JPH10142927A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device by which the specified amount of developer is always retained at a position opposed to a sensor so as to excellently measure tone ratio in the developer by means of the sensor. SOLUTION: The first chamber 15 of a stirring chamber 13 is longitudinal, and the developer inside the chamber 15 is carried by a first spiral shaft 9. The toner sensor 60 is arranged on a central part in the longitudinal direction of the chamber 15. As to the spiral shaft; vertical stirring blade 46 is provided at a position a little closer to the downstream side of a toner carrying direction from the arranged position of the sensor 60. The developer is hardly moved by the blade 46, so that the developer is retained on the upstream side of the blade 46. That is, the amount of the developer inside the measuring area of the sensor 60 is always secured to the specified amount. Therefore, the output of the sensor 60 becomes the one with less ripple so as to be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device,
In particular, the present invention relates to a developing device that uses a developer containing a toner and a carrier.

[0002]

2. Description of the Related Art One of developers for developing an electrostatic image is a two-component developer. The two-component developer contains a toner and a carrier, and is used by stirring them in a developing device. For this reason, conventionally, there has been known a developing device provided with a spiral shaft for stirring the developer (toner and carrier) in a stirring chamber and transporting the developer in a predetermined direction. During development, the spiral shaft is rotated to transport the toner to the developing sleeve while stirring the toner.

By the way, when the development is performed, the toner is consumed, but the amount of the carrier in the stirring chamber does not change. For this reason, the ratio between the toner and the carrier in the stirring chamber changes, so that the toner must be replenished sequentially according to the consumption amount. Usually, the ratio between the toner and the carrier is measured by a sensor, and toner is supplied based on the output of the sensor.

[0004]

As the above-mentioned sensor, a magnetic sensor for detecting a change in magnetic flux density is usually used. Incidentally, the developer detected by the sensor is transported by the spiral shaft as described above. The developer conveyed by the spiral shaft is conveyed in a pulsed manner while being guided by the spiral blade. For this reason, when the sensor is arranged at a predetermined position of the developing device, when the developer passes through the measurement area of the sensor, the amount of the developer changes in a pulsating manner.

When the amount of the developer to be measured by the sensor changes, the change appears in the output of the sensor, and the sensor output becomes a so-called large ripple output. An output having a large ripple is not preferable in terms of stability of the measurement accuracy of the sensor. SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved developing device so that the ratio of toner in a developer can be favorably measured by a sensor.

[0006]

According to the first aspect of the present invention,
A stirring chamber extending in a longitudinal direction in which a developer containing a toner and a carrier is accommodated, a rotation shaft provided in the stirring chamber and extending in the length direction of the stirring chamber, and a spiral blade extending in a spiral shape along the rotation axis. A spiral shaft for transporting the developer from one end of the stirring chamber to the other end, and a sensor arranged in relation to the stirring chamber for measuring a toner ratio in the developer contained in the stirring chamber In the developing device including the developer, the spiral shaft is rotated around the downstream side in the developer conveying direction with respect to the sensor arrangement position so that the developer conveyed in the stirring chamber stays at the position facing the sensor. A vertical stirring blade is provided to fill the gap between the spiral blades in the axial direction.

According to a second aspect of the present invention, in the developing device according to the first aspect, the sensor is provided at a substantially central portion in a longitudinal direction of the stirring chamber, and a toner supply section is provided at one end of the stirring chamber. It is characterized by the following. In the configuration of the first aspect, the vertical stirring blade is provided slightly downstream of the sensor arrangement position when viewed in the developer transport direction. Therefore, the movement of the toner is hindered by the vertical stirring blade, and the toner conveyance speed is reduced in this portion. Therefore, the toner stays on the upstream side of the vertical stirring blade.

In a state where a fixed amount of toner stays, there is little change in the quantity of the object to be measured by the sensor, and the sensor output is an output with little ripple. Therefore, the toner ratio in the developer can be stably measured. In the configuration of claim 2,
A sensor is provided at a substantially central portion in the longitudinal direction of the stirring chamber, which is not far from toner supply. Therefore, when toner is replenished from the toner replenishment unit, an increase in the toner ratio due to the replenishment of the toner is reflected on the sensor output relatively quickly.

