JP2986878B2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a developing device which is used in an electrophotographic recording device such as a laser beam printer and executes a developing process in an electrophotographic process. .

(Prior Art) As one of developing methods in an electrophotographic recording type developing process, a magnetic carrier is stored around a developer carrier roll in a storage container for storing a magnetic toner and a magnetic carrier. There is a method of mixing a magnetic toner and a magnetic carrier in the vicinity of an agent carrier roll.

FIG. 6 is a cross-sectional view showing an example of the configuration of a conventional developing device that performs development using such a developing method. In the figure, 1
Denotes a developer carrier roll, which is provided in parallel with a photosensitive drum (not shown). This developer carrier roll 1
Is a cylindrical sleeve 1a formed of a non-magnetic material and a magnet roll 1b provided inside the sleeve 1a.
The sleeve 1a rotates in the direction of arrow A, and the magnet roll 1b rotates in the direction of arrow B. The developer carrier roll 1 is located at the opening of the hopper 2 in a state where a part thereof is located in a storage container (hereinafter referred to as a hopper) 2. The hopper 2 stores a magnetic toner (hereinafter, referred to as toner) 3 and a magnetic carrier (hereinafter, referred to as carrier) 4. 5 is hopper 2
Is provided at the toner outlet 2a of the developer carrying roller 1. When the developer carrying roll 1 is rotated, the developer carrying roll 1
The amount of the toner 3 and the carrier 4 which are carried on the hopper 2 and guided to the outside of the hopper 2 are kept constant. Note that 6
Is an agitator for supplying the toner 3 to the vicinity of the developer carrier roll 1 and stirring the toner 3, and rotates in the direction of arrow C.

In such a developing device, the carrier 4 is arranged near the developer carrier roll 1 in an initial state as shown by a broken line in FIG. In addition, it adheres also around the developer carrier roll 1. Then, the toner 3 is mixed into the carrier 4 little by little and carried on the developer carrier roll 1.

However, with such a configuration, the carrier 4 moves as shown by an arrow D in FIG. 2 due to the rotation of the sleeve 1a, and is gradually dispersed throughout the hopper 2, and is carried on the developer carrier roll 1. The mixing ratio (toner concentration) of the toner 3 and the carrier 4 changes.

FIG. 7 shows the relationship between the toner concentration on the developer carrier roll 1 and the time (development time) during which the toner 3 carried and conveyed by the developer carrier roll 1 is in contact with the photosensitive drum. FIG. 8 shows the relationship between the toner density and the image density.

As can be seen from FIGS. 7 and 8, the toner density on the developer carrier roll 1 has a great influence on the recording characteristics. Therefore, if the toner density changes as described above, the recorded image will vary.

The carrier 4 also has a cleaning action on the sleeve 1a.
The above cleaning action becomes insufficient, and there is a possibility that blocking toner is formed on the sleeve 1a to cause deterioration in the image quality of the recorded image.

(Problems to be Solved by the Invention) As described above, in the conventional developing device, the carrier is merely arranged in the vicinity of the developer carrier roll, so that the carrier is dispersed by rotation of the developer carrier roll 1 or the like. As a result, there is a problem that the toner density changes, a blocking toner is formed on the developer carrier roll, and the density of the recorded image varies and the image quality deteriorates.

The present invention has been made in view of such circumstances, and an object of the present invention is to stably maintain a toner concentration and a carrier amount on a developer carrier roll to stably record a high-quality image. To provide a developing device capable of performing the following.

[Structure of the Invention] (Means for Solving the Problems) The invention according to claim (1) includes a storage container such as a hopper for storing a magnetic toner and a magnetic carrier,
A part is located in the storage container, and the magnetic toner and the magnetic carrier stored in the storage container are supported by magnetic force, and a developer carrier roll that rotates and conveys the magnetic toner and the magnetic carrier. In the developing device provided, the tip projects from the inner wall located above the developer carrier roll in the storage container so as to be separated from the bottom surface of the storage container, and the inner space of the storage container is filled with the developer. A first protrusion that divides into a mixed transport space between the surface of the carrier roll and another main storage space,
The bottom surface of the storage container is formed at a position facing the tip of the first protrusion, extends from a position higher than the tip of the first protrusion to a position immediately below the first protrusion, and the magnetic toner has its own weight. And an inclined surface which becomes lower as approaching the developer carrier roll at an angle of falling, and extends to a side closer to the developer carrier roll than immediately below a tip of the first protrusion continuously from the inclined surface. 2nd surface whose upper surface forms a substantially horizontal surface
And a protrusion.

