JP5153306B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a main body of an image forming apparatus including a developer carrier that carries a developer and a detection member that detects the amount of developer. This image forming apparatus is preferably used in an electrophotographic apparatus such as a printer or a copying machine.

  Conventionally, in a developing device used in an image forming apparatus such as an electrophotographic apparatus, an apparatus as shown in FIG. 17 is known as an apparatus for detecting the remaining amount of developer (hereinafter referred to as toner).

  In the developing device shown in FIG. 17, magnetic one-component toner (magnetic toner) is accommodated in the developer container 71. The accommodated toner is sent to the developing chamber 73 by the toner feeding member 72. In the developing chamber 73, a sleeve 75 that includes a fixed magnet 74 and rotates in the direction of the arrow shown is provided so as to face the photosensitive drum 76.

  In order to coat the toner sent into the developing chamber 73 on the sleeve 75, an elastic blade 77 is provided. The sleeve 75 and the photosensitive drum 76 have an interval of 50 μm to 500 μm, and a toner having a thickness smaller than the interval is coated on the sleeve 75 by the elastic blade 77. A developing bias in which alternating current is superimposed on direct current is applied to the sleeve 75 by the developing bias power source 101, and so-called jumping development is performed from the sleeve 75 to the photosensitive drum 76.

  A toner remaining amount detection method in the developing device 70 described above will be described. Reference numeral 78 denotes an antenna made of a metal rod such as stainless steel provided in parallel with the sleeve 75. When a developing bias in which alternating current is superimposed on direct current is applied to the sleeve 75, a voltage depending on the capacitance between the sleeve 75 and the antenna 78 is induced in the antenna 78.

  In a state where a sufficient amount of toner is stored and the space between the antenna 78 and the sleeve 75 is filled with toner, and in a state where the toner is consumed and the space between the sleeve 75 and the antenna 78 is not filled with toner, electrostatic The capacity is different. Therefore, since the voltage induced in the antenna 78 is also different, the remaining amount of toner can be detected by detecting this voltage value with the detector 102.

  On the other hand, in a developing device in which a nonmagnetic one-component developer (nonmagnetic toner) is used, an application member is generally provided in the developing chamber 73. When the method for detecting the remaining amount of toner using the change in capacitance described above is applied to a developing device using such non-magnetic toner, a space for providing an antenna for the coating member becomes narrower, Problems such as obstructing conveyance occur.

  In order to solve this problem, a configuration in which a supply member 80 for supplying toner to the sleeve 75 is provided as shown in FIG. The supply member 80 is provided with a urethane sponge layer (foamed layer) so as to surround the circumference of the conductive metal support 79.

  According to this configuration, when the toner is applied to the sleeve 75 by the supply member 80, an AC voltage is applied to the sleeve 75, thereby inducing a voltage corresponding to the amount of toner on the conductive support 79. The remaining amount of toner can be detected by the voltage (Patent Document 1).

On the other hand, the structure of the foam layer of the supply member 80 is not limited to the structure disclosed in Patent Document 1. Patent Document 2 discloses a supply member that includes a foam layer having an air flow rate of 10 to 40 cc / cm ² / sec, prevents toner deterioration, and obtains good image quality. However, Patent Document 2 does not disclose a configuration for detecting the remaining amount of toner.
JP-A-4-234777 JP-A-11-288161

  However, the following problems occur in the conventional image forming apparatus configured to detect the remaining amount of the developer.

  In a toner remaining amount detecting device (developer amount measuring device) using an antenna, a dedicated antenna is required to detect the remaining amount of toner. Therefore, the provision of a dedicated antenna causes space limitations and further increases costs.

  Further, when the remaining amount of toner is detected using an antenna, it is very difficult to accurately detect the remaining amount of toner. This is because the amount of toner existing between the antenna and the sleeve is detected, so that the remaining amount of toner in the entire toner container cannot always be detected accurately.

  For example, when the developing device is not used (when the toner is sufficiently filled in the container) and when the toner is consumed to some extent, the amount of toner existing between the antenna and the sleeve is the same as when not used In each of these, the remaining amount detection value output value shows the same value. That is, in the toner remaining amount detection method using an antenna, it is difficult to accurately detect the toner remaining amount in the toner container. In order to solve this, a method of providing another antenna in the toner container is conceivable.

  On the other hand, according to Patent Document 1, a dedicated antenna is not required, and space and cost are advantageous, but detection accuracy is not sufficient. In addition, in the toner remaining amount detecting device as in Patent Document 1, the toner remaining amount detecting method using the change in the electrostatic capacity described above was performed using the supply member made of urethane sponge of Patent Document 2.

  However, the change in detection output at a time when a sufficient amount of toner is present in the toner container is unstable, and it is difficult to detect an accurate toner amount. Furthermore, if the amount of toner in the toner container does not become small, it is difficult to detect the remaining amount of toner, and an image defect called low density due to toner shortage may occur.

  Therefore, a contact developing device is provided with a coating member made of urethane sponge, and an AC electric field is applied to the developing roller to induce a voltage on the conductive support in accordance with the amount of toner. Quantity detection was performed.

  However, when a developing bias in which alternating current is superimposed on direct current is applied to the developing roller in the contact developing device, a white background stain called fog occurs. Furthermore, since the developing roller and the photosensitive drum are in contact with each other, they hit each other and vibrate, resulting in an unpleasant impact sound.

  On the contrary, when a bias in which alternating current is superimposed on direct current is applied to an application member made of urethane sponge and a metal support, a toner coat abnormality on the developing roller is observed.

That is, it is not preferable to apply a bias in which an alternating current is superimposed on a direct current during a printing operation because it causes image defects and noise. Therefore, in order to accurately detect the remaining amount of toner while avoiding these problems, a method of providing a remaining amount detection timing after the printing operation can be considered. However, when the user requests continuous printing, providing the toner remaining amount detection timing for each sheet reduces the printing efficiency of the image forming apparatus.

  However, in order to avoid these problems, if the remaining amount of toner is not detected during continuous printing, the amount of toner consumed in the toner container cannot be grasped, and the toner runs out during continuous printing. It may cause a situation.

  Therefore, the present invention detects the remaining amount of toner in the toner container even under various usage conditions by using the antenna remaining amount detection method based on the antenna system of the contact developing device, which supplementarily uses the number of image dots and the number of printed sheets. An object of the present invention is to provide an image forming apparatus that can perform the above-described process.

In order to achieve the above object, in the present invention, a developer container having an opening and containing a developer and a first conductive support, and carrying the developer in the opening. And a second conductive support provided inside the developer container in contact with the developer carrier, and a foam layer provided around the second conductive support, A rotatable developer supply member for supplying the developer to the developer carrier, and an image dot counting means for counting the number of image dots formed on the image carrier, during non-image formation An image provided with a developer amount measuring device for measuring the developer amount in the developing container by detecting a capacitance between the first conductive support and the second conductive support. In the forming apparatus, the result of comparing the value of the number of image dots and the value measured by the developer amount measuring device Et al., Interrupted image formed during continuous printing, characterized in that it comprises a control means for causing the measurement operation to the developer amount measuring device.

