JP2002278248A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device which obtains an excellent image having no surface stain, etc., by properly receiving toner by making the toner present nearby a developer circulation part even when the remaining amount of toner is small. SOLUTION: A toner remaining-amount detection sensor 15 is provided on a side wall in a toner storage part 6 and a toner gate member 14 is provided to the bottom part of the toner storage part 6. The toner remaining-amount detection sensor 15 generates an output when the remaining amount of the toner decreases below a previously set value and the toner gate member 14 is turned over only at this time to hold toner with a toner supply path 7; and then toner which is much enough to form a stay part 10 nearby the developer circulation part 11 and part of a developer is prevented from overflowing into the toner storage part 6, so that the toner is properly taken in.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in a developing section of an image forming apparatus such as a copying machine and a laser beam printer, and a process cartridge provided with the developing device.

[0002]

2. Description of the Related Art Conventionally, there has been known a developing apparatus which does not require a toner concentration (percentage by weight of toner contained in the developer) detecting means and controls the toner concentration using a magnetic toner. In these developing devices, the amount of taken-in toner is different between a portion where the developer is active and a portion where the developer is not active, or a portion where the amount of the developer is large and a portion where the amount of the developer is small. Black band-like density unevenness and wavy density unevenness) are likely to occur.

Therefore, attempts have been made to stabilize the toner density by improving the mechanism of the toner take-in section, thereby realizing a more stable and uniform image density. The attempt will be described with reference to a schematic configuration diagram of a conventional developing device shown in FIG. At the lower end of the developer accommodating case 4, a second developer regulating member 9 close to the developer carrier 1 is provided.
Is formed, and when the toner concentration of the developer is within an appropriate range, a stagnant portion 10 of the developer is formed in the toner supply path 7, and the developer and the toner are mixed at the place where the toner is in contact with the developer. No toner is taken in. When the toner is consumed, the bulk of the developer decreases, and the developer stagnation portion 10 decreases, so that the developer circulates below the second developer regulating member 9. When the toner comes into contact with the circulation section 11,
When the toner is taken in by the circulating developer and the bulk increases, the developer stagnant portion 10 is formed again to interrupt the taking of the toner. Further, the developer carrier 1 in the developer accommodating section 3
A rotating developer peeling member 13 is provided in the vicinity, and the developer is intentionally peeled off from the developer carrier 1.
And the developer in the developer accommodating section 3 is replaced. As a result, stress on carriers in the developer is suppressed, and the life of the developer is extended.

In the above-mentioned developing device, the toner replenishment stirring member 8 prevents the toner replenishment path 7 from being supplied to the toner replenishment path 7 by the toner replenishment path 7.
A gentle slope is provided over the bottom. Further, considering the rotation radius and the installation position of the toner supply and stirring member 8 necessary for efficiently stirring the toner in the toner storage section 6, the toner storage section 6 has a shape having a space below the toner supply path 7. I have to be. In such a configuration, when the amount of toner in the toner storage unit 6 is sufficient, the toner is always present very close to the developer circulating unit 11, so that the above-described toner intake system is appropriately repeated. However, in the developing device shown in FIG. 6 in which the toner consumption has advanced, the toner exists only in the space below the toner supply path 7, and sufficient toner to form the above-described stagnant portion 10 near the developer circulating portion 11. Since the developer does not exist, the circulation of the developer does not stop, and a part of the developer is
Overflowing into the interior. Although the toner is slightly supplied by the toner replenishment stirring member 8, the toner is excessively taken in because the amount of the developer sufficient to suppress the taking-in is not held in the circulation portion 11. Due to the mechanism described above, the toner density gradually increases, so that problems such as background contamination near the toner end have occurred. Further, if the toner is exhausted in a state where the remaining amount of toner is large in order to prevent this problem beforehand, a large amount of toner remains without being consumed, which is a problem in cost and is difficult to solve.

[0005]

SUMMARY OF THE INVENTION In view of the above problems, the present invention makes it possible to carry out proper toner taking-in by allowing toner to be present in the vicinity of the developer circulation portion even when the amount of remaining toner is small, thereby making it possible to prevent background contamination. It is an object of the present invention to provide a developing device capable of obtaining a good image free from defects.