The invention described in claim (2) provides the invention according to claim (1).
The surface of the first projecting portion facing the developer carrier roll in the invention described in (1) is a curved surface concentric with the peripheral surface of the developer carrier roll.

Further, the invention described in claim (3) provides the invention according to claim (1).
In addition to the invention described in the above, further provided is a toner supply unit that rotates in the main storage space, and conveys the magnetic toner stored in the main storage space above the inclined surface, and the toner supply unit An elastic member having a length in contact with the bottom of the storage container was provided.

(Operation) By taking the measures of the invention described in claim (1), the magnetic carrier is stored in the mixed transport space formed between the first projecting portion and the developer carrier roll. The magnetic toner existing in the main storage space falls under its own weight between the first protrusion and the inclined surface, and is placed on the upper surface of the second protrusion, and then the magnetic toner is rotated by rotation of the developer carrier roll. And, by the flow of the magnetic carrier, it is taken into the mixed transport space and mixed with the magnetic carrier. Therefore, since the magnetic carrier exists in the mixed transport space separated from the main storage space, and has a shape in which the supply of the magnetic toner from the main storage space to the mixed transport space is performed by dropping the magnetic toner by its own weight, The magnetic carrier is held in the vicinity of the developer carrier roll without diffusing into the main storage space, and the supply of the magnetic toner to the vicinity of the developer carrier roll is performed stably.

In addition, the inclined surface extends to a position immediately below the tip of the first projecting portion, and the upper surface of the second projecting portion is continuous with the inclined surface and closer to the developer carrier roll than immediately below the tip of the first projecting portion. Since it has a substantially horizontal surface extending to the main storage space and the mixing and conveying space, the opening surface is substantially vertical,
In addition, since there is a continuous surface on the inclined surface below the mixed transport space, the own weight of the magnetic toner does not act much on the mixed transport space. Therefore, the magnetic carrier and the magnetic toner stored in the mixed transport space are not applied with an unnecessarily large pressure, and the supply of the magnetic toner to the mixed transport space is stably performed. The occurrence of toner aggregation is prevented.

By taking the means of the invention described in claim (2), the volume of the mixed transport space in the invention described in claim (1) becomes substantially constant over the entire area, and while the mixed transport space is transported in the mixed transport space, Stirring of the magnetic toner and the magnetic carrier is stably performed.

By taking the means of the invention described in claim (3), the supply of the magnetic toner from the main storage space above the inclined surface in the invention described in claim (1) is rotated in the main storage space. The magnetic toner is more reliably sent to the upper side of the inclined surface by an elastic member provided in the toner supply unit and having a length in contact with the bottom of the storage container.

(Embodiment) Hereinafter, a first embodiment of a developing device of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a schematic configuration of the developing device.
The same parts as those in FIG. 6 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the figure, reference numeral 10 denotes a hopper as a storage container. In the hopper 10, a first protruding portion 10a having a bottom surface substantially along the peripheral surface of the sleeve 1a is formed on a wall portion on the upper side of the sleeve 1a. The bottom of the hopper 10
It comprises a first portion 10b having an arc-shaped cross section and a second portion 10c protruding from the first portion so as to cover the lower part of the sleeve 1a. A connecting portion between the first portion 10b and the second portion 10c is shown in FIG. It is shaped like a letter. Further, the inclination of the portion of the second portion 10c located on the side of the sleeve 1a is set to be equal to or larger than the angle at which the toner 3 easily falls due to its own weight (the angle of repose of the toner 3), and the upper surface is flat. The second protruding portion 10d is formed.

Here, the bottom surface of the first projecting portion 10a is spaced apart from the sleeve 1a by a predetermined distance, and forms a mixed transport space 11. It is desirable that the cross-sectional line S of the mixed transport space 11 be in the range of 1.0r ≦ S ≦ 10.0r, where r is the radius of the sleeve 1a.