Also, a developer container having an opening and containing a developer, a first conductive support, a developer carrier that carries the developer in the opening, and the developer carrying inside the developer container A second conductive support provided in contact with the body, and a foam layer provided around the second conductive support, wherein the developer carrying member is supplied with the developer. A movable developer supply member; and a printed sheet number storage unit for storing the number of sheets printed by the image forming apparatus , wherein the first conductive support and the second conductive support are formed during non-image formation. In the image forming apparatus provided with a developer amount measuring device that measures the developer amount in the developer container by detecting the capacitance between the print number storage means and the developer amount measurement Image formation during continuous printing based on comparison of measured values from the device Interrupted, characterized in that it comprises a control means for causing the measurement operation to the developer amount measuring device.

  According to the present invention, a dedicated antenna for detecting a capacitance in a toner container by using a toner supply member that supplies toner to the toner carrier in order to detect the capacitance in the toner container. This is advantageous in terms of space and cost.

  Further, it is possible to detect the remaining amount of toner stably and accurately without hindering toner conveyance, and the accuracy of detecting the remaining amount of toner can be improved.

  In addition, according to the present invention, the remaining amount of toner is roughly detected based on the number of image dots or the number of prints while forming an image in a print state. As a result, even when continuous printing is performed in a state where the toner in the toner container is consumed and the remaining amount is reduced, the remaining amount of toner can be detected without losing the printing productivity as much as possible. The remaining amount of toner can be accurately indicated.

  The best mode for carrying out the present invention will be exemplarily described in detail below based on the embodiments with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.

[First embodiment]
The image forming apparatus according to the first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows a schematic configuration of the developing device 4 in the present embodiment. The developing device 4 includes a developing container 3, a developing roller (developer carrier) 1, a supply roller (developer supply member) 2, and a regulating blade 5. The developing container 3 contains toner T that is a non-magnetic one-component developer. The developing roller 1 is installed in the opening of the developing container 3 and is supported by the developing container 3 so as to be rotatable.

  Further, the developing container 3 is rotated in contact with the developing roller 1, and is supplied to the developing roller 1 with a supply roller 2 that supplies toner T to the developing roller 1 and one end abutting against the developing roller 1. A regulating blade (developer regulating member) 5 for regulating the toner T into a thin layer is disposed. As will be described later, the supply roller 2 also functions as a detection member that detects the amount of developer in the developer container 3.

  In this embodiment, a negatively chargeable non-magnetic one-component toner T is used as a developer, and during development, the toner T is negatively frictionally charged and the degree of aggregation of the toner is 15%. The toner aggregation degree was measured as follows.

  As a measuring apparatus, a powder tester (manufactured by Hosokawa Micron Corporation) having a digital vibrometer (manufactured by DEGITAL VIBRATION METERMODEL 1332 SHOWA SOKKI CORPORATION) was used.

  As a measurement method, set 390 mesh, 200 mesh, and 100 mesh sieves on a shaking table in the order of narrow opening, that is, 390 mesh, 200 mesh, and 100 mesh sieves so that 100 mesh sieve is at the top. did.

  Add 5 g of accurately weighed sample (toner) to the set 100 mesh sieve, adjust the displacement value of the digital vibrometer to 0.60 mm (peak-to-peak), and apply vibration for 15 seconds. It was. Thereafter, the mass of the sample remaining on each sieve was measured to obtain the degree of aggregation based on the following formula.

The measurement samples at that time were each left for 24 hours in an environment of 23 ° C. and 60% RH in advance, and the measurement was performed in an environment of 23 ° C. and 60% RH.
Aggregation degree (%) = (residual sample mass on 100 mesh sieve / 5 g) × 100 + (residual sample mass on 200 mesh sieve / 5 g) × 60 + (residual sample mass on 390 mesh sieve / 5 g) × 20

  In the developing device 4, the opening of the developing container 3 is provided below, and the weight of the toner T is applied to the developing roller 1 and the supply roller 2 installed in the opening. Such an arrangement is preferable for easily detecting the amount of toner in the developing container 3 because the toner easily enters the supply roller 2.

  The developing roller 1 is provided with a semiconductive elastic rubber layer 1b mixed with a conductive agent around the conductive support 1a, and is rotated in the direction A in the figure. Further, a cored bar electrode having an outer diameter of φ6 (mm) is used for the conductive support 1a, and a semiconductive silicon rubber layer 1b in which a conductive agent is blended is provided around the cored bar electrode.

Further, the surface layer of the silicon rubber layer 1b is coated with an acrylic / urethane rubber layer 1c of about 20 (μm), and the entire outer diameter of the developing roller 1 is φ12 (mm). The resistance of the developing roller 1 is 1 × 10 ⁶ (Ω).

  Here, a method for measuring the resistance of the developing roller 1 will be described.

  The developing roller 1 is brought into contact with an aluminum sleeve having a diameter of 30 mm with a contact load of 9.8 N. By rotating the aluminum sleeve, the developing roller 1 is driven to rotate relative to the aluminum sleeve at 60 rpm.

  Next, a DC voltage of −50 V is applied to the developing roller 1. At that time, a resistance of 10 kΩ is provided on the ground side, the current is calculated by measuring the voltage at both ends, and the resistance of the developing roller 1 is calculated.

If the volume resistance of the developing roller 1 is larger than 1 × 10 ⁹ (Ω), the developing bias voltage value on the surface of the developing roller 1 decreases, and the DC electric field in the developing area decreases, thereby reducing the developing efficiency. Therefore, there arises a problem that the image density is lowered. Therefore, in order to prevent such a problem, the resistance of the developing roller 1 is preferably set to 1 × 10 ⁹ (Ω) or less.

  The supply roller 2 as a developer supply member and as a developer amount detection member includes a conductive support and a foam layer supported by the conductive support. Specifically, a foamed urethane layer as a foamed layer composed of a cored bar electrode 2a having an outer diameter of φ5 (mm) as a conductive support, and an open cell (open cell) in which bubbles are connected to the periphery thereof. 2b is provided and rotates in the direction B in the figure.

The outer diameter of the entire supply roller 2 including the urethane foam layer 2b is φ13 (mm). By making the urethane of the surface layer into an open cell body, a large amount of toner can enter the supply roller 2, so that it is possible to improve the performance of toner amount detection described later. Further, the resistance of the supply roller 2 in the present embodiment is 1 × 10 ⁹ (Ω).

  Here, a method for measuring the resistance of the supply roller 2 will be described. The supply roller 2 is brought into contact with an aluminum sleeve having a diameter of 30 mm so that an intrusion amount described later is 1.5 mm. By rotating the aluminum sleeve, the supply roller 2 is driven to rotate relative to the aluminum sleeve at 30 rpm.

  Next, a DC voltage of −50 V is applied to the developing roller 1. At that time, a resistance of 10 kΩ is provided on the ground side, the current is calculated by measuring the voltage at both ends, and the resistance of the supply roller 2 is calculated. In the present embodiment, the surface cell diameter of the supply roller 2 is 50 μm to 1000 μm.

  Here, the cell diameter means the average diameter of the foamed cells having an arbitrary cross section. First, the area of the foamed cell that is the maximum is measured from the enlarged image of the arbitrary cross section, and the maximum cell diameter is converted from this area by converting the equivalent circle diameter. Get. And after deleting the foam cell which is 1/2 or less of this maximum cell diameter as noise, it points out the average value of each cell diameter converted similarly from the remaining individual cell area.