Further, since the sensor is located at a distance of about half the longitudinal direction of the stirring chamber from the toner replenishing unit, the toner in the developer reaching the sensor-facing position may be uneven due to insufficient stirring. Absent.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a developing device and an image forming unit applied to a copying machine will be described as an example. However, the developing device and the image forming unit of the present invention are not limited to a copying machine, but may be a facsimile machine, The invention is also applicable to various printers for personal computers and other image forming apparatuses.

FIG. 1 is a perspective view showing a state in which an image forming unit 1 according to an embodiment of the present invention is being mounted on a multi-function copying machine 2. The multi-function copying machine 2 is a device that operates not only as a normal copying machine but also as a facsimile or a printer. The image forming unit 1 is mounted / removed by opening the front cover 3 provided on the front of the copying machine 2. The image forming unit 1
For example, when the photosensitive drum included in the unit 1 reaches the end of its service life, it is removed and a new image forming unit 1 is removed.
Is attached.

FIG. 2 is a schematic sectional view showing the internal configuration of the image forming unit 1. The image forming unit 1 includes a photosensitive drum 4 for forming an electrostatic image and a photosensitive drum 4.
And a developing device 5 for developing the electrostatic image formed on the peripheral surface with toner. The photosensitive drum 4 and the developing device 5 are provided at both ends by a pair of side plates 6 (only one side plate, that is, only the back side plate 6 is shown in the figure), that is, a front end portion in FIG. And the rear end are held and combined so as to have a predetermined positional relationship, and are integrated as one unit.

The developing device 5 includes a toner cartridge 7,
A sub spiral shaft 8, a first spiral shaft 9, a second spiral shaft 10 and a developing sleeve 11 are provided, and are surrounded by a casing 12. Each of these members is a member that is elongated in the direction perpendicular to the paper surface. The photosensitive drum 4 is also a member that is elongated in the direction perpendicular to the plane of the drawing. The toner cartridge 7 is detachable from the image forming unit 1. When the toner in the toner cartridge 7 runs out, the toner cartridge 7 is replaced with a new one. The toner in the toner cartridge 7 is dropped on the sub spiral shaft 8 under a predetermined control. In the auxiliary spiral shaft 8, the toner dropped from the toner cartridge 7 and the existing developer (toner and carrier) are mixed and sent to the first spiral shaft 9 as described later.
Then, the developer is supplied to the first spiral shaft 9 as described later.
The toner is sufficiently stirred and frictionally charged by the second spiral shaft 10 and adheres to the peripheral surface of the developing sleeve 11 so as to be in a so-called spike state.

The toner in the developer on the peripheral surface of the developing sleeve 11 moves to the photosensitive drum 4 by the action of static electricity, and develops the electrostatic image formed on the photosensitive drum 4. FIG.
FIG. 3 is a plan view of the developing device 5 viewed along an arrow AA in FIG. 2. Referring to FIG. 3, the developing device 5 includes a casing 12
A stirring chamber 13 is provided. The stirring chamber 13 is partitioned into a first chamber 15 and a second chamber 16 by a partition plate 14. First chamber 15 and second chamber 16
Is a chamber elongated in the front-rear direction (left-right direction in FIG. 3) of the developing device 5. The first chamber 15 and the second chamber 16 are notched at the front and rear ends of the partition plate 14, and are connected by moving ports 29 and 28. The first chamber 15 has a first spiral shaft 9, and the second chamber 16 has a second spiral shaft 1.
0 is arranged. The first spiral shaft 9 and the second spiral shaft 10 are arranged in parallel and constitute a main stirring mechanism. Further, adjacent to the second spiral shaft 10, the second
A developing sleeve 11 is arranged in parallel with the spiral shaft 10.

The developing device 5 according to this embodiment is further provided with a sub-chamber 17 formed by the casing 12. The sub chamber 17 is a small chamber provided adjacent to the first chamber 15 and provided on the front side (the left side in FIG. 3) of the developing device 5. Above the sub chamber 17, a toner supply port 37 for supplying toner is formed. A sub-spiral shaft 18 is accommodated in the sub-chamber 17 in parallel with the first spiral shaft 9.

