Patent Grant
8160464
1. Field of the Invention
The present invention relates to a developing apparatus including a developer carrying member for carrying a developer and a detecting member for detecting a developer amount by detecting the capacitance between the developer carrying member and the detecting member. This developing apparatus can be used for an image forming apparatus, which is preferably an electrophotography apparatus such as a printer or a copying machine.
2. Description of the Related Art
There is proposed a toner remaining amount detecting method of a capacitance detecting type as a method of detecting a remaining amount of developer (hereinafter referred to as toner) stored in the developing apparatus that is used for the image forming apparatus such as the electrophotography apparatus.
For instance, Japanese Patent Application Laid-Open No. 2002-244414 discloses a developing apparatus using a contact developing method illustrated in
A voltage induced in an antenna 78 as the detecting member for detecting developer amount is measured based on an alternating electric field formed by turning on and off the developing bias, such that toner amount between the antenna 78 and the developing roller 109 can be detected. In other words, a detector 102 is used to determine whether a space between the antenna 78 and the developing roller 109 is filled with toner, or whether the toner is consumed and does not fill the space.
When the detection of the toner remaining amount is performed, it is desirable to separate the developing roller from a photosensitive drum for eliminating influence of capacitance between them. As to this apparatus, the developing apparatus can swing around a swing center 106 using a contact and separate spring 107 and a contact and separate cam 108 illustrated in
On the other hand, as to a developing apparatus using jumping development, a method involving detecting the toner remaining amount by utilizing a change in capacitance is proposed, in which a developing bias that is an alternating electric field is applied to a developing sleeve as the developer carrying member.
In particular, as to a developing unit using toner that is nonmagnetic mono-component developer, it is common to provide a developing chamber with a supplying member for supplying developer to the developing sleeve. If the method of detecting the toner remaining amount through a change in capacitance is applied to a developing unit using the nonmagnetic mono-component developer, some problems will occur. For instance, since the supplying member exists, a space for housing the antenna is limited, so the capability of detecting the toner remaining amount may be deteriorated, or the toner may be blocked from being conveyed smoothly.
Therefore, as illustrated in
As to this jumping development, the developing sleeve that is the developer carrying member is opposed to the photosensitive drum with a predetermined gap between them. Therefore, it is not necessary that the developing apparatus can be made contact with and separate as illustrated in
Japanese Patent Application Laid-Open No. 2002-244414 discloses a structure in which the developing bias of the nonmagnetic mono-component contact developing apparatus is to be the DC bias, which is turned on and off periodically, and an alternating electric field generated in this way is used for detecting the toner remaining amount.
As for the developing apparatus using nonmagnetic mono-component developer, it is necessary to provide the developing chamber 23 with the supplying member 80. For this reason, some problems arise. For instance, a space for housing the antenna 78 is limited, so the capability of detecting the toner remaining amount may be deteriorated, or the toner may be blocked from being conveyed smoothly. In other words, it is disadvantageous to provide a special antenna 78 as a member for detecting the developer amount from a viewpoint of saving space and cost.
In addition, for a purpose of periodically turning on and off the DC bias as the developing bias without causing an image error, the developing roller is separated from the photosensitive drum during periods between printing of individual images (i.e., between so-called paper sheets) as illustrated in
However, a posture of the toner existing between the developing roller and the antenna when the developing roller contacts with the photosensitive drum during an image forming period is different from a posture of the toner existing between the developing roller and the antenna when the developing roller separates from the photosensitive drum during the period between paper sheets. In this way, since an abutting and separating operation is performed with different postures of the developing apparatus, the amount of toner existing between the developing roller and the antenna changes, which causes a problem that a voltage output varies so that a certain period of time is required before the voltage output becomes stable. In this way, according to the conventional structure, the developer amount is detected with different postures of the developing apparatus. Therefore, accuracy of detection cannot be stable, making it difficult to secure correct detection.