  The air flow rate on the surface of the supply roller 2 was 1.8 (liter / minute) or more. Here, the “surface ventilation” of the supply roller 2 in the present embodiment will be described in detail.

  In the present embodiment, the “aeration amount” is defined so that toner inside and outside the supply roller 2 is smoothly discharged and sucked, and the inside of the supply roller 2 and the outside of the supply roller 2 are in an equilibrium state. Since the toner mixed with air and turned into a powder fluid is discharged and sucked through the “surface layer surface” of the supply roller, it is important to directly define the “aeration amount passing through the surface layer surface”. FIG. 2 is a diagram showing a method for measuring the “surface ventilation”.

  First, the supply roller 2 of the present embodiment is inserted into a measurement jig 18 as shown in FIG. The measurement jig 18 shown in FIG. 3 has a through-hole of φ10 (mm) passed through the side surface of a hollow cylindrical body, and is made so that the central axis of the through-hole and the cylinder axis are orthogonal to each other.

The hollow cylinder has an inner diameter that is 1 mm smaller than the outer diameter of the supply roller to be measured. This is to eliminate a gap between the inner surface of the cylindrical body of the measuring jig 18 and the supply roller to be measured.
Since the supply roller 2 in the present embodiment has an outer diameter of φ13 (mm), the inner diameter of the measuring jig 18 is φ12 (mm).

  The measuring jig 18 into which the supply roller 2 is inserted is attached to a ventilation holder 19 as shown in FIG. The ventilation holder 19 has a T-shape in which a connection pipe 19b for attaching a ventilation pipe 21 leading to the decompression pump 20 is connected to the side surface of the hollow cylindrical body 19a, and a part corresponding to the opposite side of the connection part of the connection pipe 19b It has a large cut-out shape.

  The inner diameter of the connecting pipe 19b is set to be larger than the through hole of the measuring jig 18. In the present embodiment, the inner diameter of the connecting pipe 19b is φ12 (mm). The inner diameter of the hollow cylindrical body 19a of the ventilation holder 19 is substantially the same as the outer diameter of the measuring jig 18, so that the measuring jig 18 can be inserted into the hollow cylindrical body 19a. As shown in FIG. 2, one of the through holes of the measuring jig 18 is exposed at the cutout portion of the hollow cylindrical body 19a, and the other of the through holes is installed so as to face the inner diameter of the connecting pipe 19b.

  As shown in FIG. 2, acrylic pipes 22a and 22b having one end connected to the hollow cylindrical body 19a are installed on the left and right sides of the hollow cylindrical body 19a of the ventilation holder 19. The supply rollers 6 coming out from the left and right of the measuring jig 18 are accommodated in the acrylic pipes 22a and 22b.

  In the middle of the vent pipe 21, a flow meter 23 (KZ type air flow rate measuring device: Daiei Chemical Seiki Seisakusho) and a differential pressure adjusting valve 24 are installed.

  When the inside of the vent pipe 21 is evacuated by the decompression pump 20, the measurement jig 18, the vent holder 19, the vent pipe 21, acrylic, The connecting portions of the pipes 22a and 22b are sealed with tape or grease.

  The “surface aeration” is measured as follows.

  First, in FIG. 2, the pressure reducing pump 20 is operated without the supply roller 2 installed, and the measured value of the flow meter 23 is stably 10.8 (liters / minute) by the differential pressure adjusting valve 24. Adjust. Thereafter, the supply roller 2 to be measured is installed, carefully sealed as described above, and the measured value of the flow meter 23 is measured as “surface ventilation” under the same exhaust conditions as described above. As a matter of course, the “surface aeration amount” takes a value when the measured value of the flow meter 23 is sufficiently stabilized.

  The air flow passing through the supply roller 2 flows in from the surface of the urethane foam layer 2b located in the exposed through hole of the measurement jig 18, passes through the inside of the urethane foam layer 2b, and passes through the other side of the measurement jig 18. It flows out from the surface of the urethane foam layer 2b located in the through hole.

  The surface of the urethane foam layer 2b of the general supply roller 2 is often different from the inside of the urethane foam layer 2b. For example, when the supply roller 2 is formed by in-mold foaming, a skin layer having an opening ratio of cells on the surface different from the inside may appear on the surface.

  In addition, there is a type in which the surface of the urethane foam layer 2b is not formed as a simple cylindrical surface but is intentionally provided with irregularities. The toner powder fluid entering and exiting the inside and outside of the foamed urethane layer 2b may be affected by the above-described surface state, and its behavior cannot be captured only by measuring the bulk air flow rate as in JIS-L1096.

Therefore, in the present invention, the above-described air flow measurement method for measuring the air flow flowing in / out from the surface of the foamed urethane layer 2b is adopted, and the above-described equilibrium state (or a state close thereto) of the toner powder fluid is used. Was the main parameter for the appearance.

  The developing roller 1 is rotated in the direction A in FIG. 1 and the supply roller 2 is rotated in the direction B in the figure. The distance between the rotation centers is set to 11 (mm). The hardness of the urethane foam layer 2b is sufficiently softer than that of the silicon rubber layer 1b and the acrylic / urethane rubber layer 1c, so that the surface of the developing roller 1 is in a state where the foamed urethane layer 2b is crushed by a maximum of 1.5 (mm). In contact.

  The maximum crushing amount is the position of the surface of the foamed urethane layer 2b when the developing roller 1 is not in contact with the foamed urethane layer 2b, and when the developing roller 1 is in contact with the foamed urethane layer 2b during normal use. This is the maximum distance from the surface position of the urethane foam layer 2b. This maximum crushing amount is referred to as the amount of intrusion of the developing roller 1 with respect to the supply roller 2.

  The rotation speed of the developing roller 1 is 130 (rpm), and the rotation speed of the supply roller 2 is 100 (rpm). As the developing roller 1 and the supply roller 2 rotate, the urethane foam layer 2 b is crushed at the contact portion with the developing roller 1.

  At this time, the toner T held in or on the surface of the urethane foam layer 2 b of the supply roller 2 is discharged from the surface of the urethane foam layer 2 b, and a part of the toner T is transferred to the surface of the developing roller 1.

  The toner T transferred to the surface of the developing roller 1 is uniformly regulated on the developing roller 1 by a regulating blade 5 provided in contact with the contact portion downstream in the rotation direction of the developing roller 1.

  In the above process, the toner T is rubbed at the contact portion between the developing roller 1 and the supply roller 2 or the regulating portion between the developing roller 1 and the regulating blade 5, so that a desired triboelectric charge (negative charge in this example) is obtained. ). Further, as shown in FIG. 1, the developing residual toner on the developing roller 1 is peeled off and removed by the supply roller 2 by rotating in the opposite directions at the contact portion between the developing roller 1 and the supply roller 2.

  Next, the operation when the developing device according to the present embodiment is mounted on the image forming apparatus will be described with reference to FIG. FIG. 5 shows an attaching / detaching operation of the image forming apparatus according to the present embodiment and the developing device described above attached to and detached from the image forming apparatus.

  In FIG. 5A, the photosensitive drum 11 as an image carrier rotates in the direction of arrow E. When the image forming process is started, the photosensitive drum 11 is uniformly charged by a charging roller 12 as a charging device. Then, it exposes with the laser beam from the laser optical apparatus 13 which is an exposure means, and an electrostatic latent image is formed in the surface.