In addition, the tip end (point S in the figure) of the first protrusion 10a has a predetermined interval with the bottom surface of the hopper 10. Further, the tip of the first protruding portion 10a (point S in the figure) is at the top (point P in the figure) of the connecting portion between the first portion 10b and the second portion 10c of the hopper 10.
Is set to a lower position.

Next, the operation of the present developing apparatus configured as described above will be described.

FIG. 2 is an enlarged view showing the periphery of the developer carrier roll 1 in FIG.

First, in the initial state, a predetermined amount of the carrier 4 and a predetermined amount of the toner 3 are mixed and stored in the mixing and transporting space 11 so that the toner concentration becomes a predetermined value (hereinafter, referred to as a “full”).
A mixture of the toner 3 and the carrier 4 stored in the mixing and conveying space 11 is referred to as a mixed layer). here,
In order to record a clear image, the volume of the mixed transport space 11 and the amount of the carrier 4 are optimally set, and the toner density is set at 20.
It is desirably about 90% (more preferably 40 to 70%). Replenishment toner 3 is stored in a space other than the mixing and conveying space 11 in the hopper 10 (working as a main storage space).

At this time, since the mixed transport space 11 is full, the toner 3 supplied from the hopper 10 to the mixed transport space 11 is
The first projection 10
is temporarily stored in a space (hereinafter, referred to as a sub-hopper) 12 formed between a and the second portion 10c at the bottom of the hopper 10. That is, the sub hopper 12 functions as a temporary storage unit. Here, the sub hopper 12 has a bottom portion that is located on the side of the sleeve 1a of the second portion 10c, but has an inclined portion that is located on the side of the sleeve 1a of the second portion 10c. Is set to be equal to or larger than the angle of repose of the toner 3, so that the bottom of the sub hopper 12 is an inclined surface having an angle equal to or larger than the angle of repose of the toner 3.

Here, when the developing operation is performed and the toner 3 in the mixed transport space 11 is consumed, the mixed transport space 11 has a margin.
Then, the toner 3 stored in the sub hopper 12 falls on the upper surface of the second protrusion 10d, is taken into the mixing and conveying space 11 by the rotation of the sleeve 1a and the magnetic force of the magnet roll 1b, and is mixed with the carrier 4. At this time, the mixing of the newly supplied toner 3 and the carrier 4 is mainly performed in a space indicated by a dashed line 11a in the figure (hereinafter, referred to as a mixing unit space). To toner 3
When the carrier 4 is transported, the toner 3
And the carrier 4 are mixed. That is, the mixing section space 11a functions as a mixing section.

The mixed layer thus obtained in the mixing section space 11a is mixed with the remaining space (hereinafter, referred to as a transport path space) 11b of the mixing and transporting space 11.
Is transported to the outside through the gap between the sleeve 1a and the blade 5. That is, the transport path space 11b functions as a transport path. The toner 3 and the carrier 4
In the stage, the toner is agitated by the movement at the stage of being conveyed in the conveyance path space 11b, and the toner density is brought closer to the optimum value.

As described above, in the present embodiment, the supply of the toner 3 from the hopper 10 to the developer carrier roll 1 is performed indirectly through the sub hopper 12, and the toner 3 is supplied from the hopper 10 to the developer carrier roll 1. Since the developer carrier roll 1 has a structure in which the toner 3 is taken in by the magnetic force of the magnet roll instead of extruding the toner 3, the toner 3 is always supplied to the developer carrier roll 1 stably. Will be Further, the mixing of the toner 3 and the carrier 4 and the transport of the mixed layer are performed in the mixing section space 11a and the transport path space 11b which are separated from the space where the toner 3 for replenishment of the hopper 10 is stored. Therefore, the carrier 4 does not move from the mixing section space 11a and the transport path space 11b to another space in the hopper 10, and the dispersion of the carrier 4 does not occur.

