner concentration control mechanism such as a toner concentration sensor and a toner replenishing member becomes unnecessary.

Further, at this time, not only the toner newly taken into the developer but also the toner dispersed in the developer while rotating in the developer retention layer as described above, and the charged electric charge rises Of course is also transported to the development area,
Even when a large amount of charged toner is used for development and a large amount of toner is taken into the developer from the hopper 8, as in the apparatus described in Japanese Patent Publication No. 5-67233, the amount of toner Problems such as background stains and toner scattering due to insufficient charging are less likely to occur.

A toner remaining amount sensor 10 as a toner remaining amount detecting means shown in FIG. 1 detects the amount of toner in the toner hopper 8 by contacting with the toner. A piezoelectric vibrator that can be obtained at a relatively low cost can be used. In the illustrated example, this sensor 1
0 is fixed to the side wall of the toner hopper 8, and its position is such that the carrier and the toner are in contact with each other so that the toner remaining amount can be detected while the developer 3 still has enough toner to be taken in. It's set to a slightly higher level than the top that you get.

Here, the developer 3 in the developer retaining portion A is
Since the developer 3 is circulated in the retaining portion A as described above, deterioration of the developer 3 is less likely to occur than in a device that does not circulate, and the toner in the toner hopper 8 is consumed and disappears due to use. However, the developer 3 still has a sufficiently long life that it can be used as compared with the case where it is used in the conventional apparatus.

Then, the toner in the toner hopper 8 is consumed by the use, and the upper surface of the toner is at the toner remaining amount sensor 10.
When the toner remaining amount sensor 10 fixed to the toner hopper 8 has decreased to the detection position, it is determined that the toner remaining amount is insufficient. Here, the toner remaining amount sensor 10
Detects the toner remaining amount level in a state where the toner in the toner hopper 8 is present at the uppermost part of the boundary surface in contact with the developer 3. As a result, even if the toner remaining amount in the toner hopper 8 reaches the detection level, the toner remaining amount is detected in a state where the toner can be reliably taken into the developer 3. When the toner remaining amount sensor 10 determines that the toner remaining amount is insufficient, the operator is urged to replenish the toner in the toner hopper 8 through a display unit (not shown). Therefore, the image density is not remarkably reduced and the carrier is not attached to the photosensitive drum 1 before the toner remaining amount is detected. Then, based on this display, the toner is replenished in the toner hopper 8. As a result, it is possible to continuously and effectively use the developer without exchanging the developer which still has the characteristics that can be sufficiently used.

According to the above-described embodiment, even when the toner hopper 8 is consumed from the full state to the toner remaining amount insufficient level, the developer 3 used for the development still maintains the characteristic that it can be used sufficiently. . As a result, the toner is surely replenished in the hopper 8 at a level at which the shortage of the remaining amount of toner can be detected, so that the developer 3 can be continuously used, the image density is lowered, and the carrier to the photosensitive drum 1 is reduced. It is possible to prevent the occurrence of adhesion.

In the above embodiment, the toner remaining amount sensor 10 is fixed to the side wall of the toner hopper 8.
Instead, as shown in FIG. 3, a part of the toner hopper 8 corresponding to the position set as the remaining toner level is made of a transparent member, and the remaining toner amount can be detected outside the toner hopper 8 in a non-contact state with the toner. As described above, for example, an optical detection type sensor 11 may be used to detect insufficient toner remaining amount. According to this, since the toner remaining amount shortage is detected in a non-contact manner through the transparent member, the existing inexpensive sensor can be attached to the apparatus main body side without being attached to the toner hopper 8, and the sensor is separated from the toner hopper 8. Since it can be attached by the body, the wiring of connectors is unnecessary,
There is an advantage that it is inexpensive and effective in simplifying the device configuration and reducing the cost. As such an optical detection type detection sensor 11, several detection methods as shown in FIGS. 6 (a) to 6 (c) are known. FIG. 6 (a)
Is a transmission type detection method in which a projector and a light receiver are opposed to each other, and light from the projector is shielded by an object to be detected to obtain a control output. FIG. 6 (b)
It is a detection method called retroreflective type, in which light is reciprocated through a retroreflective plate, and the light is intercepted by the object to be detected in the middle to obtain a control output. Similarly, it is intended to detect interruption of optical coupling. FIG. 6C shows a detection method called a diffuse reflection type, which operates by the surface reflection of the detected object itself.

Further, in FIG. 4, even when the agitator 9 is arranged at a position higher than the position shown in FIG. 1, the toner remaining amount sensor is arranged so that at least the lowermost part of the rotation locus of the agitator 9 is located in the toner reservoir. 10 is provided. According to this, in addition to obtaining the same effect as described above, the amount of toner remaining in the hopper 8 decreases, and the toner is moved to the developing sleeve 4 side by the rotation of the agitator 9 immediately before the insufficient toner amount is detected. It can be sent reliably.

Further, the present invention can be applied to a developing device equipped with the toner bottle 12 as shown in FIG. In this case, the installation position of the toner remaining amount sensor 10 needs to be set to a level lower than the toner outlet 12a of the toner bottle 12 and slightly higher than the uppermost portion where the carrier and the toner can come into contact with each other. According to this, even if the toner remaining amount sensor 10 detects the toner remaining amount shortage, the toner can be automatically replenished into the hopper 8 via the toner discharge port 12a of the toner bottle 12, so that the operator can It is possible to eliminate the trouble of frequently replenishing the deficient toner. Further, since the toner bottle 12 itself can be attached to and detached from the main body of the developing device, the toner bottle 12 can be easily replaced.