  The electrostatic latent image is developed by the developing device 4 described above and visualized as a toner image. In this embodiment, the toner adheres to the exposed portion of the photosensitive drum 11 and is reversely developed.

  The visualized toner image on the photosensitive drum 11 is transferred by a transfer roller 14 to a recording medium 15 as a transfer material. Untransferred toner remaining on the photosensitive drum 11 without being transferred is scraped off by a cleaning blade 17 as a cleaning member and stored in a waste toner container 18.

The cleaned photosensitive drum 11 repeats the above process to form an image on the recording medium 15. On the other hand, the recording medium 15 onto which the toner image has been transferred is permanently fixed by the fixing device 16 and then discharged outside the apparatus main body.

  In the present embodiment, the developing device 4 is provided as a cartridge 20 that is configured integrally with the photosensitive drum 11 and the charging roller 12, the cleaning blade 17, and the waste toner container 18. The cartridge 20 opens an opening / closing window at the top of the image forming apparatus in the direction G in the drawing, and the user pulls it in the direction H in FIG. On the other hand, it is removable.

  In this embodiment, a DC voltage of −1000 V is applied to the charging roller 12 to charge the surface of the photosensitive drum 11 to about −500 V. This potential is referred to as dark portion potential Vd. For a predetermined time until the potential Vd of the photosensitive drum 11 is stabilized, the developing device 4 is maintained in a state in which the photosensitive drum 11 and the developing roller 1 are separated from each other as shown in FIG. The separation cam 42 is configured to be rotatable by drive means and drive transmission means (not shown) provided in the image forming apparatus, and when separating the developing roller 1, as shown in FIG. In this state, a predetermined position (force receiving portion 43) on the rear surface of the developing device 4 is pushed.

  In addition, the developing device 4 includes a force receiving portion 43 that receives a force that allows the developing container 3 to move between a first position where the developing operation is performed by the developing roller 1 and a second position where the developing operation is not performed. Prepare. The force receiving portion 43 is provided at the predetermined position on the back surface of the developing device 4 of the cartridge 20. The force receiving portion 43 has performances such as a surface slipping performance required at the time of contact rotation with the separation cam 42 and a hardness that does not deform even in the separation state where the force is most applied.

  By the rotation operation of the separation cam 42, the cam surface of the separation cam 42 presses the force receiving portion 43 of the cartridge 20, and the developing device 4 rotates about the swing center 40 as a rotation axis, and the developing device 4 and the waste toner container 18. The reaction force of the push spring 41 provided between the two is overcome.

  The developing roller 1 is moved from the contact position (FIG. 5B) to the separated position (FIG. 5C) with respect to the photosensitive drum 11 by the swing of the developing device 4.

  The posture position of the developing device 4 in which the developing roller 1 is in contact with the photosensitive drum 11 is referred to as a first position (developing position), and the posture of the developing device in which the developing roller 1 is separated from the photosensitive drum 11. The position is referred to as a second position (non-development position). Of course, the developing operation is not performed in the second position.

  Waiting for the potential Vd of the photosensitive drum 11 to become stable, the photosensitive drum 11 is exposed by laser light from the laser optical device 13 serving as exposure means, and an electrostatic latent image is formed on the surface thereof. The surface potential of the exposed part is about −100V. This potential is called a bright portion potential Vl.

  Also, at a predetermined timing, the developing roller 1 and the supply roller 2 start to rotate by a driving unit and a driving transmission unit (not shown) provided in the image forming apparatus, and the subsequent electrostatic latent image developing process is performed. Prepare.

  The separation cam 42 is rotated by the driving means provided in the main body of the image forming apparatus so that the developing device 4 takes the separation position A as shown in FIG. In the separation position A, the force that was pushing the force receiving portion 43 on the rear surface of the developing device is released.

Therefore, due to the force of the pressing spring 41 provided between the developing device 4 and the waste toner container 18, the developing device 4 rotates about the swing center 40 as the rotation axis and the photosensitive drum 11 contacts the developing roller 1 (FIG. 5). (C)). At this time, a DC voltage of −300 V is applied to the developing roller 1 as a developing bias at a predetermined timing.

  The first position of the developing device is a position for developing the electrostatic latent image formed on the photosensitive drum 11 by contacting the developing roller 1 and the photosensitive drum 11 in this manner.

  After the electrostatic latent image is developed, the separation cam 42 rotates to the separation position B again. As a result, the force receiving portion 43 on the rear surface of the developing device is pushed, and the developing device 4 rotates around the swing center 40 as a rotation axis, and overcomes the reaction force of the pressing spring 41 provided between the developing device 4 and the waste toner container 18. Thus, the developing roller 1 is separated from the photosensitive drum 11. That is, the developing device 4 is moved again to the second position.

  At the same time, the rotation driving of the developing roller 1 and the supply roller 2 is stopped, and the application of the developing bias to the developing roller 1 is stopped.

  In the present embodiment, the electrostatic capacity between the developing roller 1 and the supply roller 2 can be detected at the second position (FIG. 5C) where the developing roller 1 is separated from the photosensitive drum 11. The remaining amount of toner in the developing device 4 is detected.

  A method for detecting the remaining amount of toner using the change in capacitance in the present embodiment will be described with reference to FIGS.

  FIG. 6 shows a state in which the developing device 4 of the present embodiment is installed in the image forming apparatus 10, and reference numeral 25 denotes a contact electrode attached to the developing device that is electrically connected to the core metal electrode 1 a of the developing roller 1. Further, a contact electrode 26 corresponding to the contact electrode 25 is provided on the main body side of the image forming apparatus 10, and the contact electrode 26 is connected to a capacitance detecting device 29 inside the main body of the image forming apparatus 10.

  Similarly, a contact electrode 27 attached to the developing device, which is electrically connected to the cored bar electrode 2a of the supply roller 2, and a corresponding contact electrode 28 on the main body side of the image forming apparatus 10 are provided. It is connected to the AC bias power source 30 for detection inside the main body of the apparatus 10.

  A state where the developing device 4 is installed at a predetermined position in the image forming apparatus 10, a first position where the developing roller 1 and the photosensitive drum 11 are in contact, and a second position where the developing roller 1 and the photosensitive drum 11 are separated from each other. In both positions, the contact electrodes 25 and 26 and the contact electrodes 27 and 28 are conductive.

  That is, even when the developing device 4 swings between the first position and the second position, the contact electrode 25 and the contact electrode 26, and the contact electrode 27 and the contact electrode 28 remain in contact with each other. During a normal developing operation, the developing device is in the first position, and a developing bias (DC voltage) is applied to the electrode 25 via the electrode 26.

  At this time, the same voltage as the developing bias is applied to the electrode 27 via the electrode 28. That is, during the developing operation, since the electrode 25 and the electrode 27 are at the same potential, an electric field is not formed between the developing roller and the supply roller. As described above, during the developing operation, the electrostatic capacitance detection device 29 and the AC bias power source 30 are switched to the developing bias power source.

  Next, as shown in FIG. 7, during the non-development operation, the developing device 4 is in the second position. In this embodiment, the remaining amount of toner is detected from the bias power source 30 to the conductive core 2 a of the supply roller 2. The remaining amount of toner in the developing device 4 is detected by applying a bias. As the toner remaining amount detection bias, an AC bias having a frequency of 50 KHz and Vpp = 200 V is used.

A voltage is induced on the conductive metal core 1 a of the developing roller 1 by a toner remaining amount detection bias, and this voltage is detected by a detector 29.

  The second position where the developing operation is not performed, that is, the state where the photosensitive drum 11 and the developing roller 1 are separated from each other is a non-developing operation. Specifically, in such a case, for example, between the sheets on which image formation is not performed, or when the image forming process is completed and the recording medium 15 is discharged from the image forming apparatus to the outside of the apparatus (so-called so-called) This can be realized in a post-rotation).

  At this time, since the photosensitive drum 11 and the developing roller 1 are separated from each other at the second position, even when an AC bias is applied as a toner remaining amount detection bias, a white background stain called fog is not generated. . Further, no unpleasant impact sound is generated when the developing roller and the photosensitive drum come into contact with each other and vibrate and vibrate.

  A configuration in which a separate antenna is provided in the developing chamber by applying an AC bias from the conductive core 2a of the supply roller 2 for the purpose of detecting the remaining amount of toner and using the developing roller 1 as an antenna for detecting capacitance. In this case, it is possible to prevent toner conveyance hindrance that occurs in

  FIG. 5B and FIG. 5C show the contact / separation operation of the photosensitive drum 11 and the developing roller 1, that is, the first position where the developing operation is performed and the second position where the developing operation is not performed. As described above, naturally, the posture of the developing device 4 changes, and the toner moves accordingly.

  At this time, in the developing device 4 of the present embodiment, an AC bias is applied from the conductive core 2a of the supply roller 2 to detect the remaining amount of toner, and the developing roller 1 is used as a capacitance detection antenna. By using it, the change in the electrostatic capacity of the toner contained in the supply roller 2 is measured.

  Therefore, the amount of toner contained in the supply roller 2 does not change depending on the attitude of the developing device 4 and the movement of the toner T accompanying the contact / separation operation, that is, the amount of toner existing between the development roller 1 and the antenna (supply roller). Does not change, so the voltage output induced in the antenna does not change.

  That is, since the supply roller 2 includes a foam layer through which the toner can enter, even if the attitude of the developing device changes, the toner in the foam layer hardly moves, and the voltage output does not change.

  In addition, in the developing device 4 having a non-magnetic one-component contact method according to the present embodiment, when the electrostatic capacity residual inspection is performed, that is, the developing roller 1 and the photosensitive drum 11 are separated from each other. , The driving of the developing roller 1 and the supply roller 2 is stopped.

  By stopping the driving of the developing roller 1 and the supply roller 2, the supply of toner to the developing roller 1 and the stripping of undeveloped toner are interrupted, and the amount of toner contained in the supply roller 2 is in the middle of detecting the remaining amount of toner. Thus, the remaining toner amount detection accuracy can be improved.

  FIG. 8 shows a flowchart of toner remaining amount detection according to the present embodiment. The toner remaining amount is detected when the developing device 4 moves from the first position to the second position after the image forming operation is completed, so that the photosensitive drum 11 and the developing roller 1 are separated from each other. The driving of the roller 1 and the supply roller 2 is stopped. Thereafter, a toner remaining amount detection is performed by applying a toner remaining amount detection bias.

  FIG. 9 shows the output value of the capacitance detection device 29 when the toner T is filled in the developing device 4 of the present embodiment and gradually consumed, with a triangle point and a solid line. In the present embodiment, the surface ventilation amount L of the supply roller is 3.0 (liters / minute). The measurement environment is 23 ° C. and 60% Rh.

  As shown in FIG. 9, in the configuration of the developing device 4 of the present embodiment, the remaining amount of toner T in the developing device 4 and the output value of the capacitance detecting device 29 may be relatively linear. It changes with correlation.

  In the display of the toner amount, a reference value is provided, and the output value of the capacitance detecting device 29 is compared with the reference value, and it is determined that there is no toner when the value is below the reference value. If it is determined that there is no toner, a warning such as “no toner” is displayed on the main body of the image forming apparatus or a computer connected to the image forming apparatus, or the image forming operation of the image forming apparatus is stopped. Also good.

  Further, when the process cartridge 20 that can be attached to and detached from the main body of the image forming apparatus is used, the main body of the image forming apparatus may be notified of the replacement time of the cartridge.

  Further, as shown in FIG. 9, since the toner amount and the output value of the capacitance detecting device 29 are correlated, the desired toner remaining amount of the toner T in the developing device 4 is such as “low toner amount”. Warning display can be performed. Furthermore, a plurality of warnings can be displayed by providing a plurality of reference values.

  For example, assuming that the amount of new toner stored in the developing container 3 is 100%, the current remaining amount of toner in use may be displayed stepwise in%.

  For example, by changing the foaming rate of the foam layer of the supply roller 2, several supply rollers having different surface ventilation amounts according to the present embodiment are created. Then, this was incorporated into a developing device having the same configuration as that of the present embodiment, and compared with the output result of the present embodiment (the surface air flow rate of the supply roller is 3.0 (liters / minute)).

  Therefore, as another aspect of the present embodiment, an output value when measured under the same conditions in a developing device using a supply roller having a foamed urethane layer having a surface air permeability of 1.8 (liters / minute) is shown in FIG. 8 is shown by a square point and a broken line.

  Further, as Comparative Example 1, the output value when measured under the same conditions with a developing device using a supply roller having a foamed urethane layer having a surface air permeability of 1.5 (liter / min) is shown in FIG. Indicated by dots and broken lines.

  Furthermore, as Comparative Example 2, the output value when measured under the same conditions with a developing device using a supply roller having a foamed urethane layer with a surface air permeability of 0.8 (liters / minute) is shown in FIG. And indicated by a thin solid line.

  As described above, when this embodiment (including other aspects) is compared with Comparative Examples 1 and 2, the output values of Comparative Examples 1 and 2 hardly change until the toner T is consumed more than half from the beginning of use. It turned out that the output change appeared after quite a little.

  FIG. 10 shows a plot of the remaining amount of toner T in the developing device 4 and the amount of toner contained in the supply roller 2 at that time in the first embodiment.

  In FIG. 10, the toner T is consumed under the same conditions as in FIG. 9, and after measuring the electrostatic capacity with different remaining amounts of toner, the supply roller 2 is taken out and the amount of toner T contained therein is measured (use) The difference from the weight of the previous supply roller 2 was taken). As shown in FIG. 10, it can be seen that the remaining amount of toner in the developing device and the amount of toner contained in the supply roller are relatively linear and change while maintaining a good correlation.

  In addition, when the air flow rate of the supply roller disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 11-288161) was measured by the measurement method in the present embodiment, it was 0.3 to 1.3 (liters / minute). .

  In the above measurement, the electrostatic capacity output value of the developing device 4 of the present embodiment and the amount of toner contained in the supply roller 2 at that time are plotted in FIG. As shown in FIG. 11, the remaining amount of toner in the developing device and the amount of toner contained in the supply roller are almost linear and maintain a very good correlation. This indicates that the configuration of the present embodiment accurately measures the capacitance change in the supply roller 2.

  In addition, several supply rollers having different surface airflow rates were prepared, and the output results were compared using a developing device having the same configuration as the present embodiment. The result is shown in FIG.