On the other hand, as illustrated in
However, when the developing bias having an AC component superimposed on a DC component was applied to the developing roller of the contact developing apparatus using the nonmagnetic mono-component developer, smear on a white background called fog appeared. Further, when the developing roller contacts with the photosensitive drum, hitting vibration occurred between them resulting in an undesirable hitting noise.
In addition, as described above with reference to
It is an object of the present invention to provide a developing apparatus that does not need a special antenna for detecting capacitance in the developing container and is advantageous for saving space and cost.
Another object of the present invention is to provide a developing apparatus in which a developer supplying member for supplying developer to the developer carrying member is used for detecting capacitance in the developing container.
Still another object of the present invention is to provide a developing apparatus capable of detecting capacitance correctly in the developing container.
Still another object of the present invention is to provide a developing apparatus capable of detecting a developer amount correctly even in the case where a posture of the developing apparatus changes.
Still another object of the present invention is to provide a developing apparatus having improved accuracy in detecting a developer amount in the developing container regardless of a variation in the developer amount.
Other objects and features of the present invention will be apparent from the detailed description below with reference to the attached drawings.
Now, a developing apparatus according to the present invention will be described with reference to the attached drawings by way of example.
The developing apparatus includes a developing container 3, a developer carrying member 1, a developer supplying member (developer amount detecting member) 2, and a developer regulating member 5. In
As the developer, nonmagnetic mono-component toner T having negative electrostatic charging property is used. The toner T becomes charged triboelectrically in the negative polarity upon developing, and a degree of compaction of the toner is 15%.
The degree of compaction of the toner was measured as follows.
As a measuring device, a powder tester (by HOSOKAWA MICRON CORPORATION) having a digital vibration meter (DIGITAL VIBRATION METER MODEL 1332 by SHOWA SOKKI CORPORATION) was used.
When the toner was measured, a 390 mesh sieve, a 200 mesh sieve, and a 100 mesh sieve were arranged in increasing order of opening size, that is, the 390 mesh sieve, the 200 mesh sieve, and the 100 mesh sieve were set on a shake table one on top of the other in order so that the 100 mesh sieve was the top layer.
Sample (toner) of 5 grams weighed precisely was applied on the set 100 mesh sieve. A displacement value detected by the digital vibration meter was adjusted to be 0.60 mm (peak-to-peak), and the vibration was applied for 15 seconds. After that, weight of the sample remaining on each of the sieves was measured, and the degree of compaction was obtained based on the equation below.
The sample to be measured had been left for 24 hours under the condition of temperature of 23 degrees centigrade and relative humidity of 60%, and the measurement was carried out under the condition of temperature of 23 degrees centigrade and relative humidity of 60%.
Degree of compaction (%)=(weight of remaining sample on 100 mesh sieve divided by 5 grams)×100+(weight of remaining sample on 200 mesh sieve divided by 5 grams)×60+(weight of remaining sample on 390 mesh sieve divided by 5 grams)×20.
As to the developing apparatus 4, the opening portion of the developing container 3 was disposed at the lower side, so self-weight of the toner T was exerted on the developing roller 1 and the supplying roller 2 disposed at the opening portion. This arrangement enables the developer to easily enter the supplying roller 2 and is preferable for detecting the developer amount in the developing container with high accuracy.
The developing roller 1 includes a conductive support member 1a and a semiconductive elastic rubber layer 1b containing conductive material around the conductive support member 1a, and is rotated in the direction indicated by the arrow A illustrated in
In addition, a resistance of the developing roller 1 of the embodiment of the present invention is 1×106 (ohms).
Here, a method of measuring resistance of the developing roller will be described.
The developing roller 1 is set to contact with an aluminum sleeve having a diameter of 30 mm by a contact load of 9.8 Newtons. The aluminum sleeve is rotated so that the developing roller 1 is rotated at 60 rpm following the aluminum sleeve. Next, a DC voltage of −50 volts is applied to the developing roller 1. On this occasion, a resistor of 10 kilo ohms is disposed on the ground side so that a voltage across the resistor is measured. Thus, the current is calculated, so a resistance of the developing roller 1 is calculated.