Further, in this embodiment, the tip of the first protruding portion 10a (point S in the figure) is higher than the top (point P in the figure) of the joint between the first portion 10b and the second portion 10c of the hopper 10. It is set to a lower position. In addition, the inclination angle of the portion of the second portion 10c of the hopper 10 which is the bottom of the sub hopper 12 is
The angle of repose is set at or above the angle of repose. Therefore, the toner 3 is not forcibly pushed into the sub hopper 12 by the agitator 6, and the toner is supplied to the sub hopper 12 only by its own weight. Thus, the supply of the toner 3 to the mixed transport space 11 can be performed more stably.

Further, the second protrusion 10d is provided, and the toner 3 placed on the upper surface of the second protrusion 10d is mixed with the carrier 4, so that the toner 3 is mixed by rotation of the sleeve 1a and magnetic force of the magnet roll 1b. Intake into the transfer space 11 can be reliably performed. The second protrusion
10d also has the effect of preventing the mixed layer from flowing back.

Further, since the bottom surface of the first projecting portion 10a has a shape substantially along the peripheral surface of the sleeve 1a, the interval between the sleeve 1a and the first projecting portion 10a is substantially constant. But the volume is almost the same. Thereby, the stirring of the mixed layer when being transported in the mixed transport space 11 is stably performed in the entire area of the mixed transport space 11, and the toner concentration can be optimized stably.

By these various actions, the amount of the toner 3 and the amount of the carrier 4 in the mixed transport space 11 can be made constant, and the toner density on the developing sleeve 1a can be always kept constant. Accordingly, the image density becomes stable, and recording can always be performed under optimum conditions, so that a clear image can be obtained. In addition, the diameter of the sleeve 1 is
An experiment was conducted with a developing device having a developing width of 18 mm and a developing width of 260 mm with an amount of the carrier 4 of 10 g.
The degree was kept constant.

By the way, the agitator 6 generally has a configuration as shown in FIG. In the figure, reference numerals 6a and 6b denote toner conveying members in which both ends of the rod are vertically bent in the same direction,
They are arranged to face each other with the cylindrical shaft 6c interposed therebetween. Thus, the agitator 6 rotates in the direction of the arrow C in the hopper 10 as shown in FIG. 1, so that the toner 3 stored in the hopper 3 is stirred and the toner 3 is supplied to the sub hopper 12. .

However, in the agitator 6 having the configuration shown in FIG. 3, when the amount of the toner 3 stored in the hopper 10 becomes small, the toner conveying ability of the toner conveying members 6a and 6b decreases, and the supply of the toner 3 becomes defective. It may be. this is,
The provision of the first projecting portion 10a as in the present application causes a problem particularly when the opening for supplying the toner near the developer carrier roll 1 is small.

Hereinafter, a second embodiment of the present invention will be described in which means for preventing such a problem are taken. FIG. 4 is a sectional view showing a schematic configuration of the developing device, and FIG. 5 is a perspective view showing a configuration of an agitator.

As shown in FIGS. 4 and 5, a hopper is mounted on an agitator 6 similar to that shown in FIGS. 1 and 3.
Elastic members 21 and 22 having a length to be in contact with the first portion 10b (the bottom surface of the hopper 10) are added. The elastic members 21 and 22 are formed by impregnating rubber into nylon, for example.

The agitator 6 has elastic members 21 and 22
When contacting the first portion 10b, the elastic members 21 and 22 are arranged so as to be curved in the opposite direction to the rotation direction of the agitator 6 as shown in FIG.

Thus, by configuring the agitator 6 as described above, the toner 3 located at the bottom of the hopper 10 is scraped out toward the sub-hopper 12 by the elastic members 21 and 22, and the amount of toner remaining in the hopper 10 is reduced. In this case, the supply of the toner 3 to the sub hopper 12 is performed accurately. Accordingly, the supply of the toner 3 from the sub hopper 12 to the mixing section space 11a is stably performed, and the fluctuation of the toner density can be prevented.