A partition plate 1 is provided between the first chamber 15 and the sub-chamber 17.
It is divided by nine. The partition plate 19 has an inlet 20 and an outlet 21. The entrance 20 is the first room 1
5 is an opening for moving the developer from the sub-chamber 17 to the sub-chamber 17,
The outlet 21 is an opening through which the developer in the sub chamber 17 moves to the first chamber 15. In this embodiment, the inlet 20 is made larger than the outlet 21.

The casing 12 is attached to the sub-spiral shaft 18.
A gear 22 disposed outside the front of the vehicle is connected. The first spiral shaft 9 is connected to a gear 23 disposed outside the front of the casing 12. The gear 22 and the gear 23 are meshed. At the rear end of the first spiral shaft 9, a gear 24 arranged rearward and outside of the casing 12 is provided.
Are connected. A gear 25 disposed on the rear outside of the casing 12 is connected to the second spiral shaft 10, and a gear 26 disposed on the rear outside of the casing 12 is also connected to the developing sleeve 11. And gear 2
The gears 4 and 25 mesh with each other, and the gears 25 and 26 mesh with each other via a transmission gear 27.

As a result, when a driving force is applied to the gear 22 connected to the auxiliary spiral shaft 18, the auxiliary spiral shaft 1
8, the first spiral shaft 9, the second spiral shaft 10, and the developing sleeve 11 rotate in conjunction with each other. FIG. 4 shows the flow of the developer in the developing device 5 in a plan view.
Referring to FIG. 3 and FIG. 4, the developer is conveyed while being stirred by the first spiral shaft 9 as shown in the first chamber 15. Then, when it comes to the rear end of the first chamber 15, it moves to the second chamber 16 as shown by the moving port 28. Then, in the second chamber 16, it is conveyed while being agitated by the second spiral shaft 10 as shown in FIG. At this time, the second
The toner and the carrier, which are frictionally charged by agitation, are attached to the peripheral surface of the developing sleeve 11 in a so-called spike state on the developing sleeve 11 adjacent to the spiral shaft 10.

The developer conveyed to the front end of the second chamber 16 moves to the first chamber 15 through a transfer port 29 as shown by で.
A part of the developer transferred to the first chamber is conveyed in the first chamber 15 as indicated by a symbol, and a part of the developer enters the sub-chamber 17 from the entrance 20 as indicated by the symbol. In the sub chamber 17, the toner supplied from the toner supply port 37 is mixed with the developer by the sub spiral shaft. Then, the first chamber 16 is conveyed as shown in FIG.
Sent to Then, the developer is merged with the developer sent along the path, and is conveyed while being stirred in the first chamber 15 by the first spiral shaft 9 as shown by.

FIG. 5 is a perspective view of a portion around the sub-chamber 17 of the developing device 15. The auxiliary spiral shaft 8 includes a rotating shaft 31 extending in the front-rear direction of the developing device 5, a spiral blade 32 protruding in a spiral shape along the rotating shaft from the front side to the rear side of the rotating shaft 31, and a front end of the rotating shaft 31. The rotary shaft 31 includes a take-in blade 33 provided at a portion thereof, a sending blade 34 provided at a rear end of the rotary shaft 31, and flanges 35 and 36 formed at a front end and a rear end of the rotary shaft 31.
Note that the intake blade 33 can be omitted.

The developer that has entered the sub-chamber 17 from the inlet 20 is stirred by the intake blade 33 and then conveyed while being stirred by the spiral blade 32. A toner supply port 37 is formed on the sub chamber 17, and toner is supplied from the toner cartridge 7 (see FIG. 1) through the toner supply port 37. The replenished toner is mixed with the developer contained in the sub chamber 17. In other words, prior to the stirring by the main stirring mechanism, the preceding stage of stirring (mixing) is performed.