If the volume resistance of the developing roller 1 is larger than 1×109 (ohms), a voltage value of the developing bias on the surface of the developing roller is lowered so that a DC electric field in a developing region is decreased. Consequently, a developing efficiency is lowered, which causes a problem of a decrease in image density. Therefore, it is preferable to set the resistance of the developing roller 1 to a value equal to or smaller than 1×109 (ohms).
The supplying roller 2 that is the developer supplying member as well as the developer amount detecting member includes the conductive support member and a foam layer supported by the conductive support member. More specifically, an urethane foam layer 2b that is the foam layer made of open cell foam (open cell) in which air bubbles are communicated to each other is disposed around the core metal electrode 2a that is the conductive support member having an outer diameter of 5 (mm). The supplying roller 2 is rotated in the direction indicated by the arrow B illustrated in
In addition, a resistance of the supplying roller 2 of the embodiment of the present invention is 1×109 (ohms).
Here, a method of measuring a resistance of the supplying roller will be described.
The supplying roller 2 is set to contact with the aluminum sleeve having a diameter of 30 mm so that an inroad amount that will be described later becomes 1.5 mm. When this aluminum sleeve is rotated, the supplying roller 2 is rotated at 30 rpm following the aluminum sleeve. Next, a DC voltage of −50 volts is applied to the developing roller 1. On this occasion, a resistor of 10 kilo ohms is disposed on the ground side so that a voltage across the resistor is measured. Thus, the current is calculated, so a resistance of the supplying roller 2 is calculated.
A surface cell size of the supplying roller 2 is selected to be 50 to 1000 microns.
Here, the cell size means an average size of the foam cells in an arbitrary cross section. An area of a largest foam cell is measured from a magnified image in the arbitrary cross section, and a diameter corresponding to a perfect circle is calculated from the area so as to obtain the largest cell size. Foam cells having diameters equal to or smaller than a half of the largest cell size are removed as noises, and individual cell sizes are also calculated from areas of the remaining cells. An average value of the cell sizes is determined.
A surface aeration amount of the supplying roller 2 is selected to be 1.8 (liters per minute) or larger.
The “surface aeration amount” of the supplying roller 2 according to the embodiment of the present invention will be described in detail.
In this embodiment, the “aeration amount” is specified so that delivery and intake of the toner inside and outside the supplying roller is performed smoothly and that an equilibrium state between the inside and outside of the supplying roller can be obtained. The deliver and intake action of the toner that has become powder flow mixed with air is performed through a “surface layer” of the supplying roller, so it is important to directly specify an “aeration amount passing through the surface layer”.
First, the supplying roller 2 of the embodiment of the present invention is inserted in a measuring jig 18 as illustrated in
The measuring jig 18 in which the supplying roller 2 is inserted is attached to an aeration holder 19 as illustrated in
As illustrated in
A flowmeter 23 (KZ type aeration amount measuring instrument by DAIEI KAGAKUSEIKI SEISAKUSHO) and a differential pressure control valve 24 are disposed in the aeration tube 21.
The connection parts of the measuring jig 18, the aeration holder 19, the aeration tube 21, and the acrylic tubes 22a and 22b are sealed with tape or grease, so air flows in only through the exposed through hole of the measuring jig 18 when the decompression pump 20 evacuates the inside of the aeration tube 21.
The measurement of the “surface aeration amount” is performed as follows. First, as illustrated in
The airflow passing through the supplying roller 2 flows in from the surface of the urethane foam layer 2b disposed at the exposed through hole of the measuring jig 18, and passes through the inside of the urethane foam layer 2b. Then, it flows out of the surface of the urethane foam layer 2b disposed at the other through hole of the measuring jig 18.
