JP2000221782A - Developing device and transporting member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of excellently measuring the toner ratio in the developer by a sensor. SOLUTION: This developing device is, allowed to incorporate an agitating chamber extended in the length direction for containing the developer including the toner and carriers, a transporting member 10 disposed in the agitating chamber extending in the above length direction of the agitating chamber that a wing shape member 30 is attached thereon, and the sensor 14 arranged adjacently in the agitating chamber for measuring the toner ratio in the above developer contained in the agitating chamber. In this case, the device is allowed to dispose the wing shape transporting means 10 made narrower than another section in the sensor 14 vicinity so that the developer transported in the above agitating chamber, is allowed to stay on the position opposite to the sensor 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly to an image forming apparatus using a two-component developer and having a toner density control mechanism using a magnetic permeability sensor. The present invention relates to a developing device and a developer conveying member used in the present invention.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, miniaturization and
Cost reduction is required, and accordingly, a developing device constituting an image forming apparatus is also required to be small. From such a viewpoint, for example, Japanese Patent Application Laid-Open No. 9-106
Japanese Patent Publication No. 169 discloses that two developing members 32 each having a blade-like member 30 as shown in FIGS. 3 and 4 are provided in a developing device. This wing-like member 30
A compact structure is provided alongside the developing sleeve on the horizontal plane to transport and circulate the developer while mixing and stirring it in different directions. In addition, a magnetic permeability sensor that outputs a voltage using the magnetic permeability of the developer is provided during the transport of the developer, and toner is supplied based on a difference between the reference voltage and the average value of the detection voltage. And a mechanism for controlling the toner density.

[0003]

However, the developing device as described above has the following problems. The developer detected by the sensor is conveyed by the wing-like member as described above. At this time, the developer conveyed by the wing-like member is conveyed in a wavy manner. FIG. 4 shows a perspective view of a conventional stirring member 30. The agitating blades 40 are arranged in the transport device 10 so as to be inclined with respect to the central axis in the unloading direction so that the toner can be unloaded from the toner supply unit to the toner discharge unit. . The magnetic permeability sensor (not shown) is disposed apart from the central shaft 42 so as to be within the stirring area of the stirring blade 40. The toner is discharged over the entire stirring area toward the toner discharge port by the shearing force of each stirring blade. FIG. 5 shows the output value of the magnetic permeability sensor at this time. Since the output of the magnetic permeability sensor (not shown) is disposed in the stirring area of each stirring blade, when the above-described conveying member is used, the developer is conveyed only in one direction. On the front side F of 40, the developer is in a dense state, and on the rear side R, it is in a rough state. Therefore, every time the blade member passes through the magnetic permeability sensor, the density of the developer is generated. Accordingly, a ripple having a peak H and a valley L as shown in FIG. The peak H of the ripple corresponds to a state where the developer is dense, and the trough L corresponds to a state where the developer is coarse. When the amount of developer measured by the sensor changes, the change appears in the sensor output.
The sensor output is an output having a large so-called ripple. An output having a large ripple is not preferable in terms of stability of the measurement accuracy of the sensor, and as a result, an inconvenience such as a change in image density occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a developing device capable of satisfactorily measuring the ratio of toner in a developer by using a sensor and a conveying member used therefor. It is in.

[0005]

In order to solve the above-mentioned problems, the invention according to claim 1 comprises a stirring chamber extending in a longitudinal direction in which a developer containing a toner and a carrier is accommodated, and the stirring chamber. And measuring the proportion of toner in the developer that is disposed adjacent to the stirring chamber and that is accommodated in the stirring chamber and that is adjacent to the stirring chamber and that extends in the longitudinal direction of the stirring chamber. And a sensor having a width shorter than other portions in the vicinity of the sensor so that the developer conveyed in the stirring chamber stays at a position facing the sensor. Is a developing device having a shape member. According to a second aspect of the present invention, in the developing device, a toner supply unit is provided at one end of the stirring chamber, and the sensor is provided on a side of the toner supply unit opposite to the longitudinal direction of the stirring chamber. is there. Furthermore, the invention according to claim 3 is characterized in that the transport member has a first blade member having a first stirring region centered on a central axis, and a second stirring region smaller than the first blade member. And a second blade member having the following. Also, in the invention according to claim 4, the sensor is configured such that the first stirring region and the second stirring region are arranged with respect to the center axis.
Is a developing device disposed between the stirring regions. Further, the invention according to claim 5 has a central axis, and a plurality of stirring blades projecting obliquely in a radial direction from the central axis, wherein the stirring blade includes a first blade member, A second blade member, wherein the first blade member has a first stirring region centered on a central axis, and the second blade member is Is a conveying member having a small second stirring area.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described by taking a developing device and an image forming unit applied to a copying machine as an example.
The present invention can be applied not only to a copying machine but also to various printers for facsimile machines, personal computers, and other image forming apparatuses.