The sub-chamber 17 is controlled by the delivery blades 37.
To the first chamber 15 through the outlet 25. The entrance 20 and the exit 21 are different in size as described above, and the exit is smaller than the entrance 20. For example, in this embodiment, the width A of the entrance 20 is 25
mm, and the width B of the outlet 21 is 15 mm. As a result, a constant amount of developer always stays in the sub-chamber 17, and the toner supplied from the toner supply port 37 is efficiently mixed with the developer accumulated in the sub-chamber 17. Can be.

The first spiral shaft 9 also has a rotating shaft 41, a spiral blade 42, a take-in blade 43, and a flange 45, like the sub-spiral shaft. Similarly, the second
The spiral shaft 10 also includes a rotating shaft 51, a spiral blade 5
2. It has a delivery blade 54 and a flange 55 (see also FIG. 3). By the way, the pitch P1 of the spiral blade 42 of the first spiral shaft 9 and the pitch P1 of the second spiral shaft 10
P2 of spiral blade 52 and sub-spiral shaft 8
Are set to different values from the pitch P3 of the spiral blade 32. Specifically, spiral blade 4
2, the pitch P1 of the spiral blade 52 is 8 mm, and the pitch P3 of the spiral blade 32 is 1 mm.
0 mm. Pitch P1 of spiral blade 42
Is larger than the pitch P2 of the spiral blade 52.
This is because the vertical stirring blades 46 are scattered on the first spiral shaft 9. The vertical stirring blade 46 is a blade protruding so as to fill a gap between the spiral blades 42 in the direction of the rotation shaft 41. By dispersing the vertical stirring blades 46,
The developer stays in front of the vertical stirring blades 46, and the vertical stirring blades 46 increase the toner and carrier stirring efficiency. On the other hand, since the developer is retained, the transport speed of the developer is reduced.

By the way, referring to FIG. 4, the transport speed of the developer in the path must be substantially equal to the transport rate of the developer in the path. Because if the transport speed of one route is slow and the transport speed of the other route is fast,
This is because the developer is biased in one of the chambers.
Therefore, in this embodiment, the pitches P1 and P2 of the two spiral blades are set such that the transport speed of the first spiral shaft 9 on which the vertical stirring blades 46 are scattered is equal to the transport speed of the second spiral shaft 10. ing.

The pitch P2 of the spiral blades on the second spiral shaft 10 is set to a pitch at which the developer is supplied to the developing sleeve 11 at a predetermined supply ratio. Further, the pitch P3 of the spiral blades 32 of the auxiliary spiral shaft 18 is set so that the developer and the supplied toner can be mixed well, and the amount of the developer sent from the outlet 21 to the first chamber 15 becomes an appropriate amount. It has a great pitch.

In addition, any of the spiral blades 32, 4
2, 52 also have a diameter φ of 20 mm in this embodiment.
It is common in. The delivery blade 54 of the second spiral shaft 10 is shaped so that the developer can be successfully delivered from the second chamber 16 to the first chamber 15. The intake blade 42 of the first spiral shaft 9 develops the developer into the first chamber 15. The shape is such that the agent can be taken in and a part thereof can be sent to the sub chamber 17 through the inlet 20.

Next, description will be made again with reference to FIG. The developing device 5 is provided with a toner sensor 60 disposed outside the casing 12. The toner sensor 60 can be provided inside the casing 12. The toner sensor 60 is, for example, a sensor that measures a change in magnetic flux density, and measures the ratio of the toner in the developer.
That is, assuming that the toner amount is T and the total amount of the toner and the carrier is D, the sensor is for measuring T / D. When T / D is a predetermined value, good development can be performed. Based on the output of the toner sensor 60 for measuring T / D,
The toner supply amount supplied from the toner supply port 37 is controlled. If necessary, the rotational speeds of the auxiliary spiral shaft 8, the first spiral shaft 9, the second spiral shaft 10, and the developing sleeve 11, which rotate in conjunction with each other, are controlled.