[0039]

According to the developing device of the first to fifth aspects, the toner remaining amount detecting means does not cause the magnetic powder to adhere to the image carrier of the image forming apparatus and does not reduce the image density. Since the shortage of the remaining amount of toner is detected at the toner concentration level, the toner is surely replenished in the developer even when the remaining amount of toner in the toner storage portion reaches the remaining amount detection level of toner. Therefore, for example, when the operator replenishes the toner based on the result of such detection, the toner can be surely supplied into the developer before the toner concentration in the developer is remarkably reduced. There is an excellent effect that it is possible to prevent the image density from decreasing before the remaining amount is detected and to prevent the magnetic powder from adhering to the image carrier. Further, since the toner concentration does not decrease remarkably, it is possible to prevent deterioration caused by rubbing between magnetic particles and the like, and the service life due to use over time is short as in the case where a small amount of magnetic particles are used. Even if it is a thing, the life can be extended as much as possible. Furthermore,
When the remaining amount of the toner is insufficient, it is not necessary to replace the magnetic particles or the developing unit containing the magnetic particles only by replenishing the toner.

Particularly, according to the developing device of the second aspect, the toner is automatically stored in the toner containing portion via the toner discharge port of the toner container based on the detection result of the toner remaining amount shortage by the toner remaining amount detecting means. Since it is possible to replenish the toner, it is possible to eliminate the troublesomeness of the operator to frequently replenish the shortage of toner, and it is possible to easily replace the toner container itself.

Particularly, according to the developing device of the third aspect, the toner can be reliably and smoothly conveyed into the developer on the developer carrying member.

Particularly, according to the developing device of the fourth aspect, the existing inexpensive sensor can be used as the toner remaining amount detecting means by directly contacting with the toner.
The remaining toner amount can be detected by an easy means, and the cost can be reduced.

Particularly, according to the developing device of the fifth aspect, an existing inexpensive sensor can be used as a sensor for detecting the shortage of the toner remaining amount, and the sensor can be attached separately from the toner accommodating portion. Therefore, since wiring of connectors is not necessary, it is inexpensive and effective in simplifying the device configuration and reducing costs.

[Brief description of drawings]

FIG. 1 is a front view showing a schematic configuration of a developing device of an electrophotographic copying machine according to an embodiment.

FIG. 2A is an explanatory diagram showing a state before starting to take in toner into a carrier. FIG. 6B is an explanatory diagram showing a process of taking toner into a carrier. FIG. 7C is an explanatory diagram showing a state in which the toner has been taken into the carrier.

FIG. 3 is a front view showing a schematic configuration of a developing device of an electrophotographic copying machine according to a modified example of the same embodiment.

FIG. 4 is a front view showing a schematic configuration of a developing device of an electrophotographic copying machine according to another embodiment.

FIG. 5 is a front view showing a schematic configuration of a developing device of an electrophotographic copying machine according to another embodiment.

6A to 6C are explanatory views showing a detection method of an optical detection type detection sensor.

[Explanation of symbols]

1 Photoconductor drum 2 Developer casing 3 Developer 3a Toner 4 Development sleeve 5 Magnet roller 5a Magnetic pole (P ₄ pole) 6 Doctor 7 Doctor front edge 7a Tip part 8 Toner hopper 8a Toner supply port 9 Toner agitator 10 Piezoelectric residual toner amount Sensor 11 Optical detection type toner remaining amount sensor 12 Toner bottle 12a Toner discharge port

Claims (5)

[Claims] 1. A developer carrying member for carrying a developer comprising toner and magnetic particles, a magnetic field generating means arranged inside the developer carrying member, and a developer carried on the developer carrying member. A developer regulating member for regulating the amount, a developer accumulating portion of a predetermined volume in which the developer blocked by the developer regulating member accumulates, and a developer conveying direction on the developer carrier to the developer accumulating portion. And a toner accommodating portion having a toner replenishment opening portion in which the accommodated toner comes into contact with the developer carried on the developer carrier and the developer in the staying portion. In a developing device adapted to take in the toner inside the developer into the developer carried on the developer carrying member, the remaining toner amount detection for detecting the remaining toner amount is located on the wall surface of the toner containing portion above the toner supply opening portion. The current feature characterized by the provision of means Image device. 2. The developing device according to claim 1, wherein a toner container for replenishing the toner in the toner container is provided above the toner container. 3. A toner conveying means is provided inside the toner accommodating portion, which rotates about a fixed shaft so as to convey the toner accommodated in the toner accommodating portion to the toner supply opening side. A detection level for toner level detection is set at an uppermost part of a boundary surface where the accumulated toner and the developer in the toner accommodating portion come into contact with each other at a lowermost end part of the outermost rotation trajectory of the conveying means. The developing device according to claim 1. 4. The developing device according to claim 1, 2 or 3, wherein the toner remaining amount detecting means is constituted by using a sensor for directly detecting the toner in the toner containing portion. 5. A part of the toner containing portion is formed of a transparent member, and the toner remaining amount detecting means is a sensor for detecting the remaining amount of toner from outside the toner containing portion through the transparent member in a non-contact manner. The developing device according to claim 1, 2 or 3, wherein the developing device is configured by using the developing device.