Hereinafter, the present invention will be described with reference to the drawings. FIG.
1 shows an image forming apparatus 2 used in the present invention. The image forming apparatus 2 includes a photoconductor 4 and a developing device 5,
The developing device 5 is provided with a developing sleeve 6 for supplying toner to the photoreceptor 4 and two conveying members 8 and 10 extending along the developing sleeve 6 on a horizontal plane. The conveying members 8 and 10 are separated by a partition plate 12, and the conveying path is divided. Further, a magnetic permeability sensor 14 for measuring the magnetic permeability of the two-component developer is provided at an intermediate position of the transport member 10, and controls the toner density based on the detection data of the magnetic permeability sensor 14. It is supposed to do. A toner bottle 16 is provided beside the conveying member 10 and extends along the conveying member 10. The toner bottle 16 is supplied upstream on the conveying direction of the conveying member 10 based on the control of the toner density. The image forming operation of the image forming apparatus 2 will be briefly described. First, the photosensitive member 4 is neutralized by neutralizing light, and the surface potential is averaged to a reference potential. Next, after being charged by the charger 18, the image portion which is exposed at the exposure portion and is not irradiated with light maintains the surface potential, so that the toner on the developing sleeve 6 adheres to the image portion. The photoreceptor 4 on which the toner image is formed is rotated, and a transfer sheet is fed from a paper supply unit (not shown) at a timing such that the leading end of the sheet coincides with the leading end of the image in the transfer device 21. The toner on the four surfaces is transferred to the transfer paper. The transfer belt is sent to a fixing unit (not shown), and the toner is fused to the transfer paper by heat and pressure, and is discharged as a copy. On the other hand, the residual toner remaining on the photoreceptor 4 is scraped off by the cleaning blade 20, and then the residual charge is removed by the discharging light, leaving no toner, and the process proceeds to the next image forming step again.

In the present invention, a conveying member 10 disposed in the stirring chamber on the side of the toner bottle 16 and a conveying member 8 disposed in the stirring chamber on the side of the developing sleeve are used in the conveying device. These transport members 8 and 10 are driven so as to transport the developer in directions opposite to each other with respect to the longitudinal direction. These stirring chambers are defined by a partition plate 12 provided between the transport members 8 and 10.
10 define respective areas of toner to be conveyed. Describing the transport of the developer, first, toner is supplied to the upstream side of the transport device 10 from the toner supply box 16 and mixed with the developer remaining in the developing device 5, and the developer is transported to the back side of the paper. It is conveyed toward. A magnetic permeability sensor 14 is provided in the middle of the transport path of the transport member 10, and the density of the mixture of the toner newly supplied from the toner box and the developer remaining before is used for the purpose. It is configured to measure whether the concentration is appropriate.

Further, the developer is conveyed from the toner supply port provided on the front side toward the paper surface to the back side, and
The developer is supplied to a stirring chamber in which the conveying member 8 is disposed via a rear communication path formed between the developing device and a wall on the rear side of the drawing. The developer is supplied to the stirring chamber provided with the conveying member 8 through the inner communication path. Thereafter, the developer is transported by the transport member 8 to the front side toward the paper surface,
The toner is supplied to the developing sleeve anew, and the developer whose density is adjusted is sent. In addition, a part of the developer conveyed by the conveying member 8 is returned to the stirring chamber provided with the conveying member 10 through the front communication path provided between the walls on the front side of the drawing device. Is configured. The transport member 10 described above is provided with a plurality of stirring blades 30 around a central axis 32. The transport speed of the developer in the stirring chamber provided with the transport member 10 is detected by a magnetic permeability sensor 14 for detecting the toner density, and the toner density is sufficiently controlled according to the magnetic characteristics of the carrier. It is configured to be able to.