Since the toner sensor 60 is an important sensor for measuring the T / D of the developer, it is preferable that the detection output is always stable. Therefore, in this embodiment, the toner sensor 60 is disposed substantially at the center of the developing device 5 in the longitudinal direction. The reason for this is that if the toner sensor 60 is arranged rearward in the longitudinal direction, there is a disadvantage that it takes time until the toner supplied to the sub-chamber 17 is detected by the toner sensor. The time lag between the so-called toner supply and the output of the toner sensor 60 increases. On the other hand, if the toner sensor 60 is disposed on the front side in the longitudinal direction, the T / D may be measured in a state where the replenished toner is not uniformly mixed.

Therefore, as described above, the toner sensor 60 is disposed substantially at the center in the longitudinal direction. Another feature of this embodiment is that the vertical stirring blades 46 of the first spiral shaft 9 move the toner sensor 6 when viewed in the developer conveying direction.
That is, it is provided slightly downstream of 0. When the vertical stirring blades 46 are provided, the transport speed of the developer is reduced as described above, and the developer stays in front thereof. Therefore, when the vertical stirring blade 46 is provided slightly downstream of the toner sensor 60, the developer always stays in the first chamber 15 at a position facing the toner sensor 60. That is, the amount of the developer in the portion facing the toner sensor 60 does not fluctuate greatly in accordance with the rotation of the spiral blade 32, and a predetermined amount of the developer always remains. Therefore, the toner sensor 6
The output ripple of 0 (the rate at which the maximum value and the minimum value of the output signal fluctuate with time) can be reduced. Therefore, the output of the toner sensor 60 is stabilized,
, The amount of toner replenishment can be controlled satisfactorily based on the output.

Although the description of one embodiment of the present invention is as described above, the present invention is not limited to the above embodiment, and various modifications can be made within the scope described in the claims. It is.

[0031]

According to the present invention, in a developing device using a developer containing a toner and a carrier, it is possible to provide a developing device capable of accurately measuring the ratio of the toner in the developer. As a result, using a developer having an appropriate toner content,
A developing device having excellent developing performance can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which an image forming unit according to an embodiment of the present invention is being mounted on a multi-function copying machine.

FIG. 2 is a schematic cross-sectional view illustrating an internal configuration of an image forming unit.

FIG. 3 is a plan view of the developing device as viewed along arrow AA in FIG. 2;

FIG. 4 is a diagram illustrating a flow of a developer in the developing device when viewed in plan.

FIG. 5 is a perspective view of a portion centering on a sub-chamber of the developing device.

[Explanation of symbols]

 Reference Signs List 5 developing device 9 first spiral shaft 11 developing sleeve 52 spiral blade 37 toner supply port 46 vertical stirring blade 60 toner sensor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naoyuki Ishida 1-2-28 Tamazuki, Chuo-ku, Osaka, Osaka Inside Mita Industries Co., Ltd. (72) Inventor Masahiko Miyazaki 1-2-2, Tamazuki, Chuo-ku, Osaka, Osaka No. 28 Inside Mita Kogyo Co., Ltd. (72) Inventor Tetsuya Ichigotani 1-2-28 Tamatsukuri, Chuo-ku, Osaka-shi, Osaka No. 28 Inside Mita Kogyo Co., Ltd. Shoji Hirano 1-2-2 Takuma-zo, Chuo-ku, Osaka, Osaka No. 28 Inside Mita Industrial Co., Ltd.

Claims (2)

[Claims] An agitating chamber that extends in a longitudinal direction and accommodates a developer containing a toner and a carrier; a rotating shaft provided in the agitating chamber and extending in a longitudinal direction of the agitating chamber; A spiral shaft for projecting the developer from one end of the stirring chamber to the other end having a protruding spiral blade; and a toner shaft in the developer housed in the stirring chamber disposed in relation to the stirring chamber. In a developing device including a sensor for measurement, the spiral shaft has a downstream side in a conveying direction of the developer with respect to the sensor arrangement position so that the developer conveyed in the stirring chamber stays at a position facing the sensor. A vertical stirring blade that is provided in the vicinity of the side to fill a gap between the spiral blades in the direction of the rotation axis. 2. The developing device according to claim 1, wherein the sensor is provided at a substantially central portion in a longitudinal direction of the stirring chamber, and a toner supply section is provided at one end of the stirring chamber. .