  In the above description, the surface airflow rate is set to 3.0 (liter / minute) or 1.8 (liter / minute), but the surface airflow amount in the present embodiment is 3.9 (liter / minute) or 5. It may be 0 (liters / minute).

  Output values when measured under the same conditions with a developing device using a supply roller having a urethane foam layer with a surface air flow rate of 3.9 (liters / minute) are shown by squares and broken lines in FIG.

  In addition, the output value when measured under the same conditions with a developing device using a supply roller having a foamed urethane layer with a surface air flow rate of 5.0 (liter / min) is shown by a dot and a broken line in FIG. It was.

  As shown in FIG. 12, the absolute absolute value of the capacitance detection output value increases as the air flow rate increases. However, the amount of change corresponding to the toner amount in the developing device is 3-5 (liters / minute). The same applies to the supply roller 2).

  In other words, if the supply roller has an air flow rate of 1.8 (liters / minute) or more, the correlation between the detected electrostatic capacity output value and the toner amount in the developing container is good, and the detection accuracy of the remaining toner amount is improved. To do. In addition, if the air flow rate is large, the pores of the foam layer of the supply roller are increased, the strength of the supply roller is reduced, and the foam layer of the supply roller is easily torn. In order to prevent this, the air flow rate is 5 It is preferably (L / min) or less.

  By appropriately setting the air flow rate of the supply roller as described above, the amount of toner contained in the supply roller is increased, and the amount of toner contained in the supply roller is equal to the amount of toner contained in the developing container. It decreases according to the decrease (see FIG. 10).

  In addition, the output value of the capacitance between the developing roller and the supply roller decreases as the amount of toner in the supply roller decreases (see FIG. 11).

  Therefore, in order to determine the amount of toner contained in the developing container, it is effective to measure the output value of the electrostatic capacity between the developing roller and the supply roller (see FIG. 12).

  In order to increase the amount of toner contained in the supply roller, the average cell diameter on the surface of the foam layer of the supply roller is preferably larger than the average particle diameter (for example, weight average particle diameter) of the toner.

  The toner in the supply roller starts to deform when the supply roller starts to contact the developing roller, and is partially discharged. When the supply roller finishes contacting the developing roller, the deformation of the supply roller returns to the original state. Some have been sucked.

  As described above, although the toner enters and leaves the supply roller, the toner amount in the supply roller is generally kept in an equilibrium state unless the toner amount in the developing container is changed. In order to accurately measure the output value of the capacitance when more accurately determining the amount of toner in the supply roller, it is preferable that toner does not enter and exit the supply roller as described above. It is better to stop the rotation of the supply roller and measure.

  The correlation between the remaining amount of toner in the developing device and the amount of toner contained in the supply roller shown in FIG. 10 depends on the degree of aggregation of the toner T. It is considered that the lower the cohesion degree, the easier the toner enters and leaves the supply roller, and thus the better the correlation between the remaining amount of toner in the developing device and the amount of toner contained in the supply roller.

  In the image forming apparatus 10 according to the present embodiment, an image forming operation is performed, and the degree of aggregation of the toner T remaining in the developing container in a state where the toner T in the developing apparatus is sufficiently consumed is measured, and is 30%. there were. In general, the higher the usage of the toner T in the developing container, the higher the aggregation degree of the toner T. Therefore, the aggregation degree of the toner T in the developing device before the image forming operation is lower than 30%. Can be guessed.

  In other words, a toner having a degree of aggregation of 30% or less can be used without any problem in creating a situation where the toner enters and leaves the supply roller, which is a feature of the present invention.

  The amount of toner contained in the supply roller has a correlation with the amount of toner in the toner container. Therefore, as the weight of the toner in the toner container is directly applied to the supply roller, the correlation between the remaining amount of toner in the developing device and the amount of toner contained in the supply roller becomes higher as shown in FIG. For this reason, as in the present embodiment, it is possible to improve the accuracy of the residual toner detection detection by arranging the supply roller at the opening in the toner container.

  In the image forming apparatus 10 according to the above-described embodiment, a detector that applies a toner remaining amount detection bias to the supply roller 2 and detects a voltage induced in the developing roller 1 is disposed. However, the same effect can be obtained even in a configuration in which a detector for detecting a voltage induced in the supply roller 2 by applying a toner remaining amount detection bias to the developing roller 1 is arranged.

  In the present embodiment, a DC bias is applied to the developing roller 1 and the supply roller 2 during image formation. This is because, when an AC voltage is applied to the cored bar electrode 2a of the supply roller 2 during image formation, the balance between the supply of toner by the supply roller 2 and the removal of the development residual toner is lost.

  As a result, there is a concern that the image stability may be hindered. Therefore, the remaining toner amount detecting device (developer amount measuring device) is operated at times other than image formation. For example, the rotation can be performed before or after image formation.

  In the present embodiment, the toner remaining amount detection device is configured to operate during post-rotation. In the case where the toner remaining amount detecting device is operated at a timing other than during image formation, in order to detect the remaining amount of toner when continuous printing is performed, it is necessary to make a timing for measuring the remaining amount of toner for each print.

  However, this reduces the printing productivity. In order to avoid this, if the remaining amount of toner is not detected during continuous printing, there is a possibility of printing without noticing the absence of toner in the developing container.

Therefore, the present embodiment is characterized in that image dot counting means for forming an image on the photosensitive drum 11 is provided. In the present embodiment, this image dot counting means is realized by the CPU 53 and counts the number of image dots formed on the photosensitive drum 11.

That is, in the present embodiment, as a means for detecting the remaining amount of toner in the developing container, a high-accuracy toner remaining amount detection device and the number of image dots that are less accurate than the remaining toner amount detection device are used. Then, the number of image dots formed on the photosensitive drum 11 by the laser light from the laser optical device 13 is counted.

  In this embodiment, the toner used for printing is estimated by converting the number of image dots into the toner weight. For this purpose, it is necessary to know in advance the amount of toner used per dot. In addition, the coefficient of a [gram / dot] is stored in the image forming apparatus. This a [gram / dot] can be changed according to the use environment (temperature / humidity).

  Therefore, in the present embodiment, the number of image dots formed by the laser from the laser optical device 13 on the image carrier is counted, a predetermined calculation is performed on the number of image dots, and the toner weight used is converted. .

  Then, the used toner weight is subtracted from the toner weight measured by the toner remaining amount detection device before the start of printing. When this value falls below a predetermined value, continuous printing is stopped and measurement is performed by the toner remaining amount detection device. .

  As described above, the number of image dots is used as an auxiliary to accurately indicate the absence of toner in the developing container. However, the accuracy of the residual detection system based on the number of image dots may be reduced depending on the environment and the type of image. Therefore, the residual detection system based on the number of image dots is only used as an auxiliary.

  Hereinafter, the operation of the remaining toner amount detection system using the number of image dots of the present invention will be described in detail with reference to the flowchart of FIG. FIG. 14 is a flowchart of the operation of the image forming apparatus shown in FIG.

  The image forming apparatus is configured such that the number d of image dots can be stored in an image dot storage unit (CPU). Information on the number of image dots is updated and stored for each print. Also, the number of image dots is obtained and stored by the CPU 53 by counting the lighting time of the laser light source from the laser optical device 13 and dividing it by the lighting time of one dot.