FIG. 2 shows the configuration of the transport member 10 of the present invention. The transport member 10 includes a central shaft 32 and a plurality of stirring blades 30 disposed around the central shaft 32.
And The stirring blade 30 has at least two types of blades 30a and 30b, and the first blade 30a
Has a first stirring area, and the second stirring blade 30b has
The configuration has a stirring area smaller in the radial direction from the central axis than the first stirring area. The stirring blade 30b having the second stirring region is provided so as to be adjacent to the magnetic permeability sensor 14 described above. By providing the stirring blade 30b having the second stirring region adjacent to the magnetic permeability sensor 14 as described above, the stirring operation of the stirring blade near the magnetic permeability sensor 14 is eliminated, and the output ripple of the magnetic permeability sensor 14 is reduced. Can be done. In order to form the second stirring region, the diameter of the stirring blade itself can be reduced as in the case of the stirring blade 30b. However, as shown in FIG. 2, the stirring blade 30c is connected to the stirring blade 30a. While keeping the same diameter or small diameter as above, eccentrically adjust the center axis 3
2 so that the stirring blades do not reach the area of the magnetic permeability sensor 14. These stirring blades 30
a, 30b, and 30c are arranged in the transport device 5 so as to be inclined toward the discharge direction with respect to the central axis so that the toner can be discharged from the toner supply unit to the toner discharge unit. . This inclination angle can be set as appropriate, but is preferably set to approximately 30 °.

Referring to FIG. 2, the toner supply control of the present invention will be further described. In the present invention, the toner concentration control is performed based on the data detected by the magnetic permeability sensor 14. FIG. 2 shows that the magnetic permeability sensor 14 is disposed apart from the central axis of the stirring member 10.
It is preferable that the detection output of the magnetic permeability sensor 14 is always stabilized so that there is no output ripple as described with reference to FIG. Therefore, in the present invention, the toner supply port is located on the upstream side in the transport direction, and the magnetic permeability sensor 14 is arranged closer to the transport member 10 on the downstream side in the transport direction. With this arrangement, when the sensor is disposed near the toner replenishing unit, if toner is replenished from the toner replenishing unit, an increase in the toner ratio due to the toner replenishment is immediately reflected in the sensor output. By outputting to the sensor with insufficient stirring, it is possible to prevent the sensor output from reaching the target value before reaching the target toner ratio after stirring. That is, with this configuration, the toner supply amount is insufficient,
It is possible to prevent the inconvenience that the toner ratio in the developing unit becomes lower than the target.

Furthermore, in the present invention, the magnetic permeability sensor 14 does not include the stirrable area 2 of the plurality of stirring blades 30b adjacent to the magnetic permeability sensor 14, but determines whether or not proper toner supply has been performed. Is required to be disposed in an area where the developer is conveyed. To do so, in the present invention, the portion of the stirring blade 30b adjacent to the magnetic permeability sensor 14 is shortened as shown in FIG. 2, but this magnetic permeability sensor 14 is adjacent to the magnetic permeability sensor 14. The agitating blade 30a, which is not used, is disposed apart from the central shaft 32 within a range where the developer can be agitated. By doing so, it is possible to reduce the ripple by eliminating the density of the developer near the magnetic permeability sensor 14 while maintaining the necessary toner conveying speed in the longitudinal direction near the magnetic permeability sensor 14. In addition, the above-described stirring blades 30b and 30c
As shown in (1), it is not always necessary to provide only the sensor adjacent to the magnetic permeability sensor 14. The output ripple of the magnetic permeability sensor 14 can be appropriately adjusted, and an appropriate developer transport speed can be obtained. If possible, a plurality of stirring blades 30b, 30c can be used. In addition, it is not always necessary to use the stirring blades 30b and 30c in combination. For example, the stirring blades 30c are provided in the entire region in the longitudinal direction of the transporting member 10, and the transporting region does not reach the stirring blades 30c during stirring. Permeability sensor 14
May be arranged. However, it is not preferable that all the stirring blades have a small diameter as indicated by 30b in FIG. 2 because an area not conveyed by the stirring member 10 is generated in the conveyance area. That is, in the present invention, as described above, the stirring device 10
By shortening a part of the plurality of agitating blades so that the agitating blades do not reach the detection area of the magnetic permeability sensor 14, good toner conveyance is ensured, and the magnetic permeability sensor 14 This enables stabilization.