Further, as shown in FIG. 4, the length between the axis of the shaft 6c of the agitator 6 and the tip of the elastic members 21 and 22 is larger than the length from the axis of the shaft 6c to the first portion 10b of the hopper 10. As a result, the ends of the elastic members 21 and 22 project through the upper part of the sub hopper 12 and pass through.
Is agitated. Thereby, aggregation of the toner in this portion is prevented. At this time, the difference (projection amount) between the length from the axis of the shaft 6c to the tip of the elastic members 21 and 22 and the length from the axis of the shaft 6c to the first portion 10b of the hopper 10 is, for example, 3 mm. However, this depends on the shape and dimensions of the hopper 10, the agitator 6, and the agitator 6
The optimum value changes depending on the rotation speed of the motor.

Further, the elastic members 21 and 22 are connected to the first portion 10b of the hopper 10.
When the elastic member 21 and 22 abut against the first portion 10b of the hopper 10, an increase in the rotational load of the agitator 6 can be minimized. Thereby, an increase in torque required for a motor (not shown) for rotating the agitator 6 is not caused, and a small and inexpensive motor can be used. When the elastic members 21 and 22 do not bend,
Alternatively, as compared with the case where the elastic members 21 and 22 bend in the same direction as the rotation direction of the agitator 6, the elastic members 21 and 22 contact the first portion 10b of the hopper 10 more accurately.
Even if the processing accuracy of 22 is low, a sufficient effect is achieved.

The present invention is not limited to the above embodiments. For example, in the above embodiment, the tip of the first protruding portion 10a (point S in the drawing) is higher than the top (point P in the drawing) of the connecting portion between the first portion 10b and the second portion 10c of the hopper 10. The lower position prevents the toner 3 from being forcibly supplied by the agitator 6. However, for example, when the agitator 6 is not provided, the above-described configuration is not necessary.

In addition, various modifications can be made without departing from the spirit of the present invention.

[Effect of the Invention] According to the invention described in claim (1), a storage container for storing magnetic toner and a magnetic carrier, and the magnetic toner partly located in the storage container and stored in the storage container And a developer carrier that carries the magnetic carrier by magnetic force and rotates to transport the magnetic toner and the magnetic carrier.
The tip protrudes from the inner wall of the storage container located above the developer carrier roll so as to be separated from the bottom surface of the storage container, and the inner space of the storage container is separated from the surface of the developer carrier roll. A first projecting portion which is divided into a mixed transport space and a main storage space other than the first projecting portion, formed at a position opposite to a tip of the first projecting portion on the bottom surface of the storage container; From the first position
An inclined surface that extends to a position immediately below the protrusion and that becomes lower as the magnetic toner comes closer to the developer carrier roll at an angle at which the magnetic toner falls under its own weight; and a portion immediately below the tip of the first protrusion that is continuous with the inclined surface. And a second protruding portion whose upper surface forms a substantially horizontal surface extending to a side closer to the developer carrier roll than the developer carrier roll, so that the toner concentration and the carrier amount on the developer carrier roll are kept constant and stable. Thus, a developing device capable of recording a high-quality image is obtained.

Further, according to the invention described in claim (2), the surface of the first protrusion in the invention described in claim (1), which faces the developer carrier roll, is provided on the developer carrier roll. Since the curved surface is concentric with the peripheral surface, the magnetic toner and the magnetic carrier can be stably agitated while being transported through the mixed transport space, in addition to the effect of the invention described in claim (1). In addition, the toner concentration on the developer carrier roll can be further optimized.

According to the invention described in claim (3), in addition to the invention described in claim (1), the magnetic toner that rotates in the main storage space and transfers the magnetic toner stored in the main storage space to the main storage space. The effect of the invention according to the above-mentioned (1), wherein the toner supply means is provided above the inclined surface, and the elastic member having a length in contact with the bottom of the storage container is provided in the toner supply means. In addition, it is possible to more reliably supply the magnetic toner above the inclined surface.

[Brief description of the drawings]

1 and 2 are views for explaining a developing device according to a first embodiment of the present invention. FIG. 1 is a sectional view showing a schematic configuration, and FIG. FIGS. 3 to 5 are views showing a developing device according to a second embodiment of the present invention in an enlarged view showing the periphery of the body roll 1, and FIG. 3 is a diagram showing a general shape of an agitator. FIG. 4 is a cross-sectional view showing a schematic configuration of the developing device of the present embodiment, FIG. 5 is a perspective view showing a configuration of an agitator of the present embodiment, and FIGS. FIG. DESCRIPTION OF SYMBOLS 1 ... Developer roll, 1a ... Sleeve, 1b ... Magnet body, 3 ... Toner 4, ... Carrier, 5 ... Blade, 6 ... Agitator, 6a, 6b ... Toner conveyance member, 6c
…… Shaft, 10 …… Hopper, 10a …… First protrusion, 10d ……
Second protruding portion, 11: mixed transport space, 11a: mixing portion space, 11b: transport path space, 12: sub hopper, 21, 22 ...
... elastic member.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaaki Ishikawa 3-1-1 Asahigaoka, Hino-shi, Tokyo Inside Toshiba Hino Plant Co., Ltd. (72) Michihisa Iguchi 3-1-1 Asahigaoka, Hino-shi, Tokyo Inside Toshiba Hino Factory (72) Inventor Hiroshi Hashizume 3-1-1 Asahigaoka, Hino City, Tokyo Inside Toshiba Hino Factory Co., Ltd. (72) Yasuo Fujii 3-1-1 Asahigaoka, Hino City, Tokyo Inside Toshiba Hino Plant (72) Inventor Tetsuya Nakamura 3-1-1 Asahigaoka, Hino-shi, Tokyo Inside the Toshiba Hino Plant (72) Inventor Hirotaka Fukuyama 3-1-1 Asahigaoka, Hino-shi, Tokyo Inside the Toshiba Hino Factory (72) Inventor Seiji Arai 3-1-1 Asahigaoka, Hino-shi, Tokyo Inside the Toshiba Hino Factory (72) Inventor Koichiro Sato 3-1-1 Asahigaoka, Hino-shi, Tokyo Inside the Toshiba Hino Plant (72) Inventor Toshio Takagi 3-1-1 Asahigaoka, Hino-shi, Tokyo Inside the Toshiba Hino Plant (72) Inventor Nisina Shuji 1014 Miyahara-cho, Kofu City, Yamanashi Prefecture Inside Yamanashi Electronics Co., Ltd. (72) Inventor Jiro Fukasawa 1014 Miyahara-cho, Kofu City, Yamanashi Prefecture Inside Yamanashi Electronics Industry Co., Ltd. Address Yamanashi Electronics Industry Co., Ltd. (72) Inventor Seiichi Koizumi 1014 Miyaharacho, Kofu City, Yamanashi Prefecture Yamanashi Electronics Industry Co., Ltd. (56) References JP-A-61-53677 (JP, A) JP-A-62- 289874 (JP, A) JP-A-63-213877 (JP, A) JP-A-62-153880 (JP, A) JP-A-60-143456 (JP, U)

Claims (3)

(57) [Claims] A storage container for storing a magnetic toner and a magnetic carrier, a part of which is located in the storage container, and the magnetic toner and the magnetic carrier stored in the storage container are carried by magnetic force and rotated. A developer carrier roll for transporting the magnetic toner and the magnetic carrier, wherein a top of the developer carrier roll in the storage container is separated from a bottom surface of the storage container so that a leading end is separated from the bottom surface of the storage container. A first protruding portion projecting from an inner wall located at a position, dividing the internal space of the storage container into a mixed transport space between the surface of the developer carrier roll and another main storage space, The bottom surface is formed at a position facing the tip of the first protrusion, extends from a position higher than the tip of the first protrusion to a position directly below the first protrusion, and An inclined surface that becomes lower as it approaches the developer carrier roll at an angle at which the developer carrier falls under its own weight; and a side closer to the developer carrier roll than immediately below the tip of the first protrusion continuously to the inclined surface. And a second protruding portion whose upper surface forms a substantially horizontal surface extending to the second protruding portion. 2. The device according to claim 1, wherein the surface of the first projecting portion facing the developer carrier roll has a curved surface concentric with the peripheral surface of the developer carrier roll. Developing device. 3. A toner supply means which rotates in the main storage space and conveys the magnetic toner stored in the main storage space above the inclined surface, wherein the toner supply means includes a storage container. 2. The developing device according to claim 1, further comprising an elastic member having a length in contact with the bottom of the developing device.