  In the flowchart of FIG. 14, a print signal is input from the host 51 (S1). At this time, the remaining toner amount W = w1, which is the detection result of the previous remaining toner amount detection, is already stored in the image forming apparatus.

  Thereafter, the image forming apparatus 10 starts an image forming operation, and rotates the developing roller 1 and forms an electrostatic latent image on the photosensitive drum 11 at an appropriate timing (S2).

  At this time, the image dot d is counted (S3). At this time, as shown in FIG. 3, dots are added during continuous printing, and the total number of dots in the continuous printing is always expressed (S3).

  Next, it is confirmed whether there is a continuous print request (S4).

If there is no continuous print request, post-rotation is performed after image formation is completed, the remaining amount of toner is detected during non-image formation, and the toner amount W is updated to the measurement result w2 (S5). A comparison is made with a threshold value Ew for determining the absence of toner (S6).

  If W is greater than E, the printing is terminated and a transition is made to a standby state (S7). If W is equal to or less than E, the user is warned that there is no toner in the developing container (S8).

  If there is a continuous print request, the toner amount Wd consumed by multiplying the image dot d by a coefficient of a [gram / dot] is calculated (S9).

  Next, the consumed toner amount Wd is subtracted from the remaining toner amount W = w1 before printing, and W-Wd is compared with the threshold Ew for the absence of toner in the developing container. If W-Wd is larger than Ew, the number of continuous images is measured (S11), and the operation proceeds to image forming operation continuously (S3). At this time, d (m) measured in the next print is added to d up to the previous time.

  Of course, the threshold value E can also be set before a problem such as the toner falling from the developing device or an image defect occurs when the remaining amount of toner is low. If W−Wd is equal to or less than E, image formation is forcibly interrupted, post-rotation is performed, and the remaining toner amount is detected (S12). Further, the developer amount W is updated to the measurement result w3 obtained by the measurement operation of the toner remaining amount detection.

  Thereafter, the measurement result W = w3 based on the toner remaining amount detection is compared with the threshold value Ew for determining the absence of toner in the developing container (S13).

  When W is larger than Ew (S13), the image dot number d is returned to 0 (S14), and the printing operation is resumed (S2).

  If W is equal to or less than Ew, the user is warned that there is no toner in the developing container (S8). With such a configuration, it is possible to accurately detect the absence of toner in the developing container.

  In this embodiment, contact development is employed. However, the present invention is not limited to contact development, and is also effective in an image forming apparatus using a non-magnetic jumping development system using a toner supply roller.

  The present invention is also effective for an image forming apparatus in which a plurality of process cartridges having the same form as the present embodiment are arranged to obtain a full color image.

[Second Embodiment]
An image forming apparatus according to a second embodiment of the present invention will be described with reference to FIG. In the following description, the description of the same parts as those of the first embodiment is omitted.

  In the image forming apparatus according to the present embodiment, as a means for measuring the amount of developer in the developing container, a high-accuracy toner remaining amount detecting device and the number of image dots that are less accurate than the toner remaining amount detecting device are used.

Therefore, in the present embodiment, the number of image dots formed on the photosensitive drum 11 by the laser light from the laser optical device 13 is counted. In addition, the toner amount detected by the toner remaining amount detecting device before the start of printing is calculated to a predetermined value and converted into dots, whereby the amount of toner in the developing container that can be printed is handled as the number of usable dots. .

  By using this number of dots, it is possible to count even in the case of low printing. For example, when 1 gram = 1000 dots, there is an advantage that dot notation is easier to convert. Then, the number of image dots is subtracted from the number of remaining dots in the developing container, and when this value falls below a predetermined value, continuous printing is stopped and detection by the toner remaining amount detection device is performed.

  Since the voltage measured in detecting the remaining amount of toner and the amount of toner T in the developing container are substantially linear, it is possible to measure the remaining amount of toner T with the toner remaining amount detecting device. .

  Thus, the number of image dots is used as an auxiliary to accurately indicate the absence of toner in the developing container.

  Hereinafter, the operation of the remaining toner amount detection system using the number of image dots of the present invention will be described in detail with reference to the flowchart of FIG.

  The image forming apparatus can store the number d1 of printed image dots. Information on the number of image dots is updated and stored for each print. The number of image dots is calculated and stored by the CPU 53 by counting the lighting time of the laser light source of the laser optical device 13 and dividing it by the lighting time of one dot.

  In this embodiment, in order to grasp the number of printable dots, the usable toner weight in the container before the start of printing is converted into the number of image dots. For this purpose, it is necessary to know in advance the number of dots when 1 gram of toner is used. Therefore, the coefficient of b [dot / gram] is stored in the image forming apparatus.

  Further, the value of b [dot / gram] can be changed in accordance with each design.

  In the flowchart of FIG. 15, a print signal is input from the host 51 (S1).

  At this time, the developer remaining amount W = w1, which is the detection result of the previous toner remaining amount detection, is already stored. At this time, the toner amount W is multiplied by a coefficient of b [dot / gram], and converted to the number d2 of image dots corresponding to the usable toner weight in the developing container (S2).

  Then, the image forming apparatus main body 10 starts an image forming operation, rotates the developing roller 25 at an appropriate timing, forms an electrostatic latent image on the photosensitive drum 11, and starts a printing operation (S3).

  Thereafter, the number of image dots d is counted (S4), and it is confirmed whether there is a continuous print request (S5).

  If there is no continuous print request, post-rotation is performed after image formation is completed, the remaining toner amount is detected, the toner amount W is updated to the measurement result w2 (S6), and the toner amount W and the toner in the developing container are updated. A comparison is made with a threshold Ew for determining the absence (S7).

  If W is greater than Ew, the printing is terminated and a transition is made to the standby state (S9). If W is equal to or less than Ew, the user is warned that there is no toner in the developing container (S8). If there is a continuous print request, d2-d1 is compared with a threshold Ed for determining the absence of toner in the developing container (S10).

  When d2-d1 is larger than Ed, the second image dot number corresponding to the developer remaining amount is updated to d2-d1 (S11), and the process proceeds to the image forming operation continuously (S4).

  If d2-d1 is equal to or less than Ed, image formation is forcibly interrupted, post-rotation is performed, and the remaining toner amount is detected (S12). Further, the toner amount W is updated to the result w3 of the toner remaining amount detection.

  Thereafter, the measurement result W = w3 based on the toner remaining amount detection is compared with the threshold value Ew for determining the absence of toner in the developing container (S13).

  If W is larger than Ew, the second image dot number corresponding to the remaining amount of toner in the developing container is calculated again (S2), and the printing operation is resumed (S3).

  If W is equal to or less than Ew, the user is warned that there is no toner in the developing container (S8). With such a configuration, it is possible to accurately detect the absence of toner in the developing container.

  In this embodiment, as in the first embodiment, contact development is adopted. However, the present invention is not limited to contact development, and a non-magnetic jumping development system using a supply roller 2 is used. This is also effective in the image forming apparatus.

  The present invention is also effective for an image forming apparatus in which a plurality of process cartridges having the same form as the present embodiment are arranged to obtain a full color image.

[Third embodiment]
An image forming apparatus according to the third embodiment of the present invention will be described with reference to FIG. In the following description, the description of the same parts as those of the first embodiment is omitted.