FIGS. 3 and 4 are diagrams showing a stirring blade used in a conventional stirring device as a comparative example. The stirring blade 40 configured as shown in FIG. 3 stirs the toner in the vicinity of the magnetic permeability sensor (not shown) in the same manner as in the other areas, so that an output ripple is generated in the magnetic permeability sensor. , And density unevenness occurs in the obtained copy image.

[0014]

As described above, in the developing device according to the first aspect, in the developing device having the sensor for measuring the ratio of the toner in the developer, the developer is generated when the developer is conveyed by the blade member of the conveying device. The density of the developer can be reduced by shortening the width of the blade member at the position where the sensor is installed and retaining the developer. As a result, the ripple in the output of the magnetic permeability sensor can be reduced, and the measurement accuracy of the sensor can be improved. Further, in the developing device described in claim 2, the position of the sensor is arranged as far downstream as possible from the toner replenishing unit, so that the toner is sufficiently mixed when the toner is replenished from the toner replenishing unit. The problem that the increase in the toner ratio due to replenishment is reflected in the sensor output at an early stage to prevent the apparent target toner ratio from being reached, and that the toner ratio in the developing unit is reduced due to insufficient toner replenishment. Can be solved. Further, in the developing device according to claim 3,
Using a developing device having a first blade member having a first stirring region around a central axis and a second blade member having a second stirring region smaller than the first stirring region,
It is possible to reduce the output ripple due to the occurrence of the developer density in the vicinity of the magnetic permeability sensor 14 and to stabilize the control of the toner density. Further, in the developing device according to the fourth aspect, the sensor is disposed between the first stirring area and the second stirring area with respect to the central axis, so that the sensor is not located at a portion where the stirring blade does not reach. The developer can be reliably detected by arranging it at a portion where the developer moves by any one of the stirring blades. Furthermore, the transport member according to claim 5, comprising a central axis, and a plurality of stirring blades projecting from the central axis inclining in a radial direction,
Each of the stirring blades has a first stirring region, and the second blade member has a first blade member having a second stirring region smaller than the first stirring region, and a second blade. And a developing device that can perform good toner density control as described above by using such a conveying member.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus using a developing device and a transport device of the present invention.

FIG. 2 is a schematic sectional view showing the toner conveying member shown in FIG.

FIG. 3 is a schematic sectional view showing a conventional toner conveying member.

FIG. 4 is a schematic perspective view showing the toner conveying member shown in FIG.

FIG. 5 is a diagram illustrating an output ripple of a magnetic permeability sensor provided in a conventional toner conveying device.

[Explanation of symbols]

 2 Image Forming Apparatus 4 Photoconductor 5 Developing Device 6 Developing Sleeve 8, 10 Conveying Member 12 Partition Plate 14 Magnetic Permeability Sensor 16 Toner Bottle 18 Charger 20 Cleaning Blade 21 Transfer Device 30, 30a, 30b, 30c, 40 Stirring Blade 32, 42 Central axis F Front side R Back side H Ripple peak L Ripple trough

Claims (5)

[Claims] An agitating chamber extending in a longitudinal direction in which a developer containing a toner and a carrier is accommodated; and a conveying member provided in the agitating chamber, extending in the longitudinal direction of the agitating chamber, and having a blade-like member attached thereto. And a sensor arranged adjacent to the stirring chamber and configured to measure a ratio of toner in the developer contained in the stirring chamber, wherein the transport member is transported in the stirring chamber. A developing device, comprising: a blade-like member having a shorter width than other portions near the sensor so that the developer stays at a position facing the sensor. 2. The developing device according to claim 1, wherein a toner replenishing unit is disposed at one end of the stirring chamber, and the sensor is disposed on a side of the toner replenishing unit opposite to the longitudinal direction of the stirring chamber. A developing device. 3. The developing device according to claim 1, wherein the conveying member has a first blade member having a first stirring area centered on a central axis, and A second blade member having a small second stirring area. 4. The developing device according to claim 3, wherein the sensor is disposed between the first stirring area and the second stirring area with respect to the central axis. Developing device. 5. A stirring blade having a center axis and a plurality of stirring blades projecting from the center axis so as to be inclined in a radial direction, wherein the stirring blade has a first blade member and a second blade member. And the first blade member has a first stirring region around the center axis, and the second blade member defines a second stirring region smaller than the first stirring region. A conveying member having: