JP2006113220A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus whose accuracy in the detection of a developer amount in a developer storage part is improved. <P>SOLUTION: The image forming apparatus A includes; the developer storage parts 4 and 5A; a developer carrier 5a for transporting the developer to a latent image on an image carrier 1; detecting members 31 and 32 for detecting the developer amount in the developer storage part, a developer amount detecting means 23 for generating a detection value corresponding to the developer amount in the developer storage part based on signals from the detecting members 31 and 32, and a control means 25 for switching the level of the developer amount as the detection result of the developer amount in the developer storage part based on the detection value from the developer amount detecting means, and the developer amount level is switched by the control means 25 in the case the detection values from the developer amount detecting means are the same. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention generally relates to an image forming apparatus using an electrostatic recording method, an electrophotographic method, or the like, which forms an image by developing an electrostatic image formed on an image carrier using a developer. More specifically, the present invention relates to an image forming apparatus provided with a developer amount detecting device that sequentially detects the amount of developer in the developer accommodating portion.

  Here, examples of the electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (for example, an LED printer, a laser beam printer, etc.), an electrophotographic facsimile apparatus, and an electrophotographic word processor. The cartridge that can be attached to and detached from the main body of the image forming apparatus includes a process cartridge, a developing device formed into a cartridge, or a developer containing portion formed into a cartridge. The process cartridge includes at least one of an electrophotographic photosensitive member, a charging unit that charges the electrophotographic photosensitive member, a developing unit that supplies a developer to the electrophotographic photosensitive member, and a cleaning unit that cleans the electrophotographic photosensitive member. The cartridge is integrally formed so that the cartridge can be attached to and detached from the main body of the electrophotographic image forming apparatus. In the present invention, the process cartridge has at least a developer container.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as an electrophotographic copying machine or a laser beam printer, light corresponding to image information is irradiated onto an electrophotographic photosensitive member (hereinafter simply referred to as “photosensitive member”), and the photosensitive member. A latent image is formed on top. This latent image is visualized as a toner image when a developer is supplied by the developing means. Further, the toner image on the photoconductor is transferred from the photoconductor to the recording medium, whereby an image is formed on the recording medium.

  In general, a developer container is connected to the developing means. Usually, a developing chamber as a housing of the developing means and a developer storage container connected thereto constitute a developer storage portion. Then, the developer in the developer accommodating portion is consumed by forming an image.

  In such an image forming apparatus, for the purpose of exchanging consumables such as a photoconductor and a developer and simplifying maintenance, the photoconductor and a developing unit, a charging unit, and a cleaning unit as a process unit acting on the photoconductor Further, there is a process cartridge system in which a developer storage container, a waste developer container, and the like are integrated as a process cartridge and can be attached to and detached from the image forming apparatus main body. According to this process cartridge system, the maintenance of the apparatus can be performed by the user himself / herself without depending on the service person, so that the operability can be remarkably improved. Therefore, this process cartridge system is widely used in electrophotographic image forming apparatuses.

  Further, the developing device including the developing means and the developer storage container may be a cartridge (developing cartridge) that can be attached to and detached from the image forming apparatus main body. Further, the developer container may be a cartridge (toner cartridge) that is detachable from the main body of the image forming apparatus alone.

  In the above-described cartridge type image forming apparatus, the user usually replaces the cartridge when the developer runs out. Thereby, an image can be formed again. Therefore, the image forming apparatus may be provided with means for detecting when the developer is consumed and notifying the user, that is, a developer amount detecting device.

  The developer amount detection device is provided with a detection means for detecting the developer amount level in the developer accommodating portion so that it can be known at any time how much developer that can be used for image formation remains in the cartridge. Provided in the image forming apparatus main body.

  In particular, there is provided an image forming apparatus that further improves convenience by not only detecting and notifying the user that the developer has been exhausted, but also detecting the amount of developer sequentially and notifying the user. is there. In such an image forming apparatus, for example, what percentage of the developer remaining when not used is calculated and sequentially notified to the user. Furthermore, a “no developer” display is displayed to notify that the amount of developer has decreased so that image formation of a predetermined quality cannot be performed, and a warning is given to the user that the remaining developer is low before image failure occurs. There is something to do.

  There is a capacitance detection method as one method of detection means that enables sequential detection of the developer amount level as described above. More specifically, there is the following plate antenna method as one method of the capacitance detection method. Conventionally, the developing means has a developer carrying member that carries the developer and conveys it to a portion (development region) facing the photoreceptor, and an AC voltage (usually a DC voltage is applied to the developer carrying member). There is a developing method for developing the latent image formed on the photosensitive member by applying the superposed. In a cartridge employing such a development system, a sheet metal as an electrode member is provided at a location facing the developer carrier or at a plurality of other locations. The electrostatic capacity between the sheet metal and the developer carrier (or between the sheet metal and the sheet metal) changes according to the amount of developer (insulating developer or the like) in the developer accommodating portion. Utilizing this, the developer amount level is detected sequentially.

  That is, if the space between the sheet metal and the developer carrier or between the sheet metal and the sheet metal is filled with the developer, the capacitance between them increases, and the space between the two increases as the developer decreases. The rate occupied by air increases and the capacitance decreases. Accordingly, if the relationship between the electrostatic capacity between the sheet metal and the developer carrier or the electrostatic capacity between the sheet metal and the sheet metal and the developer amount is obtained in advance, the electrostatic capacity is measured. Can detect the developer level.

  The capacitance is measured by measuring a current flowing through a sheet metal provided facing the developer carrier when an AC voltage is applied to the developer carrier. Alternatively, when a plurality of sheet metals are provided as a plurality of electrode members, when an AC voltage is applied to a predetermined sheet metal, the capacitance between the sheet metals is similarly measured by measuring the current flowing through the other sheet metal. can do. In this plate antenna type developer amount detecting device, in many cases, the developer amount is detected during image formation in which a developing bias is applied to the developer carrying member. The power source for developing bias and the power source for detecting the developer amount may be shared.

  Hereinafter, the plate antenna method will be further described by taking as an example the case of using a developer carrier and a sheet metal provided opposite to the developer carrier as electrode members in the capacitance detection method. The same applies to the case where the developer amount level is sequentially detected by measuring the capacitance between the sheet metals.

  In the above-described plate antenna system, generally, when a voltage is applied to the developer carrier, the current flowing through the sheet metal according to the electrostatic capacity between the developer carrier and the sheet metal, that is, the sheet metal depends on the amount of developer. The output signal is detected as a voltage value (hereinafter simply referred to as “detected voltage value”) by the developer amount detection means (detection circuit). Therefore, in practice, the electrostatic capacity corresponding to the developer amount is converted as a voltage value (detection voltage value). Then, the developer amount in the developer accommodating portion is derived from the relationship between the change amount of the detected voltage value and the developer amount, which are obtained in advance. In short, only when the change in the detection voltage value is recognized, an update for reducing the remaining amount display of the developer amount can be performed.

  A method for determining the developer amount from the association between the developer amount and the change amount of the detected voltage value is proposed in Patent Document 1.

  By the way, in recent years, an image forming apparatus in which a plurality of types of cartridges having different amounts of developer stored in a developer storage unit when not in use can be attached and detached has appeared. That is, in addition to a large-capacity cartridge that suppresses the running cost with a large amount of developer filled when the cartridge is not used, a small-capacity cartridge that suppresses the initial cost with a small amount of developer filled when the cartridge is not used can be used. Two or more types of cartridges can be used in the same apparatus.

  Further, in such an image forming apparatus in which a plurality of types of cartridges can be mounted, for example, when different types of cartridges are used alternately, it is difficult for the user himself to predict the life of the cartridges. Therefore, it is strongly desired to detect the developer amount sequentially from the viewpoint of usability.

  Therefore, when a plurality of types of cartridges such as a large-capacity cartridge and a small-capacity cartridge can be used in the same image forming apparatus, it is desirable to maintain high detection accuracy for sequential detection of the developer amount for any cartridge. It is.

  Here, for example, when the remaining developer amount is detected from 25% (1/4 of the total amount) to 0% in increments of 1% with a large-capacity cartridge, of course, a small-capacity cartridge that can be used in the same image forming apparatus Similarly, there are many needs to detect from the remaining developer amount of 25% (1/4 of the total amount) to 0% in increments of 1%. However, it was found that small-capacity cartridges are more difficult to detect than large-capacity cartridges.

  For example, if the large-capacity cartridge is a 20K cartridge (for example, a developer amount equivalent to 20000 A4 size 4% print), the amount of developer in the developer container is 1050 g, and the image is blank (development to a part of the image during development). If the amount of developer remaining in the developer container at the time of occurrence) is 50 g, the amount of developer that can be used is substantially 1000 g. 25% of this 1000 g is 250 g. Further, 1% of the developer amount of 1000 g is 10 g. Accordingly, in order to sequentially detect the developer amount in increments of 1% from the remaining developer amount of 25%, the change amount of the detected voltage value and the developer with respect to the change in the developer amount of 10 g from the developer amount of 250 g or less. You just need to relate the quantity.

  However, if the small-capacity cartridge is a 10K cartridge (for example, a developer amount corresponding to 10000 sheets of A4 size 4% print), the developer amount in the developer accommodating portion is 550 g, and the development remaining in the developer accommodating portion when image blanking occurs. When the amount of the agent is 50 g, the amount of the developer that can be substantially used is 500 g. 25% of this 500 g is 125 g. Further, 1% of the developer amount of 500 g is 5 g. Therefore, in order to sequentially detect the developer amount in increments of 1% from the remaining amount of developer 25%, the change amount of the detected voltage value and the developer with respect to the developer amount change of 5 g or less from the developer amount 125 g or less. The quantity must be related.

  For example, in an image forming apparatus in which a large-capacity cartridge and a small-capacity cartridge as described above can be mounted, it is necessary to detect the amount of developer in the developer container with the same developer amount detection device. Accordingly, considering that the change in developer amount corresponding to the same 1% is detected, the small-capacity cartridge is more severe than the large-capacity cartridge. At present, for small-capacity cartridges, there is a point where the change in the developer amount exceeds the amount equivalent to 1% with a change amount of the detection voltage value smaller than the minimum increment (resolution) of the detection voltage value, and the minimum increment of the detection voltage value Even if the developer remaining amount display is switched for each width (resolution), the detection accuracy slightly deviates.

  This will be further described with reference to FIG. FIG. 16 also shows the relationship between the amount of developer in the developer container and the corresponding detected voltage value for a large capacity (20K) cartridge and a small capacity (10K) cartridge. The horizontal axis indicates the developer remaining amount (%), and decreases from the right side to the left side in the figure. In the graph, the solid line indicates the relationship for the large capacity cartridge, and the broken line indicates the relationship for the small capacity cartridge. In the illustrated example, in the large-capacity cartridge, when the developer remaining amount is less than 25%, the detection voltage value increases as the developer remaining amount (%) decreases.

  As can be seen from the graph of FIG. 16, for example, in a large-capacity cartridge, the change width of the detected voltage value when the developer remaining amount is 25% or less (detected to 10%) is 16 scales (divided) on the vertical scale. It is. This one scale is assumed to be the minimum step width (resolution) of the detected voltage value. In this case, in the small-capacity cartridge, the change width of the detection voltage value when the developer remaining amount is 25% or less (detected to 10%) is smaller than the large-capacity cartridge because the actual developer amount (absolute amount) is smaller. There are only 8 divisions.

  When a large-capacity cartridge and a small-capacity cartridge can be mounted on the same image forming apparatus, under the condition that the minimum step size (resolution) of the detection voltage value is optimized for the large-capacity cartridge, If the developer remaining amount display (%) is sequentially switched when the detection voltage value changes for the minimum step size, the change in the developer remaining amount display (%) will change with respect to the actual developer amount change. Run out of minutes. Considering that the remaining amount of developer from 25% to 10% is detected every 1% in the small-capacity cartridge as well as the large-capacity cartridge, the voltage value change of at least 16 also in the small-capacity cartridge Whereas the number is required, as shown in FIG. 16, the small number of cartridges has eight detected voltage values in increments with respect to the change in the remaining amount of developer from 25% to 10%. Because.

  In other words, when the minimum step size (resolution) of the detection voltage value is optimized for a large-capacity cartridge, the remaining developer display follows the actual change in the remaining developer amount for the small-capacity cartridge. And the correct remaining developer amount (%) cannot be displayed.

  Of course, it is conceivable to separately provide an arithmetic element for a small-capacity cartridge separately from the large-capacity cartridge, and to optimize the small-capacity cartridge by increasing the minimum step size (resolution) of the detection voltage value. Alternatively, it is conceivable that a small-capacity cartridge in which the minimum increment (resolution) of the detection voltage value is optimized (an arithmetic element with improved resolution) is also applied to a large-capacity cartridge. According to these methods, the above problem can be solved.

  However, even if the minimum increment (resolution) of the detection voltage value is increased too much and the resolution is increased more than necessary, the change in the developer amount cannot be captured by the minute change in the detection voltage value, and the detection accuracy does not improve. . In addition, there are cases where the detection accuracy is deteriorated due to excessive sensitivity to noise or the like. Further, if the resolution of the arithmetic element is increased more than necessary in order to increase the detection accuracy, there is a concern that the cost of the arithmetic element will become very high. Furthermore, as described above, it is obvious that the cost increases if the arithmetic elements for the small capacity cartridge and the large capacity cartridge are separately provided.

That is, in the conventional method, the detection voltage value and the developer remaining amount are related one-to-one, and the developer remaining amount display is changed according to the change of the detection voltage value. Therefore, when the change in the developer amount must be detected with the change amount of the detection voltage value smaller than the minimum increment (resolution) of the detection voltage value as described above, the developer remaining amount display is surely displayed every 1%. If it is attempted to update, the change in the detected voltage value may not correspond to the actual developer remaining amount, and the detection accuracy may decrease.
JP 2001-134064 A

  An object of the present invention is to provide an image forming apparatus in which the detection accuracy of the developer amount in the developer accommodating portion is improved.

  One of the more detailed objects of the present invention is that a change in developer amount corresponding to a change in detected value smaller than the minimum change amount (resolution) of the detected value must be detected, that is, the detected value An object of the present invention is to provide an image forming apparatus capable of maintaining high detection accuracy even when the developer amount level step number is larger than the step number.

  The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention provides a developer container, a developer carrier for transporting the developer to the latent image on the image carrier, and a detection for detecting the amount of developer in the developer container. Based on the detection value from the member, the developer amount detection means for generating a detection value corresponding to the developer amount in the developer accommodating portion based on the signal from the detection member, and the developer amount detection means, Control means for switching a developer amount level as a result of detecting the developer amount in the developer accommodating portion, and the control means has the same detection value from the developer amount detection means. Further, the image forming apparatus is characterized in that the developer amount level is switched.

  According to one embodiment of the present invention, the developer amount level is not updated by detecting only the change amount of the detection value, and the developer is detected even if the same detection voltage value is detected again without any change in the detection value. The developer level is associated with the detected value so that the remaining amount is updated. According to another embodiment, the developer amount level is not updated by detecting only the change amount of the detection value, and the development is performed if the same detection value is detected a predetermined number of times even if the detection value does not change. The developer amount level is related to the detection value so as to update the agent amount level. According to still another embodiment, the developer amount level is not updated by detecting only the change amount of the detection value, but if the detection value is continuously detected for a predetermined period even if the detection value does not change, the development is performed. The developer amount level is related to the detection value so as to update the agent amount level.

  Other objects, features, and effects of the present invention will become apparent from the following detailed description.

  According to the present invention, it is possible to improve the detection accuracy of the developer amount. According to the present invention, even under conditions where a change in the developer amount corresponding to a change in the detected value smaller than the minimum change amount (resolution) of the detected value must be detected, that is, the developer amount based on the number of steps of the detected value. Even when the number of level increments is large, the detection accuracy can be maintained with high accuracy.

  The image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

Example 1
[Image forming apparatus and image forming process]
First, an embodiment of an image forming apparatus according to the present invention will be described with reference to FIGS. The image forming apparatus A of this embodiment is an electrophotographic laser beam printer. The image forming apparatus A receives image information from a host computer (or a document reading apparatus) and forms an image on a recording medium (recording paper, OHP sheet, cloth, etc.) by an electrophotographic image forming process.

  The image forming apparatus A includes a cylindrical photosensitive member (hereinafter referred to as “photosensitive drum”) 1. The photosensitive drum 1 is rotationally driven in the direction of the arrow in the figure. The rotating photosensitive drum 1 is charged by a charging roller 2 as charging means. The charged photosensitive drum 1 is irradiated with a laser beam L corresponding to image information by a laser scanner 3 as an exposure unit. As a result, a latent image (electrostatic image) corresponding to the image information is formed on the photosensitive drum 1. This latent image is developed with a developer by the developing means 5 of the developing device C. Thus, a visible image, that is, a developer image (toner image) is formed on the photosensitive drum 1.

  The developing device C includes a developing unit 5 such as a developing roller 5a as a developer carrying member, and a developer storage container 4 that stores a developer used by the developing unit 5. A developer accommodating portion is constituted by the developing chamber 5A to which the developing means 5 is attached and the developer accommodating container 4 formed adjacent to the developing chamber 5A. The developing chamber 5A and the developer storage container 4 communicate with each other through an opening at a position indicated by a broken line in the drawing. Usually, the developing chamber 5A and the developer container 4 are separated by a seal until the use of the developing device C is started. Then, by removing this seal, the developer T in the developer container 4 is supplied to the developing chamber 5A. In this embodiment, as the developer T, a negatively chargeable insulating magnetic one-component developer, that is, a toner was used.

  In the developer storage container 4, a first stirring member 4a and a second stirring member 4b that stir and transport the developer T are provided. The first stirring member 4a is disposed near the developing roller 5a, and conveys the developer T in the direction of the developing roller 5a in the developing chamber 5A while stirring the developer T. The second stirring member 4b is disposed at a position farther from the developing roller 5a than the first stirring member 4a, and conveys the developer T in the direction of the first stirring member 4a while stirring the developer T. The first stirring member 4a and the second stirring member 4b are configured by attaching a sheet-like elastic member such as PET to a plastic rotating shaft.

  The developing roller 5a includes a fixed magnet 5b as a magnetic field generating unit. As the developing roller 5a rotates, the developer (magnetic one-component developer) T restrained on the developing roller 5a by the magnetic field generated by the fixed magnet 5b is conveyed. Further, the developer T on the developing roller 5a is rubbed with a developing blade 5c as a developer layer thickness regulating member to be given a triboelectric charge and to be a developer layer having a predetermined thickness. Then, the toner is supplied to a developing area facing the photosensitive drum 1. The developer T supplied to the development area is transferred onto the photosensitive drum 1 in accordance with the latent image on the photosensitive drum 1 to form a developer image (toner image). The developing roller 5a is connected to a developing bias circuit 34 as a developing bias applying means, and normally, a developing bias voltage in which a DC voltage is superimposed on an AC voltage is applied. The developing roller 5a, the fixed magnet 5b, the developing blade 5c, and the like constitute a developing unit 5 that supplies a developer to the latent image on the photosensitive drum 1. In this embodiment, a reversal development method is used in which the developer T is attached to a portion of the photosensitive drum 1 charged with the same polarity as the developer T, where the potential (absolute value) is attenuated by exposure.

  On the other hand, in synchronization with the formation of the developer image on the photosensitive drum 1, the recording medium P set in the cassette 200 serving as a recording medium accommodating portion is transferred to the transfer position N via the pickup roller 8 and the conveying means 9a. It is conveyed. At the transfer position N, a transfer roller 6 as a transfer unit is disposed to face the photosensitive drum 1. The developer image on the photosensitive drum 1 is transferred to the recording medium P by applying a transfer voltage to the transfer roller 6 from a transfer bias circuit (not shown) as a transfer bias applying unit.

  The recording medium P that has received the transfer of the developer image is conveyed to the heat roller fixing device 10 as a fixing means by the conveying means 9b. The fixing device 10 includes a fixing roller 10b with a built-in heater 10a and a driving roller 10c. The fixing device 10 applies heat and pressure to the passing recording medium P to fix the unfixed developer image transferred on the recording material P onto the recording medium P.

  The recording medium P on which the developer image has been fixed by the fixing device 10 is discharged to the discharge tray 14 via the transport unit 9c. The discharge tray 14 is provided on the upper surface of an image forming apparatus main body (hereinafter simply referred to as “apparatus main body”) 100.

  Further, the developer remaining on the photosensitive drum 1 after the transfer process is removed by a cleaning device 7 as a cleaning means. Thereafter, the photosensitive drum 1 is subjected to the next image forming process. The cleaning device 7 scrapes off the residual developer on the photosensitive drum 1 by a cleaning blade 7a, which is an elastic member provided so as to come into contact with the photosensitive drum 1, and collects it in a waste developer container 7b.

  In this embodiment, the developer storage container 4 and the developing chamber 5A are integrally formed by the developing device frame 11. As a result, the developing chamber 5A (and the developing means 5 such as the developing roller 5a and the developing blade 5c provided in the developing chamber 5A) and the developer storage container 4 (and the first and the second provided in the developer storage container 4). The two stirring members 4a and 4b) form a developing device (developing unit) C integrally. The photosensitive drum 1, the cleaning device 7 including the cleaning blade 7a and the waste developer container 7b, and the charging roller 2 are attached to the cleaning frame 12. The developing device C (developing frame 11) and the cleaning frame 13 are integrally coupled to constitute a process cartridge (hereinafter simply referred to as “cartridge”) B. The cartridge B is detachably mounted on the apparatus main body 100 via mounting means 13 such as a mounting guide and a positioning member provided on the apparatus main body 100. The cartridge B is detachable from the apparatus main body 100 by the user. In this embodiment, the image forming apparatus A can be mounted with a plurality of types of cartridges B having different developer filling amounts when not in use.

[Developer amount detector]
The image forming apparatus A has a developer amount detecting device that can sequentially detect the remaining amount according to consumption of the developer T in the developing device C.

  The developer amount detection device is configured to detect a developer amount in the developer accommodating portion, and to develop the developer in the developer accommodating portion based on a signal output from the detecting means according to the developer amount in the developer accommodating portion. Developer amount detecting means for detecting the amount of developer, and control means for switching the developer amount level as a result of detecting the developer amount in the developer accommodating portion based on a detection value from the developer amount detecting means. . This will be described in more detail below.

  In this embodiment, the developer amount detection device detects the amount of developer in the developer accommodating portion by measuring a change in capacitance between electrode members as detection means. That is, in this embodiment, the developing roller 5a that is a developer carrying member, the first plate antenna (hereinafter referred to as “first sheet metal”) 31 that is a plate-like member as a detection member, and the second plate antenna. (Hereinafter referred to as “second sheet metal”) functions as an electrode member for measuring capacitance and constitutes the detection means 30. As shown in FIG. 2, in the present embodiment, the first sheet metal 31 and the second sheet metal 32 are almost entirely in the longitudinal direction of the developing device C (the rotation axis direction of the developing roller 5 a) at positions facing the developing roller 5 a. Is arranged over. The first sheet metal 31 and the second sheet metal 32 function as output side electrode members that output a signal corresponding to the capacitance induced between the developing roller 5a when a voltage is applied to the developing roller 5a. . The first sheet metal 31 is disposed closer to the developing roller 5 a that functions as an input-side electrode member, and the second sheet metal 32 is disposed farther from the developing roller 5 a than the first sheet metal 31.

  The first sheet metal 31 and the second sheet metal 32 can be used without any particular limitation as long as they are basically materials capable of flowing current. In this embodiment, SUS (stainless steel) that is resistant to rust is used as the material of the first sheet metal 31 and the second sheet metal 32.

  When an AC bias of about 2 KHz, which is a normal developing bias, and a DC bias of about −400 V are applied to the developing roller 5a, the developing roller 5a and the second sheet metal 32 and between the developing roller 5a and the first sheet metal are applied. An alternating current flows between each of them. The current values at this time are measured by the current measuring units 33a and 33b.

  Basically, the second sheet metal 32 disposed at a position far from the developing roller 5a is used for detecting the amount of developer when the amount of developer in the developer containing portion is large, and is disposed at a position close to the developing roller 5a. The first sheet metal 31 is used for detecting the amount of developer at the end of the period from when the amount of developer in the developer accommodating portion decreases to the state of “no developer”.

  Thus, from the current value measured by the current measuring units 33a and 33b, the electrostatic capacitance induced between the developing roller 5a and the second sheet metal 32, and induced between the developing roller 5a and the first sheet metal 31. Capacitance is measured.

  In this way, the first sheet metal 31 and the second sheet metal 32 are disposed in the developing device C, and the developer T in the developing device C decreases between the developing roller 5a and the first sheet metal 31, or By measuring the electrostatic capacity between the developing roller 5a and the second sheet metal 32, it is possible to know the amount of developer in the developer container (development chamber 5A, developer container 4) at any time.

  Referring also to FIG. 3, in the present embodiment, the current from the detection means 30, particularly the first sheet metal 31 and the second sheet metal 32, which are output side electrode members, is supplied to the developer main body 100. It is measured by current measuring units 33a and 33b provided in the main body side developer amount detecting unit 23 as an amount detecting means. Output signals from the detection means 30 (first sheet metal 31 and second sheet metal 32) are converted into voltage signals by a detection value conversion unit 38 provided in the main body side developer amount detection unit 23. The detection signal output from the main body side developer amount detection unit 23 in response to the output signal of the detection unit 30 is sent to the main body control unit 22. The main body control unit 22 determines a developer amount level to be notified to the user using the calculation unit 24, the control unit 25, and the developer remaining amount correction table 26. The main body control unit 22 transmits a signal for displaying information regarding the determined developer amount level to the display unit 40 of the apparatus main body 100.

  In addition to simply displaying the developer amount level, for example, in order to notify the user that the developer has decreased so that image formation of a predetermined quality is impossible, a warning such as “no developer” is issued. Can be displayed. Further, the means for notifying the user of information relating to the developer amount level is not limited to the display means 40 provided in the apparatus main body 100. For example, the main body control unit 22 can transmit a signal for displaying information related to the developer amount level to a host computer that is communicably connected to the apparatus main body 100. Thereby, information relating to the developer amount level may be displayed on a display means such as a monitor of the host computer. Of course, the notification means is not limited to the display mode, and may be by voice, or the image forming apparatus A may record and output it on the recording medium P.

  As described above, the main body developer amount detection unit 23 has the functions of the current measurement unit 33 and the detection value conversion unit 38, and transmits a detection signal as a voltage value to the main body control unit 22. Here, with reference to FIG. 4, the principle of the capacitance measuring method by the main body side developer amount detecting unit 23 will be further described. However, in the present invention, the circuit configuration of the developer amount detection means, the attributes of the output signal, etc. (current value, voltage value, etc.) are not limited at all. The operation content of the main body side developer amount detection unit 23 is substantially the same for each of the first sheet metal 31 and the second sheet metal 32 serving as detection members. I will explain.

  The developing roller 5a is electrically connected to a developing bias circuit 34 as a voltage applying unit (developing bias applying unit) provided in the apparatus main body A in a state where the cartridge B is mounted on the image forming apparatus main body A. Then, an AC bias of about 2 KHz and a DC bias of about −400 V, which are normal development biases, are applied to the developing roller 5a.

  First, when a predetermined AC bias is output from the developing bias circuit 34, the applied bias is applied to the reference capacitor 37 and the developing roller 5a, respectively. As a result, a voltage V1 is generated at both ends of the reference capacitor 37, and a current corresponding to the capacitance C2 between the developing roller 5a and the second sheet metal 32 is generated (current measuring unit). This current value is converted into a voltage V2 by calculation.

  The detection circuit (comparison circuit) 35 generates a voltage V3 from the voltage difference between the voltage V1 generated at both ends of the input reference capacitor 37 and the voltage V2, and outputs the voltage V3 to the AD converter 36. . The AD conversion unit 36 outputs the result of digital conversion of the analog voltage V3 to the main body control unit 22 (detection value conversion unit).

[Developer Amount Level Determination Control Mode]
Next, the principle of the method for determining the developer amount level by the developer amount detection device of this embodiment and the control mode thereof will be described.

  As described above, in the present embodiment, the output signals from the first sheet metal 31 and the second sheet metal functioning as the output side electrode member in the detection unit 30 are converted into voltage values by the main body side developer amount detection unit 23. And input to the main body control unit 22 (hereinafter, this voltage value is referred to as “detected voltage value”).

  As shown in FIG. 3, a memory 20 as a storage medium and a transmission unit 21 are arranged on the cartridge B side. As described above, the main body control unit 22 includes the calculation unit 24, the control unit 25, the developer remaining amount correction table 26, and the like. The main body control unit 22 has a function of a main body side transmission unit that transmits and receives information to and from the transmission unit 21 of the cartridge B. The main body control unit 22 controls writing and reading of information to and from the memory 20 via these transmission units.

  In the main body control unit 22, the calculation unit 24 performs predetermined calculation processing to be described later based on the detected voltage value from the main body side developer amount detection unit 23 and information stored in the memory 20 of the cartridge B. Information stored in the memory 20 is always in a state where it can be transmitted to and received from the arithmetic unit 24 in the main body control unit 22. Then, the control means 25 uses the developer remaining amount correction table 26 to collate data obtained by the calculation by the calculation unit 24, thereby appropriately correcting the detected voltage value and determining the developer amount level. To do. Further, the main body control unit 22 displays information related to the determined developer amount level, for example, on the display means 40 of the apparatus main body 100, or a signal for displaying a warning such as “no developer”. It transmits to the display means 40. In this embodiment, the developer amount level is the remaining amount ratio (%) when the amount of developer obtained by subtracting the amount of developer remaining when image blanking occurs from the amount of unused developer is defined as 100%. indicate.

  The developer remaining amount correction table 26 is stored in a remaining amount detection correction table storage area of a ROM as a storage medium included in the main body control unit 22. The calculation unit 24 and the control unit 25 operate according to the remaining amount detection program, constant data, etc. stored in the ROM, and determine the developer amount level. All or part of the storage medium of the calculation unit 24, the control unit 25, and the developer remaining amount correction table 26 may be a single element.

  Various information can be stored in the memory 20, but in this embodiment, at least the minimum detection voltage value (plate antenna full value: hereinafter referred to as "PAF value") is stored. And This PAF value is the minimum value of the detected voltage value when the first sheet metal 31 and the second sheet metal 32 are both covered with toner. That is, in this embodiment, as shown in FIG. 16, the detected voltage value is small when the developer amount is large, and the detected voltage value is large when the developer amount is small. Accordingly, the minimum value of the detected voltage value means the maximum value in terms of the capacitance detected using the first sheet metal 31 and the second sheet metal 32, and indicates the maximum developer amount in the developer accommodating portion.

[Developer level determination method]
<Outline of developer level determination method>
Hereinafter, a developer amount level determination method (detection voltage value correction method) using the memory 20 of the cartridge B will be further described.

  The main body control unit 22 writes the PAF value in the memory 20. The PAF value stored in the memory 20 is always compared with the detected voltage value by the control means 25. When the detected voltage value X is smaller than the previous value, the PAF value in the memory 20 is rewritten sequentially. In this way, the minimum value of the detected voltage value corresponding to the maximum value of the capacitance detected by the detecting means 30 is always reliably stored in the memory 20 as the PAF value.

  Further, as a table for correcting the detected voltage value, that is, the developer remaining amount correcting table 26 for determining the developer amount level from the detected voltage value X, the amount of change (X from the PAF value of the detected voltage value X) -(PAF value): hereinafter referred to as “detected voltage value difference”) (V) and the relationship between the developer remaining amount (%) in the developing device C as the developer amount level in the main body control unit 22 Store in advance.

  In determining the developer amount level, the calculation unit 24 calculates a detected voltage value difference (V) from the PAF value and the detected voltage value X. Then, the control means 25 refers to the developer remaining amount correction table 26 in which the detected voltage value difference (V) and the developer remaining amount (%) are related to each other, so that the developer at the developer amount level. Determine the remaining amount (%).

  In this way, instead of comparing the raw detection voltage value X with the developer remaining amount (%), the developer remaining amount (%) is calculated based on the amount of deviation of the detected voltage value X from the PAF value. Thereby, individual differences such as positional differences of electrode members (first sheet metal, second sheet metal, etc.) that the cartridge B has individually can be ignored, and the developer amount can be detected with higher accuracy. However, the present invention is not limited to this, and the detection voltage value itself may be related to the developer amount level.

  In the present embodiment, as described above, the developer amount level is obtained by subtracting the developer amount remaining when image blanking occurs from the unused developer amount (substantially usable developer amount). The remaining amount ratio (%) is determined when 100 is set to 100%, and the information is notified. However, the present invention is not limited to this. For example, in the developer remaining amount correction table 26, the detected voltage value difference (V) may be related to the developer amount (g) as the developer amount level. The developer amount (g) may be determined as the developer amount level by the developer remaining amount correction table 26, and the developer remaining amount (%) may be calculated based on the result. Furthermore, the remaining amount of developer (%) is not limited to the remaining amount ratio (%) with respect to the substantially usable developer amount, but the remaining amount ratio with respect to the amount of developer when not in use is determined, and a separate image white It will be easily understood that a warning may be given for missing.

  Here, the image forming apparatus A according to the present embodiment is different from the image forming apparatus in two types, that is, a 20K cartridge as a large capacity cartridge and a 10K cartridge as a small capacity cartridge. The cartridge is removable. In this embodiment, the large-capacity cartridge has a developer amount of 1050 g when not used, a developer amount remaining at the time of image blanking of 50 g, and a substantially usable developer amount of 1000 g. The small-capacity cartridge has an unused developer amount of 550 g, a remaining developer amount of 50 g when the image is blank, and a substantially usable developer amount of 500 g.

  The developer amount detection device provided in the image forming apparatus A of this embodiment is optimal for a large-capacity cartridge. More specifically, the arithmetic element such as the main body developer amount detection unit 23 indicates that the minimum step width (resolution) of the detected voltage value (more specifically, the detected voltage value difference) in the large-capacity cartridge is the developer remaining amount display (%). ) And the step size of 1). Although not limited to this, for example, it corresponds to a situation where a small-capacity cartridge can be used in the same image forming apparatus after the apparatus design.

  In the following, a method for determining the developer amount level for a small-capacity cartridge whose detection accuracy is severe in the conventional method will be described. In consideration of usability, it is desirable to ensure that the developer remaining amount display (%) is in increments of 1%.

  Table 1 shows an example of the developer remaining amount correction table 26 applied to the small capacity cartridge according to the present invention. Table 1 also shows the developer amount (g) in the developing device C corresponding to the developer remaining amount (%).

  Here, only the detection voltage value generated according to the output signal of the second sheet metal 32 far from the developing roller 5a will be described as the detection voltage value X. Table 1 shows the remaining amount of developer (%) from 25% to 10%, which is the detection range of the second sheet metal 32 in this embodiment, and the range where the remaining amount of developer (%) is smaller than that. Omitted. A developer remaining amount (%) of less than 10% is detected by using an output signal of the first sheet metal 31 (details will be described later).

  According to the developer remaining amount correction table 26 of Table 1, the% display of the developer remaining amount is switched from 100% to 25% only when the detected voltage value difference becomes 0.4 V or more. After that, basically, as the detected voltage value difference (V) increases to 0.41 V or more, 0.42 or more,..., The developer remaining amount (%) decreases.

  By the way, in this embodiment, the resolution of the arithmetic element is not increased more than necessary because of the small capacity cartridge. In this embodiment, the arithmetic element is optimized for a large-capacity cartridge, and the minimum change amount (resolution) of the detection voltage value capable of detecting the change in the developer amount is set to 0.01V. That is, in the large-capacity cartridge, every time the detection voltage value (more specifically, the detection voltage value difference) (V) changes by 0.01 V, the developer remaining amount display (%) is changed by 1%.

  In the conventional system, the developer remaining amount display (%) is updated by 1% in correspondence with the change in the detected voltage value for each 0.01 V even for the small-capacity cartridge. Therefore, there was a problem as described above.

  On the other hand, in this embodiment, as shown in Table 1, for example, the detected voltage value difference corresponding to the developer remaining amount display (%) of 23%, 19%, 18%, and 15% is instructed. Absent. That is, for the small-capacity cartridge, the developer remaining amount display (%) and the detected voltage value difference (V) are not related one-to-one.

  In this embodiment, even if the amount of change in the detected voltage value X from the PAF value, that is, the detected voltage value difference (V) does not change, the current developer remaining amount display (%) is switched to. When the detected voltage value is detected again, the developer remaining amount display (%) is switched. In other words, in the present embodiment, at least some of the developer amount levels among the plurality of developer amount levels have the same detection value from the main body developer amount detection unit 23 as the developer amount detection means. Switch the developer level.

  In particular, in this embodiment, when the detected voltage value difference (V) that is the basis for switching to the current developer remaining amount display (%) is detected again after a predetermined period, it is recognized that the amount of developer has decreased. Then, the developer remaining amount display (%) is switched (in this case, 1% lower). That is, in this embodiment, for at least a part of the developer amount levels among the plurality of developer amount levels, the detection value from the main body developer amount detection unit 23 when the developer amount level is switched, and the development The developer amount level is switched when the detection value after a predetermined period after switching the agent amount level is the same value.

  In general, even if the detected voltage value difference (V) once becomes a value necessary for switching the developer remaining amount display (%), the detected voltage value does not continue to maintain that value. It varies. This is used in the method for determining the developer amount level in this embodiment.

  That is, if the detected voltage value difference (V) of 0.41 V is detected even once, the control means 25 refers to the developer remaining amount correction table 26 to display the developer remaining amount display (25%). %) To 24%. Thereafter, the change of the developer remaining amount display (%) to 23% is not based on the detected voltage value difference (V) related to the developer remaining amount display (%) in the developer remaining amount correction table 26. When a detected voltage value difference (V) of 0.41 V is detected again after a predetermined period.

  In this way, it is possible to reduce (update) the developer remaining amount display (%) without changing the detection voltage value.

  Here, in the developer remaining amount correction table 26, which developer remaining amount display (%) is not instructed to indicate the detected voltage value difference (V), in other words, the detected voltage value (detected voltage value difference). Even if there is no change, the value of the developer remaining amount display (%) to be switched to it depends on the actual developer amount and the detected voltage value depending on the configuration of the cartridge (more specifically, the developer container). What is necessary is just to predetermine suitably from relations, such as transition of the above. It is not limited to the aspect of Table 1.

  In addition, during the predetermined period, which is a condition for changing the developer remaining amount display (%) even if there is no change in the detected voltage value difference (V), the amount of developer when an image with the maximum developer consumption is formed. It is set to be equal to or longer than the period corresponding to the number of times of image formation (number of sheets to be passed) on a predetermined recording medium P required to consume the developer amount corresponding to the minimum step width. More specifically, for example, when an image that is 100% printed (entirely printed) like a solid image is continuously formed on an A4 size recording medium P as standard paper, the developer amount is 1% The developer remaining amount display (%) is not switched unless a period corresponding to the number of times of image formation (number of sheets to be passed) required to decrease (the minimum step size of the developer amount level in the embodiment) has elapsed.

  Let us consider a case where, for example, it is necessary to form a solid image on 10 sheets of A4 size recording medium P as standard paper, even though the developer amount is reduced by 1%. In this case, the developer cannot be reduced by 1% until 10 or more sheets of A4 size recording medium P are passed, that is, when the number of passed sheets is less than 10. Therefore, in this case, for example, a period during which image formation is performed on 10 sheets of A4 size recording medium P can be set as the predetermined period. By ignoring the detected voltage value within this predetermined period, erroneous detection of the developer amount can be avoided. That is, for example, when the amount of developer reduced by forming a solid image on A4 size recording medium P, which is standard paper, is the maximum developer consumption in the image forming apparatus, the developer remaining amount display (% ) Is the minimum number of steps, and the number of image formations (number of sheets to be passed) required to consume 1% is defined as a predetermined period. Under this condition, even if the detection voltage value changes greatly within a predetermined period, it is determined that the detected voltage value is noise or erroneous detection, and the developer remaining amount display (%) is not updated within the predetermined period.

  Then, after detecting a desired detection voltage value (detection voltage value based on which the current developer remaining amount display (%) is switched) after this predetermined period, the developer remaining amount display (%) is decreased. By providing such a condition, it is possible to detect the developer amount with high accuracy closer to the actual developer amount change.

  The predetermined period is not limited to switching the developer remaining amount display (%) where there is no change in the detected voltage value, but always after the developer remaining amount display (%) is switched. It is possible to prevent the developer remaining amount display (%) from being switched until the time elapses.

  Also, the detection voltage value difference (V) is not instructed for a plurality of successive developer amount levels, and the developer remaining amount display (%) is switched without changing the detection voltage value difference (V). Also good. For example, in the developer remaining amount correction table 26 shown in Table 1, the detected voltage value difference (V) is instructed for the developer remaining amount display (%) for two consecutive increments of 19% and 18%. Not. In this case, first, when the detection voltage value difference (V) of 0.43 V, which is the basis for switching to the current developer remaining amount display (%) of 20%, is detected again after a predetermined period, the developer remaining amount is displayed. Switch the amount display (%) to 19%. When the detected voltage value difference (V) of 0.43 V is detected again after the same predetermined period has passed, the developer remaining amount display (%) is switched to 18%.

  Naturally, when the detected voltage value difference (V) is instructed in the developer remaining amount correction table 26, the next developer remaining amount display is performed when a value equal to or greater than the detected voltage value difference (V) is detected. Switch to (%).

  Further, in this embodiment, when a detected voltage value difference equal to or greater than the detected voltage value difference that is the basis for switching to the current developer remaining amount display (%) is detected within the predetermined period (for example, according to Table 1). When the current developer remaining amount display (%) is 24% and a detected voltage value difference (V) of 0.42 V is detected), the detected voltage value is ignored and the developer remaining amount is ignored. The display (%) is not updated. This is because it can be determined that the developer remaining amount (%) does not change within a period necessary for the developer consumption amount to be estimated to the maximum and the developer remaining amount to decrease by the minimum step width. Then, after the predetermined period has elapsed, a detected voltage value difference equal to or greater than the detected voltage value difference that is the basis for switching to the current developer remaining amount display (%) as described above is detected (for example, Table 1). In this embodiment, when the current developer remaining amount display (%) is 24% and a detected voltage value difference of 0.42 V is detected), in this embodiment, 23% is skipped and switched to 22%.

<Developer level determination operation>
FIG. 5 is a chart showing an example of an operation for updating the developer remaining amount display (%) by the developer amount level determination method as described above. The vertical axis represents the detected voltage value (in parentheses, the detected voltage value difference when the PAF value is 1.0 V), and the horizontal axis represents the transition of the detected voltage value (detected voltage value difference) over time.

  In FIG. 5, the transition of the actual detected voltage value (detected voltage value difference) is indicated by a solid line. In this embodiment, the main body developer remaining amount detection unit 23 collects detection voltage values every 10 msec, but the value averaged over a certain period is set as one data. Here, the period for one sheet of A4 size recording medium P, which is a standard sheet, is averaged to be one data. In FIG. 5, one segment of the horizontal axis is taken as one data of the detected voltage value (detected voltage value difference) as shown.

  First, according to the developer remaining amount correction table 26 of Table 1, at the first point when the detected voltage value difference (V) changes from 0.39 V to 0.4 V, the developer remaining amount display (%) is switched to 25%. . Similarly, when the detected voltage value difference (V) becomes 0.41 V, the developer remaining amount display (%) is switched to 24%.

  As described above, the developer remaining amount display (%) from 24% to 23% is switched again after a predetermined period, regardless of the change in the detection voltage value difference (V). Performed when a difference (V) is detected. In other words, the detected voltage value difference (V) remains 0.41 V within the predetermined period indicated by the arrow in the figure, but compared to the time when this detected voltage value difference is detected for the first time, the number of sheets passed (detected voltage value). As the number of data) increases, the frequency with which the detected voltage value difference (V) of 0.41 V is detected increases.

  As described above, even when the same detection voltage value is used, when the developer is actually decreased, the detection voltage value is stabilized accordingly. This is utilized in the present embodiment. That is, even if the detection voltage value does not change, when the same detection voltage value is detected again after a predetermined period, the reliability of the detection value has become higher. Thus, the fact that the same detection voltage value can be stably obtained means that the developer has actually decreased. Therefore, by using this, the developer remaining amount display (%) is switched when the same detection voltage value is obtained again after a predetermined period.

  Therefore, if the predetermined period during which the detection voltage value is ignored as described above is 10 sheets (10 points in the number of detection voltage values), the developer remaining amount display (%) is switched to 24%. When the detected voltage value difference (V) of 0.41 V is detected again after the 11th sheet (11 points), the developer remaining amount display (%) is switched to 23%. In the illustrated example, the detected voltage value difference (V) of 0.41 V is detected again for the 11th sheet (11 points), so that the remaining developer amount display (%) is 23 for the 11th sheet (11 points). % Has been switched.

  Thereafter, switching of the developer remaining amount display (%) to 22% is performed when the detected voltage value difference (V) becomes 0.42 V according to the developer remaining amount correction table 26 of Table 1.

  FIG. 6 shows that the remaining developer amount is 19% and 18% when the detected voltage value difference (V) is not indicated with respect to the remaining developer amount display (%) in the remaining developer amount correction table 26 of Table 1. The case where display (%) is switched sequentially is illustrated. In this case, as described above, the detection voltage value for a predetermined period is ignored, and then when the detection voltage value that is the basis for switching the previous developer remaining amount display (%) is detected again, The amount display (%) is switched sequentially.

  Further, FIG. 7 shows a state in which the detected voltage value is ignored for a predetermined period after the developer remaining amount display (%) is switched. That is, a detected voltage value difference (V) of 0.42 V is detected within a predetermined period indicated by an arrow in the figure. However, for the reasons described above, this detected voltage value difference (V) is considered to be erroneous detection and ignored, and the developer remaining amount display (%) is not updated. Then, after this predetermined period of time has elapsed, when the detected voltage value difference (V) of 0.41 V that is the basis for switching to the current developer remaining amount display (%) is detected again, the remaining amount of developer is detected. Switch the display (%) to 23%. However, in this embodiment, if a detected voltage value difference (V) of 0.42 V is detected after a predetermined period as shown by a broken line in the figure, 23% is skipped according to the developer remaining amount correction table 26 of Table 1 and 22 Switch the developer remaining amount display (%) to%.

<Contrast with conventional method>
Here, with reference to Table 2, it is assumed that the developer remaining amount display (%) is switched only by a change in the detected voltage value as in the conventional case, and the effect of this embodiment will be further described.

  Referring to columns A and B of Table 2, according to the conventional method, when the minimum increment of the detected voltage value difference (V) is 0.01 V, the developer remaining only when the detected voltage value changes. Decrease the volume display (%) by 1%. In this case, as in the above-described embodiment, when the voltage difference (V) is 0.4 V and the remaining developer display (%) is 25%, the detected voltage value difference (V) is 0.01 V thereafter. Along with the increase, the developer remaining amount display sequentially changes by 1% from 25% to 10%. In this case, with respect to the change in the developer remaining amount display (%) from 25% to 10%, the change width of the detection voltage value difference (V) is 0.15 V from 0.4 V to 0.55 V.

  On the other hand, the actual developer amount and the remaining amount display are accurately equalized as in the developer remaining amount correction table 26 of Table 1 with the change width of the detected voltage value difference (V) described above. This is not 0.15V but 0.1V from 0.4V to 0.5V. The column C in Table 2 shows the actual developer remaining amount (actual remaining amount) (%) with respect to the detected voltage value difference (V), and the column D shows the actual developer amount (realized image agent amount) (g) at that time. ing.

  The amount of developer viewed from the developer remaining amount display (%) in the column A in Table 2 is the column E in Table 2. According to the conventional method, for example, if the detected voltage value difference (V) is 0.5 V, the developer remaining amount display (%) is set to 15%, and the developer viewed from the developer remaining amount display (%) at this time The amount is assumed to be 75 g. However, as shown in the D column of Table 2, the developer remaining amount (%) is actually 10%, and the actual developer remaining amount at this time is only about 50 g.

  That is, according to the conventional method, the actual developer amount and the display remaining amount are far from each other, and the detection accuracy is poor.

  FIG. 8 shows the relationship between the developer remaining amount (%) determined by the present embodiment and the conventional method and the theoretical value of the developer remaining amount (%). The horizontal axis is the developer remaining amount display (%) viewed from the detected voltage value (V), and the vertical axis is the theoretical value of the developer remaining amount (%). The theoretical value of the remaining amount (%) of the developer is obtained as follows. A small-capacity (10K) cartridge is continuously used as the cartridge B until a blank image is generated with a fixed printing pattern. At this time, if a blank image is generated at the time when image formation is performed on, for example, 10000 sheets of A4 size recording medium P as standard paper, the 7500th sheet is the remaining developer in the ideal system (theoretical value). The theoretical value is obtained from the relationship between the number of sheets calculated from the number of white spots and the remaining amount such that the amount is 25% and the 8000th sheet is 20%. For example, if the actually determined developer remaining amount display (%) is 20% and the number of formed images is 8500th, the theoretical value is 15% for 8500th, so 20% on the horizontal axis. Plotted at 15% on the vertical axis.

  Therefore, in FIG. 8, when the developer remaining amount display (%) actually determined with respect to the theoretical value is small, the developer remaining amount (%) is displayed more than the actual amount, and the detection timing is delayed. Means that

  As can be seen from FIG. 8, in the conventional method (▲) using the developer remaining amount correction table that determines the developer remaining amount display (%) only by the change in the detected voltage value, the detection timing is delayed. On the other hand, as in the present embodiment (■), the developer remaining amount correction table 26 of Table 1 is used, and not only the change of the detected voltage value but also the occurrence state of the voltage value within the same voltage value. If the developer remaining amount display (%) is switched in consideration, a high detection accuracy in which the relationship between the detection timing and the ideal value (%) substantially matches is obtained.

  In the above description, the developer level determination method based on the output signal of the second sheet metal 32 far from the developing roller 5a in the voltage input portion has been described. This is due to the following reason. That is, the change in the capacitance value is very small with respect to the change in the developer amount by the distance from the developing roller 5a which is the voltage input unit. Therefore, the actual voltage value change is also small, and it is difficult to engrave a larger remaining amount% in the small change amount. In such a case, the effect of the present embodiment becomes remarkable.

  A plot (●) for 10% or less in FIG. 8 is a transition of the developer remaining amount display (%) based on the output signal of the first sheet metal 31. Here, in the developer remaining amount (%) range (from 10% to 0%) using the output signal of the first sheet metal 31, the developer remaining amount (%) is obtained only by the change of the detected voltage value, as in the conventional method. The developer remaining amount display (%) is determined using the developer remaining amount correction table to be related, but high detection accuracy is obtained. This is because, as described above, the first sheet metal 31 is small in the number of steps of the developer remaining amount display (%) with a sufficient change width in terms of capacitance, that is, voltage value change. .

  However, the method of the present embodiment can be similarly applied to the first sheet metal 31 close to the voltage input portion. In the first sheet metal 31, the capacitance value that can be changed is large. However, it is effective when the remaining amount of developer (%) is fine and the remaining amount of developer (%) is larger than the number of detected voltage changes from the minimum step width (resolution) of the detected voltage value. Can be.

<Developer amount level determination sequence>
Next, the developer level determination operation in this embodiment will be described with reference to the flowchart of FIG. The developer remaining amount correction table 26 used in the middle is shown in Table 1.

S101: The apparatus main body 100 is turned on.
S102: The main body control unit 22 checks whether or not the PAF value is stored in the memory 20.

Case 1: When “No” is determined in S102 S103: The main body side developer amount detection unit 23 measures the detection voltage value.
S104: The main body control unit 22 stores the measured detection voltage value X as a PAF value in the memory 20, and proceeds to S105.

Case 2: When “YES” is determined in S102 S105: The main body side developer amount detection unit 23 measures the detection voltage value.
S106: The control means 25 compares the PAF value stored in the memory 20 with the detected voltage value X, and confirms whether or not the detected voltage value X is smaller than the PAF value stored in the memory 20. . If “Yes” is determined, the process proceeds to S107, the PAF value in the memory 20 is updated, and then the process returns to S105. If "No" is determined, the process proceeds to S108.
S108: The calculation unit 24 calculates a change amount of the detected voltage value X from the PAF value, that is, a detected voltage value difference (X− (PAF value)) from the PAF value and the detected voltage value X stored in the memory 20. calculate.
S109: The control unit 25 compares the value calculated by the calculation unit 24 in S108 with the developer remaining amount correction table 26.
S110: The controller 25 checks whether the detected voltage value difference calculated in S108 is a value that can update the developer remaining amount display (%) when compared with the developer remaining amount correction table 26. . If “Yes” is determined, the process proceeds to S111. If "No" is determined, the process proceeds to S105, and the measurement of the detected voltage value is started again.
S111: The control means 25 confirms whether the developer remaining amount display (%) is displayed for a predetermined period. If “Yes” is determined, the process proceeds to S112. If "No" is determined, the process proceeds to S105, and the measurement of the detected voltage value is started again.
S112: The control unit 25 transmits a signal indicating that the developer remaining amount display (%) is Y% to the display unit 40 of the apparatus main body 100 and causes the display unit 40 to display the information.
S113: The control means 25 checks whether or not the current developer remaining amount display (%) is a specific remaining amount (%). Here, the specific remaining amount (%) is the developer remaining amount (%) for which the detected voltage value difference is not indicated in the developer remaining amount correction table 26 of Table 1, that is, 23%, 21%. , 19%, 18%, and 15% of the developer remaining before switching (%). That is, 24%, 22%, 20%, 19%, and 16%. If “Yes” is determined, the process proceeds to S114. If “No” is determined, the process proceeds to S120.
S114: The control means 25 ignores the detected voltage value so that the developer remaining amount display (%) is not switched within the predetermined period, and proceeds to S115 when the predetermined period elapses.
S115: The control means 25 confirms whether or not the same detected voltage value difference as the detected voltage value difference when the current developer remaining amount display (%) is switched is detected again. If “Yes” is determined, the process proceeds to S116. If "No" is determined, the process proceeds to S117.
S116: The control means 25 determines that the developer amount level has decreased, and displays the remaining developer amount display (%) by 1%.
S120: The control means 25 checks whether or not the developer remaining amount Y (%) has reached 0%. If “No” is determined, the process proceeds to S105, and the above-described sequence is repeated. If “Yes” is determined, the process advances to step S121 to end the sequence.
S117: In the determination of S115, it was found that the detected voltage value difference is not the same as the detected voltage value difference when the current developer remaining amount display (%) is switched. Here, the control means 25 determines whether or not the detected voltage value difference is larger than the detected voltage value difference when the current developer remaining amount display (%) is switched. If “YES”, that is, it is determined that the value is large, the process proceeds to S118. On the other hand, if “NO”, that is, if it is determined to be small, the process proceeds to S119.
S119: The detection voltage value is measured again, the process proceeds to S115, and the above sequence is repeated.
S118: In the determination of S117, it was determined that the detected voltage value difference was sufficiently large. Here, the control means 25 determines the developer remaining amount display (%) based on the detected voltage value difference based on the developer remaining amount correction table 26 and displays it. Thereafter, the process proceeds to S120.

  Note that a plurality of types of developer remaining amount correction table 26 for the large capacity cartridge and the small capacity cartridge can be set in the main body control unit 22 in advance. That is, for example, the developer remaining amount correction table 26 for both cartridges is stored in each area in the ROM as a storage medium provided in the main body control unit 22. For example, the information stored in the memory 20 on the cartridge B side, the cartridge shape and the like are automatically identified, or the user is connected to the operation unit of the apparatus main body 100 (or the host connected to be communicable with the apparatus main body 100). It is possible to manually detect the type of the cartridge mounted on the apparatus main body 100 by manually inputting from the operation unit) of the device. Thereby, the control means 25 uses the developer remaining amount correction table 26 corresponding to the detected cartridge type, and determines the developer amount level in the developer amount level determination sequence corresponding to the detected cartridge type. be able to.

  As described above, in this embodiment, the remaining amount of developer is obtained based on the remaining developer amount correction table that associates the detected voltage value with the developer amount level basically as in the prior art. Further, at this time, but not limited to this, preferably, the detection voltage value deviation from the detection voltage value (PAF value) corresponding to the maximum developer amount, not the raw detection voltage value, A developer remaining amount correction table that relates the developer amount level is used. In this embodiment, the remaining amount of developer can be detected even when no change in the detected voltage value is observed.

  Here, by increasing the number of changes in the detected voltage value at the minimum step size (resolution) rather than the number of developer amount levels to be displayed, that is, by increasing the resolution of the detected voltage value, in the conventional method as described above. It is possible to solve the problem. However, even if the resolution is higher than necessary, it may become too sensitive to noise and the like, and the detection accuracy of the developer amount may be deteriorated. Therefore, the developer amount cannot be accurately detected only by increasing the resolution in the specification. In addition, if the resolution of the detected voltage value is increased more than necessary, the cost of the arithmetic element may become very high.

  As described above, according to the present embodiment, the detection accuracy can be maintained with high accuracy even under the condition that the change in the developer amount must be detected by the change in the detection value smaller than the minimum change amount (resolution) of the detection value. it can. Also, according to this embodiment, when the detected voltage value changes, the developer remaining amount display is not updated, but the change in the developer remaining amount within the minimum change amount (resolution) of the detected value is the same. More specifically, it is recognized that the same detection value is detected again after a predetermined period, and the developer remaining amount display is updated. As a result, the detection accuracy can be maintained and improved without degrading the detection accuracy of the developer remaining amount under limited conditions.

  In other words, the desired change range can be achieved without increasing the cost of the arithmetic element by increasing the minimum step size (resolution) of the detected value or increasing the cost by providing different arithmetic elements for different types of cartridges. The detection accuracy can be maintained even when the minimum number of detection values (resolution) is smaller than the number of steps of the developer amount level. Thereby, the cost of an apparatus can be held down.

  According to the present embodiment, since the developer amount level can be detected with high accuracy, the timing when the user prepares the replacement cartridge is too late, or the developer amount is detected less than the actual amount. In such cases, there are fewer opportunities to hold the replacement cartridges in excess of necessity, and the usability is excellent.

Example 2
Next, a second embodiment of the present invention will be described. Since the basic configuration and operation of the image forming apparatus of the present embodiment are the same as those of the above embodiment, the elements having substantially the same or corresponding functions and configurations as those of the image forming apparatus of the above embodiment are the same here. Reference numerals are assigned and detailed description is omitted.

[Developer level determination method]
<Overview of determination of developer amount level>
In this embodiment, basically, as in the first embodiment, even if there is no change in the detected voltage value, the developer remaining amount display (%) can be switched according to the change in the developer amount. That is, basically, even when the detected voltage value difference (V) does not change, the detected voltage value that becomes the basis for switching to the current developer remaining amount display (%) is detected again (more specifically, , The remaining amount display (%) of the developer is switched.

  In this embodiment, it is possible to switch the developer remaining amount display (%) more accurately and accurately. Further, the developer remaining amount display (%) can be surely switched for each minimum step size (1% in this embodiment).

  That is, in the first embodiment, the partition value (minimum step size) of the detection voltage value may be jumped according to the developer remaining amount correction table due to noise or variation in the detection amount. Further, the developer remaining amount display (%) may be about every 2%.

  Therefore, in this embodiment, the detection accuracy of the developer amount is further increased, and the developer remaining amount display (%) is surely set for every minimum step width (here, 1%). That is, the sequence is such that the developer remaining amount display (%) always follows the minimum increment from 25%. This will be described in detail below.

  First, also in the present embodiment, as in the first embodiment, the developer remaining amount display (%) is not updated for a predetermined period after the developer remaining amount display (%) is switched. This predetermined period is determined in the same manner as in the first embodiment.

  In this embodiment, the detection value after this predetermined period is developed if the detection voltage value that becomes the basis for switching to the current developer remaining amount (%) as in the first embodiment is detected even once. Instead of switching the remaining amount display (%), the developer remaining amount display (%) is not detected until the detected voltage value is detected a predetermined number of times or when the detected voltage value is continuously detected for a predetermined period. ). As a result, the detection accuracy of the developer amount can be improved, the reliability can be increased, and it can be reliably detected that the developer is decreasing.

  Furthermore, in this embodiment, even when the developer remaining amount display (%) is updated after a predetermined period has elapsed, the change in the developer remaining amount display (%) is assumed to be 1%.

  By adopting such a sequence, the detection accuracy of the developer amount can be further improved and erroneous detection can be prevented.

<Developer level determination operation>
FIG. 10 is a view similar to FIGS. 5 to 7 in the above embodiment. The vertical axis and horizontal axis notations and steps, and the detected voltage value data averaging process are the same as those in each of the above embodiments.

  The process is the same as in FIG. 5 until the developer remaining amount display (%) is switched to 24%. In this embodiment, the developer remaining amount display (%) is displayed after a predetermined period indicated by an arrow in FIG. 10 (here, 10 sheets passed: 10 points in the number of detected voltage values). When the detected voltage value difference (V) of 0.41 V when it is switched to 24% is detected a predetermined number of times (here, 7 points: 7 sheets passed as a period), the developer remaining amount display (% ) To 23%.

  In this way, in this embodiment, whether or not a voltage output value difference (V) of 0.41 V or more has been detected a predetermined number of times (or a predetermined period) in order to confirm that there is no malfunction due to noise or the like after a predetermined period. To monitor. In order to improve the accuracy, it may be monitored whether or not the voltage output value difference is continuously detected a predetermined number of times. In the illustrated example, when the detected voltage value difference (V) of 0.41 V is detected seven times after a predetermined period, or when the detected voltage value difference (V) of 0.41 V is detected seven times continuously. Then, the next developer remaining amount display (%) is switched to 23%.

  Here, the predetermined number of times (or the predetermined period), which is a condition for switching the developer remaining amount display (%) when the same detection voltage value is detected a predetermined number of times (or a predetermined period), is as follows, for example. Can be decided.

  That is, an image with the maximum developer consumption is formed for the predetermined number of times (or a predetermined period), which is a condition for changing the developer remaining amount display (%) even if the detected voltage value difference (V) does not change. In this case, it is possible to set the number of times of image formation (number of sheets to be passed) on a predetermined recording medium P required to consume the developer amount corresponding to the minimum step width of the developer amount level (or equivalent to the number of image formation times). Can be set longer than the period.) More specifically, for example, when an image that is 100% printed (entirely printed) like a solid image is continuously formed on an A4 size recording medium P as standard paper, the developer amount is 1% ( If the number of image formations (number of sheets to be passed) required to decrease (the minimum step width of the developer amount level in this embodiment) has not been reached (if the period corresponding to the number of image formations has not elapsed), the developer remaining amount display Do not switch (%). Let us consider a case where, for example, it is necessary to form a solid image on 10 sheets of A4 size recording medium P as standard paper, even though the developer amount is reduced by 1%. In this case, the developer cannot be reduced by 1% until ten or more sheets of A4 size recording medium P are passed (the number of times of image formation is 10 or more), that is, when the number of sheets is less than 10. Therefore, in this case, for example, the number of times (period) for image formation on 10 sheets of A4 size recording medium P can be set as the predetermined number of times (predetermined period).

  This predetermined number of times (or a predetermined period) is suitable for preventing erroneous detection by examining in advance the degree of occurrence of noise or the like of the detection voltage value according to the configuration of the developer amount detection device. The predetermined number of times (or a corresponding period) may be set as appropriate.

  Switching of the developer remaining amount display (%) to 22% is performed in accordance with the developer remaining amount correction table 26 of Table 1. In this case as well, a predetermined amount of time after the developer remaining amount display (%) is switched to 23%. Switching to 22% is not performed during the period (here, 10 sheets). The developer remaining amount display (%) is switched to 22% only when a detection voltage value difference (V) of 0.42 V is detected after this predetermined period.

  Further, in this embodiment, as described above, the developer remaining amount display (%) is configured to be updated by 1% (protect), so that the detected voltage value difference at the point of switching from 23% to 22%. Even when (V) becomes 0.43 V, the developer remaining amount display (%) is not switched to 20% according to the developer remaining amount correction table 26, but is decreased by 1% and switched to 22%.

<Developer amount level determination sequence>
Next, the developer level determination operation in this embodiment will be described with reference to the flowchart of FIG. The developer remaining amount correction table 26 used in the middle is shown in Table 1.

S201: The apparatus main body 100 is turned on.
S202: The main body control unit 22 checks whether or not the PAF value is stored in the memory 20.

Case 1: When “No” is determined in S202 S203: The main body developer amount detection unit 23 measures the detection voltage value.
S204: The main body control unit 22 stores the measured detection voltage value X as a PAF value in the memory 20, and proceeds to S205.

Case 2: When “YES” is determined in S202, S205: The main body side developer amount detection unit 23 measures the detection voltage value.
S206: The control means 25 compares the PAF value stored in the memory 20 with the detected voltage value X, and confirms whether or not the detected voltage value X is smaller than the PAF value stored in the memory 20. . If “Yes” is determined, the process proceeds to S207 to update the PAF value in the memory 20, and then returns to S205. If “No” is determined, the process proceeds to S208.
S208: The calculation unit 24 calculates a change amount of the detected voltage value X from the PAF value, that is, a detected voltage value difference (X− (PAF value)) from the PAF value and the detected voltage value X stored in the memory 20. calculate.
S209: The control unit 25 compares the value calculated by the calculation unit 24 in S208 with the developer remaining amount correction table 26.
S210: The controller 25 checks whether or not the detected voltage value difference calculated in S208 is a value that can update the developer remaining amount display (%) when compared with the developer remaining amount correction table 26. . If “Yes” is determined, the process proceeds to S211. If “No” is determined, the process proceeds to S205, and the measurement of the detection voltage value is started again.
S211: The control means 25 confirms whether the developer remaining amount display (%) is displayed for a predetermined period. If “Yes” is determined, the process proceeds to S212. If “No” is determined, the process proceeds to S205, and the measurement of the detection voltage value is started again.
S212: The control means 25 reduces the developer remaining amount display (%) by 1%.
S213: The control unit 25 transmits a signal indicating that the developer remaining amount display (%) is Y% to the display unit 40 of the apparatus main body 100, and causes the display unit 40 to display the information.
S214: The control means 25 checks whether or not the current developer remaining amount display (%) is a specific remaining amount (%). The specific remaining amount (%) here is the same as that described in the first embodiment. If “Yes” is determined, the process proceeds to S215. If “No” is determined, the process proceeds to S223.
S215: The control means 25 ignores the detected voltage value so that the developer remaining amount display (%) is not switched within the predetermined period, and proceeds to S216 when the predetermined period has passed.
S216: The control means 25 checks whether or not the same detected voltage value difference as the detected voltage value difference when the current developer remaining amount display (%) is switched is detected again. If it is determined “Yes”, the process proceeds to S217. If “No” is determined, the process proceeds to S220.
S217: The control means 25 confirms whether or not the same detected voltage value difference as the detected voltage value difference when the detected voltage value is switched to the current developer remaining amount display (%) has been detected a predetermined number of times. If “YES”, that is, if it is determined that the predetermined number of times has been detected, the process proceeds to S218. If “NO”, that is, if it is determined that the predetermined number of times has not been detected, the process proceeds to S219.
S219: The detection voltage value is measured again. Thereafter, the process proceeds to S217 again, and it is determined whether or not a desired detection value has been detected a predetermined number of times.
S218: The first means 25 determines that the developer amount level has decreased, and displays the remaining developer display (%) by 1%.
S223: The control means 25 confirms whether or not the developer remaining amount Y (%) has reached 0%. If “No” is determined, the process proceeds to S205, and the above-described sequence is repeated. If “Yes” is determined, the process advances to step S224 to end the sequence.
S220: In the determination of S216, it was found that the detected voltage value difference is not the same as the detected voltage value difference when the current developer remaining amount display (%) is switched. Here, the control means 25 determines whether or not the detected voltage value difference is larger than the detected voltage value difference when the current developer remaining amount display (%) is switched. If “YES”, that is, it is determined that the value is large, the process proceeds to S221. On the other hand, if “NO”, that is, it is determined to be small, the process proceeds to S222.
S222: The detection voltage value is measured again, the process proceeds to S216, and the above sequence is repeated.
S221: In the determination of S220, it was determined that the detected voltage value difference was sufficiently large. Here, the control means 25 determines the developer remaining amount display (%) based on the detected voltage value difference based on the developer remaining amount correction table 26 and displays it. Thereafter, the process proceeds to S223.

  As described above, according to this embodiment, the remaining amount can be detected with higher accuracy, and the developer remaining amount display (%) can be surely reduced every minimum increment% (here, every 1%). . In addition, it becomes clear whether or not the sudden change in the detected voltage value is due to a malfunction such as noise. Accordingly, it is possible to detect the developer amount with higher accuracy by preventing the change of the developer remaining amount display (%) due to the malfunction.

  In other words, according to the present embodiment, even when the detected value is the same, the same effect as in the first embodiment can be obtained by recognizing the change in the developer amount, and the same detected value is set to a predetermined value. The detection accuracy can be further improved by detecting a change in the developer amount level when the number of times (or a predetermined period), preferably continuously, is detected. Further, according to the present embodiment, it is possible to reliably switch the developer remaining amount display for each minimum step size.

Example 3
Next, a third embodiment of the present invention will be described. Since the basic configuration and operation of the image forming apparatus of the present embodiment are the same as those of the above-described embodiment, elements having substantially the same or corresponding functions and configurations as those of the image forming apparatus of the above-described embodiment are denoted by the same reference numerals. A detailed description is omitted.

[Developer level determination method]
<Overview of determination of developer amount level>
In the first embodiment, when switching to the developer remaining amount display (%) in which the detected voltage value difference in the developer remaining amount correction table 26 of Table 1 is not instructed, the current developer remaining amount display (%) is displayed. When the detected voltage value difference (V) that is the basis for switching to is detected again after a predetermined period, the developer remaining amount display (%) is switched.

  In contrast, in this embodiment, even if the amount of change in the detected voltage value X from the PAF value, that is, the detected voltage value difference (V) does not change, the current developer remaining amount display (%) is switched. When the detected value equal to the detected voltage value is detected a predetermined number of times or more, it is recognized that the developer amount has definitely decreased, and the developer remaining amount display (%) is switched (in this case, 1% lower). . In other words, in the present embodiment, at least some of the developer amount levels among the plurality of developer amount levels have the same detection value from the main body developer amount detection unit 23 as the developer amount detection means. In this case, the developer amount level is switched. In particular, the developer amount level is switched when the detection value from the main body developer amount detection unit 23 is the same value a predetermined number of times.

  Further, in order to increase the detection accuracy, the developer amount level is switched when the same detection value is continuously detected a predetermined number of times (or a predetermined period). That is, according to the present embodiment, preferably, at least a part of the developer amount levels among the plurality of developer amount levels, the detection value from the main body developer amount detection unit 23 is the same continuously for a predetermined number of times. If it is a value, the developer amount level is switched. Alternatively, according to this embodiment, it is preferable that at least some of the developer amount levels among the plurality of developer amount levels have the same detection value from the main body developer amount detection unit 23 continuously for a predetermined period. When the value is, the developer amount level is switched.

  That is, if the detected voltage value difference (V) of 0.41 V is detected even once, the control means 25 refers to the developer remaining amount correction table 26 to display the developer remaining amount display (25%). %) To 24%. Thereafter, the change of the developer remaining amount display (%) to 23% is not the detected voltage value difference (V) related to the developer remaining amount display (%) in the developer remaining amount correction table 26 but 0 This is performed when a detected voltage value difference (V) value of .41 V is detected not only once but a predetermined number of times.

  In this way, in this embodiment, it is possible to reduce (update) the developer remaining amount display (%) without changing the detection voltage value.

  Further, as one of the conditions for changing the developer remaining amount display (%), immediately after the developer remaining amount display (%) is switched, the developer remaining amount display (%) is not switched for a predetermined period. Can be added. This protects against sudden false detection. The predetermined period may be determined in the same manner as described in the first embodiment. That is, during this predetermined period, when an image having the maximum developer consumption amount is formed, the number of times of image formation on the predetermined recording medium P required for consuming the developer amount corresponding to the minimum step size of the developer amount level (through The number of sheets is set to be equal to or longer than the period of time. More specifically, for example, when an image that is 100% printed (entirely printed) like a solid image is continuously formed on an A4 size recording medium P as standard paper, the developer amount is 1% The developer remaining amount display (%) is not switched unless a period corresponding to the number of times of image formation (number of sheets to be passed) required to decrease (the minimum step size of the developer amount level in the embodiment) has elapsed.

  Let us consider a case where, for example, it is necessary to form a solid image on 10 sheets of A4 size recording medium P as standard paper, even though the developer amount is reduced by 1%. In this case, the developer cannot be reduced by 1% until 10 or more sheets of A4 size recording medium P are passed, that is, when the number of passed sheets is less than 10. Therefore, in this case, for example, a period during which image formation is performed on 10 sheets of A4 size recording medium P can be set as the predetermined period. By ignoring the detected voltage value within this predetermined period, erroneous detection of the developer amount can be avoided. That is, for example, when the amount of developer reduced by forming a solid image on A4 size recording medium P, which is standard paper, is the maximum developer consumption in the image forming apparatus, the developer remaining amount display (% ) Is the minimum number of steps, and the number of image formations (number of sheets to be passed) required to consume 1% is defined as a predetermined period. Under this condition, even if the detection voltage value changes greatly within a predetermined period, it is determined that the detected voltage value is noise or erroneous detection, and the developer remaining amount display (%) is not updated within the predetermined period.

  Then, after detecting a desired detection voltage value (detection voltage value based on which the current developer remaining amount display (%) is switched) after this predetermined period, the developer remaining amount display (%) is decreased. By providing such a condition, it is possible to detect the developer amount with high accuracy closer to the actual developer amount change.

  Further, in this embodiment, the detected voltage value immediately after the developer remaining amount display (%) is switched is not ignored, but the number of sheets necessary for reducing the developer amount by 1% as described above. (Here, 10 sheets), that is, the predetermined number of times, which is a condition for switching the remaining developer display (%) without changing the detection voltage value, the number of detections corresponding to the same period as the predetermined period. And By doing so, it is possible to detect the developer amount with high accuracy including prevention of erroneous detection. In addition, the developer amount can be detected with higher accuracy on condition that the same detection voltage value is continuously detected for the predetermined number of times (or a corresponding predetermined period).

  The developer remaining amount display (%) is not changed when the detected voltage value does not change, but after the developer remaining amount display (%) is switched, the developer remaining amount is always maintained for the predetermined period. It is possible not to switch the display (%).

  Similarly to the above-described embodiment, no indication of the detected voltage value difference (V) is given to a plurality of continuous developer amount levels, and the remaining amount of developer is displayed without any change in the detected voltage value difference (V). (%) May be switched. For example, in the developer remaining amount correction table 26 shown in Table 1, the detected voltage value difference (V) is instructed for the developer remaining amount display (%) for two consecutive increments of 19% and 18%. Not. In this case, first, when a detection voltage value difference (V) of 0.43 V that is the basis for switching to the current developer remaining amount display (%) of 20% is detected a predetermined number of times (or a predetermined number of times or a predetermined number of times). The developer remaining amount display (%) is switched to 19% when the period is detected continuously. Further, when the detection voltage value difference (V) of 0.43 V is detected a predetermined number of times (or when it is detected a predetermined number of times or continuously for a predetermined period), the developer remaining amount display (%) is displayed as 18%. Switch to.

  Naturally, when the detected voltage value difference (V) is instructed, when a value equal to or greater than the detected voltage value difference (V) is detected, the display is switched to the next developer remaining amount display (%).

<Developer level determination operation>
FIG. 12 is a view similar to FIGS. 5 to 7 and 10 in the above embodiment. The notation of the vertical and horizontal axes, the increments, and the averaging process of the detected voltage value data are the same as those in each of the above embodiments.

  First, according to the developer remaining amount correction table 26 of Table 1, at the first point when the detected voltage value difference (V) changes from 0.39 V to 0.4 V, the developer remaining amount display (%) is switched to 25%. . Similarly, when the detected voltage value difference (V) becomes 0.41 V, the developer remaining amount display (%) is switched to 24%.

  The developer remaining amount display (%) is switched from 24% to 23% as described above, regardless of the change in the detected voltage value difference (V), and the detected voltage value difference (V) of 0.41V. Is performed when a predetermined number of times is detected. That is, the detected voltage value difference (V) remains 0.41 V, but as the detected voltage value difference (V) is detected for the first time, the number of sheets that pass through the sheet (detected voltage) As the number of value data) increases, a detection voltage value difference of 0.41 V has been frequently detected.

  As described above, even when the same detection voltage value is used, when the developer is actually decreased, the detection voltage value is stabilized accordingly. This is utilized in the present embodiment. That is, even if the detection voltage value does not change, the same detection voltage value is detected a predetermined number of times, so that it is possible to detect that the developer has actually decreased, and the developer remaining amount display (%) is reduced. be able to.

  Accordingly, if the same detection voltage value is detected 10 points (10 times) as the condition for switching the developer remaining amount display (%) without changing the detection voltage value as described above, the 11th point When the detected voltage value difference (V) of 0.41 V is detected at (11th time), the developer remaining amount display (%) is switched to 23%.

  As described above, when the detection number of the same detection voltage value, which is a condition for switching the developer remaining amount display (%) without changing the detection voltage value, is assumed to be a solid black image that consumes the developer to the maximum, Number of times corresponding to the number of sheets necessary to consume the minimum amount of developer (here 1%) corresponding to the minimum increment of the remaining amount display (%) (here, the detected voltage value per sheet) Since one data is detected, it is preferable that the number of sheets to be passed corresponds to the number of detections of the detected voltage value. Thereby, it becomes a structure with higher detection accuracy.

  In addition, by setting to switch the developer remaining amount display (%) when the same detection voltage value is continuously detected a predetermined number of times (or for a predetermined period), it is further apparent that the developer has decreased. Therefore, it is possible to detect the developer amount with higher accuracy. Also in this case, the predetermined number of times (or a predetermined period) at which the same detection voltage value is continuously obtained, which is a condition for switching the developer remaining amount display (%), consumes the developer to the maximum extent as described above. When a solid black image is assumed, the number of times corresponding to the number of sheets necessary for consuming the minimum amount of developer (here, 1%) corresponding to the minimum step width of the developer remaining amount display (%) (or (Corresponding period) (here, detection voltage value 1 data is detected for each sheet passing, so the number of sheets passing corresponds to the number of detection of the detection voltage value).

  Thereafter, switching of the developer remaining amount display (%) to 22% is performed when the detected voltage value difference (V) becomes 0.42 V according to the developer remaining amount correction table 26 of Table 1.

  In the same manner as described in Example 1 with reference to FIG. 8, the remaining amount (%) of developer determined according to this example was compared with the theoretical value. As a result, similar to the plot for Example 1 in FIG. 8, it was found that the detection timing according to this example almost matched the theoretical value, and high detection accuracy was obtained.

<Developer amount level determination sequence>
Next, the developer level determination operation in this embodiment will be described with reference to the flowchart of FIG. The developer remaining amount correction table 26 used in the middle is shown in Table 1.

S301: The apparatus main body 100 is turned on.
S302: The main body control unit 22 checks whether or not the PAF value is stored in the memory 20.

Case 1: When “No” is determined in S302 S303: The main body side developer amount detection unit 23 measures the detection voltage value.
S304: The main body control unit 22 stores the measured detection voltage value X as a PAF value in the memory 20, and proceeds to S305.

Case 2: When “YES” is determined in S302, S305: The main body side developer amount detection unit 23 measures the detection voltage value.
S306: The control means 25 compares the PAF value stored in the memory 20 with the detected voltage value X, and confirms whether or not the detected voltage value X is smaller than the PAF value stored in the memory 20. . If “Yes” is determined, the process proceeds to S307, the PAF value in the memory 20 is updated, and then the process returns to S305. If “No” is determined, the process proceeds to S308.
S308: The calculation unit 24 calculates a change amount of the detected voltage value X from the PAF value, that is, a detected voltage value difference (X− (PAF value)) from the PAF value and the detected voltage value X stored in the memory 20. calculate.
S309: The control unit 25 compares the value calculated by the calculation unit 24 in S308 with the developer remaining amount correction table 26.
S310: The control unit 25 transmits a signal indicating that the developer remaining amount display (%) is Y% to the display unit 40 of the apparatus main body 100, and causes the display unit 40 to display the information.
S311: The control means 25 checks whether or not the current developer remaining amount display (%) is a specific remaining amount (%). Here, the specific remaining amount (%) is the developer remaining amount (%) for which the detected voltage value difference is not indicated in the developer remaining amount correction table 26 of Table 1, that is, 23%, 21%. , 19%, 18%, and 15% of the developer remaining before switching (%). That is, 24%, 22%, 20%, 19%, and 16%. If “Yes” is determined, the process proceeds to S312. If “No” is determined, the process proceeds to S313.
S312: The control means 25 determines whether or not the same detected voltage value difference as the detected voltage value difference when the current developer remaining amount display (%) is switched is detected a predetermined number of times. After detecting the predetermined number of times, the developer remaining amount display (%) is reduced by 1% and displayed.
S313: The control means 25 confirms whether or not the developer remaining amount Y (%) has reached 0%. If “No” is determined, the process proceeds to S305, and the above-described sequence is repeated. On the other hand, if “Yes” is determined, the process proceeds to S314 to end the sequence.

  As described above, according to the present embodiment, the detection accuracy can be maintained with high accuracy even under the condition that the change in the developer amount must be detected by the change in the detection value smaller than the minimum change amount (resolution) of the detection value. it can. Also, according to this embodiment, when the detected voltage value changes, the developer remaining amount display is not updated, but the change in the developer remaining amount within the minimum change amount (resolution) of the detected value is the same. The detected value is recognized by detecting a predetermined number of times, and the developer remaining amount display is updated. As a result, the detection accuracy can be maintained and improved without degrading the detection accuracy of the developer remaining amount under limited conditions. Further, according to the present embodiment, the other effects described in the first embodiment can be obtained similarly. In addition, when the same detection value is continuously detected a predetermined number of times (or for a predetermined period), the developer remaining amount display is switched, so that it is recognized more reliably that the developer has decreased, and the detection accuracy is further improved. It is possible to switch the developer remaining amount display high.

Example 4
Next, a fourth embodiment of the present invention will be described. Since the basic configuration and operation of the image forming apparatus of the present embodiment are the same as those of the above embodiment, the elements having substantially the same or corresponding functions and configurations as those of the image forming apparatus of the above embodiment are the same here. Reference numerals are assigned and detailed description is omitted.

[Developer level determination method]
<Overview of determination of developer amount level>
In the present embodiment, basically, as in the third embodiment, even when there is no change in the detected voltage value, the developer remaining amount display (%) can be switched according to the change in the developer amount. That is, basically, even when the detected voltage value difference (V) does not change, the detected voltage value that is the basis for switching to the current developer remaining amount display (%) is detected a predetermined number of times (preferably continuously). The developer remaining amount display (%) is switched at a predetermined number of times or when a predetermined period is detected.

  Further, in this embodiment, the developer remaining amount display (%) can be surely switched for each minimum step size (1% in this embodiment).

  In other words, in the third embodiment, the partition value (minimum step size) of the detected voltage value may be jumped according to the developer remaining amount correction table due to noise or variation in the detected amount. Further, the developer remaining amount display (%) may be about every 2%.

  Therefore, in this embodiment, the developer remaining amount display (%) is surely set for each minimum step size (here, 1%). That is, the sequence is such that the developer remaining amount display (%) always follows the minimum increment from 25%.

  First, also in this embodiment, as in the third embodiment, the developer remaining amount display (%) is not updated for a predetermined period after the developer remaining amount display (%) is switched. This predetermined period is determined in the same manner as in the third embodiment.

  Further, in this embodiment, even when the developer remaining amount display (%) is updated after a predetermined period has elapsed, the change in the developer remaining amount display (%) is assumed to be 1%.

  By adopting such a sequence, the detection accuracy of the developer amount can be further improved and erroneous detection can be prevented.

<Developer level determination operation>
FIG. 14 is a view similar to FIGS. 5 to 7, 10 and 12 in the above embodiment. The notation of the vertical and horizontal axes, the increments, and the averaging process of the detected value data are the same as those in each of the above embodiments.

  The process is the same as in the case of FIG. 12 until the developer remaining amount display (%) is switched to 24%. In the predetermined period indicated by the arrow in the figure (here, 10 sheets are passed: 10 points in the number of detected voltage values), as described above, the sheets that are required to reduce the developer by 1% in the shortest time. The number is the same as the number (detected number) at least (here 10). During this predetermined period, even if the same detection voltage value difference (V) as the detection voltage value difference (V) that is the basis for switching to the current developer remaining amount display (%) is detected a predetermined number of times, the developer remaining amount The display (%) is not switched. Thereby, for example, even if the same detection voltage value is continuously detected and the developer remaining amount display (%) is switched, the detection accuracy is high and substantially matches the realized image agent amount. Here, when the detected voltage value difference (V) of 0.41 V is detected ten times continuously, since the predetermined period has elapsed, the developer remaining amount display (%) is switched to 23%.

  In this embodiment, the developer remaining amount display (%) is further updated by 1% as described above. In FIG. 14, at the point where the developer remaining amount display (%) is switched from 23% to 22%, the detected voltage value difference (V) is 0.43V. If it is normal, at the detection voltage value difference (V) of 0.43 V, the developer remaining amount display (%) is switched to 20% when read from the developer remaining amount correction table 26. However, in this embodiment, the developer remaining amount display (%) is switched by 1% (protect). For this reason, the developer remaining amount display (%) is switched from 23% to 1% by 1%. That is, since it is difficult to think that the remaining amount (%) of the developer is reduced by 2% or more in an extremely short period of time, the remaining amount of developer can be displayed more reliably and accurately with such a configuration. It becomes like this.

<Developer amount level determination sequence>
Next, the developer level determination operation in this embodiment will be described with reference to the flowchart of FIG. The developer remaining amount correction table 26 used in the middle is shown in Table 1.

S401: The apparatus main body 100 is powered on.
S402: The main body control unit 22 checks whether or not a PAF value is stored in the memory 20.

Case 1: When “No” is determined in S402 S403: The main body side developer amount detection unit 23 measures the detection voltage value.
S404: The main body control unit 22 stores the measured detection voltage value X as a PAF value in the memory 20, and proceeds to S405.

Case 2: When “YES” is determined in S402 S405: The main body side developer amount detection unit 23 measures the detection voltage value.
S406: The control means 25 compares the PAF value stored in the memory 20 with the detected voltage X, and confirms whether or not the detected voltage X is smaller than the PAF value stored in the memory 20. If “Yes” is determined, the process proceeds to S407, the PAF value in the memory 20 is updated, and then the process returns to S405. If “No” is determined, the process proceeds to S408.
S408: The calculation unit 24 calculates a change amount of the detected voltage value X from the PAF value, that is, a detected voltage value difference (X− (PAF value)) from the PAF value and the detected voltage value X stored in the memory 20. calculate.
S409: The control unit 25 compares the value calculated by the calculation unit 24 in S408 with the developer remaining amount correction table 26.
S410: The control means 25 confirms whether or not the developer remaining amount display (%) collated in the developer remaining amount correction table 26 is updated. If it is determined “Yes”, the process proceeds to S411. If “No” is determined, the process advances to step S405 to repeat the above sequence.
S411: The control means 25 reduces the developer remaining amount display (%) by 1%.
S412: The control means 25 transmits a signal indicating that the developer remaining amount display (%) is Y% to the display unit 40 of the apparatus main body 100 and causes the display unit 40 to display the information.
S413: The control means 25 checks whether or not the current developer remaining amount display (%) is a specific remaining amount (%). The specific remaining amount (%) here is the same as that described in the third embodiment. If “Yes” is determined, the process proceeds to S414. If “No” is determined, the process proceeds to S415.
S414: The control means 25 determines whether or not the same detected voltage value difference as the detected voltage value difference when the current developer remaining amount display (%) is switched is detected a predetermined number of times. When the predetermined number of times is detected, the developer remaining amount display (%) is reduced by 1% and displayed.
S415: The control means 25 confirms whether or not the developer remaining amount Y (%) has reached 0%. If “No” is determined, the process proceeds to S405, and the above-described sequence is repeated. On the other hand, if “Yes” is determined, the process proceeds to S 416 to end the sequence.

  As described above, according to the present embodiment, the developer remaining amount display (%) can be surely reduced at every minimum increment (here, every 1%). In addition, it becomes clear whether or not the sudden change in the detected voltage value is due to a malfunction such as noise. As a result, the change in the developer remaining amount display (%) due to malfunction is eliminated, and the developer amount can be detected with higher accuracy.

(Other examples)
The correction table and the various predetermined values described in the above embodiments differ depending on the configurations of the image forming apparatus and the process cartridge. Therefore, the correction table is not limited to those in the above embodiments, and may be appropriately changed depending on each configuration. it can.

  In the above embodiment, the developer remaining amount correction correction table has been described as being stored in the main body control unit 22, but may be stored in the memory on the cartridge side. In this case, a table corresponding to the characteristics of each cartridge can be used while being held in the cartridge itself, and more accurate detection of the remaining amount of toner can be performed.

  In the above embodiment, the increase / decrease relationship between the capacitance value detected by the detection means and the detection output value of the main body developer amount detection unit is reversed (the detection output value increases as the capacitance value decreases). This relationship varies depending on the circuit provided in the image forming apparatus. Even if the relationship between the capacitance and the voltage is the same decreasing function, it is an increasing function. It doesn't matter.

  In the above embodiment, the detection unit is described as measuring the electrostatic capacity between the developer carrier and the sheet metal, but the present invention is not limited to this. For example, more detection members (electrode members such as sheet metal) may be provided in order to increase the detection accuracy of the developer amount, and the capacitance between the detection members such as sheet metal may be measured. Further, in the above-described embodiment, it has been described that the remaining amount of developer can be detected sequentially from the time when the remaining amount of developer becomes small (25%). However, when a larger amount of toner remains. The remaining amount of developer may be detected sequentially. For this purpose, other developer remaining amount detecting means may be combined. For example, by providing an electrode member at the bottom of the developing container, the remaining amount of toner may be detected sequentially from the time when the remaining amount of developer is larger.

  Here, the sequential detection of the remaining amount of developer means not only the sequential detection in all areas from the state where the remaining amount of developer is 100% to 0%, but also development such as 50% and 15%. It also includes detecting sequentially from the state in which the agent is decreased. Further, the remaining amount of the developer of 0% does not mean that the developer in the developing device has completely disappeared. For example, the developer remaining that makes it difficult to form an image of a predetermined quality. The amount and the like include a state where a predetermined amount of developer obtained in advance remains. Naturally, for example, information indicating that there is no developer or that there is almost no developer may be notified instead of information such as “0%” or “1%”.

  As the developer remaining amount detection means, the one of the electrostatic capacity detection method described in the above embodiment is suitable because the detection accuracy is good and the circuit configuration is relatively simple. The invention is not limited to this. A signal corresponding to the amount of developer in the developer container can be sequentially output, for example, because the minimum step size of the detection value is optimized in any of a plurality of types of cartridges, etc. In the case where the number of steps of the developer remaining amount (%) may exceed the number of changes in the detected voltage as viewed from the minimum step width (resolution) of the detected voltage value, the present invention preferably operates. Similar effects can be achieved. A plurality of detection means may be used in combination.

  In each of the above embodiments, the cartridge that can be attached to and detached from the apparatus main body has been described as a process cartridge in which a photosensitive drum, a charging roller, a developing device, and a cleaning device are integrated into a cartridge. It is not limited. The process cartridge includes a photosensitive member and at least one of a charging unit, a developing unit, and a cleaning unit as a process unit that acts on the photosensitive unit, and is integrated into a cartridge so that it can be attached to and detached from the apparatus main body. It is. Further, the present invention is equally applicable when the developing device (developing unit C in the above-described embodiment) is a cartridge (developing cartridge) that can be detachably attached to the apparatus main body. In this case, the configuration of the developing cartridge corresponds to the developing unit C excluding the photosensitive drum, the charging roller, and the cleaning device from the process cartridge B in each of the above embodiments. In this case, it can be considered that the memory on the cartridge side is provided in the developing cartridge. Furthermore, the present invention can be equally applied to a case in which the developer accommodating portion is detachably attached to the main body of the image forming apparatus as a cartridge detachable from the image forming apparatus. For example, a case where a functional element corresponding to the developer container in the above embodiment is detachable from the image forming apparatus is exemplified.

  In the above embodiment, the image forming apparatus is described as forming a single color image, but the present invention is not limited to this. The present invention can be equally applied to an image forming apparatus that includes a plurality of developing units and forms images of a plurality of colors (for example, a two-color image, a three-color image, or a full color). In this case, the developer amount level determination control may be applied to each developer accommodating portion that accommodates the developer used in each developing unit as in the above embodiment.

  As a developing method, various developing methods such as a magnetic brush developing method using a known two-component developer as well as jumping development using the one-component magnetic developer in the above-described embodiment can be used.

1 is a cross-sectional view of an embodiment of an image forming apparatus according to the present invention. FIG. 2 is an enlarged cross-sectional view of a cartridge mounted on the image forming apparatus in FIG. 1. FIG. 2 is a block diagram illustrating an example of a control mode of the image forming apparatus in FIG. 1. It is a figure which shows an example of the circuit structure of a developer amount detection apparatus. It is explanatory drawing of one Example of the switching operation | movement of the developer residual amount display according to this invention. It is explanatory drawing of the other Example of the switching operation | movement of the developer residual amount display according to this invention. It is explanatory drawing of the other Example of the switching operation | movement of the developer residual amount display according to this invention. It is a graph which shows the effect of this invention. It is a flowchart figure of one Example of switching operation | movement of the developer residual amount display according to this invention. It is explanatory drawing of the other Example of the switching operation | movement of the developer residual amount display according to this invention. FIG. 12 is a flowchart of another embodiment of the switching operation of the developer remaining amount display according to the present invention. It is explanatory drawing of the other Example of the switching operation | movement of the developer residual amount display according to this invention. FIG. 12 is a flowchart of another embodiment of the switching operation of the developer remaining amount display according to the present invention. It is explanatory drawing of the other Example of the switching operation | movement of the developer residual amount display according to this invention. FIG. 12 is a flowchart of another embodiment of the switching operation of the developer remaining amount display according to the present invention. It is a graph for demonstrating the subject which invention will solve.

Explanation of symbols

1 Photosensitive drum (image carrier)
2 Charging roller (charging means)
3 Laser scanner (exposure means)
4 Developer container (developer container)
5 Developing means 5a Developing roller (developer carrier, electrode member)
5A Development chamber (developer container)
7 Cleaning device (cleaning means)
20 memory (storage means, storage medium)
22 Main body control unit 25 Control means 30 Detection means 31 First sheet metal (electrode member, detection member)
32 2nd sheet metal (electrode member, detection member)
40 Display means 100 Image forming apparatus main body A Laser beam printer (image forming apparatus)
B Process cartridge (cartridge)
C Development device (development unit, development cartridge)

Claims (17)

A developer container, a developer carrier for transporting the developer to the latent image on the image carrier, a detection member for detecting the amount of developer in the developer container, and the detection member A developer amount detecting means for generating a detection value corresponding to the developer amount in the developer containing portion based on the signal; and a developer in the developer containing portion based on the detected value from the developer amount detecting means Control means for switching the developer amount level as a result of detecting the amount,
The image forming apparatus, wherein the control unit switches the developer amount level when the detection values from the developer amount detection unit are the same value.   The control unit detects the detection value from the developer amount detection unit when the developer amount level is switched and the developer amount detection unit after a predetermined period after switching the developer amount level. The image forming apparatus according to claim 1, wherein when the detected value is the same value, the developer amount level is switched.   The control unit detects the detection value from the developer amount detection unit when the developer amount level is switched and the developer amount detection unit after a predetermined period after switching the developer amount level. 2. The image forming apparatus according to claim 1, wherein when the detected value is the same and the detected value detected by the developer amount detecting means is detected a predetermined number of times, the developer amount level is switched. .   The control unit detects the detection value from the developer amount detection unit when the developer amount level is switched and the developer amount detection unit after a predetermined period after switching the developer amount level. 2. The developer amount level is switched when the detected value is the same and the detected value detected by the developer amount detecting means is detected a predetermined number of times or continuously for a predetermined period. The image forming apparatus described in 1.   The predetermined period after switching the developer amount level is a predetermined period required to consume a developer amount corresponding to the minimum step width of the developer amount level when an image having the maximum developer consumption amount is formed. The image forming apparatus according to claim 1, wherein the image forming apparatus is set to be equal to or longer than a period corresponding to the number of times of image formation on the recording medium.   The image forming apparatus according to claim 1, wherein the control unit switches the developer amount level when the detected value from the developer amount detecting unit is the same value a predetermined number of times.   2. The image forming apparatus according to claim 1, wherein the control unit switches the developer amount level when the detected value from the developer amount detecting unit is the same value continuously for a predetermined number of times.   The predetermined number of times is a period corresponding to the number of times of image formation for a predetermined recording medium required to consume the developer amount corresponding to the minimum step size of the development amount level when an image having the maximum developer consumption amount is formed. The image forming apparatus according to claim 6, wherein the image forming apparatus is set to have the above-described period.   The image forming apparatus according to claim 1, wherein the control unit switches the developer amount level when the detected value from the developer amount detecting unit is the same value continuously for a predetermined period.   The predetermined period corresponds to the number of times of image formation on a predetermined recording medium required to consume the developer amount corresponding to the minimum step width of the developer amount level when an image having the maximum developer consumption amount is formed. The image forming apparatus according to claim 9, wherein the image forming apparatus is set to be equal to or longer than a period.   The image forming apparatus according to claim 1, wherein the control unit switches the developer amount level for each minimum step size.   The image according to claim 1, wherein the detection member has at least a pair of electrode members and outputs a signal corresponding to a change in capacitance between the electrode members. Forming equipment.   The image forming apparatus according to claim 1, wherein the detection member outputs a signal corresponding to a change in capacitance between the detection member and the developer carrier.   The image forming apparatus according to claim 1, wherein a cartridge having at least the developer accommodating portion is detachable.   The image forming apparatus according to claim 1, wherein a cartridge having at least the developer containing portion, the developer carrying member, and the detection member is detachable.   15. The cartridge further comprises at least one of an electrophotographic photosensitive member as the image carrier, a charging unit for charging the electrophotographic photosensitive member, and a cleaning unit for cleaning the electrophotographic photosensitive member. Or 15 image forming apparatuses.   17. The image forming apparatus according to claim 14, 15 or 16, wherein a plurality of types of the cartridges having different amounts of developer accommodated in the developer accommodating portion are detachable when not in use.

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