[0006]

According to a first aspect of the present invention, there is provided a magnetic recording / reproducing apparatus having a magnetic field generating means therein for carrying a two-component developer containing a toner and a magnetic carrier. A developer carrying member to be conveyed; a first regulating member for regulating an amount of the developer carried and carried by the developer carrying member; and a developer accommodating the developer scraped by the first regulating member. A developer accommodating portion, a second regulating member disposed upstream of the first regulating member in the direction of transport of the developer on the developer carrier, and a developer accommodating portion,
A toner storage section having a toner supply and stirring member member for stirring and supplying the developer to the developer carrying member,
A developer in which the developer blocked by the first regulating member forms a circulation section before the second regulating member (upstream in the developer transport direction), and a sensor provided in the toner storage section. A developing device having a toner blocking member movable by the sensor output signal of the above. According to a second aspect of the present invention, there is provided the developing device according to the first aspect, wherein the number of rotations of the toner supply and stirring member changes according to the sensor output signal. According to a third aspect of the present invention, the developing device according to the first or second aspect is integrally supported together with a photosensitive member and at least one means selected from a charging means and a cleaning means, and is detachably attached to the image forming apparatus main body. The process cartridge is configured as described above.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a developing device according to the present invention. A magnetic field generating means is fixed inside the developer carrier 1, around which the developer carrier 1 is rotatably supported, and a first developer regulating member 2 for regulating the layer thickness of the developer, A developer accommodating case 4 forming a developer accommodating portion 3 for accommodating the developer blocked by the one developer regulating member 2 is provided upstream of the first developer regulating member 2 in the rotation direction of the developer carrier 1. Be placed. A toner storage section 6 for storing the toner 5 is disposed adjacent to the developer storage case 4, and the toner storage section 6 and the developer storage section 3 are connected by a toner supply path 7. A replenishment stirring member 8 for feeding toner toward the replenishment path while agitating the toner is provided in the toner storage unit 6. At the lower end of the developer storage case 4, a developer carrier 1 is provided.
Is formed, and when the toner concentration of the developer is within an appropriate range, a stagnant portion 10 of the developer is formed in the toner supply path 7 so that the toner and the developer come into contact with each other. Where the developer and the toner are not mixed, the toner is not taken in. When the toner is consumed, the bulk of the developer decreases, and the developer stagnation portion 10 decreases, so that the developer circulates below the second developer regulating member 9. When the toner comes into contact with the circulating unit 11, the toner is taken into the circulating developer. Then, when the bulk increases again, the developer stagnation section 10 is formed, and the taking in of the toner is interrupted. Further, the developer carried and transported by the developer carrier 1 is peeled off by a developer peeling member 13 made of a magnetic material provided in the vicinity of the developer carrier 1, and the developer in the developer accommodating section 3 is separated from the developer. Mixing and exchanging efficiently.

An example of conditions for realizing the above operation will be described below. Magnetic poles are alternately arranged inside the developer carrier 1, the magnetic pole facing the image carrier 12 is the P1 pole, and P2 and P3 are arranged in a counterclockwise direction. Arrange P4 pole. When the developer circulating portion 11 takes in the toner and reaches a predetermined concentration, the developer stagnation portion 10 is formed at the contact portion between the toner and the developer. It is necessary to optimize the position of the developer regulating member 9, the shape and position of the space formed in front of the developer regulating member 9 for circulating the developer, and the relative positional relationship of the toner supply path 7. FIG. 2 shows the arrangement diagram obtained based on the experimental results, and the values are shown below. <Mechanical conditions> P3 pole: θ1 = 127 ° Maximum magnetic flux density 61 mT in the direction normal to the developer carrying member P4 pole: θ2 = 36 ° Maximum magnetic flux density 53 mT in the direction normal to the developer carrying member Second developer regulating member angle: θ3 = 14 ° Angle between the vertical surface of the second regulating member facing the developer carrier: θ4 = 24 ° Distance between the second developer regulating member and the surface of the developer carrier: a =
0.9 mm Opening width of toner supply path: b = 5.4 mm Diameter of developer carrier: c = 16 mm <Developer> Carrier: magnetite or iron 40 to 50 μm Toner: Magnetic substance amount 15 to 40 wt% Silica amount 0.5 to The above operation is possible under the condition setting of the coverage of the toner of 1.0 wt% to the carrier 50 to 120% Q / M 10 to 30 μC / g or more, and the toner concentration of the developer can be stabilized. These conditions can be combined to reproduce the above operation under different conditions, and the above-mentioned conditions are examples.

Further, in the developing device of the present invention, as shown in FIG. 1, a toner remaining amount detecting sensor 15 is provided on a side wall inside the toner storing section 6 and a toner blocking member 1 is provided on the bottom of the toner storing section 6.
4 are provided. FIG. 3 is a diagram illustrating the operation of the toner remaining amount detection sensor 15 and the toner blocking member 14. The toner remaining amount detecting sensor 15 outputs when the remaining amount of toner falls below a preset value, and only when the remaining amount of toner falls below the preset value, the toner blocking member 14 inverts to supply toner to the toner supply path 7.
And it can be held between With such a configuration, sufficient toner is formed near the developer circulating portion 11 to form the stagnant portion 10, and a part of the developer is prevented from overflowing into the toner storage portion 6. It can be performed. When the amount of remaining toner is large, the toner existing between the toner blocking member 14 and the toner supply path 7 may cause blocking due to the weight of the toner. Can be avoided.

The configuration of the toner damming member 14 is such that a shaft is passed through the lower portion and a torsion coil spring is fixed to the shaft. Both arms of the torsion coil spring are fixed to the toner damming member 14 and the toner storage section 6, respectively. When the remaining amount of toner is large, the toner blocking member 14 is pressed against the lower end of the toner storage section 6 by the fixing member, so that the trajectory of the toner supply and stirring member 8 is not obstructed. On the other hand, when the remaining toner amount becomes smaller than the preset amount and the toner remaining amount detection sensor 15 outputs an output signal,
The lock is released by the movement of the fixing member, and the toner blocking member 14 is inverted by the repulsive force of the torsion coil spring. Alternatively, an electromagnetic clutch may be directly connected to a shaft below the toner blocking member 14 so that the toner blocking member 14 is inverted by an output signal of the toner remaining amount detection sensor 15.

Further, in accordance with an output signal of the toner remaining amount detecting sensor 15, the number of rotations of the toner replenishment stirring member 8 together with the toner blocking member 14 is reduced. Accordingly, a mechanism can be provided in which the toner is pushed into a narrow space between the toner damming member 14 and the toner replenishment path 7 and blocking that occurs is prevented.

FIG. 4 is a schematic structural view of a process cartridge having the developing device of the present invention. In the figure, 20
Denotes an entire process cartridge, 21 denotes a photosensitive member, 2
2 denotes a charging unit, 23 denotes a developing unit, and 24 denotes a cleaning unit. The developing unit 23 is a developing device according to the present invention, and is configured by integrally combining a plurality of components among the photoconductor 21, the charging unit 22, the cleaning unit 24, and the like. This process cartridge is detachable from the main body of an image forming apparatus such as a copying machine or a printer. The toner blocking member 14 is formed of P
It is made of a resin such as ET (polyethylene terephthalate) and is repelled many times by the toner replenishing and stirring member 8, which may cause deformation or the like. Since the entire cartridge can be replaced at the time of replacement, there is no need for maintenance work or the like.

[0013]

As described above, according to the present invention, the toner blocking member is inverted only when the toner remaining amount becomes smaller than the preset value and the toner remaining amount detecting sensor outputs an output signal. As a result, the toner can be held between the toner supply path and the toner circulating section, and sufficient toner can be present near the developer circulating section, and a part of the developer overflows into the toner storing section. This makes it possible to provide a developing device capable of preventing the occurrence of toner and taking in an appropriate amount of toner.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a developing device according to the present invention.

FIG. 2 is a diagram showing an appropriate arrangement of a developing device.

FIG. 3 is a diagram illustrating operations of a toner remaining amount detection sensor 15 and a toner damming member 14.

FIG. 4 is a schematic configuration diagram of a process cartridge having a developing device of the present invention.

FIG. 5 is a schematic configuration diagram of a conventional developing device.

FIG. 6 is a diagram illustrating a state in which toner consumption in a conventional developing device has advanced.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 developer carrying member 2 first developer regulating member 3 developer accommodating section 4 developer accommodating case 5 toner 6 toner accommodating section 7 toner replenishing path 8 toner replenishing stirring member 9 second developer regulating member 10 developer stagnation Unit 11 Developer Circulation Unit 12 Image Carrier 13 Developer Stripping Member 14 Toner Blocking Member 15 Toner Remaining Sensor 20 Process Cartridge 21 Photoconductor 22 Charging Unit 23 Developing Unit 24 Cleaning Unit

Claims (3)

[Claims] 1. A developer carrier having a magnetic field generating means therein for carrying and transporting a two-component developer containing a toner and a magnetic carrier, and a developer carrier carried by the developer carrier and transported. A first regulating member for regulating the amount of the developer, a developer accommodating portion for accommodating the developer scraped off by the first regulating member, and a developing device on the developer carrier more than the first regulating member. A second regulating member disposed on the upstream side in the developer conveying direction, and a toner having a toner supply and stirring member adjacent to the developer accommodating portion and stirring and supplying the toner to the developer carrier. A storage portion, wherein the developer blocked by the first regulating member forms a circulation portion in front of the second regulating member (upstream in the developer conveying direction), Movable by the sensor output signal of the sensor provided in the Developing apparatus is characterized by having a over dam member. 2. The developing device according to claim 1, wherein the number of rotations of the toner replenishment stirring member changes according to the sensor output signal. 3. A process in which the developing device according to claim 1 or 2 is integrally supported together with a photosensitive member and at least one means selected from a charging means and a cleaning means, and is configured to be detachable from an image forming apparatus main body. cartridge.