The surface of the urethane foam layer 2b of the supplying roller 2 is usually different from the inside of the urethane foam layer 2b in many cases. For instance, if the supplying roller 2 is foamed in a mold to be formed, a skin layer having a rate of opening of surface cells different from cells of the inside may appear on the surface. In addition, there is another type of urethane foam layer 2b, which has a surface that is not a simple cylindrical surface but instead has intentional projections and depressions. The toner powder flow going in and out of the urethane foam layer 2b may be affected by the state of the surface, and it is difficult to capture the behavior thereof by only the measurement of the bulk aeration amount like JIS-L1096. Therefore, the embodiment of the present invention adopts the aeration amount measuring method of measuring the airflow flowing in and out of the surface of the urethane foam layer 2b as described above, which is used as a main parameter for realizing the equilibrium state of the toner powder flow described above (or a state close thereto). In other words, the inventors found that the parameter is important.
The developing roller 1 is rotated in the direction indicated by the arrow A as illustrated in
A rotation speed of the developing roller 1 is 130 (rpm), and a rotation speed of the supplying roller 2 is 100 (rpm). When the developing roller 1 and the supplying roller 2 rotate, the urethane foam layer 2b is deformed at the contact part contacting with the developing roller 1. On this occasion, the toner T retained on the surface or the inside of the urethane foam layer 2b of the supplying roller 2 is delivered from the surface of the urethane foam layer 2b when the urethane foam layer 2b is deformed, and a part of the toner T is transferred onto the surface of the developing roller 1. The toner T transferred onto the surface of the developing roller 1 is regulated to be uniform on the developing roller 1 by a regulating blade 5 that is the developer regulating member disposed downstream in the rotational direction of the developing roller 1 with respect to the contact part. In the process described above, the toner T is rubbed at the contact part between the developing roller 1 and the supplying roller 2 or a regulation part between the developing roller 1 and the regulating blade 5, so the toner T obtains a desired triboelectrification charge (negative charge in this embodiment). In addition, since the developing roller 1 and the supplying roller 2 are rotated in the opposite directions at their contact parts as illustrated in
Next, an operation of the developing apparatus according to the embodiment of the present invention when it is attached to the image forming apparatus will be described with reference to
In
This electrostatic latent image is developed by the developing apparatus 4, so it is visualized as a toner image. The toner is adhered to the exposed parts of the photosensitive drum, so it is developed reversely in the embodiment of the present invention.
The visualized toner image on the photosensitive drum 11 is transferred onto a recording medium 15 as a transferring material by a transferring roller 14. Untransferred remaining toner that remains on the photosensitive drum 11 is scratched by a cleaning blade 17 as a cleaning member and stored in a waste toner container 18. The cleaned photosensitive drum 11 repeats the action described above so as to form images. On the other hand, the toner image transferred onto a recording medium 6 is fixed permanently by a fixing device 16 and is delivered out of the apparatus.
In the embodiment of the present invention, the developing apparatus 4 is disposed as a cartridge 20 that integrally includes the photosensitive drum 11, the charging roller 12, the cleaning blade 17, and the waste toner container 18. The cartridge 20 is detachably mountable to a main body of the image forming apparatus. The user can open a window on the upper portion of the image forming apparatus in the direction indicated by the arrow G in
In the embodiment of the present invention, a DC voltage of −1000 volts is applied to the charging roller 12 so that the surface of the photosensitive drum 11 is charged at approximately −500 volts. This potential is referred to as a dark section potential Vd. During a period of time until the potential Vd of the photosensitive drum becomes stable, the developing apparatus 4 is maintained in the state where the developing roller 1 is separated from the photosensitive drum 11 as illustrated in
The developing apparatus has a force receiving portion 43 for receiving a force to move the developing container between a first position where the developing operation is performed by the developing roller and a second position where the developing operation is not performed. The force receiving portion 43 is provided to the predetermined position on the backside of the developing apparatus 4 of the cartridge. The force receiving portion 43 has a surface slip property necessary for rotating and contacting with the separation cam 42 and a hardness to resist deformation in the separate state where the largest force is exerted in the embodiment of the present invention.