  In the present embodiment, as a means for measuring the amount of developer in the developing container, a high-accuracy toner remaining amount detection device and the number of prints with less accuracy than the toner remaining amount detection device are used. Therefore, in the present embodiment, the number of printed sheets by the image forming apparatus 10 is counted.

  Further, the toner amount detected by the toner remaining amount detecting device before the start of printing is converted into a predetermined number of prints and converted into a printable number of sheets, and is handled as the minimum number of printable sheets. For this purpose, it is necessary to know in advance the amount of toner used when 100% printing is performed.

In addition, the count of c [gram / number of sheets] is stored in the image forming apparatus. However, this time, the amount of toner used when 100% printing is performed is stored. It is also possible to calculate the percentage from the user's specification history.

  The operation of the toner remaining amount detection system in the present embodiment will be described in detail with reference to the flowchart of FIG. FIG. 16 is an operation flowchart of the image forming apparatus shown in FIG.

  The image forming apparatus can store the print number p1 by the print number storage unit. The information on the number of prints is updated and stored for each print.

In the flowchart of FIG. 16, a print signal is input from the host 51 (S1).
. At this time, W = w1, which is the detection result of the previous toner remaining amount detection, is already stored in the image forming apparatus. At this time, the toner amount W is multiplied by a coefficient of 1 / c [number of sheets / gram] and converted to the minimum printable number P in the developing container (S2).

  Thereafter, the image forming apparatus body 10 starts an image forming operation, rotates the developing roller 1 at an appropriate timing, forms an electrostatic latent image on the photosensitive drum 11, and starts a printing operation (S3).

  At this time, as shown in FIG. 16, during the continuous printing, the number of prints is added to always represent the total number of prints in the continuous print (S4). Next, it is confirmed whether there is a continuous print request (S5).

  If there is no continuous print request, post-rotation is performed after the image formation is completed, the toner remaining amount is detected, the toner amount W is updated to the measurement result w2 (S6), and the toner amount W and no toner in the developing container are determined. Comparison is made with the threshold value Ew to be judged (S7).

  If W is greater than Ew, the printing is terminated and a transition is made to the standby state (S8). If W is equal to or less than Ew, the user is warned that there is no toner in the developing container (S9). If there is a continuous print request, it is checked whether the number of prints has reached the minimum printable number P = p1 (S10).

  If P ≠ p1, the number of prints is added (S11), and the process proceeds to the image forming operation (S4).

  If P = p1, the image formation is forcibly interrupted, post-rotation is performed, and the toner remaining amount is detected (S12). Further, the toner amount W is updated to the result w3 of the toner remaining amount detection.

  Thereafter, the measurement result W = w3 based on the toner remaining amount detection is compared with the threshold value Ew for determining the absence of toner in the developing container (S13).

  When W is larger than Ew (S14), the print number p1 is returned to the initial value 0 (S14), the printable number corresponding to the remaining amount of toner in the developing container is calculated again (S2), and the printing operation is restarted (S2). S3).

  If W is equal to or less than Ew, the user is warned that there is no toner in the developing container (S9). With such a configuration, it is possible to accurately detect the absence of toner in the developing container. Although the contact development is adopted in the present embodiment, the present invention is not limited to the contact development, and is also effective in an image forming apparatus using a non-magnetic jumping development system using a toner supply roller.

  The present invention is also effective for an image forming apparatus in which a plurality of process cartridges having the same form as the present embodiment are arranged to obtain a full color image.

1 is a schematic configuration diagram of a developing device according to a first embodiment of the present invention. It is a figure which shows the measuring method of "surface ventilation | gas_flowing amount". It is a figure which shows schematic structure of the jig used for ventilation | gas_flow amount measurement. It is a figure which shows the ventilation holder used for ventilation volume measurement. 1 is a schematic cross-sectional view of an image forming apparatus according to a first embodiment of the present invention. It is a figure which shows the mounting state of the developing device in the 1st Embodiment of this invention. 1 is a schematic configuration diagram of a toner remaining amount detection device according to a first embodiment of the present invention. 3 is a flowchart of toner remaining amount detection in the first embodiment of the present invention. 6 is a graph showing the relationship between the toner amount in the developing device and the output of the electrostatic capacity detector in the first embodiment of the present invention. It is a figure which shows the relationship between the toner amount in the image development apparatus in 1st Embodiment of this invention, and the toner amount contained in a supply roller. It is a graph which shows the relationship between the toner amount contained in a supply roller, and the output of a capacitance detector. 6 is a graph showing the relationship between the amount of toner in a developing device and the output of a capacitance detector. 1 is a schematic cross-sectional view of an image forming apparatus including a developing device to which the present invention is applied. 3 is a flowchart of toner remaining amount detection in the first embodiment of the present invention. 10 is a flowchart of toner remaining amount detection in the second embodiment of the present invention. 14 is a flowchart of toner remaining amount detection according to a third embodiment of the present invention. It is a schematic block diagram which shows the conventional developing device. It is a schematic block diagram which shows the conventional developing device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing roller 1a Conductive core metal of developing roller 2 Supply roller 2a Conductive core metal of supply roller 3 Toner container 4 Developing device 5 Control member 10 Image forming apparatus 11 Photosensitive drum 12 Charging roller 17 Cleaning blade 18 Waste toner container 29 Detector 30 Toner remaining amount detection bias power supply 40 Swing center 41 Push spring 42 Separating cam 43 Force receiving portion 51 Host 52 Controller 53 CPU
54 ROM

Claims (5)

A developer container having an opening and containing a developer;
A developer carrying body comprising a first conductive support and carrying a developer at the opening;
A second conductive support provided inside the developer container in contact with the developer carrier, and a foamed layer provided around the second conductive support; A rotatable developer supply member for supplying the developer to the agent carrier;
An image dot counting means for counting the number of image dots formed on the image carrier;
Have
A developer amount measuring device for measuring the developer amount in the developing container by detecting a capacitance between the first conductive support and the second conductive support during non-image formation. In an image forming apparatus comprising:
Control means for interrupting image formation during continuous printing and causing the developer amount measuring device to perform a measuring operation based on a result of comparing the value of the number of image dots and the measured value by the developer amount measuring device. An image forming apparatus. A developer container having an opening and containing a developer;
A developer carrying body comprising a first conductive support and carrying a developer at the opening;
A second conductive support provided inside the developer container in contact with the developer carrier, and a foamed layer provided around the second conductive support; A rotatable developer supply member for supplying the developer to the agent carrier;
Print number storage means for storing the number of printed sheets by the image forming apparatus;
Have
A developer amount measuring device for measuring the developer amount in the developing container by detecting a capacitance between the first conductive support and the second conductive support during non-image formation. In an image forming apparatus comprising:
Control means for interrupting image formation during continuous printing and causing the developer amount measuring device to perform a measuring operation based on a result of comparing the value of the printed sheet storage means and the measured value by the developer amount measuring device. An image forming apparatus. The image forming apparatus according to claim 1, further comprising an image dot storage unit that stores the number of image dots measured by the image dot counting unit. Said developer amount measuring device image forming apparatus according to claim 1 or 2, characterized in that the measuring operation in a state in which said image bearing member and said developer carrying member is separated. The image forming apparatus according to claim 1 or 2, characterized in that it comprises a developer amount storing means for storing the measurement results of the developer amount measuring device.

Images