When the separation cam 42 rotates, a cam surface of the cam 42 presses the force receiving portion 43 of the cartridge, so the developing apparatus 4 rotates around a swing center 40 as the rotation axis and overcomes a reaction force of a press spring 41 disposed between the developing apparatus 4 and the waste toner container 18. When the developing apparatus 4 swings, the developing roller 1 is moved from a contact position (
A posture position of the developing apparatus to make the developing roller 1 contact with the photosensitive drum 11 is referred to as a first position (developing position), and a posture position of the developing apparatus to make the developing roller 1 separate from the photosensitive drum 11 is referred to as a second position (non-developing position). In the second position, the developing apparatus does not perform the developing operation.
After the potential Vd of the photosensitive drum becomes stable, the photosensitive drum 11 is exposed by the laser beam from the laser optical device 13 as the exposure means, so the electrostatic latent image is formed on the surface thereof. A surface potential of the exposed part becomes approximately −100 volts. This potential is referred to as a light section potential V1. In addition, the developing roller 1 and the supplying roller 2 start to rotate at a predetermined timing driven by the drive means provided to the main body of the image forming apparatus and the drive transmission means (not shown), so as to prepare for the developing step of the electrostatic latent image. Before the developing step, the developing apparatus is moved from the second position to the first position. Therefore, the first position of the developing apparatus is the position where the developing roller 1 contacts with the photosensitive drum 11 so as to develop the electrostatic latent image formed on the photosensitive drum 11.
For instance, the separation cam 42 is rotated so that the drive means provided to the main body of the image forming apparatus makes the developing apparatus become the separation position (non-developing position) A as illustrated in
The first position of the developing apparatus is the position where the developing roller 1 abuts the photosensitive drum 11 in this way, so the electrostatic latent image formed on the photosensitive drum 11 is developed.
After the development of the electrostatic latent image is completed, i.e., during the post-rotation period of the photosensitive drum 11, the separation cam 42 rotates again to the separation position B. Thus, the separation cam 42 presses the force receiving portion 43 on the backside of the developing apparatus 4, so the developing apparatus 4 rotates around the swing center 40 as the rotation axis. The pressing force overcomes the reaction force of the press spring 41 disposed between the developing apparatus 4 and the waste toner container 18, so the developing roller 1 is separated from the photosensitive drum 11. In other words, the developing apparatus 4 is moved again to the second position.
At the same time, the rotation drive of the developing roller 1 and the supplying roller 2 is stopped, so the application of the developing bias of the developing roller 1 is stopped.
In the embodiment of the present invention, the capacitance between the developing roller and the supplying roller can be detected in the second position (
With reference to
In other words, even when the developing apparatus 4 swings between the first position and the second position, the contact electrode 25 and the contact electrode 26 as well as the contact electrode 27 and the contact electrode 28 remain in a contact state with each other. In the normal developing operation, the developing apparatus is in the first position, and a developing bias (DC voltage) is applied to the electrode 25 via the electrode 26. On this occasion, the same voltage as the developing bias is applied to the electrode 27 via the electrode 28. Therefore, the electrode 25 and the electrode 27 have the same potential in the developing operation, so no electric field is formed between the developing roller and the supplying roller. In this way, the capacitance detecting device 29 and the AC bias power supply 30 are switched to be connected to the developing bias power supply in the developing operation.
Next, as illustrated in
A voltage is induced at the conductive core metal 1a of the developing roller 1 by the toner remaining amount detecting bias applied to the core metal 2a, and this voltage is detected by the detector 29.
The second position where the developing operation is not performed, i.e., the state where the photosensitive drum 11 is separated from the developing roller 1 corresponds to the non-developing operation. More specifically, this state can be realized by a device operation, for instance, a period of time between paper sheets without image formation or during a period of time after the end of the image formation step until the recording medium 15 is delivered out of the image forming apparatus (a so-called post-rotation operation). Of course, it is possible to place the developing apparatus in the second position before the image formation and during a drum pre-rotation operation.
On this occasion, since the photosensitive drum 11 is separated from the developing roller 1 in this second position, smear on a white background called fog does not appear when an AC bias is applied as the toner remaining amount detecting bias. In addition, since the photosensitive drum 11 is separated from the developing roller 1, an undesirable hitting noise, due to impact and vibration between the developing roller and the photosensitive drum when they contact each other, is not generated.
Since the AC bias for detecting the toner remaining amount is applied from the conductive core metal 2a of the supplying roller 2 to the developing roller 1 that is used as a capacitance detecting antenna, it is possible to prevent an inhibition of conveying toner that may occur in the structure having a separate special antenna in the developing chamber.
The posture of the developing apparatus 4 is naturally changed in the abutting and separating operation between the photosensitive drum 11 and the developing roller 1, i.e., between the first position where the developing operation is performed and the second position where the developing operation is not performed as illustrated in
On this occasion, the AC bias for detecting the toner remaining amount is applied from the conductive core metal 2a of the supplying roller 2 to the developing roller 1 that is used as the capacitance detecting antenna in the developing apparatus 4 of the present embodiment, so a change in capacitance of the toner contained in the supplying roller 2 is measured. Therefore, the amount of toner contained in the supplying roller 2 does not change even if the posture of the developing apparatus 4 as well as the toner T moves along with the abutting and separating operation. In other words, the amount of toner between the developing roller 1 and the antenna (supplying roller) does not change, so the voltage output induced in the antenna does not change. Therefore, since the supplying roller 2 has the foam layer into which the toner can enter, the toner in the foam layer is hardly moved even if the posture of the developing apparatus changes. As a result, the voltage output does not change.
In addition, as to a nonmagnetic mono-component contact developing apparatus 4 according to the present embodiment, drive of the developing roller 1 and the supplying roller 2 is stopped during the detection of the capacitance of remaining toner, i.e., in the state where the developing roller 1 is separated from the photosensitive drum 11.
When the drive of the developing roller 1 and the supplying roller 2 is stopped, and the toner supply operation to the developing roller 1 and the removing operation of non-developing toner are stopped, the amount of toner contained in the supplying roller 2 becomes constant during the toner remaining amount detection, resulting in improvement of accuracy of the toner remaining amount detection.
In
For instance, some supplying rollers having different values of the surface aeration amount according to the embodiment of the present invention were made by changing a foam ratio of the foam layer of the supplying roller. Then, each of the supplying rollers is incorporated in the developing apparatus having the same structure as example 1, so as to compare with a result of the output of example 1 (the surface aeration amount of the supplying roller is 3.0 (liters per minute)).
As example 2, square dots and broken line of
As comparison example 1, circular dots and broken line of
As comparison example 2, dots of × and thin full line of
Comparing the embodiments 1 and 2 of the present invention with the comparison examples, it is understood that the output value has little change in comparison examples 1 and 2 from the start of use until the timing when a half or more of the toner T is consumed, and a change in the output appears when the amount of the toner T becomes substantially small.
Note that the aeration amount of the supplying roller described in Japanese Patent Application Laid-Open No. H11-288161 was measured by the method according to the embodiment of the present invention, and a result of the measurement was 0.3 to 1.3 (liters per minute).
In the measurement described above, a relationship between the capacitance output value of the developing apparatus 4 and the amount of toner contained in the supplying roller 2 according to example 1 was plotted as illustrated in
In addition, some supplying rollers having higher aeration amount values than the supplying roller of embodiment 1 of the present invention are made, so as to compare with the output result of the example 1 by using the developing apparatus having the same structure as example 1. A result of the comparison is illustrated in
As illustrated in
As described above, if the aeration amount of the supplying roller is selected appropriately, the amount of toner contained in the supplying roller increases. The amount of toner contained in the supplying roller decreases along with a decrease of the amount of toner stored in the developing container (see
Note that the toner in the supplying roller is discharged partially when the supplying roller starts to contact with the developing roller so that the supplying roller starts to be deformed. When the supplying roller finishes contacting with the developing roller, the deformation of the supplying roller is restored so that the part of the toner is sucked. In this way, the toner enters and goes out of the supplying roller. The amount of toner in the supplying roller is kept substantially in the equilibrium state as long as the amount of toner in the developing container does not change. In order to measure the output value of capacitance with high accuracy so as to determine the amount of toner in the supplying roller more precisely, it is preferable to measure while stopping the rotation of the supplying roller so that the toner does not enter into or exit from the supplying roller as described above.
The correlation between the amount of remaining toner in the developing apparatus and the amount of toner contained in the supplying roller illustrated in
In other words, if the toner has a degree of compaction equal to or lower than 30%, the toner can be used without any problem for realizing the equilibrium state of the toner entering and exiting the supplying roller, which is a feature of the present invention.
The amount of toner contained in the supplying roller has a correlation with the amount of toner in the toner container. Therefore, if the self-weight of the toner in the toner container is exerted on the supplying roller as it is, the correlation between the amount of remaining toner in the developing apparatus and the amount of toner contained in the supplying roller as illustrated in
The image forming apparatus 10 of the example described above has a structure in which the toner remaining amount detecting bias is applied to the supplying roller 2 so that the voltage induced in the developing roller 1 is detected by the disposed detector. However, it is possible to adopt another structure in which a remaining toner detecting bias is applied to the developing roller 1 so that a voltage induced in the supplying roller 2 is detected by a disposed detector, so a similar effect can be obtained.
Further, an example of other exemplary embodiments of the developing apparatus will be described with reference to the attached drawings. However, components and operations of the embodiment described below are similar to those of example 1, so the same reference numerals are used for omitting their description.
The developing cartridge made up of the developing apparatus 4 of
The developing apparatus having such a structure can employ the developing apparatus structural portion of the process cartridge described above in example 1 so that the same effect as example 1 can be obtained. In other words, the cartridge that is detachably mountable to the main body of the image forming apparatus may be the developing cartridge described above in this example or the process cartridge including the photosensitive drum described above in example 1.
According to the present invention, the developer supplying member for supplying the developer to the developer carrying member is also used for detecting the capacitance inside the developing container. Therefore, it is not necessary to provide a dedicated antenna for detecting the capacitance inside the developing container, thus providing advantages of saving space and cost. In addition, conveyance of the developer is not blocked while accurate detection can be performed stably so that accuracy of detecting a developer amount can be improved.
In addition, according to the present invention, the developer amount can be detected accurately even if a posture of the developing apparatus changes.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2007-172291, filed Jun. 29, 2007, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-172291 | Jun 2007 | JP | national |
This application is a divisional of U.S. patent application Ser. No. 12/144,786, filed Jun. 24, 2008.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5548382 | Koshi | Aug 1996 | A |
| 5946522 | Inami | Aug 1999 | A |
| 6275665 | Miyashiro | Aug 2001 | B1 |
| 6415127 | Yamamoto et al. | Jul 2002 | B1 |
| 6738593 | Kawamura et al. | May 2004 | B2 |
| 6909869 | Yamamoto et al. | Jun 2005 | B2 |
| 6965743 | Nakagawa et al. | Nov 2005 | B2 |
| 7006776 | Matsuzaka et al. | Feb 2006 | B2 |
| 7031629 | Kawamura et al. | Apr 2006 | B2 |
| 7254350 | Kawamura et al. | Aug 2007 | B2 |
| 20020150404 | Matsuzaka et al. | Oct 2002 | A1 |
| 20050008401 | Kawamura et al. | Jan 2005 | A1 |
| 20050260006 | Matsuda et al. | Nov 2005 | A1 |
| 20090003884 | Kawamura et al. | Jan 2009 | A1 |
| Number | Date | Country |
|---|---|---|
| 1055975 | Nov 2000 | EP |
| 1091262 | Apr 2001 | EP |
| 4-234777 | Aug 1992 | JP |
| 9-204095 | Aug 1997 | JP |
| 11-288161 | Oct 1999 | JP |
| 2002-244414 | Aug 2002 | JP |
| 2002-278412 | Sep 2002 | JP |
| 2003-43805 | Feb 2003 | JP |
| 2004-177765 | Jun 2004 | JP |
| 2007-86659 | Apr 2007 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20110206390 A1 | Aug 2011 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12144786 | Jun 2008 | US |
| Child | 13100622 | US |
